1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 In libavfilter, it is possible for filters to have multiple inputs and
8 To illustrate the sorts of things that are possible, we can
9 use a complex filter graph. For example, the following one:
12 input --> split ---------------------> overlay --> output
15 +-----> crop --> vflip -------+
18 splits the stream in two streams, sends one stream through the crop filter
19 and the vflip filter before merging it back with the other stream by
20 overlaying it on top. You can use the following command to achieve this:
23 ffmpeg -i input -vf "[in] split [T1], [T2] overlay=0:H/2 [out]; [T1] crop=iw:ih/2:0:ih/2, vflip [T2]" output
26 The result will be that in output the top half of the video is mirrored
29 Filters are loaded using the @var{-vf} or @var{-af} option passed to
30 @command{ffmpeg} or to @command{ffplay}. Filters in the same linear
31 chain are separated by commas. In our example, @var{split,
32 overlay} are in one linear chain, and @var{crop, vflip} are in
33 another. The points where the linear chains join are labeled by names
34 enclosed in square brackets. In our example, that is @var{[T1]} and
35 @var{[T2]}. The special labels @var{[in]} and @var{[out]} are the points
36 where video is input and output.
38 Some filters take in input a list of parameters: they are specified
39 after the filter name and an equal sign, and are separated from each other
42 There exist so-called @var{source filters} that do not have an
43 audio/video input, and @var{sink filters} that will not have audio/video
46 @c man end FILTERING INTRODUCTION
49 @c man begin GRAPH2DOT
51 The @file{graph2dot} program included in the FFmpeg @file{tools}
52 directory can be used to parse a filter graph description and issue a
53 corresponding textual representation in the dot language.
60 to see how to use @file{graph2dot}.
62 You can then pass the dot description to the @file{dot} program (from
63 the graphviz suite of programs) and obtain a graphical representation
66 For example the sequence of commands:
68 echo @var{GRAPH_DESCRIPTION} | \
69 tools/graph2dot -o graph.tmp && \
70 dot -Tpng graph.tmp -o graph.png && \
74 can be used to create and display an image representing the graph
75 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
76 a complete self-contained graph, with its inputs and outputs explicitly defined.
77 For example if your command line is of the form:
79 ffmpeg -i infile -vf scale=640:360 outfile
81 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
83 nullsrc,scale=640:360,nullsink
85 you may also need to set the @var{nullsrc} parameters and add a @var{format}
86 filter in order to simulate a specific input file.
90 @chapter Filtergraph description
91 @c man begin FILTERGRAPH DESCRIPTION
93 A filtergraph is a directed graph of connected filters. It can contain
94 cycles, and there can be multiple links between a pair of
95 filters. Each link has one input pad on one side connecting it to one
96 filter from which it takes its input, and one output pad on the other
97 side connecting it to the one filter accepting its output.
99 Each filter in a filtergraph is an instance of a filter class
100 registered in the application, which defines the features and the
101 number of input and output pads of the filter.
103 A filter with no input pads is called a "source", a filter with no
104 output pads is called a "sink".
106 @anchor{Filtergraph syntax}
107 @section Filtergraph syntax
109 A filtergraph can be represented using a textual representation, which is
110 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
111 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
112 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
113 @file{libavfilter/avfiltergraph.h}.
115 A filterchain consists of a sequence of connected filters, each one
116 connected to the previous one in the sequence. A filterchain is
117 represented by a list of ","-separated filter descriptions.
119 A filtergraph consists of a sequence of filterchains. A sequence of
120 filterchains is represented by a list of ";"-separated filterchain
123 A filter is represented by a string of the form:
124 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
126 @var{filter_name} is the name of the filter class of which the
127 described filter is an instance of, and has to be the name of one of
128 the filter classes registered in the program.
129 The name of the filter class is optionally followed by a string
132 @var{arguments} is a string which contains the parameters used to
133 initialize the filter instance, and are described in the filter
136 The list of arguments can be quoted using the character "'" as initial
137 and ending mark, and the character '\' for escaping the characters
138 within the quoted text; otherwise the argument string is considered
139 terminated when the next special character (belonging to the set
140 "[]=;,") is encountered.
142 The name and arguments of the filter are optionally preceded and
143 followed by a list of link labels.
144 A link label allows to name a link and associate it to a filter output
145 or input pad. The preceding labels @var{in_link_1}
146 ... @var{in_link_N}, are associated to the filter input pads,
147 the following labels @var{out_link_1} ... @var{out_link_M}, are
148 associated to the output pads.
150 When two link labels with the same name are found in the
151 filtergraph, a link between the corresponding input and output pad is
154 If an output pad is not labelled, it is linked by default to the first
155 unlabelled input pad of the next filter in the filterchain.
156 For example in the filterchain:
158 nullsrc, split[L1], [L2]overlay, nullsink
160 the split filter instance has two output pads, and the overlay filter
161 instance two input pads. The first output pad of split is labelled
162 "L1", the first input pad of overlay is labelled "L2", and the second
163 output pad of split is linked to the second input pad of overlay,
164 which are both unlabelled.
166 In a complete filterchain all the unlabelled filter input and output
167 pads must be connected. A filtergraph is considered valid if all the
168 filter input and output pads of all the filterchains are connected.
170 Libavfilter will automatically insert scale filters where format
171 conversion is required. It is possible to specify swscale flags
172 for those automatically inserted scalers by prepending
173 @code{sws_flags=@var{flags};}
174 to the filtergraph description.
176 Follows a BNF description for the filtergraph syntax:
178 @var{NAME} ::= sequence of alphanumeric characters and '_'
179 @var{LINKLABEL} ::= "[" @var{NAME} "]"
180 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
181 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
182 @var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
183 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
184 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
187 @section Notes on filtergraph escaping
189 Some filter arguments require the use of special characters, typically
190 @code{:} to separate key=value pairs in a named options list. In this
191 case the user should perform a first level escaping when specifying
192 the filter arguments. For example, consider the following literal
193 string to be embedded in the @ref{drawtext} filter arguments:
195 this is a 'string': may contain one, or more, special characters
198 Since @code{:} is special for the filter arguments syntax, it needs to
199 be escaped, so you get:
201 text=this is a \'string\'\: may contain one, or more, special characters
204 A second level of escaping is required when embedding the filter
205 arguments in a filtergraph description, in order to escape all the
206 filtergraph special characters. Thus the example above becomes:
208 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
211 Finally an additional level of escaping may be needed when writing the
212 filtergraph description in a shell command, which depends on the
213 escaping rules of the adopted shell. For example, assuming that
214 @code{\} is special and needs to be escaped with another @code{\}, the
215 previous string will finally result in:
217 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
220 Sometimes, it might be more convenient to employ quoting in place of
221 escaping. For example the string:
223 Caesar: tu quoque, Brute, fili mi
226 Can be quoted in the filter arguments as:
228 text='Caesar: tu quoque, Brute, fili mi'
231 And finally inserted in a filtergraph like:
233 drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
236 See the ``Quoting and escaping'' section in the ffmpeg-utils manual
237 for more information about the escaping and quoting rules adopted by
240 @c man end FILTERGRAPH DESCRIPTION
242 @chapter Audio Filters
243 @c man begin AUDIO FILTERS
245 When you configure your FFmpeg build, you can disable any of the
246 existing filters using @code{--disable-filters}.
247 The configure output will show the audio filters included in your
250 Below is a description of the currently available audio filters.
254 Convert the input audio format to the specified formats.
256 The filter accepts a string of the form:
257 "@var{sample_format}:@var{channel_layout}".
259 @var{sample_format} specifies the sample format, and can be a string or the
260 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
261 suffix for a planar sample format.
263 @var{channel_layout} specifies the channel layout, and can be a string
264 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
266 The special parameter "auto", signifies that the filter will
267 automatically select the output format depending on the output filter.
269 Some examples follow.
273 Convert input to float, planar, stereo:
279 Convert input to unsigned 8-bit, automatically select out channel layout:
287 Apply a two-pole all-pass filter with central frequency (in Hz)
288 @var{frequency}, and filter-width @var{width}.
289 An all-pass filter changes the audio's frequency to phase relationship
290 without changing its frequency to amplitude relationship.
292 The filter accepts parameters as a list of @var{key}=@var{value}
293 pairs, separated by ":".
295 A description of the accepted parameters follows.
302 Set method to specify band-width of filter.
315 Specify the band-width of a filter in width_type units.
320 Apply a high-pass filter with 3dB point frequency.
321 The filter can be either single-pole, or double-pole (the default).
322 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
324 The filter accepts parameters as a list of @var{key}=@var{value}
325 pairs, separated by ":".
327 A description of the accepted parameters follows.
331 Set frequency in Hz. Default is 3000.
334 Set number of poles. Default is 2.
337 Set method to specify band-width of filter.
350 Specify the band-width of a filter in width_type units.
351 Applies only to double-pole filter.
352 The default is 0.707q and gives a Butterworth response.
357 Apply a low-pass filter with 3dB point frequency.
358 The filter can be either single-pole or double-pole (the default).
359 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
361 The filter accepts parameters as a list of @var{key}=@var{value}
362 pairs, separated by ":".
364 A description of the accepted parameters follows.
368 Set frequency in Hz. Default is 500.
371 Set number of poles. Default is 2.
374 Set method to specify band-width of filter.
387 Specify the band-width of a filter in width_type units.
388 Applies only to double-pole filter.
389 The default is 0.707q and gives a Butterworth response.
394 Boost or cut the bass (lower) frequencies of the audio using a two-pole
395 shelving filter with a response similar to that of a standard
396 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
398 The filter accepts parameters as a list of @var{key}=@var{value}
399 pairs, separated by ":".
401 A description of the accepted parameters follows.
405 Give the gain at 0 Hz. Its useful range is about -20
406 (for a large cut) to +20 (for a large boost).
407 Beware of clipping when using a positive gain.
410 Set the filter's central frequency and so can be used
411 to extend or reduce the frequency range to be boosted or cut.
412 The default value is @code{100} Hz.
415 Set method to specify band-width of filter.
428 Determine how steep is the filter's shelf transition.
433 Boost or cut treble (upper) frequencies of the audio using a two-pole
434 shelving filter with a response similar to that of a standard
435 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
437 The filter accepts parameters as a list of @var{key}=@var{value}
438 pairs, separated by ":".
440 A description of the accepted parameters follows.
444 Give the gain at whichever is the lower of ~22 kHz and the
445 Nyquist frequency. Its useful range is about -20 (for a large cut)
446 to +20 (for a large boost). Beware of clipping when using a positive gain.
449 Set the filter's central frequency and so can be used
450 to extend or reduce the frequency range to be boosted or cut.
451 The default value is @code{3000} Hz.
454 Set method to specify band-width of filter.
467 Determine how steep is the filter's shelf transition.
472 Apply a two-pole Butterworth band-pass filter with central
473 frequency @var{frequency}, and (3dB-point) band-width width.
474 The @var{csg} option selects a constant skirt gain (peak gain = Q)
475 instead of the default: constant 0dB peak gain.
476 The filter roll off at 6dB per octave (20dB per decade).
478 The filter accepts parameters as a list of @var{key}=@var{value}
479 pairs, separated by ":".
481 A description of the accepted parameters follows.
485 Set the filter's central frequency. Default is @code{3000}.
488 Constant skirt gain if set to 1. Defaults to 0.
491 Set method to specify band-width of filter.
504 Specify the band-width of a filter in width_type units.
509 Apply a two-pole Butterworth band-reject filter with central
510 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
511 The filter roll off at 6dB per octave (20dB per decade).
513 The filter accepts parameters as a list of @var{key}=@var{value}
514 pairs, separated by ":".
516 A description of the accepted parameters follows.
520 Set the filter's central frequency. Default is @code{3000}.
523 Set method to specify band-width of filter.
536 Specify the band-width of a filter in width_type units.
541 Apply a biquad IIR filter with the given coefficients.
542 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
543 are the numerator and denominator coefficients respectively.
547 Apply a two-pole peaking equalisation (EQ) filter. With this
548 filter, the signal-level at and around a selected frequency can
549 be increased or decreased, whilst (unlike bandpass and bandreject
550 filters) that at all other frequencies is unchanged.
552 In order to produce complex equalisation curves, this filter can
553 be given several times, each with a different central frequency.
555 The filter accepts parameters as a list of @var{key}=@var{value}
556 pairs, separated by ":".
558 A description of the accepted parameters follows.
562 Set the filter's central frequency in Hz.
565 Set method to specify band-width of filter.
578 Specify the band-width of a filter in width_type units.
581 Set the required gain or attenuation in dB.
582 Beware of clipping when using a positive gain.
587 Apply fade-in/out effect to input audio.
589 The filter accepts parameters as a list of @var{key}=@var{value}
590 pairs, separated by ":".
592 A description of the accepted parameters follows.
596 Specify the effect type, can be either @code{in} for fade-in, or
597 @code{out} for a fade-out effect. Default is @code{in}.
599 @item start_sample, ss
600 Specify the number of the start sample for starting to apply the fade
601 effect. Default is 0.
604 Specify the number of samples for which the fade effect has to last. At
605 the end of the fade-in effect the output audio will have the same
606 volume as the input audio, at the end of the fade-out transition
607 the output audio will be silence. Default is 44100.
610 Specify time in seconds for starting to apply the fade
611 effect. Default is 0.
612 If set this option is used instead of @var{start_sample} one.
615 Specify the number of seconds for which the fade effect has to last. At
616 the end of the fade-in effect the output audio will have the same
617 volume as the input audio, at the end of the fade-out transition
618 the output audio will be silence. Default is 0.
619 If set this option is used instead of @var{nb_samples} one.
622 Set curve for fade transition.
624 It accepts the following values:
627 select triangular, linear slope (default)
629 select quarter of sine wave
631 select half of sine wave
633 select exponential sine wave
637 select inverted parabola
652 Fade in first 15 seconds of audio:
658 Fade out last 25 seconds of a 900 seconds audio:
660 afade=t=out:ss=875:d=25
666 Set output format constraints for the input audio. The framework will
667 negotiate the most appropriate format to minimize conversions.
669 The filter accepts the following named parameters:
673 A comma-separated list of requested sample formats.
676 A comma-separated list of requested sample rates.
678 @item channel_layouts
679 A comma-separated list of requested channel layouts.
683 If a parameter is omitted, all values are allowed.
685 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
687 aformat='sample_fmts=u8,s16:channel_layouts=stereo'
692 Merge two or more audio streams into a single multi-channel stream.
694 The filter accepts the following named options:
699 Set the number of inputs. Default is 2.
703 If the channel layouts of the inputs are disjoint, and therefore compatible,
704 the channel layout of the output will be set accordingly and the channels
705 will be reordered as necessary. If the channel layouts of the inputs are not
706 disjoint, the output will have all the channels of the first input then all
707 the channels of the second input, in that order, and the channel layout of
708 the output will be the default value corresponding to the total number of
711 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
712 is FC+BL+BR, then the output will be in 5.1, with the channels in the
713 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
714 first input, b1 is the first channel of the second input).
716 On the other hand, if both input are in stereo, the output channels will be
717 in the default order: a1, a2, b1, b2, and the channel layout will be
718 arbitrarily set to 4.0, which may or may not be the expected value.
720 All inputs must have the same sample rate, and format.
722 If inputs do not have the same duration, the output will stop with the
725 Example: merge two mono files into a stereo stream:
727 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
730 Example: multiple merges:
733 amovie=input.mkv:si=0 [a0];
734 amovie=input.mkv:si=1 [a1];
735 amovie=input.mkv:si=2 [a2];
736 amovie=input.mkv:si=3 [a3];
737 amovie=input.mkv:si=4 [a4];
738 amovie=input.mkv:si=5 [a5];
739 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
744 Mixes multiple audio inputs into a single output.
748 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
750 will mix 3 input audio streams to a single output with the same duration as the
751 first input and a dropout transition time of 3 seconds.
753 The filter accepts the following named parameters:
757 Number of inputs. If unspecified, it defaults to 2.
760 How to determine the end-of-stream.
764 Duration of longest input. (default)
767 Duration of shortest input.
770 Duration of first input.
774 @item dropout_transition
775 Transition time, in seconds, for volume renormalization when an input
776 stream ends. The default value is 2 seconds.
782 Pass the audio source unchanged to the output.
786 Pad the end of a audio stream with silence, this can be used together with
787 -shortest to extend audio streams to the same length as the video stream.
792 Resample the input audio to the specified parameters, using the
793 libswresample library. If none are specified then the filter will
794 automatically convert between its input and output.
796 This filter is also able to stretch/squeeze the audio data to make it match
797 the timestamps or to inject silence / cut out audio to make it match the
798 timestamps, do a combination of both or do neither.
800 The filter accepts the syntax
801 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
802 expresses a sample rate and @var{resampler_options} is a list of
803 @var{key}=@var{value} pairs, separated by ":". See the
804 ffmpeg-resampler manual for the complete list of supported options.
806 For example, to resample the input audio to 44100Hz:
811 To stretch/squeeze samples to the given timestamps, with a maximum of 1000
812 samples per second compensation:
817 @section asetnsamples
819 Set the number of samples per each output audio frame.
821 The last output packet may contain a different number of samples, as
822 the filter will flush all the remaining samples when the input audio
825 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
830 @item nb_out_samples, n
831 Set the number of frames per each output audio frame. The number is
832 intended as the number of samples @emph{per each channel}.
833 Default value is 1024.
836 If set to 1, the filter will pad the last audio frame with zeroes, so
837 that the last frame will contain the same number of samples as the
838 previous ones. Default value is 1.
841 For example, to set the number of per-frame samples to 1234 and
842 disable padding for the last frame, use:
844 asetnsamples=n=1234:p=0
849 Show a line containing various information for each input audio frame.
850 The input audio is not modified.
852 The shown line contains a sequence of key/value pairs of the form
853 @var{key}:@var{value}.
855 A description of each shown parameter follows:
859 sequential number of the input frame, starting from 0
862 Presentation timestamp of the input frame, in time base units; the time base
863 depends on the filter input pad, and is usually 1/@var{sample_rate}.
866 presentation timestamp of the input frame in seconds
869 position of the frame in the input stream, -1 if this information in
870 unavailable and/or meaningless (for example in case of synthetic audio)
879 sample rate for the audio frame
882 number of samples (per channel) in the frame
885 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
886 the data is treated as if all the planes were concatenated.
888 @item plane_checksums
889 A list of Adler-32 checksums for each data plane.
894 Split input audio into several identical outputs.
896 The filter accepts a single parameter which specifies the number of outputs. If
897 unspecified, it defaults to 2.
901 [in] asplit [out0][out1]
904 will create two separate outputs from the same input.
906 To create 3 or more outputs, you need to specify the number of
909 [in] asplit=3 [out0][out1][out2]
913 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
915 will create 5 copies of the input audio.
920 Forward two audio streams and control the order the buffers are forwarded.
922 The argument to the filter is an expression deciding which stream should be
923 forwarded next: if the result is negative, the first stream is forwarded; if
924 the result is positive or zero, the second stream is forwarded. It can use
925 the following variables:
929 number of buffers forwarded so far on each stream
931 number of samples forwarded so far on each stream
933 current timestamp of each stream
936 The default value is @code{t1-t2}, which means to always forward the stream
937 that has a smaller timestamp.
939 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
940 input, while avoiding too much of a desynchronization:
942 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
943 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
951 The filter accepts exactly one parameter, the audio tempo. If not
952 specified then the filter will assume nominal 1.0 tempo. Tempo must
953 be in the [0.5, 2.0] range.
955 For example, to slow down audio to 80% tempo:
960 For example, to speed up audio to 125% tempo:
967 Make audio easier to listen to on headphones.
969 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
970 so that when listened to on headphones the stereo image is moved from
971 inside your head (standard for headphones) to outside and in front of
972 the listener (standard for speakers).
978 Mix channels with specific gain levels. The filter accepts the output
979 channel layout followed by a set of channels definitions.
981 This filter is also designed to remap efficiently the channels of an audio
984 The filter accepts parameters of the form:
985 "@var{l}:@var{outdef}:@var{outdef}:..."
989 output channel layout or number of channels
992 output channel specification, of the form:
993 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
996 output channel to define, either a channel name (FL, FR, etc.) or a channel
997 number (c0, c1, etc.)
1000 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1003 input channel to use, see out_name for details; it is not possible to mix
1004 named and numbered input channels
1007 If the `=' in a channel specification is replaced by `<', then the gains for
1008 that specification will be renormalized so that the total is 1, thus
1009 avoiding clipping noise.
1011 @subsection Mixing examples
1013 For example, if you want to down-mix from stereo to mono, but with a bigger
1014 factor for the left channel:
1016 pan=1:c0=0.9*c0+0.1*c1
1019 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1020 7-channels surround:
1022 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1025 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1026 that should be preferred (see "-ac" option) unless you have very specific
1029 @subsection Remapping examples
1031 The channel remapping will be effective if, and only if:
1034 @item gain coefficients are zeroes or ones,
1035 @item only one input per channel output,
1038 If all these conditions are satisfied, the filter will notify the user ("Pure
1039 channel mapping detected"), and use an optimized and lossless method to do the
1042 For example, if you have a 5.1 source and want a stereo audio stream by
1043 dropping the extra channels:
1045 pan="stereo: c0=FL : c1=FR"
1048 Given the same source, you can also switch front left and front right channels
1049 and keep the input channel layout:
1051 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1054 If the input is a stereo audio stream, you can mute the front left channel (and
1055 still keep the stereo channel layout) with:
1060 Still with a stereo audio stream input, you can copy the right channel in both
1061 front left and right:
1063 pan="stereo: c0=FR : c1=FR"
1066 @section silencedetect
1068 Detect silence in an audio stream.
1070 This filter logs a message when it detects that the input audio volume is less
1071 or equal to a noise tolerance value for a duration greater or equal to the
1072 minimum detected noise duration.
1074 The printed times and duration are expressed in seconds.
1078 Set silence duration until notification (default is 2 seconds).
1081 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1082 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1085 Detect 5 seconds of silence with -50dB noise tolerance:
1087 silencedetect=n=-50dB:d=5
1090 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1091 tolerance in @file{silence.mp3}:
1093 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
1097 Synchronize audio data with timestamps by squeezing/stretching it and/or
1098 dropping samples/adding silence when needed.
1100 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1102 The filter accepts the following named parameters:
1106 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1107 by default. When disabled, time gaps are covered with silence.
1110 Minimum difference between timestamps and audio data (in seconds) to trigger
1111 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1112 this filter, try setting this parameter to 0.
1115 Maximum compensation in samples per second. Relevant only with compensate=1.
1119 Assume the first pts should be this value. The time base is 1 / sample rate.
1120 This allows for padding/trimming at the start of stream. By default, no
1121 assumption is made about the first frame's expected pts, so no padding or
1122 trimming is done. For example, this could be set to 0 to pad the beginning with
1123 silence if an audio stream starts after the video stream or to trim any samples
1124 with a negative pts due to encoder delay.
1128 @section channelsplit
1129 Split each channel in input audio stream into a separate output stream.
1131 This filter accepts the following named parameters:
1133 @item channel_layout
1134 Channel layout of the input stream. Default is "stereo".
1137 For example, assuming a stereo input MP3 file
1139 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1141 will create an output Matroska file with two audio streams, one containing only
1142 the left channel and the other the right channel.
1144 To split a 5.1 WAV file into per-channel files
1146 ffmpeg -i in.wav -filter_complex
1147 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1148 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1149 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1154 Remap input channels to new locations.
1156 This filter accepts the following named parameters:
1158 @item channel_layout
1159 Channel layout of the output stream.
1162 Map channels from input to output. The argument is a comma-separated list of
1163 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1164 @var{in_channel} form. @var{in_channel} can be either the name of the input
1165 channel (e.g. FL for front left) or its index in the input channel layout.
1166 @var{out_channel} is the name of the output channel or its index in the output
1167 channel layout. If @var{out_channel} is not given then it is implicitly an
1168 index, starting with zero and increasing by one for each mapping.
1171 If no mapping is present, the filter will implicitly map input channels to
1172 output channels preserving index.
1174 For example, assuming a 5.1+downmix input MOV file
1176 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
1178 will create an output WAV file tagged as stereo from the downmix channels of
1181 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1183 ffmpeg -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
1187 Join multiple input streams into one multi-channel stream.
1189 The filter accepts the following named parameters:
1193 Number of input streams. Defaults to 2.
1195 @item channel_layout
1196 Desired output channel layout. Defaults to stereo.
1199 Map channels from inputs to output. The argument is a comma-separated list of
1200 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1201 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1202 can be either the name of the input channel (e.g. FL for front left) or its
1203 index in the specified input stream. @var{out_channel} is the name of the output
1207 The filter will attempt to guess the mappings when those are not specified
1208 explicitly. It does so by first trying to find an unused matching input channel
1209 and if that fails it picks the first unused input channel.
1211 E.g. to join 3 inputs (with properly set channel layouts)
1213 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1216 To build a 5.1 output from 6 single-channel streams:
1218 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1219 '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'
1224 Convert the audio sample format, sample rate and channel layout. This filter is
1225 not meant to be used directly.
1229 Adjust the input audio volume.
1231 The filter accepts the following named parameters. If the key of the
1232 first options is omitted, the arguments are interpreted according to
1233 the following syntax:
1235 volume=@var{volume}:@var{precision}
1241 Expresses how the audio volume will be increased or decreased.
1243 Output values are clipped to the maximum value.
1245 The output audio volume is given by the relation:
1247 @var{output_volume} = @var{volume} * @var{input_volume}
1250 Default value for @var{volume} is 1.0.
1253 Set the mathematical precision.
1255 This determines which input sample formats will be allowed, which affects the
1256 precision of the volume scaling.
1260 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1262 32-bit floating-point; limits input sample format to FLT. (default)
1264 64-bit floating-point; limits input sample format to DBL.
1268 @subsection Examples
1272 Halve the input audio volume:
1276 volume=volume=-6.0206dB
1279 In all the above example the named key for @option{volume} can be
1280 omitted, for example like in:
1286 Increase input audio power by 6 decibels using fixed-point precision:
1288 volume=volume=6dB:precision=fixed
1292 @section volumedetect
1294 Detect the volume of the input video.
1296 The filter has no parameters. The input is not modified. Statistics about
1297 the volume will be printed in the log when the input stream end is reached.
1299 In particular it will show the mean volume (root mean square), maximum
1300 volume (on a per-sample basis), and the beginning of an histogram of the
1301 registered volume values (from the maximum value to a cumulated 1/1000 of
1304 All volumes are in decibels relative to the maximum PCM value.
1306 Here is an excerpt of the output:
1308 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1309 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1310 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1311 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1312 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1313 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1314 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1315 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1316 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1322 The mean square energy is approximately -27 dB, or 10^-2.7.
1324 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1326 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1329 In other words, raising the volume by +4 dB does not cause any clipping,
1330 raising it by +5 dB causes clipping for 6 samples, etc.
1332 @c man end AUDIO FILTERS
1334 @chapter Audio Sources
1335 @c man begin AUDIO SOURCES
1337 Below is a description of the currently available audio sources.
1341 Buffer audio frames, and make them available to the filter chain.
1343 This source is mainly intended for a programmatic use, in particular
1344 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1346 It accepts the following mandatory parameters:
1347 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
1352 The sample rate of the incoming audio buffers.
1355 The sample format of the incoming audio buffers.
1356 Either a sample format name or its corresponging integer representation from
1357 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1359 @item channel_layout
1360 The channel layout of the incoming audio buffers.
1361 Either a channel layout name from channel_layout_map in
1362 @file{libavutil/channel_layout.c} or its corresponding integer representation
1363 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1366 The number of channels of the incoming audio buffers.
1367 If both @var{channels} and @var{channel_layout} are specified, then they
1374 abuffer=44100:s16p:stereo
1377 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1378 Since the sample format with name "s16p" corresponds to the number
1379 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1387 Generate an audio signal specified by an expression.
1389 This source accepts in input one or more expressions (one for each
1390 channel), which are evaluated and used to generate a corresponding
1393 It accepts the syntax: @var{exprs}[::@var{options}].
1394 @var{exprs} is a list of expressions separated by ":", one for each
1395 separate channel. In case the @var{channel_layout} is not
1396 specified, the selected channel layout depends on the number of
1397 provided expressions.
1399 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1402 The description of the accepted options follows.
1406 @item channel_layout, c
1407 Set the channel layout. The number of channels in the specified layout
1408 must be equal to the number of specified expressions.
1411 Set the minimum duration of the sourced audio. See the function
1412 @code{av_parse_time()} for the accepted format.
1413 Note that the resulting duration may be greater than the specified
1414 duration, as the generated audio is always cut at the end of a
1417 If not specified, or the expressed duration is negative, the audio is
1418 supposed to be generated forever.
1421 Set the number of samples per channel per each output frame,
1424 @item sample_rate, s
1425 Specify the sample rate, default to 44100.
1428 Each expression in @var{exprs} can contain the following constants:
1432 number of the evaluated sample, starting from 0
1435 time of the evaluated sample expressed in seconds, starting from 0
1442 @subsection Examples
1454 Generate a sin signal with frequency of 440 Hz, set sample rate to
1457 aevalsrc="sin(440*2*PI*t)::s=8000"
1461 Generate a two channels signal, specify the channel layout (Front
1462 Center + Back Center) explicitly:
1464 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1468 Generate white noise:
1470 aevalsrc="-2+random(0)"
1474 Generate an amplitude modulated signal:
1476 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1480 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1482 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1489 Null audio source, return unprocessed audio frames. It is mainly useful
1490 as a template and to be employed in analysis / debugging tools, or as
1491 the source for filters which ignore the input data (for example the sox
1494 It accepts an optional sequence of @var{key}=@var{value} pairs,
1497 The description of the accepted options follows.
1501 @item sample_rate, s
1502 Specify the sample rate, and defaults to 44100.
1504 @item channel_layout, cl
1506 Specify the channel layout, and can be either an integer or a string
1507 representing a channel layout. The default value of @var{channel_layout}
1510 Check the channel_layout_map definition in
1511 @file{libavutil/channel_layout.c} for the mapping between strings and
1512 channel layout values.
1515 Set the number of samples per requested frames.
1519 Follow some examples:
1521 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1522 anullsrc=r=48000:cl=4
1525 anullsrc=r=48000:cl=mono
1529 Buffer audio frames, and make them available to the filter chain.
1531 This source is not intended to be part of user-supplied graph descriptions but
1532 for insertion by calling programs through the interface defined in
1533 @file{libavfilter/buffersrc.h}.
1535 It accepts the following named parameters:
1539 Timebase which will be used for timestamps of submitted frames. It must be
1540 either a floating-point number or in @var{numerator}/@var{denominator} form.
1546 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1548 @item channel_layout
1549 Channel layout of the audio data, in the form that can be accepted by
1550 @code{av_get_channel_layout()}.
1553 All the parameters need to be explicitly defined.
1557 Synthesize a voice utterance using the libflite library.
1559 To enable compilation of this filter you need to configure FFmpeg with
1560 @code{--enable-libflite}.
1562 Note that the flite library is not thread-safe.
1564 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1567 The description of the accepted parameters follows.
1572 If set to 1, list the names of the available voices and exit
1573 immediately. Default value is 0.
1576 Set the maximum number of samples per frame. Default value is 512.
1579 Set the filename containing the text to speak.
1582 Set the text to speak.
1585 Set the voice to use for the speech synthesis. Default value is
1586 @code{kal}. See also the @var{list_voices} option.
1589 @subsection Examples
1593 Read from file @file{speech.txt}, and synthetize the text using the
1594 standard flite voice:
1596 flite=textfile=speech.txt
1600 Read the specified text selecting the @code{slt} voice:
1602 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1606 Input text to ffmpeg:
1608 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1612 Make @file{ffplay} speak the specified text, using @code{flite} and
1613 the @code{lavfi} device:
1615 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1619 For more information about libflite, check:
1620 @url{http://www.speech.cs.cmu.edu/flite/}
1622 @c man end AUDIO SOURCES
1624 @chapter Audio Sinks
1625 @c man begin AUDIO SINKS
1627 Below is a description of the currently available audio sinks.
1629 @section abuffersink
1631 Buffer audio frames, and make them available to the end of filter chain.
1633 This sink is mainly intended for programmatic use, in particular
1634 through the interface defined in @file{libavfilter/buffersink.h}.
1636 It requires a pointer to an AVABufferSinkContext structure, which
1637 defines the incoming buffers' formats, to be passed as the opaque
1638 parameter to @code{avfilter_init_filter} for initialization.
1642 Null audio sink, do absolutely nothing with the input audio. It is
1643 mainly useful as a template and to be employed in analysis / debugging
1646 @section abuffersink
1647 This sink is intended for programmatic use. Frames that arrive on this sink can
1648 be retrieved by the calling program using the interface defined in
1649 @file{libavfilter/buffersink.h}.
1651 This filter accepts no parameters.
1653 @c man end AUDIO SINKS
1655 @chapter Video Filters
1656 @c man begin VIDEO FILTERS
1658 When you configure your FFmpeg build, you can disable any of the
1659 existing filters using @code{--disable-filters}.
1660 The configure output will show the video filters included in your
1663 Below is a description of the currently available video filters.
1665 @section alphaextract
1667 Extract the alpha component from the input as a grayscale video. This
1668 is especially useful with the @var{alphamerge} filter.
1672 Add or replace the alpha component of the primary input with the
1673 grayscale value of a second input. This is intended for use with
1674 @var{alphaextract} to allow the transmission or storage of frame
1675 sequences that have alpha in a format that doesn't support an alpha
1678 For example, to reconstruct full frames from a normal YUV-encoded video
1679 and a separate video created with @var{alphaextract}, you might use:
1681 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1684 Since this filter is designed for reconstruction, it operates on frame
1685 sequences without considering timestamps, and terminates when either
1686 input reaches end of stream. This will cause problems if your encoding
1687 pipeline drops frames. If you're trying to apply an image as an
1688 overlay to a video stream, consider the @var{overlay} filter instead.
1692 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1693 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1694 Substation Alpha) subtitles files.
1698 Compute the bounding box for the non-black pixels in the input frame
1701 This filter computes the bounding box containing all the pixels with a
1702 luminance value greater than the minimum allowed value.
1703 The parameters describing the bounding box are printed on the filter
1706 @section blackdetect
1708 Detect video intervals that are (almost) completely black. Can be
1709 useful to detect chapter transitions, commercials, or invalid
1710 recordings. Output lines contains the time for the start, end and
1711 duration of the detected black interval expressed in seconds.
1713 In order to display the output lines, you need to set the loglevel at
1714 least to the AV_LOG_INFO value.
1716 This filter accepts a list of options in the form of
1717 @var{key}=@var{value} pairs separated by ":". A description of the
1718 accepted options follows.
1721 @item black_min_duration, d
1722 Set the minimum detected black duration expressed in seconds. It must
1723 be a non-negative floating point number.
1725 Default value is 2.0.
1727 @item picture_black_ratio_th, pic_th
1728 Set the threshold for considering a picture "black".
1729 Express the minimum value for the ratio:
1731 @var{nb_black_pixels} / @var{nb_pixels}
1734 for which a picture is considered black.
1735 Default value is 0.98.
1737 @item pixel_black_th, pix_th
1738 Set the threshold for considering a pixel "black".
1740 The threshold expresses the maximum pixel luminance value for which a
1741 pixel is considered "black". The provided value is scaled according to
1742 the following equation:
1744 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1747 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1748 the input video format, the range is [0-255] for YUV full-range
1749 formats and [16-235] for YUV non full-range formats.
1751 Default value is 0.10.
1754 The following example sets the maximum pixel threshold to the minimum
1755 value, and detects only black intervals of 2 or more seconds:
1757 blackdetect=d=2:pix_th=0.00
1762 Detect frames that are (almost) completely black. Can be useful to
1763 detect chapter transitions or commercials. Output lines consist of
1764 the frame number of the detected frame, the percentage of blackness,
1765 the position in the file if known or -1 and the timestamp in seconds.
1767 In order to display the output lines, you need to set the loglevel at
1768 least to the AV_LOG_INFO value.
1770 The filter accepts the syntax:
1772 blackframe[=@var{amount}:[@var{threshold}]]
1775 @var{amount} is the percentage of the pixels that have to be below the
1776 threshold, and defaults to 98.
1778 @var{threshold} is the threshold below which a pixel value is
1779 considered black, and defaults to 32.
1783 Blend two video frames into each other.
1785 It takes two input streams and outputs one stream, the first input is the
1786 "top" layer and second input is "bottom" layer.
1787 Output terminates when shortest input terminates.
1789 This filter accepts a list of options in the form of @var{key}=@var{value}
1790 pairs separated by ":". A description of the accepted options follows.
1798 Set blend mode for specific pixel component or all pixel components in case
1799 of @var{all_mode}. Default value is @code{normal}.
1801 Available values for component modes are:
1834 Set blend opacity for specific pixel component or all pixel components in case
1835 of @var{all_expr}. Only used in combination with pixel component blend modes.
1842 Set blend expression for specific pixel component or all pixel components in case
1843 of @var{all_expr}. Note that related mode options will be ignored if those are set.
1845 The expressions can use the following variables:
1850 the coordinates of the current sample
1854 the width and height of currently filtered plane
1858 Width and height scale depending on the currently filtered plane. It is the
1859 ratio between the corresponding luma plane number of pixels and the current
1860 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
1861 @code{0.5,0.5} for chroma planes.
1864 Time of the current frame, expressed in seconds.
1867 Value of pixel component at current location for first video frame (top layer).
1870 Value of pixel component at current location for second video frame (bottom layer).
1877 Apply transition from bottom layer to top layer in first 10 seconds:
1879 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
1883 Apply 1x1 checkerboard effect:
1885 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
1891 Apply boxblur algorithm to the input video.
1893 This filter accepts the parameters:
1894 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
1896 Chroma and alpha parameters are optional, if not specified they default
1897 to the corresponding values set for @var{luma_radius} and
1900 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
1901 the radius in pixels of the box used for blurring the corresponding
1902 input plane. They are expressions, and can contain the following
1906 the input width and height in pixels
1909 the input chroma image width and height in pixels
1912 horizontal and vertical chroma subsample values. For example for the
1913 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1916 The radius must be a non-negative number, and must not be greater than
1917 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
1918 and of @code{min(cw,ch)/2} for the chroma planes.
1920 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
1921 how many times the boxblur filter is applied to the corresponding
1924 Some examples follow:
1929 Apply a boxblur filter with luma, chroma, and alpha radius
1936 Set luma radius to 2, alpha and chroma radius to 0
1942 Set luma and chroma radius to a fraction of the video dimension
1944 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
1949 @section colormatrix
1951 The colormatrix filter allows conversion between any of the following color
1952 space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m})
1953 and FCC (@var{fcc}).
1955 The syntax of the parameters is @var{source}:@var{destination}:
1958 colormatrix=bt601:smpte240m
1963 Copy the input source unchanged to the output. Mainly useful for
1968 Crop the input video.
1970 This filter accepts a list of @var{key}=@var{value} pairs as argument,
1971 separated by ':'. If the key of the first options is omitted, the
1972 arguments are interpreted according to the syntax
1973 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
1975 A description of the accepted options follows:
1978 Set the crop area width. It defaults to @code{iw}.
1979 This expression is evaluated only once during the filter
1983 Set the crop area width. It defaults to @code{ih}.
1984 This expression is evaluated only once during the filter
1988 Set the expression for the x top-left coordinate of the cropped area.
1989 It defaults to @code{(in_w-out_w)/2}.
1990 This expression is evaluated per-frame.
1993 Set the expression for the y top-left coordinate of the cropped area.
1994 It defaults to @code{(in_h-out_h)/2}.
1995 This expression is evaluated per-frame.
1998 If set to 1 will force the output display aspect ratio
1999 to be the same of the input, by changing the output sample aspect
2000 ratio. It defaults to 0.
2003 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2004 expressions containing the following constants:
2008 the computed values for @var{x} and @var{y}. They are evaluated for
2012 the input width and height
2015 same as @var{in_w} and @var{in_h}
2018 the output (cropped) width and height
2021 same as @var{out_w} and @var{out_h}
2024 same as @var{iw} / @var{ih}
2027 input sample aspect ratio
2030 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2033 horizontal and vertical chroma subsample values. For example for the
2034 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2037 the number of input frame, starting from 0
2040 the position in the file of the input frame, NAN if unknown
2043 timestamp expressed in seconds, NAN if the input timestamp is unknown
2047 The expression for @var{out_w} may depend on the value of @var{out_h},
2048 and the expression for @var{out_h} may depend on @var{out_w}, but they
2049 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2050 evaluated after @var{out_w} and @var{out_h}.
2052 The @var{x} and @var{y} parameters specify the expressions for the
2053 position of the top-left corner of the output (non-cropped) area. They
2054 are evaluated for each frame. If the evaluated value is not valid, it
2055 is approximated to the nearest valid value.
2057 The expression for @var{x} may depend on @var{y}, and the expression
2058 for @var{y} may depend on @var{x}.
2060 @subsection Examples
2063 Crop area with size 100x100 at position (12,34).
2068 Using named options, the example above becomes:
2070 crop=w=100:h=100:x=12:y=34
2074 Crop the central input area with size 100x100:
2080 Crop the central input area with size 2/3 of the input video:
2082 crop=2/3*in_w:2/3*in_h
2086 Crop the input video central square:
2092 Delimit the rectangle with the top-left corner placed at position
2093 100:100 and the right-bottom corner corresponding to the right-bottom
2094 corner of the input image:
2096 crop=in_w-100:in_h-100:100:100
2100 Crop 10 pixels from the left and right borders, and 20 pixels from
2101 the top and bottom borders
2103 crop=in_w-2*10:in_h-2*20
2107 Keep only the bottom right quarter of the input image:
2109 crop=in_w/2:in_h/2:in_w/2:in_h/2
2113 Crop height for getting Greek harmony:
2115 crop=in_w:1/PHI*in_w
2119 Appply trembling effect:
2121 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)
2125 Apply erratic camera effect depending on timestamp:
2127 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)"
2131 Set x depending on the value of y:
2133 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2139 Auto-detect crop size.
2141 Calculate necessary cropping parameters and prints the recommended
2142 parameters through the logging system. The detected dimensions
2143 correspond to the non-black area of the input video.
2145 It accepts the syntax:
2147 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
2153 Threshold, which can be optionally specified from nothing (0) to
2154 everything (255), defaults to 24.
2157 Value which the width/height should be divisible by, defaults to
2158 16. The offset is automatically adjusted to center the video. Use 2 to
2159 get only even dimensions (needed for 4:2:2 video). 16 is best when
2160 encoding to most video codecs.
2163 Counter that determines after how many frames cropdetect will reset
2164 the previously detected largest video area and start over to detect
2165 the current optimal crop area. Defaults to 0.
2167 This can be useful when channel logos distort the video area. 0
2168 indicates never reset and return the largest area encountered during
2174 Drop frames that do not differ greatly from the previous frame in
2175 order to reduce framerate.
2177 The main use of this filter is for very-low-bitrate encoding
2178 (e.g. streaming over dialup modem), but it could in theory be used for
2179 fixing movies that were inverse-telecined incorrectly.
2181 The filter accepts parameters as a list of @var{key}=@var{value}
2182 pairs, separated by ":". If the key of the first options is omitted,
2183 the arguments are interpreted according to the syntax:
2184 @option{max}:@option{hi}:@option{lo}:@option{frac}.
2186 A description of the accepted options follows.
2190 Set the maximum number of consecutive frames which can be dropped (if
2191 positive), or the minimum interval between dropped frames (if
2192 negative). If the value is 0, the frame is dropped unregarding the
2193 number of previous sequentially dropped frames.
2200 Set the dropping threshold values.
2202 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
2203 represent actual pixel value differences, so a threshold of 64
2204 corresponds to 1 unit of difference for each pixel, or the same spread
2205 out differently over the block.
2207 A frame is a candidate for dropping if no 8x8 blocks differ by more
2208 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
2209 meaning the whole image) differ by more than a threshold of @option{lo}.
2211 Default value for @option{hi} is 64*12, default value for @option{lo} is
2212 64*5, and default value for @option{frac} is 0.33.
2217 Suppress a TV station logo by a simple interpolation of the surrounding
2218 pixels. Just set a rectangle covering the logo and watch it disappear
2219 (and sometimes something even uglier appear - your mileage may vary).
2221 The filter accepts parameters as a string of the form
2222 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
2223 @var{key}=@var{value} pairs, separated by ":".
2225 The description of the accepted parameters follows.
2230 Specify the top left corner coordinates of the logo. They must be
2234 Specify the width and height of the logo to clear. They must be
2238 Specify the thickness of the fuzzy edge of the rectangle (added to
2239 @var{w} and @var{h}). The default value is 4.
2242 When set to 1, a green rectangle is drawn on the screen to simplify
2243 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2244 @var{band} is set to 4. The default value is 0.
2248 Some examples follow.
2253 Set a rectangle covering the area with top left corner coordinates 0,0
2254 and size 100x77, setting a band of size 10:
2256 delogo=0:0:100:77:10
2260 As the previous example, but use named options:
2262 delogo=x=0:y=0:w=100:h=77:band=10
2269 Attempt to fix small changes in horizontal and/or vertical shift. This
2270 filter helps remove camera shake from hand-holding a camera, bumping a
2271 tripod, moving on a vehicle, etc.
2273 The filter accepts parameters as a string of the form
2274 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
2276 A description of the accepted parameters follows.
2281 Specify a rectangular area where to limit the search for motion
2283 If desired the search for motion vectors can be limited to a
2284 rectangular area of the frame defined by its top left corner, width
2285 and height. These parameters have the same meaning as the drawbox
2286 filter which can be used to visualise the position of the bounding
2289 This is useful when simultaneous movement of subjects within the frame
2290 might be confused for camera motion by the motion vector search.
2292 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2293 then the full frame is used. This allows later options to be set
2294 without specifying the bounding box for the motion vector search.
2296 Default - search the whole frame.
2299 Specify the maximum extent of movement in x and y directions in the
2300 range 0-64 pixels. Default 16.
2303 Specify how to generate pixels to fill blanks at the edge of the
2304 frame. An integer from 0 to 3 as follows:
2307 Fill zeroes at blank locations
2309 Original image at blank locations
2311 Extruded edge value at blank locations
2313 Mirrored edge at blank locations
2316 The default setting is mirror edge at blank locations.
2319 Specify the blocksize to use for motion search. Range 4-128 pixels,
2323 Specify the contrast threshold for blocks. Only blocks with more than
2324 the specified contrast (difference between darkest and lightest
2325 pixels) will be considered. Range 1-255, default 125.
2328 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
2329 search. Default - exhaustive search.
2332 If set then a detailed log of the motion search is written to the
2339 Draw a colored box on the input image.
2341 The filter accepts parameters as a list of @var{key}=@var{value}
2342 pairs, separated by ":". If the key of the first options is omitted,
2343 the arguments are interpreted according to the syntax
2344 @option{x}:@option{y}:@option{width}:@option{height}:@option{color}:@option{thickness}.
2346 A description of the accepted options follows.
2350 Specify the top left corner coordinates of the box. Default to 0.
2354 Specify the width and height of the box, if 0 they are interpreted as
2355 the input width and height. Default to 0.
2358 Specify the color of the box to write, it can be the name of a color
2359 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2360 value @code{invert} is used, the box edge color is the same as the
2361 video with inverted luma.
2364 Set the thickness of the box edge. Default value is @code{4}.
2367 Some examples follow:
2370 Draw a black box around the edge of the input image:
2376 Draw a box with color red and an opacity of 50%:
2378 drawbox=10:20:200:60:red@@0.5
2381 The previous example can be specified as:
2383 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2387 Fill the box with pink color:
2389 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2396 Draw text string or text from specified file on top of video using the
2397 libfreetype library.
2399 To enable compilation of this filter you need to configure FFmpeg with
2400 @code{--enable-libfreetype}.
2404 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
2407 The description of the accepted parameters follows.
2412 Used to draw a box around text using background color.
2413 Value should be either 1 (enable) or 0 (disable).
2414 The default value of @var{box} is 0.
2417 The color to be used for drawing box around text.
2418 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2419 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2420 The default value of @var{boxcolor} is "white".
2423 Set an expression which specifies if the text should be drawn. If the
2424 expression evaluates to 0, the text is not drawn. This is useful for
2425 specifying that the text should be drawn only when specific conditions
2428 Default value is "1".
2430 See below for the list of accepted constants and functions.
2433 Select how the @var{text} is expanded. Can be either @code{none},
2434 @code{strftime} (deprecated) or
2435 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2439 If true, check and fix text coords to avoid clipping.
2442 The color to be used for drawing fonts.
2443 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2444 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2445 The default value of @var{fontcolor} is "black".
2448 The font file to be used for drawing text. Path must be included.
2449 This parameter is mandatory.
2452 The font size to be used for drawing text.
2453 The default value of @var{fontsize} is 16.
2456 Flags to be used for loading the fonts.
2458 The flags map the corresponding flags supported by libfreetype, and are
2459 a combination of the following values:
2466 @item vertical_layout
2467 @item force_autohint
2470 @item ignore_global_advance_width
2472 @item ignore_transform
2479 Default value is "render".
2481 For more information consult the documentation for the FT_LOAD_*
2485 The color to be used for drawing a shadow behind the drawn text. It
2486 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2487 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2488 The default value of @var{shadowcolor} is "black".
2490 @item shadowx, shadowy
2491 The x and y offsets for the text shadow position with respect to the
2492 position of the text. They can be either positive or negative
2493 values. Default value for both is "0".
2496 The size in number of spaces to use for rendering the tab.
2500 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2501 format. It can be used with or without text parameter. @var{timecode_rate}
2502 option must be specified.
2504 @item timecode_rate, rate, r
2505 Set the timecode frame rate (timecode only).
2508 The text string to be drawn. The text must be a sequence of UTF-8
2510 This parameter is mandatory if no file is specified with the parameter
2514 A text file containing text to be drawn. The text must be a sequence
2515 of UTF-8 encoded characters.
2517 This parameter is mandatory if no text string is specified with the
2518 parameter @var{text}.
2520 If both @var{text} and @var{textfile} are specified, an error is thrown.
2523 If set to 1, the @var{textfile} will be reloaded before each frame.
2524 Be sure to update it atomically, or it may be read partially, or even fail.
2527 The expressions which specify the offsets where text will be drawn
2528 within the video frame. They are relative to the top/left border of the
2531 The default value of @var{x} and @var{y} is "0".
2533 See below for the list of accepted constants and functions.
2536 The parameters for @var{x} and @var{y} are expressions containing the
2537 following constants and functions:
2541 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2544 horizontal and vertical chroma subsample values. For example for the
2545 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2548 the height of each text line
2556 @item max_glyph_a, ascent
2557 the maximum distance from the baseline to the highest/upper grid
2558 coordinate used to place a glyph outline point, for all the rendered
2560 It is a positive value, due to the grid's orientation with the Y axis
2563 @item max_glyph_d, descent
2564 the maximum distance from the baseline to the lowest grid coordinate
2565 used to place a glyph outline point, for all the rendered glyphs.
2566 This is a negative value, due to the grid's orientation, with the Y axis
2570 maximum glyph height, that is the maximum height for all the glyphs
2571 contained in the rendered text, it is equivalent to @var{ascent} -
2575 maximum glyph width, that is the maximum width for all the glyphs
2576 contained in the rendered text
2579 the number of input frame, starting from 0
2581 @item rand(min, max)
2582 return a random number included between @var{min} and @var{max}
2585 input sample aspect ratio
2588 timestamp expressed in seconds, NAN if the input timestamp is unknown
2591 the height of the rendered text
2594 the width of the rendered text
2597 the x and y offset coordinates where the text is drawn.
2599 These parameters allow the @var{x} and @var{y} expressions to refer
2600 each other, so you can for example specify @code{y=x/dar}.
2603 If libavfilter was built with @code{--enable-fontconfig}, then
2604 @option{fontfile} can be a fontconfig pattern or omitted.
2606 @anchor{drawtext_expansion}
2607 @subsection Text expansion
2609 If @option{expansion} is set to @code{strftime},
2610 the filter recognizes strftime() sequences in the provided text and
2611 expands them accordingly. Check the documentation of strftime(). This
2612 feature is deprecated.
2614 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2616 If @option{expansion} is set to @code{normal} (which is the default),
2617 the following expansion mechanism is used.
2619 The backslash character '\', followed by any character, always expands to
2620 the second character.
2622 Sequence of the form @code{%@{...@}} are expanded. The text between the
2623 braces is a function name, possibly followed by arguments separated by ':'.
2624 If the arguments contain special characters or delimiters (':' or '@}'),
2625 they should be escaped.
2627 Note that they probably must also be escaped as the value for the
2628 @option{text} option in the filter argument string and as the filter
2629 argument in the filter graph description, and possibly also for the shell,
2630 that makes up to four levels of escaping; using a text file avoids these
2633 The following functions are available:
2638 The expression evaluation result.
2640 It must take one argument specifying the expression to be evaluated,
2641 which accepts the same constants and functions as the @var{x} and
2642 @var{y} values. Note that not all constants should be used, for
2643 example the text size is not known when evaluating the expression, so
2644 the constants @var{text_w} and @var{text_h} will have an undefined
2648 The time at which the filter is running, expressed in UTC.
2649 It can accept an argument: a strftime() format string.
2652 The time at which the filter is running, expressed in the local time zone.
2653 It can accept an argument: a strftime() format string.
2656 The frame number, starting from 0.
2659 The timestamp of the current frame, in seconds, with microsecond accuracy.
2663 @subsection Examples
2665 Some examples follow.
2670 Draw "Test Text" with font FreeSerif, using the default values for the
2671 optional parameters.
2674 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2678 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2679 and y=50 (counting from the top-left corner of the screen), text is
2680 yellow with a red box around it. Both the text and the box have an
2684 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2685 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2688 Note that the double quotes are not necessary if spaces are not used
2689 within the parameter list.
2692 Show the text at the center of the video frame:
2694 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2698 Show a text line sliding from right to left in the last row of the video
2699 frame. The file @file{LONG_LINE} is assumed to contain a single line
2702 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2706 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2708 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2712 Draw a single green letter "g", at the center of the input video.
2713 The glyph baseline is placed at half screen height.
2715 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2719 Show text for 1 second every 3 seconds:
2721 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2725 Use fontconfig to set the font. Note that the colons need to be escaped.
2727 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2731 Print the date of a real-time encoding (see strftime(3)):
2733 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
2738 For more information about libfreetype, check:
2739 @url{http://www.freetype.org/}.
2741 For more information about fontconfig, check:
2742 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
2746 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
2748 This filter accepts the following optional named parameters:
2752 Set low and high threshold values used by the Canny thresholding
2755 The high threshold selects the "strong" edge pixels, which are then
2756 connected through 8-connectivity with the "weak" edge pixels selected
2757 by the low threshold.
2759 @var{low} and @var{high} threshold values must be choosen in the range
2760 [0,1], and @var{low} should be lesser or equal to @var{high}.
2762 Default value for @var{low} is @code{20/255}, and default value for @var{high}
2768 edgedetect=low=0.1:high=0.4
2773 Apply fade-in/out effect to input video.
2775 The filter accepts parameters as a list of @var{key}=@var{value}
2776 pairs, separated by ":". If the key of the first options is omitted,
2777 the arguments are interpreted according to the syntax
2778 @var{type}:@var{start_frame}:@var{nb_frames}.
2780 A description of the accepted parameters follows.
2784 Specify if the effect type, can be either @code{in} for fade-in, or
2785 @code{out} for a fade-out effect. Default is @code{in}.
2787 @item start_frame, s
2788 Specify the number of the start frame for starting to apply the fade
2789 effect. Default is 0.
2792 Specify the number of frames for which the fade effect has to last. At
2793 the end of the fade-in effect the output video will have the same
2794 intensity as the input video, at the end of the fade-out transition
2795 the output video will be completely black. Default is 25.
2798 If set to 1, fade only alpha channel, if one exists on the input.
2802 @subsection Examples
2805 Fade in first 30 frames of video:
2810 The command above is equivalent to:
2816 Fade out last 45 frames of a 200-frame video:
2822 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
2824 fade=in:0:25, fade=out:975:25
2828 Make first 5 frames black, then fade in from frame 5-24:
2834 Fade in alpha over first 25 frames of video:
2836 fade=in:0:25:alpha=1
2842 Extract a single field from an interlaced image using stride
2843 arithmetic to avoid wasting CPU time. The output frames are marked as
2846 This filter accepts the following named options:
2849 Specify whether to extract the top (if the value is @code{0} or
2850 @code{top}) or the bottom field (if the value is @code{1} or
2854 If the option key is not specified, the first value sets the @var{type}
2855 option. For example:
2867 Transform the field order of the input video.
2869 It accepts one parameter which specifies the required field order that
2870 the input interlaced video will be transformed to. The parameter can
2871 assume one of the following values:
2875 output bottom field first
2877 output top field first
2880 Default value is "tff".
2882 Transformation is achieved by shifting the picture content up or down
2883 by one line, and filling the remaining line with appropriate picture content.
2884 This method is consistent with most broadcast field order converters.
2886 If the input video is not flagged as being interlaced, or it is already
2887 flagged as being of the required output field order then this filter does
2888 not alter the incoming video.
2890 This filter is very useful when converting to or from PAL DV material,
2891 which is bottom field first.
2895 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
2900 Buffer input images and send them when they are requested.
2902 This filter is mainly useful when auto-inserted by the libavfilter
2905 The filter does not take parameters.
2909 Convert the input video to one of the specified pixel formats.
2910 Libavfilter will try to pick one that is supported for the input to
2913 The filter accepts a list of pixel format names, separated by ":",
2914 for example "yuv420p:monow:rgb24".
2916 Some examples follow:
2918 # convert the input video to the format "yuv420p"
2921 # convert the input video to any of the formats in the list
2922 format=yuv420p:yuv444p:yuv410p
2927 Convert the video to specified constant framerate by duplicating or dropping
2928 frames as necessary.
2930 This filter accepts the following named parameters:
2934 Desired output framerate. The default is @code{25}.
2939 Possible values are:
2942 zero round towards 0
2946 round towards -infinity
2948 round towards +infinity
2952 The default is @code{near}.
2956 Alternatively, the options can be specified as a flat string:
2957 @var{fps}[:@var{round}].
2959 See also the @ref{setpts} filter.
2963 Select one frame every N.
2965 This filter accepts in input a string representing a positive
2966 integer. Default argument is @code{1}.
2971 Apply a frei0r effect to the input video.
2973 To enable compilation of this filter you need to install the frei0r
2974 header and configure FFmpeg with @code{--enable-frei0r}.
2976 The filter supports the syntax:
2978 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
2981 @var{filter_name} is the name of the frei0r effect to load. If the
2982 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
2983 is searched in each one of the directories specified by the colon (or
2984 semicolon on Windows platforms) separated list in @env{FREIOR_PATH},
2985 otherwise in the standard frei0r paths, which are in this order:
2986 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
2987 @file{/usr/lib/frei0r-1/}.
2989 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
2990 for the frei0r effect.
2992 A frei0r effect parameter can be a boolean (whose values are specified
2993 with "y" and "n"), a double, a color (specified by the syntax
2994 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
2995 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
2996 description), a position (specified by the syntax @var{X}/@var{Y},
2997 @var{X} and @var{Y} being float numbers) and a string.
2999 The number and kind of parameters depend on the loaded effect. If an
3000 effect parameter is not specified the default value is set.
3002 Some examples follow:
3006 Apply the distort0r effect, set the first two double parameters:
3008 frei0r=distort0r:0.5:0.01
3012 Apply the colordistance effect, take a color as first parameter:
3014 frei0r=colordistance:0.2/0.3/0.4
3015 frei0r=colordistance:violet
3016 frei0r=colordistance:0x112233
3020 Apply the perspective effect, specify the top left and top right image
3023 frei0r=perspective:0.2/0.2:0.8/0.2
3027 For more information see:
3028 @url{http://frei0r.dyne.org}
3032 The filter takes one, two or three equations as parameter, separated by ':'.
3033 The first equation is mandatory and applies to the luma plane. The two
3034 following are respectively for chroma blue and chroma red planes.
3036 The filter syntax allows named parameters:
3040 the luminance expression
3042 the chrominance blue expression
3044 the chrominance red expression
3047 If one of the chrominance expression is not defined, it falls back on the other
3048 one. If none of them are specified, they will evaluate the luminance
3051 The expressions can use the following variables and functions:
3055 The sequential number of the filtered frame, starting from @code{0}.
3058 The coordinates of the current sample.
3061 The width and height of the image.
3064 Width and height scale depending on the currently filtered plane. It is the
3065 ratio between the corresponding luma plane number of pixels and the current
3066 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3067 @code{0.5,0.5} for chroma planes.
3070 Time of the current frame, expressed in seconds.
3073 Return the value of the pixel at location (@var{x},@var{y}) of the current
3077 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3081 Return the value of the pixel at location (@var{x},@var{y}) of the
3082 blue-difference chroma plane.
3085 Return the value of the pixel at location (@var{x},@var{y}) of the
3086 red-difference chroma plane.
3089 For functions, if @var{x} and @var{y} are outside the area, the value will be
3090 automatically clipped to the closer edge.
3092 Some examples follow:
3096 Flip the image horizontally:
3102 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3103 wavelength of 100 pixels:
3105 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3109 Generate a fancy enigmatic moving light:
3111 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
3117 Fix the banding artifacts that are sometimes introduced into nearly flat
3118 regions by truncation to 8bit color depth.
3119 Interpolate the gradients that should go where the bands are, and
3122 This filter is designed for playback only. Do not use it prior to
3123 lossy compression, because compression tends to lose the dither and
3124 bring back the bands.
3126 The filter accepts a list of options in the form of @var{key}=@var{value} pairs
3127 separated by ":". A description of the accepted options follows.
3132 The maximum amount by which the filter will change
3133 any one pixel. Also the threshold for detecting nearly flat
3134 regions. Acceptable values range from @code{0.51} to @code{64}, default value
3138 The neighborhood to fit the gradient to. A larger
3139 radius makes for smoother gradients, but also prevents the filter from
3140 modifying the pixels near detailed regions. Acceptable values are
3141 @code{8-32}, default value is @code{16}.
3145 Alternatively, the options can be specified as a flat string:
3146 @var{strength}[:@var{radius}]
3148 @subsection Examples
3152 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3158 Specify radius, omitting the strength (which will fall-back to the default
3168 Flip the input video horizontally.
3170 For example to horizontally flip the input video with @command{ffmpeg}:
3172 ffmpeg -i in.avi -vf "hflip" out.avi
3176 This filter applies a global color histogram equalization on a
3179 It can be used to correct video that has a compressed range of pixel
3180 intensities. The filter redistributes the pixel intensities to
3181 equalize their distribution across the intensity range. It may be
3182 viewed as an "automatically adjusting contrast filter". This filter is
3183 useful only for correcting degraded or poorly captured source
3186 The filter accepts parameters as a list of @var{key}=@var{value}
3187 pairs, separated by ":". If the key of the first options is omitted,
3188 the arguments are interpreted according to syntax
3189 @var{strength}:@var{intensity}:@var{antibanding}.
3191 This filter accepts the following named options:
3195 Determine the amount of equalization to be applied. As the strength
3196 is reduced, the distribution of pixel intensities more-and-more
3197 approaches that of the input frame. The value must be a float number
3198 in the range [0,1] and defaults to 0.200.
3201 Set the maximum intensity that can generated and scale the output
3202 values appropriately. The strength should be set as desired and then
3203 the intensity can be limited if needed to avoid washing-out. The value
3204 must be a float number in the range [0,1] and defaults to 0.210.
3207 Set the antibanding level. If enabled the filter will randomly vary
3208 the luminance of output pixels by a small amount to avoid banding of
3209 the histogram. Possible values are @code{none}, @code{weak} or
3210 @code{strong}. It defaults to @code{none}.
3215 Compute and draw a color distribution histogram for the input video.
3217 The computed histogram is a representation of distribution of color components
3220 The filter accepts the following named parameters:
3226 It accepts the following values:
3229 standard histogram that display color components distribution in an image.
3230 Displays color graph for each color component. Shows distribution
3231 of the Y, U, V, A or G, B, R components, depending on input format,
3232 in current frame. Bellow each graph is color component scale meter.
3235 chroma values in vectorscope, if brighter more such chroma values are
3236 distributed in an image.
3237 Displays chroma values (U/V color placement) in two dimensional graph
3238 (which is called a vectorscope). It can be used to read of the hue and
3239 saturation of the current frame. At a same time it is a histogram.
3240 The whiter a pixel in the vectorscope, the more pixels of the input frame
3241 correspond to that pixel (that is the more pixels have this chroma value).
3242 The V component is displayed on the horizontal (X) axis, with the leftmost
3243 side being V = 0 and the rightmost side being V = 255.
3244 The U component is displayed on the vertical (Y) axis, with the top
3245 representing U = 0 and the bottom representing U = 255.
3247 The position of a white pixel in the graph corresponds to the chroma value
3248 of a pixel of the input clip. So the graph can be used to read of the
3249 hue (color flavor) and the saturation (the dominance of the hue in the color).
3250 As the hue of a color changes, it moves around the square. At the center of
3251 the square, the saturation is zero, which means that the corresponding pixel
3252 has no color. If you increase the amount of a specific color, while leaving
3253 the other colors unchanged, the saturation increases, and you move towards
3254 the edge of the square.
3257 chroma values in vectorscope, similar as @code{color} but actual chroma values
3261 per row/column color component graph. In row mode graph in the left side represents
3262 color component value 0 and right side represents value = 255. In column mode top
3263 side represents color component value = 0 and bottom side represents value = 255.
3265 Default value is @code{levels}.
3268 Set height of level in @code{levels}. Default value is @code{200}.
3269 Allowed range is [50, 2048].
3272 Set height of color scale in @code{levels}. Default value is @code{12}.
3273 Allowed range is [0, 40].
3276 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3277 of same luminance values across input rows/columns are distributed.
3278 Default value is @code{10}. Allowed range is [1, 255].
3281 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3282 Default is @code{row}.
3285 Set display mode for @code{waveform} and @code{levels}.
3286 It accepts the following values:
3289 Display separate graph for the color components side by side in
3290 @code{row} waveform mode or one below other in @code{column} waveform mode
3291 for @code{waveform} histogram mode. For @code{levels} histogram mode
3292 per color component graphs are placed one bellow other.
3294 This display mode in @code{waveform} histogram mode makes it easy to spot
3295 color casts in the highlights and shadows of an image, by comparing the
3296 contours of the top and the bottom of each waveform.
3297 Since whites, grays, and blacks are characterized by
3298 exactly equal amounts of red, green, and blue, neutral areas of the
3299 picture should display three waveforms of roughly equal width/height.
3300 If not, the correction is easy to make by making adjustments to level the
3304 Presents information that's identical to that in the @code{parade}, except
3305 that the graphs representing color components are superimposed directly
3308 This display mode in @code{waveform} histogram mode can make it easier to spot
3309 the relative differences or similarities in overlapping areas of the color
3310 components that are supposed to be identical, such as neutral whites, grays,
3313 Default is @code{parade}.
3316 @subsection Examples
3321 Calculate and draw histogram:
3323 ffplay -i input -vf histogram
3330 High precision/quality 3d denoise filter. This filter aims to reduce
3331 image noise producing smooth images and making still images really
3332 still. It should enhance compressibility.
3334 It accepts the following optional parameters:
3335 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
3339 a non-negative float number which specifies spatial luma strength,
3342 @item chroma_spatial
3343 a non-negative float number which specifies spatial chroma strength,
3344 defaults to 3.0*@var{luma_spatial}/4.0
3347 a float number which specifies luma temporal strength, defaults to
3348 6.0*@var{luma_spatial}/4.0
3351 a float number which specifies chroma temporal strength, defaults to
3352 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3357 Modify the hue and/or the saturation of the input.
3359 This filter accepts the following optional named options:
3363 Specify the hue angle as a number of degrees. It accepts a float
3364 number or an expression, and defaults to 0.0.
3367 Specify the hue angle as a number of degrees. It accepts a float
3368 number or an expression, and defaults to 0.0.
3371 Specify the saturation in the [-10,10] range. It accepts a float number and
3375 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3376 following constants:
3380 frame count of the input frame starting from 0
3383 presentation timestamp of the input frame expressed in time base units
3386 frame rate of the input video, NAN if the input frame rate is unknown
3389 timestamp expressed in seconds, NAN if the input timestamp is unknown
3392 time base of the input video
3395 The options can also be set using the syntax: @var{hue}:@var{saturation}
3397 In this case @var{hue} is expressed in degrees.
3399 Some examples follow:
3402 Set the hue to 90 degrees and the saturation to 1.0:
3408 Same command but expressing the hue in radians:
3414 Same command without named options, hue must be expressed in degrees:
3420 Note that "h:s" syntax does not support expressions for the values of
3421 h and s, so the following example will issue an error:
3427 Rotate hue and make the saturation swing between 0
3428 and 2 over a period of 1 second:
3430 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3434 Apply a 3 seconds saturation fade-in effect starting at 0:
3439 The general fade-in expression can be written as:
3441 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3445 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3447 hue="s=max(0\, min(1\, (8-t)/3))"
3450 The general fade-out expression can be written as:
3452 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3457 @subsection Commands
3459 This filter supports the following command:
3462 Modify the hue and/or the saturation of the input video.
3463 The command accepts the same named options and syntax than when calling the
3464 filter from the command-line.
3466 If a parameter is omitted, it is kept at its current value.
3471 Detect video interlacing type.
3473 This filter tries to detect if the input is interlaced or progressive,
3474 top or bottom field first.
3478 Deinterleave or interleave fields.
3480 This filter allows to process interlaced images fields without
3481 deinterlacing them. Deinterleaving splits the input frame into 2
3482 fields (so called half pictures). Odd lines are moved to the top
3483 half of the output image, even lines to the bottom half.
3484 You can process (filter) them independently and then re-interleave them.
3486 It accepts a list of options in the form of @var{key}=@var{value} pairs
3487 separated by ":". A description of the accepted options follows.
3491 @item chroma_mode, s
3493 Available values for @var{luma_mode}, @var{chroma_mode} and
3494 @var{alpha_mode} are:
3500 @item deinterleave, d
3501 Deinterleave fields, placing one above the other.
3504 Interleave fields. Reverse the effect of deinterleaving.
3506 Default value is @code{none}.
3509 @item chroma_swap, cs
3510 @item alpha_swap, as
3511 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3516 Deinterlace input video by applying Donald Graft's adaptive kernel
3517 deinterling. Work on interlaced parts of a video to produce
3520 This filter accepts parameters as a list of @var{key}=@var{value}
3521 pairs, separated by ":". If the key of the first options is omitted,
3522 the arguments are interpreted according to the following syntax:
3523 @var{thresh}:@var{map}:@var{order}:@var{sharp}:@var{twoway}.
3525 The description of the accepted parameters follows.
3529 Set the threshold which affects the filter's tolerance when
3530 determining if a pixel line must be processed. It must be an integer
3531 in the range [0,255] and defaults to 10. A value of 0 will result in
3532 applying the process on every pixels.
3535 Paint pixels exceeding the threshold value to white if set to 1.
3539 Set the fields order. Swap fields if set to 1, leave fields alone if
3543 Enable additional sharpening if set to 1. Default is 0.
3546 Enable twoway sharpening if set to 1. Default is 0.
3549 @subsection Examples
3553 Apply default values:
3555 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3559 Enable additional sharpening:
3565 Paint processed pixels in white:
3571 @section lut, lutrgb, lutyuv
3573 Compute a look-up table for binding each pixel component input value
3574 to an output value, and apply it to input video.
3576 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3577 to an RGB input video.
3579 These filters accept in input a ":"-separated list of options, which
3580 specify the expressions used for computing the lookup table for the
3581 corresponding pixel component values.
3583 The @var{lut} filter requires either YUV or RGB pixel formats in
3584 input, and accepts the options:
3587 set first pixel component expression
3589 set second pixel component expression
3591 set third pixel component expression
3593 set fourth pixel component expression, corresponds to the alpha component
3596 The exact component associated to each option depends on the format in
3599 The @var{lutrgb} filter requires RGB pixel formats in input, and
3600 accepts the options:
3603 set red component expression
3605 set green component expression
3607 set blue component expression
3609 alpha component expression
3612 The @var{lutyuv} filter requires YUV pixel formats in input, and
3613 accepts the options:
3616 set Y/luminance component expression
3618 set U/Cb component expression
3620 set V/Cr component expression
3622 set alpha component expression
3625 The expressions can contain the following constants and functions:
3629 the input width and height
3632 input value for the pixel component
3635 the input value clipped in the @var{minval}-@var{maxval} range
3638 maximum value for the pixel component
3641 minimum value for the pixel component
3644 the negated value for the pixel component value clipped in the
3645 @var{minval}-@var{maxval} range , it corresponds to the expression
3646 "maxval-clipval+minval"
3649 the computed value in @var{val} clipped in the
3650 @var{minval}-@var{maxval} range
3652 @item gammaval(gamma)
3653 the computed gamma correction value of the pixel component value
3654 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3656 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3660 All expressions default to "val".
3662 @subsection Examples
3668 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3669 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3672 The above is the same as:
3674 lutrgb="r=negval:g=negval:b=negval"
3675 lutyuv="y=negval:u=negval:v=negval"
3685 Remove chroma components, turns the video into a graytone image:
3687 lutyuv="u=128:v=128"
3691 Apply a luma burning effect:
3697 Remove green and blue components:
3703 Set a constant alpha channel value on input:
3705 format=rgba,lutrgb=a="maxval-minval/2"
3709 Correct luminance gamma by a 0.5 factor:
3711 lutyuv=y=gammaval(0.5)
3717 Apply an MPlayer filter to the input video.
3719 This filter provides a wrapper around most of the filters of
3722 This wrapper is considered experimental. Some of the wrapped filters
3723 may not work properly and we may drop support for them, as they will
3724 be implemented natively into FFmpeg. Thus you should avoid
3725 depending on them when writing portable scripts.
3727 The filters accepts the parameters:
3728 @var{filter_name}[:=]@var{filter_params}
3730 @var{filter_name} is the name of a supported MPlayer filter,
3731 @var{filter_params} is a string containing the parameters accepted by
3734 The list of the currently supported filters follows:
3762 The parameter syntax and behavior for the listed filters are the same
3763 of the corresponding MPlayer filters. For detailed instructions check
3764 the "VIDEO FILTERS" section in the MPlayer manual.
3766 Some examples follow:
3769 Adjust gamma, brightness, contrast:
3775 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
3781 This filter accepts an integer in input, if non-zero it negates the
3782 alpha component (if available). The default value in input is 0.
3786 Force libavfilter not to use any of the specified pixel formats for the
3787 input to the next filter.
3789 The filter accepts a list of pixel format names, separated by ":",
3790 for example "yuv420p:monow:rgb24".
3792 Some examples follow:
3794 # force libavfilter to use a format different from "yuv420p" for the
3795 # input to the vflip filter
3796 noformat=yuv420p,vflip
3798 # convert the input video to any of the formats not contained in the list
3799 noformat=yuv420p:yuv444p:yuv410p
3804 Add noise on video input frame.
3806 This filter accepts a list of options in the form of @var{key}=@var{value}
3807 pairs separated by ":". A description of the accepted options follows.
3815 Set noise seed for specific pixel component or all pixel components in case
3816 of @var{all_seed}. Default value is @code{123457}.
3818 @item all_strength, as
3819 @item c0_strength, c0s
3820 @item c1_strength, c1s
3821 @item c2_strength, c2s
3822 @item c3_strength, c3s
3823 Set noise strength for specific pixel component or all pixel components in case
3824 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
3831 Set pixel component flags or set flags for all components if @var{all_flags}.
3832 Available values for component flags are:
3835 averaged temporal noise (smoother)
3837 mix random noise with a (semi)regular pattern
3839 higher quality (slightly better looking, slightly slower)
3841 temporal noise (noise pattern changes between frames)
3843 uniform noise (gaussian otherwise)
3847 Some examples follow:
3849 Add temporal and uniform noise to input video:
3850 noise=alls=20:allf=t+u
3855 Pass the video source unchanged to the output.
3859 Apply video transform using libopencv.
3861 To enable this filter install libopencv library and headers and
3862 configure FFmpeg with @code{--enable-libopencv}.
3864 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
3866 @var{filter_name} is the name of the libopencv filter to apply.
3868 @var{filter_params} specifies the parameters to pass to the libopencv
3869 filter. If not specified the default values are assumed.
3871 Refer to the official libopencv documentation for more precise
3873 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
3875 Follows the list of supported libopencv filters.
3880 Dilate an image by using a specific structuring element.
3881 This filter corresponds to the libopencv function @code{cvDilate}.
3883 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
3885 @var{struct_el} represents a structuring element, and has the syntax:
3886 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
3888 @var{cols} and @var{rows} represent the number of columns and rows of
3889 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
3890 point, and @var{shape} the shape for the structuring element, and
3891 can be one of the values "rect", "cross", "ellipse", "custom".
3893 If the value for @var{shape} is "custom", it must be followed by a
3894 string of the form "=@var{filename}". The file with name
3895 @var{filename} is assumed to represent a binary image, with each
3896 printable character corresponding to a bright pixel. When a custom
3897 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
3898 or columns and rows of the read file are assumed instead.
3900 The default value for @var{struct_el} is "3x3+0x0/rect".
3902 @var{nb_iterations} specifies the number of times the transform is
3903 applied to the image, and defaults to 1.
3905 Follow some example:
3907 # use the default values
3910 # dilate using a structuring element with a 5x5 cross, iterate two times
3911 ocv=dilate=5x5+2x2/cross:2
3913 # read the shape from the file diamond.shape, iterate two times
3914 # the file diamond.shape may contain a pattern of characters like this:
3920 # the specified cols and rows are ignored (but not the anchor point coordinates)
3921 ocv=0x0+2x2/custom=diamond.shape:2
3926 Erode an image by using a specific structuring element.
3927 This filter corresponds to the libopencv function @code{cvErode}.
3929 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
3930 with the same syntax and semantics as the @ref{dilate} filter.
3934 Smooth the input video.
3936 The filter takes the following parameters:
3937 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
3939 @var{type} is the type of smooth filter to apply, and can be one of
3940 the following values: "blur", "blur_no_scale", "median", "gaussian",
3941 "bilateral". The default value is "gaussian".
3943 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
3944 parameters whose meanings depend on smooth type. @var{param1} and
3945 @var{param2} accept integer positive values or 0, @var{param3} and
3946 @var{param4} accept float values.
3948 The default value for @var{param1} is 3, the default value for the
3949 other parameters is 0.
3951 These parameters correspond to the parameters assigned to the
3952 libopencv function @code{cvSmooth}.
3957 Overlay one video on top of another.
3959 It takes two inputs and one output, the first input is the "main"
3960 video on which the second input is overlayed.
3962 This filter accepts a list of @var{key}=@var{value} pairs as argument,
3963 separated by ":". If the key of the first options is omitted, the
3964 arguments are interpreted according to the syntax @var{x}:@var{y}.
3966 A description of the accepted options follows.
3970 Set the expression for the x and y coordinates of the overlayed video
3971 on the main video. Default value is 0.
3973 The @var{x} and @var{y} expressions can contain the following
3976 @item main_w, main_h
3977 main input width and height
3980 same as @var{main_w} and @var{main_h}
3982 @item overlay_w, overlay_h
3983 overlay input width and height
3986 same as @var{overlay_w} and @var{overlay_h}
3990 Set the format for the output video.
3992 It accepts the following values:
4004 Default value is @samp{yuv420}.
4006 @item rgb @emph{(deprecated)}
4007 If set to 1, force the filter to accept inputs in the RGB
4008 color space. Default value is 0. This option is deprecated, use
4009 @option{format} instead.
4012 If set to 1, force the output to terminate when the shortest input
4013 terminates. Default value is 0.
4016 Be aware that frames are taken from each input video in timestamp
4017 order, hence, if their initial timestamps differ, it is a a good idea
4018 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4019 have them begin in the same zero timestamp, as it does the example for
4020 the @var{movie} filter.
4022 You can chain together more overlays but you should test the
4023 efficiency of such approach.
4025 @subsection Examples
4029 Draw the overlay at 10 pixels from the bottom right corner of the main
4032 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4035 Using named options the example above becomes:
4037 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4041 Insert a transparent PNG logo in the bottom left corner of the input,
4042 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4044 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4048 Insert 2 different transparent PNG logos (second logo on bottom
4049 right corner) using the @command{ffmpeg} tool:
4051 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
4055 Add a transparent color layer on top of the main video, WxH specifies
4056 the size of the main input to the overlay filter:
4058 color=red@@.3:WxH [over]; [in][over] overlay [out]
4062 Play an original video and a filtered version (here with the deshake
4063 filter) side by side using the @command{ffplay} tool:
4065 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4068 The above command is the same as:
4070 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4074 Compose output by putting two input videos side to side:
4076 ffmpeg -i left.avi -i right.avi -filter_complex "
4077 nullsrc=size=200x100 [background];
4078 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4079 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4080 [background][left] overlay=shortest=1 [background+left];
4081 [background+left][right] overlay=shortest=1:x=100 [left+right]
4086 Chain several overlays in cascade:
4088 nullsrc=s=200x200 [bg];
4089 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4090 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4091 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4092 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4093 [in3] null, [mid2] overlay=100:100 [out0]
4100 Add paddings to the input image, and place the original input at the
4101 given coordinates @var{x}, @var{y}.
4103 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
4106 If the key of the first options is omitted, the arguments are
4107 interpreted according to the syntax
4108 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
4110 A description of the accepted options follows.
4115 Specify an expression for the size of the output image with the
4116 paddings added. If the value for @var{width} or @var{height} is 0, the
4117 corresponding input size is used for the output.
4119 The @var{width} expression can reference the value set by the
4120 @var{height} expression, and vice versa.
4122 The default value of @var{width} and @var{height} is 0.
4126 Specify an expression for the offsets where to place the input image
4127 in the padded area with respect to the top/left border of the output
4130 The @var{x} expression can reference the value set by the @var{y}
4131 expression, and vice versa.
4133 The default value of @var{x} and @var{y} is 0.
4136 Specify the color of the padded area, it can be the name of a color
4137 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4139 The default value of @var{color} is "black".
4142 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4143 options are expressions containing the following constants:
4147 the input video width and height
4150 same as @var{in_w} and @var{in_h}
4153 the output width and height, that is the size of the padded area as
4154 specified by the @var{width} and @var{height} expressions
4157 same as @var{out_w} and @var{out_h}
4160 x and y offsets as specified by the @var{x} and @var{y}
4161 expressions, or NAN if not yet specified
4164 same as @var{iw} / @var{ih}
4167 input sample aspect ratio
4170 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4173 horizontal and vertical chroma subsample values. For example for the
4174 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4177 @subsection Examples
4181 Add paddings with color "violet" to the input video. Output video
4182 size is 640x480, the top-left corner of the input video is placed at
4185 pad=640:480:0:40:violet
4188 The example above is equivalent to the following command:
4190 pad=width=640:height=480:x=0:y=40:color=violet
4194 Pad the input to get an output with dimensions increased by 3/2,
4195 and put the input video at the center of the padded area:
4197 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4201 Pad the input to get a squared output with size equal to the maximum
4202 value between the input width and height, and put the input video at
4203 the center of the padded area:
4205 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4209 Pad the input to get a final w/h ratio of 16:9:
4211 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4215 In case of anamorphic video, in order to set the output display aspect
4216 correctly, it is necessary to use @var{sar} in the expression,
4217 according to the relation:
4219 (ih * X / ih) * sar = output_dar
4220 X = output_dar / sar
4223 Thus the previous example needs to be modified to:
4225 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4229 Double output size and put the input video in