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.
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
653 Fade in first 15 seconds of audio:
659 Fade out last 25 seconds of a 900 seconds audio:
661 afade=t=out:ss=875:d=25
667 Set output format constraints for the input audio. The framework will
668 negotiate the most appropriate format to minimize conversions.
670 The filter accepts the following named parameters:
674 A comma-separated list of requested sample formats.
677 A comma-separated list of requested sample rates.
679 @item channel_layouts
680 A comma-separated list of requested channel layouts.
684 If a parameter is omitted, all values are allowed.
686 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
688 aformat='sample_fmts=u8,s16:channel_layouts=stereo'
693 Merge two or more audio streams into a single multi-channel stream.
695 The filter accepts the following named options:
700 Set the number of inputs. Default is 2.
704 If the channel layouts of the inputs are disjoint, and therefore compatible,
705 the channel layout of the output will be set accordingly and the channels
706 will be reordered as necessary. If the channel layouts of the inputs are not
707 disjoint, the output will have all the channels of the first input then all
708 the channels of the second input, in that order, and the channel layout of
709 the output will be the default value corresponding to the total number of
712 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
713 is FC+BL+BR, then the output will be in 5.1, with the channels in the
714 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
715 first input, b1 is the first channel of the second input).
717 On the other hand, if both input are in stereo, the output channels will be
718 in the default order: a1, a2, b1, b2, and the channel layout will be
719 arbitrarily set to 4.0, which may or may not be the expected value.
721 All inputs must have the same sample rate, and format.
723 If inputs do not have the same duration, the output will stop with the
730 Merge two mono files into a stereo stream:
732 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
739 amovie=input.mkv:si=0 [a0];
740 amovie=input.mkv:si=1 [a1];
741 amovie=input.mkv:si=2 [a2];
742 amovie=input.mkv:si=3 [a3];
743 amovie=input.mkv:si=4 [a4];
744 amovie=input.mkv:si=5 [a5];
745 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
751 Mixes multiple audio inputs into a single output.
755 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
757 will mix 3 input audio streams to a single output with the same duration as the
758 first input and a dropout transition time of 3 seconds.
760 The filter accepts the following named parameters:
764 Number of inputs. If unspecified, it defaults to 2.
767 How to determine the end-of-stream.
771 Duration of longest input. (default)
774 Duration of shortest input.
777 Duration of first input.
781 @item dropout_transition
782 Transition time, in seconds, for volume renormalization when an input
783 stream ends. The default value is 2 seconds.
789 Pass the audio source unchanged to the output.
793 Pad the end of a audio stream with silence, this can be used together with
794 -shortest to extend audio streams to the same length as the video stream.
799 Resample the input audio to the specified parameters, using the
800 libswresample library. If none are specified then the filter will
801 automatically convert between its input and output.
803 This filter is also able to stretch/squeeze the audio data to make it match
804 the timestamps or to inject silence / cut out audio to make it match the
805 timestamps, do a combination of both or do neither.
807 The filter accepts the syntax
808 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
809 expresses a sample rate and @var{resampler_options} is a list of
810 @var{key}=@var{value} pairs, separated by ":". See the
811 ffmpeg-resampler manual for the complete list of supported options.
817 Resample the input audio to 44100Hz:
823 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
824 samples per second compensation:
830 @section asetnsamples
832 Set the number of samples per each output audio frame.
834 The last output packet may contain a different number of samples, as
835 the filter will flush all the remaining samples when the input audio
838 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
843 @item nb_out_samples, n
844 Set the number of frames per each output audio frame. The number is
845 intended as the number of samples @emph{per each channel}.
846 Default value is 1024.
849 If set to 1, the filter will pad the last audio frame with zeroes, so
850 that the last frame will contain the same number of samples as the
851 previous ones. Default value is 1.
854 For example, to set the number of per-frame samples to 1234 and
855 disable padding for the last frame, use:
857 asetnsamples=n=1234:p=0
862 Show a line containing various information for each input audio frame.
863 The input audio is not modified.
865 The shown line contains a sequence of key/value pairs of the form
866 @var{key}:@var{value}.
868 A description of each shown parameter follows:
872 sequential number of the input frame, starting from 0
875 Presentation timestamp of the input frame, in time base units; the time base
876 depends on the filter input pad, and is usually 1/@var{sample_rate}.
879 presentation timestamp of the input frame in seconds
882 position of the frame in the input stream, -1 if this information in
883 unavailable and/or meaningless (for example in case of synthetic audio)
892 sample rate for the audio frame
895 number of samples (per channel) in the frame
898 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
899 the data is treated as if all the planes were concatenated.
901 @item plane_checksums
902 A list of Adler-32 checksums for each data plane.
907 Split input audio into several identical outputs.
909 The filter accepts a single parameter which specifies the number of outputs. If
910 unspecified, it defaults to 2.
914 [in] asplit [out0][out1]
917 will create two separate outputs from the same input.
919 To create 3 or more outputs, you need to specify the number of
922 [in] asplit=3 [out0][out1][out2]
926 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
928 will create 5 copies of the input audio.
933 Forward two audio streams and control the order the buffers are forwarded.
935 The argument to the filter is an expression deciding which stream should be
936 forwarded next: if the result is negative, the first stream is forwarded; if
937 the result is positive or zero, the second stream is forwarded. It can use
938 the following variables:
942 number of buffers forwarded so far on each stream
944 number of samples forwarded so far on each stream
946 current timestamp of each stream
949 The default value is @code{t1-t2}, which means to always forward the stream
950 that has a smaller timestamp.
952 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
953 input, while avoiding too much of a desynchronization:
955 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
956 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
964 The filter accepts exactly one parameter, the audio tempo. If not
965 specified then the filter will assume nominal 1.0 tempo. Tempo must
966 be in the [0.5, 2.0] range.
972 Slow down audio to 80% tempo:
978 To speed up audio to 125% tempo:
986 Make audio easier to listen to on headphones.
988 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
989 so that when listened to on headphones the stereo image is moved from
990 inside your head (standard for headphones) to outside and in front of
991 the listener (standard for speakers).
997 Mix channels with specific gain levels. The filter accepts the output
998 channel layout followed by a set of channels definitions.
1000 This filter is also designed to remap efficiently the channels of an audio
1003 The filter accepts parameters of the form:
1004 "@var{l}:@var{outdef}:@var{outdef}:..."
1008 output channel layout or number of channels
1011 output channel specification, of the form:
1012 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1015 output channel to define, either a channel name (FL, FR, etc.) or a channel
1016 number (c0, c1, etc.)
1019 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1022 input channel to use, see out_name for details; it is not possible to mix
1023 named and numbered input channels
1026 If the `=' in a channel specification is replaced by `<', then the gains for
1027 that specification will be renormalized so that the total is 1, thus
1028 avoiding clipping noise.
1030 @subsection Mixing examples
1032 For example, if you want to down-mix from stereo to mono, but with a bigger
1033 factor for the left channel:
1035 pan=1:c0=0.9*c0+0.1*c1
1038 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1039 7-channels surround:
1041 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1044 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1045 that should be preferred (see "-ac" option) unless you have very specific
1048 @subsection Remapping examples
1050 The channel remapping will be effective if, and only if:
1053 @item gain coefficients are zeroes or ones,
1054 @item only one input per channel output,
1057 If all these conditions are satisfied, the filter will notify the user ("Pure
1058 channel mapping detected"), and use an optimized and lossless method to do the
1061 For example, if you have a 5.1 source and want a stereo audio stream by
1062 dropping the extra channels:
1064 pan="stereo: c0=FL : c1=FR"
1067 Given the same source, you can also switch front left and front right channels
1068 and keep the input channel layout:
1070 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1073 If the input is a stereo audio stream, you can mute the front left channel (and
1074 still keep the stereo channel layout) with:
1079 Still with a stereo audio stream input, you can copy the right channel in both
1080 front left and right:
1082 pan="stereo: c0=FR : c1=FR"
1085 @section silencedetect
1087 Detect silence in an audio stream.
1089 This filter logs a message when it detects that the input audio volume is less
1090 or equal to a noise tolerance value for a duration greater or equal to the
1091 minimum detected noise duration.
1093 The printed times and duration are expressed in seconds.
1097 Set silence duration until notification (default is 2 seconds).
1100 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1101 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1104 @subsection Examples
1108 Detect 5 seconds of silence with -50dB noise tolerance:
1110 silencedetect=n=-50dB:d=5
1114 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1115 tolerance in @file{silence.mp3}:
1117 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
1122 Synchronize audio data with timestamps by squeezing/stretching it and/or
1123 dropping samples/adding silence when needed.
1125 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1127 The filter accepts the following named parameters:
1131 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1132 by default. When disabled, time gaps are covered with silence.
1135 Minimum difference between timestamps and audio data (in seconds) to trigger
1136 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1137 this filter, try setting this parameter to 0.
1140 Maximum compensation in samples per second. Relevant only with compensate=1.
1144 Assume the first pts should be this value. The time base is 1 / sample rate.
1145 This allows for padding/trimming at the start of stream. By default, no
1146 assumption is made about the first frame's expected pts, so no padding or
1147 trimming is done. For example, this could be set to 0 to pad the beginning with
1148 silence if an audio stream starts after the video stream or to trim any samples
1149 with a negative pts due to encoder delay.
1153 @section channelsplit
1154 Split each channel in input audio stream into a separate output stream.
1156 This filter accepts the following named parameters:
1158 @item channel_layout
1159 Channel layout of the input stream. Default is "stereo".
1162 For example, assuming a stereo input MP3 file
1164 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1166 will create an output Matroska file with two audio streams, one containing only
1167 the left channel and the other the right channel.
1169 To split a 5.1 WAV file into per-channel files
1171 ffmpeg -i in.wav -filter_complex
1172 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1173 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1174 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1179 Remap input channels to new locations.
1181 This filter accepts the following named parameters:
1183 @item channel_layout
1184 Channel layout of the output stream.
1187 Map channels from input to output. The argument is a comma-separated list of
1188 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1189 @var{in_channel} form. @var{in_channel} can be either the name of the input
1190 channel (e.g. FL for front left) or its index in the input channel layout.
1191 @var{out_channel} is the name of the output channel or its index in the output
1192 channel layout. If @var{out_channel} is not given then it is implicitly an
1193 index, starting with zero and increasing by one for each mapping.
1196 If no mapping is present, the filter will implicitly map input channels to
1197 output channels preserving index.
1199 For example, assuming a 5.1+downmix input MOV file
1201 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
1203 will create an output WAV file tagged as stereo from the downmix channels of
1206 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1208 ffmpeg -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
1212 Join multiple input streams into one multi-channel stream.
1214 The filter accepts the following named parameters:
1218 Number of input streams. Defaults to 2.
1220 @item channel_layout
1221 Desired output channel layout. Defaults to stereo.
1224 Map channels from inputs to output. The argument is a comma-separated list of
1225 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1226 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1227 can be either the name of the input channel (e.g. FL for front left) or its
1228 index in the specified input stream. @var{out_channel} is the name of the output
1232 The filter will attempt to guess the mappings when those are not specified
1233 explicitly. It does so by first trying to find an unused matching input channel
1234 and if that fails it picks the first unused input channel.
1236 E.g. to join 3 inputs (with properly set channel layouts)
1238 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1241 To build a 5.1 output from 6 single-channel streams:
1243 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1244 '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'
1249 Convert the audio sample format, sample rate and channel layout. This filter is
1250 not meant to be used directly.
1254 Adjust the input audio volume.
1256 The filter accepts the following named parameters. If the key of the
1257 first options is omitted, the arguments are interpreted according to
1258 the following syntax:
1260 volume=@var{volume}:@var{precision}
1266 Expresses how the audio volume will be increased or decreased.
1268 Output values are clipped to the maximum value.
1270 The output audio volume is given by the relation:
1272 @var{output_volume} = @var{volume} * @var{input_volume}
1275 Default value for @var{volume} is 1.0.
1278 Set the mathematical precision.
1280 This determines which input sample formats will be allowed, which affects the
1281 precision of the volume scaling.
1285 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1287 32-bit floating-point; limits input sample format to FLT. (default)
1289 64-bit floating-point; limits input sample format to DBL.
1293 @subsection Examples
1297 Halve the input audio volume:
1301 volume=volume=-6.0206dB
1304 In all the above example the named key for @option{volume} can be
1305 omitted, for example like in:
1311 Increase input audio power by 6 decibels using fixed-point precision:
1313 volume=volume=6dB:precision=fixed
1317 @section volumedetect
1319 Detect the volume of the input video.
1321 The filter has no parameters. The input is not modified. Statistics about
1322 the volume will be printed in the log when the input stream end is reached.
1324 In particular it will show the mean volume (root mean square), maximum
1325 volume (on a per-sample basis), and the beginning of an histogram of the
1326 registered volume values (from the maximum value to a cumulated 1/1000 of
1329 All volumes are in decibels relative to the maximum PCM value.
1331 @subsection Examples
1333 Here is an excerpt of the output:
1335 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1336 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1337 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1338 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1339 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1340 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1341 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1342 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1343 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1349 The mean square energy is approximately -27 dB, or 10^-2.7.
1351 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1353 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1356 In other words, raising the volume by +4 dB does not cause any clipping,
1357 raising it by +5 dB causes clipping for 6 samples, etc.
1359 @c man end AUDIO FILTERS
1361 @chapter Audio Sources
1362 @c man begin AUDIO SOURCES
1364 Below is a description of the currently available audio sources.
1368 Buffer audio frames, and make them available to the filter chain.
1370 This source is mainly intended for a programmatic use, in particular
1371 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1373 It accepts the following mandatory parameters:
1374 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
1379 The sample rate of the incoming audio buffers.
1382 The sample format of the incoming audio buffers.
1383 Either a sample format name or its corresponging integer representation from
1384 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1386 @item channel_layout
1387 The channel layout of the incoming audio buffers.
1388 Either a channel layout name from channel_layout_map in
1389 @file{libavutil/channel_layout.c} or its corresponding integer representation
1390 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1393 The number of channels of the incoming audio buffers.
1394 If both @var{channels} and @var{channel_layout} are specified, then they
1399 @subsection Examples
1402 abuffer=44100:s16p:stereo
1405 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1406 Since the sample format with name "s16p" corresponds to the number
1407 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1415 Generate an audio signal specified by an expression.
1417 This source accepts in input one or more expressions (one for each
1418 channel), which are evaluated and used to generate a corresponding
1421 It accepts the syntax: @var{exprs}[::@var{options}].
1422 @var{exprs} is a list of expressions separated by ":", one for each
1423 separate channel. In case the @var{channel_layout} is not
1424 specified, the selected channel layout depends on the number of
1425 provided expressions.
1427 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1430 The description of the accepted options follows.
1434 @item channel_layout, c
1435 Set the channel layout. The number of channels in the specified layout
1436 must be equal to the number of specified expressions.
1439 Set the minimum duration of the sourced audio. See the function
1440 @code{av_parse_time()} for the accepted format.
1441 Note that the resulting duration may be greater than the specified
1442 duration, as the generated audio is always cut at the end of a
1445 If not specified, or the expressed duration is negative, the audio is
1446 supposed to be generated forever.
1449 Set the number of samples per channel per each output frame,
1452 @item sample_rate, s
1453 Specify the sample rate, default to 44100.
1456 Each expression in @var{exprs} can contain the following constants:
1460 number of the evaluated sample, starting from 0
1463 time of the evaluated sample expressed in seconds, starting from 0
1470 @subsection Examples
1480 Generate a sin signal with frequency of 440 Hz, set sample rate to
1483 aevalsrc="sin(440*2*PI*t)::s=8000"
1487 Generate a two channels signal, specify the channel layout (Front
1488 Center + Back Center) explicitly:
1490 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1494 Generate white noise:
1496 aevalsrc="-2+random(0)"
1500 Generate an amplitude modulated signal:
1502 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1506 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1508 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1515 Null audio source, return unprocessed audio frames. It is mainly useful
1516 as a template and to be employed in analysis / debugging tools, or as
1517 the source for filters which ignore the input data (for example the sox
1520 It accepts an optional sequence of @var{key}=@var{value} pairs,
1523 The description of the accepted options follows.
1527 @item sample_rate, s
1528 Specify the sample rate, and defaults to 44100.
1530 @item channel_layout, cl
1532 Specify the channel layout, and can be either an integer or a string
1533 representing a channel layout. The default value of @var{channel_layout}
1536 Check the channel_layout_map definition in
1537 @file{libavutil/channel_layout.c} for the mapping between strings and
1538 channel layout values.
1541 Set the number of samples per requested frames.
1545 @subsection Examples
1549 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1551 anullsrc=r=48000:cl=4
1555 Do the same operation with a more obvious syntax:
1557 anullsrc=r=48000:cl=mono
1562 Buffer audio frames, and make them available to the filter chain.
1564 This source is not intended to be part of user-supplied graph descriptions but
1565 for insertion by calling programs through the interface defined in
1566 @file{libavfilter/buffersrc.h}.
1568 It accepts the following named parameters:
1572 Timebase which will be used for timestamps of submitted frames. It must be
1573 either a floating-point number or in @var{numerator}/@var{denominator} form.
1579 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1581 @item channel_layout
1582 Channel layout of the audio data, in the form that can be accepted by
1583 @code{av_get_channel_layout()}.
1586 All the parameters need to be explicitly defined.
1590 Synthesize a voice utterance using the libflite library.
1592 To enable compilation of this filter you need to configure FFmpeg with
1593 @code{--enable-libflite}.
1595 Note that the flite library is not thread-safe.
1597 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1600 The description of the accepted parameters follows.
1605 If set to 1, list the names of the available voices and exit
1606 immediately. Default value is 0.
1609 Set the maximum number of samples per frame. Default value is 512.
1612 Set the filename containing the text to speak.
1615 Set the text to speak.
1618 Set the voice to use for the speech synthesis. Default value is
1619 @code{kal}. See also the @var{list_voices} option.
1622 @subsection Examples
1626 Read from file @file{speech.txt}, and synthetize the text using the
1627 standard flite voice:
1629 flite=textfile=speech.txt
1633 Read the specified text selecting the @code{slt} voice:
1635 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1639 Input text to ffmpeg:
1641 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1645 Make @file{ffplay} speak the specified text, using @code{flite} and
1646 the @code{lavfi} device:
1648 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1652 For more information about libflite, check:
1653 @url{http://www.speech.cs.cmu.edu/flite/}
1655 @c man end AUDIO SOURCES
1657 @chapter Audio Sinks
1658 @c man begin AUDIO SINKS
1660 Below is a description of the currently available audio sinks.
1662 @section abuffersink
1664 Buffer audio frames, and make them available to the end of filter chain.
1666 This sink is mainly intended for programmatic use, in particular
1667 through the interface defined in @file{libavfilter/buffersink.h}.
1669 It requires a pointer to an AVABufferSinkContext structure, which
1670 defines the incoming buffers' formats, to be passed as the opaque
1671 parameter to @code{avfilter_init_filter} for initialization.
1675 Null audio sink, do absolutely nothing with the input audio. It is
1676 mainly useful as a template and to be employed in analysis / debugging
1679 @section abuffersink
1680 This sink is intended for programmatic use. Frames that arrive on this sink can
1681 be retrieved by the calling program using the interface defined in
1682 @file{libavfilter/buffersink.h}.
1684 This filter accepts no parameters.
1686 @c man end AUDIO SINKS
1688 @chapter Video Filters
1689 @c man begin VIDEO FILTERS
1691 When you configure your FFmpeg build, you can disable any of the
1692 existing filters using @code{--disable-filters}.
1693 The configure output will show the video filters included in your
1696 Below is a description of the currently available video filters.
1698 @section alphaextract
1700 Extract the alpha component from the input as a grayscale video. This
1701 is especially useful with the @var{alphamerge} filter.
1705 Add or replace the alpha component of the primary input with the
1706 grayscale value of a second input. This is intended for use with
1707 @var{alphaextract} to allow the transmission or storage of frame
1708 sequences that have alpha in a format that doesn't support an alpha
1711 For example, to reconstruct full frames from a normal YUV-encoded video
1712 and a separate video created with @var{alphaextract}, you might use:
1714 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1717 Since this filter is designed for reconstruction, it operates on frame
1718 sequences without considering timestamps, and terminates when either
1719 input reaches end of stream. This will cause problems if your encoding
1720 pipeline drops frames. If you're trying to apply an image as an
1721 overlay to a video stream, consider the @var{overlay} filter instead.
1725 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1726 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1727 Substation Alpha) subtitles files.
1731 Compute the bounding box for the non-black pixels in the input frame
1734 This filter computes the bounding box containing all the pixels with a
1735 luminance value greater than the minimum allowed value.
1736 The parameters describing the bounding box are printed on the filter
1739 @section blackdetect
1741 Detect video intervals that are (almost) completely black. Can be
1742 useful to detect chapter transitions, commercials, or invalid
1743 recordings. Output lines contains the time for the start, end and
1744 duration of the detected black interval expressed in seconds.
1746 In order to display the output lines, you need to set the loglevel at
1747 least to the AV_LOG_INFO value.
1749 This filter accepts a list of options in the form of
1750 @var{key}=@var{value} pairs separated by ":". A description of the
1751 accepted options follows.
1754 @item black_min_duration, d
1755 Set the minimum detected black duration expressed in seconds. It must
1756 be a non-negative floating point number.
1758 Default value is 2.0.
1760 @item picture_black_ratio_th, pic_th
1761 Set the threshold for considering a picture "black".
1762 Express the minimum value for the ratio:
1764 @var{nb_black_pixels} / @var{nb_pixels}
1767 for which a picture is considered black.
1768 Default value is 0.98.
1770 @item pixel_black_th, pix_th
1771 Set the threshold for considering a pixel "black".
1773 The threshold expresses the maximum pixel luminance value for which a
1774 pixel is considered "black". The provided value is scaled according to
1775 the following equation:
1777 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1780 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1781 the input video format, the range is [0-255] for YUV full-range
1782 formats and [16-235] for YUV non full-range formats.
1784 Default value is 0.10.
1787 The following example sets the maximum pixel threshold to the minimum
1788 value, and detects only black intervals of 2 or more seconds:
1790 blackdetect=d=2:pix_th=0.00
1795 Detect frames that are (almost) completely black. Can be useful to
1796 detect chapter transitions or commercials. Output lines consist of
1797 the frame number of the detected frame, the percentage of blackness,
1798 the position in the file if known or -1 and the timestamp in seconds.
1800 In order to display the output lines, you need to set the loglevel at
1801 least to the AV_LOG_INFO value.
1803 The filter accepts the syntax:
1805 blackframe[=@var{amount}:[@var{threshold}]]
1808 @var{amount} is the percentage of the pixels that have to be below the
1809 threshold, and defaults to 98.
1811 @var{threshold} is the threshold below which a pixel value is
1812 considered black, and defaults to 32.
1816 Blend two video frames into each other.
1818 It takes two input streams and outputs one stream, the first input is the
1819 "top" layer and second input is "bottom" layer.
1820 Output terminates when shortest input terminates.
1822 This filter accepts a list of options in the form of @var{key}=@var{value}
1823 pairs separated by ":". A description of the accepted options follows.
1831 Set blend mode for specific pixel component or all pixel components in case
1832 of @var{all_mode}. Default value is @code{normal}.
1834 Available values for component modes are:
1867 Set blend opacity for specific pixel component or all pixel components in case
1868 of @var{all_expr}. Only used in combination with pixel component blend modes.
1875 Set blend expression for specific pixel component or all pixel components in case
1876 of @var{all_expr}. Note that related mode options will be ignored if those are set.
1878 The expressions can use the following variables:
1883 the coordinates of the current sample
1887 the width and height of currently filtered plane
1891 Width and height scale depending on the currently filtered plane. It is the
1892 ratio between the corresponding luma plane number of pixels and the current
1893 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
1894 @code{0.5,0.5} for chroma planes.
1897 Time of the current frame, expressed in seconds.
1900 Value of pixel component at current location for first video frame (top layer).
1903 Value of pixel component at current location for second video frame (bottom layer).
1907 @subsection Examples
1911 Apply transition from bottom layer to top layer in first 10 seconds:
1913 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
1917 Apply 1x1 checkerboard effect:
1919 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
1925 Apply boxblur algorithm to the input video.
1927 The filter accepts parameters as a list of @var{key}=@var{value}
1928 pairs, separated by ":". If the key of the first options is omitted,
1929 the arguments are interpreted according to the syntax
1930 @option{luma_radius}:@option{luma_power}:@option{chroma_radius}:@option{chroma_power}:@option{alpha_radius}:@option{alpha_power}.
1932 A description of the accepted options follows.
1935 @item luma_radius, lr
1936 @item chroma_radius, cr
1937 @item alpha_radius, ar
1938 Set an expression for the box radius in pixels used for blurring the
1939 corresponding input plane.
1941 The radius value must be a non-negative number, and must not be
1942 greater than the value of the expression @code{min(w,h)/2} for the
1943 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
1946 Default value for @option{luma_radius} is "2". If not specified,
1947 @option{chroma_radius} and @option{alpha_radius} default to the
1948 corresponding value set for @option{luma_radius}.
1950 The expressions can contain the following constants:
1953 the input width and height in pixels
1956 the input chroma image width and height in pixels
1959 horizontal and vertical chroma subsample values. For example for the
1960 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1963 @item luma_power, lp
1964 @item chroma_power, cp
1965 @item alpha_power, ap
1966 Specify how many times the boxblur filter is applied to the
1967 corresponding plane.
1969 Default value for @option{luma_power} is 2. If not specified,
1970 @option{chroma_power} and @option{alpha_power} default to the
1971 corresponding value set for @option{luma_power}.
1973 A value of 0 will disable the effect.
1976 @subsection Examples
1980 Apply a boxblur filter with luma, chroma, and alpha radius
1987 Set luma radius to 2, alpha and chroma radius to 0:
1989 boxblur=2:1:cr=0:ar=0
1993 Set luma and chroma radius to a fraction of the video dimension:
1995 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
1999 @section colormatrix
2001 The colormatrix filter allows conversion between any of the following color
2002 space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m})
2003 and FCC (@var{fcc}).
2005 The syntax of the parameters is @var{source}:@var{destination}:
2008 colormatrix=bt601:smpte240m
2013 Copy the input source unchanged to the output. Mainly useful for
2018 Crop the input video.
2020 This filter accepts a list of @var{key}=@var{value} pairs as argument,
2021 separated by ':'. If the key of the first options is omitted, the
2022 arguments are interpreted according to the syntax
2023 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
2025 A description of the accepted options follows:
2028 Set the crop area width. It defaults to @code{iw}.
2029 This expression is evaluated only once during the filter
2033 Set the crop area width. It defaults to @code{ih}.
2034 This expression is evaluated only once during the filter
2038 Set the expression for the x top-left coordinate of the cropped area.
2039 It defaults to @code{(in_w-out_w)/2}.
2040 This expression is evaluated per-frame.
2043 Set the expression for the y top-left coordinate of the cropped area.
2044 It defaults to @code{(in_h-out_h)/2}.
2045 This expression is evaluated per-frame.
2048 If set to 1 will force the output display aspect ratio
2049 to be the same of the input, by changing the output sample aspect
2050 ratio. It defaults to 0.
2053 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2054 expressions containing the following constants:
2058 the computed values for @var{x} and @var{y}. They are evaluated for
2062 the input width and height
2065 same as @var{in_w} and @var{in_h}
2068 the output (cropped) width and height
2071 same as @var{out_w} and @var{out_h}
2074 same as @var{iw} / @var{ih}
2077 input sample aspect ratio
2080 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2083 horizontal and vertical chroma subsample values. For example for the
2084 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2087 the number of input frame, starting from 0
2090 the position in the file of the input frame, NAN if unknown
2093 timestamp expressed in seconds, NAN if the input timestamp is unknown
2097 The expression for @var{out_w} may depend on the value of @var{out_h},
2098 and the expression for @var{out_h} may depend on @var{out_w}, but they
2099 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2100 evaluated after @var{out_w} and @var{out_h}.
2102 The @var{x} and @var{y} parameters specify the expressions for the
2103 position of the top-left corner of the output (non-cropped) area. They
2104 are evaluated for each frame. If the evaluated value is not valid, it
2105 is approximated to the nearest valid value.
2107 The expression for @var{x} may depend on @var{y}, and the expression
2108 for @var{y} may depend on @var{x}.
2110 @subsection Examples
2114 Crop area with size 100x100 at position (12,34).
2119 Using named options, the example above becomes:
2121 crop=w=100:h=100:x=12:y=34
2125 Crop the central input area with size 100x100:
2131 Crop the central input area with size 2/3 of the input video:
2133 crop=2/3*in_w:2/3*in_h
2137 Crop the input video central square:
2143 Delimit the rectangle with the top-left corner placed at position
2144 100:100 and the right-bottom corner corresponding to the right-bottom
2145 corner of the input image:
2147 crop=in_w-100:in_h-100:100:100
2151 Crop 10 pixels from the left and right borders, and 20 pixels from
2152 the top and bottom borders
2154 crop=in_w-2*10:in_h-2*20
2158 Keep only the bottom right quarter of the input image:
2160 crop=in_w/2:in_h/2:in_w/2:in_h/2
2164 Crop height for getting Greek harmony:
2166 crop=in_w:1/PHI*in_w
2170 Appply trembling effect:
2172 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)
2176 Apply erratic camera effect depending on timestamp:
2178 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)"
2182 Set x depending on the value of y:
2184 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2190 Auto-detect crop size.
2192 Calculate necessary cropping parameters and prints the recommended
2193 parameters through the logging system. The detected dimensions
2194 correspond to the non-black area of the input video.
2196 It accepts the syntax:
2198 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
2204 Threshold, which can be optionally specified from nothing (0) to
2205 everything (255), defaults to 24.
2208 Value which the width/height should be divisible by, defaults to
2209 16. The offset is automatically adjusted to center the video. Use 2 to
2210 get only even dimensions (needed for 4:2:2 video). 16 is best when
2211 encoding to most video codecs.
2214 Counter that determines after how many frames cropdetect will reset
2215 the previously detected largest video area and start over to detect
2216 the current optimal crop area. Defaults to 0.
2218 This can be useful when channel logos distort the video area. 0
2219 indicates never reset and return the largest area encountered during
2225 Drop frames that do not differ greatly from the previous frame in
2226 order to reduce framerate.
2228 The main use of this filter is for very-low-bitrate encoding
2229 (e.g. streaming over dialup modem), but it could in theory be used for
2230 fixing movies that were inverse-telecined incorrectly.
2232 The filter accepts parameters as a list of @var{key}=@var{value}
2233 pairs, separated by ":". If the key of the first options is omitted,
2234 the arguments are interpreted according to the syntax:
2235 @option{max}:@option{hi}:@option{lo}:@option{frac}.
2237 A description of the accepted options follows.
2241 Set the maximum number of consecutive frames which can be dropped (if
2242 positive), or the minimum interval between dropped frames (if
2243 negative). If the value is 0, the frame is dropped unregarding the
2244 number of previous sequentially dropped frames.
2251 Set the dropping threshold values.
2253 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
2254 represent actual pixel value differences, so a threshold of 64
2255 corresponds to 1 unit of difference for each pixel, or the same spread
2256 out differently over the block.
2258 A frame is a candidate for dropping if no 8x8 blocks differ by more
2259 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
2260 meaning the whole image) differ by more than a threshold of @option{lo}.
2262 Default value for @option{hi} is 64*12, default value for @option{lo} is
2263 64*5, and default value for @option{frac} is 0.33.
2268 Suppress a TV station logo by a simple interpolation of the surrounding
2269 pixels. Just set a rectangle covering the logo and watch it disappear
2270 (and sometimes something even uglier appear - your mileage may vary).
2272 The filter accepts parameters as a string of the form
2273 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
2274 @var{key}=@var{value} pairs, separated by ":".
2276 The description of the accepted parameters follows.
2281 Specify the top left corner coordinates of the logo. They must be
2285 Specify the width and height of the logo to clear. They must be
2289 Specify the thickness of the fuzzy edge of the rectangle (added to
2290 @var{w} and @var{h}). The default value is 4.
2293 When set to 1, a green rectangle is drawn on the screen to simplify
2294 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2295 @var{band} is set to 4. The default value is 0.
2299 @subsection Examples
2303 Set a rectangle covering the area with top left corner coordinates 0,0
2304 and size 100x77, setting a band of size 10:
2306 delogo=0:0:100:77:10
2310 As the previous example, but use named options:
2312 delogo=x=0:y=0:w=100:h=77:band=10
2319 Attempt to fix small changes in horizontal and/or vertical shift. This
2320 filter helps remove camera shake from hand-holding a camera, bumping a
2321 tripod, moving on a vehicle, etc.
2323 The filter accepts parameters as a list of @var{key}=@var{value}
2324 pairs, separated by ":". If the key of the first options is omitted,
2325 the arguments are interpreted according to the syntax
2326 @var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}.
2328 A description of the accepted parameters follows.
2333 Specify a rectangular area where to limit the search for motion
2335 If desired the search for motion vectors can be limited to a
2336 rectangular area of the frame defined by its top left corner, width
2337 and height. These parameters have the same meaning as the drawbox
2338 filter which can be used to visualise the position of the bounding
2341 This is useful when simultaneous movement of subjects within the frame
2342 might be confused for camera motion by the motion vector search.
2344 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2345 then the full frame is used. This allows later options to be set
2346 without specifying the bounding box for the motion vector search.
2348 Default - search the whole frame.
2351 Specify the maximum extent of movement in x and y directions in the
2352 range 0-64 pixels. Default 16.
2355 Specify how to generate pixels to fill blanks at the edge of the
2356 frame. Available values are:
2359 Fill zeroes at blank locations
2361 Original image at blank locations
2363 Extruded edge value at blank locations
2365 Mirrored edge at blank locations
2367 Default value is @samp{mirror}.
2370 Specify the blocksize to use for motion search. Range 4-128 pixels,
2374 Specify the contrast threshold for blocks. Only blocks with more than
2375 the specified contrast (difference between darkest and lightest
2376 pixels) will be considered. Range 1-255, default 125.
2379 Specify the search strategy. Available values are:
2382 Set exhaustive search
2384 Set less exhaustive search.
2386 Default value is @samp{exhaustive}.
2389 If set then a detailed log of the motion search is written to the
2396 Draw a colored box on the input image.
2398 The filter accepts parameters as a list of @var{key}=@var{value}
2399 pairs, separated by ":". If the key of the first options is omitted,
2400 the arguments are interpreted according to the syntax
2401 @option{x}:@option{y}:@option{width}:@option{height}:@option{color}:@option{thickness}.
2403 A description of the accepted options follows.
2407 Specify the top left corner coordinates of the box. Default to 0.
2411 Specify the width and height of the box, if 0 they are interpreted as
2412 the input width and height. Default to 0.
2415 Specify the color of the box to write, it can be the name of a color
2416 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2417 value @code{invert} is used, the box edge color is the same as the
2418 video with inverted luma.
2421 Set the thickness of the box edge. Default value is @code{4}.
2424 @subsection Examples
2428 Draw a black box around the edge of the input image:
2434 Draw a box with color red and an opacity of 50%:
2436 drawbox=10:20:200:60:red@@0.5
2439 The previous example can be specified as:
2441 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2445 Fill the box with pink color:
2447 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2454 Draw text string or text from specified file on top of video using the
2455 libfreetype library.
2457 To enable compilation of this filter you need to configure FFmpeg with
2458 @code{--enable-libfreetype}.
2462 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
2465 The description of the accepted parameters follows.
2470 Used to draw a box around text using background color.
2471 Value should be either 1 (enable) or 0 (disable).
2472 The default value of @var{box} is 0.
2475 The color to be used for drawing box around text.
2476 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2477 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2478 The default value of @var{boxcolor} is "white".
2481 Set an expression which specifies if the text should be drawn. If the
2482 expression evaluates to 0, the text is not drawn. This is useful for
2483 specifying that the text should be drawn only when specific conditions
2486 Default value is "1".
2488 See below for the list of accepted constants and functions.
2491 Select how the @var{text} is expanded. Can be either @code{none},
2492 @code{strftime} (deprecated) or
2493 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2497 If true, check and fix text coords to avoid clipping.
2500 The color to be used for drawing fonts.
2501 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2502 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2503 The default value of @var{fontcolor} is "black".
2506 The font file to be used for drawing text. Path must be included.
2507 This parameter is mandatory.
2510 The font size to be used for drawing text.
2511 The default value of @var{fontsize} is 16.
2514 Flags to be used for loading the fonts.
2516 The flags map the corresponding flags supported by libfreetype, and are
2517 a combination of the following values:
2524 @item vertical_layout
2525 @item force_autohint
2528 @item ignore_global_advance_width
2530 @item ignore_transform
2537 Default value is "render".
2539 For more information consult the documentation for the FT_LOAD_*
2543 The color to be used for drawing a shadow behind the drawn text. It
2544 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2545 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2546 The default value of @var{shadowcolor} is "black".
2548 @item shadowx, shadowy
2549 The x and y offsets for the text shadow position with respect to the
2550 position of the text. They can be either positive or negative
2551 values. Default value for both is "0".
2554 The size in number of spaces to use for rendering the tab.
2558 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2559 format. It can be used with or without text parameter. @var{timecode_rate}
2560 option must be specified.
2562 @item timecode_rate, rate, r
2563 Set the timecode frame rate (timecode only).
2566 The text string to be drawn. The text must be a sequence of UTF-8
2568 This parameter is mandatory if no file is specified with the parameter
2572 A text file containing text to be drawn. The text must be a sequence
2573 of UTF-8 encoded characters.
2575 This parameter is mandatory if no text string is specified with the
2576 parameter @var{text}.
2578 If both @var{text} and @var{textfile} are specified, an error is thrown.
2581 If set to 1, the @var{textfile} will be reloaded before each frame.
2582 Be sure to update it atomically, or it may be read partially, or even fail.
2585 The expressions which specify the offsets where text will be drawn
2586 within the video frame. They are relative to the top/left border of the
2589 The default value of @var{x} and @var{y} is "0".
2591 See below for the list of accepted constants and functions.
2594 The parameters for @var{x} and @var{y} are expressions containing the
2595 following constants and functions:
2599 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2602 horizontal and vertical chroma subsample values. For example for the
2603 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2606 the height of each text line
2614 @item max_glyph_a, ascent
2615 the maximum distance from the baseline to the highest/upper grid
2616 coordinate used to place a glyph outline point, for all the rendered
2618 It is a positive value, due to the grid's orientation with the Y axis
2621 @item max_glyph_d, descent
2622 the maximum distance from the baseline to the lowest grid coordinate
2623 used to place a glyph outline point, for all the rendered glyphs.
2624 This is a negative value, due to the grid's orientation, with the Y axis
2628 maximum glyph height, that is the maximum height for all the glyphs
2629 contained in the rendered text, it is equivalent to @var{ascent} -
2633 maximum glyph width, that is the maximum width for all the glyphs
2634 contained in the rendered text
2637 the number of input frame, starting from 0
2639 @item rand(min, max)
2640 return a random number included between @var{min} and @var{max}
2643 input sample aspect ratio
2646 timestamp expressed in seconds, NAN if the input timestamp is unknown
2649 the height of the rendered text
2652 the width of the rendered text
2655 the x and y offset coordinates where the text is drawn.
2657 These parameters allow the @var{x} and @var{y} expressions to refer
2658 each other, so you can for example specify @code{y=x/dar}.
2661 If libavfilter was built with @code{--enable-fontconfig}, then
2662 @option{fontfile} can be a fontconfig pattern or omitted.
2664 @anchor{drawtext_expansion}
2665 @subsection Text expansion
2667 If @option{expansion} is set to @code{strftime},
2668 the filter recognizes strftime() sequences in the provided text and
2669 expands them accordingly. Check the documentation of strftime(). This
2670 feature is deprecated.
2672 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2674 If @option{expansion} is set to @code{normal} (which is the default),
2675 the following expansion mechanism is used.
2677 The backslash character '\', followed by any character, always expands to
2678 the second character.
2680 Sequence of the form @code{%@{...@}} are expanded. The text between the
2681 braces is a function name, possibly followed by arguments separated by ':'.
2682 If the arguments contain special characters or delimiters (':' or '@}'),
2683 they should be escaped.
2685 Note that they probably must also be escaped as the value for the
2686 @option{text} option in the filter argument string and as the filter
2687 argument in the filter graph description, and possibly also for the shell,
2688 that makes up to four levels of escaping; using a text file avoids these
2691 The following functions are available:
2696 The expression evaluation result.
2698 It must take one argument specifying the expression to be evaluated,
2699 which accepts the same constants and functions as the @var{x} and
2700 @var{y} values. Note that not all constants should be used, for
2701 example the text size is not known when evaluating the expression, so
2702 the constants @var{text_w} and @var{text_h} will have an undefined
2706 The time at which the filter is running, expressed in UTC.
2707 It can accept an argument: a strftime() format string.
2710 The time at which the filter is running, expressed in the local time zone.
2711 It can accept an argument: a strftime() format string.
2714 The frame number, starting from 0.
2717 The timestamp of the current frame, in seconds, with microsecond accuracy.
2721 @subsection Examples
2725 Draw "Test Text" with font FreeSerif, using the default values for the
2726 optional parameters.
2729 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2733 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2734 and y=50 (counting from the top-left corner of the screen), text is
2735 yellow with a red box around it. Both the text and the box have an
2739 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2740 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2743 Note that the double quotes are not necessary if spaces are not used
2744 within the parameter list.
2747 Show the text at the center of the video frame:
2749 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2753 Show a text line sliding from right to left in the last row of the video
2754 frame. The file @file{LONG_LINE} is assumed to contain a single line
2757 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2761 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2763 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2767 Draw a single green letter "g", at the center of the input video.
2768 The glyph baseline is placed at half screen height.
2770 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2774 Show text for 1 second every 3 seconds:
2776 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2780 Use fontconfig to set the font. Note that the colons need to be escaped.
2782 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2786 Print the date of a real-time encoding (see strftime(3)):
2788 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
2793 For more information about libfreetype, check:
2794 @url{http://www.freetype.org/}.
2796 For more information about fontconfig, check:
2797 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
2801 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
2803 This filter accepts the following optional named parameters:
2807 Set low and high threshold values used by the Canny thresholding
2810 The high threshold selects the "strong" edge pixels, which are then
2811 connected through 8-connectivity with the "weak" edge pixels selected
2812 by the low threshold.
2814 @var{low} and @var{high} threshold values must be choosen in the range
2815 [0,1], and @var{low} should be lesser or equal to @var{high}.
2817 Default value for @var{low} is @code{20/255}, and default value for @var{high}
2823 edgedetect=low=0.1:high=0.4
2828 Apply fade-in/out effect to input video.
2830 The filter accepts parameters as a list of @var{key}=@var{value}
2831 pairs, separated by ":". If the key of the first options is omitted,
2832 the arguments are interpreted according to the syntax
2833 @var{type}:@var{start_frame}:@var{nb_frames}.
2835 A description of the accepted parameters follows.
2839 Specify if the effect type, can be either @code{in} for fade-in, or
2840 @code{out} for a fade-out effect. Default is @code{in}.
2842 @item start_frame, s
2843 Specify the number of the start frame for starting to apply the fade
2844 effect. Default is 0.
2847 Specify the number of frames for which the fade effect has to last. At
2848 the end of the fade-in effect the output video will have the same
2849 intensity as the input video, at the end of the fade-out transition
2850 the output video will be completely black. Default is 25.
2853 If set to 1, fade only alpha channel, if one exists on the input.
2857 @subsection Examples
2861 Fade in first 30 frames of video:
2866 The command above is equivalent to:
2872 Fade out last 45 frames of a 200-frame video:
2878 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
2880 fade=in:0:25, fade=out:975:25
2884 Make first 5 frames black, then fade in from frame 5-24:
2890 Fade in alpha over first 25 frames of video:
2892 fade=in:0:25:alpha=1
2898 Extract a single field from an interlaced image using stride
2899 arithmetic to avoid wasting CPU time. The output frames are marked as
2902 This filter accepts the following named options:
2905 Specify whether to extract the top (if the value is @code{0} or
2906 @code{top}) or the bottom field (if the value is @code{1} or
2910 If the option key is not specified, the first value sets the @var{type}
2911 option. For example:
2923 Transform the field order of the input video.
2925 It accepts one parameter which specifies the required field order that
2926 the input interlaced video will be transformed to. The parameter can
2927 assume one of the following values:
2931 output bottom field first
2933 output top field first
2936 Default value is "tff".
2938 Transformation is achieved by shifting the picture content up or down
2939 by one line, and filling the remaining line with appropriate picture content.
2940 This method is consistent with most broadcast field order converters.
2942 If the input video is not flagged as being interlaced, or it is already
2943 flagged as being of the required output field order then this filter does
2944 not alter the incoming video.
2946 This filter is very useful when converting to or from PAL DV material,
2947 which is bottom field first.
2951 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
2956 Buffer input images and send them when they are requested.
2958 This filter is mainly useful when auto-inserted by the libavfilter
2961 The filter does not take parameters.
2965 Convert the input video to one of the specified pixel formats.
2966 Libavfilter will try to pick one that is supported for the input to
2969 The filter accepts a list of pixel format names, separated by ":",
2970 for example "yuv420p:monow:rgb24".
2972 @subsection Examples
2976 Convert the input video to the format @var{yuv420p}
2981 Convert the input video to any of the formats in the list
2983 format=yuv420p:yuv444p:yuv410p
2989 Convert the video to specified constant framerate by duplicating or dropping
2990 frames as necessary.
2992 This filter accepts the following named parameters:
2996 Desired output framerate. The default is @code{25}.
3001 Possible values are:
3004 zero round towards 0
3008 round towards -infinity
3010 round towards +infinity
3014 The default is @code{near}.
3018 Alternatively, the options can be specified as a flat string:
3019 @var{fps}[:@var{round}].
3021 See also the @ref{setpts} filter.
3025 Select one frame every N.
3027 This filter accepts in input a string representing a positive
3028 integer. Default argument is @code{1}.
3033 Apply a frei0r effect to the input video.
3035 To enable compilation of this filter you need to install the frei0r
3036 header and configure FFmpeg with @code{--enable-frei0r}.
3038 The filter supports the syntax:
3040 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
3043 @var{filter_name} is the name of the frei0r effect to load. If the
3044 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
3045 is searched in each one of the directories specified by the colon (or
3046 semicolon on Windows platforms) separated list in @env{FREIOR_PATH},
3047 otherwise in the standard frei0r paths, which are in this order:
3048 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3049 @file{/usr/lib/frei0r-1/}.
3051 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
3052 for the frei0r effect.
3054 A frei0r effect parameter can be a boolean (whose values are specified
3055 with "y" and "n"), a double, a color (specified by the syntax
3056 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3057 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3058 description), a position (specified by the syntax @var{X}/@var{Y},
3059 @var{X} and @var{Y} being float numbers) and a string.
3061 The number and kind of parameters depend on the loaded effect. If an
3062 effect parameter is not specified the default value is set.
3064 @subsection Examples
3068 Apply the distort0r effect, set the first two double parameters:
3070 frei0r=distort0r:0.5:0.01
3074 Apply the colordistance effect, take a color as first parameter:
3076 frei0r=colordistance:0.2/0.3/0.4
3077 frei0r=colordistance:violet
3078 frei0r=colordistance:0x112233
3082 Apply the perspective effect, specify the top left and top right image
3085 frei0r=perspective:0.2/0.2:0.8/0.2
3089 For more information see:
3090 @url{http://frei0r.dyne.org}
3094 The filter takes one, two, three or four equations as parameter, separated by ':'.
3095 The first equation is mandatory and applies to the luma plane. The two
3096 following are respectively for chroma blue and chroma red planes.
3098 The filter syntax allows named parameters:
3102 the luminance expression
3104 the chrominance blue expression
3106 the chrominance red expression
3108 the alpha expression
3111 If one of the chrominance expression is not defined, it falls back on the other
3112 one. If no alpha expression is specified it will evaluate to opaque value.
3113 If none of chrominance expressions are
3114 specified, they will evaluate the luminance expression.
3116 The expressions can use the following variables and functions:
3120 The sequential number of the filtered frame, starting from @code{0}.
3123 The coordinates of the current sample.
3126 The width and height of the image.
3129 Width and height scale depending on the currently filtered plane. It is the
3130 ratio between the corresponding luma plane number of pixels and the current
3131 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3132 @code{0.5,0.5} for chroma planes.
3135 Time of the current frame, expressed in seconds.
3138 Return the value of the pixel at location (@var{x},@var{y}) of the current
3142 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3146 Return the value of the pixel at location (@var{x},@var{y}) of the
3147 blue-difference chroma plane. Returns 0 if there is no such plane.
3150 Return the value of the pixel at location (@var{x},@var{y}) of the
3151 red-difference chroma plane. Returns 0 if there is no such plane.
3154 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
3155 plane. Returns 0 if there is no such plane.
3158 For functions, if @var{x} and @var{y} are outside the area, the value will be
3159 automatically clipped to the closer edge.
3161 @subsection Examples
3165 Flip the image horizontally:
3171 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3172 wavelength of 100 pixels:
3174 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3178 Generate a fancy enigmatic moving light:
3180 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
3186 Fix the banding artifacts that are sometimes introduced into nearly flat
3187 regions by truncation to 8bit color depth.
3188 Interpolate the gradients that should go where the bands are, and
3191 This filter is designed for playback only. Do not use it prior to
3192 lossy compression, because compression tends to lose the dither and
3193 bring back the bands.
3195 The filter accepts a list of options in the form of @var{key}=@var{value} pairs
3196 separated by ":". A description of the accepted options follows.
3201 The maximum amount by which the filter will change
3202 any one pixel. Also the threshold for detecting nearly flat
3203 regions. Acceptable values range from @code{0.51} to @code{64}, default value
3207 The neighborhood to fit the gradient to. A larger
3208 radius makes for smoother gradients, but also prevents the filter from
3209 modifying the pixels near detailed regions. Acceptable values are
3210 @code{8-32}, default value is @code{16}.
3214 Alternatively, the options can be specified as a flat string:
3215 @var{strength}[:@var{radius}]
3217 @subsection Examples
3221 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3227 Specify radius, omitting the strength (which will fall-back to the default
3237 Flip the input video horizontally.
3239 For example to horizontally flip the input video with @command{ffmpeg}:
3241 ffmpeg -i in.avi -vf "hflip" out.avi
3245 This filter applies a global color histogram equalization on a
3248 It can be used to correct video that has a compressed range of pixel
3249 intensities. The filter redistributes the pixel intensities to
3250 equalize their distribution across the intensity range. It may be
3251 viewed as an "automatically adjusting contrast filter". This filter is
3252 useful only for correcting degraded or poorly captured source
3255 The filter accepts parameters as a list of @var{key}=@var{value}
3256 pairs, separated by ":". If the key of the first options is omitted,
3257 the arguments are interpreted according to syntax
3258 @var{strength}:@var{intensity}:@var{antibanding}.
3260 This filter accepts the following named options:
3264 Determine the amount of equalization to be applied. As the strength
3265 is reduced, the distribution of pixel intensities more-and-more
3266 approaches that of the input frame. The value must be a float number
3267 in the range [0,1] and defaults to 0.200.
3270 Set the maximum intensity that can generated and scale the output
3271 values appropriately. The strength should be set as desired and then
3272 the intensity can be limited if needed to avoid washing-out. The value
3273 must be a float number in the range [0,1] and defaults to 0.210.
3276 Set the antibanding level. If enabled the filter will randomly vary
3277 the luminance of output pixels by a small amount to avoid banding of
3278 the histogram. Possible values are @code{none}, @code{weak} or
3279 @code{strong}. It defaults to @code{none}.
3284 Compute and draw a color distribution histogram for the input video.
3286 The computed histogram is a representation of distribution of color components
3289 The filter accepts the following named parameters:
3295 It accepts the following values:
3298 standard histogram that display color components distribution in an image.
3299 Displays color graph for each color component. Shows distribution
3300 of the Y, U, V, A or G, B, R components, depending on input format,
3301 in current frame. Bellow each graph is color component scale meter.
3304 chroma values in vectorscope, if brighter more such chroma values are
3305 distributed in an image.
3306 Displays chroma values (U/V color placement) in two dimensional graph
3307 (which is called a vectorscope). It can be used to read of the hue and
3308 saturation of the current frame. At a same time it is a histogram.
3309 The whiter a pixel in the vectorscope, the more pixels of the input frame
3310 correspond to that pixel (that is the more pixels have this chroma value).
3311 The V component is displayed on the horizontal (X) axis, with the leftmost
3312 side being V = 0 and the rightmost side being V = 255.
3313 The U component is displayed on the vertical (Y) axis, with the top
3314 representing U = 0 and the bottom representing U = 255.
3316 The position of a white pixel in the graph corresponds to the chroma value
3317 of a pixel of the input clip. So the graph can be used to read of the
3318 hue (color flavor) and the saturation (the dominance of the hue in the color).
3319 As the hue of a color changes, it moves around the square. At the center of
3320 the square, the saturation is zero, which means that the corresponding pixel
3321 has no color. If you increase the amount of a specific color, while leaving
3322 the other colors unchanged, the saturation increases, and you move towards
3323 the edge of the square.
3326 chroma values in vectorscope, similar as @code{color} but actual chroma values
3330 per row/column color component graph. In row mode graph in the left side represents
3331 color component value 0 and right side represents value = 255. In column mode top
3332 side represents color component value = 0 and bottom side represents value = 255.
3334 Default value is @code{levels}.
3337 Set height of level in @code{levels}. Default value is @code{200}.
3338 Allowed range is [50, 2048].
3341 Set height of color scale in @code{levels}. Default value is @code{12}.
3342 Allowed range is [0, 40].
3345 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3346 of same luminance values across input rows/columns are distributed.
3347 Default value is @code{10}. Allowed range is [1, 255].
3350 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3351 Default is @code{row}.
3354 Set display mode for @code{waveform} and @code{levels}.
3355 It accepts the following values:
3358 Display separate graph for the color components side by side in
3359 @code{row} waveform mode or one below other in @code{column} waveform mode
3360 for @code{waveform} histogram mode. For @code{levels} histogram mode
3361 per color component graphs are placed one bellow other.
3363 This display mode in @code{waveform} histogram mode makes it easy to spot
3364 color casts in the highlights and shadows of an image, by comparing the
3365 contours of the top and the bottom of each waveform.
3366 Since whites, grays, and blacks are characterized by
3367 exactly equal amounts of red, green, and blue, neutral areas of the
3368 picture should display three waveforms of roughly equal width/height.
3369 If not, the correction is easy to make by making adjustments to level the
3373 Presents information that's identical to that in the @code{parade}, except
3374 that the graphs representing color components are superimposed directly
3377 This display mode in @code{waveform} histogram mode can make it easier to spot
3378 the relative differences or similarities in overlapping areas of the color
3379 components that are supposed to be identical, such as neutral whites, grays,
3382 Default is @code{parade}.
3385 @subsection Examples
3390 Calculate and draw histogram:
3392 ffplay -i input -vf histogram
3399 High precision/quality 3d denoise filter. This filter aims to reduce
3400 image noise producing smooth images and making still images really
3401 still. It should enhance compressibility.
3403 It accepts the following optional parameters:
3404 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
3408 a non-negative float number which specifies spatial luma strength,
3411 @item chroma_spatial
3412 a non-negative float number which specifies spatial chroma strength,
3413 defaults to 3.0*@var{luma_spatial}/4.0
3416 a float number which specifies luma temporal strength, defaults to
3417 6.0*@var{luma_spatial}/4.0
3420 a float number which specifies chroma temporal strength, defaults to
3421 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3426 Modify the hue and/or the saturation of the input.
3428 This filter accepts the following optional named options:
3432 Specify the hue angle as a number of degrees. It accepts a float
3433 number or an expression, and defaults to 0.0.
3436 Specify the hue angle as a number of radians. It accepts a float
3437 number or an expression, and defaults to 0.0.
3440 Specify the saturation in the [-10,10] range. It accepts a float number and
3444 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3445 following constants:
3449 frame count of the input frame starting from 0
3452 presentation timestamp of the input frame expressed in time base units
3455 frame rate of the input video, NAN if the input frame rate is unknown
3458 timestamp expressed in seconds, NAN if the input timestamp is unknown
3461 time base of the input video
3464 The options can also be set using the syntax: @var{hue}:@var{saturation}
3466 In this case @var{hue} is expressed in degrees.
3468 @subsection Examples
3472 Set the hue to 90 degrees and the saturation to 1.0:
3478 Same command but expressing the hue in radians:
3484 Same command without named options, hue must be expressed in degrees:
3490 Note that "h:s" syntax does not support expressions for the values of
3491 h and s, so the following example will issue an error:
3497 Rotate hue and make the saturation swing between 0
3498 and 2 over a period of 1 second:
3500 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3504 Apply a 3 seconds saturation fade-in effect starting at 0:
3509 The general fade-in expression can be written as:
3511 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3515 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3517 hue="s=max(0\, min(1\, (8-t)/3))"
3520 The general fade-out expression can be written as:
3522 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3527 @subsection Commands
3529 This filter supports the following command:
3532 Modify the hue and/or the saturation of the input video.
3533 The command accepts the same named options and syntax than when calling the
3534 filter from the command-line.
3536 If a parameter is omitted, it is kept at its current value.
3541 Detect video interlacing type.
3543 This filter tries to detect if the input is interlaced or progressive,
3544 top or bottom field first.
3548 Deinterleave or interleave fields.
3550 This filter allows to process interlaced images fields without
3551 deinterlacing them. Deinterleaving splits the input frame into 2
3552 fields (so called half pictures). Odd lines are moved to the top
3553 half of the output image, even lines to the bottom half.
3554 You can process (filter) them independently and then re-interleave them.
3556 It accepts a list of options in the form of @var{key}=@var{value} pairs
3557 separated by ":". A description of the accepted options follows.
3561 @item chroma_mode, s
3563 Available values for @var{luma_mode}, @var{chroma_mode} and
3564 @var{alpha_mode} are:
3570 @item deinterleave, d
3571 Deinterleave fields, placing one above the other.
3574 Interleave fields. Reverse the effect of deinterleaving.
3576 Default value is @code{none}.
3579 @item chroma_swap, cs
3580 @item alpha_swap, as
3581 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3586 Deinterlace input video by applying Donald Graft's adaptive kernel
3587 deinterling. Work on interlaced parts of a video to produce
3590 This filter accepts parameters as a list of @var{key}=@var{value}
3591 pairs, separated by ":". If the key of the first options is omitted,
3592 the arguments are interpreted according to the following syntax:
3593 @var{thresh}:@var{map}:@var{order}:@var{sharp}:@var{twoway}.
3595 The description of the accepted parameters follows.
3599 Set the threshold which affects the filter's tolerance when
3600 determining if a pixel line must be processed. It must be an integer
3601 in the range [0,255] and defaults to 10. A value of 0 will result in
3602 applying the process on every pixels.
3605 Paint pixels exceeding the threshold value to white if set to 1.
3609 Set the fields order. Swap fields if set to 1, leave fields alone if
3613 Enable additional sharpening if set to 1. Default is 0.
3616 Enable twoway sharpening if set to 1. Default is 0.
3619 @subsection Examples
3623 Apply default values:
3625 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3629 Enable additional sharpening:
3635 Paint processed pixels in white:
3641 @section lut, lutrgb, lutyuv
3643 Compute a look-up table for binding each pixel component input value
3644 to an output value, and apply it to input video.
3646 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3647 to an RGB input video.
3649 These filters accept in input a ":"-separated list of options, which
3650 specify the expressions used for computing the lookup table for the
3651 corresponding pixel component values.
3653 The @var{lut} filter requires either YUV or RGB pixel formats in
3654 input, and accepts the options:
3657 set first pixel component expression
3659 set second pixel component expression
3661 set third pixel component expression
3663 set fourth pixel component expression, corresponds to the alpha component
3666 The exact component associated to each option depends on the format in
3669 The @var{lutrgb} filter requires RGB pixel formats in input, and
3670 accepts the options:
3673 set red component expression
3675 set green component expression
3677 set blue component expression
3679 alpha component expression
3682 The @var{lutyuv} filter requires YUV pixel formats in input, and
3683 accepts the options:
3686 set Y/luminance component expression
3688 set U/Cb component expression
3690 set V/Cr component expression
3692 set alpha component expression
3695 The expressions can contain the following constants and functions:
3699 the input width and height
3702 input value for the pixel component
3705 the input value clipped in the @var{minval}-@var{maxval} range
3708 maximum value for the pixel component
3711 minimum value for the pixel component
3714 the negated value for the pixel component value clipped in the
3715 @var{minval}-@var{maxval} range , it corresponds to the expression
3716 "maxval-clipval+minval"
3719 the computed value in @var{val} clipped in the
3720 @var{minval}-@var{maxval} range
3722 @item gammaval(gamma)
3723 the computed gamma correction value of the pixel component value
3724 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3726 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3730 All expressions default to "val".
3732 @subsection Examples
3738 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3739 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3742 The above is the same as:
3744 lutrgb="r=negval:g=negval:b=negval"
3745 lutyuv="y=negval:u=negval:v=negval"
3755 Remove chroma components, turns the video into a graytone image:
3757 lutyuv="u=128:v=128"
3761 Apply a luma burning effect:
3767 Remove green and blue components:
3773 Set a constant alpha channel value on input:
3775 format=rgba,lutrgb=a="maxval-minval/2"
3779 Correct luminance gamma by a 0.5 factor:
3781 lutyuv=y=gammaval(0.5)
3787 Apply an MPlayer filter to the input video.
3789 This filter provides a wrapper around most of the filters of
3792 This wrapper is considered experimental. Some of the wrapped filters
3793 may not work properly and we may drop support for them, as they will
3794 be implemented natively into FFmpeg. Thus you should avoid
3795 depending on them when writing portable scripts.
3797 The filters accepts the parameters:
3798 @var{filter_name}[:=]@var{filter_params}
3800 @var{filter_name} is the name of a supported MPlayer filter,
3801 @var{filter_params} is a string containing the parameters accepted by
3804 The list of the currently supported filters follows:
3832 The parameter syntax and behavior for the listed filters are the same
3833 of the corresponding MPlayer filters. For detailed instructions check
3834 the "VIDEO FILTERS" section in the MPlayer manual.
3836 @subsection Examples
3840 Adjust gamma, brightness, contrast:
3846 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
3852 This filter accepts an integer in input, if non-zero it negates the
3853 alpha component (if available). The default value in input is 0.
3857 Force libavfilter not to use any of the specified pixel formats for the
3858 input to the next filter.
3860 The filter accepts a list of pixel format names, separated by ":",
3861 for example "yuv420p:monow:rgb24".
3863 @subsection Examples
3867 Force libavfilter to use a format different from @var{yuv420p} for the
3868 input to the vflip filter:
3870 noformat=yuv420p,vflip
3874 Convert the input video to any of the formats not contained in the list:
3876 noformat=yuv420p:yuv444p:yuv410p
3882 Add noise on video input frame.
3884 This filter accepts a list of options in the form of @var{key}=@var{value}
3885 pairs separated by ":". A description of the accepted options follows.
3893 Set noise seed for specific pixel component or all pixel components in case
3894 of @var{all_seed}. Default value is @code{123457}.
3896 @item all_strength, alls
3897 @item c0_strength, c0s
3898 @item c1_strength, c1s
3899 @item c2_strength, c2s
3900 @item c3_strength, c3s
3901 Set noise strength for specific pixel component or all pixel components in case
3902 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
3904 @item all_flags, allf
3909 Set pixel component flags or set flags for all components if @var{all_flags}.
3910 Available values for component flags are:
3913 averaged temporal noise (smoother)
3915 mix random noise with a (semi)regular pattern
3917 higher quality (slightly better looking, slightly slower)
3919 temporal noise (noise pattern changes between frames)
3921 uniform noise (gaussian otherwise)
3925 @subsection Examples
3927 Add temporal and uniform noise to input video:
3929 noise=alls=20:allf=t+u
3934 Pass the video source unchanged to the output.
3938 Apply video transform using libopencv.
3940 To enable this filter install libopencv library and headers and
3941 configure FFmpeg with @code{--enable-libopencv}.
3943 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
3945 @var{filter_name} is the name of the libopencv filter to apply.
3947 @var{filter_params} specifies the parameters to pass to the libopencv
3948 filter. If not specified the default values are assumed.
3950 Refer to the official libopencv documentation for more precise
3952 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
3954 Follows the list of supported libopencv filters.
3959 Dilate an image by using a specific structuring element.
3960 This filter corresponds to the libopencv function @code{cvDilate}.
3962 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
3964 @var{struct_el} represents a structuring element, and has the syntax:
3965 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
3967 @var{cols} and @var{rows} represent the number of columns and rows of
3968 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
3969 point, and @var{shape} the shape for the structuring element, and
3970 can be one of the values "rect", "cross", "ellipse", "custom".
3972 If the value for @var{shape} is "custom", it must be followed by a
3973 string of the form "=@var{filename}". The file with name
3974 @var{filename} is assumed to represent a binary image, with each
3975 printable character corresponding to a bright pixel. When a custom
3976 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
3977 or columns and rows of the read file are assumed instead.
3979 The default value for @var{struct_el} is "3x3+0x0/rect".
3981 @var{nb_iterations} specifies the number of times the transform is
3982 applied to the image, and defaults to 1.
3984 Follow some example:
3986 # use the default values
3989 # dilate using a structuring element with a 5x5 cross, iterate two times
3990 ocv=dilate=5x5+2x2/cross:2
3992 # read the shape from the file diamond.shape, iterate two times
3993 # the file diamond.shape may contain a pattern of characters like this:
3999 # the specified cols and rows are ignored (but not the anchor point coordinates)
4000 ocv=0x0+2x2/custom=diamond.shape:2
4005 Erode an image by using a specific structuring element.
4006 This filter corresponds to the libopencv function @code{cvErode}.
4008 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4009 with the same syntax and semantics as the @ref{dilate} filter.
4013 Smooth the input video.
4015 The filter takes the following parameters:
4016 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
4018 @var{type} is the type of smooth filter to apply, and can be one of
4019 the following values: "blur", "blur_no_scale", "median", "gaussian",
4020 "bilateral". The default value is "gaussian".
4022 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
4023 parameters whose meanings depend on smooth type. @var{param1} and
4024 @var{param2} accept integer positive values or 0, @var{param3} and
4025 @var{param4} accept float values.
4027 The default value for @var{param1} is 3, the default value for the
4028 other parameters is 0.
4030 These parameters correspond to the parameters assigned to the
4031 libopencv function @code{cvSmooth}.
4036 Overlay one video on top of another.
4038 It takes two inputs and one output, the first input is the "main"
4039 video on which the second input is overlayed.
4041 This filter accepts a list of @var{key}=@var{value} pairs as argument,
4042 separated by ":". If the key of the first options is omitted, the
4043 arguments are interpreted according to the syntax @var{x}:@var{y}.
4045 A description of the accepted options follows.
4049 Set the expression for the x and y coordinates of the overlayed video
4050 on the main video. Default value is 0.
4052 The @var{x} and @var{y} expressions can contain the following
4055 @item main_w, main_h
4056 main input width and height
4059 same as @var{main_w} and @var{main_h}
4061 @item overlay_w, overlay_h
4062 overlay input width and height
4065 same as @var{overlay_w} and @var{overlay_h}
4069 Set the format for the output video.
4071 It accepts the following values:
4083 Default value is @samp{yuv420}.
4085 @item rgb @emph{(deprecated)}
4086 If set to 1, force the filter to accept inputs in the RGB
4087 color space. Default value is 0. This option is deprecated, use
4088 @option{format} instead.
4091 If set to 1, force the output to terminate when the shortest input
4092 terminates. Default value is 0.
4095 Be aware that frames are taken from each input video in timestamp
4096 order, hence, if their initial timestamps differ, it is a a good idea
4097 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4098 have them begin in the same zero timestamp, as it does the example for
4099 the @var{movie} filter.
4101 You can chain together more overlays but you should test the
4102 efficiency of such approach.
4104 @subsection Examples
4108 Draw the overlay at 10 pixels from the bottom right corner of the main
4111 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4114 Using named options the example above becomes:
4116 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4120 Insert a transparent PNG logo in the bottom left corner of the input,
4121 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4123 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4127 Insert 2 different transparent PNG logos (second logo on bottom
4128 right corner) using the @command{ffmpeg} tool:
4130 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
4134 Add a transparent color layer on top of the main video, WxH specifies
4135 the size of the main input to the overlay filter:
4137 color=red@@.3:WxH [over]; [in][over] overlay [out]
4141 Play an original video and a filtered version (here with the deshake
4142 filter) side by side using the @command{ffplay} tool:
4144 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4147 The above command is the same as:
4149 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4153 Compose output by putting two input videos side to side:
4155 ffmpeg -i left.avi -i right.avi -filter_complex "
4156 nullsrc=size=200x100 [background];
4157 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4158 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4159 [background][left] overlay=shortest=1 [background+left];
4160 [background+left][right] overlay=shortest=1:x=100 [left+right]
4165 Chain several overlays in cascade:
4167 nullsrc=s=200x200 [bg];
4168 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4169 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4170 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4171 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4172 [in3] null, [mid2] overlay=100:100 [out0]
4179 Add paddings to the input image, and place the original input at the
4180 given coordinates @var{x}, @var{y}.
4182 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
4185 If the key of the first options is omitted, the arguments are
4186 interpreted according to the syntax
4187 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
4189 A description of the accepted options follows.
4194 Specify an expression for the size of the output image with the
4195 paddings added. If the value for @var{width} or @var{height} is 0, the
4196 corresponding input size is used for the output.
4198 The @var{width} expression can reference the value set by the
4199 @var{height} expression, and vice versa.
4201 The default value of @var{width} and @var{height} is 0.
4205 Specify an expression for the offsets where to place the input image
4206 in the padded area with respect to the top/left border of the output
4209 The @var{x} expression can reference the value set by the @var{y}
4210 expression, and vice versa.
4212 The default value of @var{x} and @var{y} is 0.
4215 Specify the color of the padded area, it can be the name of a color
4216 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4218 The default value of @var{color} is "black".
4221 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4222 options are expressions containing the following constants:
4226 the input video width and height
4229 same as @var{in_w} and @var{in_h}
4232 the output width and height, that is the size of the padded area as
4233 specified by the @var{width} and @var{height} expressions
4236 same as @var{out_w} and @var{out_h}
4239 x and y offsets as specified by the @var{x} and @var{y}
4240 expressions, or NAN if not yet specified
4243 same as @var{iw} / @var{ih}
4246 input sample aspect ratio
4249 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4252 horizontal and vertical chroma subsample values. For example for the
4253 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4256 @subsection Examples
4260 Add paddings with color "violet" to the input video. Output video
4261 size is 640x480, the top-left corner of the input video is placed at
4264 pad=640:480:0:40:violet
4267 The example above is equivalent to the following command:
4269 pad=width=640:height=480:x=0:y=40:color=violet
4273 Pad the input to get an output with dimensions increased by 3/2,
4274 and put the input video at the center of the padded area:
4276 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4280 Pad the input to get a squared output with size equal to the maximum
4281 value between the input width and height, and put the input video at
4282 the center of the padded area:
4284 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4288 Pad the input to get a final w/h ratio of 16:9:
4290 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4294 In case of anamorphic video, in order to set the output display aspect
4295 correctly, it is necessary to use @var{sar} in the expression,
4296 according to the relation:
4298 (ih * X / ih) * sar = output_dar
4299 X = output_dar / sar
4302 Thus the previous example needs to be modified to:
4304 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4308 Double output size and put the input video in the bottom-right
4309 corner of the output padded area:
4311 pad="2*iw:2*ih:ow-iw:oh-ih"
4315 @section pixdesctest
4317 Pixel format descriptor test filter, mainly useful for internal
4318 testing. The output video should be equal to the input video.
4322 format=monow, pixdesctest
4325 can be used to test the monowhite pixel format descriptor definition.
4329 Enable the specified chain of postprocessing subfilters using libpostproc. This
4330 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4331 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4332 Each subfilter and some options have a short and a long name that can be used
4333 interchangeably, i.e. dr/dering are the same.
4335 All subfilters share common options to determine their scope:
4339 Honor the quality commands for this subfilter.
4342 Do chrominance filtering, too (default).
4345 Do luminance filtering only (no chrominance).
4348 Do chrominance filtering only (no luminance).
4351 These options can be appended after the subfilter name, separated by a ':'.
4353 Available subfilters are:
4356 @item hb/hdeblock[:difference[:flatness]]
4357 Horizontal deblocking filter
4360 Difference factor where higher values mean more deblocking (default: @code{32}).
4362 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4365 @item vb/vdeblock[:difference[:flatness]]
4366 Vertical deblocking filter
4369 Difference factor where higher values mean more deblocking (default: @code{32}).
4371 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4374 @item ha/hadeblock[:difference[:flatness]]
4375 Accurate horizontal deblocking filter
4378 Difference factor where higher values mean more deblocking (default: @code{32}).
4380 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4383 @item va/vadeblock[:difference[:flatness]]
4384 Accurate vertical deblocking filter
4387 Difference factor where higher values mean more deblocking (default: @code{32}).
4389 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4393 The horizontal and vertical deblocking filters share the difference and
4394 flatness values so you cannot set different horizontal and vertical
4399 Experimental horizontal deblocking filter
4402 Experimental vertical deblocking filter
4407 @item tn/tmpnoise[:threshold1[:threshold2[:threshold3]]], temporal noise reducer
4410 larger -> stronger filtering
4412 larger -> stronger filtering
4414 larger -> stronger filtering
4417 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4420 Stretch luminance to @code{0-255}.
4423 @item lb/linblenddeint
4424 Linear blend deinterlacing filter that deinterlaces the given block by
4425 filtering all lines with a @code{(1 2 1)} filter.
4427 @item li/linipoldeint
4428 Linear interpolating deinterlacing filter that deinterlaces the given block by
4429 linearly interpolating every second line.
4431 @item ci/cubicipoldeint
4432 Cubic interpolating deinterlacing filter deinterlaces the given block by
4433 cubically interpolating every second line.
4435 @item md/mediandeint
4436 Median deinterlacing filter that deinterlaces the given block by applying a
4437 median filter to every second line.
4439 @item fd/ffmpegdeint
4440 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4441 second line with a @code{(-1 4 2 4 -1)} filter.
4444 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4445 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4447 @item fq/forceQuant[:quantizer]
4448 Overrides the quantizer table from the input with the constant quantizer you
4456 Default pp filter combination (@code{hb:a,vb:a,dr:a})
4459 Fast pp filter combination (@code{h1:a,v1:a,dr:a})
4462 High quality pp filter combination (@code{ha:a:128:7,va:a,dr:a})
4465 @subsection Examples
4469 Apply horizontal and vertical deblocking, deringing and automatic
4470 brightness/contrast:
4476 Apply default filters without brightness/contrast correction:
4482 Apply default filters and temporal denoiser:
4484 pp=default/tmpnoise:1:2:3
4488 Apply deblocking on luminance only, and switch vertical deblocking on or off
4489 automatically depending on available CPU time:
4497 Suppress a TV station logo, using an image file to determine which
4498 pixels comprise the logo. It works by filling in the pixels that
4499 comprise the logo with neighboring pixels.
4501 This filter requires one argument which specifies the filter bitmap
4502 file, which can be any image format supported by libavformat. The
4503 width and height of the image file must match those of the video
4504 stream being processed.
4506 Pixels in the provided bitmap image with a value of zero are not
4507 considered part of the logo, non-zero pixels are considered part of
4508 the logo. If you use white (255) for the logo and black (0) for the
4509 rest, you will be safe. For making the filter bitmap, it is
4510 recommended to take a screen capture of a black frame with the logo
4511 visible, and then using a threshold filter followed by the erode
4512 filter once or twice.
4514 If needed, little splotches can be fixed manually. Remember that if
4515 logo pixels are not covered, the filter quality will be much
4516 reduced. Marking too many pixels as part of the logo does not hurt as
4517 much, but it will increase the amount of blurring needed to cover over
4518 the image and will destroy more information than necessary, and extra
4519 pixels will slow things down on a large logo.
4523 Scale (resize) the input video, using the libswscale library.
4525 The scale filter forces the output display aspect ratio to be the same
4526 of the input, by changing the output sample aspect ratio.
4528 This filter accepts a list of named options in the form of
4529 @var{key}=@var{value} pairs separated by ":". If the key for the first
4530 two options is not specified, the assumed keys for the first two
4531 values are @code{w} and @code{h}. If the first option has no key and
4532 can be interpreted like a video size specification, it will be used
4533 to set the video size.
4535 A description of the accepted options follows.
4539 Set the video width expression, default value is @code{iw}. See below
4540 for the list of accepted constants.
4543 Set the video heiht expression, default value is @code{ih}.
4544 See below for the list of accepted constants.
4547 Set the interlacing. It accepts the following values:
4551 force interlaced aware scaling
4554 do not apply interlaced scaling
4557 select interlaced aware scaling depending on whether the source frames
4558 are flagged as interlaced or not
4561 Default value is @code{0}.
4564 Set libswscale scaling flags. If not explictly specified the filter
4565 applies a bilinear scaling algorithm.
4568 Set the video size, the value must be a valid abbreviation or in the
4569 form @var{width}x@var{height}.
4572 The values of the @var{w} and @var{h} options are expressions
4573 containing the following constants:
4577 the input width and height
4580 same as @var{in_w} and @var{in_h}
4583 the output (cropped) width and height
4586 same as @var{out_w} and @var{out_h}
4589 same as @var{iw} / @var{ih}
4592 input sample aspect ratio
4595 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4598 horizontal and vertical chroma subsample values. For example for the
4599 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4602 If the input image format is different from the format requested by
4603 the next filter, the scale filter will convert the input to the
4606 If the value for @var{width} or @var{height} is 0, the respective input
4607 size is used for the output.
4609 If the value for @var{width} or @var{height} is -1, the scale filter will
4610 use, for the respective output size, a value that maintains the aspect
4611 ratio of the input image.
4613 @subsection Examples
4617 Scale the input video to a size of 200x100:
4622 This is equivalent to:
4633 Specify a size abbreviation for the output size:
4638 which can also be written as:
4644 Scale the input to 2x:
4650 The above is the same as:
4656 Scale the input to 2x with forced interlaced scaling:
4658 scale=2*iw:2*ih:interl=1
4662 Scale the input to half size:
4668 Increase the width, and set the height to the same size:
4674 Seek for Greek harmony:
4681 Increase the height, and set the width to 3/2 of the height:
4687 Increase the size, but make the size a multiple of the chroma:
4689 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4693 Increase the width to a maximum of 500 pixels, keep the same input
4696 scale='min(500\, iw*3/2):-1'
4700 @section setdar, setsar
4702 The @code{setdar} filter sets the Display Aspect Ratio for the filter
4705 This is done by changing the specified Sample (aka Pixel) Aspect
4706 Ratio, according to the following equation:
4708 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
4711 Keep in mind that the @code{setdar} filter does not modify the pixel
4712 dimensions of the video frame. Also the display aspect ratio set by
4713 this filter may be changed by later filters in the filterchain,
4714 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
4717 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
4718 the filter output video.
4720 Note that as a consequence of the application of this filter, the
4721 output display aspect ratio will change according to the equation
4724 Keep in mind that the sample aspect ratio set by the @code{setsar}
4725 filter may be changed by later filters in the filterchain, e.g. if
4726 another "setsar" or a "setdar" filter is applied.
4728 The @code{setdar} and @code{setsar} filters accept a string in the
4729 form @var{num}:@var{den} expressing an aspect ratio, or the following
4730 named options, expressed as a sequence of @var{key}=@var{value} pairs,
4735 Set the maximum integer value to use for expressing numerator and
4736 denominator when reducing the expressed aspect ratio to a rational.
4737 Default value is @code{100}.
4740 Set the aspect ratio used by the filter.
4742 The parameter can be a floating point number string, an expression, or
4743 a string of the form @var{num}:@var{den}, where @var{num} and
4744 @var{den} are the numerator and denominator of the aspect ratio. If
4745 the parameter is not specified, it is assumed the value "0".
4746 In case the form "@var{num}:@var{den}" the @code{:} character should
4750 If the keys are omitted in the named options list, the specifed values
4751 are assumed to be @var{ratio} and @var{max} in that order.
4753 For example to change the display aspect ratio to 16:9, specify:
4758 The example above is equivalent to:
4763 To change the sample aspect ratio to 10:11, specify:
4768 To set a display aspect ratio of 16:9, and specify a maximum integer value of
4769 1000 in the aspect ratio reduction, use the command:
4771 setdar=ratio='16:9':max=1000
4776 Force field for the output video frame.
4778 The @code{setfield} filter marks the interlace type field for the
4779 output frames. It does not change the input frame, but only sets the
4780 corresponding property, which affects how the frame is treated by
4781 following filters (e.g. @code{fieldorder} or @code{yadif}).
4783 This filter accepts a single option @option{mode}, which can be
4784 specified either by setting @code{mode=VALUE} or setting the value
4785 alone. Available values are:
4789 Keep the same field property.
4792 Mark the frame as bottom-field-first.
4795 Mark the frame as top-field-first.
4798 Mark the frame as progressive.
4803 Show a line containing various information for each input video frame.
4804 The input video is not modified.
4806 The shown line contains a sequence of key/value pairs of the form
4807 @var{key}:@var{value}.
4809 A description of each shown parameter follows:
4813 sequential number of the input frame, starting from 0
4816 Presentation TimeStamp of the input frame, expressed as a number of
4817 time base units. The time base unit depends on the filter input pad.
4820 Presentation TimeStamp of the input frame, expressed as a number of
4824 position of the frame in the input stream, -1 if this information in
4825 unavailable and/or meaningless (for example in case of synthetic video)
4831 sample aspect ratio of the input frame, expressed in the form
4835 size of the input frame, expressed in the form
4836 @var{width}x@var{height}
4839 interlaced mode ("P" for "progressive", "T" for top field first, "B"
4840 for bottom field first)
4843 1 if the frame is a key frame, 0 otherwise
4846 picture type of the input frame ("I" for an I-frame, "P" for a
4847 P-frame, "B" for a B-frame, "?" for unknown type).
4848 Check also the documentation of the @code{AVPictureType} enum and of
4849 the @code{av_get_picture_type_char} function defined in
4850 @file{libavutil/avutil.h}.
4853 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
4855 @item plane_checksum
4856 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
4857 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
4862 Blur the input video without impacting the outlines.
4864 The filter accepts the following parameters:
4865 @var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
4867 Parameters prefixed by @var{luma} indicate that they work on the
4868 luminance of the pixels whereas parameters prefixed by @var{chroma}
4869 refer to the chrominance of the pixels.
4871 If the chroma parameters are not set, the luma parameters are used for
4872 either the luminance and the chrominance of the pixels.
4874 @var{luma_radius} or @var{chroma_radius} must be a float number in the
4875 range [0.1,5.0] that specifies the variance of the gaussian filter
4876 used to blur the image (slower if larger).
4878 @var{luma_strength} or @var{chroma_strength} must be a float number in
4879 the range [-1.0,1.0] that configures the blurring. A value included in
4880 [0.0,1.0] will blur the image whereas a value included in [-1.0,0.0]
4881 will sharpen the image.
4883 @var{luma_threshold} or @var{chroma_threshold} must be an integer in
4884 the range [-30,30] that is used as a coefficient to determine whether
4885 a pixel should be blurred or not. A value of 0 will filter all the
4886 image, a value included in [0,30] will filter flat areas and a value
4887 included in [-30,0] will filter edges.
4891 Convert between different stereoscopic image formats.
4893 This filter accepts the following named options, expressed as a
4894 sequence of @var{key}=@var{value} pairs, separated by ":".
4898 Set stereoscopic image format of input.
4900 Available values for input image formats are:
4903 side by side parallel (left eye left, right eye right)
4906 side by side crosseye (right eye left, left eye right)
4909 side by side parallel with half width resolution
4910 (left eye left, right eye right)
4913 side by side crosseye with half width resolution
4914 (right eye left, left eye right)
4917 above-below (left eye above, right eye below)
4920 above-below (right eye above, left eye below)
4923 above-below with half height resolution
4924 (left eye above, right eye below)
4927 above-below with half height resolution
4928 (right eye above, left eye below)
4930 Default value is @samp{sbsl}.
4934 Set stereoscopic image format of output.
4936 Available values for output image formats are all the input formats as well as:
4939 anaglyph red/blue gray
4940 (red filter on left eye, blue filter on right eye)
4943 anaglyph red/green gray
4944 (red filter on left eye, green filter on right eye)
4947 anaglyph red/cyan gray
4948 (red filter on left eye, cyan filter on right eye)
4951 anaglyph red/cyan half colored
4952 (red filter on left eye, cyan filter on right eye)
4955 anaglyph red/cyan color
4956 (red filter on left eye, cyan filter on right eye)
4959 anaglyph red/cyan color optimized with the least squares projection of dubois
4960 (red filter on left eye, cyan filter on right eye)
4963 anaglyph green/magenta gray
4964 (green filter on left eye, magenta filter on right eye)
4967 anaglyph green/magenta half colored
4968 (green filter on left eye, magenta filter on right eye)
4971 anaglyph green/magenta colored
4972 (green filter on left eye, magenta filter on right eye)
4975 anaglyph green/magenta color optimized with the least squares projection of dubois
4976 (green filter on left eye, magenta filter on right eye)
4979 anaglyph yellow/blue gray
4980 (yellow filter on left eye, blue filter on right eye)
4983 anaglyph yellow/blue half colored
4984 (yellow filter on left eye, blue filter on right eye)
4987 anaglyph yellow/blue colored
4988 (yellow filter on left eye, blue filter on right eye)
4991 anaglyph yellow/blue color optimized with the least squares projection of dubois
4992 (yellow filter on left eye, blue filter on right eye)
4995 interleaved rows (left eye has top row, right eye starts on next row)
4998 interleaved rows (right eye has top row, left eye starts on next row)
5001 mono output (left eye only)
5004 mono output (right eye only)
5007 Default value is @samp{arcd}.
5013 Draw subtitles on top of input video using the libass library.
5015 To enable compilation of this filter you need to configure FFmpeg with
5016 @code{--enable-libass}. This filter also requires a build with libavcodec and
5017 libavformat to convert the passed subtitles file to ASS (Advanced Substation
5018 Alpha) subtitles format.
5020 This filter accepts the following named options, expressed as a
5021 sequence of @var{key}=@var{value} pairs, separated by ":".
5025 Set the filename of the subtitle file to read. It must be specified.
5028 Specify the size of the original video, the video for which the ASS file
5029 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
5030 necessary to correctly scale the fonts if the aspect ratio has been changed.
5033 Set subtitles input character encoding. @code{subtitles} filter only. Only
5034 useful if not UTF-8.
5037 If the first key is not specified, it is assumed that the first value
5038 specifies the @option{filename}.
5040 For example, to render the file @file{sub.srt} on top of the input
5041 video, use the command:
5046 which is equivalent to:
5048 subtitles=filename=sub.srt
5053 Split input video into several identical outputs.
5055 The filter accepts a single parameter which specifies the number of outputs. If
5056 unspecified, it defaults to 2.
5060 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
5062 will create 5 copies of the input video.
5066 [in] split [splitout1][splitout2];
5067 [splitout1] crop=100:100:0:0 [cropout];
5068 [splitout2] pad=200:200:100:100 [padout];
5071 will create two separate outputs from the same input, one cropped and
5076 Scale the input by 2x and smooth using the Super2xSaI (Scale and
5077 Interpolate) pixel art scaling algorithm.
5079 Useful for enlarging pixel art images without reducing sharpness.
5085 Select the most representative frame in a given sequence of consecutive frames.
5087 It accepts as argument the frames batch size to analyze (default @var{N}=100);
5088 in a set of @var{N} frames, the filter will pick one of them, and then handle
5089 the next batch of @var{N} frames until the end.
5091 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
5092 value will result in a higher memory usage, so a high value is not recommended.
5094 The following example extract one picture each 50 frames:
5099 Complete example of a thumbnail creation with @command{ffmpeg}:
5101 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
5106 Tile several successive frames together.
5108 It accepts a list of options in the form of @var{key}=@var{value} pairs
5109 separated by ":". A description of the accepted options follows.
5114 Set the grid size (i.e. the number of lines and columns) in the form
5118 Set the outer border margin in pixels.
5121 Set the inner border thickness (i.e. the number of pixels between frames). For
5122 more advanced padding options (such as having different values for the edges),
5123 refer to the pad video filter.
5126 Set the maximum number of frames to render in the given area. It must be less
5127 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
5128 the area will be used.
5132 Alternatively, the options can be specified as a flat string:
5134 @var{layout}[:@var{nb_frames}[:@var{margin}[:@var{padding}]]]
5136 For example, produce 8x8 PNG tiles of all keyframes (@option{-skip_frame
5139 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
5141 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
5142 duplicating each output frame to accomodate the originally detected frame
5145 Another example to display @code{5} pictures in an area of @code{3x2} frames,
5146 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
5147 mixed flat and named options:
5149 tile=3x2:nb_frames=5:padding=7:margin=2
5154 Perform various types of temporal field interlacing.
5156 Frames are counted starting from 1, so the first input frame is
5159 This filter accepts options in the form of @var{key}=@var{value} pairs
5161 Alternatively, the @var{mode} option can be specified as a value alone,
5162 optionally followed by a ":" and further ":" separated @var{key}=@var{value}
5165 A description of the accepted options follows.
5170 Specify the mode of the interlacing. This option can also be specified
5171 as a value alone. See below for a list of values for this option.
5173 Available values are:
5177 Move odd frames into the upper field, even into the lower field,
5178 generating a double height frame at half framerate.
5181 Only output even frames, odd frames are dropped, generating a frame with
5182 unchanged height at half framerate.
5185 Only output odd frames, even frames are dropped, generating a frame with
5186 unchanged height at half framerate.
5189 Expand each frame to full height, but pad alternate lines with black,
5190 generating a frame with double height at the same input framerate.
5192 @item interleave_top, 4
5193 Interleave the upper field from odd frames with the lower field from
5194 even frames, generating a frame with unchanged height at half framerate.
5196 @item interleave_bottom, 5
5197 Interleave the lower field from odd frames with the upper field from
5198 even frames, generating a frame with unchanged height at half framerate.
5200 @item interlacex2, 6
5201 Double frame rate with unchanged height. Frames are inserted each
5202 containing the second temporal field from the previous input frame and
5203 the first temporal field from the next input frame. This mode relies on
5204 the top_field_first flag. Useful for interlaced video displays with no
5205 field synchronisation.
5208 Numeric values are deprecated but are accepted for backward
5209 compatibility reasons.
5211 Default mode is @code{merge}.
5214 Specify flags influencing the filter process.
5216 Available value for @var{flags} is:
5219 @item low_pass_filter, vlfp
5220 Enable vertical low-pass filtering in the filter.
5221 Vertical low-pass filtering is required when creating an interlaced
5222 destination from a progressive source which contains high-frequency
5223 vertical detail. Filtering will reduce interlace 'twitter' and Moire
5226 Vertical low-pass filtering can only be enabled for @option{mode}
5227 @var{interleave_top} and @var{interleave_bottom}.
5234 Transpose rows with columns in the input video and optionally flip it.
5236 The filter accepts parameters as a list of @var{key}=@var{value}
5237 pairs, separated by ':'. If the key of the first options is omitted,
5238 the arguments are interpreted according to the syntax
5239 @var{dir}:@var{passthrough}.
5243 Specify the transposition direction. Can assume the following values:
5247 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
5255 Rotate by 90 degrees clockwise, that is:
5263 Rotate by 90 degrees counterclockwise, that is:
5271 Rotate by 90 degrees clockwise and vertically flip, that is:
5279 For values between 4-7, the transposition is only done if the input
5280 video geometry is portrait and not landscape. These values are
5281 deprecated, the @code{passthrough} option should be used instead.
5284 Do not apply the transposition if the input geometry matches the one
5285 specified by the specified value. It accepts the following values:
5288 Always apply transposition.
5290 Preserve portrait geometry (when @var{height} >= @var{width}).
5292 Preserve landscape geometry (when @var{width} >= @var{height}).
5295 Default value is @code{none}.
5298 For example to rotate by 90 degrees clockwise and preserve portrait
5301 transpose=dir=1:passthrough=portrait
5304 The command above can also be specified as:
5306 transpose=1:portrait
5311 Sharpen or blur the input video.
5313 This filter accepts parameters as a list of @var{key}=@var{value} pairs,
5316 If the key of the first options is omitted, the arguments are
5317 interpreted according to the syntax:
5318 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
5320 A description of the accepted options follows.
5323 @item luma_msize_x, lx
5324 @item chroma_msize_x, cx
5325 Set the luma/chroma matrix horizontal size. It must be an odd integer
5326 between 3 and 63, default value is 5.
5328 @item luma_msize_y, ly
5329 @item chroma_msize_y, cy
5330 Set the luma/chroma matrix vertical size. It must be an odd integer
5331 between 3 and 63, default value is 5.
5333 @item luma_amount, la
5334 @item chroma_amount, ca
5335 Set the luma/chroma effect strength. It can be a float number,
5336 reasonable values lay between -1.5 and 1.5.
5338 Negative values will blur the input video, while positive values will
5339 sharpen it, a value of zero will disable the effect.
5341 Default value is 1.0 for @option{luma_amount}, 0.0 for
5342 @option{chroma_amount}.
5345 @subsection Examples
5349 Apply strong luma sharpen effect:
5355 Apply strong blur of both luma and chroma parameters:
5357 unsharp=7:7:-2:7:7:-2
5363 Flip the input video vertically.
5366 ffmpeg -i in.avi -vf "vflip" out.avi
5371 Deinterlace the input video ("yadif" means "yet another deinterlacing
5374 The filter accepts parameters as a list of @var{key}=@var{value}
5375 pairs, separated by ":". If the key of the first options is omitted,
5376 the arguments are interpreted according to syntax
5377 @var{mode}:@var{parity}:@var{deint}.
5379 The description of the accepted parameters follows.
5383 Specify the interlacing mode to adopt. Accept one of the following
5388 output 1 frame for each frame
5390 output 1 frame for each field
5391 @item 2, send_frame_nospatial
5392 like @code{send_frame} but skip spatial interlacing check
5393 @item 3, send_field_nospatial
5394 like @code{send_field} but skip spatial interlacing check
5397 Default value is @code{send_frame}.
5400 Specify the picture field parity assumed for the input interlaced
5401 video. Accept one of the following values:
5405 assume top field first
5407 assume bottom field first
5409 enable automatic detection
5412 Default value is @code{auto}.
5413 If interlacing is unknown or decoder does not export this information,
5414 top field first will be assumed.
5417 Specify which frames to deinterlace. Accept one of the following
5422 deinterlace all frames
5424 only deinterlace frames marked as interlaced
5427 Default value is @code{all}.
5430 @c man end VIDEO FILTERS
5432 @chapter Video Sources
5433 @c man begin VIDEO SOURCES
5435 Below is a description of the currently available video sources.
5439 Buffer video frames, and make them available to the filter chain.
5441 This source is mainly intended for a programmatic use, in particular
5442 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5444 It accepts a list of options in the form of @var{key}=@var{value} pairs
5445 separated by ":". A description of the accepted options follows.
5450 Specify the size (width and height) of the buffered video frames.
5453 A string representing the pixel format of the buffered video frames.
5454 It may be a number corresponding to a pixel format, or a pixel format
5458 Specify the timebase assumed by the timestamps of the buffered frames.
5461 Specify the frame rate expected for the video stream.
5464 Specify the sample aspect ratio assumed by the video frames.
5467 Specify the optional parameters to be used for the scale filter which
5468 is automatically inserted when an input change is detected in the
5469 input size or format.
5474 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
5477 will instruct the source to accept video frames with size 320x240 and
5478 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5479 square pixels (1:1 sample aspect ratio).
5480 Since the pixel format with name "yuv410p" corresponds to the number 6
5481 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5482 this example corresponds to:
5484 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5487 Alternatively, the options can be specified as a flat string, but this
5488 syntax is deprecated:
5490 @var{width}:@var{height}:@var{pix_fmt}:@var{time_base.num}:@var{time_base.den}:@var{pixel_aspect.num}:@var{pixel_aspect.den}[:@var{sws_param}]
5494 Create a pattern generated by an elementary cellular automaton.
5496 The initial state of the cellular automaton can be defined through the
5497 @option{filename}, and @option{pattern} options. If such options are
5498 not specified an initial state is created randomly.
5500 At each new frame a new row in the video is filled with the result of
5501 the cellular automaton next generation. The behavior when the whole
5502 frame is filled is defined by the @option{scroll} option.
5504 This source accepts a list of options in the form of
5505 @var{key}=@var{value} pairs separated by ":". A description of the
5506 accepted options follows.
5510 Read the initial cellular automaton state, i.e. the starting row, from
5512 In the file, each non-whitespace character is considered an alive
5513 cell, a newline will terminate the row, and further characters in the
5514 file will be ignored.
5517 Read the initial cellular automaton state, i.e. the starting row, from
5518 the specified string.
5520 Each non-whitespace character in the string is considered an alive
5521 cell, a newline will terminate the row, and further characters in the
5522 string will be ignored.
5525 Set the video rate, that is the number of frames generated per second.
5528 @item random_fill_ratio, ratio
5529 Set the random fill ratio for the initial cellular automaton row. It
5530 is a floating point number value ranging from 0 to 1, defaults to
5533 This option is ignored when a file or a pattern is specified.
5535 @item random_seed, seed
5536 Set the seed for filling randomly the initial row, must be an integer
5537 included between 0 and UINT32_MAX. If not specified, or if explicitly
5538 set to -1, the filter will try to use a good random seed on a best
5542 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5543 Default value is 110.
5546 Set the size of the output video.
5548 If @option{filename} or @option{pattern} is specified, the size is set
5549 by default to the width of the specified initial state row, and the
5550 height is set to @var{width} * PHI.
5552 If @option{size} is set, it must contain the width of the specified
5553 pattern string, and the specified pattern will be centered in the
5556 If a filename or a pattern string is not specified, the size value
5557 defaults to "320x518" (used for a randomly generated initial state).
5560 If set to 1, scroll the output upward when all the rows in the output
5561 have been already filled. If set to 0, the new generated row will be
5562 written over the top row just after the bottom row is filled.
5565 @item start_full, full
5566 If set to 1, completely fill the output with generated rows before
5567 outputting the first frame.
5568 This is the default behavior, for disabling set the value to 0.
5571 If set to 1, stitch the left and right row edges together.
5572 This is the default behavior, for disabling set the value to 0.
5575 @subsection Examples
5579 Read the initial state from @file{pattern}, and specify an output of
5582 cellauto=f=pattern:s=200x400
5586 Generate a random initial row with a width of 200 cells, with a fill
5589 cellauto=ratio=2/3:s=200x200
5593 Create a pattern generated by rule 18 starting by a single alive cell
5594 centered on an initial row with width 100:
5596 cellauto=p=@@:s=100x400:full=0:rule=18
5600 Specify a more elaborated initial pattern:
5602 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5609 Generate a Mandelbrot set fractal, and progressively zoom towards the
5610 point specified with @var{start_x} and @var{start_y}.
5612 This source accepts a list of options in the form of
5613 @var{key}=@var{value} pairs separated by ":". A description of the
5614 accepted options follows.
5619 Set the terminal pts value. Default value is 400.
5622 Set the terminal scale value.
5623 Must be a floating point value. Default value is 0.3.
5626 Set the inner coloring mode, that is the algorithm used to draw the
5627 Mandelbrot fractal internal region.
5629 It shall assume one of the following values:
5634 Show time until convergence.
5636 Set color based on point closest to the origin of the iterations.
5641 Default value is @var{mincol}.
5644 Set the bailout value. Default value is 10.0.
5647 Set the maximum of iterations performed by the rendering
5648 algorithm. Default value is 7189.
5651 Set outer coloring mode.
5652 It shall assume one of following values:
5654 @item iteration_count
5655 Set iteration cound mode.
5656 @item normalized_iteration_count
5657 set normalized iteration count mode.
5659 Default value is @var{normalized_iteration_count}.
5662 Set frame rate, expressed as number of frames per second. Default
5666 Set frame size. Default value is "640x480".
5669 Set the initial scale value. Default value is 3.0.
5672 Set the initial x position. Must be a floating point value between
5673 -100 and 100. Default value is -0.743643887037158704752191506114774.
5676 Set the initial y position. Must be a floating point value between
5677 -100 and 100. Default value is -0.131825904205311970493132056385139.
5682 Generate various test patterns, as generated by the MPlayer test filter.
5684 The size of the generated video is fixed, and is 256x256.
5685 This source is useful in particular for testing encoding features.
5687 This source accepts an optional sequence of @var{key}=@var{value} pairs,
5688 separated by ":". The description of the accepted options follows.
5693 Specify the frame rate of the sourced video, as the number of frames
5694 generated per second. It has to be a string in the format
5695 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5696 number or a valid video frame rate abbreviation. The default value is
5700 Set the video duration of the sourced video. The accepted syntax is:
5705 See also the function @code{av_parse_time()}.
5707 If not specified, or the expressed duration is negative, the video is
5708 supposed to be generated forever.
5712 Set the number or the name of the test to perform. Supported tests are:
5727 Default value is "all", which will cycle through the list of all tests.
5730 For example the following:
5735 will generate a "dc_luma" test pattern.
5739 Provide a frei0r source.
5741 To enable compilation of this filter you need to install the frei0r
5742 header and configure FFmpeg with @code{--enable-frei0r}.
5744 The source supports the syntax:
5746 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
5749 @var{size} is the size of the video to generate, may be a string of the
5750 form @var{width}x@var{height} or a frame size abbreviation.
5751 @var{rate} is the rate of the video to generate, may be a string of
5752 the form @var{num}/@var{den} or a frame rate abbreviation.
5753 @var{src_name} is the name to the frei0r source to load. For more
5754 information regarding frei0r and how to set the parameters read the
5755 section @ref{frei0r} in the description of the video filters.
5757 For example, to generate a frei0r partik0l source with size 200x200
5758 and frame rate 10 which is overlayed on the overlay filter main input:
5760 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
5765 Generate a life pattern.
5767 This source is based on a generalization of John Conway's life game.
5769 The sourced input represents a life grid, each pixel represents a cell
5770 which can be in one of two possible states, alive or dead. Every cell
5771 interacts with its eight neighbours, which are the cells that are
5772 horizontally, vertically, or diagonally adjacent.
5774 At each interaction the grid evolves according to the adopted rule,
5775 which specifies the number of neighbor alive cells which will make a
5776 cell stay alive or born. The @option{rule} option allows to specify
5779 This source accepts a list of options in the form of
5780 @var{key}=@var{value} pairs separated by ":". A description of the
5781 accepted options follows.
5785 Set the file from which to read the initial grid state. In the file,
5786 each non-whitespace character is considered an alive cell, and newline
5787 is used to delimit the end of each row.
5789 If this option is not specified, the initial grid is generated
5793 Set the video rate, that is the number of frames generated per second.
5796 @item random_fill_ratio, ratio
5797 Set the random fill ratio for the initial random grid. It is a
5798 floating point number value ranging from 0 to 1, defaults to 1/PHI.
5799 It is ignored when a file is specified.
5801 @item random_seed, seed
5802 Set the seed for filling the initial random grid, must be an integer
5803 included between 0 and UINT32_MAX. If not specified, or if explicitly
5804 set to -1, the filter will try to use a good random seed on a best
5810 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
5811 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
5812 @var{NS} specifies the number of alive neighbor cells which make a
5813 live cell stay alive, and @var{NB} the number of alive neighbor cells
5814 which make a dead cell to become alive (i.e. to "born").
5815 "s" and "b" can be used in place of "S" and "B", respectively.
5817 Alternatively a rule can be specified by an 18-bits integer. The 9
5818 high order bits are used to encode the next cell state if it is alive
5819 for each number of neighbor alive cells, the low order bits specify
5820 the rule for "borning" new cells. Higher order bits encode for an
5821 higher number of neighbor cells.
5822 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
5823 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
5825 Default value is "S23/B3", which is the original Conway's game of life
5826 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
5827 cells, and will born a new cell if there are three alive cells around
5831 Set the size of the output video.
5833 If @option{filename} is specified, the size is set by default to the
5834 same size of the input file. If @option{size} is set, it must contain
5835 the size specified in the input file, and the initial grid defined in
5836 that file is centered in the larger resulting area.
5838 If a filename is not specified, the size value defaults to "320x240"
5839 (used for a randomly generated initial grid).
5842 If set to 1, stitch the left and right grid edges together, and the
5843 top and bottom edges also. Defaults to 1.
5846 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
5847 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
5848 value from 0 to 255.
5851 Set the color of living (or new born) cells.
5854 Set the color of dead cells. If @option{mold} is set, this is the first color
5855 used to represent a dead cell.
5858 Set mold color, for definitely dead and moldy cells.
5861 @subsection Examples
5865 Read a grid from @file{pattern}, and center it on a grid of size
5868 life=f=pattern:s=300x300
5872 Generate a random grid of size 200x200, with a fill ratio of 2/3:
5874 life=ratio=2/3:s=200x200
5878 Specify a custom rule for evolving a randomly generated grid:
5884 Full example with slow death effect (mold) using @command{ffplay}:
5886 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
5890 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
5892 The @code{color} source provides an uniformly colored input.
5894 The @code{nullsrc} source returns unprocessed video frames. It is
5895 mainly useful to be employed in analysis / debugging tools, or as the
5896 source for filters which ignore the input data.
5898 The @code{rgbtestsrc} source generates an RGB test pattern useful for
5899 detecting RGB vs BGR issues. You should see a red, green and blue
5900 stripe from top to bottom.
5902 The @code{smptebars} source generates a color bars pattern, based on
5903 the SMPTE Engineering Guideline EG 1-1990.
5905 The @code{testsrc} source generates a test video pattern, showing a
5906 color pattern, a scrolling gradient and a timestamp. This is mainly
5907 intended for testing purposes.
5909 These sources accept an optional sequence of @var{key}=@var{value} pairs,
5910 separated by ":". The description of the accepted options follows.
5915 Specify the color of the source, only used in the @code{color}
5916 source. It can be the name of a color (case insensitive match) or a
5917 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
5918 default value is "black".
5921 Specify the size of the sourced video, it may be a string of the form
5922 @var{width}x@var{height}, or the name of a size abbreviation. The
5923 default value is "320x240".
5926 Specify the frame rate of the sourced video, as the number of frames
5927 generated per second. It has to be a string in the format
5928 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5929 number or a valid video frame rate abbreviation. The default value is
5933 Set the sample aspect ratio of the sourced video.
5936 Set the video duration of the sourced video. The accepted syntax is:
5938 [-]HH[:MM[:SS[.m...]]]
5941 See also the function @code{av_parse_time()}.
5943 If not specified, or the expressed duration is negative, the video is
5944 supposed to be generated forever.
5947 Set the number of decimals to show in the timestamp, only used in the
5948 @code{testsrc} source.
5950 The displayed timestamp value will correspond to the original
5951 timestamp value multiplied by the power of 10 of the specified
5952 value. Default value is 0.
5955 For example the following:
5957 testsrc=duration=5.3:size=qcif:rate=10
5960 will generate a video with a duration of 5.3 seconds, with size
5961 176x144 and a frame rate of 10 frames per second.
5963 The following graph description will generate a red source
5964 with an opacity of 0.2, with size "qcif" and a frame rate of 10
5967 color=c=red@@0.2:s=qcif:r=10
5970 If the input content is to be ignored, @code{nullsrc} can be used. The
5971 following command generates noise in the luminance plane by employing
5972 the @code{geq} filter:
5974 nullsrc=s=256x256, geq=random(1)*255:128:128
5977 @c man end VIDEO SOURCES
5979 @chapter Video Sinks
5980 @c man begin VIDEO SINKS
5982 Below is a description of the currently available video sinks.
5986 Buffer video frames, and make them available to the end of the filter
5989 This sink is mainly intended for a programmatic use, in particular
5990 through the interface defined in @file{libavfilter/buffersink.h}.
5992 It does not require a string parameter in input, but you need to
5993 specify a pointer to a list of supported pixel formats terminated by
5994 -1 in the opaque parameter provided to @code{avfilter_init_filter}
5995 when initializing this sink.
5999 Null video sink, do absolutely nothing with the input video. It is
6000 mainly useful as a template and to be employed in analysis / debugging
6003 @c man end VIDEO SINKS
6005 @chapter Multimedia Filters
6006 @c man begin MULTIMEDIA FILTERS
6008 Below is a description of the currently available multimedia filters.
6010 @section aselect, select
6011 Select frames to pass in output.
6013 These filters accept a single option @option{expr} or @option{e}
6014 specifying the select expression, which can be specified either by
6015 specyfing @code{expr=VALUE} or specifying the expression
6018 The select expression is evaluated for each input frame. If the
6019 evaluation result is a non-zero value, the frame is selected and
6020 passed to the output, otherwise it is discarded.
6022 The expression can contain the following constants:
6026 the sequential number of the filtered frame, starting from 0
6029 the sequential number of the selected frame, starting from 0
6031 @item prev_selected_n
6032 the sequential number of the last selected frame, NAN if undefined
6035 timebase of the input timestamps
6038 the PTS (Presentation TimeStamp) of the filtered video frame,
6039 expressed in @var{TB} units, NAN if undefined
6042 the PTS (Presentation TimeStamp) of the filtered video frame,
6043 expressed in seconds, NAN if undefined
6046 the PTS of the previously filtered video frame, NAN if undefined
6048 @item prev_selected_pts
6049 the PTS of the last previously filtered video frame, NAN if undefined
6051 @item prev_selected_t
6052 the PTS of the last previously selected video frame, NAN if undefined
6055 the PTS of the first video frame in the video, NAN if undefined
6058 the time of the first video frame in the video, NAN if undefined
6060 @item pict_type @emph{(video only)}
6061 the type of the filtered frame, can assume one of the following
6073 @item interlace_type @emph{(video only)}
6074 the frame interlace type, can assume one of the following values:
6077 the frame is progressive (not interlaced)
6079 the frame is top-field-first
6081 the frame is bottom-field-first
6084 @item consumed_sample_n @emph{(audio only)}
6085 the number of selected samples before the current frame
6087 @item samples_n @emph{(audio only)}
6088 the number of samples in the current frame
6090 @item sample_rate @emph{(audio only)}
6091 the input sample rate
6094 1 if the filtered frame is a key-frame, 0 otherwise
6097 the position in the file of the filtered frame, -1 if the information
6098 is not available (e.g. for synthetic video)
6100 @item scene @emph{(video only)}
6101 value between 0 and 1 to indicate a new scene; a low value reflects a low
6102 probability for the current frame to introduce a new scene, while a higher
6103 value means the current frame is more likely to be one (see the example below)
6107 The default value of the select expression is "1".
6109 @subsection Examples
6113 Select all frames in input:
6118 The example above is the same as:
6130 Select only I-frames:
6132 select='eq(pict_type\,I)'
6136 Select one frame every 100:
6138 select='not(mod(n\,100))'
6142 Select only frames contained in the 10-20 time interval:
6144 select='gte(t\,10)*lte(t\,20)'
6148 Select only I frames contained in the 10-20 time interval:
6150 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
6154 Select frames with a minimum distance of 10 seconds:
6156 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
6160 Use aselect to select only audio frames with samples number > 100:
6162 aselect='gt(samples_n\,100)'
6166 Create a mosaic of the first scenes:
6168 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
6171 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
6175 @section asendcmd, sendcmd
6177 Send commands to filters in the filtergraph.
6179 These filters read commands to be sent to other filters in the
6182 @code{asendcmd} must be inserted between two audio filters,
6183 @code{sendcmd} must be inserted between two video filters, but apart
6184 from that they act the same way.
6186 The specification of commands can be provided in the filter arguments
6187 with the @var{commands} option, or in a file specified by the
6188 @var{filename} option.
6190 These filters accept the following options:
6193 Set the commands to be read and sent to the other filters.
6195 Set the filename of the commands to be read and sent to the other
6199 @subsection Commands syntax
6201 A commands description consists of a sequence of interval
6202 specifications, comprising a list of commands to be executed when a
6203 particular event related to that interval occurs. The occurring event
6204 is typically the current frame time entering or leaving a given time
6207 An interval is specified by the following syntax:
6209 @var{START}[-@var{END}] @var{COMMANDS};
6212 The time interval is specified by the @var{START} and @var{END} times.
6213 @var{END} is optional and defaults to the maximum time.
6215 The current frame time is considered within the specified interval if
6216 it is included in the interval [@var{START}, @var{END}), that is when
6217 the time is greater or equal to @var{START} and is lesser than
6220 @var{COMMANDS} consists of a sequence of one or more command
6221 specifications, separated by ",", relating to that interval. The
6222 syntax of a command specification is given by:
6224 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
6227 @var{FLAGS} is optional and specifies the type of events relating to
6228 the time interval which enable sending the specified command, and must
6229 be a non-null sequence of identifier flags separated by "+" or "|" and
6230 enclosed between "[" and "]".
6232 The following flags are recognized:
6235 The command is sent when the current frame timestamp enters the
6236 specified interval. In other words, the command is sent when the
6237 previous frame timestamp was not in the given interval, and the
6241 The command is sent when the current frame timestamp leaves the
6242 specified interval. In other words, the command is sent when the
6243 previous frame timestamp was in the given interval, and the
6247 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
6250 @var{TARGET} specifies the target of the command, usually the name of
6251 the filter class or a specific filter instance name.
6253 @var{COMMAND} specifies the name of the command for the target filter.
6255 @var{ARG} is optional and specifies the optional list of argument for
6256 the given @var{COMMAND}.
6258 Between one interval specification and another, whitespaces, or
6259 sequences of characters starting with @code{#} until the end of line,
6260 are ignored and can be used to annotate comments.
6262 A simplified BNF description of the commands specification syntax
6265 @var{COMMAND_FLAG} ::= "enter" | "leave"
6266 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
6267 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
6268 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
6269 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
6270 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
6273 @subsection Examples
6277 Specify audio tempo change at second 4:
6279 asendcmd=c='4.0 atempo tempo 1.5',atempo
6283 Specify a list of drawtext and hue commands in a file.
6285 # show text in the interval 5-10
6286 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
6287 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
6289 # desaturate the image in the interval 15-20
6290 15.0-20.0 [enter] hue reinit s=0,
6291 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
6292 [leave] hue reinit s=1,
6293 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
6295 # apply an exponential saturation fade-out effect, starting from time 25
6296 25 [enter] hue s=exp(t-25)
6299 A filtergraph allowing to read and process the above command list
6300 stored in a file @file{test.cmd}, can be specified with:
6302 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
6307 @section asetpts, setpts
6309 Change the PTS (presentation timestamp) of the input frames.
6311 @code{asetpts} works on audio frames, @code{setpts} on video frames.
6313 Accept in input an expression evaluated through the eval API, which
6314 can contain the following constants:
6318 frame rate, only defined for constant frame-rate video
6321 the presentation timestamp in input
6324 the count of the input frame, starting from 0.
6326 @item NB_CONSUMED_SAMPLES
6327 the number of consumed samples, not including the current frame (only
6331 the number of samples in the current frame (only audio)
6337 the PTS of the first frame
6340 the time in seconds of the first frame
6343 tell if the current frame is interlaced
6346 the time in seconds of the current frame
6352 original position in the file of the frame, or undefined if undefined
6353 for the current frame
6359 previous input time in seconds
6365 previous output time in seconds
6368 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
6372 wallclock (RTC) time at the start of the movie in microseconds
6375 @subsection Examples
6379 Start counting PTS from zero
6385 Apply fast motion effect:
6391 Apply slow motion effect:
6397 Set fixed rate of 25 frames per second:
6403 Set fixed rate 25 fps with some jitter:
6405 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6409 Apply an offset of 10 seconds to the input PTS:
6415 Generate timestamps from a "live source" and rebase onto the current timebase:
6417 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6423 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6424 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6425 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6426 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6428 The filter also has a video output (see the @var{video} option) with a real
6429 time graph to observe the loudness evolution. The graphic contains the logged
6430 message mentioned above, so it is not printed anymore when this option is set,
6431 unless the verbose logging is set. The main graphing area contains the
6432 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6433 the momentary loudness (400 milliseconds).
6435 More information about the Loudness Recommendation EBU R128 on
6436 @url{http://tech.ebu.ch/loudness}.
6438 The filter accepts the following named parameters:
6443 Activate the video output. The audio stream is passed unchanged whether this
6444 option is set or no. The video stream will be the first output stream if
6445 activated. Default is @code{0}.
6448 Set the video size. This option is for video only. Default and minimum
6449 resolution is @code{640x480}.
6452 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6453 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6454 other integer value between this range is allowed.
6458 @subsection Examples
6462 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
6464 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6468 Run an analysis with @command{ffmpeg}:
6470 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6474 @section settb, asettb
6476 Set the timebase to use for the output frames timestamps.
6477 It is mainly useful for testing timebase configuration.
6479 It accepts in input an arithmetic expression representing a rational.
6480 The expression can contain the constants "AVTB" (the
6481 default timebase), "intb" (the input timebase) and "sr" (the sample rate,
6484 The default value for the input is "intb".
6486 @subsection Examples
6490 Set the timebase to 1/25:
6496 Set the timebase to 1/10:
6502 Set the timebase to 1001/1000:
6508 Set the timebase to 2*intb:
6514 Set the default timebase value:
6522 Concatenate audio and video streams, joining them together one after the
6525 The filter works on segments of synchronized video and audio streams. All
6526 segments must have the same number of streams of each type, and that will
6527 also be the number of streams at output.
6529 The filter accepts the following named parameters:
6533 Set the number of segments. Default is 2.
6536 Set the number of output video streams, that is also the number of video
6537 streams in each segment. Default is 1.
6540 Set the number of output audio streams, that is also the number of video
6541 streams in each segment. Default is 0.
6544 Activate unsafe mode: do not fail if segments have a different format.
6548 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
6549 @var{a} audio outputs.
6551 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
6552 segment, in the same order as the outputs, then the inputs for the second
6555 Related streams do not always have exactly the same duration, for various
6556 reasons including codec frame size or sloppy authoring. For that reason,
6557 related synchronized streams (e.g. a video and its audio track) should be
6558 concatenated at once. The concat filter will use the duration of the longest
6559 stream in each segment (except the last one), and if necessary pad shorter
6560 audio streams with silence.
6562 For this filter to work correctly, all segments must start at timestamp 0.
6564 All corresponding streams must have the same parameters in all segments; the
6565 filtering system will automatically select a common pixel format for video
6566 streams, and a common sample format, sample rate and channel layout for
6567 audio streams, but other settings, such as resolution, must be converted
6568 explicitly by the user.
6570 Different frame rates are acceptable but will result in variable frame rate
6571 at output; be sure to configure the output file to handle it.
6573 @subsection Examples
6577 Concatenate an opening, an episode and an ending, all in bilingual version
6578 (video in stream 0, audio in streams 1 and 2):
6580 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
6581 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
6582 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
6583 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
6587 Concatenate two parts, handling audio and video separately, using the
6588 (a)movie sources, and adjusting the resolution:
6590 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
6591 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
6592 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
6594 Note that a desync will happen at the stitch if the audio and video streams
6595 do not have exactly the same duration in the first file.
6599 @section showspectrum
6601 Convert input audio to a video output, representing the audio frequency
6604 The filter accepts the following named parameters:
6607 Specify the video size for the output. Default value is @code{640x512}.
6610 Specify if the spectrum should slide along the window. Default value is
6614 Specify display mode.
6616 It accepts the following values:
6619 all channels are displayed in the same row
6621 all channels are displayed in separate rows
6624 Default value is @samp{combined}.
6627 Specify display color mode.
6629 It accepts the following values:
6632 each channel is displayed in a separate color
6634 each channel is is displayed using the same color scheme
6637 Default value is @samp{channel}.
6640 Specify scale used for calculating intensity color values.
6642 It accepts the following values:
6647 square root, default
6654 Default value is @samp{sqrt}.
6657 Set saturation modifier for displayed colors. Negative values provide
6658 alternative color scheme. @code{0} is no saturation at all.
6659 Saturation must be in [-10.0, 10.0] range.
6660 Default value is @code{1}.
6663 The usage is very similar to the showwaves filter; see the examples in that
6666 @subsection Examples
6670 Large window with logarithmic color scaling:
6672 showspectrum=s=1280x480:scale=log
6676 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
6678 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
6679 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
6685 Convert input audio to a video output, representing the samples waves.
6687 The filter accepts the following named parameters:
6692 Available values are:
6695 Draw a point for each sample.
6698 Draw a vertical line for each sample.
6701 Default value is @code{point}.
6704 Set the number of samples which are printed on the same column. A
6705 larger value will decrease the frame rate. Must be a positive
6706 integer. This option can be set only if the value for @var{rate}
6707 is not explicitly specified.
6710 Set the (approximate) output frame rate. This is done by setting the
6711 option @var{n}. Default value is "25".
6714 Specify the video size for the output. Default value is "600x240".
6717 @subsection Examples
6721 Output the input file audio and the corresponding video representation
6724 amovie=a.mp3,asplit[out0],showwaves[out1]
6728 Create a synthetic signal and show it with showwaves, forcing a
6729 framerate of 30 frames per second:
6731 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
6735 @c man end MULTIMEDIA FILTERS
6737 @chapter Multimedia Sources
6738 @c man begin MULTIMEDIA SOURCES
6740 Below is a description of the currently available multimedia sources.
6744 This is the same as @ref{movie} source, except it selects an audio
6750 Read audio and/or video stream(s) from a movie container.
6752 It accepts the syntax: @var{movie_name}[:@var{options}] where
6753 @var{movie_name} is the name of the resource to read (not necessarily
6754 a file but also a device or a stream accessed through some protocol),
6755 and @var{options} is an optional sequence of @var{key}=@var{value}
6756 pairs, separated by ":".
6758 The description of the accepted options follows.
6762 @item format_name, f
6763 Specifies the format assumed for the movie to read, and can be either
6764 the name of a container or an input device. If not specified the
6765 format is guessed from @var{movie_name} or by probing.
6767 @item seek_point, sp
6768 Specifies the seek point in seconds, the frames will be output
6769 starting from this seek point, the parameter is evaluated with
6770 @code{av_strtod} so the numerical value may be suffixed by an IS
6771 postfix. Default value is "0".
6774 Specifies the streams to read. Several streams can be specified,
6775 separated by "+". The source will then have as many outputs, in the
6776 same order. The syntax is explained in the ``Stream specifiers''
6777 section in the ffmpeg manual. Two special names, "dv" and "da" specify
6778 respectively the default (best suited) video and audio stream. Default
6779 is "dv", or "da" if the filter is called as "amovie".
6781 @item stream_index, si
6782 Specifies the index of the video stream to read. If the value is -1,
6783 the best suited video stream will be automatically selected. Default
6784 value is "-1". Deprecated. If the filter is called "amovie", it will select
6785 audio instead of video.
6788 Specifies how many times to read the stream in sequence.
6789 If the value is less than 1, the stream will be read again and again.
6790 Default value is "1".
6792 Note that when the movie is looped the source timestamps are not
6793 changed, so it will generate non monotonically increasing timestamps.
6796 This filter allows to overlay a second video on top of main input of
6797 a filtergraph as shown in this graph:
6799 input -----------> deltapts0 --> overlay --> output
6802 movie --> scale--> deltapts1 -------+
6805 @subsection Examples
6809 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
6810 on top of the input labelled as "in":
6812 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
6813 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
6817 Read from a video4linux2 device, and overlay it on top of the input
6820 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
6821 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
6825 Read the first video stream and the audio stream with id 0x81 from
6826 dvd.vob; the video is connected to the pad named "video" and the audio is
6827 connected to the pad named "audio":
6829 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
6833 @c man end MULTIMEDIA SOURCES