FFMPEG-FILTERS(1)					     FFMPEG-FILTERS(1)

NAME
       ffmpeg-filters - FFmpeg filters

DESCRIPTION
       This document describes filters, sources, and sinks provided by the
       libavfilter library.

FILTERING INTRODUCTION
       Filtering in FFmpeg is enabled through the libavfilter library.

       In libavfilter, a filter can have multiple inputs and multiple outputs.
       To illustrate the sorts of things that are possible, we consider the
       following filtergraph.

			       [main]
	       input --> split ---------------------> overlay --> output
			   |				 ^
			   |[tmp]		   [flip]|
			   +-----> crop --> vflip -------+

       This filtergraph splits the input stream in two streams, then sends one
       stream through the crop filter and the vflip filter, before merging it
       back with the other stream by overlaying it on top. You can use the
       following command to achieve this:

	       ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT

       The result will be that the top half of the video is mirrored onto the
       bottom half of the output video.

       Filters in the same linear chain are separated by commas, and distinct
       linear chains of filters are separated by semicolons. In our example,
       crop,vflip are in one linear chain, split and overlay are separately in
       another. The points where the linear chains join are labelled by names
       enclosed in square brackets. In the example, the split filter generates
       two outputs that are associated to the labels [main] and [tmp].

       The stream sent to the second output of split, labelled as [tmp], is
       processed through the crop filter, which crops away the lower half part
       of the video, and then vertically flipped. The overlay filter takes in
       input the first unchanged output of the split filter (which was
       labelled as [main]), and overlay on its lower half the output generated
       by the crop,vflip filterchain.

       Some filters take in input a list of parameters: they are specified
       after the filter name and an equal sign, and are separated from each
       other by a colon.

       There exist so-called source filters that do not have an audio/video
       input, and sink filters that will not have audio/video output.

GRAPH
       The graph2dot program included in the FFmpeg tools directory can be
       used to parse a filtergraph description and issue a corresponding
       textual representation in the dot language.

       Invoke the command:

	       graph2dot -h

       to see how to use graph2dot.

       You can then pass the dot description to the dot program (from the
       graphviz suite of programs) and obtain a graphical representation of
       the filtergraph.

       For example the sequence of commands:

	       echo <GRAPH_DESCRIPTION> | \
	       tools/graph2dot -o graph.tmp && \
	       dot -Tpng graph.tmp -o graph.png && \
	       display graph.png

       can be used to create and display an image representing the graph
       described by the GRAPH_DESCRIPTION string. Note that this string must
       be a complete self-contained graph, with its inputs and outputs
       explicitly defined.  For example if your command line is of the form:

	       ffmpeg -i infile -vf scale=640:360 outfile

       your GRAPH_DESCRIPTION string will need to be of the form:

	       nullsrc,scale=640:360,nullsink

       you may also need to set the nullsrc parameters and add a format filter
       in order to simulate a specific input file.

FILTERGRAPH DESCRIPTION
       A filtergraph is a directed graph of connected filters. It can contain
       cycles, and there can be multiple links between a pair of filters. Each
       link has one input pad on one side connecting it to one filter from
       which it takes its input, and one output pad on the other side
       connecting it to one filter accepting its output.

       Each filter in a filtergraph is an instance of a filter class
       registered in the application, which defines the features and the
       number of input and output pads of the filter.

       A filter with no input pads is called a "source", and a filter with no
       output pads is called a "sink".

   Filtergraph syntax
       A filtergraph has a textual representation, which is recognized by the
       -filter/-vf/-af and -filter_complex options in ffmpeg and -vf/-af in
       ffplay, and by the "avfilter_graph_parse_ptr()" function defined in
       libavfilter/avfilter.h.

       A filterchain consists of a sequence of connected filters, each one
       connected to the previous one in the sequence. A filterchain is
       represented by a list of ","-separated filter descriptions.

       A filtergraph consists of a sequence of filterchains. A sequence of
       filterchains is represented by a list of ";"-separated filterchain
       descriptions.

       A filter is represented by a string of the form:
       [in_link_1]...[in_link_N]filter_name@id=arguments[out_link_1]...[out_link_M]

       filter_name is the name of the filter class of which the described
       filter is an instance of, and has to be the name of one of the filter
       classes registered in the program optionally followed by "@id".	The
       name of the filter class is optionally followed by a string
       "=arguments".

       arguments is a string which contains the parameters used to initialize
       the filter instance. It may have one of two forms:

       ·   A ':'-separated list of key=value pairs.

       ·   A ':'-separated list of value. In this case, the keys are assumed
	   to be the option names in the order they are declared. E.g. the
	   "fade" filter declares three options in this order -- type,
	   start_frame and nb_frames. Then the parameter list in:0:30 means
	   that the value in is assigned to the option type, 0 to start_frame
	   and 30 to nb_frames.

       ·   A ':'-separated list of mixed direct value and long key=value
	   pairs. The direct value must precede the key=value pairs, and
	   follow the same constraints order of the previous point. The
	   following key=value pairs can be set in any preferred order.

       If the option value itself is a list of items (e.g. the "format" filter
       takes a list of pixel formats), the items in the list are usually
       separated by |.

       The list of arguments can be quoted using the character ' as initial
       and ending mark, and the character \ for escaping the characters within
       the quoted text; otherwise the argument string is considered terminated
       when the next special character (belonging to the set []=;,) is
       encountered.

       The name and arguments of the filter are optionally preceded and
       followed by a list of link labels.  A link label allows one to name a
       link and associate it to a filter output or input pad. The preceding
       labels in_link_1 ... in_link_N, are associated to the filter input
       pads, the following labels out_link_1 ... out_link_M, are associated to
       the output pads.

       When two link labels with the same name are found in the filtergraph, a
       link between the corresponding input and output pad is created.

       If an output pad is not labelled, it is linked by default to the first
       unlabelled input pad of the next filter in the filterchain.  For
       example in the filterchain

	       nullsrc, split[L1], [L2]overlay, nullsink

       the split filter instance has two output pads, and the overlay filter
       instance two input pads. The first output pad of split is labelled
       "L1", the first input pad of overlay is labelled "L2", and the second
       output pad of split is linked to the second input pad of overlay, which
       are both unlabelled.

       In a filter description, if the input label of the first filter is not
       specified, "in" is assumed; if the output label of the last filter is
       not specified, "out" is assumed.

       In a complete filterchain all the unlabelled filter input and output
       pads must be connected. A filtergraph is considered valid if all the
       filter input and output pads of all the filterchains are connected.

       Libavfilter will automatically insert scale filters where format
       conversion is required. It is possible to specify swscale flags for
       those automatically inserted scalers by prepending "sws_flags=flags;"
       to the filtergraph description.

       Here is a BNF description of the filtergraph syntax:

	       <NAME>		  ::= sequence of alphanumeric characters and '_'
	       <FILTER_NAME>	  ::= <NAME>["@"<NAME>]
	       <LINKLABEL>	  ::= "[" <NAME> "]"
	       <LINKLABELS>	  ::= <LINKLABEL> [<LINKLABELS>]
	       <FILTER_ARGUMENTS> ::= sequence of chars (possibly quoted)
	       <FILTER> 	  ::= [<LINKLABELS>] <FILTER_NAME> ["=" <FILTER_ARGUMENTS>] [<LINKLABELS>]
	       <FILTERCHAIN>	  ::= <FILTER> [,<FILTERCHAIN>]
	       <FILTERGRAPH>	  ::= [sws_flags=<flags>;] <FILTERCHAIN> [;<FILTERGRAPH>]

   Notes on filtergraph escaping
       Filtergraph description composition entails several levels of escaping.
       See the "Quoting and escaping" section in the ffmpeg-utils(1) manual
       for more information about the employed escaping procedure.

       A first level escaping affects the content of each filter option value,
       which may contain the special character ":" used to separate values, or
       one of the escaping characters "\'".

       A second level escaping affects the whole filter description, which may
       contain the escaping characters "\'" or the special characters "[],;"
       used by the filtergraph description.

       Finally, when you specify a filtergraph on a shell commandline, you
       need to perform a third level escaping for the shell special characters
       contained within it.

       For example, consider the following string to be embedded in the
       drawtext filter description text value:

	       this is a 'string': may contain one, or more, special characters

       This string contains the "'" special escaping character, and the ":"
       special character, so it needs to be escaped in this way:

	       text=this is a \'string\'\: may contain one, or more, special characters

       A second level of escaping is required when embedding the filter
       description in a filtergraph description, in order to escape all the
       filtergraph special characters. Thus the example above becomes:

	       drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters

       (note that in addition to the "\'" escaping special characters, also
       "," needs to be escaped).

       Finally an additional level of escaping is needed when writing the
       filtergraph description in a shell command, which depends on the
       escaping rules of the adopted shell. For example, assuming that "\" is
       special and needs to be escaped with another "\", the previous string
       will finally result in:

	       -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"

TIMELINE EDITING
       Some filters support a generic enable option. For the filters
       supporting timeline editing, this option can be set to an expression
       which is evaluated before sending a frame to the filter. If the
       evaluation is non-zero, the filter will be enabled, otherwise the frame
       will be sent unchanged to the next filter in the filtergraph.

       The expression accepts the following values:

       t   timestamp expressed in seconds, NAN if the input timestamp is
	   unknown

       n   sequential number of the input frame, starting from 0

       pos the position in the file of the input frame, NAN if unknown

       w
       h   width and height of the input frame if video

       Additionally, these filters support an enable command that can be used
       to re-define the expression.

       Like any other filtering option, the enable option follows the same
       rules.

       For example, to enable a blur filter (smartblur) from 10 seconds to 3
       minutes, and a curves filter starting at 3 seconds:

	       smartblur = enable='between(t,10,3*60)',
	       curves	 = enable='gte(t,3)' : preset=cross_process

       See "ffmpeg -filters" to view which filters have timeline support.

OPTIONS FOR FILTERS WITH SEVERAL INPUTS
       Some filters with several inputs support a common set of options.
       These options can only be set by name, not with the short notation.

       eof_action
	   The action to take when EOF is encountered on the secondary input;
	   it accepts one of the following values:

	   repeat
	       Repeat the last frame (the default).

	   endall
	       End both streams.

	   pass
	       Pass the main input through.

       shortest
	   If set to 1, force the output to terminate when the shortest input
	   terminates. Default value is 0.

       repeatlast
	   If set to 1, force the filter to extend the last frame of secondary
	   streams until the end of the primary stream. A value of 0 disables
	   this behavior.  Default value is 1.

AUDIO FILTERS
       When you configure your FFmpeg build, you can disable any of the
       existing filters using "--disable-filters".  The configure output will
       show the audio filters included in your build.

       Below is a description of the currently available audio filters.

   acompressor
       A compressor is mainly used to reduce the dynamic range of a signal.
       Especially modern music is mostly compressed at a high ratio to improve
       the overall loudness. It's done to get the highest attention of a
       listener, "fatten" the sound and bring more "power" to the track.  If a
       signal is compressed too much it may sound dull or "dead" afterwards or
       it may start to "pump" (which could be a powerful effect but can also
       destroy a track completely).  The right compression is the key to reach
       a professional sound and is the high art of mixing and mastering.
       Because of its complex settings it may take a long time to get the
       right feeling for this kind of effect.

       Compression is done by detecting the volume above a chosen level
       "threshold" and dividing it by the factor set with "ratio".  So if you
       set the threshold to -12dB and your signal reaches -6dB a ratio of 2:1
       will result in a signal at -9dB. Because an exact manipulation of the
       signal would cause distortion of the waveform the reduction can be
       levelled over the time. This is done by setting "Attack" and "Release".
       "attack" determines how long the signal has to rise above the threshold
       before any reduction will occur and "release" sets the time the signal
       has to fall below the threshold to reduce the reduction again. Shorter
       signals than the chosen attack time will be left untouched.  The
       overall reduction of the signal can be made up afterwards with the
       "makeup" setting. So compressing the peaks of a signal about 6dB and
       raising the makeup to this level results in a signal twice as loud than
       the source. To gain a softer entry in the compression the "knee"
       flattens the hard edge at the threshold in the range of the chosen
       decibels.

       The filter accepts the following options:

       level_in
	   Set input gain. Default is 1. Range is between 0.015625 and 64.

       threshold
	   If a signal of stream rises above this level it will affect the
	   gain reduction.  By default it is 0.125. Range is between
	   0.00097563 and 1.

       ratio
	   Set a ratio by which the signal is reduced. 1:2 means that if the
	   level rose 4dB above the threshold, it will be only 2dB above after
	   the reduction.  Default is 2. Range is between 1 and 20.

       attack
	   Amount of milliseconds the signal has to rise above the threshold
	   before gain reduction starts. Default is 20. Range is between 0.01
	   and 2000.

       release
	   Amount of milliseconds the signal has to fall below the threshold
	   before reduction is decreased again. Default is 250. Range is
	   between 0.01 and 9000.

       makeup
	   Set the amount by how much signal will be amplified after
	   processing.	Default is 1. Range is from 1 to 64.

       knee
	   Curve the sharp knee around the threshold to enter gain reduction
	   more softly.  Default is 2.82843. Range is between 1 and 8.

       link
	   Choose if the "average" level between all channels of input stream
	   or the louder("maximum") channel of input stream affects the
	   reduction. Default is "average".

       detection
	   Should the exact signal be taken in case of "peak" or an RMS one in
	   case of "rms". Default is "rms" which is mostly smoother.

       mix How much to use compressed signal in output. Default is 1.  Range
	   is between 0 and 1.

   acontrast
       Simple audio dynamic range commpression/expansion filter.

       The filter accepts the following options:

       contrast
	   Set contrast. Default is 33. Allowed range is between 0 and 100.

   acopy
       Copy the input audio source unchanged to the output. This is mainly
       useful for testing purposes.

   acrossfade
       Apply cross fade from one input audio stream to another input audio
       stream.	The cross fade is applied for specified duration near the end
       of first stream.

       The filter accepts the following options:

       nb_samples, ns
	   Specify the number of samples for which the cross fade effect has
	   to last.  At the end of the cross fade effect the first input audio
	   will be completely silent. Default is 44100.

       duration, d
	   Specify the duration of the cross fade effect. See the Time
	   duration section in the ffmpeg-utils(1) manual for the accepted
	   syntax.  By default the duration is determined by nb_samples.  If
	   set this option is used instead of nb_samples.

       overlap, o
	   Should first stream end overlap with second stream start. Default
	   is enabled.

       curve1
	   Set curve for cross fade transition for first stream.

       curve2
	   Set curve for cross fade transition for second stream.

	   For description of available curve types see afade filter
	   description.

       Examples

       ·   Cross fade from one input to another:

		   ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:c1=exp:c2=exp output.flac

       ·   Cross fade from one input to another but without overlapping:

		   ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:o=0:c1=exp:c2=exp output.flac

   acrusher
       Reduce audio bit resolution.

       This filter is bit crusher with enhanced functionality. A bit crusher
       is used to audibly reduce number of bits an audio signal is sampled
       with. This doesn't change the bit depth at all, it just produces the
       effect. Material reduced in bit depth sounds more harsh and "digital".
       This filter is able to even round to continuous values instead of
       discrete bit depths.  Additionally it has a D/C offset which results in
       different crushing of the lower and the upper half of the signal.  An
       Anti-Aliasing setting is able to produce "softer" crushing sounds.

       Another feature of this filter is the logarithmic mode.	This setting
       switches from linear distances between bits to logarithmic ones.  The
       result is a much more "natural" sounding crusher which doesn't gate low
       signals for example. The human ear has a logarithmic perception, so
       this kind of crushing is much more pleasant.  Logarithmic crushing is
       also able to get anti-aliased.

       The filter accepts the following options:

       level_in
	   Set level in.

       level_out
	   Set level out.

       bits
	   Set bit reduction.

       mix Set mixing amount.

       mode
	   Can be linear: "lin" or logarithmic: "log".

       dc  Set DC.

       aa  Set anti-aliasing.

       samples
	   Set sample reduction.

       lfo Enable LFO. By default disabled.

       lforange
	   Set LFO range.

       lforate
	   Set LFO rate.

   adeclick
       Remove impulsive noise from input audio.

       Samples detected as impulsive noise are replaced by interpolated
       samples using autoregressive modelling.

       w   Set window size, in milliseconds. Allowed range is from 10 to 100.
	   Default value is 55 milliseconds.  This sets size of window which
	   will be processed at once.

       o   Set window overlap, in percentage of window size. Allowed range is
	   from 50 to 95. Default value is 75 percent.	Setting this to a very
	   high value increases impulsive noise removal but makes whole
	   process much slower.

       a   Set autoregression order, in percentage of window size. Allowed
	   range is from 0 to 25. Default value is 2 percent. This option also
	   controls quality of interpolated samples using neighbour good
	   samples.

       t   Set threshold value. Allowed range is from 1 to 100.  Default value
	   is 2.  This controls the strength of impulsive noise which is going
	   to be removed.  The lower value, the more samples will be detected
	   as impulsive noise.

       b   Set burst fusion, in percentage of window size. Allowed range is 0
	   to 10. Default value is 2.  If any two samples deteced as noise are
	   spaced less than this value then any sample inbetween those two
	   samples will be also detected as noise.

       m   Set overlap method.

	   It accepts the following values:

	   a   Select overlap-add method. Even not interpolated samples are
	       slightly changed with this method.

	   s   Select overlap-save method. Not interpolated samples remain
	       unchanged.

	   Default value is "a".

   adeclip
       Remove clipped samples from input audio.

       Samples detected as clipped are replaced by interpolated samples using
       autoregressive modelling.

       w   Set window size, in milliseconds. Allowed range is from 10 to 100.
	   Default value is 55 milliseconds.  This sets size of window which
	   will be processed at once.

       o   Set window overlap, in percentage of window size. Allowed range is
	   from 50 to 95. Default value is 75 percent.

       a   Set autoregression order, in percentage of window size. Allowed
	   range is from 0 to 25. Default value is 8 percent. This option also
	   controls quality of interpolated samples using neighbour good
	   samples.

       t   Set threshold value. Allowed range is from 1 to 100.  Default value
	   is 10. Higher values make clip detection less aggressive.

       n   Set size of histogram used to detect clips. Allowed range is from
	   100 to 9999.  Default value is 1000. Higher values make clip
	   detection less aggressive.

       m   Set overlap method.

	   It accepts the following values:

	   a   Select overlap-add method. Even not interpolated samples are
	       slightly changed with this method.

	   s   Select overlap-save method. Not interpolated samples remain
	       unchanged.

	   Default value is "a".

   adelay
       Delay one or more audio channels.

       Samples in delayed channel are filled with silence.

       The filter accepts the following option:

       delays
	   Set list of delays in milliseconds for each channel separated by
	   '|'.  Unused delays will be silently ignored. If number of given
	   delays is smaller than number of channels all remaining channels
	   will not be delayed.  If you want to delay exact number of samples,
	   append 'S' to number.

       Examples

       ·   Delay first channel by 1.5 seconds, the third channel by 0.5
	   seconds and leave the second channel (and any other channels that
	   may be present) unchanged.

		   adelay=1500|0|500

       ·   Delay second channel by 500 samples, the third channel by 700
	   samples and leave the first channel (and any other channels that
	   may be present) unchanged.

		   adelay=0|500S|700S

   aderivative, aintegral
       Compute derivative/integral of audio stream.

       Applying both filters one after another produces original audio.

   aecho
       Apply echoing to the input audio.

       Echoes are reflected sound and can occur naturally amongst mountains
       (and sometimes large buildings) when talking or shouting; digital echo
       effects emulate this behaviour and are often used to help fill out the
       sound of a single instrument or vocal. The time difference between the
       original signal and the reflection is the "delay", and the loudness of
       the reflected signal is the "decay".  Multiple echoes can have
       different delays and decays.

       A description of the accepted parameters follows.

       in_gain
	   Set input gain of reflected signal. Default is 0.6.

       out_gain
	   Set output gain of reflected signal. Default is 0.3.

       delays
	   Set list of time intervals in milliseconds between original signal
	   and reflections separated by '|'. Allowed range for each "delay" is
	   "(0 - 90000.0]".  Default is 1000.

       decays
	   Set list of loudness of reflected signals separated by '|'.
	   Allowed range for each "decay" is "(0 - 1.0]".  Default is 0.5.

       Examples

       ·   Make it sound as if there are twice as many instruments as are
	   actually playing:

		   aecho=0.8:0.88:60:0.4

       ·   If delay is very short, then it sound like a (metallic) robot
	   playing music:

		   aecho=0.8:0.88:6:0.4

       ·   A longer delay will sound like an open air concert in the
	   mountains:

		   aecho=0.8:0.9:1000:0.3

       ·   Same as above but with one more mountain:

		   aecho=0.8:0.9:1000|1800:0.3|0.25

   aemphasis
       Audio emphasis filter creates or restores material directly taken from
       LPs or emphased CDs with different filter curves. E.g. to store music
       on vinyl the signal has to be altered by a filter first to even out the
       disadvantages of this recording medium.	Once the material is played
       back the inverse filter has to be applied to restore the distortion of
       the frequency response.

       The filter accepts the following options:

       level_in
	   Set input gain.

       level_out
	   Set output gain.

       mode
	   Set filter mode. For restoring material use "reproduction" mode,
	   otherwise use "production" mode. Default is "reproduction" mode.

       type
	   Set filter type. Selects medium. Can be one of the following:

	   col select Columbia.

	   emi select EMI.

	   bsi select BSI (78RPM).

	   riaa
	       select RIAA.

	   cd  select Compact Disc (CD).

	   50fm
	       select 50Xs (FM).

	   75fm
	       select 75Xs (FM).

	   50kf
	       select 50Xs (FM-KF).

	   75kf
	       select 75Xs (FM-KF).

   aeval
       Modify an audio signal according to the specified expressions.

       This filter accepts one or more expressions (one for each channel),
       which are evaluated and used to modify a corresponding audio signal.

       It accepts the following parameters:

       exprs
	   Set the '|'-separated expressions list for each separate channel.
	   If the number of input channels is greater than the number of
	   expressions, the last specified expression is used for the
	   remaining output channels.

       channel_layout, c
	   Set output channel layout. If not specified, the channel layout is
	   specified by the number of expressions. If set to same, it will use
	   by default the same input channel layout.

       Each expression in exprs can contain the following constants and
       functions:

       ch  channel number of the current expression

       n   number of the evaluated sample, starting from 0

       s   sample rate

       t   time of the evaluated sample expressed in seconds

       nb_in_channels
       nb_out_channels
	   input and output number of channels

       val(CH)
	   the value of input channel with number CH

       Note: this filter is slow. For faster processing you should use a
       dedicated filter.

       Examples

       ·   Half volume:

		   aeval=val(ch)/2:c=same

       ·   Invert phase of the second channel:

		   aeval=val(0)|-val(1)

   afade
       Apply fade-in/out effect to input audio.

       A description of the accepted parameters follows.

       type, t
	   Specify the effect type, can be either "in" for fade-in, or "out"
	   for a fade-out effect. Default is "in".

       start_sample, ss
	   Specify the number of the start sample for starting to apply the
	   fade effect. Default is 0.

       nb_samples, ns
	   Specify the number of samples for which the fade effect has to
	   last. At the end of the fade-in effect the output audio will have
	   the same volume as the input audio, at the end of the fade-out
	   transition the output audio will be silence. Default is 44100.

       start_time, st
	   Specify the start time of the fade effect. Default is 0.  The value
	   must be specified as a time duration; see the Time duration section
	   in the ffmpeg-utils(1) manual for the accepted syntax.  If set this
	   option is used instead of start_sample.

       duration, d
	   Specify the duration of the fade effect. See the Time duration
	   section in the ffmpeg-utils(1) manual for the accepted syntax.  At
	   the end of the fade-in effect the output audio will have the same
	   volume as the input audio, at the end of the fade-out transition
	   the output audio will be silence.  By default the duration is
	   determined by nb_samples.  If set this option is used instead of
	   nb_samples.

       curve
	   Set curve for fade transition.

	   It accepts the following values:

	   tri select triangular, linear slope (default)

	   qsin
	       select quarter of sine wave

	   hsin
	       select half of sine wave

	   esin
	       select exponential sine wave

	   log select logarithmic

	   ipar
	       select inverted parabola

	   qua select quadratic

	   cub select cubic

	   squ select square root

	   cbr select cubic root

	   par select parabola

	   exp select exponential

	   iqsin
	       select inverted quarter of sine wave

	   ihsin
	       select inverted half of sine wave

	   dese
	       select double-exponential seat

	   desi
	       select double-exponential sigmoid

       Examples

       ·   Fade in first 15 seconds of audio:

		   afade=t=in:ss=0:d=15

       ·   Fade out last 25 seconds of a 900 seconds audio:

		   afade=t=out:st=875:d=25

   afftfilt
       Apply arbitrary expressions to samples in frequency domain.

       real
	   Set frequency domain real expression for each separate channel
	   separated by '|'. Default is "1".  If the number of input channels
	   is greater than the number of expressions, the last specified
	   expression is used for the remaining output channels.

       imag
	   Set frequency domain imaginary expression for each separate channel
	   separated by '|'. If not set, real option is used.

	   Each expression in real and imag can contain the following
	   constants:

	   sr  sample rate

	   b   current frequency bin number

	   nb  number of available bins

	   ch  channel number of the current expression

	   chs number of channels

	   pts current frame pts

       win_size
	   Set window size.

	   It accepts the following values:

	   w16
	   w32
	   w64
	   w128
	   w256
	   w512
	   w1024
	   w2048
	   w4096
	   w8192
	   w16384
	   w32768
	   w65536

	   Default is "w4096"

       win_func
	   Set window function. Default is "hann".

       overlap
	   Set window overlap. If set to 1, the recommended overlap for
	   selected window function will be picked. Default is 0.75.

       Examples

       ·   Leave almost only low frequencies in audio:

		   afftfilt="1-clip((b/nb)*b,0,1)"

   afir
       Apply an arbitrary Frequency Impulse Response filter.

       This filter is designed for applying long FIR filters, up to 30 seconds
       long.

       It can be used as component for digital crossover filters, room
       equalization, cross talk cancellation, wavefield synthesis,
       auralization, ambiophonics and ambisonics.

       This filter uses second stream as FIR coefficients.  If second stream
       holds single channel, it will be used for all input channels in first
       stream, otherwise number of channels in second stream must be same as
       number of channels in first stream.

       It accepts the following parameters:

       dry Set dry gain. This sets input gain.

       wet Set wet gain. This sets final output gain.

       length
	   Set Impulse Response filter length. Default is 1, which means whole
	   IR is processed.

       again
	   Enable applying gain measured from power of IR.

       maxir
	   Set max allowed Impulse Response filter duration in seconds.
	   Default is 30 seconds.  Allowed range is 0.1 to 60 seconds.

       response
	   Show IR frequency reponse, magnitude and phase in additional video
	   stream.  By default it is disabled.

       channel
	   Set for which IR channel to display frequency response. By default
	   is first channel displayed. This option is used only when response
	   is enabled.

       size
	   Set video stream size. This option is used only when response is
	   enabled.

       Examples

       ·   Apply reverb to stream using mono IR file as second input, complete
	   command using ffmpeg:

		   ffmpeg -i input.wav -i middle_tunnel_1way_mono.wav -lavfi afir output.wav

   aformat
       Set output format constraints for the input audio. The framework will
       negotiate the most appropriate format to minimize conversions.

       It accepts the following parameters:

       sample_fmts
	   A '|'-separated list of requested sample formats.

       sample_rates
	   A '|'-separated list of requested sample rates.

       channel_layouts
	   A '|'-separated list of requested channel layouts.

	   See the Channel Layout section in the ffmpeg-utils(1) manual for
	   the required syntax.

       If a parameter is omitted, all values are allowed.

       Force the output to either unsigned 8-bit or signed 16-bit stereo

	       aformat=sample_fmts=u8|s16:channel_layouts=stereo

   agate
       A gate is mainly used to reduce lower parts of a signal. This kind of
       signal processing reduces disturbing noise between useful signals.

       Gating is done by detecting the volume below a chosen level threshold
       and dividing it by the factor set with ratio. The bottom of the noise
       floor is set via range. Because an exact manipulation of the signal
       would cause distortion of the waveform the reduction can be levelled
       over time. This is done by setting attack and release.

       attack determines how long the signal has to fall below the threshold
       before any reduction will occur and release sets the time the signal
       has to rise above the threshold to reduce the reduction again.  Shorter
       signals than the chosen attack time will be left untouched.

       level_in
	   Set input level before filtering.  Default is 1. Allowed range is
	   from 0.015625 to 64.

       range
	   Set the level of gain reduction when the signal is below the
	   threshold.  Default is 0.06125. Allowed range is from 0 to 1.

       threshold
	   If a signal rises above this level the gain reduction is released.
	   Default is 0.125. Allowed range is from 0 to 1.

       ratio
	   Set a ratio by which the signal is reduced.	Default is 2. Allowed
	   range is from 1 to 9000.

       attack
	   Amount of milliseconds the signal has to rise above the threshold
	   before gain reduction stops.  Default is 20 milliseconds. Allowed
	   range is from 0.01 to 9000.

       release
	   Amount of milliseconds the signal has to fall below the threshold
	   before the reduction is increased again. Default is 250
	   milliseconds.  Allowed range is from 0.01 to 9000.

       makeup
	   Set amount of amplification of signal after processing.  Default is
	   1. Allowed range is from 1 to 64.

       knee
	   Curve the sharp knee around the threshold to enter gain reduction
	   more softly.  Default is 2.828427125. Allowed range is from 1 to 8.

       detection
	   Choose if exact signal should be taken for detection or an RMS like
	   one.  Default is "rms". Can be "peak" or "rms".

       link
	   Choose if the average level between all channels or the louder
	   channel affects the reduction.  Default is "average". Can be
	   "average" or "maximum".

   aiir
       Apply an arbitrary Infinite Impulse Response filter.

       It accepts the following parameters:

       z   Set numerator/zeros coefficients.

       p   Set denominator/poles coefficients.

       k   Set channels gains.

       dry_gain
	   Set input gain.

       wet_gain
	   Set output gain.

       f   Set coefficients format.

	   tf  transfer function

	   zp  Z-plane zeros/poles, cartesian (default)

	   pr  Z-plane zeros/poles, polar radians

	   pd  Z-plane zeros/poles, polar degrees

       r   Set kind of processing.  Can be "d" - direct or "s" - serial
	   cascading. Defauls is "s".

       e   Set filtering precision.

	   dbl double-precision floating-point (default)

	   flt single-precision floating-point

	   i32 32-bit integers

	   i16 16-bit integers

       response
	   Show IR frequency reponse, magnitude and phase in additional video
	   stream.  By default it is disabled.

       channel
	   Set for which IR channel to display frequency response. By default
	   is first channel displayed. This option is used only when response
	   is enabled.

       size
	   Set video stream size. This option is used only when response is
	   enabled.

       Coefficients in "tf" format are separated by spaces and are in
       ascending order.

       Coefficients in "zp" format are separated by spaces and order of
       coefficients doesn't matter. Coefficients in "zp" format are complex
       numbers with i imaginary unit.

       Different coefficients and gains can be provided for every channel, in
       such case use '|' to separate coefficients or gains. Last provided
       coefficients will be used for all remaining channels.

       Examples

       ·   Apply 2 pole elliptic notch at arround 5000Hz for 48000 Hz sample
	   rate:

		   aiir=k=1:z=7.957584807809675810E-1 -2.575128568908332300 3.674839853930788710 -2.57512875289799137 7.957586296317130880E-1:p=1 -2.86950072432325953 3.63022088054647218 -2.28075678147272232 6.361362326477423500E-1:f=tf:r=d

       ·   Same as above but in "zp" format:

		   aiir=k=0.79575848078096756:z=0.80918701+0.58773007i 0.80918701-0.58773007i 0.80884700+0.58784055i 0.80884700-0.58784055i:p=0.63892345+0.59951235i 0.63892345-0.59951235i 0.79582691+0.44198673i 0.79582691-0.44198673i:f=zp:r=s

   alimiter
       The limiter prevents an input signal from rising over a desired
       threshold.  This limiter uses lookahead technology to prevent your
       signal from distorting.	It means that there is a small delay after the
       signal is processed. Keep in mind that the delay it produces is the
       attack time you set.

       The filter accepts the following options:

       level_in
	   Set input gain. Default is 1.

       level_out
	   Set output gain. Default is 1.

       limit
	   Don't let signals above this level pass the limiter. Default is 1.

       attack
	   The limiter will reach its attenuation level in this amount of time
	   in milliseconds. Default is 5 milliseconds.

       release
	   Come back from limiting to attenuation 1.0 in this amount of
	   milliseconds.  Default is 50 milliseconds.

       asc When gain reduction is always needed ASC takes care of releasing to
	   an average reduction level rather than reaching a reduction of 0 in
	   the release time.

       asc_level
	   Select how much the release time is affected by ASC, 0 means nearly
	   no changes in release time while 1 produces higher release times.

       level
	   Auto level output signal. Default is enabled.  This normalizes
	   audio back to 0dB if enabled.

       Depending on picked setting it is recommended to upsample input 2x or
       4x times with aresample before applying this filter.

   allpass
       Apply a two-pole all-pass filter with central frequency (in Hz)
       frequency, and filter-width width.  An all-pass filter changes the
       audio's frequency to phase relationship without changing its frequency
       to amplitude relationship.

       The filter accepts the following options:

       frequency, f
	   Set frequency in Hz.

       width_type, t
	   Set method to specify band-width of filter.

	   h   Hz

	   q   Q-Factor

	   o   octave

	   s   slope

	   k   kHz

       width, w
	   Specify the band-width of a filter in width_type units.

       channels, c
	   Specify which channels to filter, by default all available are
	   filtered.

       Commands

       This filter supports the following commands:

       frequency, f
	   Change allpass frequency.  Syntax for the command is : "frequency"

       width_type, t
	   Change allpass width_type.  Syntax for the command is :
	   "width_type"

       width, w
	   Change allpass width.  Syntax for the command is : "width"

   aloop
       Loop audio samples.

       The filter accepts the following options:

       loop
	   Set the number of loops. Setting this value to -1 will result in
	   infinite loops.  Default is 0.

       size
	   Set maximal number of samples. Default is 0.

       start
	   Set first sample of loop. Default is 0.

   amerge
       Merge two or more audio streams into a single multi-channel stream.

       The filter accepts the following options:

       inputs
	   Set the number of inputs. Default is 2.

       If the channel layouts of the inputs are disjoint, and therefore
       compatible, the channel layout of the output will be set accordingly
       and the channels will be reordered as necessary. If the channel layouts
       of the inputs are not disjoint, the output will have all the channels
       of the first input then all the channels of the second input, in that
       order, and the channel layout of the output will be the default value
       corresponding to the total number of channels.

       For example, if the first input is in 2.1 (FL+FR+LF) and the second
       input is FC+BL+BR, then the output will be in 5.1, with the channels in
       the following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of
       the first input, b1 is the first channel of the second input).

       On the other hand, if both input are in stereo, the output channels
       will be in the default order: a1, a2, b1, b2, and the channel layout
       will be arbitrarily set to 4.0, which may or may not be the expected
       value.

       All inputs must have the same sample rate, and format.

       If inputs do not have the same duration, the output will stop with the
       shortest.

       Examples

       ·   Merge two mono files into a stereo stream:

		   amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge

       ·   Multiple merges assuming 1 video stream and 6 audio streams in
	   input.mkv:

		   ffmpeg -i input.mkv -filter_complex "[0:1][0:2][0:3][0:4][0:5][0:6] amerge=inputs=6" -c:a pcm_s16le output.mkv

   amix
       Mixes multiple audio inputs into a single output.

       Note that this filter only supports float samples (the amerge and pan
       audio filters support many formats). If the amix input has integer
       samples then aresample will be automatically inserted to perform the
       conversion to float samples.

       For example

	       ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT

       will mix 3 input audio streams to a single output with the same
       duration as the first input and a dropout transition time of 3 seconds.

       It accepts the following parameters:

       inputs
	   The number of inputs. If unspecified, it defaults to 2.

       duration
	   How to determine the end-of-stream.

	   longest
	       The duration of the longest input. (default)

	   shortest
	       The duration of the shortest input.

	   first
	       The duration of the first input.

       dropout_transition
	   The transition time, in seconds, for volume renormalization when an
	   input stream ends. The default value is 2 seconds.

       weights
	   Specify weight of each input audio stream as sequence.  Each weight
	   is separated by space. By default all inputs have same weight.

   anequalizer
       High-order parametric multiband equalizer for each channel.

       It accepts the following parameters:

       params
	   This option string is in format: "cchn f=cf w=w g=g t=f | ..."
	   Each equalizer band is separated by '|'.

	   chn Set channel number to which equalization will be applied.  If
	       input doesn't have that channel the entry is ignored.

	   f   Set central frequency for band.	If input doesn't have that
	       frequency the entry is ignored.

	   w   Set band width in hertz.

	   g   Set band gain in dB.

	   t   Set filter type for band, optional, can be:

	       0   Butterworth, this is default.

	       1   Chebyshev type 1.

	       2   Chebyshev type 2.

       curves
	   With this option activated frequency response of anequalizer is
	   displayed in video stream.

       size
	   Set video stream size. Only useful if curves option is activated.

       mgain
	   Set max gain that will be displayed. Only useful if curves option
	   is activated.  Setting this to a reasonable value makes it possible
	   to display gain which is derived from neighbour bands which are too
	   close to each other and thus produce higher gain when both are
	   activated.

       fscale
	   Set frequency scale used to draw frequency response in video
	   output.  Can be linear or logarithmic. Default is logarithmic.

       colors
	   Set color for each channel curve which is going to be displayed in
	   video stream.  This is list of color names separated by space or by
	   '|'.  Unrecognised or missing colors will be replaced by white
	   color.

       Examples

       ·   Lower gain by 10 of central frequency 200Hz and width 100 Hz for
	   first 2 channels using Chebyshev type 1 filter:

		   anequalizer=c0 f=200 w=100 g=-10 t=1|c1 f=200 w=100 g=-10 t=1

       Commands

       This filter supports the following commands:

       change
	   Alter existing filter parameters.  Syntax for the commands is :
	   "fN|f=freq|w=width|g=gain"

	   fN is existing filter number, starting from 0, if no such filter is
	   available error is returned.  freq set new frequency parameter.
	   width set new width parameter in herz.  gain set new gain parameter
	   in dB.

	   Full filter invocation with asendcmd may look like this:
	   asendcmd=c='4.0 anequalizer change
	   0|f=200|w=50|g=1',anequalizer=...

   anull
       Pass the audio source unchanged to the output.

   apad
       Pad the end of an audio stream with silence.

       This can be used together with ffmpeg -shortest to extend audio streams
       to the same length as the video stream.

       A description of the accepted options follows.

       packet_size
	   Set silence packet size. Default value is 4096.

       pad_len
	   Set the number of samples of silence to add to the end. After the
	   value is reached, the stream is terminated. This option is mutually
	   exclusive with whole_len.

       whole_len
	   Set the minimum total number of samples in the output audio stream.
	   If the value is longer than the input audio length, silence is
	   added to the end, until the value is reached. This option is
	   mutually exclusive with pad_len.

       If neither the pad_len nor the whole_len option is set, the filter will
       add silence to the end of the input stream indefinitely.

       Examples

       ·   Add 1024 samples of silence to the end of the input:

		   apad=pad_len=1024

       ·   Make sure the audio output will contain at least 10000 samples, pad
	   the input with silence if required:

		   apad=whole_len=10000

       ·   Use ffmpeg to pad the audio input with silence, so that the video
	   stream will always result the shortest and will be converted until
	   the end in the output file when using the shortest option:

		   ffmpeg -i VIDEO -i AUDIO -filter_complex "[1:0]apad" -shortest OUTPUT

   aphaser
       Add a phasing effect to the input audio.

       A phaser filter creates series of peaks and troughs in the frequency
       spectrum.  The position of the peaks and troughs are modulated so that
       they vary over time, creating a sweeping effect.

       A description of the accepted parameters follows.

       in_gain
	   Set input gain. Default is 0.4.

       out_gain
	   Set output gain. Default is 0.74

       delay
	   Set delay in milliseconds. Default is 3.0.

       decay
	   Set decay. Default is 0.4.

       speed
	   Set modulation speed in Hz. Default is 0.5.

       type
	   Set modulation type. Default is triangular.

	   It accepts the following values:

	   triangular, t
	   sinusoidal, s

   apulsator
       Audio pulsator is something between an autopanner and a tremolo.  But
       it can produce funny stereo effects as well. Pulsator changes the
       volume of the left and right channel based on a LFO (low frequency
       oscillator) with different waveforms and shifted phases.  This filter
       have the ability to define an offset between left and right channel. An
       offset of 0 means that both LFO shapes match each other.  The left and
       right channel are altered equally - a conventional tremolo.  An offset
       of 50% means that the shape of the right channel is exactly shifted in
       phase (or moved backwards about half of the frequency) - pulsator acts
       as an autopanner. At 1 both curves match again. Every setting in
       between moves the phase shift gapless between all stages and produces
       some "bypassing" sounds with sine and triangle waveforms. The more you
       set the offset near 1 (starting from the 0.5) the faster the signal
       passes from the left to the right speaker.

       The filter accepts the following options:

       level_in
	   Set input gain. By default it is 1. Range is [0.015625 - 64].

       level_out
	   Set output gain. By default it is 1. Range is [0.015625 - 64].

       mode
	   Set waveform shape the LFO will use. Can be one of: sine, triangle,
	   square, sawup or sawdown. Default is sine.

       amount
	   Set modulation. Define how much of original signal is affected by
	   the LFO.

       offset_l
	   Set left channel offset. Default is 0. Allowed range is [0 - 1].

       offset_r
	   Set right channel offset. Default is 0.5. Allowed range is [0 - 1].

       width
	   Set pulse width. Default is 1. Allowed range is [0 - 2].

       timing
	   Set possible timing mode. Can be one of: bpm, ms or hz. Default is
	   hz.

       bpm Set bpm. Default is 120. Allowed range is [30 - 300]. Only used if
	   timing is set to bpm.

       ms  Set ms. Default is 500. Allowed range is [10 - 2000]. Only used if
	   timing is set to ms.

       hz  Set frequency in Hz. Default is 2. Allowed range is [0.01 - 100].
	   Only used if timing is set to hz.

   aresample
       Resample the input audio to the specified parameters, using the
       libswresample library. If none are specified then the filter will
       automatically convert between its input and output.

       This filter is also able to stretch/squeeze the audio data to make it
       match the timestamps or to inject silence / cut out audio to make it
       match the timestamps, do a combination of both or do neither.

       The filter accepts the syntax [sample_rate:]resampler_options, where
       sample_rate expresses a sample rate and resampler_options is a list of
       key=value pairs, separated by ":". See the "Resampler Options" section
       in the ffmpeg-resampler(1) manual for the complete list of supported
       options.

       Examples

       ·   Resample the input audio to 44100Hz:

		   aresample=44100

       ·   Stretch/squeeze samples to the given timestamps, with a maximum of
	   1000 samples per second compensation:

		   aresample=async=1000

   areverse
       Reverse an audio clip.

       Warning: This filter requires memory to buffer the entire clip, so
       trimming is suggested.

       Examples

       ·   Take the first 5 seconds of a clip, and reverse it.

		   atrim=end=5,areverse

   asetnsamples
       Set the number of samples per each output audio frame.

       The last output packet may contain a different number of samples, as
       the filter will flush all the remaining samples when the input audio
       signals its end.

       The filter accepts the following options:

       nb_out_samples, n
	   Set the number of frames per each output audio frame. The number is
	   intended as the number of samples per each channel.	Default value
	   is 1024.

       pad, p
	   If set to 1, the filter will pad the last audio frame with zeroes,
	   so that the last frame will contain the same number of samples as
	   the previous ones. Default value is 1.

       For example, to set the number of per-frame samples to 1234 and disable
       padding for the last frame, use:

	       asetnsamples=n=1234:p=0

   asetrate
       Set the sample rate without altering the PCM data.  This will result in
       a change of speed and pitch.

       The filter accepts the following options:

       sample_rate, r
	   Set the output sample rate. Default is 44100 Hz.

   ashowinfo
       Show a line containing various information for each input audio frame.
       The input audio is not modified.

       The shown line contains a sequence of key/value pairs of the form
       key:value.

       The following values are shown in the output:

       n   The (sequential) number of the input frame, starting from 0.

       pts The presentation timestamp of the input frame, in time base units;
	   the time base depends on the filter input pad, and is usually
	   1/sample_rate.

       pts_time
	   The presentation timestamp of the input frame in seconds.

       pos position of the frame in the input stream, -1 if this information
	   in unavailable and/or meaningless (for example in case of synthetic
	   audio)

       fmt The sample format.

       chlayout
	   The channel layout.

       rate
	   The sample rate for the audio frame.

       nb_samples
	   The number of samples (per channel) in the frame.

       checksum
	   The Adler-32 checksum (printed in hexadecimal) of the audio data.
	   For planar audio, the data is treated as if all the planes were
	   concatenated.

       plane_checksums
	   A list of Adler-32 checksums for each data plane.

   astats
       Display time domain statistical information about the audio channels.
       Statistics are calculated and displayed for each audio channel and,
       where applicable, an overall figure is also given.

       It accepts the following option:

       length
	   Short window length in seconds, used for peak and trough RMS
	   measurement.  Default is 0.05 (50 milliseconds). Allowed range is
	   "[0.01 - 10]".

       metadata
	   Set metadata injection. All the metadata keys are prefixed with
	   "lavfi.astats.X", where "X" is channel number starting from 1 or
	   string "Overall". Default is disabled.

	   Available keys for each channel are: DC_offset Min_level Max_level
	   Min_difference Max_difference Mean_difference RMS_difference
	   Peak_level RMS_peak RMS_trough Crest_factor Flat_factor Peak_count
	   Bit_depth Dynamic_range

	   and for Overall: DC_offset Min_level Max_level Min_difference
	   Max_difference Mean_difference RMS_difference Peak_level RMS_level
	   RMS_peak RMS_trough Flat_factor Peak_count Bit_depth
	   Number_of_samples

	   For example full key look like this "lavfi.astats.1.DC_offset" or
	   this "lavfi.astats.Overall.Peak_count".

	   For description what each key means read below.

       reset
	   Set number of frame after which stats are going to be recalculated.
	   Default is disabled.

       A description of each shown parameter follows:

       DC offset
	   Mean amplitude displacement from zero.

       Min level
	   Minimal sample level.

       Max level
	   Maximal sample level.

       Min difference
	   Minimal difference between two consecutive samples.

       Max difference
	   Maximal difference between two consecutive samples.

       Mean difference
	   Mean difference between two consecutive samples.  The average of
	   each difference between two consecutive samples.

       RMS difference
	   Root Mean Square difference between two consecutive samples.

       Peak level dB
       RMS level dB
	   Standard peak and RMS level measured in dBFS.

       RMS peak dB
       RMS trough dB
	   Peak and trough values for RMS level measured over a short window.

       Crest factor
	   Standard ratio of peak to RMS level (note: not in dB).

       Flat factor
	   Flatness (i.e. consecutive samples with the same value) of the
	   signal at its peak levels (i.e. either Min level or Max level).

       Peak count
	   Number of occasions (not the number of samples) that the signal
	   attained either Min level or Max level.

       Bit depth
	   Overall bit depth of audio. Number of bits used for each sample.

       Dynamic range
	   Measured dynamic range of audio in dB.

   atempo
       Adjust audio tempo.

       The filter accepts exactly one parameter, the audio tempo. If not
       specified then the filter will assume nominal 1.0 tempo. Tempo must be
       in the [0.5, 100.0] range.

       Note that tempo greater than 2 will skip some samples rather than blend
       them in.  If for any reason this is a concern it is always possible to
       daisy-chain several instances of atempo to achieve the desired product
       tempo.

       Examples

       ·   Slow down audio to 80% tempo:

		   atempo=0.8

       ·   To speed up audio to 300% tempo:

		   atempo=3

       ·   To speed up audio to 300% tempo by daisy-chaining two atempo
	   instances:

		   atempo=sqrt(3),atempo=sqrt(3)

   atrim
       Trim the input so that the output contains one continuous subpart of
       the input.

       It accepts the following parameters:

       start
	   Timestamp (in seconds) of the start of the section to keep. I.e.
	   the audio sample with the timestamp start will be the first sample
	   in the output.

       end Specify time of the first audio sample that will be dropped, i.e.
	   the audio sample immediately preceding the one with the timestamp
	   end will be the last sample in the output.

       start_pts
	   Same as start, except this option sets the start timestamp in
	   samples instead of seconds.

       end_pts
	   Same as end, except this option sets the end timestamp in samples
	   instead of seconds.

       duration
	   The maximum duration of the output in seconds.

       start_sample
	   The number of the first sample that should be output.

       end_sample
	   The number of the first sample that should be dropped.

       start, end, and duration are expressed as time duration specifications;
       see the Time duration section in the ffmpeg-utils(1) manual.

       Note that the first two sets of the start/end options and the duration
       option look at the frame timestamp, while the _sample options simply
       count the samples that pass through the filter. So start/end_pts and
       start/end_sample will give different results when the timestamps are
       wrong, inexact or do not start at zero. Also note that this filter does
       not modify the timestamps. If you wish to have the output timestamps
       start at zero, insert the asetpts filter after the atrim filter.

       If multiple start or end options are set, this filter tries to be
       greedy and keep all samples that match at least one of the specified
       constraints. To keep only the part that matches all the constraints at
       once, chain multiple atrim filters.

       The defaults are such that all the input is kept. So it is possible to
       set e.g.  just the end values to keep everything before the specified
       time.

       Examples:

       ·   Drop everything except the second minute of input:

		   ffmpeg -i INPUT -af atrim=60:120

       ·   Keep only the first 1000 samples:

		   ffmpeg -i INPUT -af atrim=end_sample=1000

   bandpass
       Apply a two-pole Butterworth band-pass filter with central frequency
       frequency, and (3dB-point) band-width width.  The csg option selects a
       constant skirt gain (peak gain = Q) instead of the default: constant
       0dB peak gain.  The filter roll off at 6dB per octave (20dB per
       decade).

       The filter accepts the following options:

       frequency, f
	   Set the filter's central frequency. Default is 3000.

       csg Constant skirt gain if set to 1. Defaults to 0.

       width_type, t
	   Set method to specify band-width of filter.

	   h   Hz

	   q   Q-Factor

	   o   octave

	   s   slope

	   k   kHz

       width, w
	   Specify the band-width of a filter in width_type units.

       channels, c
	   Specify which channels to filter, by default all available are
	   filtered.

       Commands

       This filter supports the following commands:

       frequency, f
	   Change bandpass frequency.  Syntax for the command is : "frequency"

       width_type, t
	   Change bandpass width_type.	Syntax for the command is :
	   "width_type"

       width, w
	   Change bandpass width.  Syntax for the command is : "width"

   bandreject
       Apply a two-pole Butterworth band-reject filter with central frequency
       frequency, and (3dB-point) band-width width.  The filter roll off at
       6dB per octave (20dB per decade).

       The filter accepts the following options:

       frequency, f
	   Set the filter's central frequency. Default is 3000.

       width_type, t
	   Set method to specify band-width of filter.

	   h   Hz

	   q   Q-Factor

	   o   octave

	   s   slope

	   k   kHz

       width, w
	   Specify the band-width of a filter in width_type units.

       channels, c
	   Specify which channels to filter, by default all available are
	   filtered.

       Commands

       This filter supports the following commands:

       frequency, f
	   Change bandreject frequency.  Syntax for the command is :
	   "frequency"

       width_type, t
	   Change bandreject width_type.  Syntax for the command is :
	   "width_type"

       width, w
	   Change bandreject width.  Syntax for the command is : "width"

   bass, lowshelf
       Boost or cut the bass (lower) frequencies of the audio using a two-pole
       shelving filter with a response similar to that of a standard hi-fi's
       tone-controls. This is also known as shelving equalisation (EQ).

       The filter accepts the following options:

       gain, g
	   Give the gain at 0 Hz. Its useful range is about -20 (for a large
	   cut) to +20 (for a large boost).  Beware of clipping when using a
	   positive gain.

       frequency, f
	   Set the filter's central frequency and so can be used to extend or
	   reduce the frequency range to be boosted or cut.  The default value
	   is 100 Hz.

       width_type, t
	   Set method to specify band-width of filter.

	   h   Hz

	   q   Q-Factor

	   o   octave

	   s   slope

	   k   kHz

       width, w
	   Determine how steep is the filter's shelf transition.

       channels, c
	   Specify which channels to filter, by default all available are
	   filtered.

       Commands

       This filter supports the following commands:

       frequency, f
	   Change bass frequency.  Syntax for the command is : "frequency"

       width_type, t
	   Change bass width_type.  Syntax for the command is : "width_type"

       width, w
	   Change bass width.  Syntax for the command is : "width"

       gain, g
	   Change bass gain.  Syntax for the command is : "gain"

   biquad
       Apply a biquad IIR filter with the given coefficients.  Where b0, b1,
       b2 and a0, a1, a2 are the numerator and denominator coefficients
       respectively.  and channels, c specify which channels to filter, by
       default all available are filtered.

       Commands

       This filter supports the following commands:

       a0
       a1
       a2
       b0
       b1
       b2  Change biquad parameter.  Syntax for the command is : "value"

   bs2b
       Bauer stereo to binaural transformation, which improves headphone
       listening of stereo audio records.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-libbs2b".

       It accepts the following parameters:

       profile
	   Pre-defined crossfeed level.

	   default
	       Default level (fcut=700, feed=50).

	   cmoy
	       Chu Moy circuit (fcut=700, feed=60).

	   jmeier
	       Jan Meier circuit (fcut=650, feed=95).

       fcut
	   Cut frequency (in Hz).

       feed
	   Feed level (in Hz).

   channelmap
       Remap input channels to new locations.

       It accepts the following parameters:

       map Map channels from input to output. The argument is a '|'-separated
	   list of mappings, each in the "in_channel-out_channel" or
	   in_channel form. in_channel can be either the name of the input
	   channel (e.g. FL for front left) or its index in the input channel
	   layout.  out_channel is the name of the output channel or its index
	   in the output channel layout. If out_channel is not given then it
	   is implicitly an index, starting with zero and increasing by one
	   for each mapping.

       channel_layout
	   The channel layout of the output stream.

       If no mapping is present, the filter will implicitly map input channels
       to output channels, preserving indices.

       Examples

       ·   For example, assuming a 5.1+downmix input MOV file,

		   ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav

	   will create an output WAV file tagged as stereo from the downmix
	   channels of the input.

       ·   To fix a 5.1 WAV improperly encoded in AAC's native channel order

		   ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:5.1' out.wav

   channelsplit
       Split each channel from an input audio stream into a separate output
       stream.

       It accepts the following parameters:

       channel_layout
	   The channel layout of the input stream. The default is "stereo".

       channels
	   A channel layout describing the channels to be extracted as
	   separate output streams or "all" to extract each input channel as a
	   separate stream. The default is "all".

	   Choosing channels not present in channel layout in the input will
	   result in an error.

       Examples

       ·   For example, assuming a stereo input MP3 file,

		   ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv

	   will create an output Matroska file with two audio streams, one
	   containing only the left channel and the other the right channel.

       ·   Split a 5.1 WAV file into per-channel files:

		   ffmpeg -i in.wav -filter_complex
		   'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
		   -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
		   front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
		   side_right.wav

       ·   Extract only LFE from a 5.1 WAV file:

		   ffmpeg -i in.wav -filter_complex 'channelsplit=channel_layout=5.1:channels=LFE[LFE]'
		   -map '[LFE]' lfe.wav

   chorus
       Add a chorus effect to the audio.

       Can make a single vocal sound like a chorus, but can also be applied to
       instrumentation.

       Chorus resembles an echo effect with a short delay, but whereas with
       echo the delay is constant, with chorus, it is varied using using
       sinusoidal or triangular modulation.  The modulation depth defines the
       range the modulated delay is played before or after the delay. Hence
       the delayed sound will sound slower or faster, that is the delayed
       sound tuned around the original one, like in a chorus where some vocals
       are slightly off key.

       It accepts the following parameters:

       in_gain
	   Set input gain. Default is 0.4.

       out_gain
	   Set output gain. Default is 0.4.

       delays
	   Set delays. A typical delay is around 40ms to 60ms.

       decays
	   Set decays.

       speeds
	   Set speeds.

       depths
	   Set depths.

       Examples

       ·   A single delay:

		   chorus=0.7:0.9:55:0.4:0.25:2

       ·   Two delays:

		   chorus=0.6:0.9:50|60:0.4|0.32:0.25|0.4:2|1.3

       ·   Fuller sounding chorus with three delays:

		   chorus=0.5:0.9:50|60|40:0.4|0.32|0.3:0.25|0.4|0.3:2|2.3|1.3

   compand
       Compress or expand the audio's dynamic range.

       It accepts the following parameters:

       attacks
       decays
	   A list of times in seconds for each channel over which the
	   instantaneous level of the input signal is averaged to determine
	   its volume. attacks refers to increase of volume and decays refers
	   to decrease of volume. For most situations, the attack time
	   (response to the audio getting louder) should be shorter than the
	   decay time, because the human ear is more sensitive to sudden loud
	   audio than sudden soft audio. A typical value for attack is 0.3
	   seconds and a typical value for decay is 0.8 seconds.  If specified
	   number of attacks & decays is lower than number of channels, the
	   last set attack/decay will be used for all remaining channels.

       points
	   A list of points for the transfer function, specified in dB
	   relative to the maximum possible signal amplitude. Each key points
	   list must be defined using the following syntax:
	   "x0/y0|x1/y1|x2/y2|...." or "x0/y0 x1/y1 x2/y2 ...."

	   The input values must be in strictly increasing order but the
	   transfer function does not have to be monotonically rising. The
	   point "0/0" is assumed but may be overridden (by "0/out-dBn").
	   Typical values for the transfer function are "-70/-70|-60/-20|1/0".

       soft-knee
	   Set the curve radius in dB for all joints. It defaults to 0.01.

       gain
	   Set the additional gain in dB to be applied at all points on the
	   transfer function. This allows for easy adjustment of the overall
	   gain.  It defaults to 0.

       volume
	   Set an initial volume, in dB, to be assumed for each channel when
	   filtering starts. This permits the user to supply a nominal level
	   initially, so that, for example, a very large gain is not applied
	   to initial signal levels before the companding has begun to
	   operate. A typical value for audio which is initially quiet is -90
	   dB. It defaults to 0.

       delay
	   Set a delay, in seconds. The input audio is analyzed immediately,
	   but audio is delayed before being fed to the volume adjuster.
	   Specifying a delay approximately equal to the attack/decay times
	   allows the filter to effectively operate in predictive rather than
	   reactive mode. It defaults to 0.

       Examples

       ·   Make music with both quiet and loud passages suitable for listening
	   to in a noisy environment:

		   compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2

	   Another example for audio with whisper and explosion parts:

		   compand=0|0:1|1:-90/-900|-70/-70|-30/-9|0/-3:6:0:0:0

       ·   A noise gate for when the noise is at a lower level than the
	   signal:

		   compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1

       ·   Here is another noise gate, this time for when the noise is at a
	   higher level than the signal (making it, in some ways, similar to
	   squelch):

		   compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1

       ·   2:1 compression starting at -6dB:

		   compand=points=-80/-80|-6/-6|0/-3.8|20/3.5

       ·   2:1 compression starting at -9dB:

		   compand=points=-80/-80|-9/-9|0/-5.3|20/2.9

       ·   2:1 compression starting at -12dB:

		   compand=points=-80/-80|-12/-12|0/-6.8|20/1.9

       ·   2:1 compression starting at -18dB:

		   compand=points=-80/-80|-18/-18|0/-9.8|20/0.7

       ·   3:1 compression starting at -15dB:

		   compand=points=-80/-80|-15/-15|0/-10.8|20/-5.2

       ·   Compressor/Gate:

		   compand=points=-80/-105|-62/-80|-15.4/-15.4|0/-12|20/-7.6

       ·   Expander:

		   compand=attacks=0:points=-80/-169|-54/-80|-49.5/-64.6|-41.1/-41.1|-25.8/-15|-10.8/-4.5|0/0|20/8.3

       ·   Hard limiter at -6dB:

		   compand=attacks=0:points=-80/-80|-6/-6|20/-6

       ·   Hard limiter at -12dB:

		   compand=attacks=0:points=-80/-80|-12/-12|20/-12

       ·   Hard noise gate at -35 dB:

		   compand=attacks=0:points=-80/-115|-35.1/-80|-35/-35|20/20

       ·   Soft limiter:

		   compand=attacks=0:points=-80/-80|-12.4/-12.4|-6/-8|0/-6.8|20/-2.8

   compensationdelay
       Compensation Delay Line is a metric based delay to compensate differing
       positions of microphones or speakers.

       For example, you have recorded guitar with two microphones placed in
       different location. Because the front of sound wave has fixed speed in
       normal conditions, the phasing of microphones can vary and depends on
       their location and interposition. The best sound mix can be achieved
       when these microphones are in phase (synchronized). Note that distance
       of ~30 cm between microphones makes one microphone to capture signal in
       antiphase to another microphone. That makes the final mix sounding
       moody.  This filter helps to solve phasing problems by adding different
       delays to each microphone track and make them synchronized.

       The best result can be reached when you take one track as base and
       synchronize other tracks one by one with it.  Remember that
       synchronization/delay tolerance depends on sample rate, too.  Higher
       sample rates will give more tolerance.

       It accepts the following parameters:

       mm  Set millimeters distance. This is compensation distance for fine
	   tuning.  Default is 0.

       cm  Set cm distance. This is compensation distance for tightening
	   distance setup.  Default is 0.

       m   Set meters distance. This is compensation distance for hard
	   distance setup.  Default is 0.

       dry Set dry amount. Amount of unprocessed (dry) signal.	Default is 0.

       wet Set wet amount. Amount of processed (wet) signal.  Default is 1.

       temp
	   Set temperature degree in Celsius. This is the temperature of the
	   environment.  Default is 20.

   crossfeed
       Apply headphone crossfeed filter.

       Crossfeed is the process of blending the left and right channels of
       stereo audio recording.	It is mainly used to reduce extreme stereo
       separation of low frequencies.

       The intent is to produce more speaker like sound to the listener.

       The filter accepts the following options:

       strength
	   Set strength of crossfeed. Default is 0.2. Allowed range is from 0
	   to 1.  This sets gain of low shelf filter for side part of stereo
	   image.  Default is -6dB. Max allowed is -30db when strength is set
	   to 1.

       range
	   Set soundstage wideness. Default is 0.5. Allowed range is from 0 to
	   1.  This sets cut off frequency of low shelf filter. Default is cut
	   off near 1550 Hz. With range set to 1 cut off frequency is set to
	   2100 Hz.

       level_in
	   Set input gain. Default is 0.9.

       level_out
	   Set output gain. Default is 1.

   crystalizer
       Simple algorithm to expand audio dynamic range.

       The filter accepts the following options:

       i   Sets the intensity of effect (default: 2.0). Must be in range
	   between 0.0 (unchanged sound) to 10.0 (maximum effect).

       c   Enable clipping. By default is enabled.

   dcshift
       Apply a DC shift to the audio.

       This can be useful to remove a DC offset (caused perhaps by a hardware
       problem in the recording chain) from the audio. The effect of a DC
       offset is reduced headroom and hence volume. The astats filter can be
       used to determine if a signal has a DC offset.

       shift
	   Set the DC shift, allowed range is [-1, 1]. It indicates the amount
	   to shift the audio.

       limitergain
	   Optional. It should have a value much less than 1 (e.g. 0.05 or
	   0.02) and is used to prevent clipping.

   drmeter
       Measure audio dynamic range.

       DR values of 14 and higher is found in very dynamic material. DR of 8
       to 13 is found in transition material. And anything less that 8 have
       very poor dynamics and is very compressed.

       The filter accepts the following options:

       length
	   Set window length in seconds used to split audio into segments of
	   equal length.  Default is 3 seconds.

   dynaudnorm
       Dynamic Audio Normalizer.

       This filter applies a certain amount of gain to the input audio in
       order to bring its peak magnitude to a target level (e.g. 0 dBFS).
       However, in contrast to more "simple" normalization algorithms, the
       Dynamic Audio Normalizer *dynamically* re-adjusts the gain factor to
       the input audio.  This allows for applying extra gain to the "quiet"
       sections of the audio while avoiding distortions or clipping the "loud"
       sections. In other words: The Dynamic Audio Normalizer will "even out"
       the volume of quiet and loud sections, in the sense that the volume of
       each section is brought to the same target level. Note, however, that
       the Dynamic Audio Normalizer achieves this goal *without* applying
       "dynamic range compressing". It will retain 100% of the dynamic range
       *within* each section of the audio file.

       f   Set the frame length in milliseconds. In range from 10 to 8000
	   milliseconds.  Default is 500 milliseconds.	The Dynamic Audio
	   Normalizer processes the input audio in small chunks, referred to
	   as frames. This is required, because a peak magnitude has no
	   meaning for just a single sample value. Instead, we need to
	   determine the peak magnitude for a contiguous sequence of sample
	   values. While a "standard" normalizer would simply use the peak
	   magnitude of the complete file, the Dynamic Audio Normalizer
	   determines the peak magnitude individually for each frame. The
	   length of a frame is specified in milliseconds. By default, the
	   Dynamic Audio Normalizer uses a frame length of 500 milliseconds,
	   which has been found to give good results with most files.  Note
	   that the exact frame length, in number of samples, will be
	   determined automatically, based on the sampling rate of the
	   individual input audio file.

       g   Set the Gaussian filter window size. In range from 3 to 301, must
	   be odd number. Default is 31.  Probably the most important
	   parameter of the Dynamic Audio Normalizer is the "window size" of
	   the Gaussian smoothing filter. The filter's window size is
	   specified in frames, centered around the current frame. For the
	   sake of simplicity, this must be an odd number. Consequently, the
	   default value of 31 takes into account the current frame, as well
	   as the 15 preceding frames and the 15 subsequent frames. Using a
	   larger window results in a stronger smoothing effect and thus in
	   less gain variation, i.e. slower gain adaptation. Conversely, using
	   a smaller window results in a weaker smoothing effect and thus in
	   more gain variation, i.e. faster gain adaptation.  In other words,
	   the more you increase this value, the more the Dynamic Audio
	   Normalizer will behave like a "traditional" normalization filter.
	   On the contrary, the more you decrease this value, the more the
	   Dynamic Audio Normalizer will behave like a dynamic range
	   compressor.

       p   Set the target peak value. This specifies the highest permissible
	   magnitude level for the normalized audio input. This filter will
	   try to approach the target peak magnitude as closely as possible,
	   but at the same time it also makes sure that the normalized signal
	   will never exceed the peak magnitude.  A frame's maximum local gain
	   factor is imposed directly by the target peak magnitude. The
	   default value is 0.95 and thus leaves a headroom of 5%*.  It is not
	   recommended to go above this value.

       m   Set the maximum gain factor. In range from 1.0 to 100.0. Default is
	   10.0.  The Dynamic Audio Normalizer determines the maximum possible
	   (local) gain factor for each input frame, i.e. the maximum gain
	   factor that does not result in clipping or distortion. The maximum
	   gain factor is determined by the frame's highest magnitude sample.
	   However, the Dynamic Audio Normalizer additionally bounds the
	   frame's maximum gain factor by a predetermined (global) maximum
	   gain factor. This is done in order to avoid excessive gain factors
	   in "silent" or almost silent frames. By default, the maximum gain
	   factor is 10.0, For most inputs the default value should be
	   sufficient and it usually is not recommended to increase this
	   value. Though, for input with an extremely low overall volume
	   level, it may be necessary to allow even higher gain factors. Note,
	   however, that the Dynamic Audio Normalizer does not simply apply a
	   "hard" threshold (i.e. cut off values above the threshold).
	   Instead, a "sigmoid" threshold function will be applied. This way,
	   the gain factors will smoothly approach the threshold value, but
	   never exceed that value.

       r   Set the target RMS. In range from 0.0 to 1.0. Default is 0.0 -
	   disabled.  By default, the Dynamic Audio Normalizer performs "peak"
	   normalization.  This means that the maximum local gain factor for
	   each frame is defined (only) by the frame's highest magnitude
	   sample. This way, the samples can be amplified as much as possible
	   without exceeding the maximum signal level, i.e. without clipping.
	   Optionally, however, the Dynamic Audio Normalizer can also take
	   into account the frame's root mean square, abbreviated RMS. In
	   electrical engineering, the RMS is commonly used to determine the
	   power of a time-varying signal. It is therefore considered that the
	   RMS is a better approximation of the "perceived loudness" than just
	   looking at the signal's peak magnitude. Consequently, by adjusting
	   all frames to a constant RMS value, a uniform "perceived loudness"
	   can be established. If a target RMS value has been specified, a
	   frame's local gain factor is defined as the factor that would
	   result in exactly that RMS value.  Note, however, that the maximum
	   local gain factor is still restricted by the frame's highest
	   magnitude sample, in order to prevent clipping.

       n   Enable channels coupling. By default is enabled.  By default, the
	   Dynamic Audio Normalizer will amplify all channels by the same
	   amount. This means the same gain factor will be applied to all
	   channels, i.e.  the maximum possible gain factor is determined by
	   the "loudest" channel.  However, in some recordings, it may happen
	   that the volume of the different channels is uneven, e.g. one
	   channel may be "quieter" than the other one(s).  In this case, this
	   option can be used to disable the channel coupling. This way, the
	   gain factor will be determined independently for each channel,
	   depending only on the individual channel's highest magnitude
	   sample. This allows for harmonizing the volume of the different
	   channels.

       c   Enable DC bias correction. By default is disabled.  An audio signal
	   (in the time domain) is a sequence of sample values.  In the
	   Dynamic Audio Normalizer these sample values are represented in the
	   -1.0 to 1.0 range, regardless of the original input format.
	   Normally, the audio signal, or "waveform", should be centered
	   around the zero point.  That means if we calculate the mean value
	   of all samples in a file, or in a single frame, then the result
	   should be 0.0 or at least very close to that value. If, however,
	   there is a significant deviation of the mean value from 0.0, in
	   either positive or negative direction, this is referred to as a DC
	   bias or DC offset. Since a DC bias is clearly undesirable, the
	   Dynamic Audio Normalizer provides optional DC bias correction.
	   With DC bias correction enabled, the Dynamic Audio Normalizer will
	   determine the mean value, or "DC correction" offset, of each input
	   frame and subtract that value from all of the frame's sample values
	   which ensures those samples are centered around 0.0 again. Also, in
	   order to avoid "gaps" at the frame boundaries, the DC correction
	   offset values will be interpolated smoothly between neighbouring
	   frames.

       b   Enable alternative boundary mode. By default is disabled.  The
	   Dynamic Audio Normalizer takes into account a certain neighbourhood
	   around each frame. This includes the preceding frames as well as
	   the subsequent frames. However, for the "boundary" frames, located
	   at the very beginning and at the very end of the audio file, not
	   all neighbouring frames are available. In particular, for the first
	   few frames in the audio file, the preceding frames are not known.
	   And, similarly, for the last few frames in the audio file, the
	   subsequent frames are not known. Thus, the question arises which
	   gain factors should be assumed for the missing frames in the
	   "boundary" region. The Dynamic Audio Normalizer implements two
	   modes to deal with this situation. The default boundary mode
	   assumes a gain factor of exactly 1.0 for the missing frames,
	   resulting in a smooth "fade in" and "fade out" at the beginning and
	   at the end of the input, respectively.

       s   Set the compress factor. In range from 0.0 to 30.0. Default is 0.0.
	   By default, the Dynamic Audio Normalizer does not apply
	   "traditional" compression. This means that signal peaks will not be
	   pruned and thus the full dynamic range will be retained within each
	   local neighbourhood. However, in some cases it may be desirable to
	   combine the Dynamic Audio Normalizer's normalization algorithm with
	   a more "traditional" compression.  For this purpose, the Dynamic
	   Audio Normalizer provides an optional compression (thresholding)
	   function. If (and only if) the compression feature is enabled, all
	   input frames will be processed by a soft knee thresholding function
	   prior to the actual normalization process. Put simply, the
	   thresholding function is going to prune all samples whose magnitude
	   exceeds a certain threshold value.  However, the Dynamic Audio
	   Normalizer does not simply apply a fixed threshold value. Instead,
	   the threshold value will be adjusted for each individual frame.  In
	   general, smaller parameters result in stronger compression, and
	   vice versa.	Values below 3.0 are not recommended, because audible
	   distortion may appear.

   earwax
       Make audio easier to listen to on headphones.

       This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
       so that when listened to on headphones the stereo image is moved from
       inside your head (standard for headphones) to outside and in front of
       the listener (standard for speakers).

       Ported from SoX.

   equalizer
       Apply a two-pole peaking equalisation (EQ) filter. With this filter,
       the signal-level at and around a selected frequency can be increased or
       decreased, whilst (unlike bandpass and bandreject filters) that at all
       other frequencies is unchanged.

       In order to produce complex equalisation curves, this filter can be
       given several times, each with a different central frequency.

       The filter accepts the following options:

       frequency, f
	   Set the filter's central frequency in Hz.

       width_type, t
	   Set method to specify band-width of filter.

	   h   Hz

	   q   Q-Factor

	   o   octave

	   s   slope

	   k   kHz

       width, w
	   Specify the band-width of a filter in width_type units.

       gain, g
	   Set the required gain or attenuation in dB.	Beware of clipping
	   when using a positive gain.

       channels, c
	   Specify which channels to filter, by default all available are
	   filtered.

       Examples

       ·   Attenuate 10 dB at 1000 Hz, with a bandwidth of 200 Hz:

		   equalizer=f=1000:t=h:width=200:g=-10

       ·   Apply 2 dB gain at 1000 Hz with Q 1 and attenuate 5 dB at 100 Hz
	   with Q 2:

		   equalizer=f=1000:t=q:w=1:g=2,equalizer=f=100:t=q:w=2:g=-5

       Commands

       This filter supports the following commands:

       frequency, f
	   Change equalizer frequency.	Syntax for the command is :
	   "frequency"

       width_type, t
	   Change equalizer width_type.  Syntax for the command is :
	   "width_type"

       width, w
	   Change equalizer width.  Syntax for the command is : "width"

       gain, g
	   Change equalizer gain.  Syntax for the command is : "gain"

   extrastereo
       Linearly increases the difference between left and right channels which
       adds some sort of "live" effect to playback.

       The filter accepts the following options:

       m   Sets the difference coefficient (default: 2.5). 0.0 means mono
	   sound (average of both channels), with 1.0 sound will be unchanged,
	   with -1.0 left and right channels will be swapped.

       c   Enable clipping. By default is enabled.

   firequalizer
       Apply FIR Equalization using arbitrary frequency response.

       The filter accepts the following option:

       gain
	   Set gain curve equation (in dB). The expression can contain
	   variables:

	   f   the evaluated frequency

	   sr  sample rate

	   ch  channel number, set to 0 when multichannels evaluation is
	       disabled

	   chid
	       channel id, see libavutil/channel_layout.h, set to the first
	       channel id when multichannels evaluation is disabled

	   chs number of channels

	   chlayout
	       channel_layout, see libavutil/channel_layout.h

	   and functions:

	   gain_interpolate(f)
	       interpolate gain on frequency f based on gain_entry

	   cubic_interpolate(f)
	       same as gain_interpolate, but smoother

	   This option is also available as command. Default is
	   gain_interpolate(f).

       gain_entry
	   Set gain entry for gain_interpolate function. The expression can
	   contain functions:

	   entry(f, g)
	       store gain entry at frequency f with value g

	   This option is also available as command.

       delay
	   Set filter delay in seconds. Higher value means more accurate.
	   Default is 0.01.

       accuracy
	   Set filter accuracy in Hz. Lower value means more accurate.
	   Default is 5.

       wfunc
	   Set window function. Acceptable values are:

	   rectangular
	       rectangular window, useful when gain curve is already smooth

	   hann
	       hann window (default)

	   hamming
	       hamming window

	   blackman
	       blackman window

	   nuttall3
	       3-terms continuous 1st derivative nuttall window

	   mnuttall3
	       minimum 3-terms discontinuous nuttall window

	   nuttall
	       4-terms continuous 1st derivative nuttall window

	   bnuttall
	       minimum 4-terms discontinuous nuttall (blackman-nuttall) window

	   bharris
	       blackman-harris window

	   tukey
	       tukey window

       fixed
	   If enabled, use fixed number of audio samples. This improves speed
	   when filtering with large delay. Default is disabled.

       multi
	   Enable multichannels evaluation on gain. Default is disabled.

       zero_phase
	   Enable zero phase mode by subtracting timestamp to compensate
	   delay.  Default is disabled.

       scale
	   Set scale used by gain. Acceptable values are:

	   linlin
	       linear frequency, linear gain

	   linlog
	       linear frequency, logarithmic (in dB) gain (default)

	   loglin
	       logarithmic (in octave scale where 20 Hz is 0) frequency,
	       linear gain

	   loglog
	       logarithmic frequency, logarithmic gain

       dumpfile
	   Set file for dumping, suitable for gnuplot.

       dumpscale
	   Set scale for dumpfile. Acceptable values are same with scale
	   option.  Default is linlog.

       fft2
	   Enable 2-channel convolution using complex FFT. This improves speed
	   significantly.  Default is disabled.

       min_phase
	   Enable minimum phase impulse response. Default is disabled.

       Examples

       ·   lowpass at 1000 Hz:

		   firequalizer=gain='if(lt(f,1000), 0, -INF)'

       ·   lowpass at 1000 Hz with gain_entry:

		   firequalizer=gain_entry='entry(1000,0); entry(1001, -INF)'

       ·   custom equalization:

		   firequalizer=gain_entry='entry(100,0); entry(400, -4); entry(1000, -6); entry(2000, 0)'

       ·   higher delay with zero phase to compensate delay:

		   firequalizer=delay=0.1:fixed=on:zero_phase=on

       ·   lowpass on left channel, highpass on right channel:

		   firequalizer=gain='if(eq(chid,1), gain_interpolate(f), if(eq(chid,2), gain_interpolate(1e6+f), 0))'
		   :gain_entry='entry(1000, 0); entry(1001,-INF); entry(1e6+1000,0)':multi=on

   flanger
       Apply a flanging effect to the audio.

       The filter accepts the following options:

       delay
	   Set base delay in milliseconds. Range from 0 to 30. Default value
	   is 0.

       depth
	   Set added sweep delay in milliseconds. Range from 0 to 10. Default
	   value is 2.

       regen
	   Set percentage regeneration (delayed signal feedback). Range from
	   -95 to 95.  Default value is 0.

       width
	   Set percentage of delayed signal mixed with original. Range from 0
	   to 100.  Default value is 71.

       speed
	   Set sweeps per second (Hz). Range from 0.1 to 10. Default value is
	   0.5.

       shape
	   Set swept wave shape, can be triangular or sinusoidal.  Default
	   value is sinusoidal.

       phase
	   Set swept wave percentage-shift for multi channel. Range from 0 to
	   100.  Default value is 25.

       interp
	   Set delay-line interpolation, linear or quadratic.  Default is
	   linear.

   haas
       Apply Haas effect to audio.

       Note that this makes most sense to apply on mono signals.  With this
       filter applied to mono signals it give some directionality and
       stretches its stereo image.

       The filter accepts the following options:

       level_in
	   Set input level. By default is 1, or 0dB

       level_out
	   Set output level. By default is 1, or 0dB.

       side_gain
	   Set gain applied to side part of signal. By default is 1.

       middle_source
	   Set kind of middle source. Can be one of the following:

	   left
	       Pick left channel.

	   right
	       Pick right channel.

	   mid Pick middle part signal of stereo image.

	   side
	       Pick side part signal of stereo image.

       middle_phase
	   Change middle phase. By default is disabled.

       left_delay
	   Set left channel delay. By default is 2.05 milliseconds.

       left_balance
	   Set left channel balance. By default is -1.

       left_gain
	   Set left channel gain. By default is 1.

       left_phase
	   Change left phase. By default is disabled.

       right_delay
	   Set right channel delay. By defaults is 2.12 milliseconds.

       right_balance
	   Set right channel balance. By default is 1.

       right_gain
	   Set right channel gain. By default is 1.

       right_phase
	   Change right phase. By default is enabled.

   hdcd
       Decodes High Definition Compatible Digital (HDCD) data. A 16-bit PCM
       stream with embedded HDCD codes is expanded into a 20-bit PCM stream.

       The filter supports the Peak Extend and Low-level Gain Adjustment
       features of HDCD, and detects the Transient Filter flag.

	       ffmpeg -i HDCD16.flac -af hdcd OUT24.flac

       When using the filter with wav, note the default encoding for wav is
       16-bit, so the resulting 20-bit stream will be truncated back to
       16-bit. Use something like -acodec pcm_s24le after the filter to get
       24-bit PCM output.

	       ffmpeg -i HDCD16.wav -af hdcd OUT16.wav
	       ffmpeg -i HDCD16.wav -af hdcd -c:a pcm_s24le OUT24.wav

       The filter accepts the following options:

       disable_autoconvert
	   Disable any automatic format conversion or resampling in the filter
	   graph.

       process_stereo
	   Process the stereo channels together. If target_gain does not match
	   between channels, consider it invalid and use the last valid
	   target_gain.

       cdt_ms
	   Set the code detect timer period in ms.

       force_pe
	   Always extend peaks above -3dBFS even if PE isn't signaled.

       analyze_mode
	   Replace audio with a solid tone and adjust the amplitude to signal
	   some specific aspect of the decoding process. The output file can
	   be loaded in an audio editor alongside the original to aid
	   analysis.

	   "analyze_mode=pe:force_pe=true" can be used to see all samples
	   above the PE level.

	   Modes are:

	   0, off
	       Disabled

	   1, lle
	       Gain adjustment level at each sample

	   2, pe
	       Samples where peak extend occurs

	   3, cdt
	       Samples where the code detect timer is active

	   4, tgm
	       Samples where the target gain does not match between channels

   headphone
       Apply head-related transfer functions (HRTFs) to create virtual
       loudspeakers around the user for binaural listening via headphones.
       The HRIRs are provided via additional streams, for each channel one
       stereo input stream is needed.

       The filter accepts the following options:

       map Set mapping of input streams for convolution.  The argument is a
	   '|'-separated list of channel names in order as they are given as
	   additional stream inputs for filter.  This also specify number of
	   input streams. Number of input streams must be not less than number
	   of channels in first stream plus one.

       gain
	   Set gain applied to audio. Value is in dB. Default is 0.

       type
	   Set processing type. Can be time or freq. time is processing audio
	   in time domain which is slow.  freq is processing audio in
	   frequency domain which is fast.  Default is freq.

       lfe Set custom gain for LFE channels. Value is in dB. Default is 0.

       size
	   Set size of frame in number of samples which will be processed at
	   once.  Default value is 1024. Allowed range is from 1024 to 96000.

       hrir
	   Set format of hrir stream.  Default value is stereo. Alternative
	   value is multich.  If value is set to stereo, number of additional
	   streams should be greater or equal to number of input channels in
	   first input stream.	Also each additional stream should have stereo
	   number of channels.	If value is set to multich, number of
	   additional streams should be exactly one. Also number of input
	   channels of additional stream should be equal or greater than twice
	   number of channels of first input stream.

       Examples

       ·   Full example using wav files as coefficients with amovie filters
	   for 7.1 downmix, each amovie filter use stereo file with IR
	   coefficients as input.  The files give coefficients for each
	   position of virtual loudspeaker:

		   ffmpeg -i input.wav -lavfi-complex "amovie=azi_270_ele_0_DFC.wav[sr],amovie=azi_90_ele_0_DFC.wav[sl],amovie=azi_225_ele_0_DFC.wav[br],amovie=azi_135_ele_0_DFC.wav[bl],amovie=azi_0_ele_0_DFC.wav,asplit[fc][lfe],amovie=azi_35_ele_0_DFC.wav[fl],amovie=azi_325_ele_0_DFC.wav[fr],[a:0][fl][fr][fc][lfe][bl][br][sl][sr]headphone=FL|FR|FC|LFE|BL|BR|SL|SR"
		   output.wav

       ·   Full example using wav files as coefficients with amovie filters
	   for 7.1 downmix, but now in multich hrir format.

		   ffmpeg -i input.wav -lavfi-complex "amovie=minp.wav[hrirs],[a:0][hrirs]headphone=map=FL|FR|FC|LFE|BL|BR|SL|SR:hrir=multich"
		   output.wav

   highpass
       Apply a high-pass filter with 3dB point frequency.  The filter can be
       either single-pole, or double-pole (the default).  The filter roll off
       at 6dB per pole per octave (20dB per pole per decade).

       The filter accepts the following options:

       frequency, f
	   Set frequency in Hz. Default is 3000.

       poles, p
	   Set number of poles. Default is 2.

       width_type, t
	   Set method to specify band-width of filter.

	   h   Hz

	   q   Q-Factor

	   o   octave

	   s   slope

	   k   kHz

       width, w
	   Specify the band-width of a filter in width_type units.  Applies
	   only to double-pole filter.	The default is 0.707q and gives a
	   Butterworth response.

       channels, c
	   Specify which channels to filter, by default all available are
	   filtered.

       Commands

       This filter supports the following commands:

       frequency, f
	   Change highpass frequency.  Syntax for the command is : "frequency"

       width_type, t
	   Change highpass width_type.	Syntax for the command is :
	   "width_type"

       width, w
	   Change highpass width.  Syntax for the command is : "width"

   join
       Join multiple input streams into one multi-channel stream.

       It accepts the following parameters:

       inputs
	   The number of input streams. It defaults to 2.

       channel_layout
	   The desired output channel layout. It defaults to stereo.

       map Map channels from inputs to output. The argument is a '|'-separated
	   list of mappings, each in the "input_idx.in_channel-out_channel"
	   form. input_idx is the 0-based index of the input stream.
	   in_channel can be either the name of the input channel (e.g. FL for
	   front left) or its index in the specified input stream. out_channel
	   is the name of the output channel.

       The filter will attempt to guess the mappings when they are not
       specified explicitly. It does so by first trying to find an unused
       matching input channel and if that fails it picks the first unused
       input channel.

       Join 3 inputs (with properly set channel layouts):

	       ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT

       Build a 5.1 output from 6 single-channel streams:

	       ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
	       'join=inputs=6:channel_layout=5.1:map=0.0-FL|1.0-FR|2.0-FC|3.0-SL|4.0-SR|5.0-LFE'
	       out

   ladspa
       Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-ladspa".

       file, f
	   Specifies the name of LADSPA plugin library to load. If the
	   environment variable LADSPA_PATH is defined, the LADSPA plugin is
	   searched in each one of the directories specified by the colon
	   separated list in LADSPA_PATH, otherwise in the standard LADSPA
	   paths, which are in this order: HOME/.ladspa/lib/,
	   /usr/local/lib/ladspa/, /usr/lib/ladspa/.

       plugin, p
	   Specifies the plugin within the library. Some libraries contain
	   only one plugin, but others contain many of them. If this is not
	   set filter will list all available plugins within the specified
	   library.

       controls, c
	   Set the '|' separated list of controls which are zero or more
	   floating point values that determine the behavior of the loaded
	   plugin (for example delay, threshold or gain).  Controls need to be
	   defined using the following syntax:
	   c0=value0|c1=value1|c2=value2|..., where valuei is the value set on
	   the i-th control.  Alternatively they can be also defined using the
	   following syntax: value0|value1|value2|..., where valuei is the
	   value set on the i-th control.  If controls is set to "help", all
	   available controls and their valid ranges are printed.

       sample_rate, s
	   Specify the sample rate, default to 44100. Only used if plugin have
	   zero inputs.

       nb_samples, n
	   Set the number of samples per channel per each output frame,
	   default is 1024. Only used if plugin have zero inputs.

       duration, d
	   Set the minimum duration of the sourced audio. See the Time
	   duration section in the ffmpeg-utils(1) manual for the accepted
	   syntax.  Note that the resulting duration may be greater than the
	   specified duration, as the generated audio is always cut at the end
	   of a complete frame.  If not specified, or the expressed duration
	   is negative, the audio is supposed to be generated forever.	Only
	   used if plugin have zero inputs.

       Examples

       ·   List all available plugins within amp (LADSPA example plugin)
	   library:

		   ladspa=file=amp

       ·   List all available controls and their valid ranges for "vcf_notch"
	   plugin from "VCF" library:

		   ladspa=f=vcf:p=vcf_notch:c=help

       ·   Simulate low quality audio equipment using "Computer Music Toolkit"
	   (CMT) plugin library:

		   ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12

       ·   Add reverberation to the audio using TAP-plugins (Tom's Audio
	   Processing plugins):

		   ladspa=file=tap_reverb:tap_reverb

       ·   Generate white noise, with 0.2 amplitude:

		   ladspa=file=cmt:noise_source_white:c=c0=.2

       ·   Generate 20 bpm clicks using plugin "C* Click - Metronome" from the
	   "C* Audio Plugin Suite" (CAPS) library:

		   ladspa=file=caps:Click:c=c1=20'

       ·   Apply "C* Eq10X2 - Stereo 10-band equaliser" effect:

		   ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2

       ·   Increase volume by 20dB using fast lookahead limiter from Steve
	   Harris "SWH Plugins" collection:

		   ladspa=fast_lookahead_limiter_1913:fastLookaheadLimiter:20|0|2

       ·   Attenuate low frequencies using Multiband EQ from Steve Harris "SWH
	   Plugins" collection:

		   ladspa=mbeq_1197:mbeq:-24|-24|-24|0|0|0|0|0|0|0|0|0|0|0|0

       ·   Reduce stereo image using "Narrower" from the "C* Audio Plugin
	   Suite" (CAPS) library:

		   ladspa=caps:Narrower

       ·   Another white noise, now using "C* Audio Plugin Suite" (CAPS)
	   library:

		   ladspa=caps:White:.2

       ·   Some fractal noise, using "C* Audio Plugin Suite" (CAPS) library:

		   ladspa=caps:Fractal:c=c1=1

       ·   Dynamic volume normalization using "VLevel" plugin:

		   ladspa=vlevel-ladspa:vlevel_mono

       Commands

       This filter supports the following commands:

       cN  Modify the N-th control value.

	   If the specified value is not valid, it is ignored and prior one is
	   kept.

   loudnorm
       EBU R128 loudness normalization. Includes both dynamic and linear
       normalization modes.  Support for both single pass (livestreams, files)
       and double pass (files) modes.  This algorithm can target IL, LRA, and
       maximum true peak. To accurately detect true peaks, the audio stream
       will be upsampled to 192 kHz unless the normalization mode is linear.
       Use the "-ar" option or "aresample" filter to explicitly set an output
       sample rate.

       The filter accepts the following options:

       I, i
	   Set integrated loudness target.  Range is -70.0 - -5.0. Default
	   value is -24.0.

       LRA, lra
	   Set loudness range target.  Range is 1.0 - 20.0. Default value is
	   7.0.

       TP, tp
	   Set maximum true peak.  Range is -9.0 - +0.0. Default value is
	   -2.0.

       measured_I, measured_i
	   Measured IL of input file.  Range is -99.0 - +0.0.

       measured_LRA, measured_lra
	   Measured LRA of input file.	Range is  0.0 - 99.0.

       measured_TP, measured_tp
	   Measured true peak of input file.  Range is	-99.0 - +99.0.

       measured_thresh
	   Measured threshold of input file.  Range is -99.0 - +0.0.

       offset
	   Set offset gain. Gain is applied before the true-peak limiter.
	   Range is  -99.0 - +99.0. Default is +0.0.

       linear
	   Normalize linearly if possible.  measured_I, measured_LRA,
	   measured_TP, and measured_thresh must also to be specified in order
	   to use this mode.  Options are true or false. Default is true.

       dual_mono
	   Treat mono input files as "dual-mono". If a mono file is intended
	   for playback on a stereo system, its EBU R128 measurement will be
	   perceptually incorrect.  If set to "true", this option will
	   compensate for this effect.	Multi-channel input files are not
	   affected by this option.  Options are true or false. Default is
	   false.

       print_format
	   Set print format for stats. Options are summary, json, or none.
	   Default value is none.

   lowpass
       Apply a low-pass filter with 3dB point frequency.  The filter can be
       either single-pole or double-pole (the default).  The filter roll off
       at 6dB per pole per octave (20dB per pole per decade).

       The filter accepts the following options:

       frequency, f
	   Set frequency in Hz. Default is 500.

       poles, p
	   Set number of poles. Default is 2.

       width_type, t
	   Set method to specify band-width of filter.

	   h   Hz

	   q   Q-Factor

	   o   octave

	   s   slope

	   k   kHz

       width, w
	   Specify the band-width of a filter in width_type units.  Applies
	   only to double-pole filter.	The default is 0.707q and gives a
	   Butterworth response.

       channels, c
	   Specify which channels to filter, by default all available are
	   filtered.

       Examples

       ·   Lowpass only LFE channel, it LFE is not present it does nothing:

		   lowpass=c=LFE

       Commands

       This filter supports the following commands:

       frequency, f
	   Change lowpass frequency.  Syntax for the command is : "frequency"

       width_type, t
	   Change lowpass width_type.  Syntax for the command is :
	   "width_type"

       width, w
	   Change lowpass width.  Syntax for the command is : "width"

   lv2
       Load a LV2 (LADSPA Version 2) plugin.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-lv2".

       plugin, p
	   Specifies the plugin URI. You may need to escape ':'.

       controls, c
	   Set the '|' separated list of controls which are zero or more
	   floating point values that determine the behavior of the loaded
	   plugin (for example delay, threshold or gain).  If controls is set
	   to "help", all available controls and their valid ranges are
	   printed.

       sample_rate, s
	   Specify the sample rate, default to 44100. Only used if plugin have
	   zero inputs.

       nb_samples, n
	   Set the number of samples per channel per each output frame,
	   default is 1024. Only used if plugin have zero inputs.

       duration, d
	   Set the minimum duration of the sourced audio. See the Time
	   duration section in the ffmpeg-utils(1) manual for the accepted
	   syntax.  Note that the resulting duration may be greater than the
	   specified duration, as the generated audio is always cut at the end
	   of a complete frame.  If not specified, or the expressed duration
	   is negative, the audio is supposed to be generated forever.	Only
	   used if plugin have zero inputs.

       Examples

       ·   Apply bass enhancer plugin from Calf:

		   lv2=p=http\\\\://calf.sourceforge.net/plugins/BassEnhancer:c=amount=2

       ·   Apply vinyl plugin from Calf:

		   lv2=p=http\\\\://calf.sourceforge.net/plugins/Vinyl:c=drone=0.2|aging=0.5

       ·   Apply bit crusher plugin from ArtyFX:

		   lv2=p=http\\\\://www.openavproductions.com/artyfx#bitta:c=crush=0.3

   mcompand
       Multiband Compress or expand the audio's dynamic range.

       The input audio is divided into bands using 4th order Linkwitz-Riley
       IIRs.  This is akin to the crossover of a loudspeaker, and results in
       flat frequency response when absent compander action.

       It accepts the following parameters:

       args
	   This option syntax is: attack,decay,[attack,decay..] soft-knee
	   points crossover_frequency [delay [initial_volume [gain]]] |
	   attack,decay ...  For explanation of each item refer to compand
	   filter documentation.

   pan
       Mix channels with specific gain levels. The filter accepts the output
       channel layout followed by a set of channels definitions.

       This filter is also designed to efficiently remap the channels of an
       audio stream.

       The filter accepts parameters of the form: "l|outdef|outdef|..."

       l   output channel layout or number of channels

       outdef
	   output channel specification, of the form:
	   "out_name=[gain*]in_name[(+-)[gain*]in_name...]"

       out_name
	   output channel to define, either a channel name (FL, FR, etc.) or a
	   channel number (c0, c1, etc.)

       gain
	   multiplicative coefficient for the channel, 1 leaving the volume
	   unchanged

       in_name
	   input channel to use, see out_name for details; it is not possible
	   to mix named and numbered input channels

       If the `=' in a channel specification is replaced by `<', then the
       gains for that specification will be renormalized so that the total is
       1, thus avoiding clipping noise.

       Mixing examples

       For example, if you want to down-mix from stereo to mono, but with a
       bigger factor for the left channel:

	       pan=1c|c0=0.9*c0+0.1*c1

       A customized down-mix to stereo that works automatically for 3-, 4-, 5-
       and 7-channels surround:

	       pan=stereo| FL < FL + 0.5*FC + 0.6*BL + 0.6*SL | FR < FR + 0.5*FC + 0.6*BR + 0.6*SR

       Note that ffmpeg integrates a default down-mix (and up-mix) system that
       should be preferred (see "-ac" option) unless you have very specific
       needs.

       Remapping examples

       The channel remapping will be effective if, and only if:

       *<gain coefficients are zeroes or ones,>
       *<only one input per channel output,>

       If all these conditions are satisfied, the filter will notify the user
       ("Pure channel mapping detected"), and use an optimized and lossless
       method to do the remapping.

       For example, if you have a 5.1 source and want a stereo audio stream by
       dropping the extra channels:

	       pan="stereo| c0=FL | c1=FR"

       Given the same source, you can also switch front left and front right
       channels and keep the input channel layout:

	       pan="5.1| c0=c1 | c1=c0 | c2=c2 | c3=c3 | c4=c4 | c5=c5"

       If the input is a stereo audio stream, you can mute the front left
       channel (and still keep the stereo channel layout) with:

	       pan="stereo|c1=c1"

       Still with a stereo audio stream input, you can copy the right channel
       in both front left and right:

	       pan="stereo| c0=FR | c1=FR"

   replaygain
       ReplayGain scanner filter. This filter takes an audio stream as an
       input and outputs it unchanged.	At end of filtering it displays
       "track_gain" and "track_peak".

   resample
       Convert the audio sample format, sample rate and channel layout. It is
       not meant to be used directly.

   rubberband
       Apply time-stretching and pitch-shifting with librubberband.

       To enable compilation of this filter, you need to configure FFmpeg with
       "--enable-librubberband".

       The filter accepts the following options:

       tempo
	   Set tempo scale factor.

       pitch
	   Set pitch scale factor.

       transients
	   Set transients detector.  Possible values are:

	   crisp
	   mixed
	   smooth
       detector
	   Set detector.  Possible values are:

	   compound
	   percussive
	   soft
       phase
	   Set phase.  Possible values are:

	   laminar
	   independent
       window
	   Set processing window size.	Possible values are:

	   standard
	   short
	   long
       smoothing
	   Set smoothing.  Possible values are:

	   off
	   on
       formant
	   Enable formant preservation when shift pitching.  Possible values
	   are:

	   shifted
	   preserved
       pitchq
	   Set pitch quality.  Possible values are:

	   quality
	   speed
	   consistency
       channels
	   Set channels.  Possible values are:

	   apart
	   together

   sidechaincompress
       This filter acts like normal compressor but has the ability to compress
       detected signal using second input signal.  It needs two input streams
       and returns one output stream.  First input stream will be processed
       depending on second stream signal.  The filtered signal then can be
       filtered with other filters in later stages of processing. See pan and
       amerge filter.

       The filter accepts the following options:

       level_in
	   Set input gain. Default is 1. Range is between 0.015625 and 64.

       threshold
	   If a signal of second stream raises above this level it will affect
	   the gain reduction of first stream.	By default is 0.125. Range is
	   between 0.00097563 and 1.

       ratio
	   Set a ratio about which the signal is reduced. 1:2 means that if
	   the level raised 4dB above the threshold, it will be only 2dB above
	   after the reduction.  Default is 2. Range is between 1 and 20.

       attack
	   Amount of milliseconds the signal has to rise above the threshold
	   before gain reduction starts. Default is 20. Range is between 0.01
	   and 2000.

       release
	   Amount of milliseconds the signal has to fall below the threshold
	   before reduction is decreased again. Default is 250. Range is
	   between 0.01 and 9000.

       makeup
	   Set the amount by how much signal will be amplified after
	   processing.	Default is 1. Range is from 1 to 64.

       knee
	   Curve the sharp knee around the threshold to enter gain reduction
	   more softly.  Default is 2.82843. Range is between 1 and 8.

       link
	   Choose if the "average" level between all channels of side-chain
	   stream or the louder("maximum") channel of side-chain stream
	   affects the reduction. Default is "average".

       detection
	   Should the exact signal be taken in case of "peak" or an RMS one in
	   case of "rms". Default is "rms" which is mainly smoother.

       level_sc
	   Set sidechain gain. Default is 1. Range is between 0.015625 and 64.

       mix How much to use compressed signal in output. Default is 1.  Range
	   is between 0 and 1.

       Examples

       ·   Full ffmpeg example taking 2 audio inputs, 1st input to be
	   compressed depending on the signal of 2nd input and later
	   compressed signal to be merged with 2nd input:

		   ffmpeg -i main.flac -i sidechain.flac -filter_complex "[1:a]asplit=2[sc][mix];[0:a][sc]sidechaincompress[compr];[compr][mix]amerge"

   sidechaingate
       A sidechain gate acts like a normal (wideband) gate but has the ability
       to filter the detected signal before sending it to the gain reduction
       stage.  Normally a gate uses the full range signal to detect a level
       above the threshold.  For example: If you cut all lower frequencies
       from your sidechain signal the gate will decrease the volume of your
       track only if not enough highs appear. With this technique you are able
       to reduce the resonation of a natural drum or remove "rumbling" of
       muted strokes from a heavily distorted guitar.  It needs two input
       streams and returns one output stream.  First input stream will be
       processed depending on second stream signal.

       The filter accepts the following options:

       level_in
	   Set input level before filtering.  Default is 1. Allowed range is
	   from 0.015625 to 64.

       range
	   Set the level of gain reduction when the signal is below the
	   threshold.  Default is 0.06125. Allowed range is from 0 to 1.

       threshold
	   If a signal rises above this level the gain reduction is released.
	   Default is 0.125. Allowed range is from 0 to 1.

       ratio
	   Set a ratio about which the signal is reduced.  Default is 2.
	   Allowed range is from 1 to 9000.

       attack
	   Amount of milliseconds the signal has to rise above the threshold
	   before gain reduction stops.  Default is 20 milliseconds. Allowed
	   range is from 0.01 to 9000.

       release
	   Amount of milliseconds the signal has to fall below the threshold
	   before the reduction is increased again. Default is 250
	   milliseconds.  Allowed range is from 0.01 to 9000.

       makeup
	   Set amount of amplification of signal after processing.  Default is
	   1. Allowed range is from 1 to 64.

       knee
	   Curve the sharp knee around the threshold to enter gain reduction
	   more softly.  Default is 2.828427125. Allowed range is from 1 to 8.

       detection
	   Choose if exact signal should be taken for detection or an RMS like
	   one.  Default is rms. Can be peak or rms.

       link
	   Choose if the average level between all channels or the louder
	   channel affects the reduction.  Default is average. Can be average
	   or maximum.

       level_sc
	   Set sidechain gain. Default is 1. Range is from 0.015625 to 64.

   silencedetect
       Detect silence in an audio stream.

       This filter logs a message when it detects that the input audio volume
       is less or equal to a noise tolerance value for a duration greater or
       equal to the minimum detected noise duration.

       The printed times and duration are expressed in seconds.

       The filter accepts the following options:

       duration, d
	   Set silence duration until notification (default is 2 seconds).

       noise, n
	   Set noise tolerance. Can be specified in dB (in case "dB" is
	   appended to the specified value) or amplitude ratio. Default is
	   -60dB, or 0.001.

       Examples

       ·   Detect 5 seconds of silence with -50dB noise tolerance:

		   silencedetect=n=-50dB:d=5

       ·   Complete example with ffmpeg to detect silence with 0.0001 noise
	   tolerance in silence.mp3:

		   ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -

   silenceremove
       Remove silence from the beginning, middle or end of the audio.

       The filter accepts the following options:

       start_periods
	   This value is used to indicate if audio should be trimmed at
	   beginning of the audio. A value of zero indicates no silence should
	   be trimmed from the beginning. When specifying a non-zero value, it
	   trims audio up until it finds non-silence. Normally, when trimming
	   silence from beginning of audio the start_periods will be 1 but it
	   can be increased to higher values to trim all audio up to specific
	   count of non-silence periods.  Default value is 0.

       start_duration
	   Specify the amount of time that non-silence must be detected before
	   it stops trimming audio. By increasing the duration, bursts of
	   noises can be treated as silence and trimmed off. Default value is
	   0.

       start_threshold
	   This indicates what sample value should be treated as silence. For
	   digital audio, a value of 0 may be fine but for audio recorded from
	   analog, you may wish to increase the value to account for
	   background noise.  Can be specified in dB (in case "dB" is appended
	   to the specified value) or amplitude ratio. Default value is 0.

       stop_periods
	   Set the count for trimming silence from the end of audio.  To
	   remove silence from the middle of a file, specify a stop_periods
	   that is negative. This value is then treated as a positive value
	   and is used to indicate the effect should restart processing as
	   specified by start_periods, making it suitable for removing periods
	   of silence in the middle of the audio.  Default value is 0.

       stop_duration
	   Specify a duration of silence that must exist before audio is not
	   copied any more. By specifying a higher duration, silence that is
	   wanted can be left in the audio.  Default value is 0.

       stop_threshold
	   This is the same as start_threshold but for trimming silence from
	   the end of audio.  Can be specified in dB (in case "dB" is appended
	   to the specified value) or amplitude ratio. Default value is 0.

       leave_silence
	   This indicates that stop_duration length of audio should be left
	   intact at the beginning of each period of silence.  For example, if
	   you want to remove long pauses between words but do not want to
	   remove the pauses completely. Default value is 0.

       detection
	   Set how is silence detected. Can be "rms" or "peak". Second is
	   faster and works better with digital silence which is exactly 0.
	   Default value is "rms".

       window
	   Set ratio used to calculate size of window for detecting silence.
	   Default value is 0.02. Allowed range is from 0 to 10.

       Examples

       ·   The following example shows how this filter can be used to start a
	   recording that does not contain the delay at the start which
	   usually occurs between pressing the record button and the start of
	   the performance:

		   silenceremove=1:5:0.02

       ·   Trim all silence encountered from beginning to end where there is
	   more than 1 second of silence in audio:

		   silenceremove=0:0:0:-1:1:-90dB

   sofalizer
       SOFAlizer uses head-related transfer functions (HRTFs) to create
       virtual loudspeakers around the user for binaural listening via
       headphones (audio formats up to 9 channels supported).  The HRTFs are
       stored in SOFA files (see <http://www.sofacoustics.org/> for a
       database).  SOFAlizer is developed at the Acoustics Research Institute
       (ARI) of the Austrian Academy of Sciences.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-libmysofa".

       The filter accepts the following options:

       sofa
	   Set the SOFA file used for rendering.

       gain
	   Set gain applied to audio. Value is in dB. Default is 0.

       rotation
	   Set rotation of virtual loudspeakers in deg. Default is 0.

       elevation
	   Set elevation of virtual speakers in deg. Default is 0.

       radius
	   Set distance in meters between loudspeakers and the listener with
	   near-field HRTFs. Default is 1.

       type
	   Set processing type. Can be time or freq. time is processing audio
	   in time domain which is slow.  freq is processing audio in
	   frequency domain which is fast.  Default is freq.

       speakers
	   Set custom positions of virtual loudspeakers. Syntax for this
	   option is: <CH> <AZIM> <ELEV>[|<CH> <AZIM> <ELEV>|...].  Each
	   virtual loudspeaker is described with short channel name following
	   with azimuth and elevation in degrees.  Each virtual loudspeaker
	   description is separated by '|'.  For example to override front
	   left and front right channel positions use: 'speakers=FL 45 15|FR
	   345 15'.  Descriptions with unrecognised channel names are ignored.

       lfegain
	   Set custom gain for LFE channels. Value is in dB. Default is 0.

       Examples

       ·   Using ClubFritz6 sofa file:

		   sofalizer=sofa=/path/to/ClubFritz6.sofa:type=freq:radius=1

       ·   Using ClubFritz12 sofa file and bigger radius with small rotation:

		   sofalizer=sofa=/path/to/ClubFritz12.sofa:type=freq:radius=2:rotation=5

       ·   Similar as above but with custom speaker positions for front left,
	   front right, back left and back right and also with custom gain:

		   "sofalizer=sofa=/path/to/ClubFritz6.sofa:type=freq:radius=2:speakers=FL 45|FR 315|BL 135|BR 225:gain=28"

   stereotools
       This filter has some handy utilities to manage stereo signals, for
       converting M/S stereo recordings to L/R signal while having control
       over the parameters or spreading the stereo image of master track.

       The filter accepts the following options:

       level_in
	   Set input level before filtering for both channels. Defaults is 1.
	   Allowed range is from 0.015625 to 64.

       level_out
	   Set output level after filtering for both channels. Defaults is 1.
	   Allowed range is from 0.015625 to 64.

       balance_in
	   Set input balance between both channels. Default is 0.  Allowed
	   range is from -1 to 1.

       balance_out
	   Set output balance between both channels. Default is 0.  Allowed
	   range is from -1 to 1.

       softclip
	   Enable softclipping. Results in analog distortion instead of harsh
	   digital 0dB clipping. Disabled by default.

       mutel
	   Mute the left channel. Disabled by default.

       muter
	   Mute the right channel. Disabled by default.

       phasel
	   Change the phase of the left channel. Disabled by default.

       phaser
	   Change the phase of the right channel. Disabled by default.

       mode
	   Set stereo mode. Available values are:

	   lr>lr
	       Left/Right to Left/Right, this is default.

	   lr>ms
	       Left/Right to Mid/Side.

	   ms>lr
	       Mid/Side to Left/Right.

	   lr>ll
	       Left/Right to Left/Left.

	   lr>rr
	       Left/Right to Right/Right.

	   lr>l+r
	       Left/Right to Left + Right.

	   lr>rl
	       Left/Right to Right/Left.

	   ms>ll
	       Mid/Side to Left/Left.

	   ms>rr
	       Mid/Side to Right/Right.

       slev
	   Set level of side signal. Default is 1.  Allowed range is from
	   0.015625 to 64.

       sbal
	   Set balance of side signal. Default is 0.  Allowed range is from -1
	   to 1.

       mlev
	   Set level of the middle signal. Default is 1.  Allowed range is
	   from 0.015625 to 64.

       mpan
	   Set middle signal pan. Default is 0. Allowed range is from -1 to 1.

       base
	   Set stereo base between mono and inversed channels. Default is 0.
	   Allowed range is from -1 to 1.

       delay
	   Set delay in milliseconds how much to delay left from right channel
	   and vice versa. Default is 0. Allowed range is from -20 to 20.

       sclevel
	   Set S/C level. Default is 1. Allowed range is from 1 to 100.

       phase
	   Set the stereo phase in degrees. Default is 0. Allowed range is
	   from 0 to 360.

       bmode_in, bmode_out
	   Set balance mode for balance_in/balance_out option.

	   Can be one of the following:

	   balance
	       Classic balance mode. Attenuate one channel at time.  Gain is
	       raised up to 1.

	   amplitude
	       Similar as classic mode above but gain is raised up to 2.

	   power
	       Equal power distribution, from -6dB to +6dB range.

       Examples

       ·   Apply karaoke like effect:

		   stereotools=mlev=0.015625

       ·   Convert M/S signal to L/R:

		   "stereotools=mode=ms>lr"

   stereowiden
       This filter enhance the stereo effect by suppressing signal common to
       both channels and by delaying the signal of left into right and vice
       versa, thereby widening the stereo effect.

       The filter accepts the following options:

       delay
	   Time in milliseconds of the delay of left signal into right and
	   vice versa.	Default is 20 milliseconds.

       feedback
	   Amount of gain in delayed signal into right and vice versa. Gives a
	   delay effect of left signal in right output and vice versa which
	   gives widening effect. Default is 0.3.

       crossfeed
	   Cross feed of left into right with inverted phase. This helps in
	   suppressing the mono. If the value is 1 it will cancel all the
	   signal common to both channels. Default is 0.3.

       drymix
	   Set level of input signal of original channel. Default is 0.8.

   superequalizer
       Apply 18 band equalizer.

       The filter accepts the following options:

       1b  Set 65Hz band gain.

       2b  Set 92Hz band gain.

       3b  Set 131Hz band gain.

       4b  Set 185Hz band gain.

       5b  Set 262Hz band gain.

       6b  Set 370Hz band gain.

       7b  Set 523Hz band gain.

       8b  Set 740Hz band gain.

       9b  Set 1047Hz band gain.

       10b Set 1480Hz band gain.

       11b Set 2093Hz band gain.

       12b Set 2960Hz band gain.

       13b Set 4186Hz band gain.

       14b Set 5920Hz band gain.

       15b Set 8372Hz band gain.

       16b Set 11840Hz band gain.

       17b Set 16744Hz band gain.

       18b Set 20000Hz band gain.

   surround
       Apply audio surround upmix filter.

       This filter allows to produce multichannel output from audio stream.

       The filter accepts the following options:

       chl_out
	   Set output channel layout. By default, this is 5.1.

	   See the Channel Layout section in the ffmpeg-utils(1) manual for
	   the required syntax.

       chl_in
	   Set input channel layout. By default, this is stereo.

	   See the Channel Layout section in the ffmpeg-utils(1) manual for
	   the required syntax.

       level_in
	   Set input volume level. By default, this is 1.

       level_out
	   Set output volume level. By default, this is 1.

       lfe Enable LFE channel output if output channel layout has it. By
	   default, this is enabled.

       lfe_low
	   Set LFE low cut off frequency. By default, this is 128 Hz.

       lfe_high
	   Set LFE high cut off frequency. By default, this is 256 Hz.

       fc_in
	   Set front center input volume. By default, this is 1.

       fc_out
	   Set front center output volume. By default, this is 1.

       lfe_in
	   Set LFE input volume. By default, this is 1.

       lfe_out
	   Set LFE output volume. By default, this is 1.

   treble, highshelf
       Boost or cut treble (upper) frequencies of the audio using a two-pole
       shelving filter with a response similar to that of a standard hi-fi's
       tone-controls. This is also known as shelving equalisation (EQ).

       The filter accepts the following options:

       gain, g
	   Give the gain at whichever is the lower of ~22 kHz and the Nyquist
	   frequency. Its useful range is about -20 (for a large cut) to +20
	   (for a large boost). Beware of clipping when using a positive gain.

       frequency, f
	   Set the filter's central frequency and so can be used to extend or
	   reduce the frequency range to be boosted or cut.  The default value
	   is 3000 Hz.

       width_type, t
	   Set method to specify band-width of filter.

	   h   Hz

	   q   Q-Factor

	   o   octave

	   s   slope

	   k   kHz

       width, w
	   Determine how steep is the filter's shelf transition.

       channels, c
	   Specify which channels to filter, by default all available are
	   filtered.

       Commands

       This filter supports the following commands:

       frequency, f
	   Change treble frequency.  Syntax for the command is : "frequency"

       width_type, t
	   Change treble width_type.  Syntax for the command is : "width_type"

       width, w
	   Change treble width.  Syntax for the command is : "width"

       gain, g
	   Change treble gain.	Syntax for the command is : "gain"

   tremolo
       Sinusoidal amplitude modulation.

       The filter accepts the following options:

       f   Modulation frequency in Hertz. Modulation frequencies in the
	   subharmonic range (20 Hz or lower) will result in a tremolo effect.
	   This filter may also be used as a ring modulator by specifying a
	   modulation frequency higher than 20 Hz.  Range is 0.1 - 20000.0.
	   Default value is 5.0 Hz.

       d   Depth of modulation as a percentage. Range is 0.0 - 1.0.  Default
	   value is 0.5.

   vibrato
       Sinusoidal phase modulation.

       The filter accepts the following options:

       f   Modulation frequency in Hertz.  Range is 0.1 - 20000.0. Default
	   value is 5.0 Hz.

       d   Depth of modulation as a percentage. Range is 0.0 - 1.0.  Default
	   value is 0.5.

   volume
       Adjust the input audio volume.

       It accepts the following parameters:

       volume
	   Set audio volume expression.

	   Output values are clipped to the maximum value.

	   The output audio volume is given by the relation:

		   <output_volume> = <volume> * <input_volume>

	   The default value for volume is "1.0".

       precision
	   This parameter represents the mathematical precision.

	   It determines which input sample formats will be allowed, which
	   affects the precision of the volume scaling.

	   fixed
	       8-bit fixed-point; this limits input sample format to U8, S16,
	       and S32.

	   float
	       32-bit floating-point; this limits input sample format to FLT.
	       (default)

	   double
	       64-bit floating-point; this limits input sample format to DBL.

       replaygain
	   Choose the behaviour on encountering ReplayGain side data in input
	   frames.

	   drop
	       Remove ReplayGain side data, ignoring its contents (the
	       default).

	   ignore
	       Ignore ReplayGain side data, but leave it in the frame.

	   track
	       Prefer the track gain, if present.

	   album
	       Prefer the album gain, if present.

       replaygain_preamp
	   Pre-amplification gain in dB to apply to the selected replaygain
	   gain.

	   Default value for replaygain_preamp is 0.0.

       eval
	   Set when the volume expression is evaluated.

	   It accepts the following values:

	   once
	       only evaluate expression once during the filter initialization,
	       or when the volume command is sent

	   frame
	       evaluate expression for each incoming frame

	   Default value is once.

       The volume expression can contain the following parameters.

       n   frame number (starting at zero)

       nb_channels
	   number of channels

       nb_consumed_samples
	   number of samples consumed by the filter

       nb_samples
	   number of samples in the current frame

       pos original frame position in the file

       pts frame PTS

       sample_rate
	   sample rate

       startpts
	   PTS at start of stream

       startt
	   time at start of stream

       t   frame time

       tb  timestamp timebase

       volume
	   last set volume value

       Note that when eval is set to once only the sample_rate and tb
       variables are available, all other variables will evaluate to NAN.

       Commands

       This filter supports the following commands:

       volume
	   Modify the volume expression.  The command accepts the same syntax
	   of the corresponding option.

	   If the specified expression is not valid, it is kept at its current
	   value.

       replaygain_noclip
	   Prevent clipping by limiting the gain applied.

	   Default value for replaygain_noclip is 1.

       Examples

       ·   Halve the input audio volume:

		   volume=volume=0.5
		   volume=volume=1/2
		   volume=volume=-6.0206dB

	   In all the above example the named key for volume can be omitted,
	   for example like in:

		   volume=0.5

       ·   Increase input audio power by 6 decibels using fixed-point
	   precision:

		   volume=volume=6dB:precision=fixed

       ·   Fade volume after time 10 with an annihilation period of 5 seconds:

		   volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame

   volumedetect
       Detect the volume of the input video.

       The filter has no parameters. The input is not modified. Statistics
       about the volume will be printed in the log when the input stream end
       is reached.

       In particular it will show the mean volume (root mean square), maximum
       volume (on a per-sample basis), and the beginning of a histogram of the
       registered volume values (from the maximum value to a cumulated 1/1000
       of the samples).

       All volumes are in decibels relative to the maximum PCM value.

       Examples

       Here is an excerpt of the output:

	       [Parsed_volumedetect_0  0xa23120] mean_volume: -27 dB
	       [Parsed_volumedetect_0  0xa23120] max_volume: -4 dB
	       [Parsed_volumedetect_0  0xa23120] histogram_4db: 6
	       [Parsed_volumedetect_0  0xa23120] histogram_5db: 62
	       [Parsed_volumedetect_0  0xa23120] histogram_6db: 286
	       [Parsed_volumedetect_0  0xa23120] histogram_7db: 1042
	       [Parsed_volumedetect_0  0xa23120] histogram_8db: 2551
	       [Parsed_volumedetect_0  0xa23120] histogram_9db: 4609
	       [Parsed_volumedetect_0  0xa23120] histogram_10db: 8409

       It means that:

       ·   The mean square energy is approximately -27 dB, or 10^-2.7.

       ·   The largest sample is at -4 dB, or more precisely between -4 dB and
	   -5 dB.

       ·   There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.

       In other words, raising the volume by +4 dB does not cause any
       clipping, raising it by +5 dB causes clipping for 6 samples, etc.

AUDIO SOURCES
       Below is a description of the currently available audio sources.

   abuffer
       Buffer audio frames, and make them available to the filter chain.

       This source is mainly intended for a programmatic use, in particular
       through the interface defined in libavfilter/asrc_abuffer.h.

       It accepts the following parameters:

       time_base
	   The timebase which will be used for timestamps of submitted frames.
	   It must be either a floating-point number or in
	   numerator/denominator form.

       sample_rate
	   The sample rate of the incoming audio buffers.

       sample_fmt
	   The sample format of the incoming audio buffers.  Either a sample
	   format name or its corresponding integer representation from the
	   enum AVSampleFormat in libavutil/samplefmt.h

       channel_layout
	   The channel layout of the incoming audio buffers.  Either a channel
	   layout name from channel_layout_map in libavutil/channel_layout.c
	   or its corresponding integer representation from the AV_CH_LAYOUT_*
	   macros in libavutil/channel_layout.h

       channels
	   The number of channels of the incoming audio buffers.  If both
	   channels and channel_layout are specified, then they must be
	   consistent.

       Examples

	       abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo

       will instruct the source to accept planar 16bit signed stereo at
       44100Hz.  Since the sample format with name "s16p" corresponds to the
       number 6 and the "stereo" channel layout corresponds to the value 0x3,
       this is equivalent to:

	       abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3

   aevalsrc
       Generate an audio signal specified by an expression.

       This source accepts in input one or more expressions (one for each
       channel), which are evaluated and used to generate a corresponding
       audio signal.

       This source accepts the following options:

       exprs
	   Set the '|'-separated expressions list for each separate channel.
	   In case the channel_layout option is not specified, the selected
	   channel layout depends on the number of provided expressions.
	   Otherwise the last specified expression is applied to the remaining
	   output channels.

       channel_layout, c
	   Set the channel layout. The number of channels in the specified
	   layout must be equal to the number of specified expressions.

       duration, d
	   Set the minimum duration of the sourced audio. See the Time
	   duration section in the ffmpeg-utils(1) manual for the accepted
	   syntax.  Note that the resulting duration may be greater than the
	   specified duration, as the generated audio is always cut at the end
	   of a complete frame.

	   If not specified, or the expressed duration is negative, the audio
	   is supposed to be generated forever.

       nb_samples, n
	   Set the number of samples per channel per each output frame,
	   default to 1024.

       sample_rate, s
	   Specify the sample rate, default to 44100.

       Each expression in exprs can contain the following constants:

       n   number of the evaluated sample, starting from 0

       t   time of the evaluated sample expressed in seconds, starting from 0

       s   sample rate

       Examples

       ·   Generate silence:

		   aevalsrc=0

       ·   Generate a sin signal with frequency of 440 Hz, set sample rate to
	   8000 Hz:

		   aevalsrc="sin(440*2*PI*t):s=8000"

       ·   Generate a two channels signal, specify the channel layout (Front
	   Center + Back Center) explicitly:

		   aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"

       ·   Generate white noise:

		   aevalsrc="-2+random(0)"

       ·   Generate an amplitude modulated signal:

		   aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"

       ·   Generate 2.5 Hz binaural beats on a 360 Hz carrier:

		   aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"

   anullsrc
       The null audio source, return unprocessed audio frames. It is mainly
       useful as a template and to be employed in analysis / debugging tools,
       or as the source for filters which ignore the input data (for example
       the sox synth filter).

       This source accepts the following options:

       channel_layout, cl
	   Specifies the channel layout, and can be either an integer or a
	   string representing a channel layout. The default value of
	   channel_layout is "stereo".

	   Check the channel_layout_map definition in
	   libavutil/channel_layout.c for the mapping between strings and
	   channel layout values.

       sample_rate, r
	   Specifies the sample rate, and defaults to 44100.

       nb_samples, n
	   Set the number of samples per requested frames.

       Examples

       ·   Set the sample rate to 48000 Hz and the channel layout to
	   AV_CH_LAYOUT_MONO.

		   anullsrc=r=48000:cl=4

       ·   Do the same operation with a more obvious syntax:

		   anullsrc=r=48000:cl=mono

       All the parameters need to be explicitly defined.

   flite
       Synthesize a voice utterance using the libflite library.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-libflite".

       Note that versions of the flite library prior to 2.0 are not thread-
       safe.

       The filter accepts the following options:

       list_voices
	   If set to 1, list the names of the available voices and exit
	   immediately. Default value is 0.

       nb_samples, n
	   Set the maximum number of samples per frame. Default value is 512.

       textfile
	   Set the filename containing the text to speak.

       text
	   Set the text to speak.

       voice, v
	   Set the voice to use for the speech synthesis. Default value is
	   "kal". See also the list_voices option.

       Examples

       ·   Read from file speech.txt, and synthesize the text using the
	   standard flite voice:

		   flite=textfile=speech.txt

       ·   Read the specified text selecting the "slt" voice:

		   flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt

       ·   Input text to ffmpeg:

		   ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt

       ·   Make ffplay speak the specified text, using "flite" and the "lavfi"
	   device:

		   ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'

       For more information about libflite, check:
       <http://www.festvox.org/flite/>

   anoisesrc
       Generate a noise audio signal.

       The filter accepts the following options:

       sample_rate, r
	   Specify the sample rate. Default value is 48000 Hz.

       amplitude, a
	   Specify the amplitude (0.0 - 1.0) of the generated audio stream.
	   Default value is 1.0.

       duration, d
	   Specify the duration of the generated audio stream. Not specifying
	   this option results in noise with an infinite length.

       color, colour, c
	   Specify the color of noise. Available noise colors are white, pink,
	   brown, blue and violet. Default color is white.

       seed, s
	   Specify a value used to seed the PRNG.

       nb_samples, n
	   Set the number of samples per each output frame, default is 1024.

       Examples

       ·   Generate 60 seconds of pink noise, with a 44.1 kHz sampling rate
	   and an amplitude of 0.5:

		   anoisesrc=d=60:c=pink:r=44100:a=0.5

   hilbert
       Generate odd-tap Hilbert transform FIR coefficients.

       The resulting stream can be used with afir filter for phase-shifting
       the signal by 90 degrees.

       This is used in many matrix coding schemes and for analytic signal
       generation.  The process is often written as a multiplication by i (or
       j), the imaginary unit.

       The filter accepts the following options:

       sample_rate, s
	   Set sample rate, default is 44100.

       taps, t
	   Set length of FIR filter, default is 22051.

       nb_samples, n
	   Set number of samples per each frame.

       win_func, w
	   Set window function to be used when generating FIR coefficients.

   sine
       Generate an audio signal made of a sine wave with amplitude 1/8.

       The audio signal is bit-exact.

       The filter accepts the following options:

       frequency, f
	   Set the carrier frequency. Default is 440 Hz.

       beep_factor, b
	   Enable a periodic beep every second with frequency beep_factor
	   times the carrier frequency. Default is 0, meaning the beep is
	   disabled.

       sample_rate, r
	   Specify the sample rate, default is 44100.

       duration, d
	   Specify the duration of the generated audio stream.

       samples_per_frame
	   Set the number of samples per output frame.

	   The expression can contain the following constants:

	   n   The (sequential) number of the output audio frame, starting
	       from 0.

	   pts The PTS (Presentation TimeStamp) of the output audio frame,
	       expressed in TB units.

	   t   The PTS of the output audio frame, expressed in seconds.

	   TB  The timebase of the output audio frames.

	   Default is 1024.

       Examples

       ·   Generate a simple 440 Hz sine wave:

		   sine

       ·   Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5
	   seconds:

		   sine=220:4:d=5
		   sine=f=220:b=4:d=5
		   sine=frequency=220:beep_factor=4:duration=5

       ·   Generate a 1 kHz sine wave following "1602,1601,1602,1601,1602"
	   NTSC pattern:

		   sine=1000:samples_per_frame='st(0,mod(n,5)); 1602-not(not(eq(ld(0),1)+eq(ld(0),3)))'

AUDIO SINKS
       Below is a description of the currently available audio sinks.

   abuffersink
       Buffer audio frames, and make them available to the end of filter
       chain.

       This sink is mainly intended for programmatic use, in particular
       through the interface defined in libavfilter/buffersink.h or the
       options system.

       It accepts a pointer to an AVABufferSinkContext structure, which
       defines the incoming buffers' formats, to be passed as the opaque
       parameter to "avfilter_init_filter" for initialization.

   anullsink
       Null audio sink; do absolutely nothing with the input audio. It is
       mainly useful as a template and for use in analysis / debugging tools.

VIDEO FILTERS
       When you configure your FFmpeg build, you can disable any of the
       existing filters using "--disable-filters".  The configure output will
       show the video filters included in your build.

       Below is a description of the currently available video filters.

   alphaextract
       Extract the alpha component from the input as a grayscale video. This
       is especially useful with the alphamerge filter.

   alphamerge
       Add or replace the alpha component of the primary input with the
       grayscale value of a second input. This is intended for use with
       alphaextract to allow the transmission or storage of frame sequences
       that have alpha in a format that doesn't support an alpha channel.

       For example, to reconstruct full frames from a normal YUV-encoded video
       and a separate video created with alphaextract, you might use:

	       movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]

       Since this filter is designed for reconstruction, it operates on frame
       sequences without considering timestamps, and terminates when either
       input reaches end of stream. This will cause problems if your encoding
       pipeline drops frames. If you're trying to apply an image as an overlay
       to a video stream, consider the overlay filter instead.

   amplify
       Amplify differences between current pixel and pixels of adjacent frames
       in same pixel location.

       This filter accepts the following options:

       radius
	   Set frame radius. Default is 2. Allowed range is from 1 to 63.  For
	   example radius of 3 will instruct filter to calculate average of 7
	   frames.

       factor
	   Set factor to amplify difference. Default is 2. Allowed range is
	   from 0 to 65535.

       threshold
	   Set threshold for difference amplification. Any differrence greater
	   or equal to this value will not alter source pixel. Default is 10.
	   Allowed range is from 0 to 65535.

       low Set lower limit for changing source pixel. Default is 65535.
	   Allowed range is from 0 to 65535.  This option controls maximum
	   possible value that will decrease source pixel value.

       high
	   Set high limit for changing source pixel. Default is 65535. Allowed
	   range is from 0 to 65535.  This option controls maximum possible
	   value that will increase source pixel value.

       planes
	   Set which planes to filter. Default is all. Allowed range is from 0
	   to 15.

   ass
       Same as the subtitles filter, except that it doesn't require libavcodec
       and libavformat to work. On the other hand, it is limited to ASS
       (Advanced Substation Alpha) subtitles files.

       This filter accepts the following option in addition to the common
       options from the subtitles filter:

       shaping
	   Set the shaping engine

	   Available values are:

	   auto
	       The default libass shaping engine, which is the best available.

	   simple
	       Fast, font-agnostic shaper that can do only substitutions

	   complex
	       Slower shaper using OpenType for substitutions and positioning

	   The default is "auto".

   atadenoise
       Apply an Adaptive Temporal Averaging Denoiser to the video input.

       The filter accepts the following options:

       0a  Set threshold A for 1st plane. Default is 0.02.  Valid range is 0
	   to 0.3.

       0b  Set threshold B for 1st plane. Default is 0.04.  Valid range is 0
	   to 5.

       1a  Set threshold A for 2nd plane. Default is 0.02.  Valid range is 0
	   to 0.3.

       1b  Set threshold B for 2nd plane. Default is 0.04.  Valid range is 0
	   to 5.

       2a  Set threshold A for 3rd plane. Default is 0.02.  Valid range is 0
	   to 0.3.

       2b  Set threshold B for 3rd plane. Default is 0.04.  Valid range is 0
	   to 5.

	   Threshold A is designed to react on abrupt changes in the input
	   signal and threshold B is designed to react on continuous changes
	   in the input signal.

       s   Set number of frames filter will use for averaging. Default is 9.
	   Must be odd number in range [5, 129].

       p   Set what planes of frame filter will use for averaging. Default is
	   all.

   avgblur
       Apply average blur filter.

       The filter accepts the following options:

       sizeX
	   Set horizontal radius size.

       planes
	   Set which planes to filter. By default all planes are filtered.

       sizeY
	   Set vertical radius size, if zero it will be same as "sizeX".
	   Default is 0.

   bbox
       Compute the bounding box for the non-black pixels in the input frame
       luminance plane.

       This filter computes the bounding box containing all the pixels with a
       luminance value greater than the minimum allowed value.	The parameters
       describing the bounding box are printed on the filter log.

       The filter accepts the following option:

       min_val
	   Set the minimal luminance value. Default is 16.

   bitplanenoise
       Show and measure bit plane noise.

       The filter accepts the following options:

       bitplane
	   Set which plane to analyze. Default is 1.

       filter
	   Filter out noisy pixels from "bitplane" set above.  Default is
	   disabled.

   blackdetect
       Detect video intervals that are (almost) completely black. Can be
       useful to detect chapter transitions, commercials, or invalid
       recordings. Output lines contains the time for the start, end and
       duration of the detected black interval expressed in seconds.

       In order to display the output lines, you need to set the loglevel at
       least to the AV_LOG_INFO value.

       The filter accepts the following options:

       black_min_duration, d
	   Set the minimum detected black duration expressed in seconds. It
	   must be a non-negative floating point number.

	   Default value is 2.0.

       picture_black_ratio_th, pic_th
	   Set the threshold for considering a picture "black".  Express the
	   minimum value for the ratio:

		   <nb_black_pixels> / <nb_pixels>

	   for which a picture is considered black.  Default value is 0.98.

       pixel_black_th, pix_th
	   Set the threshold for considering a pixel "black".

	   The threshold expresses the maximum pixel luminance value for which
	   a pixel is considered "black". The provided value is scaled
	   according to the following equation:

		   <absolute_threshold> = <luminance_minimum_value> + <pixel_black_th> * <luminance_range_size>

	   luminance_range_size and luminance_minimum_value depend on the
	   input video format, the range is [0-255] for YUV full-range formats
	   and [16-235] for YUV non full-range formats.

	   Default value is 0.10.

       The following example sets the maximum pixel threshold to the minimum
       value, and detects only black intervals of 2 or more seconds:

	       blackdetect=d=2:pix_th=0.00

   blackframe
       Detect frames that are (almost) completely black. Can be useful to
       detect chapter transitions or commercials. Output lines consist of the
       frame number of the detected frame, the percentage of blackness, the
       position in the file if known or -1 and the timestamp in seconds.

       In order to display the output lines, you need to set the loglevel at
       least to the AV_LOG_INFO value.

       This filter exports frame metadata "lavfi.blackframe.pblack".  The
       value represents the percentage of pixels in the picture that are below
       the threshold value.

       It accepts the following parameters:

       amount
	   The percentage of the pixels that have to be below the threshold;
	   it defaults to 98.

       threshold, thresh
	   The threshold below which a pixel value is considered black; it
	   defaults to 32.

   blend, tblend
       Blend two video frames into each other.

       The "blend" filter takes two input streams and outputs one stream, the
       first input is the "top" layer and second input is "bottom" layer.  By
       default, the output terminates when the longest input terminates.

       The "tblend" (time blend) filter takes two consecutive frames from one
       single stream, and outputs the result obtained by blending the new
       frame on top of the old frame.

       A description of the accepted options follows.

       c0_mode
       c1_mode
       c2_mode
       c3_mode
       all_mode
	   Set blend mode for specific pixel component or all pixel components
	   in case of all_mode. Default value is "normal".

	   Available values for component modes are:

	   addition
	   grainmerge
	   and
	   average
	   burn
	   darken
	   difference
	   grainextract
	   divide
	   dodge
	   freeze
	   exclusion
	   extremity
	   glow
	   hardlight
	   hardmix
	   heat
	   lighten
	   linearlight
	   multiply
	   multiply128
	   negation
	   normal
	   or
	   overlay
	   phoenix
	   pinlight
	   reflect
	   screen
	   softlight
	   subtract
	   vividlight
	   xor
       c0_opacity
       c1_opacity
       c2_opacity
       c3_opacity
       all_opacity
	   Set blend opacity for specific pixel component or all pixel
	   components in case of all_opacity. Only used in combination with
	   pixel component blend modes.

       c0_expr
       c1_expr
       c2_expr
       c3_expr
       all_expr
	   Set blend expression for specific pixel component or all pixel
	   components in case of all_expr. Note that related mode options will
	   be ignored if those are set.

	   The expressions can use the following variables:

	   N   The sequential number of the filtered frame, starting from 0.

	   X
	   Y   the coordinates of the current sample

	   W
	   H   the width and height of currently filtered plane

	   SW
	   SH  Width and height scale for the plane being filtered. It is the
	       ratio between the dimensions of the current plane to the luma
	       plane, e.g. for a "yuv420p" frame, the values are "1,1" for the
	       luma plane and "0.5,0.5" for the chroma planes.

	   T   Time of the current frame, expressed in seconds.

	   TOP, A
	       Value of pixel component at current location for first video
	       frame (top layer).

	   BOTTOM, B
	       Value of pixel component at current location for second video
	       frame (bottom layer).

       The "blend" filter also supports the framesync options.

       Examples

       ·   Apply transition from bottom layer to top layer in first 10
	   seconds:

		   blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'

       ·   Apply linear horizontal transition from top layer to bottom layer:

		   blend=all_expr='A*(X/W)+B*(1-X/W)'

       ·   Apply 1x1 checkerboard effect:

		   blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'

       ·   Apply uncover left effect:

		   blend=all_expr='if(gte(N*SW+X,W),A,B)'

       ·   Apply uncover down effect:

		   blend=all_expr='if(gte(Y-N*SH,0),A,B)'

       ·   Apply uncover up-left effect:

		   blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'

       ·   Split diagonally video and shows top and bottom layer on each side:

		   blend=all_expr='if(gt(X,Y*(W/H)),A,B)'

       ·   Display differences between the current and the previous frame:

		   tblend=all_mode=grainextract

   boxblur
       Apply a boxblur algorithm to the input video.

       It accepts the following parameters:

       luma_radius, lr
       luma_power, lp
       chroma_radius, cr
       chroma_power, cp
       alpha_radius, ar
       alpha_power, ap

       A description of the accepted options follows.

       luma_radius, lr
       chroma_radius, cr
       alpha_radius, ar
	   Set an expression for the box radius in pixels used for blurring
	   the corresponding input plane.

	   The radius value must be a non-negative number, and must not be
	   greater than the value of the expression "min(w,h)/2" for the luma
	   and alpha planes, and of "min(cw,ch)/2" for the chroma planes.

	   Default value for luma_radius is "2". If not specified,
	   chroma_radius and alpha_radius default to the corresponding value
	   set for luma_radius.

	   The expressions can contain the following constants:

	   w
	   h   The input width and height in pixels.

	   cw
	   ch  The input chroma image width and height in pixels.

	   hsub
	   vsub
	       The horizontal and vertical chroma subsample values. For
	       example, for the pixel format "yuv422p", hsub is 2 and vsub is
	       1.

       luma_power, lp
       chroma_power, cp
       alpha_power, ap
	   Specify how many times the boxblur filter is applied to the
	   corresponding plane.

	   Default value for luma_power is 2. If not specified, chroma_power
	   and alpha_power default to the corresponding value set for
	   luma_power.

	   A value of 0 will disable the effect.

       Examples

       ·   Apply a boxblur filter with the luma, chroma, and alpha radii set
	   to 2:

		   boxblur=luma_radius=2:luma_power=1
		   boxblur=2:1

       ·   Set the luma radius to 2, and alpha and chroma radius to 0:

		   boxblur=2:1:cr=0:ar=0

       ·   Set the luma and chroma radii to a fraction of the video dimension:

		   boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1

   bwdif
       Deinterlace the input video ("bwdif" stands for "Bob Weaver
       Deinterlacing Filter").

       Motion adaptive deinterlacing based on yadif with the use of w3fdif and
       cubic interpolation algorithms.	It accepts the following parameters:

       mode
	   The interlacing mode to adopt. It accepts one of the following
	   values:

	   0, send_frame
	       Output one frame for each frame.

	   1, send_field
	       Output one frame for each field.

	   The default value is "send_field".

       parity
	   The picture field parity assumed for the input interlaced video. It
	   accepts one of the following values:

	   0, tff
	       Assume the top field is first.

	   1, bff
	       Assume the bottom field is first.

	   -1, auto
	       Enable automatic detection of field parity.

	   The default value is "auto".  If the interlacing is unknown or the
	   decoder does not export this information, top field first will be
	   assumed.

       deint
	   Specify which frames to deinterlace. Accept one of the following
	   values:

	   0, all
	       Deinterlace all frames.

	   1, interlaced
	       Only deinterlace frames marked as interlaced.

	   The default value is "all".

   chromakey
       YUV colorspace color/chroma keying.

       The filter accepts the following options:

       color
	   The color which will be replaced with transparency.

       similarity
	   Similarity percentage with the key color.

	   0.01 matches only the exact key color, while 1.0 matches
	   everything.

       blend
	   Blend percentage.

	   0.0 makes pixels either fully transparent, or not transparent at
	   all.

	   Higher values result in semi-transparent pixels, with a higher
	   transparency the more similar the pixels color is to the key color.

       yuv Signals that the color passed is already in YUV instead of RGB.

	   Literal colors like "green" or "red" don't make sense with this
	   enabled anymore.  This can be used to pass exact YUV values as
	   hexadecimal numbers.

       Examples

       ·   Make every green pixel in the input image transparent:

		   ffmpeg -i input.png -vf chromakey=green out.png

       ·   Overlay a greenscreen-video on top of a static black background.

		   ffmpeg -f lavfi -i color=c=black:s=1280x720 -i video.mp4 -shortest -filter_complex "[1:v]chromakey=0x70de77:0.1:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.mkv

   ciescope
       Display CIE color diagram with pixels overlaid onto it.

       The filter accepts the following options:

       system
	   Set color system.

	   ntsc, 470m
	   ebu, 470bg
	   smpte
	   240m
	   apple
	   widergb
	   cie1931
	   rec709, hdtv
	   uhdtv, rec2020
       cie Set CIE system.

	   xyy
	   ucs
	   luv
       gamuts
	   Set what gamuts to draw.

	   See "system" option for available values.

       size, s
	   Set ciescope size, by default set to 512.

       intensity, i
	   Set intensity used to map input pixel values to CIE diagram.

       contrast
	   Set contrast used to draw tongue colors that are out of active
	   color system gamut.

       corrgamma
	   Correct gamma displayed on scope, by default enabled.

       showwhite
	   Show white point on CIE diagram, by default disabled.

       gamma
	   Set input gamma. Used only with XYZ input color space.

   codecview
       Visualize information exported by some codecs.

       Some codecs can export information through frames using side-data or
       other means. For example, some MPEG based codecs export motion vectors
       through the export_mvs flag in the codec flags2 option.

       The filter accepts the following option:

       mv  Set motion vectors to visualize.

	   Available flags for mv are:

	   pf  forward predicted MVs of P-frames

	   bf  forward predicted MVs of B-frames

	   bb  backward predicted MVs of B-frames

       qp  Display quantization parameters using the chroma planes.

       mv_type, mvt
	   Set motion vectors type to visualize. Includes MVs from all frames
	   unless specified by frame_type option.

	   Available flags for mv_type are:

	   fp  forward predicted MVs

	   bp  backward predicted MVs

       frame_type, ft
	   Set frame type to visualize motion vectors of.

	   Available flags for frame_type are:

	   if  intra-coded frames (I-frames)

	   pf  predicted frames (P-frames)

	   bf  bi-directionally predicted frames (B-frames)

       Examples

       ·   Visualize forward predicted MVs of all frames using ffplay:

		   ffplay -flags2 +export_mvs input.mp4 -vf codecview=mv_type=fp

       ·   Visualize multi-directionals MVs of P and B-Frames using ffplay:

		   ffplay -flags2 +export_mvs input.mp4 -vf codecview=mv=pf+bf+bb

   colorbalance
       Modify intensity of primary colors (red, green and blue) of input
       frames.

       The filter allows an input frame to be adjusted in the shadows,
       midtones or highlights regions for the red-cyan, green-magenta or blue-
       yellow balance.

       A positive adjustment value shifts the balance towards the primary
       color, a negative value towards the complementary color.

       The filter accepts the following options:

       rs
       gs
       bs  Adjust red, green and blue shadows (darkest pixels).

       rm
       gm
       bm  Adjust red, green and blue midtones (medium pixels).

       rh
       gh
       bh  Adjust red, green and blue highlights (brightest pixels).

	   Allowed ranges for options are "[-1.0, 1.0]". Defaults are 0.

       Examples

       ·   Add red color cast to shadows:

		   colorbalance=rs=.3

   colorkey
       RGB colorspace color keying.

       The filter accepts the following options:

       color
	   The color which will be replaced with transparency.

       similarity
	   Similarity percentage with the key color.

	   0.01 matches only the exact key color, while 1.0 matches
	   everything.

       blend
	   Blend percentage.

	   0.0 makes pixels either fully transparent, or not transparent at
	   all.

	   Higher values result in semi-transparent pixels, with a higher
	   transparency the more similar the pixels color is to the key color.

       Examples

       ·   Make every green pixel in the input image transparent:

		   ffmpeg -i input.png -vf colorkey=green out.png

       ·   Overlay a greenscreen-video on top of a static background image.

		   ffmpeg -i background.png -i video.mp4 -filter_complex "[1:v]colorkey=0x3BBD1E:0.3:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.flv

   colorlevels
       Adjust video input frames using levels.

       The filter accepts the following options:

       rimin
       gimin
       bimin
       aimin
	   Adjust red, green, blue and alpha input black point.  Allowed
	   ranges for options are "[-1.0, 1.0]". Defaults are 0.

       rimax
       gimax
       bimax
       aimax
	   Adjust red, green, blue and alpha input white point.  Allowed
	   ranges for options are "[-1.0, 1.0]". Defaults are 1.

	   Input levels are used to lighten highlights (bright tones), darken
	   shadows (dark tones), change the balance of bright and dark tones.

       romin
       gomin
       bomin
       aomin
	   Adjust red, green, blue and alpha output black point.  Allowed
	   ranges for options are "[0, 1.0]". Defaults are 0.

       romax
       gomax
       bomax
       aomax
	   Adjust red, green, blue and alpha output white point.  Allowed
	   ranges for options are "[0, 1.0]". Defaults are 1.

	   Output levels allows manual selection of a constrained output level
	   range.

       Examples

       ·   Make video output darker:

		   colorlevels=rimin=0.058:gimin=0.058:bimin=0.058

       ·   Increase contrast:

		   colorlevels=rimin=0.039:gimin=0.039:bimin=0.039:rimax=0.96:gimax=0.96:bimax=0.96

       ·   Make video output lighter:

		   colorlevels=rimax=0.902:gimax=0.902:bimax=0.902

       ·   Increase brightness:

		   colorlevels=romin=0.5:gomin=0.5:bomin=0.5

   colorchannelmixer
       Adjust video input frames by re-mixing color channels.

       This filter modifies a color channel by adding the values associated to
       the other channels of the same pixels. For example if the value to
       modify is red, the output value will be:

	       <red>=<red>*<rr> + <blue>*<rb> + <green>*<rg> + <alpha>*<ra>

       The filter accepts the following options:

       rr
       rg
       rb
       ra  Adjust contribution of input red, green, blue and alpha channels
	   for output red channel.  Default is 1 for rr, and 0 for rg, rb and
	   ra.

       gr
       gg
       gb
       ga  Adjust contribution of input red, green, blue and alpha channels
	   for output green channel.  Default is 1 for gg, and 0 for gr, gb
	   and ga.

       br
       bg
       bb
       ba  Adjust contribution of input red, green, blue and alpha channels
	   for output blue channel.  Default is 1 for bb, and 0 for br, bg and
	   ba.

       ar
       ag
       ab
       aa  Adjust contribution of input red, green, blue and alpha channels
	   for output alpha channel.  Default is 1 for aa, and 0 for ar, ag
	   and ab.

	   Allowed ranges for options are "[-2.0, 2.0]".

       Examples

       ·   Convert source to grayscale:

		   colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3

       ·   Simulate sepia tones:

		   colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131

   colormatrix
       Convert color matrix.

       The filter accepts the following options:

       src
       dst Specify the source and destination color matrix. Both values must
	   be specified.

	   The accepted values are:

	   bt709
	       BT.709

	   fcc FCC

	   bt601
	       BT.601

	   bt470
	       BT.470

	   bt470bg
	       BT.470BG

	   smpte170m
	       SMPTE-170M

	   smpte240m
	       SMPTE-240M

	   bt2020
	       BT.2020

       For example to convert from BT.601 to SMPTE-240M, use the command:

	       colormatrix=bt601:smpte240m

   colorspace
       Convert colorspace, transfer characteristics or color primaries.  Input
       video needs to have an even size.

       The filter accepts the following options:

       all Specify all color properties at once.

	   The accepted values are:

	   bt470m
	       BT.470M

	   bt470bg
	       BT.470BG

	   bt601-6-525
	       BT.601-6 525

	   bt601-6-625
	       BT.601-6 625

	   bt709
	       BT.709

	   smpte170m
	       SMPTE-170M

	   smpte240m
	       SMPTE-240M

	   bt2020
	       BT.2020

       space
	   Specify output colorspace.

	   The accepted values are:

	   bt709
	       BT.709

	   fcc FCC

	   bt470bg
	       BT.470BG or BT.601-6 625

	   smpte170m
	       SMPTE-170M or BT.601-6 525

	   smpte240m
	       SMPTE-240M

	   ycgco
	       YCgCo

	   bt2020ncl
	       BT.2020 with non-constant luminance

       trc Specify output transfer characteristics.

	   The accepted values are:

	   bt709
	       BT.709

	   bt470m
	       BT.470M

	   bt470bg
	       BT.470BG

	   gamma22
	       Constant gamma of 2.2

	   gamma28
	       Constant gamma of 2.8

	   smpte170m
	       SMPTE-170M, BT.601-6 625 or BT.601-6 525

	   smpte240m
	       SMPTE-240M

	   srgb
	       SRGB

	   iec61966-2-1
	       iec61966-2-1

	   iec61966-2-4
	       iec61966-2-4

	   xvycc
	       xvycc

	   bt2020-10
	       BT.2020 for 10-bits content

	   bt2020-12
	       BT.2020 for 12-bits content

       primaries
	   Specify output color primaries.

	   The accepted values are:

	   bt709
	       BT.709

	   bt470m
	       BT.470M

	   bt470bg
	       BT.470BG or BT.601-6 625

	   smpte170m
	       SMPTE-170M or BT.601-6 525

	   smpte240m
	       SMPTE-240M

	   film
	       film

	   smpte431
	       SMPTE-431

	   smpte432
	       SMPTE-432

	   bt2020
	       BT.2020

	   jedec-p22
	       JEDEC P22 phosphors

       range
	   Specify output color range.

	   The accepted values are:

	   tv  TV (restricted) range

	   mpeg
	       MPEG (restricted) range

	   pc  PC (full) range

	   jpeg
	       JPEG (full) range

       format
	   Specify output color format.

	   The accepted values are:

	   yuv420p
	       YUV 4:2:0 planar 8-bits

	   yuv420p10
	       YUV 4:2:0 planar 10-bits

	   yuv420p12
	       YUV 4:2:0 planar 12-bits

	   yuv422p
	       YUV 4:2:2 planar 8-bits

	   yuv422p10
	       YUV 4:2:2 planar 10-bits

	   yuv422p12
	       YUV 4:2:2 planar 12-bits

	   yuv444p
	       YUV 4:4:4 planar 8-bits

	   yuv444p10
	       YUV 4:4:4 planar 10-bits

	   yuv444p12
	       YUV 4:4:4 planar 12-bits

       fast
	   Do a fast conversion, which skips gamma/primary correction. This
	   will take significantly less CPU, but will be mathematically
	   incorrect. To get output compatible with that produced by the
	   colormatrix filter, use fast=1.

       dither
	   Specify dithering mode.

	   The accepted values are:

	   none
	       No dithering

	   fsb Floyd-Steinberg dithering

       wpadapt
	   Whitepoint adaptation mode.

	   The accepted values are:

	   bradford
	       Bradford whitepoint adaptation

	   vonkries
	       von Kries whitepoint adaptation

	   identity
	       identity whitepoint adaptation (i.e. no whitepoint adaptation)

       iall
	   Override all input properties at once. Same accepted values as all.

       ispace
	   Override input colorspace. Same accepted values as space.

       iprimaries
	   Override input color primaries. Same accepted values as primaries.

       itrc
	   Override input transfer characteristics. Same accepted values as
	   trc.

       irange
	   Override input color range. Same accepted values as range.

       The filter converts the transfer characteristics, color space and color
       primaries to the specified user values. The output value, if not
       specified, is set to a default value based on the "all" property. If
       that property is also not specified, the filter will log an error. The
       output color range and format default to the same value as the input
       color range and format. The input transfer characteristics, color
       space, color primaries and color range should be set on the input data.
       If any of these are missing, the filter will log an error and no
       conversion will take place.

       For example to convert the input to SMPTE-240M, use the command:

	       colorspace=smpte240m

   convolution
       Apply convolution of 3x3, 5x5, 7x7 or horizontal/vertical up to 49
       elements.

       The filter accepts the following options:

       0m
       1m
       2m
       3m  Set matrix for each plane.  Matrix is sequence of 9, 25 or 49
	   signed integers in square mode, and from 1 to 49 odd number of
	   signed integers in row mode.

       0rdiv
       1rdiv
       2rdiv
       3rdiv
	   Set multiplier for calculated value for each plane.	If unset or 0,
	   it will be sum of all matrix elements.

       0bias
       1bias
       2bias
       3bias
	   Set bias for each plane. This value is added to the result of the
	   multiplication.  Useful for making the overall image brighter or
	   darker. Default is 0.0.

       0mode
       1mode
       2mode
       3mode
	   Set matrix mode for each plane. Can be square, row or column.
	   Default is square.

       Examples

       ·   Apply sharpen:

		   convolution="0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0"

       ·   Apply blur:

		   convolution="1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1/9:1/9:1/9:1/9"

       ·   Apply edge enhance:

		   convolution="0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:5:1:1:1:0:128:128:128"

       ·   Apply edge detect:

		   convolution="0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:5:5:5:1:0:128:128:128"

       ·   Apply laplacian edge detector which includes diagonals:

		   convolution="1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:5:5:5:1:0:128:128:0"

       ·   Apply emboss:

		   convolution="-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2"

   convolve
       Apply 2D convolution of video stream in frequency domain using second
       stream as impulse.

       The filter accepts the following options:

       planes
	   Set which planes to process.

       impulse
	   Set which impulse video frames will be processed, can be first or
	   all. Default is all.

       The "convolve" filter also supports the framesync options.

   copy
       Copy the input video source unchanged to the output. This is mainly
       useful for testing purposes.

   coreimage
       Video filtering on GPU using Apple's CoreImage API on OSX.

       Hardware acceleration is based on an OpenGL context. Usually, this
       means it is processed by video hardware. However, software-based OpenGL
       implementations exist which means there is no guarantee for hardware
       processing. It depends on the respective OSX.

       There are many filters and image generators provided by Apple that come
       with a large variety of options. The filter has to be referenced by its
       name along with its options.

       The coreimage filter accepts the following options:

       list_filters
	   List all available filters and generators along with all their
	   respective options as well as possible minimum and maximum values
	   along with the default values.

		   list_filters=true

       filter
	   Specify all filters by their respective name and options.  Use
	   list_filters to determine all valid filter names and options.
	   Numerical options are specified by a float value and are
	   automatically clamped to their respective value range.  Vector and
	   color options have to be specified by a list of space separated
	   float values. Character escaping has to be done.  A special option
	   name "default" is available to use default options for a filter.

	   It is required to specify either "default" or at least one of the
	   filter options.  All omitted options are used with their default
	   values.  The syntax of the filter string is as follows:

		   filter=<NAME>@<OPTION>=<VALUE>[@<OPTION>=<VALUE>][@...][#<NAME>@<OPTION>=<VALUE>[@<OPTION>=<VALUE>][@...]][#...]

       output_rect
	   Specify a rectangle where the output of the filter chain is copied
	   into the input image. It is given by a list of space separated
	   float values:

		   output_rect=x\ y\ width\ height

	   If not given, the output rectangle equals the dimensions of the
	   input image.  The output rectangle is automatically cropped at the
	   borders of the input image. Negative values are valid for each
	   component.

		   output_rect=25\ 25\ 100\ 100

       Several filters can be chained for successive processing without GPU-
       HOST transfers allowing for fast processing of complex filter chains.
       Currently, only filters with zero (generators) or exactly one (filters)
       input image and one output image are supported. Also, transition
       filters are not yet usable as intended.

       Some filters generate output images with additional padding depending
       on the respective filter kernel. The padding is automatically removed
       to ensure the filter output has the same size as the input image.

       For image generators, the size of the output image is determined by the
       previous output image of the filter chain or the input image of the
       whole filterchain, respectively. The generators do not use the pixel
       information of this image to generate their output. However, the
       generated output is blended onto this image, resulting in partial or
       complete coverage of the output image.

       The coreimagesrc video source can be used for generating input images
       which are directly fed into the filter chain. By using it, providing
       input images by another video source or an input video is not required.

       Examples

       ·   List all filters available:

		   coreimage=list_filters=true

       ·   Use the CIBoxBlur filter with default options to blur an image:

		   coreimage=filter=CIBoxBlur@default

       ·   Use a filter chain with CISepiaTone at default values and
	   CIVignetteEffect with its center at 100x100 and a radius of 50
	   pixels:

		   coreimage=filter=CIBoxBlur@default#CIVignetteEffect@inputCenter=100\ 100@inputRadius=50

       ·   Use nullsrc and CIQRCodeGenerator to create a QR code for the
	   FFmpeg homepage, given as complete and escaped command-line for
	   Apple's standard bash shell:

		   ffmpeg -f lavfi -i nullsrc=s=100x100,coreimage=filter=CIQRCodeGenerator@inputMessage=https\\\\\://FFmpeg.org/@inputCorrectionLevel=H -frames:v 1 QRCode.png

   crop
       Crop the input video to given dimensions.

       It accepts the following parameters:

       w, out_w
	   The width of the output video. It defaults to "iw".	This
	   expression is evaluated only once during the filter configuration,
	   or when the w or out_w command is sent.

       h, out_h
	   The height of the output video. It defaults to "ih".  This
	   expression is evaluated only once during the filter configuration,
	   or when the h or out_h command is sent.

       x   The horizontal position, in the input video, of the left edge of
	   the output video. It defaults to "(in_w-out_w)/2".  This expression
	   is evaluated per-frame.

       y   The vertical position, in the input video, of the top edge of the
	   output video.  It defaults to "(in_h-out_h)/2".  This expression is
	   evaluated per-frame.

       keep_aspect
	   If set to 1 will force the output display aspect ratio to be the
	   same of the input, by changing the output sample aspect ratio. It
	   defaults to 0.

       exact
	   Enable exact cropping. If enabled, subsampled videos will be
	   cropped at exact width/height/x/y as specified and will not be
	   rounded to nearest smaller value.  It defaults to 0.

       The out_w, out_h, x, y parameters are expressions containing the
       following constants:

       x
       y   The computed values for x and y. They are evaluated for each new
	   frame.

       in_w
       in_h
	   The input width and height.

       iw
       ih  These are the same as in_w and in_h.

       out_w
       out_h
	   The output (cropped) width and height.

       ow
       oh  These are the same as out_w and out_h.

       a   same as iw / ih

       sar input sample aspect ratio

       dar input display aspect ratio, it is the same as (iw / ih) * sar

       hsub
       vsub
	   horizontal and vertical chroma subsample values. For example for
	   the pixel format "yuv422p" hsub is 2 and vsub is 1.

       n   The number of the input frame, starting from 0.

       pos the position in the file of the input frame, NAN if unknown

       t   The timestamp expressed in seconds. It's NAN if the input timestamp
	   is unknown.

       The expression for out_w may depend on the value of out_h, and the
       expression for out_h may depend on out_w, but they cannot depend on x
       and y, as x and y are evaluated after out_w and out_h.

       The x and y parameters specify the expressions for the position of the
       top-left corner of the output (non-cropped) area. They are evaluated
       for each frame. If the evaluated value is not valid, it is approximated
       to the nearest valid value.

       The expression for x may depend on y, and the expression for y may
       depend on x.

       Examples

       ·   Crop area with size 100x100 at position (12,34).

		   crop=100:100:12:34

	   Using named options, the example above becomes:

		   crop=w=100:h=100:x=12:y=34

       ·   Crop the central input area with size 100x100:

		   crop=100:100

       ·   Crop the central input area with size 2/3 of the input video:

		   crop=2/3*in_w:2/3*in_h

       ·   Crop the input video central square:

		   crop=out_w=in_h
		   crop=in_h

       ·   Delimit the rectangle with the top-left corner placed at position
	   100:100 and the right-bottom corner corresponding to the right-
	   bottom corner of the input image.

		   crop=in_w-100:in_h-100:100:100

       ·   Crop 10 pixels from the left and right borders, and 20 pixels from
	   the top and bottom borders

		   crop=in_w-2*10:in_h-2*20

       ·   Keep only the bottom right quarter of the input image:

		   crop=in_w/2:in_h/2:in_w/2:in_h/2

       ·   Crop height for getting Greek harmony:

		   crop=in_w:1/PHI*in_w

       ·   Apply trembling effect:

		   crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)

       ·   Apply erratic camera effect depending on timestamp:

		   crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"

       ·   Set x depending on the value of y:

		   crop=in_w/2:in_h/2:y:10+10*sin(n/10)

       Commands

       This filter supports the following commands:

       w, out_w
       h, out_h
       x
       y   Set width/height of the output video and the horizontal/vertical
	   position in the input video.  The command accepts the same syntax
	   of the corresponding option.

	   If the specified expression is not valid, it is kept at its current
	   value.

   cropdetect
       Auto-detect the crop size.

       It calculates the necessary cropping parameters and prints the
       recommended parameters via the logging system. The detected dimensions
       correspond to the non-black area of the input video.

       It accepts the following parameters:

       limit
	   Set higher black value threshold, which can be optionally specified
	   from nothing (0) to everything (255 for 8-bit based formats). An
	   intensity value greater to the set value is considered non-black.
	   It defaults to 24.  You can also specify a value between 0.0 and
	   1.0 which will be scaled depending on the bitdepth of the pixel
	   format.

       round
	   The value which the width/height should be divisible by. It
	   defaults to 16. The offset is automatically adjusted to center the
	   video. Use 2 to get only even dimensions (needed for 4:2:2 video).
	   16 is best when encoding to most video codecs.

       reset_count, reset
	   Set the counter that determines after how many frames cropdetect
	   will reset the previously detected largest video area and start
	   over to detect the current optimal crop area. Default value is 0.

	   This can be useful when channel logos distort the video area. 0
	   indicates 'never reset', and returns the largest area encountered
	   during playback.

   curves
       Apply color adjustments using curves.

       This filter is similar to the Adobe Photoshop and GIMP curves tools.
       Each component (red, green and blue) has its values defined by N key
       points tied from each other using a smooth curve. The x-axis represents
       the pixel values from the input frame, and the y-axis the new pixel
       values to be set for the output frame.

       By default, a component curve is defined by the two points (0;0) and
       (1;1). This creates a straight line where each original pixel value is
       "adjusted" to its own value, which means no change to the image.

       The filter allows you to redefine these two points and add some more. A
       new curve (using a natural cubic spline interpolation) will be define
       to pass smoothly through all these new coordinates. The new defined
       points needs to be strictly increasing over the x-axis, and their x and
       y values must be in the [0;1] interval.	If the computed curves
       happened to go outside the vector spaces, the values will be clipped
       accordingly.

       The filter accepts the following options:

       preset
	   Select one of the available color presets. This option can be used
	   in addition to the r, g, b parameters; in this case, the later
	   options takes priority on the preset values.  Available presets
	   are:

	   none
	   color_negative
	   cross_process
	   darker
	   increase_contrast
	   lighter
	   linear_contrast
	   medium_contrast
	   negative
	   strong_contrast
	   vintage

	   Default is "none".

       master, m
	   Set the master key points. These points will define a second pass
	   mapping. It is sometimes called a "luminance" or "value" mapping.
	   It can be used with r, g, b or all since it acts like a post-
	   processing LUT.

       red, r
	   Set the key points for the red component.

       green, g
	   Set the key points for the green component.

       blue, b
	   Set the key points for the blue component.

       all Set the key points for all components (not including master).  Can
	   be used in addition to the other key points component options. In
	   this case, the unset component(s) will fallback on this all
	   setting.

       psfile
	   Specify a Photoshop curves file (".acv") to import the settings
	   from.

       plot
	   Save Gnuplot script of the curves in specified file.

       To avoid some filtergraph syntax conflicts, each key points list need
       to be defined using the following syntax: "x0/y0 x1/y1 x2/y2 ...".

       Examples

       ·   Increase slightly the middle level of blue:

		   curves=blue='0/0 0.5/0.58 1/1'

       ·   Vintage effect:

		   curves=r='0/0.11 .42/.51 1/0.95':g='0/0 0.50/0.48 1/1':b='0/0.22 .49/.44 1/0.8'

	   Here we obtain the following coordinates for each components:

	   red "(0;0.11) (0.42;0.51) (1;0.95)"

	   green
	       "(0;0) (0.50;0.48) (1;1)"

	   blue
	       "(0;0.22) (0.49;0.44) (1;0.80)"

       ·   The previous example can also be achieved with the associated
	   built-in preset:

		   curves=preset=vintage

       ·   Or simply:

		   curves=vintage

       ·   Use a Photoshop preset and redefine the points of the green
	   component:

		   curves=psfile='MyCurvesPresets/purple.acv':green='0/0 0.45/0.53 1/1'

       ·   Check out the curves of the "cross_process" profile using ffmpeg
	   and gnuplot:

		   ffmpeg -f lavfi -i color -vf curves=cross_process:plot=/tmp/curves.plt -frames:v 1 -f null -
		   gnuplot -p /tmp/curves.plt

   datascope
       Video data analysis filter.

       This filter shows hexadecimal pixel values of part of video.

       The filter accepts the following options:

       size, s
	   Set output video size.

       x   Set x offset from where to pick pixels.

       y   Set y offset from where to pick pixels.

       mode
	   Set scope mode, can be one of the following:

	   mono
	       Draw hexadecimal pixel values with white color on black
	       background.

	   color
	       Draw hexadecimal pixel values with input video pixel color on
	       black background.

	   color2
	       Draw hexadecimal pixel values on color background picked from
	       input video, the text color is picked in such way so its always
	       visible.

       axis
	   Draw rows and columns numbers on left and top of video.

       opacity
	   Set background opacity.

   dctdnoiz
       Denoise frames using 2D DCT (frequency domain filtering).

       This filter is not designed for real time.

       The filter accepts the following options:

       sigma, s
	   Set the noise sigma constant.

	   This sigma defines a hard threshold of "3 * sigma"; every DCT
	   coefficient (absolute value) below this threshold with be dropped.

	   If you need a more advanced filtering, see expr.

	   Default is 0.

       overlap
	   Set number overlapping pixels for each block. Since the filter can
	   be slow, you may want to reduce this value, at the cost of a less
	   effective filter and the risk of various artefacts.

	   If the overlapping value doesn't permit processing the whole input
	   width or height, a warning will be displayed and according borders
	   won't be denoised.

	   Default value is blocksize-1, which is the best possible setting.

       expr, e
	   Set the coefficient factor expression.

	   For each coefficient of a DCT block, this expression will be
	   evaluated as a multiplier value for the coefficient.

	   If this is option is set, the sigma option will be ignored.

	   The absolute value of the coefficient can be accessed through the c
	   variable.

       n   Set the blocksize using the number of bits. "1<<n" defines the
	   blocksize, which is the width and height of the processed blocks.

	   The default value is 3 (8x8) and can be raised to 4 for a blocksize
	   of 16x16. Note that changing this setting has huge consequences on
	   the speed processing. Also, a larger block size does not
	   necessarily means a better de-noising.

       Examples

       Apply a denoise with a sigma of 4.5:

	       dctdnoiz=4.5

       The same operation can be achieved using the expression system:

	       dctdnoiz=e='gte(c, 4.5*3)'

       Violent denoise using a block size of "16x16":

	       dctdnoiz=15:n=4

   deband
       Remove banding artifacts from input video.  It works by replacing
       banded pixels with average value of referenced pixels.

       The filter accepts the following options:

       1thr
       2thr
       3thr
       4thr
	   Set banding detection threshold for each plane. Default is 0.02.
	   Valid range is 0.00003 to 0.5.  If difference between current pixel
	   and reference pixel is less than threshold, it will be considered
	   as banded.

       range, r
	   Banding detection range in pixels. Default is 16. If positive,
	   random number in range 0 to set value will be used. If negative,
	   exact absolute value will be used.  The range defines square of
	   four pixels around current pixel.

       direction, d
	   Set direction in radians from which four pixel will be compared. If
	   positive, random direction from 0 to set direction will be picked.
	   If negative, exact of absolute value will be picked. For example
	   direction 0, -PI or -2*PI radians will pick only pixels on same row
	   and -PI/2 will pick only pixels on same column.

       blur, b
	   If enabled, current pixel is compared with average value of all
	   four surrounding pixels. The default is enabled. If disabled
	   current pixel is compared with all four surrounding pixels. The
	   pixel is considered banded if only all four differences with
	   surrounding pixels are less than threshold.

       coupling, c
	   If enabled, current pixel is changed if and only if all pixel
	   components are banded, e.g. banding detection threshold is
	   triggered for all color components.	The default is disabled.

   deblock
       Remove blocking artifacts from input video.

       The filter accepts the following options:

       filter
	   Set filter type, can be weak or strong. Default is strong.  This
	   controls what kind of deblocking is applied.

       block
	   Set size of block, allowed range is from 4 to 512. Default is 8.

       alpha
       beta
       gamma
       delta
	   Set blocking detection thresholds. Allowed range is 0 to 1.
	   Defaults are: 0.098 for alpha and 0.05 for the rest.  Using higher
	   threshold gives more deblocking strength.  Setting alpha controls
	   threshold detection at exact edge of block.	Remaining options
	   controls threshold detection near the edge. Each one for
	   below/above or left/right. Setting any of those to 0 disables
	   deblocking.

       planes
	   Set planes to filter. Default is to filter all available planes.

       Examples

       ·   Deblock using weak filter and block size of 4 pixels.

		   deblock=filter=weak:block=4

       ·   Deblock using strong filter, block size of 4 pixels and custom
	   thresholds for deblocking more edges.

		   deblock=filter=strong:block=4:alpha=0.12:beta=0.07:gamma=0.06:delta=0.05

       ·   Similar as above, but filter only first plane.

		   deblock=filter=strong:block=4:alpha=0.12:beta=0.07:gamma=0.06:delta=0.05:planes=1

       ·   Similar as above, but filter only second and third plane.

		   deblock=filter=strong:block=4:alpha=0.12:beta=0.07:gamma=0.06:delta=0.05:planes=6

   decimate
       Drop duplicated frames at regular intervals.

       The filter accepts the following options:

       cycle
	   Set the number of frames from which one will be dropped. Setting
	   this to N means one frame in every batch of N frames will be
	   dropped.  Default is 5.

       dupthresh
	   Set the threshold for duplicate detection. If the difference metric
	   for a frame is less than or equal to this value, then it is
	   declared as duplicate. Default is 1.1

       scthresh
	   Set scene change threshold. Default is 15.

       blockx
       blocky
	   Set the size of the x and y-axis blocks used during metric
	   calculations.  Larger blocks give better noise suppression, but
	   also give worse detection of small movements. Must be a power of
	   two. Default is 32.

       ppsrc
	   Mark main input as a pre-processed input and activate clean source
	   input stream. This allows the input to be pre-processed with
	   various filters to help the metrics calculation while keeping the
	   frame selection lossless. When set to 1, the first stream is for
	   the pre-processed input, and the second stream is the clean source
	   from where the kept frames are chosen. Default is 0.

       chroma
	   Set whether or not chroma is considered in the metric calculations.
	   Default is 1.

   deconvolve
       Apply 2D deconvolution of video stream in frequency domain using second
       stream as impulse.

       The filter accepts the following options:

       planes
	   Set which planes to process.

       impulse
	   Set which impulse video frames will be processed, can be first or
	   all. Default is all.

       noise
	   Set noise when doing divisions. Default is 0.0000001. Useful when
	   width and height are not same and not power of 2 or if stream prior
	   to convolving had noise.

       The "deconvolve" filter also supports the framesync options.

   deflate
       Apply deflate effect to the video.

       This filter replaces the pixel by the local(3x3) average by taking into
       account only values lower than the pixel.

       It accepts the following options:

       threshold0
       threshold1
       threshold2
       threshold3
	   Limit the maximum change for each plane, default is 65535.  If 0,
	   plane will remain unchanged.

   deflicker
       Remove temporal frame luminance variations.

       It accepts the following options:

       size, s
	   Set moving-average filter size in frames. Default is 5. Allowed
	   range is 2 - 129.

       mode, m
	   Set averaging mode to smooth temporal luminance variations.

	   Available values are:

	   am  Arithmetic mean

	   gm  Geometric mean

	   hm  Harmonic mean

	   qm  Quadratic mean

	   cm  Cubic mean

	   pm  Power mean

	   median
	       Median

       bypass
	   Do not actually modify frame. Useful when one only wants metadata.

   dejudder
       Remove judder produced by partially interlaced telecined content.

       Judder can be introduced, for instance, by pullup filter. If the
       original source was partially telecined content then the output of
       "pullup,dejudder" will have a variable frame rate. May change the
       recorded frame rate of the container. Aside from that change, this
       filter will not affect constant frame rate video.

       The option available in this filter is:

       cycle
	   Specify the length of the window over which the judder repeats.

	   Accepts any integer greater than 1. Useful values are:

	   4   If the original was telecined from 24 to 30 fps (Film to NTSC).

	   5   If the original was telecined from 25 to 30 fps (PAL to NTSC).

	   20  If a mixture of the two.

	   The default is 4.

   delogo
       Suppress a TV station logo by a simple interpolation of the surrounding
       pixels. Just set a rectangle covering the logo and watch it disappear
       (and sometimes something even uglier appear - your mileage may vary).

       It accepts the following parameters:

       x
       y   Specify the top left corner coordinates of the logo. They must be
	   specified.

       w
       h   Specify the width and height of the logo to clear. They must be
	   specified.

       band, t
	   Specify the thickness of the fuzzy edge of the rectangle (added to
	   w and h). The default value is 1. This option is deprecated,
	   setting higher values should no longer be necessary and is not
	   recommended.

       show
	   When set to 1, a green rectangle is drawn on the screen to simplify
	   finding the right x, y, w, and h parameters.  The default value is
	   0.

	   The rectangle is drawn on the outermost pixels which will be
	   (partly) replaced with interpolated values. The values of the next
	   pixels immediately outside this rectangle in each direction will be
	   used to compute the interpolated pixel values inside the rectangle.

       Examples

       ·   Set a rectangle covering the area with top left corner coordinates
	   0,0 and size 100x77, and a band of size 10:

		   delogo=x=0:y=0:w=100:h=77:band=10

   deshake
       Attempt to fix small changes in horizontal and/or vertical shift. This
       filter helps remove camera shake from hand-holding a camera, bumping a
       tripod, moving on a vehicle, etc.

       The filter accepts the following options:

       x
       y
       w
       h   Specify a rectangular area where to limit the search for motion
	   vectors.  If desired the search for motion vectors can be limited
	   to a rectangular area of the frame defined by its top left corner,
	   width and height. These parameters have the same meaning as the
	   drawbox filter which can be used to visualise the position of the
	   bounding box.

	   This is useful when simultaneous movement of subjects within the
	   frame might be confused for camera motion by the motion vector
	   search.

	   If any or all of x, y, w and h are set to -1 then the full frame is
	   used. This allows later options to be set without specifying the
	   bounding box for the motion vector search.

	   Default - search the whole frame.

       rx
       ry  Specify the maximum extent of movement in x and y directions in the
	   range 0-64 pixels. Default 16.

       edge
	   Specify how to generate pixels to fill blanks at the edge of the
	   frame. Available values are:

	   blank, 0
	       Fill zeroes at blank locations

	   original, 1
	       Original image at blank locations

	   clamp, 2
	       Extruded edge value at blank locations

	   mirror, 3
	       Mirrored edge at blank locations

	   Default value is mirror.

       blocksize
	   Specify the blocksize to use for motion search. Range 4-128 pixels,
	   default 8.

       contrast
	   Specify the contrast threshold for blocks. Only blocks with more
	   than the specified contrast (difference between darkest and
	   lightest pixels) will be considered. Range 1-255, default 125.

       search
	   Specify the search strategy. Available values are:

	   exhaustive, 0
	       Set exhaustive search

	   less, 1
	       Set less exhaustive search.

	   Default value is exhaustive.

       filename
	   If set then a detailed log of the motion search is written to the
	   specified file.

   despill
       Remove unwanted contamination of foreground colors, caused by reflected
       color of greenscreen or bluescreen.

       This filter accepts the following options:

       type
	   Set what type of despill to use.

       mix Set how spillmap will be generated.

       expand
	   Set how much to get rid of still remaining spill.

       red Controls amount of red in spill area.

       green
	   Controls amount of green in spill area.  Should be -1 for
	   greenscreen.

       blue
	   Controls amount of blue in spill area.  Should be -1 for
	   bluescreen.

       brightness
	   Controls brightness of spill area, preserving colors.

       alpha
	   Modify alpha from generated spillmap.

   detelecine
       Apply an exact inverse of the telecine operation. It requires a
       predefined pattern specified using the pattern option which must be the
       same as that passed to the telecine filter.

       This filter accepts the following options:

       first_field
	   top, t
	       top field first

	   bottom, b
	       bottom field first The default value is "top".

       pattern
	   A string of numbers representing the pulldown pattern you wish to
	   apply.  The default value is 23.

       start_frame
	   A number representing position of the first frame with respect to
	   the telecine pattern. This is to be used if the stream is cut. The
	   default value is 0.

   dilation
       Apply dilation effect to the video.

       This filter replaces the pixel by the local(3x3) maximum.

       It accepts the following options:

       threshold0
       threshold1
       threshold2
       threshold3
	   Limit the maximum change for each plane, default is 65535.  If 0,
	   plane will remain unchanged.

       coordinates
	   Flag which specifies the pixel to refer to. Default is 255 i.e. all
	   eight pixels are used.

	   Flags to local 3x3 coordinates maps like this:

	       1 2 3
	       4   5
	       6 7 8

   displace
       Displace pixels as indicated by second and third input stream.

       It takes three input streams and outputs one stream, the first input is
       the source, and second and third input are displacement maps.

       The second input specifies how much to displace pixels along the
       x-axis, while the third input specifies how much to displace pixels
       along the y-axis.  If one of displacement map streams terminates, last
       frame from that displacement map will be used.

       Note that once generated, displacements maps can be reused over and
       over again.

       A description of the accepted options follows.

       edge
	   Set displace behavior for pixels that are out of range.

	   Available values are:

	   blank
	       Missing pixels are replaced by black pixels.

	   smear
	       Adjacent pixels will spread out to replace missing pixels.

	   wrap
	       Out of range pixels are wrapped so they point to pixels of
	       other side.

	   mirror
	       Out of range pixels will be replaced with mirrored pixels.

	   Default is smear.

       Examples

       ·   Add ripple effect to rgb input of video size hd720:

		   ffmpeg -i INPUT -f lavfi -i nullsrc=s=hd720,lutrgb=128:128:128 -f lavfi -i nullsrc=s=hd720,geq='r=128+30*sin(2*PI*X/400+T):g=128+30*sin(2*PI*X/400+T):b=128+30*sin(2*PI*X/400+T)' -lavfi '[0][1][2]displace' OUTPUT

       ·   Add wave effect to rgb input of video size hd720:

		   ffmpeg -i INPUT -f lavfi -i nullsrc=hd720,geq='r=128+80*(sin(sqrt((X-W/2)*(X-W/2)+(Y-H/2)*(Y-H/2))/220*2*PI+T)):g=128+80*(sin(sqrt((X-W/2)*(X-W/2)+(Y-H/2)*(Y-H/2))/220*2*PI+T)):b=128+80*(sin(sqrt((X-W/2)*(X-W/2)+(Y-H/2)*(Y-H/2))/220*2*PI+T))' -lavfi '[1]split[x][y],[0][x][y]displace' OUTPUT

   drawbox
       Draw a colored box on the input image.

       It accepts the following parameters:

       x
       y   The expressions which specify the top left corner coordinates of
	   the box. It defaults to 0.

       width, w
       height, h
	   The expressions which specify the width and height of the box; if 0
	   they are interpreted as the input width and height. It defaults to
	   0.

       color, c
	   Specify the color of the box to write. For the general syntax of
	   this option, check the "Color" section in the ffmpeg-utils manual.
	   If the special value "invert" is used, the box edge color is the
	   same as the video with inverted luma.

       thickness, t
	   The expression which sets the thickness of the box edge.  A value
	   of "fill" will create a filled box. Default value is 3.

	   See below for the list of accepted constants.

       replace
	   Applicable if the input has alpha. With value 1, the pixels of the
	   painted box will overwrite the video's color and alpha pixels.
	   Default is 0, which composites the box onto the input, leaving the
	   video's alpha intact.

       The parameters for x, y, w and h and t are expressions containing the
       following constants:

       dar The input display aspect ratio, it is the same as (w / h) * sar.

       hsub
       vsub
	   horizontal and vertical chroma subsample values. For example for
	   the pixel format "yuv422p" hsub is 2 and vsub is 1.

       in_h, ih
       in_w, iw
	   The input width and height.

       sar The input sample aspect ratio.

       x
       y   The x and y offset coordinates where the box is drawn.

       w
       h   The width and height of the drawn box.

       t   The thickness of the drawn box.

	   These constants allow the x, y, w, h and t expressions to refer to
	   each other, so you may for example specify "y=x/dar" or "h=w/dar".

       Examples

       ·   Draw a black box around the edge of the input image:

		   drawbox

       ·   Draw a box with color red and an opacity of 50%:

		   drawbox=10:20:200:60:red@0.5

	   The previous example can be specified as:

		   drawbox=x=10:y=20:w=200:h=60:color=red@0.5

       ·   Fill the box with pink color:

		   drawbox=x=10:y=10:w=100:h=100:color=pink@0.5:t=fill

       ·   Draw a 2-pixel red 2.40:1 mask:

		   drawbox=x=-t:y=0.5*(ih-iw/2.4)-t:w=iw+t*2:h=iw/2.4+t*2:t=2:c=red

   drawgrid
       Draw a grid on the input image.

       It accepts the following parameters:

       x
       y   The expressions which specify the coordinates of some point of grid
	   intersection (meant to configure offset). Both default to 0.

       width, w
       height, h
	   The expressions which specify the width and height of the grid
	   cell, if 0 they are interpreted as the input width and height,
	   respectively, minus "thickness", so image gets framed. Default to
	   0.

       color, c
	   Specify the color of the grid. For the general syntax of this
	   option, check the "Color" section in the ffmpeg-utils manual. If
	   the special value "invert" is used, the grid color is the same as
	   the video with inverted luma.

       thickness, t
	   The expression which sets the thickness of the grid line. Default
	   value is 1.

	   See below for the list of accepted constants.

       replace
	   Applicable if the input has alpha. With 1 the pixels of the painted
	   grid will overwrite the video's color and alpha pixels.  Default is
	   0, which composites the grid onto the input, leaving the video's
	   alpha intact.

       The parameters for x, y, w and h and t are expressions containing the
       following constants:

       dar The input display aspect ratio, it is the same as (w / h) * sar.

       hsub
       vsub
	   horizontal and vertical chroma subsample values. For example for
	   the pixel format "yuv422p" hsub is 2 and vsub is 1.

       in_h, ih
       in_w, iw
	   The input grid cell width and height.

       sar The input sample aspect ratio.

       x
       y   The x and y coordinates of some point of grid intersection (meant
	   to configure offset).

       w
       h   The width and height of the drawn cell.

       t   The thickness of the drawn cell.

	   These constants allow the x, y, w, h and t expressions to refer to
	   each other, so you may for example specify "y=x/dar" or "h=w/dar".

       Examples

       ·   Draw a grid with cell 100x100 pixels, thickness 2 pixels, with
	   color red and an opacity of 50%:

		   drawgrid=width=100:height=100:thickness=2:color=red@0.5

       ·   Draw a white 3x3 grid with an opacity of 50%:

		   drawgrid=w=iw/3:h=ih/3:t=2:c=white@0.5

   drawtext
       Draw a text string or text from a specified file on top of a video,
       using the libfreetype library.

       To enable compilation of this filter, you need to configure FFmpeg with
       "--enable-libfreetype".	To enable default font fallback and the font
       option you need to configure FFmpeg with "--enable-libfontconfig".  To
       enable the text_shaping option, you need to configure FFmpeg with
       "--enable-libfribidi".

       Syntax

       It accepts the following parameters:

       box Used to draw a box around text using the background color.  The
	   value must be either 1 (enable) or 0 (disable).  The default value
	   of box is 0.

       boxborderw
	   Set the width of the border to be drawn around the box using
	   boxcolor.  The default value of boxborderw is 0.

       boxcolor
	   The color to be used for drawing box around text. For the syntax of
	   this option, check the "Color" section in the ffmpeg-utils manual.

	   The default value of boxcolor is "white".

       line_spacing
	   Set the line spacing in pixels of the border to be drawn around the
	   box using box.  The default value of line_spacing is 0.

       borderw
	   Set the width of the border to be drawn around the text using
	   bordercolor.  The default value of borderw is 0.

       bordercolor
	   Set the color to be used for drawing border around text. For the
	   syntax of this option, check the "Color" section in the ffmpeg-
	   utils manual.

	   The default value of bordercolor is "black".

       expansion
	   Select how the text is expanded. Can be either "none", "strftime"
	   (deprecated) or "normal" (default). See the drawtext_expansion,
	   Text expansion section below for details.

       basetime
	   Set a start time for the count. Value is in microseconds. Only
	   applied in the deprecated strftime expansion mode. To emulate in
	   normal expansion mode use the "pts" function, supplying the start
	   time (in seconds) as the second argument.

       fix_bounds
	   If true, check and fix text coords to avoid clipping.

       fontcolor
	   The color to be used for drawing fonts. For the syntax of this
	   option, check the "Color" section in the ffmpeg-utils manual.

	   The default value of fontcolor is "black".

       fontcolor_expr
	   String which is expanded the same way as text to obtain dynamic
	   fontcolor value. By default this option has empty value and is not
	   processed. When this option is set, it overrides fontcolor option.

       font
	   The font family to be used for drawing text. By default Sans.

       fontfile
	   The font file to be used for drawing text. The path must be
	   included.  This parameter is mandatory if the fontconfig support is
	   disabled.

       alpha
	   Draw the text applying alpha blending. The value can be a number
	   between 0.0 and 1.0.  The expression accepts the same variables x,
	   y as well.  The default value is 1.	Please see fontcolor_expr.

       fontsize
	   The font size to be used for drawing text.  The default value of
	   fontsize is 16.

       text_shaping
	   If set to 1, attempt to shape the text (for example, reverse the
	   order of right-to-left text and join Arabic characters) before
	   drawing it.	Otherwise, just draw the text exactly as given.  By
	   default 1 (if supported).

       ft_load_flags
	   The flags to be used for loading the fonts.

	   The flags map the corresponding flags supported by libfreetype, and
	   are a combination of the following values:

	   default
	   no_scale
	   no_hinting
	   render
	   no_bitmap
	   vertical_layout
	   force_autohint
	   crop_bitmap
	   pedantic
	   ignore_global_advance_width
	   no_recurse
	   ignore_transform
	   monochrome
	   linear_design
	   no_autohint

	   Default value is "default".

	   For more information consult the documentation for the FT_LOAD_*
	   libfreetype flags.

       shadowcolor
	   The color to be used for drawing a shadow behind the drawn text.
	   For the syntax of this option, check the "Color" section in the
	   ffmpeg-utils manual.

	   The default value of shadowcolor is "black".

       shadowx
       shadowy
	   The x and y offsets for the text shadow position with respect to
	   the position of the text. They can be either positive or negative
	   values. The default value for both is "0".

       start_number
	   The starting frame number for the n/frame_num variable. The default
	   value is "0".

       tabsize
	   The size in number of spaces to use for rendering the tab.  Default
	   value is 4.

       timecode
	   Set the initial timecode representation in "hh:mm:ss[:;.]ff"
	   format. It can be used with or without text parameter.
	   timecode_rate option must be specified.

       timecode_rate, rate, r
	   Set the timecode frame rate (timecode only). Value will be rounded
	   to nearest integer. Minimum value is "1".  Drop-frame timecode is
	   supported for frame rates 30 & 60.

       tc24hmax
	   If set to 1, the output of the timecode option will wrap around at
	   24 hours.  Default is 0 (disabled).

       text
	   The text string to be drawn. The text must be a sequence of UTF-8
	   encoded characters.	This parameter is mandatory if no file is
	   specified with the parameter textfile.

       textfile
	   A text file containing text to be drawn. The text must be a
	   sequence of UTF-8 encoded characters.

	   This parameter is mandatory if no text string is specified with the
	   parameter text.

	   If both text and textfile are specified, an error is thrown.

       reload
	   If set to 1, the textfile will be reloaded before each frame.  Be
	   sure to update it atomically, or it may be read partially, or even
	   fail.

       x
       y   The expressions which specify the offsets where text will be drawn
	   within the video frame. They are relative to the top/left border of
	   the output image.

	   The default value of x and y is "0".

	   See below for the list of accepted constants and functions.

       The parameters for x and y are expressions containing the following
       constants and functions:

       dar input display aspect ratio, it is the same as (w / h) * sar

       hsub
       vsub
	   horizontal and vertical chroma subsample values. For example for
	   the pixel format "yuv422p" hsub is 2 and vsub is 1.

       line_h, lh
	   the height of each text line

       main_h, h, H
	   the input height

       main_w, w, W
	   the input width

       max_glyph_a, ascent
	   the maximum distance from the baseline to the highest/upper grid
	   coordinate used to place a glyph outline point, for all the
	   rendered glyphs.  It is a positive value, due to the grid's
	   orientation with the Y axis upwards.

       max_glyph_d, descent
	   the maximum distance from the baseline to the lowest grid
	   coordinate used to place a glyph outline point, for all the
	   rendered glyphs.  This is a negative value, due to the grid's
	   orientation, with the Y axis upwards.

       max_glyph_h
	   maximum glyph height, that is the maximum height for all the glyphs
	   contained in the rendered text, it is equivalent to ascent -
	   descent.

       max_glyph_w
	   maximum glyph width, that is the maximum width for all the glyphs
	   contained in the rendered text

       n   the number of input frame, starting from 0

       rand(min, max)
	   return a random number included between min and max

       sar The input sample aspect ratio.

       t   timestamp expressed in seconds, NAN if the input timestamp is
	   unknown

       text_h, th
	   the height of the rendered text

       text_w, tw
	   the width of the rendered text

       x
       y   the x and y offset coordinates where the text is drawn.

	   These parameters allow the x and y expressions to refer each other,
	   so you can for example specify "y=x/dar".

       Text expansion

       If expansion is set to "strftime", the filter recognizes strftime()
       sequences in the provided text and expands them accordingly. Check the
       documentation of strftime(). This feature is deprecated.

       If expansion is set to "none", the text is printed verbatim.

       If expansion is set to "normal" (which is the default), the following
       expansion mechanism is used.

       The backslash character \, followed by any character, always expands to
       the second character.

       Sequences of the form "%{...}" are expanded. The text between the
       braces is a function name, possibly followed by arguments separated by
       ':'.  If the arguments contain special characters or delimiters (':' or
       '}'), they should be escaped.

       Note that they probably must also be escaped as the value for the text
       option in the filter argument string and as the filter argument in the
       filtergraph description, and possibly also for the shell, that makes up
       to four levels of escaping; using a text file avoids these problems.

       The following functions are available:

       expr, e
	   The expression evaluation result.

	   It must take one argument specifying the expression to be
	   evaluated, which accepts the same constants and functions as the x
	   and y values. Note that not all constants should be used, for
	   example the text size is not known when evaluating the expression,
	   so the constants text_w and text_h will have an undefined value.

       expr_int_format, eif
	   Evaluate the expression's value and output as formatted integer.

	   The first argument is the expression to be evaluated, just as for
	   the expr function.  The second argument specifies the output
	   format. Allowed values are x, X, d and u. They are treated exactly
	   as in the "printf" function.  The third parameter is optional and
	   sets the number of positions taken by the output.  It can be used
	   to add padding with zeros from the left.

       gmtime
	   The time at which the filter is running, expressed in UTC.  It can
	   accept an argument: a strftime() format string.

       localtime
	   The time at which the filter is running, expressed in the local
	   time zone.  It can accept an argument: a strftime() format string.

       metadata
	   Frame metadata. Takes one or two arguments.

	   The first argument is mandatory and specifies the metadata key.

	   The second argument is optional and specifies a default value, used
	   when the metadata key is not found or empty.

       n, frame_num
	   The frame number, starting from 0.

       pict_type
	   A 1 character description of the current picture type.

       pts The timestamp of the current frame.	It can take up to three
	   arguments.

	   The first argument is the format of the timestamp; it defaults to
	   "flt" for seconds as a decimal number with microsecond accuracy;
	   "hms" stands for a formatted [-]HH:MM:SS.mmm timestamp with
	   millisecond accuracy.  "gmtime" stands for the timestamp of the
	   frame formatted as UTC time; "localtime" stands for the timestamp
	   of the frame formatted as local time zone time.

	   The second argument is an offset added to the timestamp.

	   If the format is set to "hms", a third argument "24HH" may be
	   supplied to present the hour part of the formatted timestamp in 24h
	   format (00-23).

	   If the format is set to "localtime" or "gmtime", a third argument
	   may be supplied: a strftime() format string.  By default, YYYY-MM-
	   DD HH:MM:SS format will be used.

       Examples

       ·   Draw "Test Text" with font FreeSerif, using the default values for
	   the optional parameters.

		   drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"

       ·   Draw 'Test Text' with font FreeSerif of size 24 at position x=100
	   and y=50 (counting from the top-left corner of the screen), text is
	   yellow with a red box around it. Both the text and the box have an
	   opacity of 20%.

		   drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
			     x=100: y=50: fontsize=24: fontcolor=yellow@0.2: box=1: boxcolor=red@0.2"

	   Note that the double quotes are not necessary if spaces are not
	   used within the parameter list.

       ·   Show the text at the center of the video frame:

		   drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h)/2"

       ·   Show the text at a random position, switching to a new position
	   every 30 seconds:

		   drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=if(eq(mod(t\,30)\,0)\,rand(0\,(w-text_w))\,x):y=if(eq(mod(t\,30)\,0)\,rand(0\,(h-text_h))\,y)"

       ·   Show a text line sliding from right to left in the last row of the
	   video frame. The file LONG_LINE is assumed to contain a single line
	   with no newlines.

		   drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"

       ·   Show the content of file CREDITS off the bottom of the frame and
	   scroll up.

		   drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"

       ·   Draw a single green letter "g", at the center of the input video.
	   The glyph baseline is placed at half screen height.

		   drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"

       ·   Show text for 1 second every 3 seconds:

		   drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"

       ·   Use fontconfig to set the font. Note that the colons need to be
	   escaped.

		   drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'

       ·   Print the date of a real-time encoding (see strftime(3)):

		   drawtext='fontfile=FreeSans.ttf:text=%{localtime\:%a %b %d %Y}'

       ·   Show text fading in and out (appearing/disappearing):

		   #!/bin/sh
		   DS=1.0 # display start
		   DE=10.0 # display end
		   FID=1.5 # fade in duration
		   FOD=5 # fade out duration
		   ffplay -f lavfi "color,drawtext=text=TEST:fontsize=50:fontfile=FreeSerif.ttf:fontcolor_expr=ff0000%{eif\\\\: clip(255*(1*between(t\\, $DS + $FID\\, $DE - $FOD) + ((t - $DS)/$FID)*between(t\\, $DS\\, $DS + $FID) + (-(t - $DE)/$FOD)*between(t\\, $DE - $FOD\\, $DE) )\\, 0\\, 255) \\\\: x\\\\: 2 }"

       ·   Horizontally align multiple separate texts. Note that max_glyph_a
	   and the fontsize value are included in the y offset.

		   drawtext=fontfile=FreeSans.ttf:text=DOG:fontsize=24:x=10:y=20+24-max_glyph_a,
		   drawtext=fontfile=FreeSans.ttf:text=cow:fontsize=24:x=80:y=20+24-max_glyph_a

       For more information about libfreetype, check:
       <http://www.freetype.org/>.

       For more information about fontconfig, check:
       <http://freedesktop.org/software/fontconfig/fontconfig-user.html>.

       For more information about libfribidi, check: <http://fribidi.org/>.

   edgedetect
       Detect and draw edges. The filter uses the Canny Edge Detection
       algorithm.

       The filter accepts the following options:

       low
       high
	   Set low and high threshold values used by the Canny thresholding
	   algorithm.

	   The high threshold selects the "strong" edge pixels, which are then
	   connected through 8-connectivity with the "weak" edge pixels
	   selected by the low threshold.

	   low and high threshold values must be chosen in the range [0,1],
	   and low should be lesser or equal to high.

	   Default value for low is "20/255", and default value for high is
	   "50/255".

       mode
	   Define the drawing mode.

	   wires
	       Draw white/gray wires on black background.

	   colormix
	       Mix the colors to create a paint/cartoon effect.

	   canny
	       Apply Canny edge detector on all selected planes.

	   Default value is wires.

       planes
	   Select planes for filtering. By default all available planes are
	   filtered.

       Examples

       ·   Standard edge detection with custom values for the hysteresis
	   thresholding:

		   edgedetect=low=0.1:high=0.4

       ·   Painting effect without thresholding:

		   edgedetect=mode=colormix:high=0

   eq
       Set brightness, contrast, saturation and approximate gamma adjustment.

       The filter accepts the following options:

       contrast
	   Set the contrast expression. The value must be a float value in
	   range "-2.0" to 2.0. The default value is "1".

       brightness
	   Set the brightness expression. The value must be a float value in
	   range "-1.0" to 1.0. The default value is "0".

       saturation
	   Set the saturation expression. The value must be a float in range
	   0.0 to 3.0. The default value is "1".

       gamma
	   Set the gamma expression. The value must be a float in range 0.1 to
	   10.0.  The default value is "1".

       gamma_r
	   Set the gamma expression for red. The value must be a float in
	   range 0.1 to 10.0. The default value is "1".

       gamma_g
	   Set the gamma expression for green. The value must be a float in
	   range 0.1 to 10.0. The default value is "1".

       gamma_b
	   Set the gamma expression for blue. The value must be a float in
	   range 0.1 to 10.0. The default value is "1".

       gamma_weight
	   Set the gamma weight expression. It can be used to reduce the
	   effect of a high gamma value on bright image areas, e.g. keep them
	   from getting overamplified and just plain white. The value must be
	   a float in range 0.0 to 1.0. A value of 0.0 turns the gamma
	   correction all the way down while 1.0 leaves it at its full
	   strength. Default is "1".

       eval
	   Set when the expressions for brightness, contrast, saturation and
	   gamma expressions are evaluated.

	   It accepts the following values:

	   init
	       only evaluate expressions once during the filter initialization
	       or when a command is processed

	   frame
	       evaluate expressions for each incoming frame

	   Default value is init.

       The expressions accept the following parameters:

       n   frame count of the input frame starting from 0

       pos byte position of the corresponding packet in the input file, NAN if
	   unspecified

       r   frame rate of the input video, NAN if the input frame rate is
	   unknown

       t   timestamp expressed in seconds, NAN if the input timestamp is
	   unknown

       Commands

       The filter supports the following commands:

       contrast
	   Set the contrast expression.

       brightness
	   Set the brightness expression.

       saturation
	   Set the saturation expression.

       gamma
	   Set the gamma expression.

       gamma_r
	   Set the gamma_r expression.

       gamma_g
	   Set gamma_g expression.

       gamma_b
	   Set gamma_b expression.

       gamma_weight
	   Set gamma_weight expression.

	   The command accepts the same syntax of the corresponding option.

	   If the specified expression is not valid, it is kept at its current
	   value.

   erosion
       Apply erosion effect to the video.

       This filter replaces the pixel by the local(3x3) minimum.

       It accepts the following options:

       threshold0
       threshold1
       threshold2
       threshold3
	   Limit the maximum change for each plane, default is 65535.  If 0,
	   plane will remain unchanged.

       coordinates
	   Flag which specifies the pixel to refer to. Default is 255 i.e. all
	   eight pixels are used.

	   Flags to local 3x3 coordinates maps like this:

	       1 2 3
	       4   5
	       6 7 8

   extractplanes
       Extract color channel components from input video stream into separate
       grayscale video streams.

       The filter accepts the following option:

       planes
	   Set plane(s) to extract.

	   Available values for planes are:

	   y
	   u
	   v
	   a
	   r
	   g
	   b

	   Choosing planes not available in the input will result in an error.
	   That means you cannot select "r", "g", "b" planes with "y", "u",
	   "v" planes at same time.

       Examples

       ·   Extract luma, u and v color channel component from input video
	   frame into 3 grayscale outputs:

		   ffmpeg -i video.avi -filter_complex 'extractplanes=y+u+v[y][u][v]' -map '[y]' y.avi -map '[u]' u.avi -map '[v]' v.avi

   elbg
       Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.

       For each input image, the filter will compute the optimal mapping from
       the input to the output given the codebook length, that is the number
       of distinct output colors.

       This filter accepts the following options.

       codebook_length, l
	   Set codebook length. The value must be a positive integer, and
	   represents the number of distinct output colors. Default value is
	   256.

       nb_steps, n
	   Set the maximum number of iterations to apply for computing the
	   optimal mapping. The higher the value the better the result and the
	   higher the computation time. Default value is 1.

       seed, s
	   Set a random seed, must be an integer included between 0 and
	   UINT32_MAX. If not specified, or if explicitly set to -1, the
	   filter will try to use a good random seed on a best effort basis.

       pal8
	   Set pal8 output pixel format. This option does not work with
	   codebook length greater than 256.

   entropy
       Measure graylevel entropy in histogram of color channels of video
       frames.

       It accepts the following parameters:

       mode
	   Can be either normal or diff. Default is normal.

	   diff mode measures entropy of histogram delta values, absolute
	   differences between neighbour histogram values.

   fade
       Apply a fade-in/out effect to the input video.

       It accepts the following parameters:

       type, t
	   The effect type can be either "in" for a fade-in, or "out" for a
	   fade-out effect.  Default is "in".

       start_frame, s
	   Specify the number of the frame to start applying the fade effect
	   at. Default is 0.

       nb_frames, n
	   The number of frames that the fade effect lasts. At the end of the
	   fade-in effect, the output video will have the same intensity as
	   the input video.  At the end of the fade-out transition, the output
	   video will be filled with the selected color.  Default is 25.

       alpha
	   If set to 1, fade only alpha channel, if one exists on the input.
	   Default value is 0.

       start_time, st
	   Specify the timestamp (in seconds) of the frame to start to apply
	   the fade effect. If both start_frame and start_time are specified,
	   the fade will start at whichever comes last.  Default is 0.

       duration, d
	   The number of seconds for which the fade effect has to last. At the
	   end of the fade-in effect the output video will have the same
	   intensity as the input video, at the end of the fade-out transition
	   the output video will be filled with the selected color.  If both
	   duration and nb_frames are specified, duration is used. Default is
	   0 (nb_frames is used by default).

       color, c
	   Specify the color of the fade. Default is "black".

       Examples

       ·   Fade in the first 30 frames of video:

		   fade=in:0:30

	   The command above is equivalent to:

		   fade=t=in:s=0:n=30

       ·   Fade out the last 45 frames of a 200-frame video:

		   fade=out:155:45
		   fade=type=out:start_frame=155:nb_frames=45

       ·   Fade in the first 25 frames and fade out the last 25 frames of a
	   1000-frame video:

		   fade=in:0:25, fade=out:975:25

       ·   Make the first 5 frames yellow, then fade in from frame 5-24:

		   fade=in:5:20:color=yellow

       ·   Fade in alpha over first 25 frames of video:

		   fade=in:0:25:alpha=1

       ·   Make the first 5.5 seconds black, then fade in for 0.5 seconds:

		   fade=t=in:st=5.5:d=0.5

   fftfilt
       Apply arbitrary expressions to samples in frequency domain

       dc_Y
	   Adjust the dc value (gain) of the luma plane of the image. The
	   filter accepts an integer value in range 0 to 1000. The default
	   value is set to 0.

       dc_U
	   Adjust the dc value (gain) of the 1st chroma plane of the image.
	   The filter accepts an integer value in range 0 to 1000. The default
	   value is set to 0.

       dc_V
	   Adjust the dc value (gain) of the 2nd chroma plane of the image.
	   The filter accepts an integer value in range 0 to 1000. The default
	   value is set to 0.

       weight_Y
	   Set the frequency domain weight expression for the luma plane.

       weight_U
	   Set the frequency domain weight expression for the 1st chroma
	   plane.

       weight_V
	   Set the frequency domain weight expression for the 2nd chroma
	   plane.

       eval
	   Set when the expressions are evaluated.

	   It accepts the following values:

	   init
	       Only evaluate expressions once during the filter
	       initialization.

	   frame
	       Evaluate expressions for each incoming frame.

	   Default value is init.

	   The filter accepts the following variables:

       X
       Y   The coordinates of the current sample.

       W
       H   The width and height of the image.

       N   The number of input frame, starting from 0.

       Examples

       ·   High-pass:

		   fftfilt=dc_Y=128:weight_Y='squish(1-(Y+X)/100)'

       ·   Low-pass:

		   fftfilt=dc_Y=0:weight_Y='squish((Y+X)/100-1)'

       ·   Sharpen:

		   fftfilt=dc_Y=0:weight_Y='1+squish(1-(Y+X)/100)'

       ·   Blur:

		   fftfilt=dc_Y=0:weight_Y='exp(-4 * ((Y+X)/(W+H)))'

   fftdnoiz
       Denoise frames using 3D FFT (frequency domain filtering).

       The filter accepts the following options:

       sigma
	   Set the noise sigma constant. This sets denoising strength.
	   Default value is 1. Allowed range is from 0 to 30.  Using very high
	   sigma with low overlap may give blocking artifacts.

       amount
	   Set amount of denoising. By default all detected noise is reduced.
	   Default value is 1. Allowed range is from 0 to 1.

       block
	   Set size of block, Default is 4, can be 3, 4, 5 or 6.  Actual size
	   of block in pixels is 2 to power of block, so by default block size
	   in pixels is 2^4 which is 16.

       overlap
	   Set block overlap. Default is 0.5. Allowed range is from 0.2 to
	   0.8.

       prev
	   Set number of previous frames to use for denoising. By default is
	   set to 0.

       next
	   Set number of next frames to to use for denoising. By default is
	   set to 0.

       planes
	   Set planes which will be filtered, by default are all available
	   filtered except alpha.

   field
       Extract a single field from an interlaced image using stride arithmetic
       to avoid wasting CPU time. The output frames are marked as non-
       interlaced.

       The filter accepts the following options:

       type
	   Specify whether to extract the top (if the value is 0 or "top") or
	   the bottom field (if the value is 1 or "bottom").

   fieldhint
       Create new frames by copying the top and bottom fields from surrounding
       frames supplied as numbers by the hint file.

       hint
	   Set file containing hints: absolute/relative frame numbers.

	   There must be one line for each frame in a clip. Each line must
	   contain two numbers separated by the comma, optionally followed by
	   "-" or "+".	Numbers supplied on each line of file can not be out
	   of [N-1,N+1] where N is current frame number for "absolute" mode or
	   out of [-1, 1] range for "relative" mode. First number tells from
	   which frame to pick up top field and second number tells from which
	   frame to pick up bottom field.

	   If optionally followed by "+" output frame will be marked as
	   interlaced, else if followed by "-" output frame will be marked as
	   progressive, else it will be marked same as input frame.  If line
	   starts with "#" or ";" that line is skipped.

       mode
	   Can be item "absolute" or "relative". Default is "absolute".

       Example of first several lines of "hint" file for "relative" mode:

	       0,0 - # first frame
	       1,0 - # second frame, use third's frame top field and second's frame bottom field
	       1,0 - # third frame, use fourth's frame top field and third's frame bottom field
	       1,0 -
	       0,0 -
	       0,0 -
	       1,0 -
	       1,0 -
	       1,0 -
	       0,0 -
	       0,0 -
	       1,0 -
	       1,0 -
	       1,0 -
	       0,0 -

   fieldmatch
       Field matching filter for inverse telecine. It is meant to reconstruct
       the progressive frames from a telecined stream. The filter does not
       drop duplicated frames, so to achieve a complete inverse telecine
       "fieldmatch" needs to be followed by a decimation filter such as
       decimate in the filtergraph.

       The separation of the field matching and the decimation is notably
       motivated by the possibility of inserting a de-interlacing filter
       fallback between the two.  If the source has mixed telecined and real
       interlaced content, "fieldmatch" will not be able to match fields for
       the interlaced parts.  But these remaining combed frames will be marked
       as interlaced, and thus can be de-interlaced by a later filter such as
       yadif before decimation.

       In addition to the various configuration options, "fieldmatch" can take
       an optional second stream, activated through the ppsrc option. If
       enabled, the frames reconstruction will be based on the fields and
       frames from this second stream. This allows the first input to be pre-
       processed in order to help the various algorithms of the filter, while
       keeping the output lossless (assuming the fields are matched properly).
       Typically, a field-aware denoiser, or brightness/contrast adjustments
       can help.

       Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth
       project) and VIVTC/VFM (VapourSynth project). The later is a light
       clone of TFM from which "fieldmatch" is based on. While the semantic
       and usage are very close, some behaviour and options names can differ.

       The decimate filter currently only works for constant frame rate input.
       If your input has mixed telecined (30fps) and progressive content with
       a lower framerate like 24fps use the following filterchain to produce
       the necessary cfr stream:
       "dejudder,fps=30000/1001,fieldmatch,decimate".

       The filter accepts the following options:

       order
	   Specify the assumed field order of the input stream. Available
	   values are:

	   auto
	       Auto detect parity (use FFmpeg's internal parity value).

	   bff Assume bottom field first.

	   tff Assume top field first.

	   Note that it is sometimes recommended not to trust the parity
	   announced by the stream.

	   Default value is auto.

       mode
	   Set the matching mode or strategy to use. pc mode is the safest in
	   the sense that it won't risk creating jerkiness due to duplicate
	   frames when possible, but if there are bad edits or blended fields
	   it will end up outputting combed frames when a good match might
	   actually exist. On the other hand, pcn_ub mode is the most risky in
	   terms of creating jerkiness, but will almost always find a good
	   frame if there is one. The other values are all somewhere in
	   between pc and pcn_ub in terms of risking jerkiness and creating
	   duplicate frames versus finding good matches in sections with bad
	   edits, orphaned fields, blended fields, etc.

	   More details about p/c/n/u/b are available in p/c/n/u/b meaning
	   section.

	   Available values are:

	   pc  2-way matching (p/c)

	   pc_n
	       2-way matching, and trying 3rd match if still combed (p/c + n)

	   pc_u
	       2-way matching, and trying 3rd match (same order) if still
	       combed (p/c + u)

	   pc_n_ub
	       2-way matching, trying 3rd match if still combed, and trying
	       4th/5th matches if still combed (p/c + n + u/b)

	   pcn 3-way matching (p/c/n)

	   pcn_ub
	       3-way matching, and trying 4th/5th matches if all 3 of the
	       original matches are detected as combed (p/c/n + u/b)

	   The parenthesis at the end indicate the matches that would be used
	   for that mode assuming order=tff (and field on auto or top).

	   In terms of speed pc mode is by far the fastest and pcn_ub is the
	   slowest.

	   Default value is pc_n.

       ppsrc
	   Mark the main input stream as a pre-processed input, and enable the
	   secondary input stream as the clean source to pick the fields from.
	   See the filter introduction for more details. It is similar to the
	   clip2 feature from VFM/TFM.

	   Default value is 0 (disabled).

       field
	   Set the field to match from. It is recommended to set this to the
	   same value as order unless you experience matching failures with
	   that setting. In certain circumstances changing the field that is
	   used to match from can have a large impact on matching performance.
	   Available values are:

	   auto
	       Automatic (same value as order).

	   bottom
	       Match from the bottom field.

	   top Match from the top field.

	   Default value is auto.

       mchroma
	   Set whether or not chroma is included during the match comparisons.
	   In most cases it is recommended to leave this enabled. You should
	   set this to 0 only if your clip has bad chroma problems such as
	   heavy rainbowing or other artifacts. Setting this to 0 could also
	   be used to speed things up at the cost of some accuracy.

	   Default value is 1.

       y0
       y1  These define an exclusion band which excludes the lines between y0
	   and y1 from being included in the field matching decision. An
	   exclusion band can be used to ignore subtitles, a logo, or other
	   things that may interfere with the matching. y0 sets the starting
	   scan line and y1 sets the ending line; all lines in between y0 and
	   y1 (including y0 and y1) will be ignored. Setting y0 and y1 to the
	   same value will disable the feature.  y0 and y1 defaults to 0.

       scthresh
	   Set the scene change detection threshold as a percentage of maximum
	   change on the luma plane. Good values are in the "[8.0, 14.0]"
	   range. Scene change detection is only relevant in case
	   combmatch=sc.  The range for scthresh is "[0.0, 100.0]".

	   Default value is 12.0.

       combmatch
	   When combatch is not none, "fieldmatch" will take into account the
	   combed scores of matches when deciding what match to use as the
	   final match. Available values are:

	   none
	       No final matching based on combed scores.

	   sc  Combed scores are only used when a scene change is detected.

	   full
	       Use combed scores all the time.

	   Default is sc.

       combdbg
	   Force "fieldmatch" to calculate the combed metrics for certain
	   matches and print them. This setting is known as micout in TFM/VFM
	   vocabulary.	Available values are:

	   none
	       No forced calculation.

	   pcn Force p/c/n calculations.

	   pcnub
	       Force p/c/n/u/b calculations.

	   Default value is none.

       cthresh
	   This is the area combing threshold used for combed frame detection.
	   This essentially controls how "strong" or "visible" combing must be
	   to be detected.  Larger values mean combing must be more visible
	   and smaller values mean combing can be less visible or strong and
	   still be detected. Valid settings are from "-1" (every pixel will
	   be detected as combed) to 255 (no pixel will be detected as
	   combed). This is basically a pixel difference value. A good range
	   is "[8, 12]".

	   Default value is 9.

       chroma
	   Sets whether or not chroma is considered in the combed frame
	   decision.  Only disable this if your source has chroma problems
	   (rainbowing, etc.) that are causing problems for the combed frame
	   detection with chroma enabled. Actually, using chroma=0 is usually
	   more reliable, except for the case where there is chroma only
	   combing in the source.

	   Default value is 0.

       blockx
       blocky
	   Respectively set the x-axis and y-axis size of the window used
	   during combed frame detection. This has to do with the size of the
	   area in which combpel pixels are required to be detected as combed
	   for a frame to be declared combed. See the combpel parameter
	   description for more info.  Possible values are any number that is
	   a power of 2 starting at 4 and going up to 512.

	   Default value is 16.

       combpel
	   The number of combed pixels inside any of the blocky by blockx size
	   blocks on the frame for the frame to be detected as combed. While
	   cthresh controls how "visible" the combing must be, this setting
	   controls "how much" combing there must be in any localized area (a
	   window defined by the blockx and blocky settings) on the frame.
	   Minimum value is 0 and maximum is "blocky x blockx" (at which point
	   no frames will ever be detected as combed). This setting is known
	   as MI in TFM/VFM vocabulary.

	   Default value is 80.

       p/c/n/u/b meaning

       p/c/n

       We assume the following telecined stream:

	       Top fields:     1 2 2 3 4
	       Bottom fields:  1 2 3 4 4

       The numbers correspond to the progressive frame the fields relate to.
       Here, the first two frames are progressive, the 3rd and 4th are combed,
       and so on.

       When "fieldmatch" is configured to run a matching from bottom
       (field=bottom) this is how this input stream get transformed:

	       Input stream:
			       T     1 2 2 3 4
			       B     1 2 3 4 4	 <-- matching reference

	       Matches: 	     c c n n c

	       Output stream:
			       T     1 2 3 4 4
			       B     1 2 3 4 4

       As a result of the field matching, we can see that some frames get
       duplicated.  To perform a complete inverse telecine, you need to rely
       on a decimation filter after this operation. See for instance the
       decimate filter.

       The same operation now matching from top fields (field=top) looks like
       this:

	       Input stream:
			       T     1 2 2 3 4	 <-- matching reference
			       B     1 2 3 4 4

	       Matches: 	     c c p p c

	       Output stream:
			       T     1 2 2 3 4
			       B     1 2 2 3 4

       In these examples, we can see what p, c and n mean; basically, they
       refer to the frame and field of the opposite parity:

       *<p matches the field of the opposite parity in the previous frame>
       *<c matches the field of the opposite parity in the current frame>
       *<n matches the field of the opposite parity in the next frame>

       u/b

       The u and b matching are a bit special in the sense that they match
       from the opposite parity flag. In the following examples, we assume
       that we are currently matching the 2nd frame (Top:2, bottom:2).
       According to the match, a 'x' is placed above and below each matched
       fields.

       With bottom matching (field=bottom):

	       Match:		c	  p	      n 	 b	    u

				x	x		x	 x	    x
		 Top	      1 2 2	1 2 2	    1 2 2      1 2 2	  1 2 2
		 Bottom       1 2 3	1 2 3	    1 2 3      1 2 3	  1 2 3
				x	  x	      x        x	      x

	       Output frames:
				2	   1	      2 	 2	    2
				2	   2	      2 	 1	    3

       With top matching (field=top):

	       Match:		c	  p	      n 	 b	    u

				x	  x	      x        x	      x
		 Top	      1 2 2	1 2 2	    1 2 2      1 2 2	  1 2 2
		 Bottom       1 2 3	1 2 3	    1 2 3      1 2 3	  1 2 3
				x	x		x	 x	    x

	       Output frames:
				2	   2	      2 	 1	    2
				2	   1	      3 	 2	    2

       Examples

       Simple IVTC of a top field first telecined stream:

	       fieldmatch=order=tff:combmatch=none, decimate

       Advanced IVTC, with fallback on yadif for still combed frames:

	       fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate

   fieldorder
       Transform the field order of the input video.

       It accepts the following parameters:

       order
	   The output field order. Valid values are tff for top field first or
	   bff for bottom field first.

       The default value is tff.

       The transformation is done by shifting the picture content up or down
       by one line, and filling the remaining line with appropriate picture
       content.  This method is consistent with most broadcast field order
       converters.

       If the input video is not flagged as being interlaced, or it is already
       flagged as being of the required output field order, then this filter
       does not alter the incoming video.

       It is very useful when converting to or from PAL DV material, which is
       bottom field first.

       For example:

	       ffmpeg -i in.vob -vf "fieldorder=bff" out.dv

   fifo, afifo
       Buffer input images and send them when they are requested.

       It is mainly useful when auto-inserted by the libavfilter framework.

       It does not take parameters.

   fillborders
       Fill borders of the input video, without changing video stream
       dimensions.  Sometimes video can have garbage at the four edges and you
       may not want to crop video input to keep size multiple of some number.

       This filter accepts the following options:

       left
	   Number of pixels to fill from left border.

       right
	   Number of pixels to fill from right border.

       top Number of pixels to fill from top border.

       bottom
	   Number of pixels to fill from bottom border.

       mode
	   Set fill mode.

	   It accepts the following values:

	   smear
	       fill pixels using outermost pixels

	   mirror
	       fill pixels using mirroring

	   fixed
	       fill pixels with constant value

	   Default is smear.

       color
	   Set color for pixels in fixed mode. Default is black.

   find_rect
       Find a rectangular object

       It accepts the following options:

       object
	   Filepath of the object image, needs to be in gray8.

       threshold
	   Detection threshold, default is 0.5.

       mipmaps
	   Number of mipmaps, default is 3.

       xmin, ymin, xmax, ymax
	   Specifies the rectangle in which to search.

       Examples

       ·   Generate a representative palette of a given video using ffmpeg:

		   ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv

   cover_rect
       Cover a rectangular object

       It accepts the following options:

       cover
	   Filepath of the optional cover image, needs to be in yuv420.

       mode
	   Set covering mode.

	   It accepts the following values:

	   cover
	       cover it by the supplied image

	   blur
	       cover it by interpolating the surrounding pixels

	   Default value is blur.

       Examples

       ·   Generate a representative palette of a given video using ffmpeg:

		   ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv

   floodfill
       Flood area with values of same pixel components with another values.

       It accepts the following options:

       x   Set pixel x coordinate.

       y   Set pixel y coordinate.

       s0  Set source #0 component value.

       s1  Set source #1 component value.

       s2  Set source #2 component value.

       s3  Set source #3 component value.

       d0  Set destination #0 component value.

       d1  Set destination #1 component value.

       d2  Set destination #2 component value.

       d3  Set destination #3 component value.

   format
       Convert the input video to one of the specified pixel formats.
       Libavfilter will try to pick one that is suitable as input to the next
       filter.

       It accepts the following parameters:

       pix_fmts
	   A '|'-separated list of pixel format names, such as
	   "pix_fmts=yuv420p|monow|rgb24".

       Examples

       ·   Convert the input video to the yuv420p format

		   format=pix_fmts=yuv420p

	   Convert the input video to any of the formats in the list

		   format=pix_fmts=yuv420p|yuv444p|yuv410p

   fps
       Convert the video to specified constant frame rate by duplicating or
       dropping frames as necessary.

       It accepts the following parameters:

       fps The desired output frame rate. The default is 25.

       start_time
	   Assume the first PTS should be the given value, in seconds. This
	   allows for padding/trimming at the start of stream. By default, no
	   assumption is made about the first frame's expected PTS, so no
	   padding or trimming is done.  For example, this could be set to 0
	   to pad the beginning with duplicates of the first frame if a video
	   stream starts after the audio stream or to trim any frames with a
	   negative PTS.

       round
	   Timestamp (PTS) rounding method.

	   Possible values are:

	   zero
	       round towards 0

	   inf round away from 0

	   down
	       round towards -infinity

	   up  round towards +infinity

	   near
	       round to nearest

	   The default is "near".

       eof_action
	   Action performed when reading the last frame.

	   Possible values are:

	   round
	       Use same timestamp rounding method as used for other frames.

	   pass
	       Pass through last frame if input duration has not been reached
	       yet.

	   The default is "round".

       Alternatively, the options can be specified as a flat string:
       fps[:start_time[:round]].

       See also the setpts filter.

       Examples

       ·   A typical usage in order to set the fps to 25:

		   fps=fps=25

       ·   Sets the fps to 24, using abbreviation and rounding method to round
	   to nearest:

		   fps=fps=film:round=near

   framepack
       Pack two different video streams into a stereoscopic video, setting
       proper metadata on supported codecs. The two views should have the same
       size and framerate and processing will stop when the shorter video
       ends. Please note that you may conveniently adjust view properties with
       the scale and fps filters.

       It accepts the following parameters:

       format
	   The desired packing format. Supported values are:

	   sbs The views are next to each other (default).

	   tab The views are on top of each other.

	   lines
	       The views are packed by line.

	   columns
	       The views are packed by column.

	   frameseq
	       The views are temporally interleaved.

       Some examples:

	       # Convert left and right views into a frame-sequential video
	       ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT

	       # Convert views into a side-by-side video with the same output resolution as the input
	       ffmpeg -i LEFT -i RIGHT -filter_complex [0:v]scale=w=iw/2[left],[1:v]scale=w=iw/2[right],[left][right]framepack=sbs OUTPUT

   framerate
       Change the frame rate by interpolating new video output frames from the
       source frames.

       This filter is not designed to function correctly with interlaced
       media. If you wish to change the frame rate of interlaced media then
       you are required to deinterlace before this filter and re-interlace
       after this filter.

       A description of the accepted options follows.

       fps Specify the output frames per second. This option can also be
	   specified as a value alone. The default is 50.

       interp_start
	   Specify the start of a range where the output frame will be created
	   as a linear interpolation of two frames. The range is [0-255], the
	   default is 15.

       interp_end
	   Specify the end of a range where the output frame will be created
	   as a linear interpolation of two frames. The range is [0-255], the
	   default is 240.

       scene
	   Specify the level at which a scene change is detected as a value
	   between 0 and 100 to indicate a new scene; a low value reflects a
	   low probability for the current frame to introduce a new scene,
	   while a higher value means the current frame is more likely to be
	   one.  The default is 8.2.

       flags
	   Specify flags influencing the filter process.

	   Available value for flags is:

	   scene_change_detect, scd
	       Enable scene change detection using the value of the option
	       scene.  This flag is enabled by default.

   framestep
       Select one frame every N-th frame.

       This filter accepts the following option:

       step
	   Select frame after every "step" frames.  Allowed values are
	   positive integers higher than 0. Default value is 1.

   frei0r
       Apply a frei0r effect to the input video.

       To enable the compilation of this filter, you need to install the
       frei0r header and configure FFmpeg with "--enable-frei0r".

       It accepts the following parameters:

       filter_name
	   The name of the frei0r effect to load. If the environment variable
	   FREI0R_PATH is defined, the frei0r effect is searched for in each
	   of the directories specified by the colon-separated list in
	   FREI0R_PATH.  Otherwise, the standard frei0r paths are searched, in
	   this order: HOME/.frei0r-1/lib/, /usr/local/lib/frei0r-1/,
	   /usr/lib/frei0r-1/.

       filter_params
	   A '|'-separated list of parameters to pass to the frei0r effect.

       A frei0r effect parameter can be a boolean (its value is either "y" or
       "n"), a double, a color (specified as R/G/B, where R, G, and B are
       floating point numbers between 0.0 and 1.0, inclusive) or a color
       description as specified in the "Color" section in the ffmpeg-utils
       manual, a position (specified as X/Y, where X and Y are floating point
       numbers) and/or a string.

       The number and types of parameters depend on the loaded effect. If an
       effect parameter is not specified, the default value is set.

       Examples

       ·   Apply the distort0r effect, setting the first two double
	   parameters:

		   frei0r=filter_name=distort0r:filter_params=0.5|0.01

       ·   Apply the colordistance effect, taking a color as the first
	   parameter:

		   frei0r=colordistance:0.2/0.3/0.4
		   frei0r=colordistance:violet
		   frei0r=colordistance:0x112233

       ·   Apply the perspective effect, specifying the top left and top right
	   image positions:

		   frei0r=perspective:0.2/0.2|0.8/0.2

       For more information, see <http://frei0r.dyne.org>

   fspp
       Apply fast and simple postprocessing. It is a faster version of spp.

       It splits (I)DCT into horizontal/vertical passes. Unlike the simple
       post- processing filter, one of them is performed once per block, not
       per pixel.  This allows for much higher speed.

       The filter accepts the following options:

       quality
	   Set quality. This option defines the number of levels for
	   averaging. It accepts an integer in the range 4-5. Default value is
	   4.

       qp  Force a constant quantization parameter. It accepts an integer in
	   range 0-63.	If not set, the filter will use the QP from the video
	   stream (if available).

       strength
	   Set filter strength. It accepts an integer in range -15 to 32.
	   Lower values mean more details but also more artifacts, while
	   higher values make the image smoother but also blurrier. Default
	   value is 0 X PSNR optimal.

       use_bframe_qp
	   Enable the use of the QP from the B-Frames if set to 1. Using this
	   option may cause flicker since the B-Frames have often larger QP.
	   Default is 0 (not enabled).

   gblur
       Apply Gaussian blur filter.

       The filter accepts the following options:

       sigma
	   Set horizontal sigma, standard deviation of Gaussian blur. Default
	   is 0.5.

       steps
	   Set number of steps for Gaussian approximation. Defauls is 1.

       planes
	   Set which planes to filter. By default all planes are filtered.

       sigmaV
	   Set vertical sigma, if negative it will be same as "sigma".
	   Default is "-1".

   geq
       The filter accepts the following options:

       lum_expr, lum
	   Set the luminance expression.

       cb_expr, cb
	   Set the chrominance blue expression.

       cr_expr, cr
	   Set the chrominance red expression.

       alpha_expr, a
	   Set the alpha expression.

       red_expr, r
	   Set the red expression.

       green_expr, g
	   Set the green expression.

       blue_expr, b
	   Set the blue expression.

       The colorspace is selected according to the specified options. If one
       of the lum_expr, cb_expr, or cr_expr options is specified, the filter
       will automatically select a YCbCr colorspace. If one of the red_expr,
       green_expr, or blue_expr options is specified, it will select an RGB
       colorspace.

       If one of the chrominance expression is not defined, it falls back on
       the other one. If no alpha expression is specified it will evaluate to
       opaque value.  If none of chrominance expressions are specified, they
       will evaluate to the luminance expression.

       The expressions can use the following variables and functions:

       N   The sequential number of the filtered frame, starting from 0.

       X
       Y   The coordinates of the current sample.

       W
       H   The width and height of the image.

       SW
       SH  Width and height scale depending on the currently filtered plane.
	   It is the ratio between the corresponding luma plane number of
	   pixels and the current plane ones. E.g. for YUV4:2:0 the values are
	   "1,1" for the luma plane, and "0.5,0.5" for chroma planes.

       T   Time of the current frame, expressed in seconds.

       p(x, y)
	   Return the value of the pixel at location (x,y) of the current
	   plane.

       lum(x, y)
	   Return the value of the pixel at location (x,y) of the luminance
	   plane.

       cb(x, y)
	   Return the value of the pixel at location (x,y) of the blue-
	   difference chroma plane. Return 0 if there is no such plane.

       cr(x, y)
	   Return the value of the pixel at location (x,y) of the red-
	   difference chroma plane. Return 0 if there is no such plane.

       r(x, y)
       g(x, y)
       b(x, y)
	   Return the value of the pixel at location (x,y) of the
	   red/green/blue component. Return 0 if there is no such component.

       alpha(x, y)
	   Return the value of the pixel at location (x,y) of the alpha plane.
	   Return 0 if there is no such plane.

       For functions, if x and y are outside the area, the value will be
       automatically clipped to the closer edge.

       Examples

       ·   Flip the image horizontally:

		   geq=p(W-X\,Y)

       ·   Generate a bidimensional sine wave, with angle "PI/3" and a
	   wavelength of 100 pixels:

		   geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128

       ·   Generate a fancy enigmatic moving light:

		   nullsrc=s=256x256,geq=random(1)/hypot(X-cos(N*0.07)*W/2-W/2\,Y-sin(N*0.09)*H/2-H/2)^2*1000000*sin(N*0.02):128:128

       ·   Generate a quick emboss effect:

		   format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'

       ·   Modify RGB components depending on pixel position:

		   geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'

       ·   Create a radial gradient that is the same size as the input (also
	   see the vignette filter):

		   geq=lum=255*gauss((X/W-0.5)*3)*gauss((Y/H-0.5)*3)/gauss(0)/gauss(0),format=gray

   gradfun
       Fix the banding artifacts that are sometimes introduced into nearly
       flat regions by truncation to 8-bit color depth.  Interpolate the
       gradients that should go where the bands are, and dither them.

       It is designed for playback only.  Do not use it prior to lossy
       compression, because compression tends to lose the dither and bring
       back the bands.

       It accepts the following parameters:

       strength
	   The maximum amount by which the filter will change any one pixel.
	   This is also the threshold for detecting nearly flat regions.
	   Acceptable values range from .51 to 64; the default value is 1.2.
	   Out-of-range values will be clipped to the valid range.

       radius
	   The neighborhood to fit the gradient to. A larger radius makes for
	   smoother gradients, but also prevents the filter from modifying the
	   pixels near detailed regions. Acceptable values are 8-32; the
	   default value is 16. Out-of-range values will be clipped to the
	   valid range.

       Alternatively, the options can be specified as a flat string:
       strength[:radius]

       Examples

       ·   Apply the filter with a 3.5 strength and radius of 8:

		   gradfun=3.5:8

       ·   Specify radius, omitting the strength (which will fall-back to the
	   default value):

		   gradfun=radius=8

   greyedge
       A color constancy variation filter which estimates scene illumination
       via grey edge algorithm and corrects the scene colors accordingly.

       See: <https://staff.science.uva.nl/th.gevers/pub/GeversTIP07.pdf>

       The filter accepts the following options:

       difford
	   The order of differentiation to be applied on the scene. Must be
	   chosen in the range [0,2] and default value is 1.

       minknorm
	   The Minkowski parameter to be used for calculating the Minkowski
	   distance. Must be chosen in the range [0,20] and default value is
	   1. Set to 0 for getting max value instead of calculating Minkowski
	   distance.

       sigma
	   The standard deviation of Gaussian blur to be applied on the scene.
	   Must be chosen in the range [0,1024.0] and default value = 1.
	   floor( sigma * break_off_sigma(3) ) can't be euqal to 0 if difford
	   is greater than 0.

       Examples

       ·   Grey Edge:

		   greyedge=difford=1:minknorm=5:sigma=2

       ·   Max Edge:

		   greyedge=difford=1:minknorm=0:sigma=2

   haldclut
       Apply a Hald CLUT to a video stream.

       First input is the video stream to process, and second one is the Hald
       CLUT.  The Hald CLUT input can be a simple picture or a complete video
       stream.

       The filter accepts the following options:

       shortest
	   Force termination when the shortest input terminates. Default is 0.

       repeatlast
	   Continue applying the last CLUT after the end of the stream. A
	   value of 0 disable the filter after the last frame of the CLUT is
	   reached.  Default is 1.

       "haldclut" also has the same interpolation options as lut3d (both
       filters share the same internals).

       More information about the Hald CLUT can be found on Eskil Steenberg's
       website (Hald CLUT author) at
       <http://www.quelsolaar.com/technology/clut.html>.

       Workflow examples

       Hald CLUT video stream

       Generate an identity Hald CLUT stream altered with various effects:

	       ffmpeg -f lavfi -i B<haldclutsrc>=8 -vf "hue=H=2*PI*t:s=sin(2*PI*t)+1, curves=cross_process" -t 10 -c:v ffv1 clut.nut

       Note: make sure you use a lossless codec.

       Then use it with "haldclut" to apply it on some random stream:

	       ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv

       The Hald CLUT will be applied to the 10 first seconds (duration of
       clut.nut), then the latest picture of that CLUT stream will be applied
       to the remaining frames of the "mandelbrot" stream.

       Hald CLUT with preview

       A Hald CLUT is supposed to be a squared image of "Level*Level*Level" by
       "Level*Level*Level" pixels. For a given Hald CLUT, FFmpeg will select
       the biggest possible square starting at the top left of the picture.
       The remaining padding pixels (bottom or right) will be ignored. This
       area can be used to add a preview of the Hald CLUT.

       Typically, the following generated Hald CLUT will be supported by the
       "haldclut" filter:

	       ffmpeg -f lavfi -i B<haldclutsrc>=8 -vf "
		  pad=iw+320 [padded_clut];
		  smptebars=s=320x256, split [a][b];
		  [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
		  [main][b] overlay=W-320" -frames:v 1 clut.png

       It contains the original and a preview of the effect of the CLUT: SMPTE
       color bars are displayed on the right-top, and below the same color
       bars processed by the color changes.

       Then, the effect of this Hald CLUT can be visualized with:

	       ffplay input.mkv -vf "movie=clut.png, [in] haldclut"

   hflip
       Flip the input video horizontally.

       For example, to horizontally flip the input video with ffmpeg:

	       ffmpeg -i in.avi -vf "hflip" out.avi

   histeq
       This filter applies a global color histogram equalization on a per-
       frame basis.

       It can be used to correct video that has a compressed range of pixel
       intensities.  The filter redistributes the pixel intensities to
       equalize their distribution across the intensity range. It may be
       viewed as an "automatically adjusting contrast filter". This filter is
       useful only for correcting degraded or poorly captured source video.

       The filter accepts the following options:

       strength
	   Determine the amount of equalization to be applied.	As the
	   strength is reduced, the distribution of pixel intensities more-
	   and-more approaches that of the input frame. The value must be a
	   float number in the range [0,1] and defaults to 0.200.

       intensity
	   Set the maximum intensity that can generated and scale the output
	   values appropriately.  The strength should be set as desired and
	   then the intensity can be limited if needed to avoid washing-out.
	   The value must be a float number in the range [0,1] and defaults to
	   0.210.

       antibanding
	   Set the antibanding level. If enabled the filter will randomly vary
	   the luminance of output pixels by a small amount to avoid banding
	   of the histogram. Possible values are "none", "weak" or "strong".
	   It defaults to "none".

   histogram
       Compute and draw a color distribution histogram for the input video.

       The computed histogram is a representation of the color component
       distribution in an image.

       Standard histogram displays the color components distribution in an
       image.  Displays color graph for each color component. Shows
       distribution of the Y, U, V, A or R, G, B components, depending on
       input format, in the current frame. Below each graph a color component
       scale meter is shown.

       The filter accepts the following options:

       level_height
	   Set height of level. Default value is 200.  Allowed range is [50,
	   2048].

       scale_height
	   Set height of color scale. Default value is 12.  Allowed range is
	   [0, 40].

       display_mode
	   Set display mode.  It accepts the following values:

	   stack
	       Per color component graphs are placed below each other.

	   parade
	       Per color component graphs are placed side by side.

	   overlay
	       Presents information identical to that in the "parade", except
	       that the graphs representing color components are superimposed
	       directly over one another.

	   Default is "stack".

       levels_mode
	   Set mode. Can be either "linear", or "logarithmic".	Default is
	   "linear".

       components
	   Set what color components to display.  Default is 7.

       fgopacity
	   Set foreground opacity. Default is 0.7.

       bgopacity
	   Set background opacity. Default is 0.5.

       Examples

       ·   Calculate and draw histogram:

		   ffplay -i input -vf histogram

   hqdn3d
       This is a high precision/quality 3d denoise filter. It aims to reduce
       image noise, producing smooth images and making still images really
       still. It should enhance compressibility.

       It accepts the following optional parameters:

       luma_spatial
	   A non-negative floating point number which specifies spatial luma
	   strength.  It defaults to 4.0.

       chroma_spatial
	   A non-negative floating point number which specifies spatial chroma
	   strength.  It defaults to 3.0*luma_spatial/4.0.

       luma_tmp
	   A floating point number which specifies luma temporal strength. It
	   defaults to 6.0*luma_spatial/4.0.

       chroma_tmp
	   A floating point number which specifies chroma temporal strength.
	   It defaults to luma_tmp*chroma_spatial/luma_spatial.

   hwdownload
       Download hardware frames to system memory.

       The input must be in hardware frames, and the output a non-hardware
       format.	Not all formats will be supported on the output - it may be
       necessary to insert an additional format filter immediately following
       in the graph to get the output in a supported format.

   hwmap
       Map hardware frames to system memory or to another device.

       This filter has several different modes of operation; which one is used
       depends on the input and output formats:

       ·   Hardware frame input, normal frame output

	   Map the input frames to system memory and pass them to the output.
	   If the original hardware frame is later required (for example,
	   after overlaying something else on part of it), the hwmap filter
	   can be used again in the next mode to retrieve it.

       ·   Normal frame input, hardware frame output

	   If the input is actually a software-mapped hardware frame, then
	   unmap it - that is, return the original hardware frame.

	   Otherwise, a device must be provided.  Create new hardware surfaces
	   on that device for the output, then map them back to the software
	   format at the input and give those frames to the preceding filter.
	   This will then act like the hwupload filter, but may be able to
	   avoid an additional copy when the input is already in a compatible
	   format.

       ·   Hardware frame input and output

	   A device must be supplied for the output, either directly or with
	   the derive_device option.  The input and output devices must be of
	   different types and compatible - the exact meaning of this is
	   system-dependent, but typically it means that they must refer to
	   the same underlying hardware context (for example, refer to the
	   same graphics card).

	   If the input frames were originally created on the output device,
	   then unmap to retrieve the original frames.

	   Otherwise, map the frames to the output device - create new
	   hardware frames on the output corresponding to the frames on the
	   input.

       The following additional parameters are accepted:

       mode
	   Set the frame mapping mode.	Some combination of:

	   read
	       The mapped frame should be readable.

	   write
	       The mapped frame should be writeable.

	   overwrite
	       The mapping will always overwrite the entire frame.

	       This may improve performance in some cases, as the original
	       contents of the frame need not be loaded.

	   direct
	       The mapping must not involve any copying.

	       Indirect mappings to copies of frames are created in some cases
	       where either direct mapping is not possible or it would have
	       unexpected properties.  Setting this flag ensures that the
	       mapping is direct and will fail if that is not possible.

	   Defaults to read+write if not specified.

       derive_device type
	   Rather than using the device supplied at initialisation, instead
	   derive a new device of type type from the device the input frames
	   exist on.

       reverse
	   In a hardware to hardware mapping, map in reverse - create frames
	   in the sink and map them back to the source.  This may be necessary
	   in some cases where a mapping in one direction is required but only
	   the opposite direction is supported by the devices being used.

	   This option is dangerous - it may break the preceding filter in
	   undefined ways if there are any additional constraints on that
	   filter's output.  Do not use it without fully understanding the
	   implications of its use.

   hwupload
       Upload system memory frames to hardware surfaces.

       The device to upload to must be supplied when the filter is
       initialised.  If using ffmpeg, select the appropriate device with the
       -filter_hw_device option.

   hwupload_cuda
       Upload system memory frames to a CUDA device.

       It accepts the following optional parameters:

       device
	   The number of the CUDA device to use

   hqx
       Apply a high-quality magnification filter designed for pixel art. This
       filter was originally created by Maxim Stepin.

       It accepts the following option:

       n   Set the scaling dimension: 2 for "hq2x", 3 for "hq3x" and 4 for
	   "hq4x".  Default is 3.

   hstack
       Stack input videos horizontally.

       All streams must be of same pixel format and of same height.

       Note that this filter is faster than using overlay and pad filter to
       create same output.

       The filter accept the following option:

       inputs
	   Set number of input streams. Default is 2.

       shortest
	   If set to 1, force the output to terminate when the shortest input
	   terminates. Default value is 0.

   hue
       Modify the hue and/or the saturation of the input.

       It accepts the following parameters:

       h   Specify the hue angle as a number of degrees. It accepts an
	   expression, and defaults to "0".

       s   Specify the saturation in the [-10,10] range. It accepts an
	   expression and defaults to "1".

       H   Specify the hue angle as a number of radians. It accepts an
	   expression, and defaults to "0".

       b   Specify the brightness in the [-10,10] range. It accepts an
	   expression and defaults to "0".

       h and H are mutually exclusive, and can't be specified at the same
       time.

       The b, h, H and s option values are expressions containing the
       following constants:

       n   frame count of the input frame starting from 0

       pts presentation timestamp of the input frame expressed in time base
	   units

       r   frame rate of the input video, NAN if the input frame rate is
	   unknown

       t   timestamp expressed in seconds, NAN if the input timestamp is
	   unknown

       tb  time base of the input video

       Examples

       ·   Set the hue to 90 degrees and the saturation to 1.0:

		   hue=h=90:s=1

       ·   Same command but expressing the hue in radians:

		   hue=H=PI/2:s=1

       ·   Rotate hue and make the saturation swing between 0 and 2 over a
	   period of 1 second:

		   hue="H=2*PI*t: s=sin(2*PI*t)+1"

       ·   Apply a 3 seconds saturation fade-in effect starting at 0:

		   hue="s=min(t/3\,1)"

	   The general fade-in expression can be written as:

		   hue="s=min(0\, max((t-START)/DURATION\, 1))"

       ·   Apply a 3 seconds saturation fade-out effect starting at 5 seconds:

		   hue="s=max(0\, min(1\, (8-t)/3))"

	   The general fade-out expression can be written as:

		   hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"

       Commands

       This filter supports the following commands:

       b
       s
       h
       H   Modify the hue and/or the saturation and/or brightness of the input
	   video.  The command accepts the same syntax of the corresponding
	   option.

	   If the specified expression is not valid, it is kept at its current
	   value.

   hysteresis
       Grow first stream into second stream by connecting components.  This
       makes it possible to build more robust edge masks.

       This filter accepts the following options:

       planes
	   Set which planes will be processed as bitmap, unprocessed planes
	   will be copied from first stream.  By default value 0xf, all planes
	   will be processed.

       threshold
	   Set threshold which is used in filtering. If pixel component value
	   is higher than this value filter algorithm for connecting
	   components is activated.  By default value is 0.

   idet
       Detect video interlacing type.

       This filter tries to detect if the input frames are interlaced,
       progressive, top or bottom field first. It will also try to detect
       fields that are repeated between adjacent frames (a sign of telecine).

       Single frame detection considers only immediately adjacent frames when
       classifying each frame.	Multiple frame detection incorporates the
       classification history of previous frames.

       The filter will log these metadata values:

       single.current_frame
	   Detected type of current frame using single-frame detection. One
	   of: ``tff'' (top field first), ``bff'' (bottom field first),
	   ``progressive'', or ``undetermined''

       single.tff
	   Cumulative number of frames detected as top field first using
	   single-frame detection.

       multiple.tff
	   Cumulative number of frames detected as top field first using
	   multiple-frame detection.

       single.bff
	   Cumulative number of frames detected as bottom field first using
	   single-frame detection.

       multiple.current_frame
	   Detected type of current frame using multiple-frame detection. One
	   of: ``tff'' (top field first), ``bff'' (bottom field first),
	   ``progressive'', or ``undetermined''

       multiple.bff
	   Cumulative number of frames detected as bottom field first using
	   multiple-frame detection.

       single.progressive
	   Cumulative number of frames detected as progressive using single-
	   frame detection.

       multiple.progressive
	   Cumulative number of frames detected as progressive using multiple-
	   frame detection.

       single.undetermined
	   Cumulative number of frames that could not be classified using
	   single-frame detection.

       multiple.undetermined
	   Cumulative number of frames that could not be classified using
	   multiple-frame detection.

       repeated.current_frame
	   Which field in the current frame is repeated from the last. One of
	   ``neither'', ``top'', or ``bottom''.

       repeated.neither
	   Cumulative number of frames with no repeated field.

       repeated.top
	   Cumulative number of frames with the top field repeated from the
	   previous frame's top field.

       repeated.bottom
	   Cumulative number of frames with the bottom field repeated from the
	   previous frame's bottom field.

       The filter accepts the following options:

       intl_thres
	   Set interlacing threshold.

       prog_thres
	   Set progressive threshold.

       rep_thres
	   Threshold for repeated field detection.

       half_life
	   Number of frames after which a given frame's contribution to the
	   statistics is halved (i.e., it contributes only 0.5 to its
	   classification). The default of 0 means that all frames seen are
	   given full weight of 1.0 forever.

       analyze_interlaced_flag
	   When this is not 0 then idet will use the specified number of
	   frames to determine if the interlaced flag is accurate, it will not
	   count undetermined frames.  If the flag is found to be accurate it
	   will be used without any further computations, if it is found to be
	   inaccurate it will be cleared without any further computations.
	   This allows inserting the idet filter as a low computational method
	   to clean up the interlaced flag

   il
       Deinterleave or interleave fields.

       This filter allows one to process interlaced images fields without
       deinterlacing them. Deinterleaving splits the input frame into 2 fields
       (so called half pictures). Odd lines are moved to the top half of the
       output image, even lines to the bottom half.  You can process (filter)
       them independently and then re-interleave them.

       The filter accepts the following options:

       luma_mode, l
       chroma_mode, c
       alpha_mode, a
	   Available values for luma_mode, chroma_mode and alpha_mode are:

	   none
	       Do nothing.

	   deinterleave, d
	       Deinterleave fields, placing one above the other.

	   interleave, i
	       Interleave fields. Reverse the effect of deinterleaving.

	   Default value is "none".

       luma_swap, ls
       chroma_swap, cs
       alpha_swap, as
	   Swap luma/chroma/alpha fields. Exchange even & odd lines. Default
	   value is 0.

   inflate
       Apply inflate effect to the video.

       This filter replaces the pixel by the local(3x3) average by taking into
       account only values higher than the pixel.

       It accepts the following options:

       threshold0
       threshold1
       threshold2
       threshold3
	   Limit the maximum change for each plane, default is 65535.  If 0,
	   plane will remain unchanged.

   interlace
       Simple interlacing filter from progressive contents. This interleaves
       upper (or lower) lines from odd frames with lower (or upper) lines from
       even frames, halving the frame rate and preserving image height.

		  Original	  Original	       New Frame
		  Frame 'j'	 Frame 'j+1'		 (tff)
		 ==========	 ===========	   ==================
		   Line 0  -------------------->    Frame 'j' Line 0
		   Line 1	   Line 1  ---->   Frame 'j+1' Line 1
		   Line 2 --------------------->    Frame 'j' Line 2
		   Line 3	   Line 3  ---->   Frame 'j+1' Line 3
		    ... 	    ... 		  ...
	       New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on

       It accepts the following optional parameters:

       scan
	   This determines whether the interlaced frame is taken from the even
	   (tff - default) or odd (bff) lines of the progressive frame.

       lowpass
	   Vertical lowpass filter to avoid twitter interlacing and reduce
	   moire patterns.

	   0, off
	       Disable vertical lowpass filter

	   1, linear
	       Enable linear filter (default)

	   2, complex
	       Enable complex filter. This will slightly less reduce twitter
	       and moire but better retain detail and subjective sharpness
	       impression.

   kerndeint
       Deinterlace input video by applying Donald Graft's adaptive kernel
       deinterling. Work on interlaced parts of a video to produce progressive
       frames.

       The description of the accepted parameters follows.

       thresh
	   Set the threshold which affects the filter's tolerance when
	   determining if a pixel line must be processed. It must be an
	   integer in the range [0,255] and defaults to 10. A value of 0 will
	   result in applying the process on every pixels.

       map Paint pixels exceeding the threshold value to white if set to 1.
	   Default is 0.

       order
	   Set the fields order. Swap fields if set to 1, leave fields alone
	   if 0. Default is 0.

       sharp
	   Enable additional sharpening if set to 1. Default is 0.

       twoway
	   Enable twoway sharpening if set to 1. Default is 0.

       Examples

       ·   Apply default values:

		   kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0

       ·   Enable additional sharpening:

		   kerndeint=sharp=1

       ·   Paint processed pixels in white:

		   kerndeint=map=1

   lenscorrection
       Correct radial lens distortion

       This filter can be used to correct for radial distortion as can result
       from the use of wide angle lenses, and thereby re-rectify the image. To
       find the right parameters one can use tools available for example as
       part of opencv or simply trial-and-error.  To use opencv use the
       calibration sample (under samples/cpp) from the opencv sources and
       extract the k1 and k2 coefficients from the resulting matrix.

       Note that effectively the same filter is available in the open-source
       tools Krita and Digikam from the KDE project.

       In contrast to the vignette filter, which can also be used to
       compensate lens errors, this filter corrects the distortion of the
       image, whereas vignette corrects the brightness distribution, so you
       may want to use both filters together in certain cases, though you will
       have to take care of ordering, i.e. whether vignetting should be
       applied before or after lens correction.

       Options

       The filter accepts the following options:

       cx  Relative x-coordinate of the focal point of the image, and thereby
	   the center of the distortion. This value has a range [0,1] and is
	   expressed as fractions of the image width. Default is 0.5.

       cy  Relative y-coordinate of the focal point of the image, and thereby
	   the center of the distortion. This value has a range [0,1] and is
	   expressed as fractions of the image height. Default is 0.5.

       k1  Coefficient of the quadratic correction term. This value has a
	   range [-1,1]. 0 means no correction. Default is 0.

       k2  Coefficient of the double quadratic correction term. This value has
	   a range [-1,1].  0 means no correction. Default is 0.

       The formula that generates the correction is:

       r_src = r_tgt * (1 + k1 * (r_tgt / r_0)^2 + k2 * (r_tgt / r_0)^4)

       where r_0 is halve of the image diagonal and r_src and r_tgt are the
       distances from the focal point in the source and target images,
       respectively.

   lensfun
       Apply lens correction via the lensfun library
       (<http://lensfun.sourceforge.net/>).

       The "lensfun" filter requires the camera make, camera model, and lens
       model to apply the lens correction. The filter will load the lensfun
       database and query it to find the corresponding camera and lens entries
       in the database. As long as these entries can be found with the given
       options, the filter can perform corrections on frames. Note that
       incomplete strings will result in the filter choosing the best match
       with the given options, and the filter will output the chosen camera
       and lens models (logged with level "info"). You must provide the make,
       camera model, and lens model as they are required.

       The filter accepts the following options:

       make
	   The make of the camera (for example, "Canon"). This option is
	   required.

       model
	   The model of the camera (for example, "Canon EOS 100D"). This
	   option is required.

       lens_model
	   The model of the lens (for example, "Canon EF-S 18-55mm f/3.5-5.6
	   IS STM"). This option is required.

       mode
	   The type of correction to apply. The following values are valid
	   options:

	   vignetting
	       Enables fixing lens vignetting.

	   geometry
	       Enables fixing lens geometry. This is the default.

	   subpixel
	       Enables fixing chromatic aberrations.

	   vig_geo
	       Enables fixing lens vignetting and lens geometry.

	   vig_subpixel
	       Enables fixing lens vignetting and chromatic aberrations.

	   distortion
	       Enables fixing both lens geometry and chromatic aberrations.

	   all Enables all possible corrections.

       focal_length
	   The focal length of the image/video (zoom; expected constant for
	   video). For example, a 18--55mm lens has focal length range of
	   [18--55], so a value in that range should be chosen when using that
	   lens. Default 18.

       aperture
	   The aperture of the image/video (expected constant for video). Note
	   that aperture is only used for vignetting correction. Default 3.5.

       focus_distance
	   The focus distance of the image/video (expected constant for
	   video). Note that focus distance is only used for vignetting and
	   only slightly affects the vignetting correction process. If
	   unknown, leave it at the default value (which is 1000).

       target_geometry
	   The target geometry of the output image/video. The following values
	   are valid options:

	   rectilinear (default)
	   fisheye
	   panoramic
	   equirectangular
	   fisheye_orthographic
	   fisheye_stereographic
	   fisheye_equisolid
	   fisheye_thoby
       reverse
	   Apply the reverse of image correction (instead of correcting
	   distortion, apply it).

       interpolation
	   The type of interpolation used when correcting distortion. The
	   following values are valid options:

	   nearest
	   linear (default)
	   lanczos

       Examples

       ·   Apply lens correction with make "Canon", camera model "Canon EOS
	   100D", and lens model "Canon EF-S 18-55mm f/3.5-5.6 IS STM" with
	   focal length of "18" and aperture of "8.0".

		   ffmpeg -i input.mov -vf lensfun=make=Canon:model="Canon EOS 100D":lens_model="Canon EF-S 18-55mm f/3.5-5.6 IS STM":focal_length=18:aperture=8 -c:v h264 -b:v 8000k output.mov

       ·   Apply the same as before, but only for the first 5 seconds of
	   video.

		   ffmpeg -i input.mov -vf lensfun=make=Canon:model="Canon EOS 100D":lens_model="Canon EF-S 18-55mm f/3.5-5.6 IS STM":focal_length=18:aperture=8:enable='lte(t\,5)' -c:v h264 -b:v 8000k output.mov

   libvmaf
       Obtain the VMAF (Video Multi-Method Assessment Fusion) score between
       two input videos.

       The obtained VMAF score is printed through the logging system.

       It requires Netflix's vmaf library (libvmaf) as a pre-requisite.  After
       installing the library it can be enabled using: "./configure
       --enable-libvmaf --enable-version3".  If no model path is specified it
       uses the default model: "vmaf_v0.6.1.pkl".

       The filter has following options:

       model_path
	   Set the model path which is to be used for SVM.  Default value:
	   "vmaf_v0.6.1.pkl"

       log_path
	   Set the file path to be used to store logs.

       log_fmt
	   Set the format of the log file (xml or json).

       enable_transform
	   Enables transform for computing vmaf.

       phone_model
	   Invokes the phone model which will generate VMAF scores higher than
	   in the regular model, which is more suitable for laptop, TV, etc.
	   viewing conditions.

       psnr
	   Enables computing psnr along with vmaf.

       ssim
	   Enables computing ssim along with vmaf.

       ms_ssim
	   Enables computing ms_ssim along with vmaf.

       pool
	   Set the pool method (mean, min or harmonic mean) to be used for
	   computing vmaf.

       n_threads
	   Set number of threads to be used when computing vmaf.

       n_subsample
	   Set interval for frame subsampling used when computing vmaf.

       enable_conf_interval
	   Enables confidence interval.

       This filter also supports the framesync options.

       On the below examples the input file main.mpg being processed is
       compared with the reference file ref.mpg.

	       ffmpeg -i main.mpg -i ref.mpg -lavfi libvmaf -f null -

       Example with options:

	       ffmpeg -i main.mpg -i ref.mpg -lavfi libvmaf="psnr=1:enable-transform=1" -f null -

   limiter
       Limits the pixel components values to the specified range [min, max].

       The filter accepts the following options:

       min Lower bound. Defaults to the lowest allowed value for the input.

       max Upper bound. Defaults to the highest allowed value for the input.

       planes
	   Specify which planes will be processed. Defaults to all available.

   loop
       Loop video frames.

       The filter accepts the following options:

       loop
	   Set the number of loops. Setting this value to -1 will result in
	   infinite loops.  Default is 0.

       size
	   Set maximal size in number of frames. Default is 0.

       start
	   Set first frame of loop. Default is 0.

   lut3d
       Apply a 3D LUT to an input video.

       The filter accepts the following options:

       file
	   Set the 3D LUT file name.

	   Currently supported formats:

	   3dl AfterEffects

	   cube
	       Iridas

	   dat DaVinci

	   m3d Pandora

       interp
	   Select interpolation mode.

	   Available values are:

	   nearest
	       Use values from the nearest defined point.

	   trilinear
	       Interpolate values using the 8 points defining a cube.

	   tetrahedral
	       Interpolate values using a tetrahedron.

       This filter also supports the framesync options.

   lumakey
       Turn certain luma values into transparency.

       The filter accepts the following options:

       threshold
	   Set the luma which will be used as base for transparency.  Default
	   value is 0.

       tolerance
	   Set the range of luma values to be keyed out.  Default value is 0.

       softness
	   Set the range of softness. Default value is 0.  Use this to control
	   gradual transition from zero to full transparency.

   lut, lutrgb, lutyuv
       Compute a look-up table for binding each pixel component input value to
       an output value, and apply it to the input video.

       lutyuv applies a lookup table to a YUV input video, lutrgb to an RGB
       input video.

       These filters accept the following parameters:

       c0  set first pixel component expression

       c1  set second pixel component expression

       c2  set third pixel component expression

       c3  set fourth pixel component expression, corresponds to the alpha
	   component

       r   set red component expression

       g   set green component expression

       b   set blue component expression

       a   alpha component expression

       y   set Y/luminance component expression

       u   set U/Cb component expression

       v   set V/Cr component expression

       Each of them specifies the expression to use for computing the lookup
       table for the corresponding pixel component values.

       The exact component associated to each of the c* options depends on the
       format in input.

       The lut filter requires either YUV or RGB pixel formats in input,
       lutrgb requires RGB pixel formats in input, and lutyuv requires YUV.

       The expressions can contain the following constants and functions:

       w
       h   The input width and height.

       val The input value for the pixel component.

       clipval
	   The input value, clipped to the minval-maxval range.

       maxval
	   The maximum value for the pixel component.

       minval
	   The minimum value for the pixel component.

       negval
	   The negated value for the pixel component value, clipped to the
	   minval-maxval range; it corresponds to the expression
	   "maxval-clipval+minval".

       clip(val)
	   The computed value in val, clipped to the minval-maxval range.

       gammaval(gamma)
	   The computed gamma correction value of the pixel component value,
	   clipped to the minval-maxval range. It corresponds to the
	   expression
	   "pow((clipval-minval)/(maxval-minval)\,gamma)*(maxval-minval)+minval"

       All expressions default to "val".

       Examples

       ·   Negate input video:

		   lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
		   lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"

	   The above is the same as:

		   lutrgb="r=negval:g=negval:b=negval"
		   lutyuv="y=negval:u=negval:v=negval"

       ·   Negate luminance:

		   lutyuv=y=negval

       ·   Remove chroma components, turning the video into a graytone image:

		   lutyuv="u=128:v=128"

       ·   Apply a luma burning effect:

		   lutyuv="y=2*val"

       ·   Remove green and blue components:

		   lutrgb="g=0:b=0"

       ·   Set a constant alpha channel value on input:

		   format=rgba,lutrgb=a="maxval-minval/2"

       ·   Correct luminance gamma by a factor of 0.5:

		   lutyuv=y=gammaval(0.5)

       ·   Discard least significant bits of luma:

		   lutyuv=y='bitand(val, 128+64+32)'

       ·   Technicolor like effect:

		   lutyuv=u='(val-maxval/2)*2+maxval/2':v='(val-maxval/2)*2+maxval/2'

   lut2, tlut2
       The "lut2" filter takes two input streams and outputs one stream.

       The "tlut2" (time lut2) filter takes two consecutive frames from one
       single stream.

       This filter accepts the following parameters:

       c0  set first pixel component expression

       c1  set second pixel component expression

       c2  set third pixel component expression

       c3  set fourth pixel component expression, corresponds to the alpha
	   component

       Each of them specifies the expression to use for computing the lookup
       table for the corresponding pixel component values.

       The exact component associated to each of the c* options depends on the
       format in inputs.

       The expressions can contain the following constants:

       w
       h   The input width and height.

       x   The first input value for the pixel component.

       y   The second input value for the pixel component.

       bdx The first input video bit depth.

       bdy The second input video bit depth.

       All expressions default to "x".

       Examples

       ·   Highlight differences between two RGB video streams:

		   lut2='ifnot(x-y,0,pow(2,bdx)-1):ifnot(x-y,0,pow(2,bdx)-1):ifnot(x-y,0,pow(2,bdx)-1)'

       ·   Highlight differences between two YUV video streams:

		   lut2='ifnot(x-y,0,pow(2,bdx)-1):ifnot(x-y,pow(2,bdx-1),pow(2,bdx)-1):ifnot(x-y,pow(2,bdx-1),pow(2,bdx)-1)'

       ·   Show max difference between two video streams:

		   lut2='if(lt(x,y),0,if(gt(x,y),pow(2,bdx)-1,pow(2,bdx-1))):if(lt(x,y),0,if(gt(x,y),pow(2,bdx)-1,pow(2,bdx-1))):if(lt(x,y),0,if(gt(x,y),pow(2,bdx)-1,pow(2,bdx-1)))'

   maskedclamp
       Clamp the first input stream with the second input and third input
       stream.

       Returns the value of first stream to be between second input stream -
       "undershoot" and third input stream + "overshoot".

       This filter accepts the following options:

       undershoot
	   Default value is 0.

       overshoot
	   Default value is 0.

       planes
	   Set which planes will be processed as bitmap, unprocessed planes
	   will be copied from first stream.  By default value 0xf, all planes
	   will be processed.

   maskedmerge
       Merge the first input stream with the second input stream using per
       pixel weights in the third input stream.

       A value of 0 in the third stream pixel component means that pixel
       component from first stream is returned unchanged, while maximum value
       (eg. 255 for 8-bit videos) means that pixel component from second
       stream is returned unchanged. Intermediate values define the amount of
       merging between both input stream's pixel components.

       This filter accepts the following options:

       planes
	   Set which planes will be processed as bitmap, unprocessed planes
	   will be copied from first stream.  By default value 0xf, all planes
	   will be processed.

   mcdeint
       Apply motion-compensation deinterlacing.

       It needs one field per frame as input and must thus be used together
       with yadif=1/3 or equivalent.

       This filter accepts the following options:

       mode
	   Set the deinterlacing mode.

	   It accepts one of the following values:

	   fast
	   medium
	   slow
	       use iterative motion estimation

	   extra_slow
	       like slow, but use multiple reference frames.

	   Default value is fast.

       parity
	   Set the picture field parity assumed for the input video. It must
	   be one of the following values:

	   0, tff
	       assume top field first

	   1, bff
	       assume bottom field first

	   Default value is bff.

       qp  Set per-block quantization parameter (QP) used by the internal
	   encoder.

	   Higher values should result in a smoother motion vector field but
	   less optimal individual vectors. Default value is 1.

   mergeplanes
       Merge color channel components from several video streams.

       The filter accepts up to 4 input streams, and merge selected input
       planes to the output video.

       This filter accepts the following options:

       mapping
	   Set input to output plane mapping. Default is 0.

	   The mappings is specified as a bitmap. It should be specified as a
	   hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the
	   mapping for the first plane of the output stream. 'A' sets the
	   number of the input stream to use (from 0 to 3), and 'a' the plane
	   number of the corresponding input to use (from 0 to 3). The rest of
	   the mappings is similar, 'Bb' describes the mapping for the output
	   stream second plane, 'Cc' describes the mapping for the output
	   stream third plane and 'Dd' describes the mapping for the output
	   stream fourth plane.

       format
	   Set output pixel format. Default is "yuva444p".

       Examples

       ·   Merge three gray video streams of same width and height into single
	   video stream:

		   [a0][a1][a2]mergeplanes=0x001020:yuv444p

       ·   Merge 1st yuv444p stream and 2nd gray video stream into yuva444p
	   video stream:

		   [a0][a1]mergeplanes=0x00010210:yuva444p

       ·   Swap Y and A plane in yuva444p stream:

		   format=yuva444p,mergeplanes=0x03010200:yuva444p

       ·   Swap U and V plane in yuv420p stream:

		   format=yuv420p,mergeplanes=0x000201:yuv420p

       ·   Cast a rgb24 clip to yuv444p:

		   format=rgb24,mergeplanes=0x000102:yuv444p

   mestimate
       Estimate and export motion vectors using block matching algorithms.
       Motion vectors are stored in frame side data to be used by other
       filters.

       This filter accepts the following options:

       method
	   Specify the motion estimation method. Accepts one of the following
	   values:

	   esa Exhaustive search algorithm.

	   tss Three step search algorithm.

	   tdls
	       Two dimensional logarithmic search algorithm.

	   ntss
	       New three step search algorithm.

	   fss Four step search algorithm.

	   ds  Diamond search algorithm.

	   hexbs
	       Hexagon-based search algorithm.

	   epzs
	       Enhanced predictive zonal search algorithm.

	   umh Uneven multi-hexagon search algorithm.

	   Default value is esa.

       mb_size
	   Macroblock size. Default 16.

       search_param
	   Search parameter. Default 7.

   midequalizer
       Apply Midway Image Equalization effect using two video streams.

       Midway Image Equalization adjusts a pair of images to have the same
       histogram, while maintaining their dynamics as much as possible. It's
       useful for e.g. matching exposures from a pair of stereo cameras.

       This filter has two inputs and one output, which must be of same pixel
       format, but may be of different sizes. The output of filter is first
       input adjusted with midway histogram of both inputs.

       This filter accepts the following option:

       planes
	   Set which planes to process. Default is 15, which is all available
	   planes.

   minterpolate
       Convert the video to specified frame rate using motion interpolation.

       This filter accepts the following options:

       fps Specify the output frame rate. This can be rational e.g.
	   "60000/1001". Frames are dropped if fps is lower than source fps.
	   Default 60.

       mi_mode
	   Motion interpolation mode. Following values are accepted:

	   dup Duplicate previous or next frame for interpolating new ones.

	   blend
	       Blend source frames. Interpolated frame is mean of previous and
	       next frames.

	   mci Motion compensated interpolation. Following options are
	       effective when this mode is selected:

	       mc_mode
		   Motion compensation mode. Following values are accepted:

		   obmc
		       Overlapped block motion compensation.

		   aobmc
		       Adaptive overlapped block motion compensation. Window
		       weighting coefficients are controlled adaptively
		       according to the reliabilities of the neighboring
		       motion vectors to reduce oversmoothing.

		   Default mode is obmc.

	       me_mode
		   Motion estimation mode. Following values are accepted:

		   bidir
		       Bidirectional motion estimation. Motion vectors are
		       estimated for each source frame in both forward and
		       backward directions.

		   bilat
		       Bilateral motion estimation. Motion vectors are
		       estimated directly for interpolated frame.

		   Default mode is bilat.

	       me  The algorithm to be used for motion estimation. Following
		   values are accepted:

		   esa Exhaustive search algorithm.

		   tss Three step search algorithm.

		   tdls
		       Two dimensional logarithmic search algorithm.

		   ntss
		       New three step search algorithm.

		   fss Four step search algorithm.

		   ds  Diamond search algorithm.

		   hexbs
		       Hexagon-based search algorithm.

		   epzs
		       Enhanced predictive zonal search algorithm.

		   umh Uneven multi-hexagon search algorithm.

		   Default algorithm is epzs.

	       mb_size
		   Macroblock size. Default 16.

	       search_param
		   Motion estimation search parameter. Default 32.

	       vsbmc
		   Enable variable-size block motion compensation. Motion
		   estimation is applied with smaller block sizes at object
		   boundaries in order to make the them less blur. Default is
		   0 (disabled).

       scd Scene change detection method. Scene change leads motion vectors to
	   be in random direction. Scene change detection replace interpolated
	   frames by duplicate ones. May not be needed for other modes.
	   Following values are accepted:

	   none
	       Disable scene change detection.

	   fdiff
	       Frame difference. Corresponding pixel values are compared and
	       if it satisfies scd_threshold scene change is detected.

	   Default method is fdiff.

       scd_threshold
	   Scene change detection threshold. Default is 5.0.

   mix
       Mix several video input streams into one video stream.

       A description of the accepted options follows.

       nb_inputs
	   The number of inputs. If unspecified, it defaults to 2.

       weights
	   Specify weight of each input video stream as sequence.  Each weight
	   is separated by space. If number of weights is smaller than number
	   of frames last specified weight will be used for all remaining
	   unset weights.

       scale
	   Specify scale, if it is set it will be multiplied with sum of each
	   weight multiplied with pixel values to give final destination pixel
	   value. By default scale is auto scaled to sum of weights.

       duration
	   Specify how end of stream is determined.

	   longest
	       The duration of the longest input. (default)

	   shortest
	       The duration of the shortest input.

	   first
	       The duration of the first input.

   mpdecimate
       Drop frames that do not differ greatly from the previous frame in order
       to reduce frame rate.

       The main use of this filter is for very-low-bitrate encoding (e.g.
       streaming over dialup modem), but it could in theory be used for fixing
       movies that were inverse-telecined incorrectly.

       A description of the accepted options follows.

       max Set the maximum number of consecutive frames which can be dropped
	   (if positive), or the minimum interval between dropped frames (if
	   negative). If the value is 0, the frame is dropped disregarding the
	   number of previous sequentially dropped frames.

	   Default value is 0.

       hi
       lo
       frac
	   Set the dropping threshold values.

	   Values for hi and lo are for 8x8 pixel blocks and represent actual
	   pixel value differences, so a threshold of 64 corresponds to 1 unit
	   of difference for each pixel, or the same spread out differently
	   over the block.

	   A frame is a candidate for dropping if no 8x8 blocks differ by more
	   than a threshold of hi, and if no more than frac blocks (1 meaning
	   the whole image) differ by more than a threshold of lo.

	   Default value for hi is 64*12, default value for lo is 64*5, and
	   default value for frac is 0.33.

   negate
       Negate (invert) the input video.

       It accepts the following option:

       negate_alpha
	   With value 1, it negates the alpha component, if present. Default
	   value is 0.

   nlmeans
       Denoise frames using Non-Local Means algorithm.

       Each pixel is adjusted by looking for other pixels with similar
       contexts. This context similarity is defined by comparing their
       surrounding patches of size pxp. Patches are searched in an area of rxr
       around the pixel.

       Note that the research area defines centers for patches, which means
       some patches will be made of pixels outside that research area.

       The filter accepts the following options.

       s   Set denoising strength.

       p   Set patch size.

       pc  Same as p but for chroma planes.

	   The default value is 0 and means automatic.

       r   Set research size.

       rc  Same as r but for chroma planes.

	   The default value is 0 and means automatic.

   nnedi
       Deinterlace video using neural network edge directed interpolation.

       This filter accepts the following options:

       weights
	   Mandatory option, without binary file filter can not work.
	   Currently file can be found here:
	   https://github.com/dubhater/vapoursynth-nnedi3/blob/master/src/nnedi3_weights.bin

       deint
	   Set which frames to deinterlace, by default it is "all".  Can be
	   "all" or "interlaced".

       field
	   Set mode of operation.

	   Can be one of the following:

	   af  Use frame flags, both fields.

	   a   Use frame flags, single field.

	   t   Use top field only.

	   b   Use bottom field only.

	   tf  Use both fields, top first.

	   bf  Use both fields, bottom first.

       planes
	   Set which planes to process, by default filter process all frames.

       nsize
	   Set size of local neighborhood around each pixel, used by the
	   predictor neural network.

	   Can be one of the following:

	   s8x6
	   s16x6
	   s32x6
	   s48x6
	   s8x4
	   s16x4
	   s32x4
       nns Set the number of neurons in predictor neural network.  Can be one
	   of the following:

	   n16
	   n32
	   n64
	   n128
	   n256
       qual
	   Controls the number of different neural network predictions that
	   are blended together to compute the final output value. Can be
	   "fast", default or "slow".

       etype
	   Set which set of weights to use in the predictor.  Can be one of
	   the following:

	   a   weights trained to minimize absolute error

	   s   weights trained to minimize squared error

       pscrn
	   Controls whether or not the prescreener neural network is used to
	   decide which pixels should be processed by the predictor neural
	   network and which can be handled by simple cubic interpolation.
	   The prescreener is trained to know whether cubic interpolation will
	   be sufficient for a pixel or whether it should be predicted by the
	   predictor nn.  The computational complexity of the prescreener nn
	   is much less than that of the predictor nn. Since most pixels can
	   be handled by cubic interpolation, using the prescreener generally
	   results in much faster processing.  The prescreener is pretty
	   accurate, so the difference between using it and not using it is
	   almost always unnoticeable.

	   Can be one of the following:

	   none
	   original
	   new

	   Default is "new".

       fapprox
	   Set various debugging flags.

   noformat
       Force libavfilter not to use any of the specified pixel formats for the
       input to the next filter.

       It accepts the following parameters:

       pix_fmts
	   A '|'-separated list of pixel format names, such as
	   pix_fmts=yuv420p|monow|rgb24".

       Examples

       ·   Force libavfilter to use a format different from yuv420p for the
	   input to the vflip filter:

		   noformat=pix_fmts=yuv420p,vflip

       ·   Convert the input video to any of the formats not contained in the
	   list:

		   noformat=yuv420p|yuv444p|yuv410p

   noise
       Add noise on video input frame.

       The filter accepts the following options:

       all_seed
       c0_seed
       c1_seed
       c2_seed
       c3_seed
	   Set noise seed for specific pixel component or all pixel components
	   in case of all_seed. Default value is 123457.

       all_strength, alls
       c0_strength, c0s
       c1_strength, c1s
       c2_strength, c2s
       c3_strength, c3s
	   Set noise strength for specific pixel component or all pixel
	   components in case all_strength. Default value is 0. Allowed range
	   is [0, 100].

       all_flags, allf
       c0_flags, c0f
       c1_flags, c1f
       c2_flags, c2f
       c3_flags, c3f
	   Set pixel component flags or set flags for all components if
	   all_flags.  Available values for component flags are:

	   a   averaged temporal noise (smoother)

	   p   mix random noise with a (semi)regular pattern

	   t   temporal noise (noise pattern changes between frames)

	   u   uniform noise (gaussian otherwise)

       Examples

       Add temporal and uniform noise to input video:

	       noise=alls=20:allf=t+u

   normalize
       Normalize RGB video (aka histogram stretching, contrast stretching).
       See: https://en.wikipedia.org/wiki/Normalization_(image_processing)

       For each channel of each frame, the filter computes the input range and
       maps it linearly to the user-specified output range. The output range
       defaults to the full dynamic range from pure black to pure white.

       Temporal smoothing can be used on the input range to reduce flickering
       (rapid changes in brightness) caused when small dark or bright objects
       enter or leave the scene. This is similar to the auto-exposure
       (automatic gain control) on a video camera, and, like a video camera,
       it may cause a period of over- or under-exposure of the video.

       The R,G,B channels can be normalized independently, which may cause
       some color shifting, or linked together as a single channel, which
       prevents color shifting. Linked normalization preserves hue.
       Independent normalization does not, so it can be used to remove some
       color casts. Independent and linked normalization can be combined in
       any ratio.

       The normalize filter accepts the following options:

       blackpt
       whitept
	   Colors which define the output range. The minimum input value is
	   mapped to the blackpt. The maximum input value is mapped to the
	   whitept.  The defaults are black and white respectively. Specifying
	   white for blackpt and black for whitept will give color-inverted,
	   normalized video. Shades of grey can be used to reduce the dynamic
	   range (contrast). Specifying saturated colors here can create some
	   interesting effects.

       smoothing
	   The number of previous frames to use for temporal smoothing. The
	   input range of each channel is smoothed using a rolling average
	   over the current frame and the smoothing previous frames. The
	   default is 0 (no temporal smoothing).

       independence
	   Controls the ratio of independent (color shifting) channel
	   normalization to linked (color preserving) normalization. 0.0 is
	   fully linked, 1.0 is fully independent. Defaults to 1.0 (fully
	   independent).

       strength
	   Overall strength of the filter. 1.0 is full strength. 0.0 is a
	   rather expensive no-op. Defaults to 1.0 (full strength).

       Examples

       Stretch video contrast to use the full dynamic range, with no temporal
       smoothing; may flicker depending on the source content:

	       normalize=blackpt=black:whitept=white:smoothing=0

       As above, but with 50 frames of temporal smoothing; flicker should be
       reduced, depending on the source content:

	       normalize=blackpt=black:whitept=white:smoothing=50

       As above, but with hue-preserving linked channel normalization:

	       normalize=blackpt=black:whitept=white:smoothing=50:independence=0

       As above, but with half strength:

	       normalize=blackpt=black:whitept=white:smoothing=50:independence=0:strength=0.5

       Map the darkest input color to red, the brightest input color to cyan:

	       normalize=blackpt=red:whitept=cyan

   null
       Pass the video source unchanged to the output.

   ocr
       Optical Character Recognition

       This filter uses Tesseract for optical character recognition. To enable
       compilation of this filter, you need to configure FFmpeg with
       "--enable-libtesseract".

       It accepts the following options:

       datapath
	   Set datapath to tesseract data. Default is to use whatever was set
	   at installation.

       language
	   Set language, default is "eng".

       whitelist
	   Set character whitelist.

       blacklist
	   Set character blacklist.

       The filter exports recognized text as the frame metadata
       "lavfi.ocr.text".

   ocv
       Apply a video transform using libopencv.

       To enable this filter, install the libopencv library and headers and
       configure FFmpeg with "--enable-libopencv".

       It accepts the following parameters:

       filter_name
	   The name of the libopencv filter to apply.

       filter_params
	   The parameters to pass to the libopencv filter. If not specified,
	   the default values are assumed.

       Refer to the official libopencv documentation for more precise
       information:
       <http://docs.opencv.org/master/modules/imgproc/doc/filtering.html>

       Several libopencv filters are supported; see the following subsections.

       dilate

       Dilate an image by using a specific structuring element.  It
       corresponds to the libopencv function "cvDilate".

       It accepts the parameters: struct_el|nb_iterations.

       struct_el represents a structuring element, and has the syntax:
       colsxrows+anchor_xxanchor_y/shape

       cols and rows represent the number of columns and rows of the
       structuring element, anchor_x and anchor_y the anchor point, and shape
       the shape for the structuring element. shape must be "rect", "cross",
       "ellipse", or "custom".

       If the value for shape is "custom", it must be followed by a string of
       the form "=filename". The file with name filename is assumed to
       represent a binary image, with each printable character corresponding
       to a bright pixel. When a custom shape is used, cols and rows are
       ignored, the number or columns and rows of the read file are assumed
       instead.

       The default value for struct_el is "3x3+0x0/rect".

       nb_iterations specifies the number of times the transform is applied to
       the image, and defaults to 1.

       Some examples:

	       # Use the default values
	       ocv=dilate

	       # Dilate using a structuring element with a 5x5 cross, iterating two times
	       ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2

	       # Read the shape from the file diamond.shape, iterating two times.
	       # The file diamond.shape may contain a pattern of characters like this
	       #   *
	       #  ***
	       # *****
	       #  ***
	       #   *
	       # The specified columns and rows are ignored
	       # but the anchor point coordinates are not
	       ocv=dilate:0x0+2x2/custom=diamond.shape|2

       erode

       Erode an image by using a specific structuring element.	It corresponds
       to the libopencv function "cvErode".

       It accepts the parameters: struct_el:nb_iterations, with the same
       syntax and semantics as the dilate filter.

       smooth

       Smooth the input video.

       The filter takes the following parameters:
       type|param1|param2|param3|param4.

       type is the type of smooth filter to apply, and must be one of the
       following values: "blur", "blur_no_scale", "median", "gaussian", or
       "bilateral". The default value is "gaussian".

       The meaning of param1, param2, param3, and param4 depend on the smooth
       type. param1 and param2 accept integer positive values or 0. param3 and
       param4 accept floating point values.

       The default value for param1 is 3. The default value for the other
       parameters is 0.

       These parameters correspond to the parameters assigned to the libopencv
       function "cvSmooth".

   oscilloscope
       2D Video Oscilloscope.

       Useful to measure spatial impulse, step responses, chroma delays, etc.

       It accepts the following parameters:

       x   Set scope center x position.

       y   Set scope center y position.

       s   Set scope size, relative to frame diagonal.

       t   Set scope tilt/rotation.

       o   Set trace opacity.

       tx  Set trace center x position.

       ty  Set trace center y position.

       tw  Set trace width, relative to width of frame.

       th  Set trace height, relative to height of frame.

       c   Set which components to trace. By default it traces first three
	   components.

       g   Draw trace grid. By default is enabled.

       st  Draw some statistics. By default is enabled.

       sc  Draw scope. By default is enabled.

       Examples

       ·   Inspect full first row of video frame.

		   oscilloscope=x=0.5:y=0:s=1

       ·   Inspect full last row of video frame.

		   oscilloscope=x=0.5:y=1:s=1

       ·   Inspect full 5th line of video frame of height 1080.

		   oscilloscope=x=0.5:y=5/1080:s=1

       ·   Inspect full last column of video frame.

		   oscilloscope=x=1:y=0.5:s=1:t=1

   overlay
       Overlay one video on top of another.

       It takes two inputs and has one output. The first input is the "main"
       video on which the second input is overlaid.

       It accepts the following parameters:

       A description of the accepted options follows.

       x
       y   Set the expression for the x and y coordinates of the overlaid
	   video on the main video. Default value is "0" for both expressions.
	   In case the expression is invalid, it is set to a huge value
	   (meaning that the overlay will not be displayed within the output
	   visible area).

       eof_action
	   See framesync.

       eval
	   Set when the expressions for x, and y are evaluated.

	   It accepts the following values:

	   init
	       only evaluate expressions once during the filter initialization
	       or when a command is processed

	   frame
	       evaluate expressions for each incoming frame

	   Default value is frame.

       shortest
	   See framesync.

       format
	   Set the format for the output video.

	   It accepts the following values:

	   yuv420
	       force YUV420 output

	   yuv422
	       force YUV422 output

	   yuv444
	       force YUV444 output

	   rgb force packed RGB output

	   gbrp
	       force planar RGB output

	   auto
	       automatically pick format

	   Default value is yuv420.

       repeatlast
	   See framesync.

       alpha
	   Set format of alpha of the overlaid video, it can be straight or
	   premultiplied. Default is straight.

       The x, and y expressions can contain the following parameters.

       main_w, W
       main_h, H
	   The main input width and height.

       overlay_w, w
       overlay_h, h
	   The overlay input width and height.

       x
       y   The computed values for x and y. They are evaluated for each new
	   frame.

       hsub
       vsub
	   horizontal and vertical chroma subsample values of the output
	   format. For example for the pixel format "yuv422p" hsub is 2 and
	   vsub is 1.

       n   the number of input frame, starting from 0

       pos the position in the file of the input frame, NAN if unknown

       t   The timestamp, expressed in seconds. It's NAN if the input
	   timestamp is unknown.

       This filter also supports the framesync options.

       Note that the n, pos, t variables are available only when evaluation is
       done per frame, and will evaluate to NAN when eval is set to init.

       Be aware that frames are taken from each input video in timestamp
       order, hence, if their initial timestamps differ, it is a good idea to
       pass the two inputs through a setpts=PTS-STARTPTS filter to have them
       begin in the same zero timestamp, as the example for the movie filter
       does.

       You can chain together more overlays but you should test the efficiency
       of such approach.

       Commands

       This filter supports the following commands:

       x
       y   Modify the x and y of the overlay input.  The command accepts the
	   same syntax of the corresponding option.

	   If the specified expression is not valid, it is kept at its current
	   value.

       Examples

       ·   Draw the overlay at 10 pixels from the bottom right corner of the
	   main video:

		   overlay=main_w-overlay_w-10:main_h-overlay_h-10

	   Using named options the example above becomes:

		   overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10

       ·   Insert a transparent PNG logo in the bottom left corner of the
	   input, using the ffmpeg tool with the "-filter_complex" option:

		   ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output

       ·   Insert 2 different transparent PNG logos (second logo on bottom
	   right corner) using the ffmpeg tool:

		   ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output

       ·   Add a transparent color layer on top of the main video; "WxH" must
	   specify the size of the main input to the overlay filter:

		   color=color=red@.3:size=WxH [over]; [in][over] overlay [out]

       ·   Play an original video and a filtered version (here with the
	   deshake filter) side by side using the ffplay tool:

		   ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'

	   The above command is the same as:

		   ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'

       ·   Make a sliding overlay appearing from the left to the right top
	   part of the screen starting since time 2:

		   overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0

       ·   Compose output by putting two input videos side to side:

		   ffmpeg -i left.avi -i right.avi -filter_complex "
		   nullsrc=size=200x100 [background];
		   [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
		   [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
		   [background][left]	    overlay=shortest=1	     [background+left];
		   [background+left][right] overlay=shortest=1:x=100 [left+right]
		   "

       ·   Mask 10-20 seconds of a video by applying the delogo filter to a
	   section

		   ffmpeg -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
		   -vf '[in]split[split_main][split_delogo];[split_delogo]trim=start=360:end=371,delogo=0:0:640:480[delogoed];[split_main][delogoed]overlay=eof_action=pass[out]'
		   masked.avi

       ·   Chain several overlays in cascade:

		   nullsrc=s=200x200 [bg];
		   testsrc=s=100x100, split=4 [in0][in1][in2][in3];
		   [in0] lutrgb=r=0, [bg]   overlay=0:0     [mid0];
		   [in1] lutrgb=g=0, [mid0] overlay=100:0   [mid1];
		   [in2] lutrgb=b=0, [mid1] overlay=0:100   [mid2];
		   [in3] null,	     [mid2] overlay=100:100 [out0]

   owdenoise
       Apply Overcomplete Wavelet denoiser.

       The filter accepts the following options:

       depth
	   Set depth.

	   Larger depth values will denoise lower frequency components more,
	   but slow down filtering.

	   Must be an int in the range 8-16, default is 8.

       luma_strength, ls
	   Set luma strength.

	   Must be a double value in the range 0-1000, default is 1.0.

       chroma_strength, cs
	   Set chroma strength.

	   Must be a double value in the range 0-1000, default is 1.0.

   pad
       Add paddings to the input image, and place the original input at the
       provided x, y coordinates.

       It accepts the following parameters:

       width, w
       height, h
	   Specify an expression for the size of the output image with the
	   paddings added. If the value for width or height is 0, the
	   corresponding input size is used for the output.

	   The width expression can reference the value set by the height
	   expression, and vice versa.

	   The default value of width and height is 0.

       x
       y   Specify the offsets to place the input image at within the padded
	   area, with respect to the top/left border of the output image.

	   The x expression can reference the value set by the y expression,
	   and vice versa.

	   The default value of x and y is 0.

	   If x or y evaluate to a negative number, they'll be changed so the
	   input image is centered on the padded area.

       color
	   Specify the color of the padded area. For the syntax of this
	   option, check the "Color" section in the ffmpeg-utils manual.

	   The default value of color is "black".

       eval
	   Specify when to evaluate  width, height, x and y expression.

	   It accepts the following values:

	   init
	       Only evaluate expressions once during the filter initialization
	       or when a command is processed.

	   frame
	       Evaluate expressions for each incoming frame.

	   Default value is init.

       aspect
	   Pad to aspect instead to a resolution.

       The value for the width, height, x, and y options are expressions
       containing the following constants:

       in_w
       in_h
	   The input video width and height.

       iw
       ih  These are the same as in_w and in_h.

       out_w
       out_h
	   The output width and height (the size of the padded area), as
	   specified by the width and height expressions.

       ow
       oh  These are the same as out_w and out_h.

       x
       y   The x and y offsets as specified by the x and y expressions, or NAN
	   if not yet specified.

       a   same as iw / ih

       sar input sample aspect ratio

       dar input display aspect ratio, it is the same as (iw / ih) * sar

       hsub
       vsub
	   The horizontal and vertical chroma subsample values. For example
	   for the pixel format "yuv422p" hsub is 2 and vsub is 1.

       Examples

       ·   Add paddings with the color "violet" to the input video. The output
	   video size is 640x480, and the top-left corner of the input video
	   is placed at column 0, row 40

		   pad=640:480:0:40:violet

	   The example above is equivalent to the following command:

		   pad=width=640:height=480:x=0:y=40:color=violet

       ·   Pad the input to get an output with dimensions increased by 3/2,
	   and put the input video at the center of the padded area:

		   pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"

       ·   Pad the input to get a squared output with size equal to the
	   maximum value between the input width and height, and put the input
	   video at the center of the padded area:

		   pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"

       ·   Pad the input to get a final w/h ratio of 16:9:

		   pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"

       ·   In case of anamorphic video, in order to set the output display
	   aspect correctly, it is necessary to use sar in the expression,
	   according to the relation:

		   (ih * X / ih) * sar = output_dar
		   X = output_dar / sar

	   Thus the previous example needs to be modified to:

		   pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"

       ·   Double the output size and put the input video in the bottom-right
	   corner of the output padded area:

		   pad="2*iw:2*ih:ow-iw:oh-ih"

   palettegen
       Generate one palette for a whole video stream.

       It accepts the following options:

       max_colors
	   Set the maximum number of colors to quantize in the palette.  Note:
	   the palette will still contain 256 colors; the unused palette
	   entries will be black.

       reserve_transparent
	   Create a palette of 255 colors maximum and reserve the last one for
	   transparency. Reserving the transparency color is useful for GIF
	   optimization.  If not set, the maximum of colors in the palette
	   will be 256. You probably want to disable this option for a
	   standalone image.  Set by default.

       transparency_color
	   Set the color that will be used as background for transparency.

       stats_mode
	   Set statistics mode.

	   It accepts the following values:

	   full
	       Compute full frame histograms.

	   diff
	       Compute histograms only for the part that differs from previous
	       frame. This might be relevant to give more importance to the
	       moving part of your input if the background is static.

	   single
	       Compute new histogram for each frame.

	   Default value is full.

       The filter also exports the frame metadata "lavfi.color_quant_ratio"
       ("nb_color_in / nb_color_out") which you can use to evaluate the degree
       of color quantization of the palette. This information is also visible
       at info logging level.

       Examples

       ·   Generate a representative palette of a given video using ffmpeg:

		   ffmpeg -i input.mkv -vf palettegen palette.png

   paletteuse
       Use a palette to downsample an input video stream.

       The filter takes two inputs: one video stream and a palette. The
       palette must be a 256 pixels image.

       It accepts the following options:

       dither
	   Select dithering mode. Available algorithms are:

	   bayer
	       Ordered 8x8 bayer dithering (deterministic)

	   heckbert
	       Dithering as defined by Paul Heckbert in 1982 (simple error
	       diffusion).  Note: this dithering is sometimes considered
	       "wrong" and is included as a reference.

	   floyd_steinberg
	       Floyd and Steingberg dithering (error diffusion)

	   sierra2
	       Frankie Sierra dithering v2 (error diffusion)

	   sierra2_4a
	       Frankie Sierra dithering v2 "Lite" (error diffusion)

	   Default is sierra2_4a.

       bayer_scale
	   When bayer dithering is selected, this option defines the scale of
	   the pattern (how much the crosshatch pattern is visible). A low
	   value means more visible pattern for less banding, and higher value
	   means less visible pattern at the cost of more banding.

	   The option must be an integer value in the range [0,5]. Default is
	   2.

       diff_mode
	   If set, define the zone to process

	   rectangle
	       Only the changing rectangle will be reprocessed. This is
	       similar to GIF cropping/offsetting compression mechanism. This
	       option can be useful for speed if only a part of the image is
	       changing, and has use cases such as limiting the scope of the
	       error diffusal dither to the rectangle that bounds the moving
	       scene (it leads to more deterministic output if the scene
	       doesn't change much, and as a result less moving noise and
	       better GIF compression).

	   Default is none.

       new Take new palette for each output frame.

       alpha_threshold
	   Sets the alpha threshold for transparency. Alpha values above this
	   threshold will be treated as completely opaque, and values below
	   this threshold will be treated as completely transparent.

	   The option must be an integer value in the range [0,255]. Default
	   is 128.

       Examples

       ·   Use a palette (generated for example with palettegen) to encode a
	   GIF using ffmpeg:

		   ffmpeg -i input.mkv -i palette.png -lavfi paletteuse output.gif

   perspective
       Correct perspective of video not recorded perpendicular to the screen.

       A description of the accepted parameters follows.

       x0
       y0
       x1
       y1
       x2
       y2
       x3
       y3  Set coordinates expression for top left, top right, bottom left and
	   bottom right corners.  Default values are "0:0:W:0:0:H:W:H" with
	   which perspective will remain unchanged.  If the "sense" option is
	   set to "source", then the specified points will be sent to the
	   corners of the destination. If the "sense" option is set to
	   "destination", then the corners of the source will be sent to the
	   specified coordinates.

	   The expressions can use the following variables:

	   W
	   H   the width and height of video frame.

	   in  Input frame count.

	   on  Output frame count.

       interpolation
	   Set interpolation for perspective correction.

	   It accepts the following values:

	   linear
	   cubic

	   Default value is linear.

       sense
	   Set interpretation of coordinate options.

	   It accepts the following values:

	   0, source
	       Send point in the source specified by the given coordinates to
	       the corners of the destination.

	   1, destination
	       Send the corners of the source to the point in the destination
	       specified by the given coordinates.

	       Default value is source.

       eval
	   Set when the expressions for coordinates x0,y0,...x3,y3 are
	   evaluated.

	   It accepts the following values:

	   init
	       only evaluate expressions once during the filter initialization
	       or when a command is processed

	   frame
	       evaluate expressions for each incoming frame

	   Default value is init.

   phase
       Delay interlaced video by one field time so that the field order
       changes.

       The intended use is to fix PAL movies that have been captured with the
       opposite field order to the film-to-video transfer.

       A description of the accepted parameters follows.

       mode
	   Set phase mode.

	   It accepts the following values:

	   t   Capture field order top-first, transfer bottom-first.  Filter
	       will delay the bottom field.

	   b   Capture field order bottom-first, transfer top-first.  Filter
	       will delay the top field.

	   p   Capture and transfer with the same field order. This mode only
	       exists for the documentation of the other options to refer to,
	       but if you actually select it, the filter will faithfully do
	       nothing.

	   a   Capture field order determined automatically by field flags,
	       transfer opposite.  Filter selects among t and b modes on a
	       frame by frame basis using field flags. If no field information
	       is available, then this works just like u.

	   u   Capture unknown or varying, transfer opposite.  Filter selects
	       among t and b on a frame by frame basis by analyzing the images
	       and selecting the alternative that produces best match between
	       the fields.

	   T   Capture top-first, transfer unknown or varying.	Filter selects
	       among t and p using image analysis.

	   B   Capture bottom-first, transfer unknown or varying.  Filter
	       selects among b and p using image analysis.

	   A   Capture determined by field flags, transfer unknown or varying.
	       Filter selects among t, b and p using field flags and image
	       analysis. If no field information is available, then this works
	       just like U. This is the default mode.

	   U   Both capture and transfer unknown or varying.  Filter selects
	       among t, b and p using image analysis only.

   pixdesctest
       Pixel format descriptor test filter, mainly useful for internal
       testing. The output video should be equal to the input video.

       For example:

	       format=monow, pixdesctest

       can be used to test the monowhite pixel format descriptor definition.

   pixscope
       Display sample values of color channels. Mainly useful for checking
       color and levels. Minimum supported resolution is 640x480.

       The filters accept the following options:

       x   Set scope X position, relative offset on X axis.

       y   Set scope Y position, relative offset on Y axis.

       w   Set scope width.

       h   Set scope height.

       o   Set window opacity. This window also holds statistics about pixel
	   area.

       wx  Set window X position, relative offset on X axis.

       wy  Set window Y position, relative offset on Y axis.

   pp
       Enable the specified chain of postprocessing subfilters using
       libpostproc. This library should be automatically selected with a GPL
       build ("--enable-gpl").	Subfilters must be separated by '/' and can be
       disabled by prepending a '-'.  Each subfilter and some options have a
       short and a long name that can be used interchangeably, i.e. dr/dering
       are the same.

       The filters accept the following options:

       subfilters
	   Set postprocessing subfilters string.

       All subfilters share common options to determine their scope:

       a/autoq
	   Honor the quality commands for this subfilter.

       c/chrom
	   Do chrominance filtering, too (default).

       y/nochrom
	   Do luminance filtering only (no chrominance).

       n/noluma
	   Do chrominance filtering only (no luminance).

       These options can be appended after the subfilter name, separated by a
       '|'.

       Available subfilters are:

       hb/hdeblock[|difference[|flatness]]
	   Horizontal deblocking filter

	   difference
	       Difference factor where higher values mean more deblocking
	       (default: 32).

	   flatness
	       Flatness threshold where lower values mean more deblocking
	       (default: 39).

       vb/vdeblock[|difference[|flatness]]
	   Vertical deblocking filter

	   difference
	       Difference factor where higher values mean more deblocking
	       (default: 32).

	   flatness
	       Flatness threshold where lower values mean more deblocking
	       (default: 39).

       ha/hadeblock[|difference[|flatness]]
	   Accurate horizontal deblocking filter

	   difference
	       Difference factor where higher values mean more deblocking
	       (default: 32).

	   flatness
	       Flatness threshold where lower values mean more deblocking
	       (default: 39).

       va/vadeblock[|difference[|flatness]]
	   Accurate vertical deblocking filter

	   difference
	       Difference factor where higher values mean more deblocking
	       (default: 32).

	   flatness
	       Flatness threshold where lower values mean more deblocking
	       (default: 39).

       The horizontal and vertical deblocking filters share the difference and
       flatness values so you cannot set different horizontal and vertical
       thresholds.

       h1/x1hdeblock
	   Experimental horizontal deblocking filter

       v1/x1vdeblock
	   Experimental vertical deblocking filter

       dr/dering
	   Deringing filter

       tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise
       reducer
	   threshold1
	       larger -> stronger filtering

	   threshold2
	       larger -> stronger filtering

	   threshold3
	       larger -> stronger filtering

       al/autolevels[:f/fullyrange], automatic brightness / contrast
       correction
	   f/fullyrange
	       Stretch luminance to "0-255".

       lb/linblenddeint
	   Linear blend deinterlacing filter that deinterlaces the given block
	   by filtering all lines with a "(1 2 1)" filter.

       li/linipoldeint
	   Linear interpolating deinterlacing filter that deinterlaces the
	   given block by linearly interpolating every second line.

       ci/cubicipoldeint
	   Cubic interpolating deinterlacing filter deinterlaces the given
	   block by cubically interpolating every second line.

       md/mediandeint
	   Median deinterlacing filter that deinterlaces the given block by
	   applying a median filter to every second line.

       fd/ffmpegdeint
	   FFmpeg deinterlacing filter that deinterlaces the given block by
	   filtering every second line with a "(-1 4 2 4 -1)" filter.

       l5/lowpass5
	   Vertically applied FIR lowpass deinterlacing filter that
	   deinterlaces the given block by filtering all lines with a "(-1 2 6
	   2 -1)" filter.

       fq/forceQuant[|quantizer]
	   Overrides the quantizer table from the input with the constant
	   quantizer you specify.

	   quantizer
	       Quantizer to use

       de/default
	   Default pp filter combination ("hb|a,vb|a,dr|a")

       fa/fast
	   Fast pp filter combination ("h1|a,v1|a,dr|a")

       ac  High quality pp filter combination ("ha|a|128|7,va|a,dr|a")

       Examples

       ·   Apply horizontal and vertical deblocking, deringing and automatic
	   brightness/contrast:

		   pp=hb/vb/dr/al

       ·   Apply default filters without brightness/contrast correction:

		   pp=de/-al

       ·   Apply default filters and temporal denoiser:

		   pp=default/tmpnoise|1|2|3

       ·   Apply deblocking on luminance only, and switch vertical deblocking
	   on or off automatically depending on available CPU time:

		   pp=hb|y/vb|a

   pp7
       Apply Postprocessing filter 7. It is variant of the spp filter, similar
       to spp = 6 with 7 point DCT, where only the center sample is used after
       IDCT.

       The filter accepts the following options:

       qp  Force a constant quantization parameter. It accepts an integer in
	   range 0 to 63. If not set, the filter will use the QP from the
	   video stream (if available).

       mode
	   Set thresholding mode. Available modes are:

	   hard
	       Set hard thresholding.

	   soft
	       Set soft thresholding (better de-ringing effect, but likely
	       blurrier).

	   medium
	       Set medium thresholding (good results, default).

   premultiply
       Apply alpha premultiply effect to input video stream using first plane
       of second stream as alpha.

       Both streams must have same dimensions and same pixel format.

       The filter accepts the following option:

       planes
	   Set which planes will be processed, unprocessed planes will be
	   copied.  By default value 0xf, all planes will be processed.

       inplace
	   Do not require 2nd input for processing, instead use alpha plane
	   from input stream.

   prewitt
       Apply prewitt operator to input video stream.

       The filter accepts the following option:

       planes
	   Set which planes will be processed, unprocessed planes will be
	   copied.  By default value 0xf, all planes will be processed.

       scale
	   Set value which will be multiplied with filtered result.

       delta
	   Set value which will be added to filtered result.

   program_opencl
       Filter video using an OpenCL program.

       source
	   OpenCL program source file.

       kernel
	   Kernel name in program.

       inputs
	   Number of inputs to the filter.  Defaults to 1.

       size, s
	   Size of output frames.  Defaults to the same as the first input.

       The program source file must contain a kernel function with the given
       name, which will be run once for each plane of the output.  Each run on
       a plane gets enqueued as a separate 2D global NDRange with one work-
       item for each pixel to be generated.  The global ID offset for each
       work-item is therefore the coordinates of a pixel in the destination
       image.

       The kernel function needs to take the following arguments:

       ·   Destination image, __write_only image2d_t.

	   This image will become the output; the kernel should write all of
	   it.

       ·   Frame index, unsigned int.

	   This is a counter starting from zero and increasing by one for each
	   frame.

       ·   Source images, __read_only image2d_t.

	   These are the most recent images on each input.  The kernel may
	   read from them to generate the output, but they can't be written
	   to.

       Example programs:

       ·   Copy the input to the output (output must be the same size as the
	   input).

		   __kernel void copy(__write_only image2d_t destination,
				      unsigned int index,
				      __read_only  image2d_t source)
		   {
		       const sampler_t sampler = CLK_NORMALIZED_COORDS_FALSE;

		       int2 location = (int2)(get_global_id(0), get_global_id(1));

		       float4 value = read_imagef(source, sampler, location);

		       write_imagef(destination, location, value);
		   }

       ·   Apply a simple transformation, rotating the input by an amount
	   increasing with the index counter.  Pixel values are linearly
	   interpolated by the sampler, and the output need not have the same
	   dimensions as the input.

		   __kernel void rotate_image(__write_only image2d_t dst,
					      unsigned int index,
					      __read_only  image2d_t src)
		   {
		       const sampler_t sampler = (CLK_NORMALIZED_COORDS_FALSE |
						  CLK_FILTER_LINEAR);

		       float angle = (float)index / 100.0f;

		       float2 dst_dim = convert_float2(get_image_dim(dst));
		       float2 src_dim = convert_float2(get_image_dim(src));

		       float2 dst_cen = dst_dim / 2.0f;
		       float2 src_cen = src_dim / 2.0f;

		       int2   dst_loc = (int2)(get_global_id(0), get_global_id(1));

		       float2 dst_pos = convert_float2(dst_loc) - dst_cen;
		       float2 src_pos = {
			   cos(angle) * dst_pos.x - sin(angle) * dst_pos.y,
			   sin(angle) * dst_pos.x + cos(angle) * dst_pos.y
		       };
		       src_pos = src_pos * src_dim / dst_dim;

		       float2 src_loc = src_pos + src_cen;

		       if (src_loc.x < 0.0f	 || src_loc.y < 0.0f ||
			   src_loc.x > src_dim.x || src_loc.y > src_dim.y)
			   write_imagef(dst, dst_loc, 0.5f);
		       else
			   write_imagef(dst, dst_loc, read_imagef(src, sampler, src_loc));
		   }

       ·   Blend two inputs together, with the amount of each input used
	   varying with the index counter.

		   __kernel void blend_images(__write_only image2d_t dst,
					      unsigned int index,
					      __read_only  image2d_t src1,
					      __read_only  image2d_t src2)
		   {
		       const sampler_t sampler = (CLK_NORMALIZED_COORDS_FALSE |
						  CLK_FILTER_LINEAR);

		       float blend = (cos((float)index / 50.0f) + 1.0f) / 2.0f;

		       int2  dst_loc = (int2)(get_global_id(0), get_global_id(1));
		       int2 src1_loc = dst_loc * get_image_dim(src1) / get_image_dim(dst);
		       int2 src2_loc = dst_loc * get_image_dim(src2) / get_image_dim(dst);

		       float4 val1 = read_imagef(src1, sampler, src1_loc);
		       float4 val2 = read_imagef(src2, sampler, src2_loc);

		       write_imagef(dst, dst_loc, val1 * blend + val2 * (1.0f - blend));
		   }

   pseudocolor
       Alter frame colors in video with pseudocolors.

       This filter accept the following options:

       c0  set pixel first component expression

       c1  set pixel second component expression

       c2  set pixel third component expression

       c3  set pixel fourth component expression, corresponds to the alpha
	   component

       i   set component to use as base for altering colors

       Each of them specifies the expression to use for computing the lookup
       table for the corresponding pixel component values.

       The expressions can contain the following constants and functions:

       w
       h   The input width and height.

       val The input value for the pixel component.

       ymin, umin, vmin, amin
	   The minimum allowed component value.

       ymax, umax, vmax, amax
	   The maximum allowed component value.

       All expressions default to "val".

       Examples

       ·   Change too high luma values to gradient:

		   pseudocolor="'if(between(val,ymax,amax),lerp(ymin,ymax,(val-ymax)/(amax-ymax)),-1):if(between(val,ymax,amax),lerp(umax,umin,(val-ymax)/(amax-ymax)),-1):if(between(val,ymax,amax),lerp(vmin,vmax,(val-ymax)/(amax-ymax)),-1):-1'"

   psnr
       Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
       Ratio) between two input videos.

       This filter takes in input two input videos, the first input is
       considered the "main" source and is passed unchanged to the output. The
       second input is used as a "reference" video for computing the PSNR.

       Both video inputs must have the same resolution and pixel format for
       this filter to work correctly. Also it assumes that both inputs have
       the same number of frames, which are compared one by one.

       The obtained average PSNR is printed through the logging system.

       The filter stores the accumulated MSE (mean squared error) of each
       frame, and at the end of the processing it is averaged across all
       frames equally, and the following formula is applied to obtain the
       PSNR:

	       PSNR = 10*log10(MAX^2/MSE)

       Where MAX is the average of the maximum values of each component of the
       image.

       The description of the accepted parameters follows.

       stats_file, f
	   If specified the filter will use the named file to save the PSNR of
	   each individual frame. When filename equals "-" the data is sent to
	   standard output.

       stats_version
	   Specifies which version of the stats file format to use. Details of
	   each format are written below.  Default value is 1.

       stats_add_max
	   Determines whether the max value is output to the stats log.
	   Default value is 0.	Requires stats_version >= 2. If this is set
	   and stats_version < 2, the filter will return an error.

       This filter also supports the framesync options.

       The file printed if stats_file is selected, contains a sequence of
       key/value pairs of the form key:value for each compared couple of
       frames.

       If a stats_version greater than 1 is specified, a header line precedes
       the list of per-frame-pair stats, with key value pairs following the
       frame format with the following parameters:

       psnr_log_version
	   The version of the log file format. Will match stats_version.

       fields
	   A comma separated list of the per-frame-pair parameters included in
	   the log.

       A description of each shown per-frame-pair parameter follows:

       n   sequential number of the input frame, starting from 1

       mse_avg
	   Mean Square Error pixel-by-pixel average difference of the compared
	   frames, averaged over all the image components.

       mse_y, mse_u, mse_v, mse_r, mse_g, mse_b, mse_a
	   Mean Square Error pixel-by-pixel average difference of the compared
	   frames for the component specified by the suffix.

       psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
	   Peak Signal to Noise ratio of the compared frames for the component
	   specified by the suffix.

       max_avg, max_y, max_u, max_v
	   Maximum allowed value for each channel, and average over all
	   channels.

       For example:

	       movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
	       [main][ref] psnr="stats_file=stats.log" [out]

       On this example the input file being processed is compared with the
       reference file ref_movie.mpg. The PSNR of each individual frame is
       stored in stats.log.

   pullup
       Pulldown reversal (inverse telecine) filter, capable of handling mixed
       hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps
       progressive content.

       The pullup filter is designed to take advantage of future context in
       making its decisions. This filter is stateless in the sense that it
       does not lock onto a pattern to follow, but it instead looks forward to
       the following fields in order to identify matches and rebuild
       progressive frames.

       To produce content with an even framerate, insert the fps filter after
       pullup, use "fps=24000/1001" if the input frame rate is 29.97fps,
       "fps=24" for 30fps and the (rare) telecined 25fps input.

       The filter accepts the following options:

       jl
       jr
       jt
       jb  These options set the amount of "junk" to ignore at the left,
	   right, top, and bottom of the image, respectively. Left and right
	   are in units of 8 pixels, while top and bottom are in units of 2
	   lines.  The default is 8 pixels on each side.

       sb  Set the strict breaks. Setting this option to 1 will reduce the
	   chances of filter generating an occasional mismatched frame, but it
	   may also cause an excessive number of frames to be dropped during
	   high motion sequences.  Conversely, setting it to -1 will make
	   filter match fields more easily.  This may help processing of video
	   where there is slight blurring between the fields, but may also
	   cause there to be interlaced frames in the output.  Default value
	   is 0.

       mp  Set the metric plane to use. It accepts the following values:

	   l   Use luma plane.

	   u   Use chroma blue plane.

	   v   Use chroma red plane.

	   This option may be set to use chroma plane instead of the default
	   luma plane for doing filter's computations. This may improve
	   accuracy on very clean source material, but more likely will
	   decrease accuracy, especially if there is chroma noise (rainbow
	   effect) or any grayscale video.  The main purpose of setting mp to
	   a chroma plane is to reduce CPU load and make pullup usable in
	   realtime on slow machines.

       For best results (without duplicated frames in the output file) it is
       necessary to change the output frame rate. For example, to inverse
       telecine NTSC input:

	       ffmpeg -i input -vf pullup -r 24000/1001 ...

   qp
       Change video quantization parameters (QP).

       The filter accepts the following option:

       qp  Set expression for quantization parameter.

       The expression is evaluated through the eval API and can contain, among
       others, the following constants:

       known
	   1 if index is not 129, 0 otherwise.

       qp  Sequential index starting from -129 to 128.

       Examples

       ·   Some equation like:

		   qp=2+2*sin(PI*qp)

   random
       Flush video frames from internal cache of frames into a random order.
       No frame is discarded.  Inspired by frei0r nervous filter.

       frames
	   Set size in number of frames of internal cache, in range from 2 to
	   512. Default is 30.

       seed
	   Set seed for random number generator, must be an integer included
	   between 0 and "UINT32_MAX". If not specified, or if explicitly set
	   to less than 0, the filter will try to use a good random seed on a
	   best effort basis.

   readeia608
       Read closed captioning (EIA-608) information from the top lines of a
       video frame.

       This filter adds frame metadata for "lavfi.readeia608.X.cc" and
       "lavfi.readeia608.X.line", where "X" is the number of the identified
       line with EIA-608 data (starting from 0). A description of each
       metadata value follows:

       lavfi.readeia608.X.cc
	   The two bytes stored as EIA-608 data (printed in hexadecimal).

       lavfi.readeia608.X.line
	   The number of the line on which the EIA-608 data was identified and
	   read.

       This filter accepts the following options:

       scan_min
	   Set the line to start scanning for EIA-608 data. Default is 0.

       scan_max
	   Set the line to end scanning for EIA-608 data. Default is 29.

       mac Set minimal acceptable amplitude change for sync codes detection.
	   Default is 0.2. Allowed range is "[0.001 - 1]".

       spw Set the ratio of width reserved for sync code detection.  Default
	   is 0.27. Allowed range is "[0.01 - 0.7]".

       mhd Set the max peaks height difference for sync code detection.
	   Default is 0.1. Allowed range is "[0.0 - 0.5]".

       mpd Set max peaks period difference for sync code detection.  Default
	   is 0.1. Allowed range is "[0.0 - 0.5]".

       msd Set the first two max start code bits differences.  Default is
	   0.02. Allowed range is "[0.0 - 0.5]".

       bhd Set the minimum ratio of bits height compared to 3rd start code
	   bit.  Default is 0.75. Allowed range is "[0.01 - 1]".

       th_w
	   Set the white color threshold. Default is 0.35. Allowed range is
	   "[0.1 - 1]".

       th_b
	   Set the black color threshold. Default is 0.15. Allowed range is
	   "[0.0 - 0.5]".

       chp Enable checking the parity bit. In the event of a parity error, the
	   filter will output 0x00 for that character. Default is false.

       Examples

       ·   Output a csv with presentation time and the first two lines of
	   identified EIA-608 captioning data.

		   ffprobe -f lavfi -i movie=captioned_video.mov,readeia608 -show_entries frame=pkt_pts_time:frame_tags=lavfi.readeia608.0.cc,lavfi.readeia608.1.cc -of csv

   readvitc
       Read vertical interval timecode (VITC) information from the top lines
       of a video frame.

       The filter adds frame metadata key "lavfi.readvitc.tc_str" with the
       timecode value, if a valid timecode has been detected. Further metadata
       key "lavfi.readvitc.found" is set to 0/1 depending on whether timecode
       data has been found or not.

       This filter accepts the following options:

       scan_max
	   Set the maximum number of lines to scan for VITC data. If the value
	   is set to "-1" the full video frame is scanned. Default is 45.

       thr_b
	   Set the luma threshold for black. Accepts float numbers in the
	   range [0.0,1.0], default value is 0.2. The value must be equal or
	   less than "thr_w".

       thr_w
	   Set the luma threshold for white. Accepts float numbers in the
	   range [0.0,1.0], default value is 0.6. The value must be equal or
	   greater than "thr_b".

       Examples

       ·   Detect and draw VITC data onto the video frame; if no valid VITC is
	   detected, draw "--:--:--:--" as a placeholder:

		   ffmpeg -i input.avi -filter:v 'readvitc,drawtext=fontfile=FreeMono.ttf:text=%{metadata\\:lavfi.readvitc.tc_str\\:--\\\\\\:--\\\\\\:--\\\\\\:--}:x=(w-tw)/2:y=400-ascent'

   remap
       Remap pixels using 2nd: Xmap and 3rd: Ymap input video stream.

       Destination pixel at position (X, Y) will be picked from source (x, y)
       position where x = Xmap(X, Y) and y = Ymap(X, Y). If mapping values are
       out of range, zero value for pixel will be used for destination pixel.

       Xmap and Ymap input video streams must be of same dimensions. Output
       video stream will have Xmap/Ymap video stream dimensions.  Xmap and
       Ymap input video streams are 16bit depth, single channel.

   removegrain
       The removegrain filter is a spatial denoiser for progressive video.

       m0  Set mode for the first plane.

       m1  Set mode for the second plane.

       m2  Set mode for the third plane.

       m3  Set mode for the fourth plane.

       Range of mode is from 0 to 24. Description of each mode follows:

       0   Leave input plane unchanged. Default.

       1   Clips the pixel with the minimum and maximum of the 8 neighbour
	   pixels.

       2   Clips the pixel with the second minimum and maximum of the 8
	   neighbour pixels.

       3   Clips the pixel with the third minimum and maximum of the 8
	   neighbour pixels.

       4   Clips the pixel with the fourth minimum and maximum of the 8
	   neighbour pixels.  This is equivalent to a median filter.

       5   Line-sensitive clipping giving the minimal change.

       6   Line-sensitive clipping, intermediate.

       7   Line-sensitive clipping, intermediate.

       8   Line-sensitive clipping, intermediate.

       9   Line-sensitive clipping on a line where the neighbours pixels are
	   the closest.

       10  Replaces the target pixel with the closest neighbour.

       11  [1 2 1] horizontal and vertical kernel blur.

       12  Same as mode 11.

       13  Bob mode, interpolates top field from the line where the neighbours
	   pixels are the closest.

       14  Bob mode, interpolates bottom field from the line where the
	   neighbours pixels are the closest.

       15  Bob mode, interpolates top field. Same as 13 but with a more
	   complicated interpolation formula.

       16  Bob mode, interpolates bottom field. Same as 14 but with a more
	   complicated interpolation formula.

       17  Clips the pixel with the minimum and maximum of respectively the
	   maximum and minimum of each pair of opposite neighbour pixels.

       18  Line-sensitive clipping using opposite neighbours whose greatest
	   distance from the current pixel is minimal.

       19  Replaces the pixel with the average of its 8 neighbours.

       20  Averages the 9 pixels ([1 1 1] horizontal and vertical blur).

       21  Clips pixels using the averages of opposite neighbour.

       22  Same as mode 21 but simpler and faster.

       23  Small edge and halo removal, but reputed useless.

       24  Similar as 23.

   removelogo
       Suppress a TV station logo, using an image file to determine which
       pixels comprise the logo. It works by filling in the pixels that
       comprise the logo with neighboring pixels.

       The filter accepts the following options:

       filename, f
	   Set the filter bitmap file, which can be any image format supported
	   by libavformat. The width and height of the image file must match
	   those of the video stream being processed.

       Pixels in the provided bitmap image with a value of zero are not
       considered part of the logo, non-zero pixels are considered part of the
       logo. If you use white (255) for the logo and black (0) for the rest,
       you will be safe. For making the filter bitmap, it is recommended to
       take a screen capture of a black frame with the logo visible, and then
       using a threshold filter followed by the erode filter once or twice.

       If needed, little splotches can be fixed manually. Remember that if
       logo pixels are not covered, the filter quality will be much reduced.
       Marking too many pixels as part of the logo does not hurt as much, but
       it will increase the amount of blurring needed to cover over the image
       and will destroy more information than necessary, and extra pixels will
       slow things down on a large logo.

   repeatfields
       This filter uses the repeat_field flag from the Video ES headers and
       hard repeats fields based on its value.

   reverse
       Reverse a video clip.

       Warning: This filter requires memory to buffer the entire clip, so
       trimming is suggested.

       Examples

       ·   Take the first 5 seconds of a clip, and reverse it.

		   trim=end=5,reverse

   roberts
       Apply roberts cross operator to input video stream.

       The filter accepts the following option:

       planes
	   Set which planes will be processed, unprocessed planes will be
	   copied.  By default value 0xf, all planes will be processed.

       scale
	   Set value which will be multiplied with filtered result.

       delta
	   Set value which will be added to filtered result.

   rotate
       Rotate video by an arbitrary angle expressed in radians.

       The filter accepts the following options:

       A description of the optional parameters follows.

       angle, a
	   Set an expression for the angle by which to rotate the input video
	   clockwise, expressed as a number of radians. A negative value will
	   result in a counter-clockwise rotation. By default it is set to
	   "0".

	   This expression is evaluated for each frame.

       out_w, ow
	   Set the output width expression, default value is "iw".  This
	   expression is evaluated just once during configuration.

       out_h, oh
	   Set the output height expression, default value is "ih".  This
	   expression is evaluated just once during configuration.

       bilinear
	   Enable bilinear interpolation if set to 1, a value of 0 disables
	   it. Default value is 1.

       fillcolor, c
	   Set the color used to fill the output area not covered by the
	   rotated image. For the general syntax of this option, check the
	   "Color" section in the ffmpeg-utils manual.	If the special value
	   "none" is selected then no background is printed (useful for
	   example if the background is never shown).

	   Default value is "black".

       The expressions for the angle and the output size can contain the
       following constants and functions:

       n   sequential number of the input frame, starting from 0. It is always
	   NAN before the first frame is filtered.

       t   time in seconds of the input frame, it is set to 0 when the filter
	   is configured. It is always NAN before the first frame is filtered.

       hsub
       vsub
	   horizontal and vertical chroma subsample values. For example for
	   the pixel format "yuv422p" hsub is 2 and vsub is 1.

       in_w, iw
       in_h, ih
	   the input video width and height

       out_w, ow
       out_h, oh
	   the output width and height, that is the size of the padded area as
	   specified by the width and height expressions

       rotw(a)
       roth(a)
	   the minimal width/height required for completely containing the
	   input video rotated by a radians.

	   These are only available when computing the out_w and out_h
	   expressions.

       Examples

       ·   Rotate the input by PI/6 radians clockwise:

		   rotate=PI/6

       ·   Rotate the input by PI/6 radians counter-clockwise:

		   rotate=-PI/6

       ·   Rotate the input by 45 degrees clockwise:

		   rotate=45*PI/180

       ·   Apply a constant rotation with period T, starting from an angle of
	   PI/3:

		   rotate=PI/3+2*PI*t/T

       ·   Make the input video rotation oscillating with a period of T
	   seconds and an amplitude of A radians:

		   rotate=A*sin(2*PI/T*t)

       ·   Rotate the video, output size is chosen so that the whole rotating
	   input video is always completely contained in the output:

		   rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'

       ·   Rotate the video, reduce the output size so that no background is
	   ever shown:

		   rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none

       Commands

       The filter supports the following commands:

       a, angle
	   Set the angle expression.  The command accepts the same syntax of
	   the corresponding option.

	   If the specified expression is not valid, it is kept at its current
	   value.

   sab
       Apply Shape Adaptive Blur.

       The filter accepts the following options:

       luma_radius, lr
	   Set luma blur filter strength, must be a value in range 0.1-4.0,
	   default value is 1.0. A greater value will result in a more blurred
	   image, and in slower processing.

       luma_pre_filter_radius, lpfr
	   Set luma pre-filter radius, must be a value in the 0.1-2.0 range,
	   default value is 1.0.

       luma_strength, ls
	   Set luma maximum difference between pixels to still be considered,
	   must be a value in the 0.1-100.0 range, default value is 1.0.

       chroma_radius, cr
	   Set chroma blur filter strength, must be a value in range -0.9-4.0.
	   A greater value will result in a more blurred image, and in slower
	   processing.

       chroma_pre_filter_radius, cpfr
	   Set chroma pre-filter radius, must be a value in the -0.9-2.0
	   range.

       chroma_strength, cs
	   Set chroma maximum difference between pixels to still be
	   considered, must be a value in the -0.9-100.0 range.

       Each chroma option value, if not explicitly specified, is set to the
       corresponding luma option value.

   scale
       Scale (resize) the input video, using the libswscale library.

       The scale filter forces the output display aspect ratio to be the same
       of the input, by changing the output sample aspect ratio.

       If the input image format is different from the format requested by the
       next filter, the scale filter will convert the input to the requested
       format.

       Options

       The filter accepts the following options, or any of the options
       supported by the libswscale scaler.

       See the ffmpeg-scaler manual for the complete list of scaler options.

       width, w
       height, h
	   Set the output video dimension expression. Default value is the
	   input dimension.

	   If the width or w value is 0, the input width is used for the
	   output. If the height or h value is 0, the input height is used for
	   the output.

	   If one and only one of the values is -n with n >= 1, the scale
	   filter will use a value that maintains the aspect ratio of the
	   input image, calculated from the other specified dimension. After
	   that it will, however, make sure that the calculated dimension is
	   divisible by n and adjust the value if necessary.

	   If both values are -n with n >= 1, the behavior will be identical
	   to both values being set to 0 as previously detailed.

	   See below for the list of accepted constants for use in the
	   dimension expression.

       eval
	   Specify when to evaluate width and height expression. It accepts
	   the following values:

	   init
	       Only evaluate expressions once during the filter initialization
	       or when a command is processed.

	   frame
	       Evaluate expressions for each incoming frame.

	   Default value is init.

       interl
	   Set the interlacing mode. It accepts the following values:

	   1   Force interlaced aware scaling.

	   0   Do not apply interlaced scaling.

	   -1  Select interlaced aware scaling depending on whether the source
	       frames are flagged as interlaced or not.

	   Default value is 0.

       flags
	   Set libswscale scaling flags. See the ffmpeg-scaler manual for the
	   complete list of values. If not explicitly specified the filter
	   applies the default flags.

       param0, param1
	   Set libswscale input parameters for scaling algorithms that need
	   them. See the ffmpeg-scaler manual for the complete documentation.
	   If not explicitly specified the filter applies empty parameters.

       size, s
	   Set the video size. For the syntax of this option, check the "Video
	   size" section in the ffmpeg-utils manual.

       in_color_matrix
       out_color_matrix
	   Set in/output YCbCr color space type.

	   This allows the autodetected value to be overridden as well as
	   allows forcing a specific value used for the output and encoder.

	   If not specified, the color space type depends on the pixel format.

	   Possible values:

	   auto
	       Choose automatically.

	   bt709
	       Format conforming to International Telecommunication Union
	       (ITU) Recommendation BT.709.

	   fcc Set color space conforming to the United States Federal
	       Communications Commission (FCC) Code of Federal Regulations
	       (CFR) Title 47 (2003) 73.682 (a).

	   bt601
	       Set color space conforming to:

	       ·   ITU Radiocommunication Sector (ITU-R) Recommendation BT.601

	       ·   ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G

	       ·   Society of Motion Picture and Television Engineers (SMPTE)
		   ST 170:2004

	   smpte240m
	       Set color space conforming to SMPTE ST 240:1999.

       in_range
       out_range
	   Set in/output YCbCr sample range.

	   This allows the autodetected value to be overridden as well as
	   allows forcing a specific value used for the output and encoder. If
	   not specified, the range depends on the pixel format. Possible
	   values:

	   auto/unknown
	       Choose automatically.

	   jpeg/full/pc
	       Set full range (0-255 in case of 8-bit luma).

	   mpeg/limited/tv
	       Set "MPEG" range (16-235 in case of 8-bit luma).

       force_original_aspect_ratio
	   Enable decreasing or increasing output video width or height if
	   necessary to keep the original aspect ratio. Possible values:

	   disable
	       Scale the video as specified and disable this feature.

	   decrease
	       The output video dimensions will automatically be decreased if
	       needed.

	   increase
	       The output video dimensions will automatically be increased if
	       needed.

	   One useful instance of this option is that when you know a specific
	   device's maximum allowed resolution, you can use this to limit the
	   output video to that, while retaining the aspect ratio. For
	   example, device A allows 1280x720 playback, and your video is
	   1920x800. Using this option (set it to decrease) and specifying
	   1280x720 to the command line makes the output 1280x533.

	   Please note that this is a different thing than specifying -1 for w
	   or h, you still need to specify the output resolution for this
	   option to work.

       The values of the w and h options are expressions containing the
       following constants:

       in_w
       in_h
	   The input width and height

       iw
       ih  These are the same as in_w and in_h.

       out_w
       out_h
	   The output (scaled) width and height

       ow
       oh  These are the same as out_w and out_h

       a   The same as iw / ih

       sar input sample aspect ratio

       dar The input display aspect ratio. Calculated from "(iw / ih) * sar".

       hsub
       vsub
	   horizontal and vertical input chroma subsample values. For example
	   for the pixel format "yuv422p" hsub is 2 and vsub is 1.

       ohsub
       ovsub
	   horizontal and vertical output chroma subsample values. For example
	   for the pixel format "yuv422p" hsub is 2 and vsub is 1.

       Examples

       ·   Scale the input video to a size of 200x100

		   scale=w=200:h=100

	   This is equivalent to:

		   scale=200:100

	   or:

		   scale=200x100

       ·   Specify a size abbreviation for the output size:

		   scale=qcif

	   which can also be written as:

		   scale=size=qcif

       ·   Scale the input to 2x:

		   scale=w=2*iw:h=2*ih

       ·   The above is the same as:

		   scale=2*in_w:2*in_h

       ·   Scale the input to 2x with forced interlaced scaling:

		   scale=2*iw:2*ih:interl=1

       ·   Scale the input to half size:

		   scale=w=iw/2:h=ih/2

       ·   Increase the width, and set the height to the same size:

		   scale=3/2*iw:ow

       ·   Seek Greek harmony:

		   scale=iw:1/PHI*iw
		   scale=ih*PHI:ih

       ·   Increase the height, and set the width to 3/2 of the height:

		   scale=w=3/2*oh:h=3/5*ih

       ·   Increase the size, making the size a multiple of the chroma
	   subsample values:

		   scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"

       ·   Increase the width to a maximum of 500 pixels, keeping the same
	   aspect ratio as the input:

		   scale=w='min(500\, iw*3/2):h=-1'

       ·   Make pixels square by combining scale and setsar:

		   scale='trunc(ih*dar):ih',setsar=1/1

       ·   Make pixels square by combining scale and setsar, making sure the
	   resulting resolution is even (required by some codecs):

		   scale='trunc(ih*dar/2)*2:trunc(ih/2)*2',setsar=1/1

       Commands

       This filter supports the following commands:

       width, w
       height, h
	   Set the output video dimension expression.  The command accepts the
	   same syntax of the corresponding option.

	   If the specified expression is not valid, it is kept at its current
	   value.

   scale_npp
       Use the NVIDIA Performance Primitives (libnpp) to perform scaling
       and/or pixel format conversion on CUDA video frames. Setting the output
       width and height works in the same way as for the scale filter.

       The following additional options are accepted:

       format
	   The pixel format of the output CUDA frames. If set to the string
	   "same" (the default), the input format will be kept. Note that
	   automatic format negotiation and conversion is not yet supported
	   for hardware frames

       interp_algo
	   The interpolation algorithm used for resizing. One of the
	   following:

	   nn  Nearest neighbour.

	   linear
	   cubic
	   cubic2p_bspline
	       2-parameter cubic (B=1, C=0)

	   cubic2p_catmullrom
	       2-parameter cubic (B=0, C=1/2)

	   cubic2p_b05c03
	       2-parameter cubic (B=1/2, C=3/10)

	   super
	       Supersampling

	   lanczos

   scale2ref
       Scale (resize) the input video, based on a reference video.

       See the scale filter for available options, scale2ref supports the same
       but uses the reference video instead of the main input as basis.
       scale2ref also supports the following additional constants for the w
       and h options:

       main_w
       main_h
	   The main input video's width and height

       main_a
	   The same as main_w / main_h

       main_sar
	   The main input video's sample aspect ratio

       main_dar, mdar
	   The main input video's display aspect ratio. Calculated from
	   "(main_w / main_h) * main_sar".

       main_hsub
       main_vsub
	   The main input video's horizontal and vertical chroma subsample
	   values.  For example for the pixel format "yuv422p" hsub is 2 and
	   vsub is 1.

       Examples

       ·   Scale a subtitle stream (b) to match the main video (a) in size
	   before overlaying

		   'scale2ref[b][a];[a][b]overlay'

   selectivecolor
       Adjust cyan, magenta, yellow and black (CMYK) to certain ranges of
       colors (such as "reds", "yellows", "greens", "cyans", ...). The
       adjustment range is defined by the "purity" of the color (that is, how
       saturated it already is).

       This filter is similar to the Adobe Photoshop Selective Color tool.

       The filter accepts the following options:

       correction_method
	   Select color correction method.

	   Available values are:

	   absolute
	       Specified adjustments are applied "as-is" (added/subtracted to
	       original pixel component value).

	   relative
	       Specified adjustments are relative to the original component
	       value.

	   Default is "absolute".

       reds
	   Adjustments for red pixels (pixels where the red component is the
	   maximum)

       yellows
	   Adjustments for yellow pixels (pixels where the blue component is
	   the minimum)

       greens
	   Adjustments for green pixels (pixels where the green component is
	   the maximum)

       cyans
	   Adjustments for cyan pixels (pixels where the red component is the
	   minimum)

       blues
	   Adjustments for blue pixels (pixels where the blue component is the
	   maximum)

       magentas
	   Adjustments for magenta pixels (pixels where the green component is
	   the minimum)

       whites
	   Adjustments for white pixels (pixels where all components are
	   greater than 128)

       neutrals
	   Adjustments for all pixels except pure black and pure white

       blacks
	   Adjustments for black pixels (pixels where all components are
	   lesser than 128)

       psfile
	   Specify a Photoshop selective color file (".asv") to import the
	   settings from.

       All the adjustment settings (reds, yellows, ...) accept up to 4 space
       separated floating point adjustment values in the [-1,1] range,
       respectively to adjust the amount of cyan, magenta, yellow and black
       for the pixels of its range.

       Examples

       ·   Increase cyan by 50% and reduce yellow by 33% in every green areas,
	   and increase magenta by 27% in blue areas:

		   selectivecolor=greens=.5 0 -.33 0:blues=0 .27

       ·   Use a Photoshop selective color preset:

		   selectivecolor=psfile=MySelectiveColorPresets/Misty.asv

   separatefields
       The "separatefields" takes a frame-based video input and splits each
       frame into its components fields, producing a new half height clip with
       twice the frame rate and twice the frame count.

       This filter use field-dominance information in frame to decide which of
       each pair of fields to place first in the output.  If it gets it wrong
       use setfield filter before "separatefields" filter.

   setdar, setsar
       The "setdar" filter sets the Display Aspect Ratio for the filter output
       video.

       This is done by changing the specified Sample (aka Pixel) Aspect Ratio,
       according to the following equation:

	       <DAR> = <HORIZONTAL_RESOLUTION> / <VERTICAL_RESOLUTION> * <SAR>

       Keep in mind that the "setdar" filter does not modify the pixel
       dimensions of the video frame. Also, the display aspect ratio set by
       this filter may be changed by later filters in the filterchain, e.g. in
       case of scaling or if another "setdar" or a "setsar" filter is applied.

       The "setsar" filter sets the Sample (aka Pixel) Aspect Ratio for the
       filter output video.

       Note that as a consequence of the application of this filter, the
       output display aspect ratio will change according to the equation
       above.

       Keep in mind that the sample aspect ratio set by the "setsar" filter
       may be changed by later filters in the filterchain, e.g. if another
       "setsar" or a "setdar" filter is applied.

       It accepts the following parameters:

       r, ratio, dar ("setdar" only), sar ("setsar" only)
	   Set the aspect ratio used by the filter.

	   The parameter can be a floating point number string, an expression,
	   or a string of the form num:den, where num and den are the
	   numerator and denominator of the aspect ratio. If the parameter is
	   not specified, it is assumed the value "0".	In case the form
	   "num:den" is used, the ":" character should be escaped.

       max Set the maximum integer value to use for expressing numerator and
	   denominator when reducing the expressed aspect ratio to a rational.
	   Default value is 100.

       The parameter sar is an expression containing the following constants:

       E, PI, PHI
	   These are approximated values for the mathematical constants e
	   (Euler's number), pi (Greek pi), and phi (the golden ratio).

       w, h
	   The input width and height.

       a   These are the same as w / h.

       sar The input sample aspect ratio.

       dar The input display aspect ratio. It is the same as (w / h) * sar.

       hsub, vsub
	   Horizontal and vertical chroma subsample values. For example, for
	   the pixel format "yuv422p" hsub is 2 and vsub is 1.

       Examples

       ·   To change the display aspect ratio to 16:9, specify one of the
	   following:

		   setdar=dar=1.77777
		   setdar=dar=16/9

       ·   To change the sample aspect ratio to 10:11, specify:

		   setsar=sar=10/11

       ·   To set a display aspect ratio of 16:9, and specify a maximum
	   integer value of 1000 in the aspect ratio reduction, use the
	   command:

		   setdar=ratio=16/9:max=1000

   setfield
       Force field for the output video frame.

       The "setfield" filter marks the interlace type field for the output
       frames. It does not change the input frame, but only sets the
       corresponding property, which affects how the frame is treated by
       following filters (e.g. "fieldorder" or "yadif").

       The filter accepts the following options:

       mode
	   Available values are:

	   auto
	       Keep the same field property.

	   bff Mark the frame as bottom-field-first.

	   tff Mark the frame as top-field-first.

	   prog
	       Mark the frame as progressive.

   showinfo
       Show a line containing various information for each input video frame.
       The input video is not modified.

       The shown line contains a sequence of key/value pairs of the form
       key:value.

       The following values are shown in the output:

       n   The (sequential) number of the input frame, starting from 0.

       pts The Presentation TimeStamp of the input frame, expressed as a
	   number of time base units. The time base unit depends on the filter
	   input pad.

       pts_time
	   The Presentation TimeStamp of the input frame, expressed as a
	   number of seconds.

       pos The position of the frame in the input stream, or -1 if this
	   information is unavailable and/or meaningless (for example in case
	   of synthetic video).

       fmt The pixel format name.

       sar The sample aspect ratio of the input frame, expressed in the form
	   num/den.

       s   The size of the input frame. For the syntax of this option, check
	   the "Video size" section in the ffmpeg-utils manual.

       i   The type of interlaced mode ("P" for "progressive", "T" for top
	   field first, "B" for bottom field first).

       iskey
	   This is 1 if the frame is a key frame, 0 otherwise.

       type
	   The picture type of the input frame ("I" for an I-frame, "P" for a
	   P-frame, "B" for a B-frame, or "?" for an unknown type).  Also
	   refer to the documentation of the "AVPictureType" enum and of the
	   "av_get_picture_type_char" function defined in libavutil/avutil.h.

       checksum
	   The Adler-32 checksum (printed in hexadecimal) of all the planes of
	   the input frame.

       plane_checksum
	   The Adler-32 checksum (printed in hexadecimal) of each plane of the
	   input frame, expressed in the form "[c0 c1 c2 c3]".

   showpalette
       Displays the 256 colors palette of each frame. This filter is only
       relevant for pal8 pixel format frames.

       It accepts the following option:

       s   Set the size of the box used to represent one palette color entry.
	   Default is 30 (for a "30x30" pixel box).

   shuffleframes
       Reorder and/or duplicate and/or drop video frames.

       It accepts the following parameters:

       mapping
	   Set the destination indexes of input frames.  This is space or '|'
	   separated list of indexes that maps input frames to output frames.
	   Number of indexes also sets maximal value that each index may have.
	   '-1' index have special meaning and that is to drop frame.

       The first frame has the index 0. The default is to keep the input
       unchanged.

       Examples

       ·   Swap second and third frame of every three frames of the input:

		   ffmpeg -i INPUT -vf "shuffleframes=0 2 1" OUTPUT

       ·   Swap 10th and 1st frame of every ten frames of the input:

		   ffmpeg -i INPUT -vf "shuffleframes=9 1 2 3 4 5 6 7 8 0" OUTPUT

   shuffleplanes
       Reorder and/or duplicate video planes.

       It accepts the following parameters:

       map0
	   The index of the input plane to be used as the first output plane.

       map1
	   The index of the input plane to be used as the second output plane.

       map2
	   The index of the input plane to be used as the third output plane.

       map3
	   The index of the input plane to be used as the fourth output plane.

       The first plane has the index 0. The default is to keep the input
       unchanged.

       Examples

       ·   Swap the second and third planes of the input:

		   ffmpeg -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT

   signalstats
       Evaluate various visual metrics that assist in determining issues
       associated with the digitization of analog video media.

       By default the filter will log these metadata values:

       YMIN
	   Display the minimal Y value contained within the input frame.
	   Expressed in range of [0-255].

       YLOW
	   Display the Y value at the 10% percentile within the input frame.
	   Expressed in range of [0-255].

       YAVG
	   Display the average Y value within the input frame. Expressed in
	   range of [0-255].

       YHIGH
	   Display the Y value at the 90% percentile within the input frame.
	   Expressed in range of [0-255].

       YMAX
	   Display the maximum Y value contained within the input frame.
	   Expressed in range of [0-255].

       UMIN
	   Display the minimal U value contained within the input frame.
	   Expressed in range of [0-255].

       ULOW
	   Display the U value at the 10% percentile within the input frame.
	   Expressed in range of [0-255].

       UAVG
	   Display the average U value within the input frame. Expressed in
	   range of [0-255].

       UHIGH
	   Display the U value at the 90% percentile within the input frame.
	   Expressed in range of [0-255].

       UMAX
	   Display the maximum U value contained within the input frame.
	   Expressed in range of [0-255].

       VMIN
	   Display the minimal V value contained within the input frame.
	   Expressed in range of [0-255].

       VLOW
	   Display the V value at the 10% percentile within the input frame.
	   Expressed in range of [0-255].

       VAVG
	   Display the average V value within the input frame. Expressed in
	   range of [0-255].

       VHIGH
	   Display the V value at the 90% percentile within the input frame.
	   Expressed in range of [0-255].

       VMAX
	   Display the maximum V value contained within the input frame.
	   Expressed in range of [0-255].

       SATMIN
	   Display the minimal saturation value contained within the input
	   frame.  Expressed in range of [0-~181.02].

       SATLOW
	   Display the saturation value at the 10% percentile within the input
	   frame.  Expressed in range of [0-~181.02].

       SATAVG
	   Display the average saturation value within the input frame.
	   Expressed in range of [0-~181.02].

       SATHIGH
	   Display the saturation value at the 90% percentile within the input
	   frame.  Expressed in range of [0-~181.02].

       SATMAX
	   Display the maximum saturation value contained within the input
	   frame.  Expressed in range of [0-~181.02].

       HUEMED
	   Display the median value for hue within the input frame. Expressed
	   in range of [0-360].

       HUEAVG
	   Display the average value for hue within the input frame. Expressed
	   in range of [0-360].

       YDIF
	   Display the average of sample value difference between all values
	   of the Y plane in the current frame and corresponding values of the
	   previous input frame.  Expressed in range of [0-255].

       UDIF
	   Display the average of sample value difference between all values
	   of the U plane in the current frame and corresponding values of the
	   previous input frame.  Expressed in range of [0-255].

       VDIF
	   Display the average of sample value difference between all values
	   of the V plane in the current frame and corresponding values of the
	   previous input frame.  Expressed in range of [0-255].

       YBITDEPTH
	   Display bit depth of Y plane in current frame.  Expressed in range
	   of [0-16].

       UBITDEPTH
	   Display bit depth of U plane in current frame.  Expressed in range
	   of [0-16].

       VBITDEPTH
	   Display bit depth of V plane in current frame.  Expressed in range
	   of [0-16].

       The filter accepts the following options:

       stat
       out stat specify an additional form of image analysis.  out output
	   video with the specified type of pixel highlighted.

	   Both options accept the following values:

	   tout
	       Identify temporal outliers pixels. A temporal outlier is a
	       pixel unlike the neighboring pixels of the same field. Examples
	       of temporal outliers include the results of video dropouts,
	       head clogs, or tape tracking issues.

	   vrep
	       Identify vertical line repetition. Vertical line repetition
	       includes similar rows of pixels within a frame. In born-digital
	       video vertical line repetition is common, but this pattern is
	       uncommon in video digitized from an analog source. When it
	       occurs in video that results from the digitization of an analog
	       source it can indicate concealment from a dropout compensator.

	   brng
	       Identify pixels that fall outside of legal broadcast range.

       color, c
	   Set the highlight color for the out option. The default color is
	   yellow.

       Examples

       ·   Output data of various video metrics:

		   ffprobe -f lavfi movie=example.mov,signalstats="stat=tout+vrep+brng" -show_frames

       ·   Output specific data about the minimum and maximum values of the Y
	   plane per frame:

		   ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.signalstats.YMAX,lavfi.signalstats.YMIN

       ·   Playback video while highlighting pixels that are outside of
	   broadcast range in red.

		   ffplay example.mov -vf signalstats="out=brng:color=red"

       ·   Playback video with signalstats metadata drawn over the frame.

		   ffplay example.mov -vf signalstats=stat=brng+vrep+tout,drawtext=fontfile=FreeSerif.ttf:textfile=signalstat_drawtext.txt

	   The contents of signalstat_drawtext.txt used in the command are:

		   time %{pts:hms}
		   Y (%{metadata:lavfi.signalstats.YMIN}-%{metadata:lavfi.signalstats.YMAX})
		   U (%{metadata:lavfi.signalstats.UMIN}-%{metadata:lavfi.signalstats.UMAX})
		   V (%{metadata:lavfi.signalstats.VMIN}-%{metadata:lavfi.signalstats.VMAX})
		   saturation maximum: %{metadata:lavfi.signalstats.SATMAX}

   signature
       Calculates the MPEG-7 Video Signature. The filter can handle more than
       one input. In this case the matching between the inputs can be
       calculated additionally.  The filter always passes through the first
       input. The signature of each stream can be written into a file.

       It accepts the following options:

       detectmode
	   Enable or disable the matching process.

	   Available values are:

	   off Disable the calculation of a matching (default).

	   full
	       Calculate the matching for the whole video and output whether
	       the whole video matches or only parts.

	   fast
	       Calculate only until a matching is found or the video ends.
	       Should be faster in some cases.

       nb_inputs
	   Set the number of inputs. The option value must be a non negative
	   integer.  Default value is 1.

       filename
	   Set the path to which the output is written. If there is more than
	   one input, the path must be a prototype, i.e. must contain %d or
	   %0nd (where n is a positive integer), that will be replaced with
	   the input number. If no filename is specified, no output will be
	   written. This is the default.

       format
	   Choose the output format.

	   Available values are:

	   binary
	       Use the specified binary representation (default).

	   xml Use the specified xml representation.

       th_d
	   Set threshold to detect one word as similar. The option value must
	   be an integer greater than zero. The default value is 9000.

       th_dc
	   Set threshold to detect all words as similar. The option value must
	   be an integer greater than zero. The default value is 60000.

       th_xh
	   Set threshold to detect frames as similar. The option value must be
	   an integer greater than zero. The default value is 116.

       th_di
	   Set the minimum length of a sequence in frames to recognize it as
	   matching sequence. The option value must be a non negative integer
	   value.  The default value is 0.

       th_it
	   Set the minimum relation, that matching frames to all frames must
	   have.  The option value must be a double value between 0 and 1. The
	   default value is 0.5.

       Examples

       ·   To calculate the signature of an input video and store it in
	   signature.bin:

		   ffmpeg -i input.mkv -vf signature=filename=signature.bin -map 0:v -f null -

       ·   To detect whether two videos match and store the signatures in XML
	   format in signature0.xml and signature1.xml:

		   ffmpeg -i input1.mkv -i input2.mkv -filter_complex "[0:v][1:v] signature=nb_inputs=2:detectmode=full:format=xml:filename=signature%d.xml" -map :v -f null -

   smartblur
       Blur the input video without impacting the outlines.

       It accepts the following options:

       luma_radius, lr
	   Set the luma radius. The option value must be a float number in the
	   range [0.1,5.0] that specifies the variance of the gaussian filter
	   used to blur the image (slower if larger). Default value is 1.0.

       luma_strength, ls
	   Set the luma strength. The option value must be a float number in
	   the range [-1.0,1.0] that configures the blurring. A value included
	   in [0.0,1.0] will blur the image whereas a value included in
	   [-1.0,0.0] will sharpen the image. Default value is 1.0.

       luma_threshold, lt
	   Set the luma threshold used as a coefficient to determine whether a
	   pixel should be blurred or not. The option value must be an integer
	   in the range [-30,30]. A value of 0 will filter all the image, a
	   value included in [0,30] will filter flat areas and a value
	   included in [-30,0] will filter edges. Default value is 0.

       chroma_radius, cr
	   Set the chroma radius. The option value must be a float number in
	   the range [0.1,5.0] that specifies the variance of the gaussian
	   filter used to blur the image (slower if larger). Default value is
	   luma_radius.

       chroma_strength, cs
	   Set the chroma strength. The option value must be a float number in
	   the range [-1.0,1.0] that configures the blurring. A value included
	   in [0.0,1.0] will blur the image whereas a value included in
	   [-1.0,0.0] will sharpen the image. Default value is luma_strength.

       chroma_threshold, ct
	   Set the chroma threshold used as a coefficient to determine whether
	   a pixel should be blurred or not. The option value must be an
	   integer in the range [-30,30]. A value of 0 will filter all the
	   image, a value included in [0,30] will filter flat areas and a
	   value included in [-30,0] will filter edges. Default value is
	   luma_threshold.

       If a chroma option is not explicitly set, the corresponding luma value
       is set.

   ssim
       Obtain the SSIM (Structural SImilarity Metric) between two input
       videos.

       This filter takes in input two input videos, the first input is
       considered the "main" source and is passed unchanged to the output. The
       second input is used as a "reference" video for computing the SSIM.

       Both video inputs must have the same resolution and pixel format for
       this filter to work correctly. Also it assumes that both inputs have
       the same number of frames, which are compared one by one.

       The filter stores the calculated SSIM of each frame.

       The description of the accepted parameters follows.

       stats_file, f
	   If specified the filter will use the named file to save the SSIM of
	   each individual frame. When filename equals "-" the data is sent to
	   standard output.

       The file printed if stats_file is selected, contains a sequence of
       key/value pairs of the form key:value for each compared couple of
       frames.

       A description of each shown parameter follows:

       n   sequential number of the input frame, starting from 1

       Y, U, V, R, G, B
	   SSIM of the compared frames for the component specified by the
	   suffix.

       All SSIM of the compared frames for the whole frame.

       dB  Same as above but in dB representation.

       This filter also supports the framesync options.

       For example:

	       movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
	       [main][ref] ssim="stats_file=stats.log" [out]

       On this example the input file being processed is compared with the
       reference file ref_movie.mpg. The SSIM of each individual frame is
       stored in stats.log.

       Another example with both psnr and ssim at same time:

	       ffmpeg -i main.mpg -i ref.mpg -lavfi  "ssim;[0:v][1:v]psnr" -f null -

   stereo3d
       Convert between different stereoscopic image formats.

       The filters accept the following options:

       in  Set stereoscopic image format of input.

	   Available values for input image formats are:

	   sbsl
	       side by side parallel (left eye left, right eye right)

	   sbsr
	       side by side crosseye (right eye left, left eye right)

	   sbs2l
	       side by side parallel with half width resolution (left eye
	       left, right eye right)

	   sbs2r
	       side by side crosseye with half width resolution (right eye
	       left, left eye right)

	   abl above-below (left eye above, right eye below)

	   abr above-below (right eye above, left eye below)

	   ab2l
	       above-below with half height resolution (left eye above, right
	       eye below)

	   ab2r
	       above-below with half height resolution (right eye above, left
	       eye below)

	   al  alternating frames (left eye first, right eye second)

	   ar  alternating frames (right eye first, left eye second)

	   irl interleaved rows (left eye has top row, right eye starts on
	       next row)

	   irr interleaved rows (right eye has top row, left eye starts on
	       next row)

	   icl interleaved columns, left eye first

	   icr interleaved columns, right eye first

	       Default value is sbsl.

       out Set stereoscopic image format of output.

	   sbsl
	       side by side parallel (left eye left, right eye right)

	   sbsr
	       side by side crosseye (right eye left, left eye right)

	   sbs2l
	       side by side parallel with half width resolution (left eye
	       left, right eye right)

	   sbs2r
	       side by side crosseye with half width resolution (right eye
	       left, left eye right)

	   abl above-below (left eye above, right eye below)

	   abr above-below (right eye above, left eye below)

	   ab2l
	       above-below with half height resolution (left eye above, right
	       eye below)

	   ab2r
	       above-below with half height resolution (right eye above, left
	       eye below)

	   al  alternating frames (left eye first, right eye second)

	   ar  alternating frames (right eye first, left eye second)

	   irl interleaved rows (left eye has top row, right eye starts on
	       next row)

	   irr interleaved rows (right eye has top row, left eye starts on
	       next row)

	   arbg
	       anaglyph red/blue gray (red filter on left eye, blue filter on
	       right eye)

	   argg
	       anaglyph red/green gray (red filter on left eye, green filter
	       on right eye)

	   arcg
	       anaglyph red/cyan gray (red filter on left eye, cyan filter on
	       right eye)

	   arch
	       anaglyph red/cyan half colored (red filter on left eye, cyan
	       filter on right eye)

	   arcc
	       anaglyph red/cyan color (red filter on left eye, cyan filter on
	       right eye)

	   arcd
	       anaglyph red/cyan color optimized with the least squares
	       projection of dubois (red filter on left eye, cyan filter on
	       right eye)

	   agmg
	       anaglyph green/magenta gray (green filter on left eye, magenta
	       filter on right eye)

	   agmh
	       anaglyph green/magenta half colored (green filter on left eye,
	       magenta filter on right eye)

	   agmc
	       anaglyph green/magenta colored (green filter on left eye,
	       magenta filter on right eye)

	   agmd
	       anaglyph green/magenta color optimized with the least squares
	       projection of dubois (green filter on left eye, magenta filter
	       on right eye)

	   aybg
	       anaglyph yellow/blue gray (yellow filter on left eye, blue
	       filter on right eye)

	   aybh
	       anaglyph yellow/blue half colored (yellow filter on left eye,
	       blue filter on right eye)

	   aybc
	       anaglyph yellow/blue colored (yellow filter on left eye, blue
	       filter on right eye)

	   aybd
	       anaglyph yellow/blue color optimized with the least squares
	       projection of dubois (yellow filter on left eye, blue filter on
	       right eye)

	   ml  mono output (left eye only)

	   mr  mono output (right eye only)

	   chl checkerboard, left eye first

	   chr checkerboard, right eye first

	   icl interleaved columns, left eye first

	   icr interleaved columns, right eye first

	   hdmi
	       HDMI frame pack

	   Default value is arcd.

       Examples

       ·   Convert input video from side by side parallel to anaglyph
	   yellow/blue dubois:

		   stereo3d=sbsl:aybd

       ·   Convert input video from above below (left eye above, right eye
	   below) to side by side crosseye.

		   stereo3d=abl:sbsr

   streamselect, astreamselect
       Select video or audio streams.

       The filter accepts the following options:

       inputs
	   Set number of inputs. Default is 2.

       map Set input indexes to remap to outputs.

       Commands

       The "streamselect" and "astreamselect" filter supports the following
       commands:

       map Set input indexes to remap to outputs.

       Examples

       ·   Select first 5 seconds 1st stream and rest of time 2nd stream:

		   sendcmd='5.0 streamselect map 1',streamselect=inputs=2:map=0

       ·   Same as above, but for audio:

		   asendcmd='5.0 astreamselect map 1',astreamselect=inputs=2:map=0

   sobel
       Apply sobel operator to input video stream.

       The filter accepts the following option:

       planes
	   Set which planes will be processed, unprocessed planes will be
	   copied.  By default value 0xf, all planes will be processed.

       scale
	   Set value which will be multiplied with filtered result.

       delta
	   Set value which will be added to filtered result.

   spp
       Apply a simple postprocessing filter that compresses and decompresses
       the image at several (or - in the case of quality level 6 - all) shifts
       and average the results.

       The filter accepts the following options:

       quality
	   Set quality. This option defines the number of levels for
	   averaging. It accepts an integer in the range 0-6. If set to 0, the
	   filter will have no effect. A value of 6 means the higher quality.
	   For each increment of that value the speed drops by a factor of
	   approximately 2.  Default value is 3.

       qp  Force a constant quantization parameter. If not set, the filter
	   will use the QP from the video stream (if available).

       mode
	   Set thresholding mode. Available modes are:

	   hard
	       Set hard thresholding (default).

	   soft
	       Set soft thresholding (better de-ringing effect, but likely
	       blurrier).

       use_bframe_qp
	   Enable the use of the QP from the B-Frames if set to 1. Using this
	   option may cause flicker since the B-Frames have often larger QP.
	   Default is 0 (not enabled).

   sr
       Scale the input by applying one of the super-resolution methods based
       on convolutional neural networks.

       Training scripts as well as scripts for model generation are provided
       in the repository at <https://github.com/HighVoltageRocknRoll/sr.git>.

       The filter accepts the following options:

       model
	   Specify which super-resolution model to use. This option accepts
	   the following values:

	   srcnn
	       Super-Resolution Convolutional Neural Network model.  See
	       <https://arxiv.org/abs/1501.00092>.

	   espcn
	       Efficient Sub-Pixel Convolutional Neural Network model.	See
	       <https://arxiv.org/abs/1609.05158>.

	   Default value is srcnn.

       dnn_backend
	   Specify which DNN backend to use for model loading and execution.
	   This option accepts the following values:

	   native
	       Native implementation of DNN loading and execution.

	   tensorflow
	       TensorFlow backend. To enable this backend you need to install
	       the TensorFlow for C library (see
	       <https://www.tensorflow.org/install/install_c>) and configure
	       FFmpeg with "--enable-libtensorflow"

	   Default value is native.

       scale_factor
	   Set scale factor for SRCNN model, for which custom model file was
	   provided.  Allowed values are 2, 3 and 4. Default value is 2.
	   Scale factor is necessary for SRCNN model, because it accepts input
	   upscaled using bicubic upscaling with proper scale factor.

       model_filename
	   Set path to model file specifying network architecture and its
	   parameters.	Note that different backends use different file
	   formats. TensorFlow backend can load files for both formats, while
	   native backend can load files for only its format.

   subtitles
       Draw subtitles on top of input video using the libass library.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-libass". This filter also requires a build with libavcodec
       and libavformat to convert the passed subtitles file to ASS (Advanced
       Substation Alpha) subtitles format.

       The filter accepts the following options:

       filename, f
	   Set the filename of the subtitle file to read. It must be
	   specified.

       original_size
	   Specify the size of the original video, the video for which the ASS
	   file was composed. For the syntax of this option, check the "Video
	   size" section in the ffmpeg-utils manual.  Due to a misdesign in
	   ASS aspect ratio arithmetic, this is necessary to correctly scale
	   the fonts if the aspect ratio has been changed.

       fontsdir
	   Set a directory path containing fonts that can be used by the
	   filter.  These fonts will be used in addition to whatever the font
	   provider uses.

       alpha
	   Process alpha channel, by default alpha channel is untouched.

       charenc
	   Set subtitles input character encoding. "subtitles" filter only.
	   Only useful if not UTF-8.

       stream_index, si
	   Set subtitles stream index. "subtitles" filter only.

       force_style
	   Override default style or script info parameters of the subtitles.
	   It accepts a string containing ASS style format "KEY=VALUE" couples
	   separated by ",".

       If the first key is not specified, it is assumed that the first value
       specifies the filename.

       For example, to render the file sub.srt on top of the input video, use
       the command:

	       subtitles=sub.srt

       which is equivalent to:

	       subtitles=filename=sub.srt

       To render the default subtitles stream from file video.mkv, use:

	       subtitles=video.mkv

       To render the second subtitles stream from that file, use:

	       subtitles=video.mkv:si=1

       To make the subtitles stream from sub.srt appear in 80% transparent
       blue "DejaVu Serif", use:

	       subtitles=sub.srt:force_style='FontName=DejaVu Serif,PrimaryColour=&HCCFF0000'

   super2xsai
       Scale the input by 2x and smooth using the Super2xSaI (Scale and
       Interpolate) pixel art scaling algorithm.

       Useful for enlarging pixel art images without reducing sharpness.

   swaprect
       Swap two rectangular objects in video.

       This filter accepts the following options:

       w   Set object width.

       h   Set object height.

       x1  Set 1st rect x coordinate.

       y1  Set 1st rect y coordinate.

       x2  Set 2nd rect x coordinate.

       y2  Set 2nd rect y coordinate.

	   All expressions are evaluated once for each frame.

       The all options are expressions containing the following constants:

       w
       h   The input width and height.

       a   same as w / h

       sar input sample aspect ratio

       dar input display aspect ratio, it is the same as (w / h) * sar

       n   The number of the input frame, starting from 0.

       t   The timestamp expressed in seconds. It's NAN if the input timestamp
	   is unknown.

       pos the position in the file of the input frame, NAN if unknown

   swapuv
       Swap U & V plane.

   telecine
       Apply telecine process to the video.

       This filter accepts the following options:

       first_field
	   top, t
	       top field first

	   bottom, b
	       bottom field first The default value is "top".

       pattern
	   A string of numbers representing the pulldown pattern you wish to
	   apply.  The default value is 23.

	       Some typical patterns:

	       NTSC output (30i):
	       27.5p: 32222
	       24p: 23 (classic)
	       24p: 2332 (preferred)
	       20p: 33
	       18p: 334
	       16p: 3444

	       PAL output (25i):
	       27.5p: 12222
	       24p: 222222222223 ("Euro pulldown")
	       16.67p: 33
	       16p: 33333334

   threshold
       Apply threshold effect to video stream.

       This filter needs four video streams to perform thresholding.  First
       stream is stream we are filtering.  Second stream is holding threshold
       values, third stream is holding min values, and last, fourth stream is
       holding max values.

       The filter accepts the following option:

       planes
	   Set which planes will be processed, unprocessed planes will be
	   copied.  By default value 0xf, all planes will be processed.

       For example if first stream pixel's component value is less then
       threshold value of pixel component from 2nd threshold stream, third
       stream value will picked, otherwise fourth stream pixel component value
       will be picked.

       Using color source filter one can perform various types of
       thresholding:

       Examples

       ·   Binary threshold, using gray color as threshold:

		   ffmpeg -i 320x240.avi -f lavfi -i color=gray -f lavfi -i color=black -f lavfi -i color=white -lavfi threshold output.avi

       ·   Inverted binary threshold, using gray color as threshold:

		   ffmpeg -i 320x240.avi -f lavfi -i color=gray -f lavfi -i color=white -f lavfi -i color=black -lavfi threshold output.avi

       ·   Truncate binary threshold, using gray color as threshold:

		   ffmpeg -i 320x240.avi -f lavfi -i color=gray -i 320x240.avi -f lavfi -i color=gray -lavfi threshold output.avi

       ·   Threshold to zero, using gray color as threshold:

		   ffmpeg -i 320x240.avi -f lavfi -i color=gray -f lavfi -i color=white -i 320x240.avi -lavfi threshold output.avi

       ·   Inverted threshold to zero, using gray color as threshold:

		   ffmpeg -i 320x240.avi -f lavfi -i color=gray -i 320x240.avi -f lavfi -i color=white -lavfi threshold output.avi

   thumbnail
       Select the most representative frame in a given sequence of consecutive
       frames.

       The filter accepts the following options:

       n   Set the frames batch size to analyze; in a set of n frames, the
	   filter will pick one of them, and then handle the next batch of n
	   frames until the end. Default is 100.

       Since the filter keeps track of the whole frames sequence, a bigger n
       value will result in a higher memory usage, so a high value is not
       recommended.

       Examples

       ·   Extract one picture each 50 frames:

		   thumbnail=50

       ·   Complete example of a thumbnail creation with ffmpeg:

		   ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png

   tile
       Tile several successive frames together.

       The filter accepts the following options:

       layout
	   Set the grid size (i.e. the number of lines and columns). For the
	   syntax of this option, check the "Video size" section in the
	   ffmpeg-utils manual.

       nb_frames
	   Set the maximum number of frames to render in the given area. It
	   must be less than or equal to wxh. The default value is 0, meaning
	   all the area will be used.

       margin
	   Set the outer border margin in pixels.

       padding
	   Set the inner border thickness (i.e. the number of pixels between
	   frames). For more advanced padding options (such as having
	   different values for the edges), refer to the pad video filter.

       color
	   Specify the color of the unused area. For the syntax of this
	   option, check the "Color" section in the ffmpeg-utils manual.  The
	   default value of color is "black".

       overlap
	   Set the number of frames to overlap when tiling several successive
	   frames together.  The value must be between 0 and nb_frames - 1.

       init_padding
	   Set the number of frames to initially be empty before displaying
	   first output frame.	This controls how soon will one get first
	   output frame.  The value must be between 0 and nb_frames - 1.

       Examples

       ·   Produce 8x8 PNG tiles of all keyframes (-skip_frame nokey) in a
	   movie:

		   ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png

	   The -vsync 0 is necessary to prevent ffmpeg from duplicating each
	   output frame to accommodate the originally detected frame rate.

       ·   Display 5 pictures in an area of "3x2" frames, with 7 pixels
	   between them, and 2 pixels of initial margin, using mixed flat and
	   named options:

		   tile=3x2:nb_frames=5:padding=7:margin=2

   tinterlace
       Perform various types of temporal field interlacing.

       Frames are counted starting from 1, so the first input frame is
       considered odd.

       The filter accepts the following options:

       mode
	   Specify the mode of the interlacing. This option can also be
	   specified as a value alone. See below for a list of values for this
	   option.

	   Available values are:

	   merge, 0
	       Move odd frames into the upper field, even into the lower
	       field, generating a double height frame at half frame rate.

			------> time
		       Input:
		       Frame 1	       Frame 2	       Frame 3	       Frame 4

		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444

		       Output:
		       11111			       33333
		       22222			       44444
		       11111			       33333
		       22222			       44444
		       11111			       33333
		       22222			       44444
		       11111			       33333
		       22222			       44444

	   drop_even, 1
	       Only output odd frames, even frames are dropped, generating a
	       frame with unchanged height at half frame rate.

			------> time
		       Input:
		       Frame 1	       Frame 2	       Frame 3	       Frame 4

		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444

		       Output:
		       11111			       33333
		       11111			       33333
		       11111			       33333
		       11111			       33333

	   drop_odd, 2
	       Only output even frames, odd frames are dropped, generating a
	       frame with unchanged height at half frame rate.

			------> time
		       Input:
		       Frame 1	       Frame 2	       Frame 3	       Frame 4

		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444

		       Output:
				       22222			       44444
				       22222			       44444
				       22222			       44444
				       22222			       44444

	   pad, 3
	       Expand each frame to full height, but pad alternate lines with
	       black, generating a frame with double height at the same input
	       frame rate.

			------> time
		       Input:
		       Frame 1	       Frame 2	       Frame 3	       Frame 4

		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444

		       Output:
		       11111	       .....	       33333	       .....
		       .....	       22222	       .....	       44444
		       11111	       .....	       33333	       .....
		       .....	       22222	       .....	       44444
		       11111	       .....	       33333	       .....
		       .....	       22222	       .....	       44444
		       11111	       .....	       33333	       .....
		       .....	       22222	       .....	       44444

	   interleave_top, 4
	       Interleave the upper field from odd frames with the lower field
	       from even frames, generating a frame with unchanged height at
	       half frame rate.

			------> time
		       Input:
		       Frame 1	       Frame 2	       Frame 3	       Frame 4

		       11111<-	       22222	       33333<-	       44444
		       11111	       22222<-	       33333	       44444<-
		       11111<-	       22222	       33333<-	       44444
		       11111	       22222<-	       33333	       44444<-

		       Output:
		       11111			       33333
		       22222			       44444
		       11111			       33333
		       22222			       44444

	   interleave_bottom, 5
	       Interleave the lower field from odd frames with the upper field
	       from even frames, generating a frame with unchanged height at
	       half frame rate.

			------> time
		       Input:
		       Frame 1	       Frame 2	       Frame 3	       Frame 4

		       11111	       22222<-	       33333	       44444<-
		       11111<-	       22222	       33333<-	       44444
		       11111	       22222<-	       33333	       44444<-
		       11111<-	       22222	       33333<-	       44444

		       Output:
		       22222			       44444
		       11111			       33333
		       22222			       44444
		       11111			       33333

	   interlacex2, 6
	       Double frame rate with unchanged height. Frames are inserted
	       each containing the second temporal field from the previous
	       input frame and the first temporal field from the next input
	       frame. This mode relies on the top_field_first flag. Useful for
	       interlaced video displays with no field synchronisation.

			------> time
		       Input:
		       Frame 1	       Frame 2	       Frame 3	       Frame 4

		       11111	       22222	       33333	       44444
			11111		22222		33333		44444
		       11111	       22222	       33333	       44444
			11111		22222		33333		44444

		       Output:
		       11111   22222   22222   33333   33333   44444   44444
			11111	11111	22222	22222	33333	33333	44444
		       11111   22222   22222   33333   33333   44444   44444
			11111	11111	22222	22222	33333	33333	44444

	   mergex2, 7
	       Move odd frames into the upper field, even into the lower
	       field, generating a double height frame at same frame rate.

			------> time
		       Input:
		       Frame 1	       Frame 2	       Frame 3	       Frame 4

		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444
		       11111	       22222	       33333	       44444

		       Output:
		       11111	       33333	       33333	       55555
		       22222	       22222	       44444	       44444
		       11111	       33333	       33333	       55555
		       22222	       22222	       44444	       44444
		       11111	       33333	       33333	       55555
		       22222	       22222	       44444	       44444
		       11111	       33333	       33333	       55555
		       22222	       22222	       44444	       44444

	   Numeric values are deprecated but are accepted for backward
	   compatibility reasons.

	   Default mode is "merge".

       flags
	   Specify flags influencing the filter process.

	   Available value for flags is:

	   low_pass_filter, vlfp
	       Enable linear vertical low-pass filtering in the filter.
	       Vertical low-pass filtering is required when creating an
	       interlaced destination from a progressive source which contains
	       high-frequency vertical detail. Filtering will reduce interlace
	       'twitter' and Moire patterning.

	   complex_filter, cvlfp
	       Enable complex vertical low-pass filtering.  This will slightly
	       less reduce interlace 'twitter' and Moire patterning but better
	       retain detail and subjective sharpness impression.

	   Vertical low-pass filtering can only be enabled for mode
	   interleave_top and interleave_bottom.

   tmix
       Mix successive video frames.

       A description of the accepted options follows.

       frames
	   The number of successive frames to mix. If unspecified, it defaults
	   to 3.

       weights
	   Specify weight of each input video frame.  Each weight is separated
	   by space. If number of weights is smaller than number of frames
	   last specified weight will be used for all remaining unset weights.

       scale
	   Specify scale, if it is set it will be multiplied with sum of each
	   weight multiplied with pixel values to give final destination pixel
	   value. By default scale is auto scaled to sum of weights.

       Examples

       ·   Average 7 successive frames:

		   tmix=frames=7:weights="1 1 1 1 1 1 1"

       ·   Apply simple temporal convolution:

		   tmix=frames=3:weights="-1 3 -1"

       ·   Similar as above but only showing temporal differences:

		   tmix=frames=3:weights="-1 2 -1":scale=1

   tonemap
       Tone map colors from different dynamic ranges.

       This filter expects data in single precision floating point, as it
       needs to operate on (and can output) out-of-range values. Another
       filter, such as zscale, is needed to convert the resulting frame to a
       usable format.

       The tonemapping algorithms implemented only work on linear light, so
       input data should be linearized beforehand (and possibly correctly
       tagged).

	       ffmpeg -i INPUT -vf zscale=transfer=linear,tonemap=clip,zscale=transfer=bt709,format=yuv420p OUTPUT

       Options

       The filter accepts the following options.

       tonemap
	   Set the tone map algorithm to use.

	   Possible values are:

	   none
	       Do not apply any tone map, only desaturate overbright pixels.

	   clip
	       Hard-clip any out-of-range values. Use it for perfect color
	       accuracy for in-range values, while distorting out-of-range
	       values.

	   linear
	       Stretch the entire reference gamut to a linear multiple of the
	       display.

	   gamma
	       Fit a logarithmic transfer between the tone curves.

	   reinhard
	       Preserve overall image brightness with a simple curve, using
	       nonlinear contrast, which results in flattening details and
	       degrading color accuracy.

	   hable
	       Preserve both dark and bright details better than reinhard, at
	       the cost of slightly darkening everything. Use it when detail
	       preservation is more important than color and brightness
	       accuracy.

	   mobius
	       Smoothly map out-of-range values, while retaining contrast and
	       colors for in-range material as much as possible. Use it when
	       color accuracy is more important than detail preservation.

	   Default is none.

       param
	   Tune the tone mapping algorithm.

	   This affects the following algorithms:

	   none
	       Ignored.

	   linear
	       Specifies the scale factor to use while stretching.  Default to
	       1.0.

	   gamma
	       Specifies the exponent of the function.	Default to 1.8.

	   clip
	       Specify an extra linear coefficient to multiply into the signal
	       before clipping.  Default to 1.0.

	   reinhard
	       Specify the local contrast coefficient at the display peak.
	       Default to 0.5, which means that in-gamut values will be about
	       half as bright as when clipping.

	   hable
	       Ignored.

	   mobius
	       Specify the transition point from linear to mobius transform.
	       Every value below this point is guaranteed to be mapped 1:1.
	       The higher the value, the more accurate the result will be, at
	       the cost of losing bright details.  Default to 0.3, which due
	       to the steep initial slope still preserves in-range colors
	       fairly accurately.

       desat
	   Apply desaturation for highlights that exceed this level of
	   brightness. The higher the parameter, the more color information
	   will be preserved. This setting helps prevent unnaturally blown-out
	   colors for super-highlights, by (smoothly) turning into white
	   instead. This makes images feel more natural, at the cost of
	   reducing information about out-of-range colors.

	   The default of 2.0 is somewhat conservative and will mostly just
	   apply to skies or directly sunlit surfaces. A setting of 0.0
	   disables this option.

	   This option works only if the input frame has a supported color
	   tag.

       peak
	   Override signal/nominal/reference peak with this value. Useful when
	   the embedded peak information in display metadata is not reliable
	   or when tone mapping from a lower range to a higher range.

   transpose
       Transpose rows with columns in the input video and optionally flip it.

       It accepts the following parameters:

       dir Specify the transposition direction.

	   Can assume the following values:

	   0, 4, cclock_flip
	       Rotate by 90 degrees counterclockwise and vertically flip
	       (default), that is:

		       L.R     L.l
		       . . ->  . .
		       l.r     R.r

	   1, 5, clock
	       Rotate by 90 degrees clockwise, that is:

		       L.R     l.L
		       . . ->  . .
		       l.r     r.R

	   2, 6, cclock
	       Rotate by 90 degrees counterclockwise, that is:

		       L.R     R.r
		       . . ->  . .
		       l.r     L.l

	   3, 7, clock_flip
	       Rotate by 90 degrees clockwise and vertically flip, that is:

		       L.R     r.R
		       . . ->  . .
		       l.r     l.L

	   For values between 4-7, the transposition is only done if the input
	   video geometry is portrait and not landscape. These values are
	   deprecated, the "passthrough" option should be used instead.

	   Numerical values are deprecated, and should be dropped in favor of
	   symbolic constants.

       passthrough
	   Do not apply the transposition if the input geometry matches the
	   one specified by the specified value. It accepts the following
	   values:

	   none
	       Always apply transposition.

	   portrait
	       Preserve portrait geometry (when height >= width).

	   landscape
	       Preserve landscape geometry (when width >= height).

	   Default value is "none".

       For example to rotate by 90 degrees clockwise and preserve portrait
       layout:

	       transpose=dir=1:passthrough=portrait

       The command above can also be specified as:

	       transpose=1:portrait

   trim
       Trim the input so that the output contains one continuous subpart of
       the input.

       It accepts the following parameters:

       start
	   Specify the time of the start of the kept section, i.e. the frame
	   with the timestamp start will be the first frame in the output.

       end Specify the time of the first frame that will be dropped, i.e. the
	   frame immediately preceding the one with the timestamp end will be
	   the last frame in the output.

       start_pts
	   This is the same as start, except this option sets the start
	   timestamp in timebase units instead of seconds.

       end_pts
	   This is the same as end, except this option sets the end timestamp
	   in timebase units instead of seconds.

       duration
	   The maximum duration of the output in seconds.

       start_frame
	   The number of the first frame that should be passed to the output.

       end_frame
	   The number of the first frame that should be dropped.

       start, end, and duration are expressed as time duration specifications;
       see the Time duration section in the ffmpeg-utils(1) manual for the
       accepted syntax.

       Note that the first two sets of the start/end options and the duration
       option look at the frame timestamp, while the _frame variants simply
       count the frames that pass through the filter. Also note that this
       filter does not modify the timestamps. If you wish for the output
       timestamps to start at zero, insert a setpts filter after the trim
       filter.

       If multiple start or end options are set, this filter tries to be
       greedy and keep all the frames that match at least one of the specified
       constraints. To keep only the part that matches all the constraints at
       once, chain multiple trim filters.

       The defaults are such that all the input is kept. So it is possible to
       set e.g.  just the end values to keep everything before the specified
       time.

       Examples:

       ·   Drop everything except the second minute of input:

		   ffmpeg -i INPUT -vf trim=60:120

       ·   Keep only the first second:

		   ffmpeg -i INPUT -vf trim=duration=1

   unpremultiply
       Apply alpha unpremultiply effect to input video stream using first
       plane of second stream as alpha.

       Both streams must have same dimensions and same pixel format.

       The filter accepts the following option:

       planes
	   Set which planes will be processed, unprocessed planes will be
	   copied.  By default value 0xf, all planes will be processed.

	   If the format has 1 or 2 components, then luma is bit 0.  If the
	   format has 3 or 4 components: for RGB formats bit 0 is green, bit 1
	   is blue and bit 2 is red; for YUV formats bit 0 is luma, bit 1 is
	   chroma-U and bit 2 is chroma-V.  If present, the alpha channel is
	   always the last bit.

       inplace
	   Do not require 2nd input for processing, instead use alpha plane
	   from input stream.

   unsharp
       Sharpen or blur the input video.

       It accepts the following parameters:

       luma_msize_x, lx
	   Set the luma matrix horizontal size. It must be an odd integer
	   between 3 and 23. The default value is 5.

       luma_msize_y, ly
	   Set the luma matrix vertical size. It must be an odd integer
	   between 3 and 23. The default value is 5.

       luma_amount, la
	   Set the luma effect strength. It must be a floating point number,
	   reasonable values lay between -1.5 and 1.5.

	   Negative values will blur the input video, while positive values
	   will sharpen it, a value of zero will disable the effect.

	   Default value is 1.0.

       chroma_msize_x, cx
	   Set the chroma matrix horizontal size. It must be an odd integer
	   between 3 and 23. The default value is 5.

       chroma_msize_y, cy
	   Set the chroma matrix vertical size. It must be an odd integer
	   between 3 and 23. The default value is 5.

       chroma_amount, ca
	   Set the chroma effect strength. It must be a floating point number,
	   reasonable values lay between -1.5 and 1.5.

	   Negative values will blur the input video, while positive values
	   will sharpen it, a value of zero will disable the effect.

	   Default value is 0.0.

       All parameters are optional and default to the equivalent of the string
       '5:5:1.0:5:5:0.0'.

       Examples

       ·   Apply strong luma sharpen effect:

		   unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5

       ·   Apply a strong blur of both luma and chroma parameters:

		   unsharp=7:7:-2:7:7:-2

   uspp
       Apply ultra slow/simple postprocessing filter that compresses and
       decompresses the image at several (or - in the case of quality level 8
       - all) shifts and average the results.

       The way this differs from the behavior of spp is that uspp actually
       encodes & decodes each case with libavcodec Snow, whereas spp uses a
       simplified intra only 8x8 DCT similar to MJPEG.

       The filter accepts the following options:

       quality
	   Set quality. This option defines the number of levels for
	   averaging. It accepts an integer in the range 0-8. If set to 0, the
	   filter will have no effect. A value of 8 means the higher quality.
	   For each increment of that value the speed drops by a factor of
	   approximately 2.  Default value is 3.

       qp  Force a constant quantization parameter. If not set, the filter
	   will use the QP from the video stream (if available).

   vaguedenoiser
       Apply a wavelet based denoiser.

       It transforms each frame from the video input into the wavelet domain,
       using Cohen-Daubechies-Feauveau 9/7. Then it applies some filtering to
       the obtained coefficients. It does an inverse wavelet transform after.
       Due to wavelet properties, it should give a nice smoothed result, and
       reduced noise, without blurring picture features.

       This filter accepts the following options:

       threshold
	   The filtering strength. The higher, the more filtered the video
	   will be.  Hard thresholding can use a higher threshold than soft
	   thresholding before the video looks overfiltered. Default value is
	   2.

       method
	   The filtering method the filter will use.

	   It accepts the following values:

	   hard
	       All values under the threshold will be zeroed.

	   soft
	       All values under the threshold will be zeroed. All values above
	       will be reduced by the threshold.

	   garrote
	       Scales or nullifies coefficients - intermediary between (more)
	       soft and (less) hard thresholding.

	   Default is garrote.

       nsteps
	   Number of times, the wavelet will decompose the picture. Picture
	   can't be decomposed beyond a particular point (typically, 8 for a
	   640x480 frame - as 2^9 = 512 > 480). Valid values are integers
	   between 1 and 32. Default value is 6.

       percent
	   Partial of full denoising (limited coefficients shrinking), from 0
	   to 100. Default value is 85.

       planes
	   A list of the planes to process. By default all planes are
	   processed.

   vectorscope
       Display 2 color component values in the two dimensional graph (which is
       called a vectorscope).

       This filter accepts the following options:

       mode, m
	   Set vectorscope mode.

	   It accepts the following values:

	   gray
	       Gray values are displayed on graph, higher brightness means
	       more pixels have same component color value on location in
	       graph. This is the default mode.

	   color
	       Gray values are displayed on graph. Surrounding pixels values
	       which are not present in video frame are drawn in gradient of 2
	       color components which are set by option "x" and "y". The 3rd
	       color component is static.

	   color2
	       Actual color components values present in video frame are
	       displayed on graph.

	   color3
	       Similar as color2 but higher frequency of same values "x" and
	       "y" on graph increases value of another color component, which
	       is luminance by default values of "x" and "y".

	   color4
	       Actual colors present in video frame are displayed on graph. If
	       two different colors map to same position on graph then color
	       with higher value of component not present in graph is picked.

	   color5
	       Gray values are displayed on graph. Similar to "color" but with
	       3rd color component picked from radial gradient.

       x   Set which color component will be represented on X-axis. Default is
	   1.

       y   Set which color component will be represented on Y-axis. Default is
	   2.

       intensity, i
	   Set intensity, used by modes: gray, color, color3 and color5 for
	   increasing brightness of color component which represents frequency
	   of (X, Y) location in graph.

       envelope, e
	   none
	       No envelope, this is default.

	   instant
	       Instant envelope, even darkest single pixel will be clearly
	       highlighted.

	   peak
	       Hold maximum and minimum values presented in graph over time.
	       This way you can still spot out of range values without
	       constantly looking at vectorscope.

	   peak+instant
	       Peak and instant envelope combined together.

       graticule, g
	   Set what kind of graticule to draw.

	   none
	   green
	   color
       opacity, o
	   Set graticule opacity.

       flags, f
	   Set graticule flags.

	   white
	       Draw graticule for white point.

	   black
	       Draw graticule for black point.

	   name
	       Draw color points short names.

       bgopacity, b
	   Set background opacity.

       lthreshold, l
	   Set low threshold for color component not represented on X or Y
	   axis.  Values lower than this value will be ignored. Default is 0.
	   Note this value is multiplied with actual max possible value one
	   pixel component can have. So for 8-bit input and low threshold
	   value of 0.1 actual threshold is 0.1 * 255 = 25.

       hthreshold, h
	   Set high threshold for color component not represented on X or Y
	   axis.  Values higher than this value will be ignored. Default is 1.
	   Note this value is multiplied with actual max possible value one
	   pixel component can have. So for 8-bit input and high threshold
	   value of 0.9 actual threshold is 0.9 * 255 = 230.

       colorspace, c
	   Set what kind of colorspace to use when drawing graticule.

	   auto
	   601
	   709

	   Default is auto.

   vidstabdetect
       Analyze video stabilization/deshaking. Perform pass 1 of 2, see
       vidstabtransform for pass 2.

       This filter generates a file with relative translation and rotation
       transform information about subsequent frames, which is then used by
       the vidstabtransform filter.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-libvidstab".

       This filter accepts the following options:

       result
	   Set the path to the file used to write the transforms information.
	   Default value is transforms.trf.

       shakiness
	   Set how shaky the video is and how quick the camera is. It accepts
	   an integer in the range 1-10, a value of 1 means little shakiness,
	   a value of 10 means strong shakiness. Default value is 5.

       accuracy
	   Set the accuracy of the detection process. It must be a value in
	   the range 1-15. A value of 1 means low accuracy, a value of 15
	   means high accuracy. Default value is 15.

       stepsize
	   Set stepsize of the search process. The region around minimum is
	   scanned with 1 pixel resolution. Default value is 6.

       mincontrast
	   Set minimum contrast. Below this value a local measurement field is
	   discarded. Must be a floating point value in the range 0-1. Default
	   value is 0.3.

       tripod
	   Set reference frame number for tripod mode.

	   If enabled, the motion of the frames is compared to a reference
	   frame in the filtered stream, identified by the specified number.
	   The idea is to compensate all movements in a more-or-less static
	   scene and keep the camera view absolutely still.

	   If set to 0, it is disabled. The frames are counted starting from
	   1.

       show
	   Show fields and transforms in the resulting frames. It accepts an
	   integer in the range 0-2. Default value is 0, which disables any
	   visualization.

       Examples

       ·   Use default values:

		   vidstabdetect

       ·   Analyze strongly shaky movie and put the results in file
	   mytransforms.trf:

		   vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"

       ·   Visualize the result of internal transformations in the resulting
	   video:

		   vidstabdetect=show=1

       ·   Analyze a video with medium shakiness using ffmpeg:

		   ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi

   vidstabtransform
       Video stabilization/deshaking: pass 2 of 2, see vidstabdetect for pass
       1.

       Read a file with transform information for each frame and
       apply/compensate them. Together with the vidstabdetect filter this can
       be used to deshake videos. See also
       <http://public.hronopik.de/vid.stab>. It is important to also use the
       unsharp filter, see below.

       To enable compilation of this filter you need to configure FFmpeg with
       "--enable-libvidstab".

       Options

       input
	   Set path to the file used to read the transforms. Default value is
	   transforms.trf.

       smoothing
	   Set the number of frames (value*2 + 1) used for lowpass filtering
	   the camera movements. Default value is 10.

	   For example a number of 10 means that 21 frames are used (10 in the
	   past and 10 in the future) to smoothen the motion in the video. A
	   larger value leads to a smoother video, but limits the acceleration
	   of the camera (pan/tilt movements). 0 is a special case where a
	   static camera is simulated.

       optalgo
	   Set the camera path optimization algorithm.

	   Accepted values are:

	   gauss
	       gaussian kernel low-pass filter on camera motion (default)

	   avg averaging on transformations

       maxshift
	   Set maximal number of pixels to translate frames. Default value is
	   -1, meaning no limit.

       maxangle
	   Set maximal angle in radians (degree*PI/180) to rotate frames.
	   Default value is -1, meaning no limit.

       crop
	   Specify how to deal with borders that may be visible due to
	   movement compensation.

	   Available values are:

	   keep
	       keep image information from previous frame (default)

	   black
	       fill the border black

       invert
	   Invert transforms if set to 1. Default value is 0.

       relative
	   Consider transforms as relative to previous frame if set to 1,
	   absolute if set to 0. Default value is 0.

       zoom
	   Set percentage to zoom. A positive value will result in a zoom-in
	   effect, a negative value in a zoom-out effect. Default value is 0
	   (no zoom).

       optzoom
	   Set optimal zooming to avoid borders.

	   Accepted values are:

	   0   disabled

	   1   optimal static zoom value is determined (only very strong
	       movements will lead to visible borders) (default)

	   2   optimal adaptive zoom value is determined (no borders will be
	       visible), see zoomspeed

	   Note that the value given at zoom is added to the one calculated
	   here.

       zoomspeed
	   Set percent to zoom maximally each frame (enabled when optzoom is
	   set to 2). Range is from 0 to 5, default value is 0.25.

       interpol
	   Specify type of interpolation.

	   Available values are:

	   no  no interpolation

	   linear
	       linear only horizontal

	   bilinear
	       linear in both directions (default)

	   bicubic
	       cubic in both directions (slow)

       tripod
	   Enable virtual tripod mode if set to 1, which is equivalent to
	   "relative=0:smoothing=0". Default value is 0.

	   Use also "tripod" option of vidstabdetect.

       debug
	   Increase log verbosity if set to 1. Also the detected global
	   motions are written to the temporary file global_motions.trf.
	   Default value is 0.

       Examples

       ·   Use ffmpeg for a typical stabilization with default values:

		   ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg

	   Note the use of the unsharp filter which is always recommended.

       ·   Zoom in a bit more and load transform data from a given file:

		   vidstabtransform=zoom=5:input="mytransforms.trf"

       ·   Smoothen the video even more:

		   vidstabtransform=smoothing=30

   vflip
       Flip the input video vertically.

       For example, to vertically flip a video with ffmpeg:

	       ffmpeg -i in.avi -vf "vflip" out.avi

   vfrdet
       Detect variable frame rate video.

       This filter tries to detect if the input is variable or constant frame
       rate.

       At end it will output number of frames detected as having variable
       delta pts, and ones with constant delta pts.  If there was frames with
       variable delta, than it will also show min and max delta encountered.

   vignette
       Make or reverse a natural vignetting effect.

       The filter accepts the following options:

       angle, a
	   Set lens angle expression as a number of radians.

	   The value is clipped in the "[0,PI/2]" range.

	   Default value: "PI/5"

       x0
       y0  Set center coordinates expressions. Respectively "w/2" and "h/2" by
	   default.

       mode
	   Set forward/backward mode.

	   Available modes are:

	   forward
	       The larger the distance from the central point, the darker the
	       image becomes.

	   backward
	       The larger the distance from the central point, the brighter
	       the image becomes.  This can be used to reverse a vignette
	       effect, though there is no automatic detection to extract the
	       lens angle and other settings (yet). It can also be used to
	       create a burning effect.

	   Default value is forward.

       eval
	   Set evaluation mode for the expressions (angle, x0, y0).

	   It accepts the following values:

	   init
	       Evaluate expressions only once during the filter
	       initialization.

	   frame
	       Evaluate expressions for each incoming frame. This is way
	       slower than the init mode since it requires all the scalers to
	       be re-computed, but it allows advanced dynamic expressions.

	   Default value is init.

       dither
	   Set dithering to reduce the circular banding effects. Default is 1
	   (enabled).

       aspect
	   Set vignette aspect. This setting allows one to adjust the shape of
	   the vignette.  Setting this value to the SAR of the input will make
	   a rectangular vignetting following the dimensions of the video.

	   Default is "1/1".

       Expressions

       The alpha, x0 and y0 expressions can contain the following parameters.

       w
       h   input width and height

       n   the number of input frame, starting from 0

       pts the PTS (Presentation TimeStamp) time of the filtered video frame,
	   expressed in TB units, NAN if undefined

       r   frame rate of the input video, NAN if the input frame rate is
	   unknown

       t   the PTS (Presentation TimeStamp) of the filtered video frame,
	   expressed in seconds, NAN if undefined

       tb  time base of the input video

       Examples

       ·   Apply simple strong vignetting effect:

		   vignette=PI/4

       ·   Make a flickering vignetting:

		   vignette='PI/4+random(1)*PI/50':eval=frame

   vmafmotion
       Obtain the average vmaf motion score of a video.  It is one of the
       component filters of VMAF.

       The obtained average motion score is printed through the logging
       system.

       In the below example the input file ref.mpg is being processed and
       score is computed.

	       ffmpeg -i ref.mpg -lavfi vmafmotion -f null -

   vstack
       Stack input videos vertically.

       All streams must be of same pixel format and of same width.

       Note that this filter is faster than using overlay and pad filter to
       create same output.

       The filter accept the following option:

       inputs
	   Set number of input streams. Default is 2.

       shortest
	   If set to 1, force the output to terminate when the shortest input
	   terminates. Default value is 0.

   w3fdif
       Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
       Deinterlacing Filter").

       Based on the process described by Martin Weston for BBC R&D, and
       implemented based on the de-interlace algorithm written by Jim
       Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter uses
       filter coefficients calculated by BBC R&D.

       There are two sets of filter coefficients, so called "simple": and
       "complex". Which set of filter coefficients is used can be set by
       passing an optional parameter:

       filter
	   Set the interlacing filter coefficients. Accepts one of the
	   following values:

	   simple
	       Simple filter coefficient set.

	   complex
	       More-complex filter coefficient set.

	   Default value is complex.

       deint
	   Specify which frames to deinterlace. Accept one of the following
	   values:

	   all Deinterlace all frames,

	   interlaced
	       Only deinterlace frames marked as interlaced.

	   Default value is all.

   waveform
       Video waveform monitor.

       The waveform monitor plots color component intensity. By default
       luminance only. Each column of the waveform corresponds to a column of
       pixels in the source video.

       It accepts the following options:

       mode, m
	   Can be either "row", or "column". Default is "column".  In row
	   mode, the graph on the left side represents color component value 0
	   and the right side represents value = 255. In column mode, the top
	   side represents color component value = 0 and bottom side
	   represents value = 255.

       intensity, i
	   Set intensity. Smaller values are useful to find out how many
	   values of the same luminance are distributed across input
	   rows/columns.  Default value is 0.04. Allowed range is [0, 1].

       mirror, r
	   Set mirroring mode. 0 means unmirrored, 1 means mirrored.  In
	   mirrored mode, higher values will be represented on the left side
	   for "row" mode and at the top for "column" mode. Default is 1
	   (mirrored).

       display, d
	   Set display mode.  It accepts the following values:

	   overlay
	       Presents information identical to that in the "parade", except
	       that the graphs representing color components are superimposed
	       directly over one another.

	       This display mode makes it easier to spot relative differences
	       or similarities in overlapping areas of the color components
	       that are supposed to be identical, such as neutral whites,
	       grays, or blacks.

	   stack
	       Display separate graph for the color components side by side in
	       "row" mode or one below the other in "column" mode.

	   parade
	       Display separate graph for the color components side by side in
	       "column" mode or one below the other in "row" mode.

	       Using this display mode makes it easy to spot color casts in
	       the highlights and shadows of an image, by comparing the
	       contours of the top and the bottom graphs of each waveform.
	       Since whites, grays, and blacks are characterized by exactly
	       equal amounts of red, green, and blue, neutral areas of the
	       picture should display three waveforms of roughly equal
	       width/height. If not, the correction is easy to perform by
	       making level adjustments the three waveforms.

	   Default is "stack".

       components, c
	   Set which color components to display. Default is 1, which means
	   only luminance or red color component if input is in RGB
	   colorspace. If is set for example to 7 it will display all 3 (if)
	   available color components.

       envelope, e
	   none
	       No envelope, this is default.

	   instant
	       Instant envelope, minimum and maximum values presented in graph
	       will be easily visible even with small "step" value.

	   peak
	       Hold minimum and maximum values presented in graph across time.
	       This way you can still spot out of range values without
	       constantly looking at waveforms.

	   peak+instant
	       Peak and instant envelope combined together.

       filter, f
	   lowpass
	       No filtering, this is default.

	   flat
	       Luma and chroma combined together.

	   aflat
	       Similar as above, but shows difference between blue and red
	       chroma.

	   xflat
	       Similar as above, but use different colors.

	   chroma
	       Displays only chroma.

	   color
	       Displays actual color value on waveform.

	   acolor
	       Similar as above, but with luma showing frequency of chroma
	       values.

       graticule, g
	   Set which graticule to display.

	   none
	       Do not display graticule.

	   green
	       Display green graticule showing legal broadcast ranges.

	   orange
	       Display orange graticule showing legal broadcast ranges.

       opacity, o
	   Set graticule opacity.

       flags, fl
	   Set graticule flags.

	   numbers
	       Draw numbers above lines. By default enabled.

	   dots
	       Draw dots instead of lines.

       scale, s
	   Set scale used for displaying graticule.

	   digital
	   millivolts
	   ire

	   Default is digital.

       bgopacity, b
	   Set background opacity.

   weave, doubleweave
       The "weave" takes a field-based video input and join each two
       sequential fields into single frame, producing a new double height clip
       with half the frame rate and half the frame count.

       The "doubleweave" works same as "weave" but without halving frame rate
       and frame count.

       It accepts the following option:

       first_field
	   Set first field. Available values are:

	   top, t
	       Set the frame as top-field-first.

	   bottom, b
	       Set the frame as bottom-field-first.

       Examples

       ·   Interlace video using select and separatefields filter:

		   separatefields,select=eq(mod(n,4),0)+eq(mod(n,4),3),weave

   xbr
       Apply the xBR high-quality magnification filter which is designed for
       pixel art. It follows a set of edge-detection rules, see
       <https://forums.libretro.com/t/xbr-algorithm-tutorial/123>.

       It accepts the following option:

       n   Set the scaling dimension: 2 for "2xBR", 3 for "3xBR" and 4 for
	   "4xBR".  Default is 3.

   yadif
       Deinterlace the input video ("yadif" means "yet another deinterlacing
       filter").

       It accepts the following parameters:

       mode
	   The interlacing mode to adopt. It accepts one of the following
	   values:

	   0, send_frame
	       Output one frame for each frame.

	   1, send_field
	       Output one frame for each field.

	   2, send_frame_nospatial
	       Like "send_frame", but it skips the spatial interlacing check.

	   3, send_field_nospatial
	       Like "send_field", but it skips the spatial interlacing check.

	   The default value is "send_frame".

       parity
	   The picture field parity assumed for the input interlaced video. It
	   accepts one of the following values:

	   0, tff
	       Assume the top field is first.

	   1, bff
	       Assume the bottom field is first.

	   -1, auto
	       Enable automatic detection of field parity.

	   The default value is "auto".  If the interlacing is unknown or the
	   decoder does not export this information, top field first will be
	   assumed.

       deint
	   Specify which frames to deinterlace. Accept one of the following
	   values:

	   0, all
	       Deinterlace all frames.

	   1, interlaced
	       Only deinterlace frames marked as interlaced.

	   The default value is "all".

   zoompan
       Apply Zoom & Pan effect.

       This filter accepts the following options:

       zoom, z
	   Set the zoom expression. Default is 1.

       x
       y   Set the x and y expression. Default is 0.

       d   Set the duration expression in number of frames.  This sets for how
	   many number of frames effect will last for single input image.

       s   Set the output image size, default is 'hd720'.

       fps Set the output frame rate, default is '25'.

       Each expression can contain the following constants:

       in_w, iw
	   Input width.

       in_h, ih
	   Input height.

       out_w, ow
	   Output width.

       out_h, oh
	   Output height.

       in  Input frame count.

       on  Output frame count.

       x
       y   Last calculated 'x' and 'y' position from 'x' and 'y' expression
	   for current input frame.

       px
       py  'x' and 'y' of last output frame of previous input frame or 0 when
	   there was not yet such frame (first input frame).

       zoom
	   Last calculated zoom from 'z' expression for current input frame.

       pzoom
	   Last calculated zoom of last output frame of previous input frame.

       duration
	   Number of output frames for current input frame. Calculated from
	   'd' expression for each input frame.

       pduration
	   number of output frames created for previous input frame

       a   Rational number: input width / input height

       sar sample aspect ratio

       dar display aspect ratio

       Examples

       ·   Zoom-in up to 1.5 and pan at same time to some spot near center of
	   picture:

		   zoompan=z='min(zoom+0.0015,1.5)':d=700:x='if(gte(zoom,1.5),x,x+1/a)':y='if(gte(zoom,1.5),y,y+1)':s=640x360

       ·   Zoom-in up to 1.5 and pan always at center of picture:

		   zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'

       ·   Same as above but without pausing:

		   zoompan=z='min(max(zoom,pzoom)+0.0015,1.5)':d=1:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'

   zscale
       Scale (resize) the input video, using the z.lib library:
       <https://github.com/sekrit-twc/zimg>. To enable compilation of this
       filter, you need to configure FFmpeg with "--enable-libzimg".

       The zscale filter forces the output display aspect ratio to be the same
       as the input, by changing the output sample aspect ratio.

       If the input image format is different from the format requested by the
       next filter, the zscale filter will convert the input to the requested
       format.

       Options

       The filter accepts the following options.

       width, w
       height, h
	   Set the output video dimension expression. Default value is the
	   input dimension.

	   If the width or w value is 0, the input width is used for the
	   output. If the height or h value is 0, the input height is used for
	   the output.

	   If one and only one of the values is -n with n >= 1, the zscale
	   filter will use a value that maintains the aspect ratio of the
	   input image, calculated from the other specified dimension. After
	   that it will, however, make sure that the calculated dimension is
	   divisible by n and adjust the value if necessary.

	   If both values are -n with n >= 1, the behavior will be identical
	   to both values being set to 0 as previously detailed.

	   See below for the list of accepted constants for use in the
	   dimension expression.

       size, s
	   Set the video size. For the syntax of this option, check the "Video
	   size" section in the ffmpeg-utils manual.

       dither, d
	   Set the dither type.

	   Possible values are:

	   none
	   ordered
	   random
	   error_diffusion

	   Default is none.

       filter, f
	   Set the resize filter type.

	   Possible values are:

	   point
	   bilinear
	   bicubic
	   spline16
	   spline36
	   lanczos

	   Default is bilinear.

       range, r
	   Set the color range.

	   Possible values are:

	   input
	   limited
	   full

	   Default is same as input.

       primaries, p
	   Set the color primaries.

	   Possible values are:

	   input
	   709
	   unspecified
	   170m
	   240m
	   2020

	   Default is same as input.

       transfer, t
	   Set the transfer characteristics.

	   Possible values are:

	   input
	   709
	   unspecified
	   601
	   linear
	   2020_10
	   2020_12
	   smpte2084
	   iec61966-2-1
	   arib-std-b67

	   Default is same as input.

       matrix, m
	   Set the colorspace matrix.

	   Possible value are:

	   input
	   709
	   unspecified
	   470bg
	   170m
	   2020_ncl
	   2020_cl

	   Default is same as input.

       rangein, rin
	   Set the input color range.

	   Possible values are:

	   input
	   limited
	   full

	   Default is same as input.

       primariesin, pin
	   Set the input color primaries.

	   Possible values are:

	   input
	   709
	   unspecified
	   170m
	   240m
	   2020

	   Default is same as input.

       transferin, tin
	   Set the input transfer characteristics.

	   Possible values are:

	   input
	   709
	   unspecified
	   601
	   linear
	   2020_10
	   2020_12

	   Default is same as input.

       matrixin, min
	   Set the input colorspace matrix.

	   Possible value are:

	   input
	   709
	   unspecified
	   470bg
	   170m
	   2020_ncl
	   2020_cl
       chromal, c
	   Set the output chroma location.

	   Possible values are:

	   input
	   left
	   center
	   topleft
	   top
	   bottomleft
	   bottom
       chromalin, cin
	   Set the input chroma location.

	   Possible values are:

	   input
	   left
	   center
	   topleft
	   top
	   bottomleft
	   bottom
       npl Set the nominal peak luminance.

       The values of the w and h options are expressions containing the
       following constants:

       in_w
       in_h
	   The input width and height

       iw
       ih  These are the same as in_w and in_h.

       out_w
       out_h
	   The output (scaled) width and height

       ow
       oh  These are the same as out_w and out_h

       a   The same as iw / ih

       sar input sample aspect ratio

       dar The input display aspect ratio. Calculated from "(iw / ih) * sar".

       hsub
       vsub
	   horizontal and vertical input chroma subsample values. For example
	   for the pixel format "yuv422p" hsub is 2 and vsub is 1.

       ohsub
       ovsub
	   horizontal and vertical output chroma subsample values. For example
	   for the pixel format "yuv422p" hsub is 2 and vsub is 1.

VIDEO SOURCES
       Below is a description of the currently available video sources.

   buffer
       Buffer video frames, and make them available to the filter chain.

       This source is mainly intended for a programmatic use, in particular
       through the interface defined in libavfilter/vsrc_buffer.h.

       It accepts the following parameters:

       video_size
	   Specify the size (width and height) of the buffered video frames.
	   For the syntax of this option, check the "Video size" section in
	   the ffmpeg-utils manual.

       width
	   The input video width.

       height
	   The input video height.

       pix_fmt
	   A string representing the pixel format of the buffered video
	   frames.  It may be a number corresponding to a pixel format, or a
	   pixel format name.

       time_base
	   Specify the timebase assumed by the timestamps of the buffered
	   frames.

       frame_rate
	   Specify the frame rate expected for the video stream.

       pixel_aspect, sar
	   The sample (pixel) aspect ratio of the input video.

       sws_param
	   Specify the optional parameters to be used for the scale filter
	   which is automatically inserted when an input change is detected in
	   the input size or format.

       hw_frames_ctx
	   When using a hardware pixel format, this should be a reference to
	   an AVHWFramesContext describing input frames.

       For example:

	       buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1

       will instruct the source to accept video frames with size 320x240 and
       with format "yuv410p", assuming 1/24 as the timestamps timebase and
       square pixels (1:1 sample aspect ratio).  Since the pixel format with
       name "yuv410p" corresponds to the number 6 (check the enum
       AVPixelFormat definition in libavutil/pixfmt.h), this example
       corresponds to:

	       buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1

       Alternatively, the options can be specified as a flat string, but this
       syntax is deprecated:

       width:height:pix_fmt:time_base.num:time_base.den:pixel_aspect.num:pixel_aspect.den[:sws_param]

   cellauto
       Create a pattern generated by an elementary cellular automaton.

       The initial state of the cellular automaton can be defined through the
       filename and pattern options. If such options are not specified an
       initial state is created randomly.

       At each new frame a new row in the video is filled with the result of
       the cellular automaton next generation. The behavior when the whole
       frame is filled is defined by the scroll option.

       This source accepts the following options:

       filename, f
	   Read the initial cellular automaton state, i.e. the starting row,
	   from the specified file.  In the file, each non-whitespace
	   character is considered an alive cell, a newline will terminate the
	   row, and further characters in the file will be ignored.

       pattern, p
	   Read the initial cellular automaton state, i.e. the starting row,
	   from the specified string.

	   Each non-whitespace character in the string is considered an alive
	   cell, a newline will terminate the row, and further characters in
	   the string will be ignored.

       rate, r
	   Set the video rate, that is the number of frames generated per
	   second.  Default is 25.

       random_fill_ratio, ratio
	   Set the random fill ratio for the initial cellular automaton row.
	   It is a floating point number value ranging from 0 to 1, defaults
	   to 1/PHI.

	   This option is ignored when a file or a pattern is specified.

       random_seed, seed
	   Set the seed for filling randomly the initial row, must be an
	   integer included between 0 and UINT32_MAX. If not specified, or if
	   explicitly set to -1, the filter will try to use a good random seed
	   on a best effort basis.

       rule
	   Set the cellular automaton rule, it is a number ranging from 0 to
	   255.  Default value is 110.

       size, s
	   Set the size of the output video. For the syntax of this option,
	   check the "Video size" section in the ffmpeg-utils manual.

	   If filename or pattern is specified, the size is set by default to
	   the width of the specified initial state row, and the height is set
	   to width * PHI.

	   If size is set, it must contain the width of the specified pattern
	   string, and the specified pattern will be centered in the larger
	   row.

	   If a filename or a pattern string is not specified, the size value
	   defaults to "320x518" (used for a randomly generated initial
	   state).

       scroll
	   If set to 1, scroll the output upward when all the rows in the
	   output have been already filled. If set to 0, the new generated row
	   will be written over the top row just after the bottom row is
	   filled.  Defaults to 1.

       start_full, full
	   If set to 1, completely fill the output with generated rows before
	   outputting the first frame.	This is the default behavior, for
	   disabling set the value to 0.

       stitch
	   If set to 1, stitch the left and right row edges together.  This is
	   the default behavior, for disabling set the value to 0.

       Examples

       ·   Read the initial state from pattern, and specify an output of size
	   200x400.

		   cellauto=f=pattern:s=200x400

       ·   Generate a random initial row with a width of 200 cells, with a
	   fill ratio of 2/3:

		   cellauto=ratio=2/3:s=200x200

       ·   Create a pattern generated by rule 18 starting by a single alive
	   cell centered on an initial row with width 100:

		   cellauto=p=@s=100x400:full=0:rule=18

       ·   Specify a more elaborated initial pattern:

		   cellauto=p='@@ @ @@':s=100x400:full=0:rule=18

   coreimagesrc
       Video source generated on GPU using Apple's CoreImage API on OSX.

       This video source is a specialized version of the coreimage video
       filter.	Use a core image generator at the beginning of the applied
       filterchain to generate the content.

       The coreimagesrc video source accepts the following options:

       list_generators
	   List all available generators along with all their respective
	   options as well as possible minimum and maximum values along with
	   the default values.

		   list_generators=true

       size, s
	   Specify the size of the sourced video. For the syntax of this
	   option, check the "Video size" section in the ffmpeg-utils manual.
	   The default value is "320x240".

       rate, r
	   Specify the frame rate of the sourced video, as the number of
	   frames generated per second. It has to be a string in the format
	   frame_rate_num/frame_rate_den, an integer number, a floating point
	   number or a valid video frame rate abbreviation. The default value
	   is "25".

       sar Set the sample aspect ratio of the sourced video.

       duration, d
	   Set the duration of the sourced video. See the Time duration
	   section in the ffmpeg-utils(1) manual for the accepted syntax.

	   If not specified, or the expressed duration is negative, the video
	   is supposed to be generated forever.

       Additionally, all options of the coreimage video filter are accepted.
       A complete filterchain can be used for further processing of the
       generated input without CPU-HOST transfer. See coreimage documentation
       and examples for details.

       Examples

       ·   Use CIQRCodeGenerator to create a QR code for the FFmpeg homepage,
	   given as complete and escaped command-line for Apple's standard
	   bash shell:

		   ffmpeg -f lavfi -i coreimagesrc=s=100x100:filter=CIQRCodeGenerator@inputMessage=https\\\\\://FFmpeg.org/@inputCorrectionLevel=H -frames:v 1 QRCode.png

	   This example is equivalent to the QRCode example of coreimage
	   without the need for a nullsrc video source.

   mandelbrot
       Generate a Mandelbrot set fractal, and progressively zoom towards the
       point specified with start_x and start_y.

       This source accepts the following options:

       end_pts
	   Set the terminal pts value. Default value is 400.

       end_scale
	   Set the terminal scale value.  Must be a floating point value.
	   Default value is 0.3.

       inner
	   Set the inner coloring mode, that is the algorithm used to draw the
	   Mandelbrot fractal internal region.

	   It shall assume one of the following values:

	   black
	       Set black mode.

	   convergence
	       Show time until convergence.

	   mincol
	       Set color based on point closest to the origin of the
	       iterations.

	   period
	       Set period mode.

	   Default value is mincol.

       bailout
	   Set the bailout value. Default value is 10.0.

       maxiter
	   Set the maximum of iterations performed by the rendering algorithm.
	   Default value is 7189.

       outer
	   Set outer coloring mode.  It shall assume one of following values:

	   iteration_count
	       Set iteration cound mode.

	   normalized_iteration_count
	       set normalized iteration count mode.

	   Default value is normalized_iteration_count.

       rate, r
	   Set frame rate, expressed as number of frames per second. Default
	   value is "25".

       size, s
	   Set frame size. For the syntax of this option, check the "Video
	   size" section in the ffmpeg-utils manual. Default value is
	   "640x480".

       start_scale
	   Set the initial scale value. Default value is 3.0.

       start_x
	   Set the initial x position. Must be a floating point value between
	   -100 and 100. Default value is
	   -0.743643887037158704752191506114774.

       start_y
	   Set the initial y position. Must be a floating point value between
	   -100 and 100. Default value is
	   -0.131825904205311970493132056385139.

   mptestsrc
       Generate various test patterns, as generated by the MPlayer test
       filter.

       The size of the generated video is fixed, and is 256x256.  This source
       is useful in particular for testing encoding features.

       This source accepts the following options:

       rate, r
	   Specify the frame rate of the sourced video, as the number of
	   frames generated per second. It has to be a string in the format
	   frame_rate_num/frame_rate_den, an integer number, a floating point
	   number or a valid video frame rate abbreviation. The default value
	   is "25".

       duration, d
	   Set the duration of the sourced video. See the Time duration
	   section in the ffmpeg-utils(1) manual for the accepted syntax.

	   If not specified, or the expressed duration is negative, the video
	   is supposed to be generated forever.

       test, t
	   Set the number or the name of the test to perform. Supported tests
	   are:

	   dc_luma
	   dc_chroma
	   freq_luma
	   freq_chroma
	   amp_luma
	   amp_chroma
	   cbp
	   mv
	   ring1
	   ring2
	   all

	   Default value is "all", which will cycle through the list of all
	   tests.

       Some examples:

	       mptestsrc=t=dc_luma

       will generate a "dc_luma" test pattern.

   frei0r_src
       Provide a frei0r source.

       To enable compilation of this filter you need to install the frei0r
       header and configure FFmpeg with "--enable-frei0r".

       This source accepts the following parameters:

       size
	   The size of the video to generate. For the syntax of this option,
	   check the "Video size" section in the ffmpeg-utils manual.

       framerate
	   The framerate of the generated video. It may be a string of the
	   form num/den or a frame rate abbreviation.

       filter_name
	   The name to the frei0r source to load. For more information
	   regarding frei0r and how to set the parameters, read the frei0r
	   section in the video filters documentation.

       filter_params
	   A '|'-separated list of parameters to pass to the frei0r source.

       For example, to generate a frei0r partik0l source with size 200x200 and
       frame rate 10 which is overlaid on the overlay filter main input:

	       frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay

   life
       Generate a life pattern.

       This source is based on a generalization of John Conway's life game.

       The sourced input represents a life grid, each pixel represents a cell
       which can be in one of two possible states, alive or dead. Every cell
       interacts with its eight neighbours, which are the cells that are
       horizontally, vertically, or diagonally adjacent.

       At each interaction the grid evolves according to the adopted rule,
       which specifies the number of neighbor alive cells which will make a
       cell stay alive or born. The rule option allows one to specify the rule
       to adopt.

       This source accepts the following options:

       filename, f
	   Set the file from which to read the initial grid state. In the
	   file, each non-whitespace character is considered an alive cell,
	   and newline is used to delimit the end of each row.

	   If this option is not specified, the initial grid is generated
	   randomly.

       rate, r
	   Set the video rate, that is the number of frames generated per
	   second.  Default is 25.

       random_fill_ratio, ratio
	   Set the random fill ratio for the initial random grid. It is a
	   floating point number value ranging from 0 to 1, defaults to 1/PHI.
	   It is ignored when a file is specified.

       random_seed, seed
	   Set the seed for filling the initial random grid, must be an
	   integer included between 0 and UINT32_MAX. If not specified, or if
	   explicitly set to -1, the filter will try to use a good random seed
	   on a best effort basis.

       rule
	   Set the life rule.

	   A rule can be specified with a code of the kind "SNS/BNB", where NS
	   and NB are sequences of numbers in the range 0-8, NS specifies the
	   number of alive neighbor cells which make a live cell stay alive,
	   and NB the number of alive neighbor cells which make a dead cell to
	   become alive (i.e. to "born").  "s" and "b" can be used in place of
	   "S" and "B", respectively.

	   Alternatively a rule can be specified by an 18-bits integer. The 9
	   high order bits are used to encode the next cell state if it is
	   alive for each number of neighbor alive cells, the low order bits
	   specify the rule for "borning" new cells. Higher order bits encode
	   for an higher number of neighbor cells.  For example the number
	   6153 = "(12<<9)+9" specifies a stay alive rule of 12 and a born
	   rule of 9, which corresponds to "S23/B03".

	   Default value is "S23/B3", which is the original Conway's game of
	   life rule, and will keep a cell alive if it has 2 or 3 neighbor
	   alive cells, and will born a new cell if there are three alive
	   cells around a dead cell.

       size, s
	   Set the size of the output video. For the syntax of this option,
	   check the "Video size" section in the ffmpeg-utils manual.

	   If filename is specified, the size is set by default to the same
	   size of the input file. If size is set, it must contain the size
	   specified in the input file, and the initial grid defined in that
	   file is centered in the larger resulting area.

	   If a filename is not specified, the size value defaults to
	   "320x240" (used for a randomly generated initial grid).

       stitch
	   If set to 1, stitch the left and right grid edges together, and the
	   top and bottom edges also. Defaults to 1.

       mold
	   Set cell mold speed. If set, a dead cell will go from death_color
	   to mold_color with a step of mold. mold can have a value from 0 to
	   255.

       life_color
	   Set the color of living (or new born) cells.

       death_color
	   Set the color of dead cells. If mold is set, this is the first
	   color used to represent a dead cell.

       mold_color
	   Set mold color, for definitely dead and moldy cells.

	   For the syntax of these 3 color options, check the "Color" section
	   in the ffmpeg-utils manual.

       Examples

       ·   Read a grid from pattern, and center it on a grid of size 300x300
	   pixels:

		   life=f=pattern:s=300x300

       ·   Generate a random grid of size 200x200, with a fill ratio of 2/3:

		   life=ratio=2/3:s=200x200

       ·   Specify a custom rule for evolving a randomly generated grid:

		   life=rule=S14/B34

       ·   Full example with slow death effect (mold) using ffplay:

		   ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16

   allrgb, allyuv, color, haldclutsrc, nullsrc, pal75bars, pal100bars,
       rgbtestsrc, smptebars, smptehdbars, testsrc, testsrc2, yuvtestsrc
       The "allrgb" source returns frames of size 4096x4096 of all rgb colors.

       The "allyuv" source returns frames of size 4096x4096 of all yuv colors.

       The "color" source provides an uniformly colored input.

       The "haldclutsrc" source provides an identity Hald CLUT. See also
       haldclut filter.

       The "nullsrc" source returns unprocessed video frames. It is mainly
       useful to be employed in analysis / debugging tools, or as the source
       for filters which ignore the input data.

       The "pal75bars" source generates a color bars pattern, based on EBU PAL
       recommendations with 75% color levels.

       The "pal100bars" source generates a color bars pattern, based on EBU
       PAL recommendations with 100% color levels.

       The "rgbtestsrc" source generates an RGB test pattern useful for
       detecting RGB vs BGR issues. You should see a red, green and blue
       stripe from top to bottom.

       The "smptebars" source generates a color bars pattern, based on the
       SMPTE Engineering Guideline EG 1-1990.

       The "smptehdbars" source generates a color bars pattern, based on the
       SMPTE RP 219-2002.

       The "testsrc" source generates a test video pattern, showing a color
       pattern, a scrolling gradient and a timestamp. This is mainly intended
       for testing purposes.

       The "testsrc2" source is similar to testsrc, but supports more pixel
       formats instead of just "rgb24". This allows using it as an input for
       other tests without requiring a format conversion.

       The "yuvtestsrc" source generates an YUV test pattern. You should see a
       y, cb and cr stripe from top to bottom.

       The sources accept the following parameters:

       level
	   Specify the level of the Hald CLUT, only available in the
	   "haldclutsrc" source. A level of "N" generates a picture of "N*N*N"
	   by "N*N*N" pixels to be used as identity matrix for 3D lookup
	   tables. Each component is coded on a "1/(N*N)" scale.

       color, c
	   Specify the color of the source, only available in the "color"
	   source. For the syntax of this option, check the "Color" section in
	   the ffmpeg-utils manual.

       size, s
	   Specify the size of the sourced video. For the syntax of this
	   option, check the "Video size" section in the ffmpeg-utils manual.
	   The default value is "320x240".

	   This option is not available with the "allrgb", "allyuv", and
	   "haldclutsrc" filters.

       rate, r
	   Specify the frame rate of the sourced video, as the number of
	   frames generated per second. It has to be a string in the format
	   frame_rate_num/frame_rate_den, an integer number, a floating point
	   number or a valid video frame rate abbreviation. The default value
	   is "25".

       duration, d
	   Set the duration of the sourced video. See the Time duration
	   section in the ffmpeg-utils(1) manual for the accepted syntax.

	   If not specified, or the expressed duration is negative, the video
	   is supposed to be generated forever.

       sar Set the sample aspect ratio of the sourced video.

       alpha
	   Specify the alpha (opacity) of the background, only available in
	   the "testsrc2" source. The value must be between 0 (fully
	   transparent) and 255 (fully opaque, the default).

       decimals, n
	   Set the number of decimals to show in the timestamp, only available
	   in the "testsrc" source.

	   The displayed timestamp value will correspond to the original
	   timestamp value multiplied by the power of 10 of the specified
	   value. Default value is 0.

       Examples

       ·   Generate a video with a duration of 5.3 seconds, with size 176x144
	   and a frame rate of 10 frames per second:

		   testsrc=duration=5.3:size=qcif:rate=10

       ·   The following graph description will generate a red source with an
	   opacity of 0.2, with size "qcif" and a frame rate of 10 frames per
	   second:

		   color=c=red@0.2:s=qcif:r=10

       ·   If the input content is to be ignored, "nullsrc" can be used. The
	   following command generates noise in the luminance plane by
	   employing the "geq" filter:

		   nullsrc=s=256x256, geq=random(1)*255:128:128

       Commands

       The "color" source supports the following commands:

       c, color
	   Set the color of the created image. Accepts the same syntax of the
	   corresponding color option.

   openclsrc
       Generate video using an OpenCL program.

       source
	   OpenCL program source file.

       kernel
	   Kernel name in program.

       size, s
	   Size of frames to generate.	This must be set.

       format
	   Pixel format to use for the generated frames.  This must be set.

       rate, r
	   Number of frames generated every second.  Default value is '25'.

       For details of how the program loading works, see the program_opencl
       filter.

       Example programs:

       ·   Generate a colour ramp by setting pixel values from the position of
	   the pixel in the output image.  (Note that this will work with all
	   pixel formats, but the generated output will not be the same.)

		   __kernel void ramp(__write_only image2d_t dst,
				      unsigned int index)
		   {
		       int2 loc = (int2)(get_global_id(0), get_global_id(1));

		       float4 val;
		       val.xy = val.zw = convert_float2(loc) / convert_float2(get_image_dim(dst));

		       write_imagef(dst, loc, val);
		   }

       ·   Generate a Sierpinski carpet pattern, panning by a single pixel
	   each frame.

		   __kernel void sierpinski_carpet(__write_only image2d_t dst,
						   unsigned int index)
		   {
		       int2 loc = (int2)(get_global_id(0), get_global_id(1));

		       float4 value = 0.0f;
		       int x = loc.x + index;
		       int y = loc.y + index;
		       while (x > 0 || y > 0) {
			   if (x % 3 == 1 && y % 3 == 1) {
			       value = 1.0f;
			       break;
			   }
			   x /= 3;
			   y /= 3;
		       }

		       write_imagef(dst, loc, value);
		   }

VIDEO SINKS
       Below is a description of the currently available video sinks.

   buffersink
       Buffer video frames, and make them available to the end of the filter
       graph.

       This sink is mainly intended for programmatic use, in particular
       through the interface defined in libavfilter/buffersink.h or the
       options system.

       It accepts a pointer to an AVBufferSinkContext structure, which defines
       the incoming buffers' formats, to be passed as the opaque parameter to
       "avfilter_init_filter" for initialization.

   nullsink
       Null video sink: do absolutely nothing with the input video. It is
       mainly useful as a template and for use in analysis / debugging tools.

MULTIMEDIA FILTERS
       Below is a description of the currently available multimedia filters.

   abitscope
       Convert input audio to a video output, displaying the audio bit scope.

       The filter accepts the following options:

       rate, r
	   Set frame rate, expressed as number of frames per second. Default
	   value is "25".

       size, s
	   Specify the video size for the output. For the syntax of this
	   option, check the "Video size" section in the ffmpeg-utils manual.
	   Default value is "1024x256".

       colors
	   Specify list of colors separated by space or by '|' which will be
	   used to draw channels. Unrecognized or missing colors will be
	   replaced by white color.

   ahistogram
       Convert input audio to a video output, displaying the volume histogram.

       The filter accepts the following options:

       dmode
	   Specify how histogram is calculated.

	   It accepts the following values:

	   single
	       Use single histogram for all channels.

	   separate
	       Use separate histogram for each channel.

	   Default is "single".

       rate, r
	   Set frame rate, expressed as number of frames per second. Default
	   value is "25".

       size, s
	   Specify the video size for the output. For the syntax of this
	   option, check the "Video size" section in the ffmpeg-utils manual.
	   Default value is "hd720".

       scale
	   Set display scale.

	   It accepts the following values:

	   log logarithmic

	   sqrt
	       square root

	   cbrt
	       cubic root

	   lin linear

	   rlog
	       reverse logarithmic

	   Default is "log".

       ascale
	   Set amplitude scale.

	   It accepts the following values:

	   log logarithmic

	   lin linear

	   Default is "log".

       acount
	   Set how much frames to accumulate in histogram.  Defauls is 1.
	   Setting this to -1 accumulates all frames.

       rheight
	   Set histogram ratio of window height.

       slide
	   Set sonogram sliding.

	   It accepts the following values:

	   replace
	       replace old rows with new ones.

	   scroll
	       scroll from top to bottom.

	   Default is "replace".

   aphasemeter
       Measures phase of input audio, which is exported as metadata
       "lavfi.aphasemeter.phase", representing mean phase of current audio
       frame. A video output can also be produced and is enabled by default.
       The audio is passed through as first output.

       Audio will be rematrixed to stereo if it has a different channel
       layout. Phase value is in range "[-1, 1]" where "-1" means left and
       right channels are completely out of phase and 1 means channels are in
       phase.

       The filter accepts the following options, all related to its video
       output:

       rate, r
	   Set the output frame rate. Default value is 25.

       size, s
	   Set the video size for the output. For the syntax of this option,
	   check the "Video size" section in the ffmpeg-utils manual.  Default
	   value is "800x400".

       rc
       gc
       bc  Specify the red, green, blue contrast. Default values are 2, 7 and
	   1.  Allowed range is "[0, 255]".

       mpc Set color which will be used for drawing median phase. If color is
	   "none" which is default, no median phase value will be drawn.

       video
	   Enable video output. Default is enabled.

   avectorscope
       Convert input audio to a video output, representing the audio vector
       scope.

       The filter is used to measure the difference between channels of stereo
       audio stream. A monoaural signal, consisting of identical left and
       right signal, results in straight vertical line. Any stereo separation
       is visible as a deviation from this line, creating a Lissajous figure.
       If the straight (or deviation from it) but horizontal line appears this
       indicates that the left and right channels are out of phase.

       The filter accepts the following options:

       mode, m
	   Set the vectorscope mode.

	   Available values are:

	   lissajous
	       Lissajous rotated by 45 degrees.

	   lissajous_xy
	       Same as above but not rotated.

	   polar
	       Shape resembling half of circle.

	   Default value is lissajous.

       size, s
	   Set the video size for the output. For the syntax of this option,
	   check the "Video size" section in the ffmpeg-utils manual.  Default
	   value is "400x400".

       rate, r
	   Set the output frame rate. Default value is 25.

       rc
       gc
       bc
       ac  Specify the red, green, blue and alpha contrast. Default values are
	   40, 160, 80 and 255.  Allowed range is "[0, 255]".

       rf
       gf
       bf
       af  Specify the red, green, blue and alpha fade. Default values are 15,
	   10, 5 and 5.  Allowed range is "[0, 255]".

       zoom
	   Set the zoom factor. Default value is 1. Allowed range is "[0,
	   10]".  Values lower than 1 will auto adjust zoom factor to maximal
	   possible value.

       draw
	   Set the vectorscope drawing mode.

	   Available values are:

	   dot Draw dot for each sample.

	   line
	       Draw line between previous and current sample.

	   Default value is dot.

       scale
	   Specify amplitude scale of audio samples.

	   Available values are:

	   lin Linear.

	   sqrt
	       Square root.

	   cbrt
	       Cubic root.

	   log Logarithmic.

       swap
	   Swap left channel axis with right channel axis.

       mirror
	   Mirror axis.

	   none
	       No mirror.

	   x   Mirror only x axis.

	   y   Mirror only y axis.

	   xy  Mirror both axis.

       Examples

       ·   Complete example using ffplay:

		   ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
				[a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'

   bench, abench
       Benchmark part of a filtergraph.

       The filter accepts the following options:

       action
	   Start or stop a timer.

	   Available values are:

	   start
	       Get the current time, set it as frame metadata (using the key
	       "lavfi.bench.start_time"), and forward the frame to the next
	       filter.

	   stop
	       Get the current time and fetch the "lavfi.bench.start_time"
	       metadata from the input frame metadata to get the time
	       difference. Time difference, average, maximum and minimum time
	       (respectively "t", "avg", "max" and "min") are then printed.
	       The timestamps are expressed in seconds.

       Examples

       ·   Benchmark selectivecolor filter:

		   bench=start,selectivecolor=reds=-.2 .12 -.49,bench=stop

   concat
       Concatenate audio and video streams, joining them together one after
       the other.

       The filter works on segments of synchronized video and audio streams.
       All segments must have the same number of streams of each type, and
       that will also be the number of streams at output.

       The filter accepts the following options:

       n   Set the number of segments. Default is 2.

       v   Set the number of output video streams, that is also the number of
	   video streams in each segment. Default is 1.

       a   Set the number of output audio streams, that is also the number of
	   audio streams in each segment. Default is 0.

       unsafe
	   Activate unsafe mode: do not fail if segments have a different
	   format.

       The filter has v+a outputs: first v video outputs, then a audio
       outputs.

       There are nx(v+a) inputs: first the inputs for the first segment, in
       the same order as the outputs, then the inputs for the second segment,
       etc.

       Related streams do not always have exactly the same duration, for
       various reasons including codec frame size or sloppy authoring. For
       that reason, related synchronized streams (e.g. a video and its audio
       track) should be concatenated at once. The concat filter will use the
       duration of the longest stream in each segment (except the last one),
       and if necessary pad shorter audio streams with silence.

       For this filter to work correctly, all segments must start at timestamp
       0.

       All corresponding streams must have the same parameters in all
       segments; the filtering system will automatically select a common pixel
       format for video streams, and a common sample format, sample rate and
       channel layout for audio streams, but other settings, such as
       resolution, must be converted explicitly by the user.

       Different frame rates are acceptable but will result in variable frame
       rate at output; be sure to configure the output file to handle it.

       Examples

       ·   Concatenate an opening, an episode and an ending, all in bilingual
	   version (video in stream 0, audio in streams 1 and 2):

		   ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
		     '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
		      concat=n=3:v=1:a=2 [v] [a1] [a2]' \
		     -map '[v]' -map '[a1]' -map '[a2]' output.mkv

       ·   Concatenate two parts, handling audio and video separately, using
	   the (a)movie sources, and adjusting the resolution:

		   movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
		   movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
		   [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]

	   Note that a desync will happen at the stitch if the audio and video
	   streams do not have exactly the same duration in the first file.

       Commands

       This filter supports the following commands:

       next
	   Close the current segment and step to the next one

   drawgraph, adrawgraph
       Draw a graph using input video or audio metadata.

       It accepts the following parameters:

       m1  Set 1st frame metadata key from which metadata values will be used
	   to draw a graph.

       fg1 Set 1st foreground color expression.

       m2  Set 2nd frame metadata key from which metadata values will be used
	   to draw a graph.

       fg2 Set 2nd foreground color expression.

       m3  Set 3rd frame metadata key from which metadata values will be used
	   to draw a graph.

       fg3 Set 3rd foreground color expression.

       m4  Set 4th frame metadata key from which metadata values will be used
	   to draw a graph.

       fg4 Set 4th foreground color expression.

       min Set minimal value of metadata value.

       max Set maximal value of metadata value.

       bg  Set graph background color. Default is white.

       mode
	   Set graph mode.

	   Available values for mode is:

	   bar
	   dot
	   line

	   Default is "line".

       slide
	   Set slide mode.

	   Available values for slide is:

	   frame
	       Draw new frame when right border is reached.

	   replace
	       Replace old columns with new ones.

	   scroll
	       Scroll from right to left.

	   rscroll
	       Scroll from left to right.

	   picture
	       Draw single picture.

	   Default is "frame".

       size
	   Set size of graph video. For the syntax of this option, check the
	   "Video size" section in the ffmpeg-utils manual.  The default value
	   is "900x256".

	   The foreground color expressions can use the following variables:

	   MIN Minimal value of metadata value.

	   MAX Maximal value of metadata value.

	   VAL Current metadata key value.

	   The color is defined as 0xAABBGGRR.

       Example using metadata from signalstats filter:

	       signalstats,drawgraph=lavfi.signalstats.YAVG:min=0:max=255

       Example using metadata from ebur128 filter:

	       ebur128=metadata=1,adrawgraph=lavfi.r128.M:min=-120:max=5

   ebur128
       EBU R128 scanner filter. This filter takes an audio stream as input and
       outputs it unchanged. By default, it logs a message at a frequency of
       10Hz with the Momentary loudness (identified by "M"), Short-term
       loudness ("S"), Integrated loudness ("I") and Loudness Range ("LRA").

       The filter also has a video output (see the video option) with a real
       time graph to observe the loudness evolution. The graphic contains the
       logged message mentioned above, so it is not printed anymore when this
       option is set, unless the verbose logging is set. The main graphing
       area contains the short-term loudness (3 seconds of analysis), and the
       gauge on the right is for the momentary loudness (400 milliseconds).

       More information about the Loudness Recommendation EBU R128 on
       <http://tech.ebu.ch/loudness>.

       The filter accepts the following options:

       video
	   Activate the video output. The audio stream is passed unchanged
	   whether this option is set or no. The video stream will be the
	   first output stream if activated. Default is 0.

       size
	   Set the video size. This option is for video only. For the syntax
	   of this option, check the "Video size" section in the ffmpeg-utils
	   manual.  Default and minimum resolution is "640x480".

       meter
	   Set the EBU scale meter. Default is 9. Common values are 9 and 18,
	   respectively for EBU scale meter +9 and EBU scale meter +18. Any
	   other integer value between this range is allowed.

       metadata
	   Set metadata injection. If set to 1, the audio input will be
	   segmented into 100ms output frames, each of them containing various
	   loudness information in metadata.  All the metadata keys are
	   prefixed with "lavfi.r128.".

	   Default is 0.

       framelog
	   Force the frame logging level.

	   Available values are:

	   info
	       information logging level

	   verbose
	       verbose logging level

	   By default, the logging level is set to info. If the video or the
	   metadata options are set, it switches to verbose.

       peak
	   Set peak mode(s).

	   Available modes can be cumulated (the option is a "flag" type).
	   Possible values are:

	   none
	       Disable any peak mode (default).

	   sample
	       Enable sample-peak mode.

	       Simple peak mode looking for the higher sample value. It logs a
	       message for sample-peak (identified by "SPK").

	   true
	       Enable true-peak mode.

	       If enabled, the peak lookup is done on an over-sampled version
	       of the input stream for better peak accuracy. It logs a message
	       for true-peak.  (identified by "TPK") and true-peak per frame
	       (identified by "FTPK").	This mode requires a build with
	       "libswresample".

       dualmono
	   Treat mono input files as "dual mono". If a mono file is intended
	   for playback on a stereo system, its EBU R128 measurement will be
	   perceptually incorrect.  If set to "true", this option will
	   compensate for this effect.	Multi-channel input files are not
	   affected by this option.

       panlaw
	   Set a specific pan law to be used for the measurement of dual mono
	   files.  This parameter is optional, and has a default value of
	   -3.01dB.

       Examples

       ·   Real-time graph using ffplay, with a EBU scale meter +18:

		   ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"

       ·   Run an analysis with ffmpeg:

		   ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -

   interleave, ainterleave
       Temporally interleave frames from several inputs.

       "interleave" works with video inputs, "ainterleave" with audio.

       These filters read frames from several inputs and send the oldest
       queued frame to the output.

       Input streams must have well defined, monotonically increasing frame
       timestamp values.

       In order to submit one frame to output, these filters need to enqueue
       at least one frame for each input, so they cannot work in case one
       input is not yet terminated and will not receive incoming frames.

       For example consider the case when one input is a "select" filter which
       always drops input frames. The "interleave" filter will keep reading
       from that input, but it will never be able to send new frames to output
       until the input sends an end-of-stream signal.

       Also, depending on inputs synchronization, the filters will drop frames
       in case one input receives more frames than the other ones, and the
       queue is already filled.

       These filters accept the following options:

       nb_inputs, n
	   Set the number of different inputs, it is 2 by default.

       Examples

       ·   Interleave frames belonging to different streams using ffmpeg:

		   ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi

       ·   Add flickering blur effect:

		   select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave

   metadata, ametadata
       Manipulate frame metadata.

       This filter accepts the following options:

       mode
	   Set mode of operation of the filter.

	   Can be one of the following:

	   select
	       If both "value" and "key" is set, select frames which have such
	       metadata. If only "key" is set, select every frame that has
	       such key in metadata.

	   add Add new metadata "key" and "value". If key is already available
	       do nothing.

	   modify
	       Modify value of already present key.

	   delete
	       If "value" is set, delete only keys that have such value.
	       Otherwise, delete key. If "key" is not set, delete all metadata
	       values in the frame.

	   print
	       Print key and its value if metadata was found. If "key" is not
	       set print all metadata values available in frame.

       key Set key used with all modes. Must be set for all modes except
	   "print" and "delete".

       value
	   Set metadata value which will be used. This option is mandatory for
	   "modify" and "add" mode.

       function
	   Which function to use when comparing metadata value and "value".

	   Can be one of following:

	   same_str
	       Values are interpreted as strings, returns true if metadata
	       value is same as "value".

	   starts_with
	       Values are interpreted as strings, returns true if metadata
	       value starts with the "value" option string.

	   less
	       Values are interpreted as floats, returns true if metadata
	       value is less than "value".

	   equal
	       Values are interpreted as floats, returns true if "value" is
	       equal with metadata value.

	   greater
	       Values are interpreted as floats, returns true if metadata
	       value is greater than "value".

	   expr
	       Values are interpreted as floats, returns true if expression
	       from option "expr" evaluates to true.

       expr
	   Set expression which is used when "function" is set to "expr".  The
	   expression is evaluated through the eval API and can contain the
	   following constants:

	   VALUE1
	       Float representation of "value" from metadata key.

	   VALUE2
	       Float representation of "value" as supplied by user in "value"
	       option.

       file
	   If specified in "print" mode, output is written to the named file.
	   Instead of plain filename any writable url can be specified.
	   Filename ``-'' is a shorthand for standard output. If "file" option
	   is not set, output is written to the log with AV_LOG_INFO loglevel.

       Examples

       ·   Print all metadata values for frames with key
	   "lavfi.signalstats.YDIF" with values between 0 and 1.

		   signalstats,metadata=print:key=lavfi.signalstats.YDIF:value=0:function=expr:expr='between(VALUE1,0,1)'

       ·   Print silencedetect output to file metadata.txt.

		   silencedetect,ametadata=mode=print:file=metadata.txt

       ·   Direct all metadata to a pipe with file descriptor 4.

		   metadata=mode=print:file='pipe\:4'

   perms, aperms
       Set read/write permissions for the output frames.

       These filters are mainly aimed at developers to test direct path in the
       following filter in the filtergraph.

       The filters accept the following options:

       mode
	   Select the permissions mode.

	   It accepts the following values:

	   none
	       Do nothing. This is the default.

	   ro  Set all the output frames read-only.

	   rw  Set all the output frames directly writable.

	   toggle
	       Make the frame read-only if writable, and writable if read-
	       only.

	   random
	       Set each output frame read-only or writable randomly.

       seed
	   Set the seed for the random mode, must be an integer included
	   between 0 and "UINT32_MAX". If not specified, or if explicitly set
	   to "-1", the filter will try to use a good random seed on a best
	   effort basis.

       Note: in case of auto-inserted filter between the permission filter and
       the following one, the permission might not be received as expected in
       that following filter. Inserting a format or aformat filter before the
       perms/aperms filter can avoid this problem.

   realtime, arealtime
       Slow down filtering to match real time approximately.

       These filters will pause the filtering for a variable amount of time to
       match the output rate with the input timestamps.  They are similar to
       the re option to "ffmpeg".

       They accept the following options:

       limit
	   Time limit for the pauses. Any pause longer than that will be
	   considered a timestamp discontinuity and reset the timer. Default
	   is 2 seconds.

   select, aselect
       Select frames to pass in output.

       This filter accepts the following options:

       expr, e
	   Set expression, which is evaluated for each input frame.

	   If the expression is evaluated to zero, the frame is discarded.

	   If the evaluation result is negative or NaN, the frame is sent to
	   the first output; otherwise it is sent to the output with index
	   "ceil(val)-1", assuming that the input index starts from 0.

	   For example a value of 1.2 corresponds to the output with index
	   "ceil(1.2)-1 = 2-1 = 1", that is the second output.

       outputs, n
	   Set the number of outputs. The output to which to send the selected
	   frame is based on the result of the evaluation. Default value is 1.

       The expression can contain the following constants:

       n   The (sequential) number of the filtered frame, starting from 0.

       selected_n
	   The (sequential) number of the selected frame, starting from 0.

       prev_selected_n
	   The sequential number of the last selected frame. It's NAN if
	   undefined.

       TB  The timebase of the input timestamps.

       pts The PTS (Presentation TimeStamp) of the filtered video frame,
	   expressed in TB units. It's NAN if undefined.

       t   The PTS of the filtered video frame, expressed in seconds. It's NAN
	   if undefined.

       prev_pts
	   The PTS of the previously filtered video frame. It's NAN if
	   undefined.

       prev_selected_pts
	   The PTS of the last previously filtered video frame. It's NAN if
	   undefined.

       prev_selected_t
	   The PTS of the last previously selected video frame, expressed in
	   seconds. It's NAN if undefined.

       start_pts
	   The PTS of the first video frame in the video. It's NAN if
	   undefined.

       start_t
	   The time of the first video frame in the video. It's NAN if
	   undefined.

       pict_type (video only)
	   The type of the filtered frame. It can assume one of the following
	   values:

	   I
	   P
	   B
	   S
	   SI
	   SP
	   BI
       interlace_type (video only)
	   The frame interlace type. It can assume one of the following
	   values:

	   PROGRESSIVE
	       The frame is progressive (not interlaced).

	   TOPFIRST
	       The frame is top-field-first.

	   BOTTOMFIRST
	       The frame is bottom-field-first.

       consumed_sample_n (audio only)
	   the number of selected samples before the current frame

       samples_n (audio only)
	   the number of samples in the current frame

       sample_rate (audio only)
	   the input sample rate

       key This is 1 if the filtered frame is a key-frame, 0 otherwise.

       pos the position in the file of the filtered frame, -1 if the
	   information is not available (e.g. for synthetic video)

       scene (video only)
	   value between 0 and 1 to indicate a new scene; a low value reflects
	   a low probability for the current frame to introduce a new scene,
	   while a higher value means the current frame is more likely to be
	   one (see the example below)

       concatdec_select
	   The concat demuxer can select only part of a concat input file by
	   setting an inpoint and an outpoint, but the output packets may not
	   be entirely contained in the selected interval. By using this
	   variable, it is possible to skip frames generated by the concat
	   demuxer which are not exactly contained in the selected interval.

	   This works by comparing the frame pts against the
	   lavf.concat.start_time and the lavf.concat.duration packet metadata
	   values which are also present in the decoded frames.

	   The concatdec_select variable is -1 if the frame pts is at least
	   start_time and either the duration metadata is missing or the frame
	   pts is less than start_time + duration, 0 otherwise, and NaN if the
	   start_time metadata is missing.

	   That basically means that an input frame is selected if its pts is
	   within the interval set by the concat demuxer.

       The default value of the select expression is "1".

       Examples

       ·   Select all frames in input:

		   select

	   The example above is the same as:

		   select=1

       ·   Skip all frames:

		   select=0

       ·   Select only I-frames:

		   select='eq(pict_type\,I)'

       ·   Select one frame every 100:

		   select='not(mod(n\,100))'

       ·   Select only frames contained in the 10-20 time interval:

		   select=between(t\,10\,20)

       ·   Select only I-frames contained in the 10-20 time interval:

		   select=between(t\,10\,20)*eq(pict_type\,I)

       ·   Select frames with a minimum distance of 10 seconds:

		   select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'

       ·   Use aselect to select only audio frames with samples number > 100:

		   aselect='gt(samples_n\,100)'

       ·   Create a mosaic of the first scenes:

		   ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png

	   Comparing scene against a value between 0.3 and 0.5 is generally a
	   sane choice.

       ·   Send even and odd frames to separate outputs, and compose them:

		   select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h

       ·   Select useful frames from an ffconcat file which is using inpoints
	   and outpoints but where the source files are not intra frame only.

		   ffmpeg -copyts -vsync 0 -segment_time_metadata 1 -i input.ffconcat -vf select=concatdec_select -af aselect=concatdec_select output.avi

   sendcmd, asendcmd
       Send commands to filters in the filtergraph.

       These filters read commands to be sent to other filters in the
       filtergraph.

       "sendcmd" must be inserted between two video filters, "asendcmd" must
       be inserted between two audio filters, but apart from that they act the
       same way.

       The specification of commands can be provided in the filter arguments
       with the commands option, or in a file specified by the filename
       option.

       These filters accept the following options:

       commands, c
	   Set the commands to be read and sent to the other filters.

       filename, f
	   Set the filename of the commands to be read and sent to the other
	   filters.

       Commands syntax

       A commands description consists of a sequence of interval
       specifications, comprising a list of commands to be executed when a
       particular event related to that interval occurs. The occurring event
       is typically the current frame time entering or leaving a given time
       interval.

       An interval is specified by the following syntax:

	       <START>[-<END>] <COMMANDS>;

       The time interval is specified by the START and END times.  END is
       optional and defaults to the maximum time.

       The current frame time is considered within the specified interval if
       it is included in the interval [START, END), that is when the time is
       greater or equal to START and is lesser than END.

       COMMANDS consists of a sequence of one or more command specifications,
       separated by ",", relating to that interval.  The syntax of a command
       specification is given by:

	       [<FLAGS>] <TARGET> <COMMAND> <ARG>

       FLAGS is optional and specifies the type of events relating to the time
       interval which enable sending the specified command, and must be a non-
       null sequence of identifier flags separated by "+" or "|" and enclosed
       between "[" and "]".

       The following flags are recognized:

       enter
	   The command is sent when the current frame timestamp enters the
	   specified interval. In other words, the command is sent when the
	   previous frame timestamp was not in the given interval, and the
	   current is.

       leave
	   The command is sent when the current frame timestamp leaves the
	   specified interval. In other words, the command is sent when the
	   previous frame timestamp was in the given interval, and the current
	   is not.

       If FLAGS is not specified, a default value of "[enter]" is assumed.

       TARGET specifies the target of the command, usually the name of the
       filter class or a specific filter instance name.

       COMMAND specifies the name of the command for the target filter.

       ARG is optional and specifies the optional list of argument for the
       given COMMAND.

       Between one interval specification and another, whitespaces, or
       sequences of characters starting with "#" until the end of line, are
       ignored and can be used to annotate comments.

       A simplified BNF description of the commands specification syntax
       follows:

	       <COMMAND_FLAG>  ::= "enter" | "leave"
	       <COMMAND_FLAGS> ::= <COMMAND_FLAG> [(+|"|")<COMMAND_FLAG>]
	       <COMMAND>       ::= ["[" <COMMAND_FLAGS> "]"] <TARGET> <COMMAND> [<ARG>]
	       <COMMANDS>      ::= <COMMAND> [,<COMMANDS>]
	       <INTERVAL>      ::= <START>[-<END>] <COMMANDS>
	       <INTERVALS>     ::= <INTERVAL>[;<INTERVALS>]

       Examples

       ·   Specify audio tempo change at second 4:

		   asendcmd=c='4.0 atempo tempo 1.5',atempo

       ·   Target a specific filter instance:

		   asendcmd=c='4.0 atempo@my tempo 1.5',atempo@my

       ·   Specify a list of drawtext and hue commands in a file.

		   # show text in the interval 5-10
		   5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
			    [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';

		   # desaturate the image in the interval 15-20
		   15.0-20.0 [enter] hue s 0,
			     [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
			     [leave] hue s 1,
			     [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';

		   # apply an exponential saturation fade-out effect, starting from time 25
		   25 [enter] hue s exp(25-t)

	   A filtergraph allowing to read and process the above command list
	   stored in a file test.cmd, can be specified with:

		   sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue

   setpts, asetpts
       Change the PTS (presentation timestamp) of the input frames.

       "setpts" works on video frames, "asetpts" on audio frames.

       This filter accepts the following options:

       expr
	   The expression which is evaluated for each frame to construct its
	   timestamp.

       The expression is evaluated through the eval API and can contain the
       following constants:

       FRAME_RATE, FR
	   frame rate, only defined for constant frame-rate video

       PTS The presentation timestamp in input

       N   The count of the input frame for video or the number of consumed
	   samples, not including the current frame for audio, starting from
	   0.

       NB_CONSUMED_SAMPLES
	   The number of consumed samples, not including the current frame
	   (only audio)

       NB_SAMPLES, S
	   The number of samples in the current frame (only audio)

       SAMPLE_RATE, SR
	   The audio sample rate.

       STARTPTS
	   The PTS of the first frame.

       STARTT
	   the time in seconds of the first frame

       INTERLACED
	   State whether the current frame is interlaced.

       T   the time in seconds of the current frame

       POS original position in the file of the frame, or undefined if
	   undefined for the current frame

       PREV_INPTS
	   The previous input PTS.

       PREV_INT
	   previous input time in seconds

       PREV_OUTPTS
	   The previous output PTS.

       PREV_OUTT
	   previous output time in seconds

       RTCTIME
	   The wallclock (RTC) time in microseconds. This is deprecated, use
	   time(0) instead.

       RTCSTART
	   The wallclock (RTC) time at the start of the movie in microseconds.

       TB  The timebase of the input timestamps.

       Examples

       ·   Start counting PTS from zero

		   setpts=PTS-STARTPTS

       ·   Apply fast motion effect:

		   setpts=0.5*PTS

       ·   Apply slow motion effect:

		   setpts=2.0*PTS

       ·   Set fixed rate of 25 frames per second:

		   setpts=N/(25*TB)

       ·   Set fixed rate 25 fps with some jitter:

		   setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'

       ·   Apply an offset of 10 seconds to the input PTS:

		   setpts=PTS+10/TB

       ·   Generate timestamps from a "live source" and rebase onto the
	   current timebase:

		   setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'

       ·   Generate timestamps by counting samples:

		   asetpts=N/SR/TB

   setrange
       Force color range for the output video frame.

       The "setrange" filter marks the color range property for the output
       frames. It does not change the input frame, but only sets the
       corresponding property, which affects how the frame is treated by
       following filters.

       The filter accepts the following options:

       range
	   Available values are:

	   auto
	       Keep the same color range property.

	   unspecified, unknown
	       Set the color range as unspecified.

	   limited, tv, mpeg
	       Set the color range as limited.

	   full, pc, jpeg
	       Set the color range as full.

   settb, asettb
       Set the timebase to use for the output frames timestamps.  It is mainly
       useful for testing timebase configuration.

       It accepts the following parameters:

       expr, tb
	   The expression which is evaluated into the output timebase.

       The value for tb is an arithmetic expression representing a rational.
       The expression can contain the constants "AVTB" (the default timebase),
       "intb" (the input timebase) and "sr" (the sample rate, audio only).
       Default value is "intb".

       Examples

       ·   Set the timebase to 1/25:

		   settb=expr=1/25

       ·   Set the timebase to 1/10:

		   settb=expr=0.1

       ·   Set the timebase to 1001/1000:

		   settb=1+0.001

       ·   Set the timebase to 2*intb:

		   settb=2*intb

       ·   Set the default timebase value:

		   settb=AVTB

   showcqt
       Convert input audio to a video output representing frequency spectrum
       logarithmically using Brown-Puckette constant Q transform algorithm
       with direct frequency domain coefficient calculation (but the transform
       itself is not really constant Q, instead the Q factor is actually
       variable/clamped), with musical tone scale, from E0 to D#10.

       The filter accepts the following options:

       size, s
	   Specify the video size for the output. It must be even. For the
	   syntax of this option, check the "Video size" section in the
	   ffmpeg-utils manual.  Default value is "1920x1080".

       fps, rate, r
	   Set the output frame rate. Default value is 25.

       bar_h
	   Set the bargraph height. It must be even. Default value is "-1"
	   which computes the bargraph height automatically.

       axis_h
	   Set the axis height. It must be even. Default value is "-1" which
	   computes the axis height automatically.

       sono_h
	   Set the sonogram height. It must be even. Default value is "-1"
	   which computes the sonogram height automatically.

       fullhd
	   Set the fullhd resolution. This option is deprecated, use size, s
	   instead. Default value is 1.

       sono_v, volume
	   Specify the sonogram volume expression. It can contain variables:

	   bar_v
	       the bar_v evaluated expression

	   frequency, freq, f
	       the frequency where it is evaluated

	   timeclamp, tc
	       the value of timeclamp option

	   and functions:

	   a_weighting(f)
	       A-weighting of equal loudness

	   b_weighting(f)
	       B-weighting of equal loudness

	   c_weighting(f)
	       C-weighting of equal loudness.

	   Default value is 16.

       bar_v, volume2
	   Specify the bargraph volume expression. It can contain variables:

	   sono_v
	       the sono_v evaluated expression

	   frequency, freq, f
	       the frequency where it is evaluated

	   timeclamp, tc
	       the value of timeclamp option

	   and functions:

	   a_weighting(f)
	       A-weighting of equal loudness

	   b_weighting(f)
	       B-weighting of equal loudness

	   c_weighting(f)
	       C-weighting of equal loudness.

	   Default value is "sono_v".

       sono_g, gamma
	   Specify the sonogram gamma. Lower gamma makes the spectrum more
	   contrast, higher gamma makes the spectrum having more range.
	   Default value is 3.	Acceptable range is "[1, 7]".

       bar_g, gamma2
	   Specify the bargraph gamma. Default value is 1. Acceptable range is
	   "[1, 7]".

       bar_t
	   Specify the bargraph transparency level. Lower value makes the
	   bargraph sharper.  Default value is 1. Acceptable range is "[0,
	   1]".

       timeclamp, tc
	   Specify the transform timeclamp. At low frequency, there is trade-
	   off between accuracy in time domain and frequency domain. If
	   timeclamp is lower, event in time domain is represented more
	   accurately (such as fast bass drum), otherwise event in frequency
	   domain is represented more accurately (such as bass guitar).
	   Acceptable range is "[0.002, 1]". Default value is 0.17.

       attack
	   Set attack time in seconds. The default is 0 (disabled). Otherwise,
	   it limits future samples by applying asymmetric windowing in time
	   domain, useful when low latency is required. Accepted range is "[0,
	   1]".

       basefreq
	   Specify the transform base frequency. Default value is
	   20.01523126408007475, which is frequency 50 cents below E0.
	   Acceptable range is "[10, 100000]".

       endfreq
	   Specify the transform end frequency. Default value is
	   20495.59681441799654, which is frequency 50 cents above D#10.
	   Acceptable range is "[10, 100000]".

       coeffclamp
	   This option is deprecated and ignored.

       tlength
	   Specify the transform length in time domain. Use this option to
	   control accuracy trade-off between time domain and frequency domain
	   at every frequency sample.  It can contain variables:

	   frequency, freq, f
	       the frequency where it is evaluated

	   timeclamp, tc
	       the value of timeclamp option.

	   Default value is "384*tc/(384+tc*f)".

       count
	   Specify the transform count for every video frame. Default value is
	   6.  Acceptable range is "[1, 30]".

       fcount
	   Specify the transform count for every single pixel. Default value
	   is 0, which makes it computed automatically. Acceptable range is
	   "[0, 10]".

       fontfile
	   Specify font file for use with freetype to draw the axis. If not
	   specified, use embedded font. Note that drawing with font file or
	   embedded font is not implemented with custom basefreq and endfreq,
	   use axisfile option instead.

       font
	   Specify fontconfig pattern. This has lower priority than fontfile.
	   The : in the pattern may be replaced by | to avoid unnecessary
	   escaping.

       fontcolor
	   Specify font color expression. This is arithmetic expression that
	   should return integer value 0xRRGGBB. It can contain variables:

	   frequency, freq, f
	       the frequency where it is evaluated

	   timeclamp, tc
	       the value of timeclamp option

	   and functions:

	   midi(f)
	       midi number of frequency f, some midi numbers: E0(16), C1(24),
	       C2(36), A4(69)

	   r(x), g(x), b(x)
	       red, green, and blue value of intensity x.

	   Default value is "st(0, (midi(f)-59.5)/12); st(1,
	   if(between(ld(0),0,1), 0.5-0.5*cos(2*PI*ld(0)), 0)); r(1-ld(1)) +
	   b(ld(1))".

       axisfile
	   Specify image file to draw the axis. This option override fontfile
	   and fontcolor option.

       axis, text
	   Enable/disable drawing text to the axis. If it is set to 0, drawing
	   to the axis is disabled, ignoring fontfile and axisfile option.
	   Default value is 1.

       csp Set colorspace. The accepted values are:

	   unspecified
	       Unspecified (default)

	   bt709
	       BT.709

	   fcc FCC

	   bt470bg
	       BT.470BG or BT.601-6 625

	   smpte170m
	       SMPTE-170M or BT.601-6 525

	   smpte240m
	       SMPTE-240M

	   bt2020ncl
	       BT.2020 with non-constant luminance

       cscheme
	   Set spectrogram color scheme. This is list of floating point values
	   with format "left_r|left_g|left_b|right_r|right_g|right_b".	The
	   default is "1|0.5|0|0|0.5|1".

       Examples

       ·   Playing audio while showing the spectrum:

		   ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt [out0]'

       ·   Same as above, but with frame rate 30 fps:

		   ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fps=30:count=5 [out0]'

       ·   Playing at 1280x720:

		   ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=s=1280x720:count=4 [out0]'

       ·   Disable sonogram display:

		   sono_h=0

       ·   A1 and its harmonics: A1, A2, (near)E3, A3:

		   ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t),
				    asplit[a][out1]; [a] showcqt [out0]'

       ·   Same as above, but with more accuracy in frequency domain:

		   ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t),
				    asplit[a][out1]; [a] showcqt=timeclamp=0.5 [out0]'

       ·   Custom volume:

		   bar_v=10:sono_v=bar_v*a_weighting(f)

       ·   Custom gamma, now spectrum is linear to the amplitude.

		   bar_g=2:sono_g=2

       ·   Custom tlength equation:

		   tc=0.33:tlength='st(0,0.17); 384*tc / (384 / ld(0) + tc*f /(1-ld(0))) + 384*tc / (tc*f / ld(0) + 384 /(1-ld(0)))'

       ·   Custom fontcolor and fontfile, C-note is colored green, others are
	   colored blue:

		   fontcolor='if(mod(floor(midi(f)+0.5),12), 0x0000FF, g(1))':fontfile=myfont.ttf

       ·   Custom font using fontconfig:

		   font='Courier New,Monospace,mono|bold'

       ·   Custom frequency range with custom axis using image file:

		   axisfile=myaxis.png:basefreq=40:endfreq=10000

   showfreqs
       Convert input audio to video output representing the audio power
       spectrum.  Audio amplitude is on Y-axis while frequency is on X-axis.

       The filter accepts the following options:

       size, s
	   Specify size of video. For the syntax of this option, check the
	   "Video size" section in the ffmpeg-utils manual.  Default is
	   "1024x512".

       mode
	   Set display mode.  This set how each frequency bin will be
	   represented.

	   It accepts the following values:

	   line
	   bar
	   dot

	   Default is "bar".

       ascale
	   Set amplitude scale.

	   It accepts the following values:

	   lin Linear scale.

	   sqrt
	       Square root scale.

	   cbrt
	       Cubic root scale.

	   log Logarithmic scale.

	   Default is "log".

       fscale
	   Set frequency scale.

	   It accepts the following values:

	   lin Linear scale.

	   log Logarithmic scale.

	   rlog
	       Reverse logarithmic scale.

	   Default is "lin".

       win_size
	   Set window size.

	   It accepts the following values:

	   w16
	   w32
	   w64
	   w128
	   w256
	   w512
	   w1024
	   w2048
	   w4096
	   w8192
	   w16384
	   w32768
	   w65536

	   Default is "w2048"

       win_func
	   Set windowing function.

	   It accepts the following values:

	   rect
	   bartlett
	   hanning
	   hamming
	   blackman
	   welch
	   flattop
	   bharris
	   bnuttall
	   bhann
	   sine
	   nuttall
	   lanczos
	   gauss
	   tukey
	   dolph
	   cauchy
	   parzen
	   poisson

	   Default is "hanning".

       overlap
	   Set window overlap. In range "[0, 1]". Default is 1, which means
	   optimal overlap for selected window function will be picked.

       averaging
	   Set time averaging. Setting this to 0 will display current maximal
	   peaks.  Default is 1, which means time averaging is disabled.

       colors
	   Specify list of colors separated by space or by '|' which will be
	   used to draw channel frequencies. Unrecognized or missing colors
	   will be replaced by white color.

       cmode
	   Set channel display mode.

	   It accepts the following values:

	   combined
	   separate

	   Default is "combined".

       minamp
	   Set minimum amplitude used in "log" amplitude scaler.

   showspectrum
       Convert input audio to a video output, representing the audio frequency
       spectrum.

       The filter accepts the following options:

       size, s
	   Specify the video size for the output. For the syntax of this
	   option, check the "Video size" section in the ffmpeg-utils manual.
	   Default value is "640x512".

       slide
	   Specify how the spectrum should slide along the window.

	   It accepts the following values:

	   replace
	       the samples start again on the left when they reach the right

	   scroll
	       the samples scroll from right to left

	   fullframe
	       frames are only produced when the samples reach the right

	   rscroll
	       the samples scroll from left to right

	   Default value is "replace".

       mode
	   Specify display mode.

	   It accepts the following values:

	   combined
	       all channels are displayed in the same row

	   separate
	       all channels are displayed in separate rows

	   Default value is combined.

       color
	   Specify display color mode.

	   It accepts the following values:

	   channel
	       each channel is displayed in a separate color

	   intensity
	       each channel is displayed using the same color scheme

	   rainbow
	       each channel is displayed using the rainbow color scheme

	   moreland
	       each channel is displayed using the moreland color scheme

	   nebulae
	       each channel is displayed using the nebulae color scheme

	   fire
	       each channel is displayed using the fire color scheme

	   fiery
	       each channel is displayed using the fiery color scheme

	   fruit
	       each channel is displayed using the fruit color scheme

	   cool
	       each channel is displayed using the cool color scheme

	   Default value is channel.

       scale
	   Specify scale used for calculating intensity color values.

	   It accepts the following values:

	   lin linear

	   sqrt
	       square root, default

	   cbrt
	       cubic root

	   log logarithmic

	   4thrt
	       4th root

	   5thrt
	       5th root

	   Default value is sqrt.

       saturation
	   Set saturation modifier for displayed colors. Negative values
	   provide alternative color scheme. 0 is no saturation at all.
	   Saturation must be in [-10.0, 10.0] range.  Default value is 1.

       win_func
	   Set window function.

	   It accepts the following values:

	   rect
	   bartlett
	   hann
	   hanning
	   hamming
	   blackman
	   welch
	   flattop
	   bharris
	   bnuttall
	   bhann
	   sine
	   nuttall
	   lanczos
	   gauss
	   tukey
	   dolph
	   cauchy
	   parzen
	   poisson

	   Default value is "hann".

       orientation
	   Set orientation of time vs frequency axis. Can be "vertical" or
	   "horizontal". Default is "vertical".

       overlap
	   Set ratio of overlap window. Default value is 0.  When value is 1
	   overlap is set to recommended size for specific window function
	   currently used.

       gain
	   Set scale gain for calculating intensity color values.  Default
	   value is 1.

       data
	   Set which data to display. Can be "magnitude", default or "phase".

       rotation
	   Set color rotation, must be in [-1.0, 1.0] range.  Default value is
	   0.

       The usage is very similar to the showwaves filter; see the examples in
       that section.

       Examples

       ·   Large window with logarithmic color scaling:

		   showspectrum=s=1280x480:scale=log

       ·   Complete example for a colored and sliding spectrum per channel
	   using ffplay:

		   ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
				[a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'

   showspectrumpic
       Convert input audio to a single video frame, representing the audio
       frequency spectrum.

       The filter accepts the following options:

       size, s
	   Specify the video size for the output. For the syntax of this
	   option, check the "Video size" section in the ffmpeg-utils manual.
	   Default value is "4096x2048".

       mode
	   Specify display mode.

	   It accepts the following values:

	   combined
	       all channels are displayed in the same row

	   separate
	       all channels are displayed in separate rows

	   Default value is combined.

       color
	   Specify display color mode.

	   It accepts the following values:

	   channel
	       each channel is displayed in a separate color

	   intensity
	       each channel is displayed using the same color scheme

	   rainbow
	       each channel is displayed using the rainbow color scheme

	   moreland
	       each channel is displayed using the moreland color scheme

	   nebulae
	       each channel is displayed using the nebulae color scheme

	   fire
	       each channel is displayed using the fire color scheme

	   fiery
	       each channel is displayed using the fiery color scheme

	   fruit
	       each channel is displayed using the fruit color scheme

	   cool
	       each channel is displayed using the cool color scheme

	   Default value is intensity.

       scale
	   Specify scale used for calculating intensity color values.

	   It accepts the following values:

	   lin linear

	   sqrt
	       square root, default

	   cbrt
	       cubic root

	   log logarithmic

	   4thrt
	       4th root

	   5thrt
	       5th root

	   Default value is log.

       saturation
	   Set saturation modifier for displayed colors. Negative values
	   provide alternative color scheme. 0 is no saturation at all.
	   Saturation must be in [-10.0, 10.0] range.  Default value is 1.

       win_func
	   Set window function.

	   It accepts the following values:

	   rect
	   bartlett
	   hann
	   hanning
	   hamming
	   blackman
	   welch
	   flattop
	   bharris
	   bnuttall
	   bhann
	   sine
	   nuttall
	   lanczos
	   gauss
	   tukey
	   dolph
	   cauchy
	   parzen
	   poisson

	   Default value is "hann".

       orientation
	   Set orientation of time vs frequency axis. Can be "vertical" or
	   "horizontal". Default is "vertical".

       gain
	   Set scale gain for calculating intensity color values.  Default
	   value is 1.

       legend
	   Draw time and frequency axes and legends. Default is enabled.

       rotation
	   Set color rotation, must be in [-1.0, 1.0] range.  Default value is
	   0.

       Examples

       ·   Extract an audio spectrogram of a whole audio track in a 1024x1024
	   picture using ffmpeg:

		   ffmpeg -i audio.flac -lavfi showspectrumpic=s=1024x1024 spectrogram.png

   showvolume
       Convert input audio volume to a video output.

       The filter accepts the following options:

       rate, r
	   Set video rate.

       b   Set border width, allowed range is [0, 5]. Default is 1.

       w   Set channel width, allowed range is [80, 8192]. Default is 400.

       h   Set channel height, allowed range is [1, 900]. Default is 20.

       f   Set fade, allowed range is [0, 1]. Default is 0.95.

       c   Set volume color expression.

	   The expression can use the following variables:

	   VOLUME
	       Current max volume of channel in dB.

	   PEAK
	       Current peak.

	   CHANNEL
	       Current channel number, starting from 0.

       t   If set, displays channel names. Default is enabled.

       v   If set, displays volume values. Default is enabled.

       o   Set orientation, can be horizontal: "h" or vertical: "v", default
	   is "h".

       s   Set step size, allowed range is [0, 5]. Default is 0, which means
	   step is disabled.

       p   Set background opacity, allowed range is [0, 1]. Default is 0.

       m   Set metering mode, can be peak: "p" or rms: "r", default is "p".

       ds  Set display scale, can be linear: "lin" or log: "log", default is
	   "lin".

       dm  In second.  If set to > 0., display a line for the max level in the
	   previous seconds.  default is disabled: 0.

       dmc The color of the max line. Use when "dm" option is set to > 0.
	   default is: "orange"

   showwaves
       Convert input audio to a video output, representing the samples waves.

       The filter accepts the following options:

       size, s
	   Specify the video size for the output. For the syntax of this
	   option, check the "Video size" section in the ffmpeg-utils manual.
	   Default value is "600x240".

       mode
	   Set display mode.

	   Available values are:

	   point
	       Draw a point for each sample.

	   line
	       Draw a vertical line for each sample.

	   p2p Draw a point for each sample and a line between them.

	   cline
	       Draw a centered vertical line for each sample.

	   Default value is "point".

       n   Set the number of samples which are printed on the same column. A
	   larger value will decrease the frame rate. Must be a positive
	   integer. This option can be set only if the value for rate is not
	   explicitly specified.

       rate, r
	   Set the (approximate) output frame rate. This is done by setting
	   the option n. Default value is "25".

       split_channels
	   Set if channels should be drawn separately or overlap. Default
	   value is 0.

       colors
	   Set colors separated by '|' which are going to be used for drawing
	   of each channel.

       scale
	   Set amplitude scale.

	   Available values are:

	   lin Linear.

	   log Logarithmic.

	   sqrt
	       Square root.

	   cbrt
	       Cubic root.

	   Default is linear.

       draw
	   Set the draw mode. This is mostly useful to set for high n.

	   Available values are:

	   scale
	       Scale pixel values for each drawn sample.

	   full
	       Draw every sample directly.

	   Default value is "scale".

       Examples

       ·   Output the input file audio and the corresponding video
	   representation at the same time:

		   amovie=a.mp3,asplit[out0],showwaves[out1]

       ·   Create a synthetic signal and show it with showwaves, forcing a
	   frame rate of 30 frames per second:

		   aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]

   showwavespic
       Convert input audio to a single video frame, representing the samples
       waves.

       The filter accepts the following options:

       size, s
	   Specify the video size for the output. For the syntax of this
	   option, check the "Video size" section in the ffmpeg-utils manual.
	   Default value is "600x240".

       split_channels
	   Set if channels should be drawn separately or overlap. Default
	   value is 0.

       colors
	   Set colors separated by '|' which are going to be used for drawing
	   of each channel.

       scale
	   Set amplitude scale.

	   Available values are:

	   lin Linear.

	   log Logarithmic.

	   sqrt
	       Square root.

	   cbrt
	       Cubic root.

	   Default is linear.

       Examples

       ·   Extract a channel split representation of the wave form of a whole
	   audio track in a 1024x800 picture using ffmpeg:

		   ffmpeg -i audio.flac -lavfi showwavespic=split_channels=1:s=1024x800 waveform.png

   sidedata, asidedata
       Delete frame side data, or select frames based on it.

       This filter accepts the following options:

       mode
	   Set mode of operation of the filter.

	   Can be one of the following:

	   select
	       Select every frame with side data of "type".

	   delete
	       Delete side data of "type". If "type" is not set, delete all
	       side data in the frame.

       type
	   Set side data type used with all modes. Must be set for "select"
	   mode. For the list of frame side data types, refer to the
	   "AVFrameSideDataType" enum in libavutil/frame.h. For example, to
	   choose "AV_FRAME_DATA_PANSCAN" side data, you must specify
	   "PANSCAN".

   spectrumsynth
       Sythesize audio from 2 input video spectrums, first input stream
       represents magnitude across time and second represents phase across
       time.  The filter will transform from frequency domain as displayed in
       videos back to time domain as presented in audio output.

       This filter is primarily created for reversing processed showspectrum
       filter outputs, but can synthesize sound from other spectrograms too.
       But in such case results are going to be poor if the phase data is not
       available, because in such cases phase data need to be recreated,
       usually its just recreated from random noise.  For best results use
       gray only output ("channel" color mode in showspectrum filter) and
       "log" scale for magnitude video and "lin" scale for phase video. To
       produce phase, for 2nd video, use "data" option. Inputs videos should
       generally use "fullframe" slide mode as that saves resources needed for
       decoding video.

       The filter accepts the following options:

       sample_rate
	   Specify sample rate of output audio, the sample rate of audio from
	   which spectrum was generated may differ.

       channels
	   Set number of channels represented in input video spectrums.

       scale
	   Set scale which was used when generating magnitude input spectrum.
	   Can be "lin" or "log". Default is "log".

       slide
	   Set slide which was used when generating inputs spectrums.  Can be
	   "replace", "scroll", "fullframe" or "rscroll".  Default is
	   "fullframe".

       win_func
	   Set window function used for resynthesis.

       overlap
	   Set window overlap. In range "[0, 1]". Default is 1, which means
	   optimal overlap for selected window function will be picked.

       orientation
	   Set orientation of input videos. Can be "vertical" or "horizontal".
	   Default is "vertical".

       Examples

       ·   First create magnitude and phase videos from audio, assuming audio
	   is stereo with 44100 sample rate, then resynthesize videos back to
	   audio with spectrumsynth:

		   ffmpeg -i input.flac -lavfi showspectrum=mode=separate:scale=log:overlap=0.875:color=channel:slide=fullframe:data=magnitude -an -c:v rawvideo magnitude.nut
		   ffmpeg -i input.flac -lavfi showspectrum=mode=separate:scale=lin:overlap=0.875:color=channel:slide=fullframe:data=phase -an -c:v rawvideo phase.nut
		   ffmpeg -i magnitude.nut -i phase.nut -lavfi spectrumsynth=channels=2:sample_rate=44100:win_func=hann:overlap=0.875:slide=fullframe output.flac

   split, asplit
       Split input into several identical outputs.

       "asplit" works with audio input, "split" with video.

       The filter accepts a single parameter which specifies the number of
       outputs. If unspecified, it defaults to 2.

       Examples

       ·   Create two separate outputs from the same input:

		   [in] split [out0][out1]

       ·   To create 3 or more outputs, you need to specify the number of
	   outputs, like in:

		   [in] asplit=3 [out0][out1][out2]

       ·   Create two separate outputs from the same input, one cropped and
	   one padded:

		   [in] split [splitout1][splitout2];
		   [splitout1] crop=100:100:0:0    [cropout];
		   [splitout2] pad=200:200:100:100 [padout];

       ·   Create 5 copies of the input audio with ffmpeg:

		   ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT

   zmq, azmq
       Receive commands sent through a libzmq client, and forward them to
       filters in the filtergraph.

       "zmq" and "azmq" work as a pass-through filters. "zmq" must be inserted
       between two video filters, "azmq" between two audio filters. Both are
       capable to send messages to any filter type.

       To enable these filters you need to install the libzmq library and
       headers and configure FFmpeg with "--enable-libzmq".

       For more information about libzmq see: <http://www.zeromq.org/>

       The "zmq" and "azmq" filters work as a libzmq server, which receives
       messages sent through a network interface defined by the bind_address
       (or the abbreviation "b") option.  Default value of this option is
       tcp://localhost:5555. You may want to alter this value to your needs,
       but do not forget to escape any ':' signs (see filtergraph escaping).

       The received message must be in the form:

	       <TARGET> <COMMAND> [<ARG>]

       TARGET specifies the target of the command, usually the name of the
       filter class or a specific filter instance name. The default filter
       instance name uses the pattern Parsed_<filter_name>_<index>, but you
       can override this by using the filter_name@id syntax (see Filtergraph
       syntax).

       COMMAND specifies the name of the command for the target filter.

       ARG is optional and specifies the optional argument list for the given
       COMMAND.

       Upon reception, the message is processed and the corresponding command
       is injected into the filtergraph. Depending on the result, the filter
       will send a reply to the client, adopting the format:

	       <ERROR_CODE> <ERROR_REASON>
	       <MESSAGE>

       MESSAGE is optional.

       Examples

       Look at tools/zmqsend for an example of a zmq client which can be used
       to send commands processed by these filters.

       Consider the following filtergraph generated by ffplay.	In this
       example the last overlay filter has an instance name. All other filters
       will have default instance names.

	       ffplay -dumpgraph 1 -f lavfi "
	       color=s=100x100:c=red  [l];
	       color=s=100x100:c=blue [r];
	       nullsrc=s=200x100, zmq [bg];
	       [bg][l]	 overlay     [bg+l];
	       [bg+l][r] overlay@my=x=100 "

       To change the color of the left side of the video, the following
       command can be used:

	       echo Parsed_color_0 c yellow | tools/zmqsend

       To change the right side:

	       echo Parsed_color_1 c pink | tools/zmqsend

       To change the position of the right side:

	       echo overlay@my x 150 | tools/zmqsend

MULTIMEDIA SOURCES
       Below is a description of the currently available multimedia sources.

   amovie
       This is the same as movie source, except it selects an audio stream by
       default.

   movie
       Read audio and/or video stream(s) from a movie container.

       It accepts the following parameters:

       filename
	   The name of the resource to read (not necessarily a file; it can
	   also be a device or a stream accessed through some protocol).

       format_name, f
	   Specifies the format assumed for the movie to read, and can be
	   either the name of a container or an input device. If not
	   specified, the format is guessed from movie_name or by probing.

       seek_point, sp
	   Specifies the seek point in seconds. The frames will be output
	   starting from this seek point. The parameter is evaluated with
	   "av_strtod", so the numerical value may be suffixed by an IS
	   postfix. The default value is "0".

       streams, s
	   Specifies the streams to read. Several streams can be specified,
	   separated by "+". The source will then have as many outputs, in the
	   same order. The syntax is explained in the "Stream specifiers"
	   section in the ffmpeg manual. Two special names, "dv" and "da"
	   specify respectively the default (best suited) video and audio
	   stream. Default is "dv", or "da" if the filter is called as
	   "amovie".

       stream_index, si
	   Specifies the index of the video stream to read. If the value is
	   -1, the most suitable video stream will be automatically selected.
	   The default value is "-1". Deprecated. If the filter is called
	   "amovie", it will select audio instead of video.

       loop
	   Specifies how many times to read the stream in sequence.  If the
	   value is 0, the stream will be looped infinitely.  Default value is
	   "1".

	   Note that when the movie is looped the source timestamps are not
	   changed, so it will generate non monotonically increasing
	   timestamps.

       discontinuity
	   Specifies the time difference between frames above which the point
	   is considered a timestamp discontinuity which is removed by
	   adjusting the later timestamps.

       It allows overlaying a second video on top of the main input of a
       filtergraph, as shown in this graph:

	       input -----------> deltapts0 --> overlay --> output
						   ^
						   |
	       movie --> scale--> deltapts1 -------+

       Examples

       ·   Skip 3.2 seconds from the start of the AVI file in.avi, and overlay
	   it on top of the input labelled "in":

		   movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
		   [in] setpts=PTS-STARTPTS [main];
		   [main][over] overlay=16:16 [out]

       ·   Read from a video4linux2 device, and overlay it on top of the input
	   labelled "in":

		   movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
		   [in] setpts=PTS-STARTPTS [main];
		   [main][over] overlay=16:16 [out]

       ·   Read the first video stream and the audio stream with id 0x81 from
	   dvd.vob; the video is connected to the pad named "video" and the
	   audio is connected to the pad named "audio":

		   movie=dvd.vob:s=v:0+#0x81 [video] [audio]

       Commands

       Both movie and amovie support the following commands:

       seek
	   Perform seek using "av_seek_frame".	The syntax is: seek
	   stream_index|timestamp|flags

	   ·   stream_index: If stream_index is -1, a default stream is
	       selected, and timestamp is automatically converted from
	       AV_TIME_BASE units to the stream specific time_base.

	   ·   timestamp: Timestamp in AVStream.time_base units or, if no
	       stream is specified, in AV_TIME_BASE units.

	   ·   flags: Flags which select direction and seeking mode.

       get_duration
	   Get movie duration in AV_TIME_BASE units.

SEE ALSO
       ffmpeg(1), ffplay(1), ffprobe(1), libavfilter(3)

AUTHORS
       The FFmpeg developers.

       For details about the authorship, see the Git history of the project
       (git://source.ffmpeg.org/ffmpeg), e.g. by typing the command git log in
       the FFmpeg source directory, or browsing the online repository at
       <http://source.ffmpeg.org>.

       Maintainers for the specific components are listed in the file
       MAINTAINERS in the source code tree.

							     FFMPEG-FILTERS(1)
