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 filtergraph. 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 filtergraph 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
668 Set output format constraints for the input audio. The framework will
669 negotiate the most appropriate format to minimize conversions.
671 The filter accepts the following named parameters:
675 A comma-separated list of requested sample formats.
678 A comma-separated list of requested sample rates.
680 @item channel_layouts
681 A comma-separated list of requested channel layouts.
685 If a parameter is omitted, all values are allowed.
687 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
689 aformat='sample_fmts=u8,s16:channel_layouts=stereo'
694 Merge two or more audio streams into a single multi-channel stream.
696 The filter accepts the following named options:
701 Set the number of inputs. Default is 2.
705 If the channel layouts of the inputs are disjoint, and therefore compatible,
706 the channel layout of the output will be set accordingly and the channels
707 will be reordered as necessary. If the channel layouts of the inputs are not
708 disjoint, the output will have all the channels of the first input then all
709 the channels of the second input, in that order, and the channel layout of
710 the output will be the default value corresponding to the total number of
713 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
714 is FC+BL+BR, then the output will be in 5.1, with the channels in the
715 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
716 first input, b1 is the first channel of the second input).
718 On the other hand, if both input are in stereo, the output channels will be
719 in the default order: a1, a2, b1, b2, and the channel layout will be
720 arbitrarily set to 4.0, which may or may not be the expected value.
722 All inputs must have the same sample rate, and format.
724 If inputs do not have the same duration, the output will stop with the
731 Merge two mono files into a stereo stream:
733 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
740 amovie=input.mkv:si=0 [a0];
741 amovie=input.mkv:si=1 [a1];
742 amovie=input.mkv:si=2 [a2];
743 amovie=input.mkv:si=3 [a3];
744 amovie=input.mkv:si=4 [a4];
745 amovie=input.mkv:si=5 [a5];
746 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
752 Mixes multiple audio inputs into a single output.
756 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
758 will mix 3 input audio streams to a single output with the same duration as the
759 first input and a dropout transition time of 3 seconds.
761 The filter accepts the following named parameters:
765 Number of inputs. If unspecified, it defaults to 2.
768 How to determine the end-of-stream.
772 Duration of longest input. (default)
775 Duration of shortest input.
778 Duration of first input.
782 @item dropout_transition
783 Transition time, in seconds, for volume renormalization when an input
784 stream ends. The default value is 2 seconds.
790 Pass the audio source unchanged to the output.
794 Pad the end of a audio stream with silence, this can be used together with
795 -shortest to extend audio streams to the same length as the video stream.
800 Resample the input audio to the specified parameters, using the
801 libswresample library. If none are specified then the filter will
802 automatically convert between its input and output.
804 This filter is also able to stretch/squeeze the audio data to make it match
805 the timestamps or to inject silence / cut out audio to make it match the
806 timestamps, do a combination of both or do neither.
808 The filter accepts the syntax
809 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
810 expresses a sample rate and @var{resampler_options} is a list of
811 @var{key}=@var{value} pairs, separated by ":". See the
812 ffmpeg-resampler manual for the complete list of supported options.
818 Resample the input audio to 44100Hz:
824 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
825 samples per second compensation:
831 @section asetnsamples
833 Set the number of samples per each output audio frame.
835 The last output packet may contain a different number of samples, as
836 the filter will flush all the remaining samples when the input audio
839 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
844 @item nb_out_samples, n
845 Set the number of frames per each output audio frame. The number is
846 intended as the number of samples @emph{per each channel}.
847 Default value is 1024.
850 If set to 1, the filter will pad the last audio frame with zeroes, so
851 that the last frame will contain the same number of samples as the
852 previous ones. Default value is 1.
855 For example, to set the number of per-frame samples to 1234 and
856 disable padding for the last frame, use:
858 asetnsamples=n=1234:p=0
863 Show a line containing various information for each input audio frame.
864 The input audio is not modified.
866 The shown line contains a sequence of key/value pairs of the form
867 @var{key}:@var{value}.
869 A description of each shown parameter follows:
873 sequential number of the input frame, starting from 0
876 Presentation timestamp of the input frame, in time base units; the time base
877 depends on the filter input pad, and is usually 1/@var{sample_rate}.
880 presentation timestamp of the input frame in seconds
883 position of the frame in the input stream, -1 if this information in
884 unavailable and/or meaningless (for example in case of synthetic audio)
893 sample rate for the audio frame
896 number of samples (per channel) in the frame
899 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
900 the data is treated as if all the planes were concatenated.
902 @item plane_checksums
903 A list of Adler-32 checksums for each data plane.
908 Split input audio into several identical outputs.
910 The filter accepts a single parameter which specifies the number of outputs. If
911 unspecified, it defaults to 2.
915 [in] asplit [out0][out1]
918 will create two separate outputs from the same input.
920 To create 3 or more outputs, you need to specify the number of
923 [in] asplit=3 [out0][out1][out2]
927 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
929 will create 5 copies of the input audio.
934 Forward two audio streams and control the order the buffers are forwarded.
936 The argument to the filter is an expression deciding which stream should be
937 forwarded next: if the result is negative, the first stream is forwarded; if
938 the result is positive or zero, the second stream is forwarded. It can use
939 the following variables:
943 number of buffers forwarded so far on each stream
945 number of samples forwarded so far on each stream
947 current timestamp of each stream
950 The default value is @code{t1-t2}, which means to always forward the stream
951 that has a smaller timestamp.
953 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
954 input, while avoiding too much of a desynchronization:
956 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
957 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
965 The filter accepts exactly one parameter, the audio tempo. If not
966 specified then the filter will assume nominal 1.0 tempo. Tempo must
967 be in the [0.5, 2.0] range.
973 Slow down audio to 80% tempo:
979 To speed up audio to 125% tempo:
987 Make audio easier to listen to on headphones.
989 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
990 so that when listened to on headphones the stereo image is moved from
991 inside your head (standard for headphones) to outside and in front of
992 the listener (standard for speakers).
998 Mix channels with specific gain levels. The filter accepts the output
999 channel layout followed by a set of channels definitions.
1001 This filter is also designed to remap efficiently the channels of an audio
1004 The filter accepts parameters of the form:
1005 "@var{l}:@var{outdef}:@var{outdef}:..."
1009 output channel layout or number of channels
1012 output channel specification, of the form:
1013 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1016 output channel to define, either a channel name (FL, FR, etc.) or a channel
1017 number (c0, c1, etc.)
1020 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1023 input channel to use, see out_name for details; it is not possible to mix
1024 named and numbered input channels
1027 If the `=' in a channel specification is replaced by `<', then the gains for
1028 that specification will be renormalized so that the total is 1, thus
1029 avoiding clipping noise.
1031 @subsection Mixing examples
1033 For example, if you want to down-mix from stereo to mono, but with a bigger
1034 factor for the left channel:
1036 pan=1:c0=0.9*c0+0.1*c1
1039 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1040 7-channels surround:
1042 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1045 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1046 that should be preferred (see "-ac" option) unless you have very specific
1049 @subsection Remapping examples
1051 The channel remapping will be effective if, and only if:
1054 @item gain coefficients are zeroes or ones,
1055 @item only one input per channel output,
1058 If all these conditions are satisfied, the filter will notify the user ("Pure
1059 channel mapping detected"), and use an optimized and lossless method to do the
1062 For example, if you have a 5.1 source and want a stereo audio stream by
1063 dropping the extra channels:
1065 pan="stereo: c0=FL : c1=FR"
1068 Given the same source, you can also switch front left and front right channels
1069 and keep the input channel layout:
1071 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1074 If the input is a stereo audio stream, you can mute the front left channel (and
1075 still keep the stereo channel layout) with:
1080 Still with a stereo audio stream input, you can copy the right channel in both
1081 front left and right:
1083 pan="stereo: c0=FR : c1=FR"
1086 @section silencedetect
1088 Detect silence in an audio stream.
1090 This filter logs a message when it detects that the input audio volume is less
1091 or equal to a noise tolerance value for a duration greater or equal to the
1092 minimum detected noise duration.
1094 The printed times and duration are expressed in seconds.
1098 Set silence duration until notification (default is 2 seconds).
1101 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1102 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1105 @subsection Examples
1109 Detect 5 seconds of silence with -50dB noise tolerance:
1111 silencedetect=n=-50dB:d=5
1115 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1116 tolerance in @file{silence.mp3}:
1118 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
1123 Synchronize audio data with timestamps by squeezing/stretching it and/or
1124 dropping samples/adding silence when needed.
1126 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1128 The filter accepts the following named parameters:
1132 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1133 by default. When disabled, time gaps are covered with silence.
1136 Minimum difference between timestamps and audio data (in seconds) to trigger
1137 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1138 this filter, try setting this parameter to 0.
1141 Maximum compensation in samples per second. Relevant only with compensate=1.
1145 Assume the first pts should be this value. The time base is 1 / sample rate.
1146 This allows for padding/trimming at the start of stream. By default, no
1147 assumption is made about the first frame's expected pts, so no padding or
1148 trimming is done. For example, this could be set to 0 to pad the beginning with
1149 silence if an audio stream starts after the video stream or to trim any samples
1150 with a negative pts due to encoder delay.
1154 @section channelsplit
1155 Split each channel in input audio stream into a separate output stream.
1157 This filter accepts the following named parameters:
1159 @item channel_layout
1160 Channel layout of the input stream. Default is "stereo".
1163 For example, assuming a stereo input MP3 file
1165 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1167 will create an output Matroska file with two audio streams, one containing only
1168 the left channel and the other the right channel.
1170 To split a 5.1 WAV file into per-channel files
1172 ffmpeg -i in.wav -filter_complex
1173 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1174 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1175 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1180 Remap input channels to new locations.
1182 This filter accepts the following named parameters:
1184 @item channel_layout
1185 Channel layout of the output stream.
1188 Map channels from input to output. The argument is a comma-separated list of
1189 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1190 @var{in_channel} form. @var{in_channel} can be either the name of the input
1191 channel (e.g. FL for front left) or its index in the input channel layout.
1192 @var{out_channel} is the name of the output channel or its index in the output
1193 channel layout. If @var{out_channel} is not given then it is implicitly an
1194 index, starting with zero and increasing by one for each mapping.
1197 If no mapping is present, the filter will implicitly map input channels to
1198 output channels preserving index.
1200 For example, assuming a 5.1+downmix input MOV file
1202 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
1204 will create an output WAV file tagged as stereo from the downmix channels of
1207 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1209 ffmpeg -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
1213 Join multiple input streams into one multi-channel stream.
1215 The filter accepts the following named parameters:
1219 Number of input streams. Defaults to 2.
1221 @item channel_layout
1222 Desired output channel layout. Defaults to stereo.
1225 Map channels from inputs to output. The argument is a comma-separated list of
1226 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1227 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1228 can be either the name of the input channel (e.g. FL for front left) or its
1229 index in the specified input stream. @var{out_channel} is the name of the output
1233 The filter will attempt to guess the mappings when those are not specified
1234 explicitly. It does so by first trying to find an unused matching input channel
1235 and if that fails it picks the first unused input channel.
1237 E.g. to join 3 inputs (with properly set channel layouts)
1239 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1242 To build a 5.1 output from 6 single-channel streams:
1244 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1245 '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'
1250 Convert the audio sample format, sample rate and channel layout. This filter is
1251 not meant to be used directly.
1255 Adjust the input audio volume.
1257 The filter accepts the following named parameters. If the key of the
1258 first options is omitted, the arguments are interpreted according to
1259 the following syntax:
1261 volume=@var{volume}:@var{precision}
1267 Expresses how the audio volume will be increased or decreased.
1269 Output values are clipped to the maximum value.
1271 The output audio volume is given by the relation:
1273 @var{output_volume} = @var{volume} * @var{input_volume}
1276 Default value for @var{volume} is 1.0.
1279 Set the mathematical precision.
1281 This determines which input sample formats will be allowed, which affects the
1282 precision of the volume scaling.
1286 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1288 32-bit floating-point; limits input sample format to FLT. (default)
1290 64-bit floating-point; limits input sample format to DBL.
1294 @subsection Examples
1298 Halve the input audio volume:
1302 volume=volume=-6.0206dB
1305 In all the above example the named key for @option{volume} can be
1306 omitted, for example like in:
1312 Increase input audio power by 6 decibels using fixed-point precision:
1314 volume=volume=6dB:precision=fixed
1318 @section volumedetect
1320 Detect the volume of the input video.
1322 The filter has no parameters. The input is not modified. Statistics about
1323 the volume will be printed in the log when the input stream end is reached.
1325 In particular it will show the mean volume (root mean square), maximum
1326 volume (on a per-sample basis), and the beginning of an histogram of the
1327 registered volume values (from the maximum value to a cumulated 1/1000 of
1330 All volumes are in decibels relative to the maximum PCM value.
1332 @subsection Examples
1334 Here is an excerpt of the output:
1336 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1337 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1338 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1339 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1340 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1341 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1342 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1343 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1344 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1350 The mean square energy is approximately -27 dB, or 10^-2.7.
1352 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1354 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1357 In other words, raising the volume by +4 dB does not cause any clipping,
1358 raising it by +5 dB causes clipping for 6 samples, etc.
1360 @c man end AUDIO FILTERS
1362 @chapter Audio Sources
1363 @c man begin AUDIO SOURCES
1365 Below is a description of the currently available audio sources.
1369 Buffer audio frames, and make them available to the filter chain.
1371 This source is mainly intended for a programmatic use, in particular
1372 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1374 It accepts the following mandatory parameters:
1375 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
1380 The sample rate of the incoming audio buffers.
1383 The sample format of the incoming audio buffers.
1384 Either a sample format name or its corresponging integer representation from
1385 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1387 @item channel_layout
1388 The channel layout of the incoming audio buffers.
1389 Either a channel layout name from channel_layout_map in
1390 @file{libavutil/channel_layout.c} or its corresponding integer representation
1391 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1394 The number of channels of the incoming audio buffers.
1395 If both @var{channels} and @var{channel_layout} are specified, then they
1400 @subsection Examples
1403 abuffer=44100:s16p:stereo
1406 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1407 Since the sample format with name "s16p" corresponds to the number
1408 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1416 Generate an audio signal specified by an expression.
1418 This source accepts in input one or more expressions (one for each
1419 channel), which are evaluated and used to generate a corresponding
1422 It accepts the syntax: @var{exprs}[::@var{options}].
1423 @var{exprs} is a list of expressions separated by ":", one for each
1424 separate channel. In case the @var{channel_layout} is not
1425 specified, the selected channel layout depends on the number of
1426 provided expressions.
1428 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1431 The description of the accepted options follows.
1435 @item channel_layout, c
1436 Set the channel layout. The number of channels in the specified layout
1437 must be equal to the number of specified expressions.
1440 Set the minimum duration of the sourced audio. See the function
1441 @code{av_parse_time()} for the accepted format.
1442 Note that the resulting duration may be greater than the specified
1443 duration, as the generated audio is always cut at the end of a
1446 If not specified, or the expressed duration is negative, the audio is
1447 supposed to be generated forever.
1450 Set the number of samples per channel per each output frame,
1453 @item sample_rate, s
1454 Specify the sample rate, default to 44100.
1457 Each expression in @var{exprs} can contain the following constants:
1461 number of the evaluated sample, starting from 0
1464 time of the evaluated sample expressed in seconds, starting from 0
1471 @subsection Examples
1481 Generate a sin signal with frequency of 440 Hz, set sample rate to
1484 aevalsrc="sin(440*2*PI*t)::s=8000"
1488 Generate a two channels signal, specify the channel layout (Front
1489 Center + Back Center) explicitly:
1491 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1495 Generate white noise:
1497 aevalsrc="-2+random(0)"
1501 Generate an amplitude modulated signal:
1503 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1507 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1509 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1516 Null audio source, return unprocessed audio frames. It is mainly useful
1517 as a template and to be employed in analysis / debugging tools, or as
1518 the source for filters which ignore the input data (for example the sox
1521 It accepts an optional sequence of @var{key}=@var{value} pairs,
1524 The description of the accepted options follows.
1528 @item sample_rate, s
1529 Specify the sample rate, and defaults to 44100.
1531 @item channel_layout, cl
1533 Specify the channel layout, and can be either an integer or a string
1534 representing a channel layout. The default value of @var{channel_layout}
1537 Check the channel_layout_map definition in
1538 @file{libavutil/channel_layout.c} for the mapping between strings and
1539 channel layout values.
1542 Set the number of samples per requested frames.
1546 @subsection Examples
1550 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1552 anullsrc=r=48000:cl=4
1556 Do the same operation with a more obvious syntax:
1558 anullsrc=r=48000:cl=mono
1563 Buffer audio frames, and make them available to the filter chain.
1565 This source is not intended to be part of user-supplied graph descriptions but
1566 for insertion by calling programs through the interface defined in
1567 @file{libavfilter/buffersrc.h}.
1569 It accepts the following named parameters:
1573 Timebase which will be used for timestamps of submitted frames. It must be
1574 either a floating-point number or in @var{numerator}/@var{denominator} form.
1580 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1582 @item channel_layout
1583 Channel layout of the audio data, in the form that can be accepted by
1584 @code{av_get_channel_layout()}.
1587 All the parameters need to be explicitly defined.
1591 Synthesize a voice utterance using the libflite library.
1593 To enable compilation of this filter you need to configure FFmpeg with
1594 @code{--enable-libflite}.
1596 Note that the flite library is not thread-safe.
1598 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1601 The description of the accepted parameters follows.
1606 If set to 1, list the names of the available voices and exit
1607 immediately. Default value is 0.
1610 Set the maximum number of samples per frame. Default value is 512.
1613 Set the filename containing the text to speak.
1616 Set the text to speak.
1619 Set the voice to use for the speech synthesis. Default value is
1620 @code{kal}. See also the @var{list_voices} option.
1623 @subsection Examples
1627 Read from file @file{speech.txt}, and synthetize the text using the
1628 standard flite voice:
1630 flite=textfile=speech.txt
1634 Read the specified text selecting the @code{slt} voice:
1636 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1640 Input text to ffmpeg:
1642 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1646 Make @file{ffplay} speak the specified text, using @code{flite} and
1647 the @code{lavfi} device:
1649 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1653 For more information about libflite, check:
1654 @url{http://www.speech.cs.cmu.edu/flite/}
1658 Generate an audio signal made of a sine wave with amplitude 1/8.
1660 The audio signal is bit-exact.
1662 It accepts a list of options in the form of @var{key}=@var{value} pairs
1663 separated by ":". If the option name is omitted, the first option is the
1664 frequency and the second option is the beep factor.
1666 The supported options are:
1671 Set the carrier frequency. Default is 440 Hz.
1673 @item beep_factor, b
1674 Enable a periodic beep every second with frequency @var{beep_factor} times
1675 the carrier frequency. Default is 0, meaning the beep is disabled.
1677 @item sample_rate, s
1678 Specify the sample rate, default is 44100.
1681 Specify the duration of the generated audio stream.
1683 @item samples_per_frame
1684 Set the number of samples per output frame, default is 1024.
1687 @subsection Examples
1692 Generate a simple 440 Hz sine wave:
1698 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
1702 sine=frequency=220:beep_factor=4:duration=5
1707 @c man end AUDIO SOURCES
1709 @chapter Audio Sinks
1710 @c man begin AUDIO SINKS
1712 Below is a description of the currently available audio sinks.
1714 @section abuffersink
1716 Buffer audio frames, and make them available to the end of filter chain.
1718 This sink is mainly intended for programmatic use, in particular
1719 through the interface defined in @file{libavfilter/buffersink.h}.
1721 It requires a pointer to an AVABufferSinkContext structure, which
1722 defines the incoming buffers' formats, to be passed as the opaque
1723 parameter to @code{avfilter_init_filter} for initialization.
1727 Null audio sink, do absolutely nothing with the input audio. It is
1728 mainly useful as a template and to be employed in analysis / debugging
1731 @section abuffersink
1732 This sink is intended for programmatic use. Frames that arrive on this sink can
1733 be retrieved by the calling program using the interface defined in
1734 @file{libavfilter/buffersink.h}.
1736 This filter accepts no parameters.
1738 @c man end AUDIO SINKS
1740 @chapter Video Filters
1741 @c man begin VIDEO FILTERS
1743 When you configure your FFmpeg build, you can disable any of the
1744 existing filters using @code{--disable-filters}.
1745 The configure output will show the video filters included in your
1748 Below is a description of the currently available video filters.
1750 @section alphaextract
1752 Extract the alpha component from the input as a grayscale video. This
1753 is especially useful with the @var{alphamerge} filter.
1757 Add or replace the alpha component of the primary input with the
1758 grayscale value of a second input. This is intended for use with
1759 @var{alphaextract} to allow the transmission or storage of frame
1760 sequences that have alpha in a format that doesn't support an alpha
1763 For example, to reconstruct full frames from a normal YUV-encoded video
1764 and a separate video created with @var{alphaextract}, you might use:
1766 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1769 Since this filter is designed for reconstruction, it operates on frame
1770 sequences without considering timestamps, and terminates when either
1771 input reaches end of stream. This will cause problems if your encoding
1772 pipeline drops frames. If you're trying to apply an image as an
1773 overlay to a video stream, consider the @var{overlay} filter instead.
1777 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1778 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1779 Substation Alpha) subtitles files.
1783 Compute the bounding box for the non-black pixels in the input frame
1786 This filter computes the bounding box containing all the pixels with a
1787 luminance value greater than the minimum allowed value.
1788 The parameters describing the bounding box are printed on the filter
1791 @section blackdetect
1793 Detect video intervals that are (almost) completely black. Can be
1794 useful to detect chapter transitions, commercials, or invalid
1795 recordings. Output lines contains the time for the start, end and
1796 duration of the detected black interval expressed in seconds.
1798 In order to display the output lines, you need to set the loglevel at
1799 least to the AV_LOG_INFO value.
1801 This filter accepts a list of options in the form of
1802 @var{key}=@var{value} pairs separated by ":". A description of the
1803 accepted options follows.
1806 @item black_min_duration, d
1807 Set the minimum detected black duration expressed in seconds. It must
1808 be a non-negative floating point number.
1810 Default value is 2.0.
1812 @item picture_black_ratio_th, pic_th
1813 Set the threshold for considering a picture "black".
1814 Express the minimum value for the ratio:
1816 @var{nb_black_pixels} / @var{nb_pixels}
1819 for which a picture is considered black.
1820 Default value is 0.98.
1822 @item pixel_black_th, pix_th
1823 Set the threshold for considering a pixel "black".
1825 The threshold expresses the maximum pixel luminance value for which a
1826 pixel is considered "black". The provided value is scaled according to
1827 the following equation:
1829 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1832 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1833 the input video format, the range is [0-255] for YUV full-range
1834 formats and [16-235] for YUV non full-range formats.
1836 Default value is 0.10.
1839 The following example sets the maximum pixel threshold to the minimum
1840 value, and detects only black intervals of 2 or more seconds:
1842 blackdetect=d=2:pix_th=0.00
1847 Detect frames that are (almost) completely black. Can be useful to
1848 detect chapter transitions or commercials. Output lines consist of
1849 the frame number of the detected frame, the percentage of blackness,
1850 the position in the file if known or -1 and the timestamp in seconds.
1852 In order to display the output lines, you need to set the loglevel at
1853 least to the AV_LOG_INFO value.
1855 The filter accepts parameters as a list of @var{key}=@var{value}
1856 pairs, separated by ":". If the key of the first options is omitted,
1857 the arguments are interpreted according to the syntax
1858 blackframe[=@var{amount}[:@var{threshold}]].
1860 A description of the accepted options follows.
1864 Set the percentage of pixels that have to be below the
1865 threshold to enable black detection. Default value is 98.
1868 Set the threshold below which a pixel value is considered
1869 black. Default value is 32.
1874 Blend two video frames into each other.
1876 It takes two input streams and outputs one stream, the first input is the
1877 "top" layer and second input is "bottom" layer.
1878 Output terminates when shortest input terminates.
1880 This filter accepts a list of options in the form of @var{key}=@var{value}
1881 pairs separated by ":". A description of the accepted options follows.
1889 Set blend mode for specific pixel component or all pixel components in case
1890 of @var{all_mode}. Default value is @code{normal}.
1892 Available values for component modes are:
1925 Set blend opacity for specific pixel component or all pixel components in case
1926 of @var{all_opacity}. Only used in combination with pixel component blend modes.
1933 Set blend expression for specific pixel component or all pixel components in case
1934 of @var{all_expr}. Note that related mode options will be ignored if those are set.
1936 The expressions can use the following variables:
1940 The sequential number of the filtered frame, starting from @code{0}.
1944 the coordinates of the current sample
1948 the width and height of currently filtered plane
1952 Width and height scale depending on the currently filtered plane. It is the
1953 ratio between the corresponding luma plane number of pixels and the current
1954 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
1955 @code{0.5,0.5} for chroma planes.
1958 Time of the current frame, expressed in seconds.
1961 Value of pixel component at current location for first video frame (top layer).
1964 Value of pixel component at current location for second video frame (bottom layer).
1968 @subsection Examples
1972 Apply transition from bottom layer to top layer in first 10 seconds:
1974 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
1978 Apply 1x1 checkerboard effect:
1980 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
1986 Apply boxblur algorithm to the input video.
1988 The filter accepts parameters as a list of @var{key}=@var{value}
1989 pairs, separated by ":". If the key of the first options is omitted,
1990 the arguments are interpreted according to the syntax
1991 @option{luma_radius}:@option{luma_power}:@option{chroma_radius}:@option{chroma_power}:@option{alpha_radius}:@option{alpha_power}.
1993 A description of the accepted options follows.
1996 @item luma_radius, lr
1997 @item chroma_radius, cr
1998 @item alpha_radius, ar
1999 Set an expression for the box radius in pixels used for blurring the
2000 corresponding input plane.
2002 The radius value must be a non-negative number, and must not be
2003 greater than the value of the expression @code{min(w,h)/2} for the
2004 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2007 Default value for @option{luma_radius} is "2". If not specified,
2008 @option{chroma_radius} and @option{alpha_radius} default to the
2009 corresponding value set for @option{luma_radius}.
2011 The expressions can contain the following constants:
2014 the input width and height in pixels
2017 the input chroma image width and height in pixels
2020 horizontal and vertical chroma subsample values. For example for the
2021 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2024 @item luma_power, lp
2025 @item chroma_power, cp
2026 @item alpha_power, ap
2027 Specify how many times the boxblur filter is applied to the
2028 corresponding plane.
2030 Default value for @option{luma_power} is 2. If not specified,
2031 @option{chroma_power} and @option{alpha_power} default to the
2032 corresponding value set for @option{luma_power}.
2034 A value of 0 will disable the effect.
2037 @subsection Examples
2041 Apply a boxblur filter with luma, chroma, and alpha radius
2048 Set luma radius to 2, alpha and chroma radius to 0:
2050 boxblur=2:1:cr=0:ar=0
2054 Set luma and chroma radius to a fraction of the video dimension:
2056 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
2060 @section colormatrix
2062 Convert color matrix.
2064 The filter accepts parameters as a list of @var{key}=@var{value}
2065 pairs, separated by ":". If the key of the first options is omitted,
2066 the arguments are interpreted according to the syntax
2067 @var{src}:@var{dst}.
2069 A description of the accepted options follows:
2073 Specify the source and destination color matrix. Both values must be
2076 The accepted values are:
2092 For example to convert from BT.601 to SMPTE-240M, use the command:
2094 colormatrix=bt601:smpte240m
2099 Copy the input source unchanged to the output. Mainly useful for
2104 Crop the input video.
2106 This filter accepts a list of @var{key}=@var{value} pairs as argument,
2107 separated by ':'. If the key of the first options is omitted, the
2108 arguments are interpreted according to the syntax
2109 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
2111 A description of the accepted options follows:
2114 Set the crop area width. It defaults to @code{iw}.
2115 This expression is evaluated only once during the filter
2119 Set the crop area height. It defaults to @code{ih}.
2120 This expression is evaluated only once during the filter
2124 Set the expression for the x top-left coordinate of the cropped area.
2125 It defaults to @code{(in_w-out_w)/2}.
2126 This expression is evaluated per-frame.
2129 Set the expression for the y top-left coordinate of the cropped area.
2130 It defaults to @code{(in_h-out_h)/2}.
2131 This expression is evaluated per-frame.
2134 If set to 1 will force the output display aspect ratio
2135 to be the same of the input, by changing the output sample aspect
2136 ratio. It defaults to 0.
2139 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2140 expressions containing the following constants:
2144 the computed values for @var{x} and @var{y}. They are evaluated for
2148 the input width and height
2151 same as @var{in_w} and @var{in_h}
2154 the output (cropped) width and height
2157 same as @var{out_w} and @var{out_h}
2160 same as @var{iw} / @var{ih}
2163 input sample aspect ratio
2166 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2169 horizontal and vertical chroma subsample values. For example for the
2170 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2173 the number of input frame, starting from 0
2176 timestamp expressed in seconds, NAN if the input timestamp is unknown
2180 The expression for @var{out_w} may depend on the value of @var{out_h},
2181 and the expression for @var{out_h} may depend on @var{out_w}, but they
2182 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2183 evaluated after @var{out_w} and @var{out_h}.
2185 The @var{x} and @var{y} parameters specify the expressions for the
2186 position of the top-left corner of the output (non-cropped) area. They
2187 are evaluated for each frame. If the evaluated value is not valid, it
2188 is approximated to the nearest valid value.
2190 The expression for @var{x} may depend on @var{y}, and the expression
2191 for @var{y} may depend on @var{x}.
2193 @subsection Examples
2197 Crop area with size 100x100 at position (12,34).
2202 Using named options, the example above becomes:
2204 crop=w=100:h=100:x=12:y=34
2208 Crop the central input area with size 100x100:
2214 Crop the central input area with size 2/3 of the input video:
2216 crop=2/3*in_w:2/3*in_h
2220 Crop the input video central square:
2226 Delimit the rectangle with the top-left corner placed at position
2227 100:100 and the right-bottom corner corresponding to the right-bottom
2228 corner of the input image:
2230 crop=in_w-100:in_h-100:100:100
2234 Crop 10 pixels from the left and right borders, and 20 pixels from
2235 the top and bottom borders
2237 crop=in_w-2*10:in_h-2*20
2241 Keep only the bottom right quarter of the input image:
2243 crop=in_w/2:in_h/2:in_w/2:in_h/2
2247 Crop height for getting Greek harmony:
2249 crop=in_w:1/PHI*in_w
2253 Appply trembling effect:
2255 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)
2259 Apply erratic camera effect depending on timestamp:
2261 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)"
2265 Set x depending on the value of y:
2267 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2273 Auto-detect crop size.
2275 Calculate necessary cropping parameters and prints the recommended
2276 parameters through the logging system. The detected dimensions
2277 correspond to the non-black area of the input video.
2279 The filter accepts parameters as a list of @var{key}=@var{value}
2280 pairs, separated by ":". If the key of the first options is omitted,
2281 the arguments are interpreted according to the syntax
2282 [@option{limit}[:@option{round}[:@option{reset}]]].
2284 A description of the accepted options follows.
2289 Set higher black value threshold, which can be optionally specified
2290 from nothing (0) to everything (255). An intensity value greater
2291 to the set value is considered non-black. Default value is 24.
2294 Set the value for which the width/height should be divisible by. The
2295 offset is automatically adjusted to center the video. Use 2 to get
2296 only even dimensions (needed for 4:2:2 video). 16 is best when
2297 encoding to most video codecs. Default value is 16.
2300 Set the counter that determines after how many frames cropdetect will
2301 reset the previously detected largest video area and start over to
2302 detect the current optimal crop area. Default value is 0.
2304 This can be useful when channel logos distort the video area. 0
2305 indicates never reset and return the largest area encountered during
2311 Apply color adjustments using curves.
2313 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
2314 component (red, green and blue) has its values defined by @var{N} key points
2315 tied from each other using a smooth curve. The x-axis represents the pixel
2316 values from the input frame, and the y-axis the new pixel values to be set for
2319 By default, a component curve is defined by the two points @var{(0;0)} and
2320 @var{(1;1)}. This creates a straight line where each original pixel value is
2321 "adjusted" to its own value, which means no change to the image.
2323 The filter allows you to redefine these two points and add some more. A new
2324 curve (using a natural cubic spline interpolation) will be define to pass
2325 smoothly through all these new coordinates. The new defined points needs to be
2326 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
2327 be in the @var{[0;1]} interval. If the computed curves happened to go outside
2328 the vector spaces, the values will be clipped accordingly.
2330 If there is no key point defined in @code{x=0}, the filter will automatically
2331 insert a @var{(0;0)} point. In the same way, if there is no key point defined
2332 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
2334 The filter accepts parameters as a list of @var{key}=@var{value}
2335 pairs, separated by ":". If the key of the first options is omitted,
2336 the arguments are interpreted according to the syntax
2337 curves[=@var{preset}].
2339 A description of the accepted parameters follows.
2343 Set the key points for the red component.
2345 Set the key points for the green component.
2347 Set the key points for the blue component.
2349 Select one of the available color presets. This option can not be used in
2350 addition to the @option{r}, @option{g}, @option{b} parameters.
2351 Available presets are:
2353 @item color_negative
2356 @item increase_contrast
2358 @item linear_contrast
2359 @item medium_contrast
2361 @item strong_contrast
2367 To avoid some filtergraph syntax conflicts, each key points list need to be
2368 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
2370 @subsection Examples
2374 Increase slightly the middle level of blue:
2376 curves=blue='0.5/0.58'
2382 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
2384 Here we obtain the following coordinates for each components:
2387 @code{(0;0.11) (0.42;0.51) (1;0.95)}
2389 @code{(0;0) (0.50;0.48) (1;1)}
2391 @code{(0;0.22) (0.49;0.44) (1;0.80)}
2395 The previous example can also be achieved with the associated built-in preset:
2397 curves=preset=vintage
2409 Drop frames that do not differ greatly from the previous frame in
2410 order to reduce frame rate.
2412 The main use of this filter is for very-low-bitrate encoding
2413 (e.g. streaming over dialup modem), but it could in theory be used for
2414 fixing movies that were inverse-telecined incorrectly.
2416 The filter accepts parameters as a list of @var{key}=@var{value}
2417 pairs, separated by ":". If the key of the first options is omitted,
2418 the arguments are interpreted according to the syntax:
2419 @option{max}:@option{hi}:@option{lo}:@option{frac}.
2421 A description of the accepted options follows.
2425 Set the maximum number of consecutive frames which can be dropped (if
2426 positive), or the minimum interval between dropped frames (if
2427 negative). If the value is 0, the frame is dropped unregarding the
2428 number of previous sequentially dropped frames.
2435 Set the dropping threshold values.
2437 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
2438 represent actual pixel value differences, so a threshold of 64
2439 corresponds to 1 unit of difference for each pixel, or the same spread
2440 out differently over the block.
2442 A frame is a candidate for dropping if no 8x8 blocks differ by more
2443 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
2444 meaning the whole image) differ by more than a threshold of @option{lo}.
2446 Default value for @option{hi} is 64*12, default value for @option{lo} is
2447 64*5, and default value for @option{frac} is 0.33.
2452 Suppress a TV station logo by a simple interpolation of the surrounding
2453 pixels. Just set a rectangle covering the logo and watch it disappear
2454 (and sometimes something even uglier appear - your mileage may vary).
2456 The filter accepts parameters as a string of the form
2457 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
2458 @var{key}=@var{value} pairs, separated by ":".
2460 The description of the accepted parameters follows.
2465 Specify the top left corner coordinates of the logo. They must be
2469 Specify the width and height of the logo to clear. They must be
2473 Specify the thickness of the fuzzy edge of the rectangle (added to
2474 @var{w} and @var{h}). The default value is 4.
2477 When set to 1, a green rectangle is drawn on the screen to simplify
2478 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2479 @var{band} is set to 4. The default value is 0.
2483 @subsection Examples
2487 Set a rectangle covering the area with top left corner coordinates 0,0
2488 and size 100x77, setting a band of size 10:
2490 delogo=0:0:100:77:10
2494 As the previous example, but use named options:
2496 delogo=x=0:y=0:w=100:h=77:band=10
2503 Attempt to fix small changes in horizontal and/or vertical shift. This
2504 filter helps remove camera shake from hand-holding a camera, bumping a
2505 tripod, moving on a vehicle, etc.
2507 The filter accepts parameters as a list of @var{key}=@var{value}
2508 pairs, separated by ":". If the key of the first options is omitted,
2509 the arguments are interpreted according to the syntax
2510 @var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}:@var{opencl}.
2512 A description of the accepted parameters follows.
2517 Specify a rectangular area where to limit the search for motion
2519 If desired the search for motion vectors can be limited to a
2520 rectangular area of the frame defined by its top left corner, width
2521 and height. These parameters have the same meaning as the drawbox
2522 filter which can be used to visualise the position of the bounding
2525 This is useful when simultaneous movement of subjects within the frame
2526 might be confused for camera motion by the motion vector search.
2528 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2529 then the full frame is used. This allows later options to be set
2530 without specifying the bounding box for the motion vector search.
2532 Default - search the whole frame.
2535 Specify the maximum extent of movement in x and y directions in the
2536 range 0-64 pixels. Default 16.
2539 Specify how to generate pixels to fill blanks at the edge of the
2540 frame. Available values are:
2543 Fill zeroes at blank locations
2545 Original image at blank locations
2547 Extruded edge value at blank locations
2549 Mirrored edge at blank locations
2551 Default value is @samp{mirror}.
2554 Specify the blocksize to use for motion search. Range 4-128 pixels,
2558 Specify the contrast threshold for blocks. Only blocks with more than
2559 the specified contrast (difference between darkest and lightest
2560 pixels) will be considered. Range 1-255, default 125.
2563 Specify the search strategy. Available values are:
2566 Set exhaustive search
2568 Set less exhaustive search.
2570 Default value is @samp{exhaustive}.
2573 If set then a detailed log of the motion search is written to the
2577 If set to 1, specify using OpenCL capabilities, only available if
2578 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
2584 Draw a colored box on the input image.
2586 The filter accepts parameters as a list of @var{key}=@var{value}
2587 pairs, separated by ":". If the key of the first options is omitted,
2588 the arguments are interpreted according to the syntax
2589 @option{x}:@option{y}:@option{width}:@option{height}:@option{color}:@option{thickness}.
2591 A description of the accepted options follows.
2595 Specify the top left corner coordinates of the box. Default to 0.
2599 Specify the width and height of the box, if 0 they are interpreted as
2600 the input width and height. Default to 0.
2603 Specify the color of the box to write, it can be the name of a color
2604 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2605 value @code{invert} is used, the box edge color is the same as the
2606 video with inverted luma.
2609 Set the thickness of the box edge. Default value is @code{4}.
2612 @subsection Examples
2616 Draw a black box around the edge of the input image:
2622 Draw a box with color red and an opacity of 50%:
2624 drawbox=10:20:200:60:red@@0.5
2627 The previous example can be specified as:
2629 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2633 Fill the box with pink color:
2635 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2642 Draw text string or text from specified file on top of video using the
2643 libfreetype library.
2645 To enable compilation of this filter you need to configure FFmpeg with
2646 @code{--enable-libfreetype}.
2650 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
2653 The description of the accepted parameters follows.
2658 Used to draw a box around text using background color.
2659 Value should be either 1 (enable) or 0 (disable).
2660 The default value of @var{box} is 0.
2663 The color to be used for drawing box around text.
2664 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2665 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2666 The default value of @var{boxcolor} is "white".
2669 Set an expression which specifies if the text should be drawn. If the
2670 expression evaluates to 0, the text is not drawn. This is useful for
2671 specifying that the text should be drawn only when specific conditions
2674 Default value is "1".
2676 See below for the list of accepted constants and functions.
2679 Select how the @var{text} is expanded. Can be either @code{none},
2680 @code{strftime} (deprecated) or
2681 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2685 If true, check and fix text coords to avoid clipping.
2688 The color to be used for drawing fonts.
2689 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2690 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2691 The default value of @var{fontcolor} is "black".
2694 The font file to be used for drawing text. Path must be included.
2695 This parameter is mandatory.
2698 The font size to be used for drawing text.
2699 The default value of @var{fontsize} is 16.
2702 Flags to be used for loading the fonts.
2704 The flags map the corresponding flags supported by libfreetype, and are
2705 a combination of the following values:
2712 @item vertical_layout
2713 @item force_autohint
2716 @item ignore_global_advance_width
2718 @item ignore_transform
2725 Default value is "render".
2727 For more information consult the documentation for the FT_LOAD_*
2731 The color to be used for drawing a shadow behind the drawn text. It
2732 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2733 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2734 The default value of @var{shadowcolor} is "black".
2736 @item shadowx, shadowy
2737 The x and y offsets for the text shadow position with respect to the
2738 position of the text. They can be either positive or negative
2739 values. Default value for both is "0".
2742 The size in number of spaces to use for rendering the tab.
2746 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2747 format. It can be used with or without text parameter. @var{timecode_rate}
2748 option must be specified.
2750 @item timecode_rate, rate, r
2751 Set the timecode frame rate (timecode only).
2754 The text string to be drawn. The text must be a sequence of UTF-8
2756 This parameter is mandatory if no file is specified with the parameter
2760 A text file containing text to be drawn. The text must be a sequence
2761 of UTF-8 encoded characters.
2763 This parameter is mandatory if no text string is specified with the
2764 parameter @var{text}.
2766 If both @var{text} and @var{textfile} are specified, an error is thrown.
2769 If set to 1, the @var{textfile} will be reloaded before each frame.
2770 Be sure to update it atomically, or it may be read partially, or even fail.
2773 The expressions which specify the offsets where text will be drawn
2774 within the video frame. They are relative to the top/left border of the
2777 The default value of @var{x} and @var{y} is "0".
2779 See below for the list of accepted constants and functions.
2782 The parameters for @var{x} and @var{y} are expressions containing the
2783 following constants and functions:
2787 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2790 horizontal and vertical chroma subsample values. For example for the
2791 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2794 the height of each text line
2802 @item max_glyph_a, ascent
2803 the maximum distance from the baseline to the highest/upper grid
2804 coordinate used to place a glyph outline point, for all the rendered
2806 It is a positive value, due to the grid's orientation with the Y axis
2809 @item max_glyph_d, descent
2810 the maximum distance from the baseline to the lowest grid coordinate
2811 used to place a glyph outline point, for all the rendered glyphs.
2812 This is a negative value, due to the grid's orientation, with the Y axis
2816 maximum glyph height, that is the maximum height for all the glyphs
2817 contained in the rendered text, it is equivalent to @var{ascent} -
2821 maximum glyph width, that is the maximum width for all the glyphs
2822 contained in the rendered text
2825 the number of input frame, starting from 0
2827 @item rand(min, max)
2828 return a random number included between @var{min} and @var{max}
2831 input sample aspect ratio
2834 timestamp expressed in seconds, NAN if the input timestamp is unknown
2837 the height of the rendered text
2840 the width of the rendered text
2843 the x and y offset coordinates where the text is drawn.
2845 These parameters allow the @var{x} and @var{y} expressions to refer
2846 each other, so you can for example specify @code{y=x/dar}.
2849 If libavfilter was built with @code{--enable-fontconfig}, then
2850 @option{fontfile} can be a fontconfig pattern or omitted.
2852 @anchor{drawtext_expansion}
2853 @subsection Text expansion
2855 If @option{expansion} is set to @code{strftime},
2856 the filter recognizes strftime() sequences in the provided text and
2857 expands them accordingly. Check the documentation of strftime(). This
2858 feature is deprecated.
2860 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2862 If @option{expansion} is set to @code{normal} (which is the default),
2863 the following expansion mechanism is used.
2865 The backslash character '\', followed by any character, always expands to
2866 the second character.
2868 Sequence of the form @code{%@{...@}} are expanded. The text between the
2869 braces is a function name, possibly followed by arguments separated by ':'.
2870 If the arguments contain special characters or delimiters (':' or '@}'),
2871 they should be escaped.
2873 Note that they probably must also be escaped as the value for the
2874 @option{text} option in the filter argument string and as the filter
2875 argument in the filtergraph description, and possibly also for the shell,
2876 that makes up to four levels of escaping; using a text file avoids these
2879 The following functions are available:
2884 The expression evaluation result.
2886 It must take one argument specifying the expression to be evaluated,
2887 which accepts the same constants and functions as the @var{x} and
2888 @var{y} values. Note that not all constants should be used, for
2889 example the text size is not known when evaluating the expression, so
2890 the constants @var{text_w} and @var{text_h} will have an undefined
2894 The time at which the filter is running, expressed in UTC.
2895 It can accept an argument: a strftime() format string.
2898 The time at which the filter is running, expressed in the local time zone.
2899 It can accept an argument: a strftime() format string.
2902 The frame number, starting from 0.
2905 The timestamp of the current frame, in seconds, with microsecond accuracy.
2909 @subsection Examples
2913 Draw "Test Text" with font FreeSerif, using the default values for the
2914 optional parameters.
2917 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2921 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2922 and y=50 (counting from the top-left corner of the screen), text is
2923 yellow with a red box around it. Both the text and the box have an
2927 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2928 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2931 Note that the double quotes are not necessary if spaces are not used
2932 within the parameter list.
2935 Show the text at the center of the video frame:
2937 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2941 Show a text line sliding from right to left in the last row of the video
2942 frame. The file @file{LONG_LINE} is assumed to contain a single line
2945 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2949 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2951 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2955 Draw a single green letter "g", at the center of the input video.
2956 The glyph baseline is placed at half screen height.
2958 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2962 Show text for 1 second every 3 seconds:
2964 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2968 Use fontconfig to set the font. Note that the colons need to be escaped.
2970 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2974 Print the date of a real-time encoding (see strftime(3)):
2976 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
2981 For more information about libfreetype, check:
2982 @url{http://www.freetype.org/}.
2984 For more information about fontconfig, check:
2985 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
2989 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
2991 This filter accepts the following optional named parameters:
2995 Set low and high threshold values used by the Canny thresholding
2998 The high threshold selects the "strong" edge pixels, which are then
2999 connected through 8-connectivity with the "weak" edge pixels selected
3000 by the low threshold.
3002 @var{low} and @var{high} threshold values must be choosen in the range
3003 [0,1], and @var{low} should be lesser or equal to @var{high}.
3005 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3011 edgedetect=low=0.1:high=0.4
3016 Apply fade-in/out effect to input video.
3018 The filter accepts parameters as a list of @var{key}=@var{value}
3019 pairs, separated by ":". If the key of the first options is omitted,
3020 the arguments are interpreted according to the syntax
3021 @var{type}:@var{start_frame}:@var{nb_frames}.
3023 A description of the accepted parameters follows.
3027 Specify if the effect type, can be either @code{in} for fade-in, or
3028 @code{out} for a fade-out effect. Default is @code{in}.
3030 @item start_frame, s
3031 Specify the number of the start frame for starting to apply the fade
3032 effect. Default is 0.
3035 Specify the number of frames for which the fade effect has to last. At
3036 the end of the fade-in effect the output video will have the same
3037 intensity as the input video, at the end of the fade-out transition
3038 the output video will be completely black. Default is 25.
3041 If set to 1, fade only alpha channel, if one exists on the input.
3045 @subsection Examples
3049 Fade in first 30 frames of video:
3054 The command above is equivalent to:
3060 Fade out last 45 frames of a 200-frame video:
3066 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
3068 fade=in:0:25, fade=out:975:25
3072 Make first 5 frames black, then fade in from frame 5-24:
3078 Fade in alpha over first 25 frames of video:
3080 fade=in:0:25:alpha=1
3086 Extract a single field from an interlaced image using stride
3087 arithmetic to avoid wasting CPU time. The output frames are marked as
3090 This filter accepts the following named options:
3093 Specify whether to extract the top (if the value is @code{0} or
3094 @code{top}) or the bottom field (if the value is @code{1} or
3098 If the option key is not specified, the first value sets the @var{type}
3099 option. For example:
3111 Transform the field order of the input video.
3113 This filter accepts the named option @option{order} which
3114 specifies the required field order that the input interlaced video
3115 will be transformed to. The option name can be omitted.
3117 The option @option{order} can assume one of the following values:
3120 output bottom field first
3122 output top field first
3125 Default value is @samp{tff}.
3127 Transformation is achieved by shifting the picture content up or down
3128 by one line, and filling the remaining line with appropriate picture content.
3129 This method is consistent with most broadcast field order converters.
3131 If the input video is not flagged as being interlaced, or it is already
3132 flagged as being of the required output field order then this filter does
3133 not alter the incoming video.
3135 This filter is very useful when converting to or from PAL DV material,
3136 which is bottom field first.
3140 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
3145 Buffer input images and send them when they are requested.
3147 This filter is mainly useful when auto-inserted by the libavfilter
3150 The filter does not take parameters.
3155 Convert the input video to one of the specified pixel formats.
3156 Libavfilter will try to pick one that is supported for the input to
3159 The filter accepts a list of pixel format names, separated by ":",
3160 for example "yuv420p:monow:rgb24".
3162 @subsection Examples
3166 Convert the input video to the format @var{yuv420p}
3171 Convert the input video to any of the formats in the list
3173 format=yuv420p:yuv444p:yuv410p
3179 Convert the video to specified constant frame rate by duplicating or dropping
3180 frames as necessary.
3182 This filter accepts the following named parameters:
3186 Desired output frame rate. The default is @code{25}.
3191 Possible values are:
3194 zero round towards 0
3198 round towards -infinity
3200 round towards +infinity
3204 The default is @code{near}.
3208 Alternatively, the options can be specified as a flat string:
3209 @var{fps}[:@var{round}].
3211 See also the @ref{setpts} filter.
3215 Select one frame every N.
3217 This filter accepts in input a string representing a positive
3218 integer. Default argument is @code{1}.
3223 Apply a frei0r effect to the input video.
3225 To enable compilation of this filter you need to install the frei0r
3226 header and configure FFmpeg with @code{--enable-frei0r}.
3228 The filter supports the syntax:
3230 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
3233 @var{filter_name} is the name of the frei0r effect to load. If the
3234 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
3235 is searched in each one of the directories specified by the colon (or
3236 semicolon on Windows platforms) separated list in @env{FREIOR_PATH},
3237 otherwise in the standard frei0r paths, which are in this order:
3238 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3239 @file{/usr/lib/frei0r-1/}.
3241 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
3242 for the frei0r effect.
3244 A frei0r effect parameter can be a boolean (whose values are specified
3245 with "y" and "n"), a double, a color (specified by the syntax
3246 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3247 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3248 description), a position (specified by the syntax @var{X}/@var{Y},
3249 @var{X} and @var{Y} being float numbers) and a string.
3251 The number and kind of parameters depend on the loaded effect. If an
3252 effect parameter is not specified the default value is set.
3254 @subsection Examples
3258 Apply the distort0r effect, set the first two double parameters:
3260 frei0r=distort0r:0.5:0.01
3264 Apply the colordistance effect, take a color as first parameter:
3266 frei0r=colordistance:0.2/0.3/0.4
3267 frei0r=colordistance:violet
3268 frei0r=colordistance:0x112233
3272 Apply the perspective effect, specify the top left and top right image
3275 frei0r=perspective:0.2/0.2:0.8/0.2
3279 For more information see:
3280 @url{http://frei0r.dyne.org}
3284 The filter takes one, two, three or four equations as parameter, separated by ':'.
3285 The first equation is mandatory and applies to the luma plane. The two
3286 following are respectively for chroma blue and chroma red planes.
3288 The filter syntax allows named parameters:
3292 the luminance expression
3294 the chrominance blue expression
3296 the chrominance red expression
3298 the alpha expression
3301 If one of the chrominance expression is not defined, it falls back on the other
3302 one. If no alpha expression is specified it will evaluate to opaque value.
3303 If none of chrominance expressions are
3304 specified, they will evaluate the luminance expression.
3306 The expressions can use the following variables and functions:
3310 The sequential number of the filtered frame, starting from @code{0}.
3314 The coordinates of the current sample.
3318 The width and height of the image.
3322 Width and height scale depending on the currently filtered plane. It is the
3323 ratio between the corresponding luma plane number of pixels and the current
3324 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3325 @code{0.5,0.5} for chroma planes.
3328 Time of the current frame, expressed in seconds.
3331 Return the value of the pixel at location (@var{x},@var{y}) of the current
3335 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3339 Return the value of the pixel at location (@var{x},@var{y}) of the
3340 blue-difference chroma plane. Returns 0 if there is no such plane.
3343 Return the value of the pixel at location (@var{x},@var{y}) of the
3344 red-difference chroma plane. Returns 0 if there is no such plane.
3347 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
3348 plane. Returns 0 if there is no such plane.
3351 For functions, if @var{x} and @var{y} are outside the area, the value will be
3352 automatically clipped to the closer edge.
3354 @subsection Examples
3358 Flip the image horizontally:
3364 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3365 wavelength of 100 pixels:
3367 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3371 Generate a fancy enigmatic moving light:
3373 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
3379 Fix the banding artifacts that are sometimes introduced into nearly flat
3380 regions by truncation to 8bit color depth.
3381 Interpolate the gradients that should go where the bands are, and
3384 This filter is designed for playback only. Do not use it prior to
3385 lossy compression, because compression tends to lose the dither and
3386 bring back the bands.
3388 The filter accepts a list of options in the form of @var{key}=@var{value} pairs
3389 separated by ":". A description of the accepted options follows.
3394 The maximum amount by which the filter will change
3395 any one pixel. Also the threshold for detecting nearly flat
3396 regions. Acceptable values range from @code{0.51} to @code{64}, default value
3400 The neighborhood to fit the gradient to. A larger
3401 radius makes for smoother gradients, but also prevents the filter from
3402 modifying the pixels near detailed regions. Acceptable values are
3403 @code{8-32}, default value is @code{16}.
3407 Alternatively, the options can be specified as a flat string:
3408 @var{strength}[:@var{radius}]
3410 @subsection Examples
3414 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3420 Specify radius, omitting the strength (which will fall-back to the default
3430 Flip the input video horizontally.
3432 For example to horizontally flip the input video with @command{ffmpeg}:
3434 ffmpeg -i in.avi -vf "hflip" out.avi
3438 This filter applies a global color histogram equalization on a
3441 It can be used to correct video that has a compressed range of pixel
3442 intensities. The filter redistributes the pixel intensities to
3443 equalize their distribution across the intensity range. It may be
3444 viewed as an "automatically adjusting contrast filter". This filter is
3445 useful only for correcting degraded or poorly captured source
3448 The filter accepts parameters as a list of @var{key}=@var{value}
3449 pairs, separated by ":". If the key of the first options is omitted,
3450 the arguments are interpreted according to syntax
3451 @var{strength}:@var{intensity}:@var{antibanding}.
3453 This filter accepts the following named options:
3457 Determine the amount of equalization to be applied. As the strength
3458 is reduced, the distribution of pixel intensities more-and-more
3459 approaches that of the input frame. The value must be a float number
3460 in the range [0,1] and defaults to 0.200.
3463 Set the maximum intensity that can generated and scale the output
3464 values appropriately. The strength should be set as desired and then
3465 the intensity can be limited if needed to avoid washing-out. The value
3466 must be a float number in the range [0,1] and defaults to 0.210.
3469 Set the antibanding level. If enabled the filter will randomly vary
3470 the luminance of output pixels by a small amount to avoid banding of
3471 the histogram. Possible values are @code{none}, @code{weak} or
3472 @code{strong}. It defaults to @code{none}.
3477 Compute and draw a color distribution histogram for the input video.
3479 The computed histogram is a representation of distribution of color components
3482 The filter accepts the following named parameters:
3488 It accepts the following values:
3491 standard histogram that display color components distribution in an image.
3492 Displays color graph for each color component. Shows distribution
3493 of the Y, U, V, A or G, B, R components, depending on input format,
3494 in current frame. Bellow each graph is color component scale meter.
3497 chroma values in vectorscope, if brighter more such chroma values are
3498 distributed in an image.
3499 Displays chroma values (U/V color placement) in two dimensional graph
3500 (which is called a vectorscope). It can be used to read of the hue and
3501 saturation of the current frame. At a same time it is a histogram.
3502 The whiter a pixel in the vectorscope, the more pixels of the input frame
3503 correspond to that pixel (that is the more pixels have this chroma value).
3504 The V component is displayed on the horizontal (X) axis, with the leftmost
3505 side being V = 0 and the rightmost side being V = 255.
3506 The U component is displayed on the vertical (Y) axis, with the top
3507 representing U = 0 and the bottom representing U = 255.
3509 The position of a white pixel in the graph corresponds to the chroma value
3510 of a pixel of the input clip. So the graph can be used to read of the
3511 hue (color flavor) and the saturation (the dominance of the hue in the color).
3512 As the hue of a color changes, it moves around the square. At the center of
3513 the square, the saturation is zero, which means that the corresponding pixel
3514 has no color. If you increase the amount of a specific color, while leaving
3515 the other colors unchanged, the saturation increases, and you move towards
3516 the edge of the square.
3519 chroma values in vectorscope, similar as @code{color} but actual chroma values
3523 per row/column color component graph. In row mode graph in the left side represents
3524 color component value 0 and right side represents value = 255. In column mode top
3525 side represents color component value = 0 and bottom side represents value = 255.
3527 Default value is @code{levels}.
3530 Set height of level in @code{levels}. Default value is @code{200}.
3531 Allowed range is [50, 2048].
3534 Set height of color scale in @code{levels}. Default value is @code{12}.
3535 Allowed range is [0, 40].
3538 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3539 of same luminance values across input rows/columns are distributed.
3540 Default value is @code{10}. Allowed range is [1, 255].
3543 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3544 Default is @code{row}.
3547 Set display mode for @code{waveform} and @code{levels}.
3548 It accepts the following values:
3551 Display separate graph for the color components side by side in
3552 @code{row} waveform mode or one below other in @code{column} waveform mode
3553 for @code{waveform} histogram mode. For @code{levels} histogram mode
3554 per color component graphs are placed one bellow other.
3556 This display mode in @code{waveform} histogram mode makes it easy to spot
3557 color casts in the highlights and shadows of an image, by comparing the
3558 contours of the top and the bottom of each waveform.
3559 Since whites, grays, and blacks are characterized by
3560 exactly equal amounts of red, green, and blue, neutral areas of the
3561 picture should display three waveforms of roughly equal width/height.
3562 If not, the correction is easy to make by making adjustments to level the
3566 Presents information that's identical to that in the @code{parade}, except
3567 that the graphs representing color components are superimposed directly
3570 This display mode in @code{waveform} histogram mode can make it easier to spot
3571 the relative differences or similarities in overlapping areas of the color
3572 components that are supposed to be identical, such as neutral whites, grays,
3575 Default is @code{parade}.
3578 @subsection Examples
3583 Calculate and draw histogram:
3585 ffplay -i input -vf histogram
3592 High precision/quality 3d denoise filter. This filter aims to reduce
3593 image noise producing smooth images and making still images really
3594 still. It should enhance compressibility.
3596 It accepts the following optional parameters:
3597 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
3601 a non-negative float number which specifies spatial luma strength,
3604 @item chroma_spatial
3605 a non-negative float number which specifies spatial chroma strength,
3606 defaults to 3.0*@var{luma_spatial}/4.0
3609 a float number which specifies luma temporal strength, defaults to
3610 6.0*@var{luma_spatial}/4.0
3613 a float number which specifies chroma temporal strength, defaults to
3614 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3619 Modify the hue and/or the saturation of the input.
3621 This filter accepts the following optional named options:
3625 Specify the hue angle as a number of degrees. It accepts a float
3626 number or an expression, and defaults to 0.0.
3629 Specify the hue angle as a number of radians. It accepts a float
3630 number or an expression, and defaults to 0.0.
3633 Specify the saturation in the [-10,10] range. It accepts a float number and
3637 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3638 following constants:
3642 frame count of the input frame starting from 0
3645 presentation timestamp of the input frame expressed in time base units
3648 frame rate of the input video, NAN if the input frame rate is unknown
3651 timestamp expressed in seconds, NAN if the input timestamp is unknown
3654 time base of the input video
3657 The options can also be set using the syntax: @var{hue}:@var{saturation}
3659 In this case @var{hue} is expressed in degrees.
3661 @subsection Examples
3665 Set the hue to 90 degrees and the saturation to 1.0:
3671 Same command but expressing the hue in radians:
3677 Same command without named options, hue must be expressed in degrees:
3683 Note that "h:s" syntax does not support expressions for the values of
3684 h and s, so the following example will issue an error:
3690 Rotate hue and make the saturation swing between 0
3691 and 2 over a period of 1 second:
3693 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3697 Apply a 3 seconds saturation fade-in effect starting at 0:
3702 The general fade-in expression can be written as:
3704 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3708 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3710 hue="s=max(0\, min(1\, (8-t)/3))"
3713 The general fade-out expression can be written as:
3715 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3720 @subsection Commands
3722 This filter supports the following command:
3725 Modify the hue and/or the saturation of the input video.
3726 The command accepts the same named options and syntax than when calling the
3727 filter from the command-line.
3729 If a parameter is omitted, it is kept at its current value.
3734 Detect video interlacing type.
3736 This filter tries to detect if the input is interlaced or progressive,
3737 top or bottom field first.
3741 Deinterleave or interleave fields.
3743 This filter allows to process interlaced images fields without
3744 deinterlacing them. Deinterleaving splits the input frame into 2
3745 fields (so called half pictures). Odd lines are moved to the top
3746 half of the output image, even lines to the bottom half.
3747 You can process (filter) them independently and then re-interleave them.
3749 It accepts a list of options in the form of @var{key}=@var{value} pairs
3750 separated by ":". A description of the accepted options follows.
3754 @item chroma_mode, s
3756 Available values for @var{luma_mode}, @var{chroma_mode} and
3757 @var{alpha_mode} are:
3763 @item deinterleave, d
3764 Deinterleave fields, placing one above the other.
3767 Interleave fields. Reverse the effect of deinterleaving.
3769 Default value is @code{none}.
3772 @item chroma_swap, cs
3773 @item alpha_swap, as
3774 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3779 Deinterlace input video by applying Donald Graft's adaptive kernel
3780 deinterling. Work on interlaced parts of a video to produce
3783 This filter accepts parameters as a list of @var{key}=@var{value}
3784 pairs, separated by ":". If the key of the first options is omitted,
3785 the arguments are interpreted according to the following syntax:
3786 @var{thresh}:@var{map}:@var{order}:@var{sharp}:@var{twoway}.
3788 The description of the accepted parameters follows.
3792 Set the threshold which affects the filter's tolerance when
3793 determining if a pixel line must be processed. It must be an integer
3794 in the range [0,255] and defaults to 10. A value of 0 will result in
3795 applying the process on every pixels.
3798 Paint pixels exceeding the threshold value to white if set to 1.
3802 Set the fields order. Swap fields if set to 1, leave fields alone if
3806 Enable additional sharpening if set to 1. Default is 0.
3809 Enable twoway sharpening if set to 1. Default is 0.
3812 @subsection Examples
3816 Apply default values:
3818 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3822 Enable additional sharpening:
3828 Paint processed pixels in white:
3834 @section lut, lutrgb, lutyuv
3836 Compute a look-up table for binding each pixel component input value
3837 to an output value, and apply it to input video.
3839 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3840 to an RGB input video.
3842 These filters accept in input a ":"-separated list of options, which
3843 specify the expressions used for computing the lookup table for the
3844 corresponding pixel component values.
3846 The @var{lut} filter requires either YUV or RGB pixel formats in
3847 input, and accepts the options:
3850 set first pixel component expression
3852 set second pixel component expression
3854 set third pixel component expression
3856 set fourth pixel component expression, corresponds to the alpha component
3859 The exact component associated to each option depends on the format in
3862 The @var{lutrgb} filter requires RGB pixel formats in input, and
3863 accepts the options:
3866 set red component expression
3868 set green component expression
3870 set blue component expression
3872 alpha component expression
3875 The @var{lutyuv} filter requires YUV pixel formats in input, and
3876 accepts the options:
3879 set Y/luminance component expression
3881 set U/Cb component expression
3883 set V/Cr component expression
3885 set alpha component expression
3888 The expressions can contain the following constants and functions:
3892 the input width and height
3895 input value for the pixel component
3898 the input value clipped in the @var{minval}-@var{maxval} range
3901 maximum value for the pixel component
3904 minimum value for the pixel component
3907 the negated value for the pixel component value clipped in the
3908 @var{minval}-@var{maxval} range , it corresponds to the expression
3909 "maxval-clipval+minval"
3912 the computed value in @var{val} clipped in the
3913 @var{minval}-@var{maxval} range
3915 @item gammaval(gamma)
3916 the computed gamma correction value of the pixel component value
3917 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3919 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3923 All expressions default to "val".
3925 @subsection Examples
3931 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3932 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3935 The above is the same as:
3937 lutrgb="r=negval:g=negval:b=negval"
3938 lutyuv="y=negval:u=negval:v=negval"
3948 Remove chroma components, turns the video into a graytone image:
3950 lutyuv="u=128:v=128"
3954 Apply a luma burning effect:
3960 Remove green and blue components:
3966 Set a constant alpha channel value on input:
3968 format=rgba,lutrgb=a="maxval-minval/2"
3972 Correct luminance gamma by a 0.5 factor:
3974 lutyuv=y=gammaval(0.5)
3978 Discard least significant bits of luma:
3980 lutyuv=y='bitand(val, 128+64+32)'
3986 Apply an MPlayer filter to the input video.
3988 This filter provides a wrapper around most of the filters of
3991 This wrapper is considered experimental. Some of the wrapped filters
3992 may not work properly and we may drop support for them, as they will
3993 be implemented natively into FFmpeg. Thus you should avoid
3994 depending on them when writing portable scripts.
3996 The filters accepts the parameters:
3997 @var{filter_name}[:=]@var{filter_params}
3999 @var{filter_name} is the name of a supported MPlayer filter,
4000 @var{filter_params} is a string containing the parameters accepted by
4003 The list of the currently supported filters follows:
4030 The parameter syntax and behavior for the listed filters are the same
4031 of the corresponding MPlayer filters. For detailed instructions check
4032 the "VIDEO FILTERS" section in the MPlayer manual.
4034 @subsection Examples
4038 Adjust gamma, brightness, contrast:
4044 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
4050 This filter accepts an integer in input, if non-zero it negates the
4051 alpha component (if available). The default value in input is 0.
4055 Force libavfilter not to use any of the specified pixel formats for the
4056 input to the next filter.
4058 The filter accepts a list of pixel format names, separated by ":",
4059 for example "yuv420p:monow:rgb24".
4061 @subsection Examples
4065 Force libavfilter to use a format different from @var{yuv420p} for the
4066 input to the vflip filter:
4068 noformat=yuv420p,vflip
4072 Convert the input video to any of the formats not contained in the list:
4074 noformat=yuv420p:yuv444p:yuv410p
4080 Add noise on video input frame.
4082 This filter accepts a list of options in the form of @var{key}=@var{value}
4083 pairs separated by ":". A description of the accepted options follows.
4091 Set noise seed for specific pixel component or all pixel components in case
4092 of @var{all_seed}. Default value is @code{123457}.
4094 @item all_strength, alls
4095 @item c0_strength, c0s
4096 @item c1_strength, c1s
4097 @item c2_strength, c2s
4098 @item c3_strength, c3s
4099 Set noise strength for specific pixel component or all pixel components in case
4100 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
4102 @item all_flags, allf
4107 Set pixel component flags or set flags for all components if @var{all_flags}.
4108 Available values for component flags are:
4111 averaged temporal noise (smoother)
4113 mix random noise with a (semi)regular pattern
4115 higher quality (slightly better looking, slightly slower)
4117 temporal noise (noise pattern changes between frames)
4119 uniform noise (gaussian otherwise)
4123 @subsection Examples
4125 Add temporal and uniform noise to input video:
4127 noise=alls=20:allf=t+u
4132 Pass the video source unchanged to the output.
4136 Apply video transform using libopencv.
4138 To enable this filter install libopencv library and headers and
4139 configure FFmpeg with @code{--enable-libopencv}.
4141 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
4143 @var{filter_name} is the name of the libopencv filter to apply.
4145 @var{filter_params} specifies the parameters to pass to the libopencv
4146 filter. If not specified the default values are assumed.
4148 Refer to the official libopencv documentation for more precise
4150 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
4152 Follows the list of supported libopencv filters.
4157 Dilate an image by using a specific structuring element.
4158 This filter corresponds to the libopencv function @code{cvDilate}.
4160 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
4162 @var{struct_el} represents a structuring element, and has the syntax:
4163 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
4165 @var{cols} and @var{rows} represent the number of columns and rows of
4166 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
4167 point, and @var{shape} the shape for the structuring element, and
4168 can be one of the values "rect", "cross", "ellipse", "custom".
4170 If the value for @var{shape} is "custom", it must be followed by a
4171 string of the form "=@var{filename}". The file with name
4172 @var{filename} is assumed to represent a binary image, with each
4173 printable character corresponding to a bright pixel. When a custom
4174 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
4175 or columns and rows of the read file are assumed instead.
4177 The default value for @var{struct_el} is "3x3+0x0/rect".
4179 @var{nb_iterations} specifies the number of times the transform is
4180 applied to the image, and defaults to 1.
4182 Follow some example:
4184 # use the default values
4187 # dilate using a structuring element with a 5x5 cross, iterate two times
4188 ocv=dilate=5x5+2x2/cross:2
4190 # read the shape from the file diamond.shape, iterate two times
4191 # the file diamond.shape may contain a pattern of characters like this:
4197 # the specified cols and rows are ignored (but not the anchor point coordinates)
4198 ocv=0x0+2x2/custom=diamond.shape:2
4203 Erode an image by using a specific structuring element.
4204 This filter corresponds to the libopencv function @code{cvErode}.
4206 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4207 with the same syntax and semantics as the @ref{dilate} filter.
4211 Smooth the input video.
4213 The filter takes the following parameters:
4214 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
4216 @var{type} is the type of smooth filter to apply, and can be one of
4217 the following values: "blur", "blur_no_scale", "median", "gaussian",
4218 "bilateral". The default value is "gaussian".
4220 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
4221 parameters whose meanings depend on smooth type. @var{param1} and
4222 @var{param2} accept integer positive values or 0, @var{param3} and
4223 @var{param4} accept float values.
4225 The default value for @var{param1} is 3, the default value for the
4226 other parameters is 0.
4228 These parameters correspond to the parameters assigned to the
4229 libopencv function @code{cvSmooth}.
4234 Overlay one video on top of another.
4236 It takes two inputs and one output, the first input is the "main"
4237 video on which the second input is overlayed.
4239 This filter accepts a list of @var{key}=@var{value} pairs as argument,
4240 separated by ":". If the key of the first options is omitted, the
4241 arguments are interpreted according to the syntax @var{x}:@var{y}.
4243 A description of the accepted options follows.
4247 Set the expression for the x and y coordinates of the overlayed video
4248 on the main video. Default value is 0.
4250 The @var{x} and @var{y} expressions can contain the following
4253 @item main_w, main_h
4254 main input width and height
4257 same as @var{main_w} and @var{main_h}
4259 @item overlay_w, overlay_h
4260 overlay input width and height
4263 same as @var{overlay_w} and @var{overlay_h}
4267 Set the format for the output video.
4269 It accepts the following values:
4281 Default value is @samp{yuv420}.
4283 @item rgb @emph{(deprecated)}
4284 If set to 1, force the filter to accept inputs in the RGB
4285 color space. Default value is 0. This option is deprecated, use
4286 @option{format} instead.
4289 If set to 1, force the output to terminate when the shortest input
4290 terminates. Default value is 0.
4293 Be aware that frames are taken from each input video in timestamp
4294 order, hence, if their initial timestamps differ, it is a a good idea
4295 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4296 have them begin in the same zero timestamp, as it does the example for
4297 the @var{movie} filter.
4299 You can chain together more overlays but you should test the
4300 efficiency of such approach.
4302 @subsection Examples
4306 Draw the overlay at 10 pixels from the bottom right corner of the main
4309 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4312 Using named options the example above becomes:
4314 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4318 Insert a transparent PNG logo in the bottom left corner of the input,
4319 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4321 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4325 Insert 2 different transparent PNG logos (second logo on bottom
4326 right corner) using the @command{ffmpeg} tool:
4328 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
4332 Add a transparent color layer on top of the main video, @code{WxH}
4333 must specify the size of the main input to the overlay filter:
4335 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
4339 Play an original video and a filtered version (here with the deshake
4340 filter) side by side using the @command{ffplay} tool:
4342 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4345 The above command is the same as:
4347 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4351 Compose output by putting two input videos side to side:
4353 ffmpeg -i left.avi -i right.avi -filter_complex "
4354 nullsrc=size=200x100 [background];
4355 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4356 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4357 [background][left] overlay=shortest=1 [background+left];
4358 [background+left][right] overlay=shortest=1:x=100 [left+right]
4363 Chain several overlays in cascade:
4365 nullsrc=s=200x200 [bg];
4366 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4367 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4368 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4369 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4370 [in3] null, [mid2] overlay=100:100 [out0]
4377 Add paddings to the input image, and place the original input at the
4378 given coordinates @var{x}, @var{y}.
4380 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
4383 If the key of the first options is omitted, the arguments are
4384 interpreted according to the syntax
4385 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
4387 A description of the accepted options follows.
4392 Specify an expression for the size of the output image with the
4393 paddings added. If the value for @var{width} or @var{height} is 0, the
4394 corresponding input size is used for the output.
4396 The @var{width} expression can reference the value set by the
4397 @var{height} expression, and vice versa.
4399 The default value of @var{width} and @var{height} is 0.
4403 Specify an expression for the offsets where to place the input image
4404 in the padded area with respect to the top/left border of the output
4407 The @var{x} expression can reference the value set by the @var{y}
4408 expression, and vice versa.
4410 The default value of @var{x} and @var{y} is 0.
4413 Specify the color of the padded area, it can be the name of a color
4414 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4416 The default value of @var{color} is "black".
4419 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4420 options are expressions containing the following constants:
4424 the input video width and height
4427 same as @var{in_w} and @var{in_h}
4430 the output width and height, that is the size of the padded area as
4431 specified by the @var{width} and @var{height} expressions
4434 same as @var{out_w} and @var{out_h}
4437 x and y offsets as specified by the @var{x} and @var{y}
4438 expressions, or NAN if not yet specified
4441 same as @var{iw} / @var{ih}
4444 input sample aspect ratio
4447 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4450 horizontal and vertical chroma subsample values. For example for the
4451 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4454 @subsection Examples
4458 Add paddings with color "violet" to the input video. Output video
4459 size is 640x480, the top-left corner of the input video is placed at
4462 pad=640:480:0:40:violet
4465 The example above is equivalent to the following command:
4467 pad=width=640:height=480:x=0:y=40:color=violet
4471 Pad the input to get an output with dimensions increased by 3/2,
4472 and put the input video at the center of the padded area:
4474 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4478 Pad the input to get a squared output with size equal to the maximum
4479 value between the input width and height, and put the input video at
4480 the center of the padded area:
4482 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4486 Pad the input to get a final w/h ratio of 16:9:
4488 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4492 In case of anamorphic video, in order to set the output display aspect
4493 correctly, it is necessary to use @var{sar} in the expression,
4494 according to the relation:
4496 (ih * X / ih) * sar = output_dar
4497 X = output_dar / sar
4500 Thus the previous example needs to be modified to:
4502 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4506 Double output size and put the input video in the bottom-right
4507 corner of the output padded area:
4509 pad="2*iw:2*ih:ow-iw:oh-ih"
4513 @section pixdesctest
4515 Pixel format descriptor test filter, mainly useful for internal
4516 testing. The output video should be equal to the input video.
4520 format=monow, pixdesctest
4523 can be used to test the monowhite pixel format descriptor definition.
4527 Enable the specified chain of postprocessing subfilters using libpostproc. This
4528 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4529 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4530 Each subfilter and some options have a short and a long name that can be used
4531 interchangeably, i.e. dr/dering are the same.
4533 All subfilters share common options to determine their scope:
4537 Honor the quality commands for this subfilter.
4540 Do chrominance filtering, too (default).
4543 Do luminance filtering only (no chrominance).
4546 Do chrominance filtering only (no luminance).
4549 These options can be appended after the subfilter name, separated by a ':'.
4551 Available subfilters are:
4554 @item hb/hdeblock[:difference[:flatness]]
4555 Horizontal deblocking filter
4558 Difference factor where higher values mean more deblocking (default: @code{32}).
4560 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4563 @item vb/vdeblock[:difference[:flatness]]
4564 Vertical deblocking filter
4567 Difference factor where higher values mean more deblocking (default: @code{32}).
4569 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4572 @item ha/hadeblock[:difference[:flatness]]
4573 Accurate horizontal deblocking filter
4576 Difference factor where higher values mean more deblocking (default: @code{32}).
4578 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4581 @item va/vadeblock[:difference[:flatness]]
4582 Accurate vertical deblocking filter
4585 Difference factor where higher values mean more deblocking (default: @code{32}).
4587 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4591 The horizontal and vertical deblocking filters share the difference and
4592 flatness values so you cannot set different horizontal and vertical
4597 Experimental horizontal deblocking filter
4600 Experimental vertical deblocking filter
4605 @item tn/tmpnoise[:threshold1[:threshold2[:threshold3]]], temporal noise reducer
4608 larger -> stronger filtering
4610 larger -> stronger filtering
4612 larger -> stronger filtering
4615 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4618 Stretch luminance to @code{0-255}.
4621 @item lb/linblenddeint
4622 Linear blend deinterlacing filter that deinterlaces the given block by
4623 filtering all lines with a @code{(1 2 1)} filter.
4625 @item li/linipoldeint
4626 Linear interpolating deinterlacing filter that deinterlaces the given block by
4627 linearly interpolating every second line.
4629 @item ci/cubicipoldeint
4630 Cubic interpolating deinterlacing filter deinterlaces the given block by
4631 cubically interpolating every second line.
4633 @item md/mediandeint
4634 Median deinterlacing filter that deinterlaces the given block by applying a
4635 median filter to every second line.
4637 @item fd/ffmpegdeint
4638 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4639 second line with a @code{(-1 4 2 4 -1)} filter.
4642 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4643 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4645 @item fq/forceQuant[:quantizer]
4646 Overrides the quantizer table from the input with the constant quantizer you
4654 Default pp filter combination (@code{hb:a,vb:a,dr:a})
4657 Fast pp filter combination (@code{h1:a,v1:a,dr:a})
4660 High quality pp filter combination (@code{ha:a:128:7,va:a,dr:a})
4663 @subsection Examples
4667 Apply horizontal and vertical deblocking, deringing and automatic
4668 brightness/contrast:
4674 Apply default filters without brightness/contrast correction:
4680 Apply default filters and temporal denoiser:
4682 pp=default/tmpnoise:1:2:3
4686 Apply deblocking on luminance only, and switch vertical deblocking on or off
4687 automatically depending on available CPU time:
4695 Suppress a TV station logo, using an image file to determine which
4696 pixels comprise the logo. It works by filling in the pixels that
4697 comprise the logo with neighboring pixels.
4699 This filter requires one argument which specifies the filter bitmap
4700 file, which can be any image format supported by libavformat. The
4701 width and height of the image file must match those of the video
4702 stream being processed.
4704 Pixels in the provided bitmap image with a value of zero are not
4705 considered part of the logo, non-zero pixels are considered part of
4706 the logo. If you use white (255) for the logo and black (0) for the
4707 rest, you will be safe. For making the filter bitmap, it is
4708 recommended to take a screen capture of a black frame with the logo
4709 visible, and then using a threshold filter followed by the erode
4710 filter once or twice.
4712 If needed, little splotches can be fixed manually. Remember that if
4713 logo pixels are not covered, the filter quality will be much
4714 reduced. Marking too many pixels as part of the logo does not hurt as
4715 much, but it will increase the amount of blurring needed to cover over
4716 the image and will destroy more information than necessary, and extra
4717 pixels will slow things down on a large logo.
4721 Scale (resize) the input video, using the libswscale library.
4723 The scale filter forces the output display aspect ratio to be the same
4724 of the input, by changing the output sample aspect ratio.
4726 This filter accepts a list of named options in the form of
4727 @var{key}=@var{value} pairs separated by ":". If the key for the first
4728 two options is not specified, the assumed keys for the first two
4729 values are @code{w} and @code{h}. If the first option has no key and
4730 can be interpreted like a video size specification, it will be used
4731 to set the video size.
4733 A description of the accepted options follows.
4737 Set the video width expression, default value is @code{iw}. See below
4738 for the list of accepted constants.
4741 Set the video heiht expression, default value is @code{ih}.
4742 See below for the list of accepted constants.
4745 Set the interlacing. It accepts the following values:
4749 force interlaced aware scaling
4752 do not apply interlaced scaling
4755 select interlaced aware scaling depending on whether the source frames
4756 are flagged as interlaced or not
4759 Default value is @code{0}.
4762 Set libswscale scaling flags. If not explictly specified the filter
4763 applies a bilinear scaling algorithm.
4766 Set the video size, the value must be a valid abbreviation or in the
4767 form @var{width}x@var{height}.
4770 The values of the @var{w} and @var{h} options are expressions
4771 containing the following constants:
4775 the input width and height
4778 same as @var{in_w} and @var{in_h}
4781 the output (cropped) width and height
4784 same as @var{out_w} and @var{out_h}
4787 same as @var{iw} / @var{ih}
4790 input sample aspect ratio
4793 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4796 horizontal and vertical chroma subsample values. For example for the
4797 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4800 If the input image format is different from the format requested by
4801 the next filter, the scale filter will convert the input to the
4804 If the value for @var{width} or @var{height} is 0, the respective input
4805 size is used for the output.
4807 If the value for @var{width} or @var{height} is -1, the scale filter will
4808 use, for the respective output size, a value that maintains the aspect
4809 ratio of the input image.
4811 @subsection Examples
4815 Scale the input video to a size of 200x100:
4820 This is equivalent to:
4831 Specify a size abbreviation for the output size:
4836 which can also be written as:
4842 Scale the input to 2x:
4848 The above is the same as:
4854 Scale the input to 2x with forced interlaced scaling:
4856 scale=2*iw:2*ih:interl=1
4860 Scale the input to half size:
4866 Increase the width, and set the height to the same size:
4872 Seek for Greek harmony:
4879 Increase the height, and set the width to 3/2 of the height:
4885 Increase the size, but make the size a multiple of the chroma
4888 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4892 Increase the width to a maximum of 500 pixels, keep the same input
4895 scale='min(500\, iw*3/2):-1'
4899 @section setdar, setsar
4901 The @code{setdar} filter sets the Display Aspect Ratio for the filter
4904 This is done by changing the specified Sample (aka Pixel) Aspect
4905 Ratio, according to the following equation:
4907 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
4910 Keep in mind that the @code{setdar} filter does not modify the pixel
4911 dimensions of the video frame. Also the display aspect ratio set by
4912 this filter may be changed by later filters in the filterchain,
4913 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
4916 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
4917 the filter output video.
4919 Note that as a consequence of the application of this filter, the
4920 output display aspect ratio will change according to the equation
4923 Keep in mind that the sample aspect ratio set by the @code{setsar}
4924 filter may be changed by later filters in the filterchain, e.g. if
4925 another "setsar" or a "setdar" filter is applied.
4927 The @code{setdar} and @code{setsar} filters accept a string in the
4928 form @var{num}:@var{den} expressing an aspect ratio, or the following
4929 named options, expressed as a sequence of @var{key}=@var{value} pairs,
4934 Set the maximum integer value to use for expressing numerator and
4935 denominator when reducing the expressed aspect ratio to a rational.
4936 Default value is @code{100}.
4939 Set the aspect ratio used by the filter.
4941 The parameter can be a floating point number string, an expression, or
4942 a string of the form @var{num}:@var{den}, where @var{num} and
4943 @var{den} are the numerator and denominator of the aspect ratio. If
4944 the parameter is not specified, it is assumed the value "0".
4945 In case the form "@var{num}:@var{den}" the @code{:} character should
4949 If the keys are omitted in the named options list, the specifed values
4950 are assumed to be @var{ratio} and @var{max} in that order.
4952 For example to change the display aspect ratio to 16:9, specify:
4957 The example above is equivalent to:
4962 To change the sample aspect ratio to 10:11, specify:
4967 To set a display aspect ratio of 16:9, and specify a maximum integer value of
4968 1000 in the aspect ratio reduction, use the command:
4970 setdar=ratio='16:9':max=1000
4975 Force field for the output video frame.
4977 The @code{setfield} filter marks the interlace type field for the
4978 output frames. It does not change the input frame, but only sets the
4979 corresponding property, which affects how the frame is treated by
4980 following filters (e.g. @code{fieldorder} or @code{yadif}).
4982 This filter accepts a single option @option{mode}, which can be
4983 specified either by setting @code{mode=VALUE} or setting the value
4984 alone. Available values are:
4988 Keep the same field property.
4991 Mark the frame as bottom-field-first.
4994 Mark the frame as top-field-first.
4997 Mark the frame as progressive.
5002 Show a line containing various information for each input video frame.
5003 The input video is not modified.
5005 The shown line contains a sequence of key/value pairs of the form
5006 @var{key}:@var{value}.
5008 A description of each shown parameter follows:
5012 sequential number of the input frame, starting from 0
5015 Presentation TimeStamp of the input frame, expressed as a number of
5016 time base units. The time base unit depends on the filter input pad.
5019 Presentation TimeStamp of the input frame, expressed as a number of
5023 position of the frame in the input stream, -1 if this information in
5024 unavailable and/or meaningless (for example in case of synthetic video)
5030 sample aspect ratio of the input frame, expressed in the form
5034 size of the input frame, expressed in the form
5035 @var{width}x@var{height}
5038 interlaced mode ("P" for "progressive", "T" for top field first, "B"
5039 for bottom field first)
5042 1 if the frame is a key frame, 0 otherwise
5045 picture type of the input frame ("I" for an I-frame, "P" for a
5046 P-frame, "B" for a B-frame, "?" for unknown type).
5047 Check also the documentation of the @code{AVPictureType} enum and of
5048 the @code{av_get_picture_type_char} function defined in
5049 @file{libavutil/avutil.h}.
5052 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
5054 @item plane_checksum
5055 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
5056 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
5061 Blur the input video without impacting the outlines.
5063 This filter accepts parameters as a list of @var{key}=@var{value} pairs,
5066 If the key of the first options is omitted, the arguments are
5067 interpreted according to the syntax:
5068 @var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
5070 A description of the accepted options follows.
5073 @item luma_radius, lr
5074 @item chroma_radius, cr
5075 Set the luma/chroma radius. The option value must be a float number in
5076 the range [0.1,5.0] that specifies the variance of the gaussian filter
5077 used to blur the image (slower if larger). Default value is 1.0.
5079 @item luma_strength, ls
5080 @item chroma_strength, cs
5081 Set the luma/chroma strength. The option value must be a float number
5082 in the range [-1.0,1.0] that configures the blurring. A value included
5083 in [0.0,1.0] will blur the image whereas a value included in
5084 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5086 @item luma_threshold, lt
5087 @item chroma_threshold, ct
5088 Set the luma/chroma threshold used as a coefficient to determine
5089 whether a pixel should be blurred or not. The option value must be an
5090 integer in the range [-30,30]. A value of 0 will filter all the image,
5091 a value included in [0,30] will filter flat areas and a value included
5092 in [-30,0] will filter edges. Default value is 0.
5095 If a chroma option is not explicitly set, the corresponding luma value
5100 Convert between different stereoscopic image formats.
5102 This filter accepts the following named options, expressed as a
5103 sequence of @var{key}=@var{value} pairs, separated by ":".
5107 Set stereoscopic image format of input.
5109 Available values for input image formats are:
5112 side by side parallel (left eye left, right eye right)
5115 side by side crosseye (right eye left, left eye right)
5118 side by side parallel with half width resolution
5119 (left eye left, right eye right)
5122 side by side crosseye with half width resolution
5123 (right eye left, left eye right)
5126 above-below (left eye above, right eye below)
5129 above-below (right eye above, left eye below)
5132 above-below with half height resolution
5133 (left eye above, right eye below)
5136 above-below with half height resolution
5137 (right eye above, left eye below)
5139 Default value is @samp{sbsl}.
5143 Set stereoscopic image format of output.
5145 Available values for output image formats are all the input formats as well as:
5148 anaglyph red/blue gray
5149 (red filter on left eye, blue filter on right eye)
5152 anaglyph red/green gray
5153 (red filter on left eye, green filter on right eye)
5156 anaglyph red/cyan gray
5157 (red filter on left eye, cyan filter on right eye)
5160 anaglyph red/cyan half colored
5161 (red filter on left eye, cyan filter on right eye)
5164 anaglyph red/cyan color
5165 (red filter on left eye, cyan filter on right eye)
5168 anaglyph red/cyan color optimized with the least squares projection of dubois
5169 (red filter on left eye, cyan filter on right eye)
5172 anaglyph green/magenta gray
5173 (green filter on left eye, magenta filter on right eye)
5176 anaglyph green/magenta half colored
5177 (green filter on left eye, magenta filter on right eye)
5180 anaglyph green/magenta colored
5181 (green filter on left eye, magenta filter on right eye)
5184 anaglyph green/magenta color optimized with the least squares projection of dubois
5185 (green filter on left eye, magenta filter on right eye)
5188 anaglyph yellow/blue gray
5189 (yellow filter on left eye, blue filter on right eye)
5192 anaglyph yellow/blue half colored
5193 (yellow filter on left eye, blue filter on right eye)
5196 anaglyph yellow/blue colored
5197 (yellow filter on left eye, blue filter on right eye)
5200 anaglyph yellow/blue color optimized with the least squares projection of dubois
5201 (yellow filter on left eye, blue filter on right eye)
5204 interleaved rows (left eye has top row, right eye starts on next row)
5207 interleaved rows (right eye has top row, left eye starts on next row)
5210 mono output (left eye only)
5213 mono output (right eye only)
5216 Default value is @samp{arcd}.
5222 Draw subtitles on top of input video using the libass library.
5224 To enable compilation of this filter you need to configure FFmpeg with
5225 @code{--enable-libass}. This filter also requires a build with libavcodec and
5226 libavformat to convert the passed subtitles file to ASS (Advanced Substation
5227 Alpha) subtitles format.
5229 This filter accepts the following named options, expressed as a
5230 sequence of @var{key}=@var{value} pairs, separated by ":".
5234 Set the filename of the subtitle file to read. It must be specified.
5237 Specify the size of the original video, the video for which the ASS file
5238 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
5239 necessary to correctly scale the fonts if the aspect ratio has been changed.
5242 Set subtitles input character encoding. @code{subtitles} filter only. Only
5243 useful if not UTF-8.
5246 If the first key is not specified, it is assumed that the first value
5247 specifies the @option{filename}.
5249 For example, to render the file @file{sub.srt} on top of the input
5250 video, use the command:
5255 which is equivalent to:
5257 subtitles=filename=sub.srt
5262 Split input video into several identical outputs.
5264 The filter accepts a single parameter which specifies the number of outputs. If
5265 unspecified, it defaults to 2.
5269 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
5271 will create 5 copies of the input video.
5275 [in] split [splitout1][splitout2];
5276 [splitout1] crop=100:100:0:0 [cropout];
5277 [splitout2] pad=200:200:100:100 [padout];
5280 will create two separate outputs from the same input, one cropped and
5285 Scale the input by 2x and smooth using the Super2xSaI (Scale and
5286 Interpolate) pixel art scaling algorithm.
5288 Useful for enlarging pixel art images without reducing sharpness.
5294 Select the most representative frame in a given sequence of consecutive frames.
5296 The filter accepts parameters as a list of @var{key}=@var{value}
5297 pairs, separated by ":". If the key of the first options is omitted,
5298 the arguments are interpreted according to the syntax
5299 thumbnail[=@var{n}].
5303 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
5304 will pick one of them, and then handle the next batch of @var{n} frames until
5305 the end. Default is @code{100}.
5308 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
5309 value will result in a higher memory usage, so a high value is not recommended.
5311 @subsection Examples
5315 Extract one picture each 50 frames:
5321 Complete example of a thumbnail creation with @command{ffmpeg}:
5323 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
5329 Tile several successive frames together.
5331 It accepts a list of options in the form of @var{key}=@var{value} pairs
5332 separated by ":". A description of the accepted options follows.
5337 Set the grid size (i.e. the number of lines and columns) in the form
5341 Set the outer border margin in pixels.
5344 Set the inner border thickness (i.e. the number of pixels between frames). For
5345 more advanced padding options (such as having different values for the edges),
5346 refer to the pad video filter.
5349 Set the maximum number of frames to render in the given area. It must be less
5350 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
5351 the area will be used.
5355 Alternatively, the options can be specified as a flat string:
5357 @var{layout}[:@var{nb_frames}[:@var{margin}[:@var{padding}]]]
5359 For example, produce 8x8 PNG tiles of all keyframes (@option{-skip_frame
5362 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
5364 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
5365 duplicating each output frame to accomodate the originally detected frame
5368 Another example to display @code{5} pictures in an area of @code{3x2} frames,
5369 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
5370 mixed flat and named options:
5372 tile=3x2:nb_frames=5:padding=7:margin=2
5377 Perform various types of temporal field interlacing.
5379 Frames are counted starting from 1, so the first input frame is
5382 This filter accepts options in the form of @var{key}=@var{value} pairs
5384 Alternatively, the @var{mode} option can be specified as a value alone,
5385 optionally followed by a ":" and further ":" separated @var{key}=@var{value}
5388 A description of the accepted options follows.
5393 Specify the mode of the interlacing. This option can also be specified
5394 as a value alone. See below for a list of values for this option.
5396 Available values are:
5400 Move odd frames into the upper field, even into the lower field,
5401 generating a double height frame at half frame rate.
5404 Only output even frames, odd frames are dropped, generating a frame with
5405 unchanged height at half frame rate.
5408 Only output odd frames, even frames are dropped, generating a frame with
5409 unchanged height at half frame rate.
5412 Expand each frame to full height, but pad alternate lines with black,
5413 generating a frame with double height at the same input frame rate.
5415 @item interleave_top, 4
5416 Interleave the upper field from odd frames with the lower field from
5417 even frames, generating a frame with unchanged height at half frame rate.
5419 @item interleave_bottom, 5
5420 Interleave the lower field from odd frames with the upper field from
5421 even frames, generating a frame with unchanged height at half frame rate.
5423 @item interlacex2, 6
5424 Double frame rate with unchanged height. Frames are inserted each
5425 containing the second temporal field from the previous input frame and
5426 the first temporal field from the next input frame. This mode relies on
5427 the top_field_first flag. Useful for interlaced video displays with no
5428 field synchronisation.
5431 Numeric values are deprecated but are accepted for backward
5432 compatibility reasons.
5434 Default mode is @code{merge}.
5437 Specify flags influencing the filter process.
5439 Available value for @var{flags} is:
5442 @item low_pass_filter, vlfp
5443 Enable vertical low-pass filtering in the filter.
5444 Vertical low-pass filtering is required when creating an interlaced
5445 destination from a progressive source which contains high-frequency
5446 vertical detail. Filtering will reduce interlace 'twitter' and Moire
5449 Vertical low-pass filtering can only be enabled for @option{mode}
5450 @var{interleave_top} and @var{interleave_bottom}.
5457 Transpose rows with columns in the input video and optionally flip it.
5459 The filter accepts parameters as a list of @var{key}=@var{value}
5460 pairs, separated by ':'. If the key of the first options is omitted,
5461 the arguments are interpreted according to the syntax
5462 @var{dir}:@var{passthrough}.
5466 Specify the transposition direction. Can assume the following values:
5470 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
5478 Rotate by 90 degrees clockwise, that is:
5486 Rotate by 90 degrees counterclockwise, that is:
5494 Rotate by 90 degrees clockwise and vertically flip, that is:
5502 For values between 4-7, the transposition is only done if the input
5503 video geometry is portrait and not landscape. These values are
5504 deprecated, the @code{passthrough} option should be used instead.
5507 Do not apply the transposition if the input geometry matches the one
5508 specified by the specified value. It accepts the following values:
5511 Always apply transposition.
5513 Preserve portrait geometry (when @var{height} >= @var{width}).
5515 Preserve landscape geometry (when @var{width} >= @var{height}).
5518 Default value is @code{none}.
5521 For example to rotate by 90 degrees clockwise and preserve portrait
5524 transpose=dir=1:passthrough=portrait
5527 The command above can also be specified as:
5529 transpose=1:portrait
5534 Sharpen or blur the input video.
5536 This filter accepts parameters as a list of @var{key}=@var{value} pairs,
5539 If the key of the first options is omitted, the arguments are
5540 interpreted according to the syntax:
5541 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
5543 A description of the accepted options follows.
5546 @item luma_msize_x, lx
5547 @item chroma_msize_x, cx
5548 Set the luma/chroma matrix horizontal size. It must be an odd integer
5549 between 3 and 63, default value is 5.
5551 @item luma_msize_y, ly
5552 @item chroma_msize_y, cy
5553 Set the luma/chroma matrix vertical size. It must be an odd integer
5554 between 3 and 63, default value is 5.
5556 @item luma_amount, la
5557 @item chroma_amount, ca
5558 Set the luma/chroma effect strength. It can be a float number,
5559 reasonable values lay between -1.5 and 1.5.
5561 Negative values will blur the input video, while positive values will
5562 sharpen it, a value of zero will disable the effect.
5564 Default value is 1.0 for @option{luma_amount}, 0.0 for
5565 @option{chroma_amount}.
5568 @subsection Examples
5572 Apply strong luma sharpen effect:
5578 Apply strong blur of both luma and chroma parameters:
5580 unsharp=7:7:-2:7:7:-2
5586 Flip the input video vertically.
5589 ffmpeg -i in.avi -vf "vflip" out.avi
5594 Deinterlace the input video ("yadif" means "yet another deinterlacing
5597 The filter accepts parameters as a list of @var{key}=@var{value}
5598 pairs, separated by ":". If the key of the first options is omitted,
5599 the arguments are interpreted according to syntax
5600 @var{mode}:@var{parity}:@var{deint}.
5602 The description of the accepted parameters follows.
5606 Specify the interlacing mode to adopt. Accept one of the following
5611 output 1 frame for each frame
5613 output 1 frame for each field
5614 @item 2, send_frame_nospatial
5615 like @code{send_frame} but skip spatial interlacing check
5616 @item 3, send_field_nospatial
5617 like @code{send_field} but skip spatial interlacing check
5620 Default value is @code{send_frame}.
5623 Specify the picture field parity assumed for the input interlaced
5624 video. Accept one of the following values:
5628 assume top field first
5630 assume bottom field first
5632 enable automatic detection
5635 Default value is @code{auto}.
5636 If interlacing is unknown or decoder does not export this information,
5637 top field first will be assumed.
5640 Specify which frames to deinterlace. Accept one of the following
5645 deinterlace all frames
5647 only deinterlace frames marked as interlaced
5650 Default value is @code{all}.
5653 @c man end VIDEO FILTERS
5655 @chapter Video Sources
5656 @c man begin VIDEO SOURCES
5658 Below is a description of the currently available video sources.
5662 Buffer video frames, and make them available to the filter chain.
5664 This source is mainly intended for a programmatic use, in particular
5665 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5667 It accepts a list of options in the form of @var{key}=@var{value} pairs
5668 separated by ":". A description of the accepted options follows.
5673 Specify the size (width and height) of the buffered video frames.
5676 A string representing the pixel format of the buffered video frames.
5677 It may be a number corresponding to a pixel format, or a pixel format
5681 Specify the timebase assumed by the timestamps of the buffered frames.
5684 Specify the frame rate expected for the video stream.
5687 Specify the sample aspect ratio assumed by the video frames.
5690 Specify the optional parameters to be used for the scale filter which
5691 is automatically inserted when an input change is detected in the
5692 input size or format.
5697 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
5700 will instruct the source to accept video frames with size 320x240 and
5701 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5702 square pixels (1:1 sample aspect ratio).
5703 Since the pixel format with name "yuv410p" corresponds to the number 6
5704 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5705 this example corresponds to:
5707 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5710 Alternatively, the options can be specified as a flat string, but this
5711 syntax is deprecated:
5713 @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}]
5717 Create a pattern generated by an elementary cellular automaton.
5719 The initial state of the cellular automaton can be defined through the
5720 @option{filename}, and @option{pattern} options. If such options are
5721 not specified an initial state is created randomly.
5723 At each new frame a new row in the video is filled with the result of
5724 the cellular automaton next generation. The behavior when the whole
5725 frame is filled is defined by the @option{scroll} option.
5727 This source accepts a list of options in the form of
5728 @var{key}=@var{value} pairs separated by ":". A description of the
5729 accepted options follows.
5733 Read the initial cellular automaton state, i.e. the starting row, from
5735 In the file, each non-whitespace character is considered an alive
5736 cell, a newline will terminate the row, and further characters in the
5737 file will be ignored.
5740 Read the initial cellular automaton state, i.e. the starting row, from
5741 the specified string.
5743 Each non-whitespace character in the string is considered an alive
5744 cell, a newline will terminate the row, and further characters in the
5745 string will be ignored.
5748 Set the video rate, that is the number of frames generated per second.
5751 @item random_fill_ratio, ratio
5752 Set the random fill ratio for the initial cellular automaton row. It
5753 is a floating point number value ranging from 0 to 1, defaults to
5756 This option is ignored when a file or a pattern is specified.
5758 @item random_seed, seed
5759 Set the seed for filling randomly the initial row, must be an integer
5760 included between 0 and UINT32_MAX. If not specified, or if explicitly
5761 set to -1, the filter will try to use a good random seed on a best
5765 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5766 Default value is 110.
5769 Set the size of the output video.
5771 If @option{filename} or @option{pattern} is specified, the size is set
5772 by default to the width of the specified initial state row, and the
5773 height is set to @var{width} * PHI.
5775 If @option{size} is set, it must contain the width of the specified
5776 pattern string, and the specified pattern will be centered in the
5779 If a filename or a pattern string is not specified, the size value
5780 defaults to "320x518" (used for a randomly generated initial state).
5783 If set to 1, scroll the output upward when all the rows in the output
5784 have been already filled. If set to 0, the new generated row will be
5785 written over the top row just after the bottom row is filled.
5788 @item start_full, full
5789 If set to 1, completely fill the output with generated rows before
5790 outputting the first frame.
5791 This is the default behavior, for disabling set the value to 0.
5794 If set to 1, stitch the left and right row edges together.
5795 This is the default behavior, for disabling set the value to 0.
5798 @subsection Examples
5802 Read the initial state from @file{pattern}, and specify an output of
5805 cellauto=f=pattern:s=200x400
5809 Generate a random initial row with a width of 200 cells, with a fill
5812 cellauto=ratio=2/3:s=200x200
5816 Create a pattern generated by rule 18 starting by a single alive cell
5817 centered on an initial row with width 100:
5819 cellauto=p=@@:s=100x400:full=0:rule=18
5823 Specify a more elaborated initial pattern:
5825 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5832 Generate a Mandelbrot set fractal, and progressively zoom towards the
5833 point specified with @var{start_x} and @var{start_y}.
5835 This source accepts a list of options in the form of
5836 @var{key}=@var{value} pairs separated by ":". A description of the
5837 accepted options follows.
5842 Set the terminal pts value. Default value is 400.
5845 Set the terminal scale value.
5846 Must be a floating point value. Default value is 0.3.
5849 Set the inner coloring mode, that is the algorithm used to draw the
5850 Mandelbrot fractal internal region.
5852 It shall assume one of the following values:
5857 Show time until convergence.
5859 Set color based on point closest to the origin of the iterations.
5864 Default value is @var{mincol}.
5867 Set the bailout value. Default value is 10.0.
5870 Set the maximum of iterations performed by the rendering
5871 algorithm. Default value is 7189.
5874 Set outer coloring mode.
5875 It shall assume one of following values:
5877 @item iteration_count
5878 Set iteration cound mode.
5879 @item normalized_iteration_count
5880 set normalized iteration count mode.
5882 Default value is @var{normalized_iteration_count}.
5885 Set frame rate, expressed as number of frames per second. Default
5889 Set frame size. Default value is "640x480".
5892 Set the initial scale value. Default value is 3.0.
5895 Set the initial x position. Must be a floating point value between
5896 -100 and 100. Default value is -0.743643887037158704752191506114774.
5899 Set the initial y position. Must be a floating point value between
5900 -100 and 100. Default value is -0.131825904205311970493132056385139.
5905 Generate various test patterns, as generated by the MPlayer test filter.
5907 The size of the generated video is fixed, and is 256x256.
5908 This source is useful in particular for testing encoding features.
5910 This source accepts an optional sequence of @var{key}=@var{value} pairs,
5911 separated by ":". The description of the accepted options follows.
5916 Specify the frame rate of the sourced video, as the number of frames
5917 generated per second. It has to be a string in the format
5918 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5919 number or a valid video frame rate abbreviation. The default value is
5923 Set the video duration of the sourced video. The accepted syntax is:
5928 See also the function @code{av_parse_time()}.
5930 If not specified, or the expressed duration is negative, the video is
5931 supposed to be generated forever.
5935 Set the number or the name of the test to perform. Supported tests are:
5950 Default value is "all", which will cycle through the list of all tests.
5953 For example the following:
5958 will generate a "dc_luma" test pattern.
5962 Provide a frei0r source.
5964 To enable compilation of this filter you need to install the frei0r
5965 header and configure FFmpeg with @code{--enable-frei0r}.
5967 The source supports the syntax:
5969 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
5972 @var{size} is the size of the video to generate, may be a string of the
5973 form @var{width}x@var{height} or a frame size abbreviation.
5974 @var{rate} is the rate of the video to generate, may be a string of
5975 the form @var{num}/@var{den} or a frame rate abbreviation.
5976 @var{src_name} is the name to the frei0r source to load. For more
5977 information regarding frei0r and how to set the parameters read the
5978 section @ref{frei0r} in the description of the video filters.
5980 For example, to generate a frei0r partik0l source with size 200x200
5981 and frame rate 10 which is overlayed on the overlay filter main input:
5983 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
5988 Generate a life pattern.
5990 This source is based on a generalization of John Conway's life game.
5992 The sourced input represents a life grid, each pixel represents a cell
5993 which can be in one of two possible states, alive or dead. Every cell
5994 interacts with its eight neighbours, which are the cells that are
5995 horizontally, vertically, or diagonally adjacent.
5997 At each interaction the grid evolves according to the adopted rule,
5998 which specifies the number of neighbor alive cells which will make a
5999 cell stay alive or born. The @option{rule} option allows to specify
6002 This source accepts a list of options in the form of
6003 @var{key}=@var{value} pairs separated by ":". A description of the
6004 accepted options follows.
6008 Set the file from which to read the initial grid state. In the file,
6009 each non-whitespace character is considered an alive cell, and newline
6010 is used to delimit the end of each row.
6012 If this option is not specified, the initial grid is generated
6016 Set the video rate, that is the number of frames generated per second.
6019 @item random_fill_ratio, ratio
6020 Set the random fill ratio for the initial random grid. It is a
6021 floating point number value ranging from 0 to 1, defaults to 1/PHI.
6022 It is ignored when a file is specified.
6024 @item random_seed, seed
6025 Set the seed for filling the initial random grid, must be an integer
6026 included between 0 and UINT32_MAX. If not specified, or if explicitly
6027 set to -1, the filter will try to use a good random seed on a best
6033 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
6034 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
6035 @var{NS} specifies the number of alive neighbor cells which make a
6036 live cell stay alive, and @var{NB} the number of alive neighbor cells
6037 which make a dead cell to become alive (i.e. to "born").
6038 "s" and "b" can be used in place of "S" and "B", respectively.
6040 Alternatively a rule can be specified by an 18-bits integer. The 9
6041 high order bits are used to encode the next cell state if it is alive
6042 for each number of neighbor alive cells, the low order bits specify
6043 the rule for "borning" new cells. Higher order bits encode for an
6044 higher number of neighbor cells.
6045 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
6046 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
6048 Default value is "S23/B3", which is the original Conway's game of life
6049 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
6050 cells, and will born a new cell if there are three alive cells around
6054 Set the size of the output video.
6056 If @option{filename} is specified, the size is set by default to the
6057 same size of the input file. If @option{size} is set, it must contain
6058 the size specified in the input file, and the initial grid defined in
6059 that file is centered in the larger resulting area.
6061 If a filename is not specified, the size value defaults to "320x240"
6062 (used for a randomly generated initial grid).
6065 If set to 1, stitch the left and right grid edges together, and the
6066 top and bottom edges also. Defaults to 1.
6069 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
6070 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
6071 value from 0 to 255.
6074 Set the color of living (or new born) cells.
6077 Set the color of dead cells. If @option{mold} is set, this is the first color
6078 used to represent a dead cell.
6081 Set mold color, for definitely dead and moldy cells.
6084 @subsection Examples
6088 Read a grid from @file{pattern}, and center it on a grid of size
6091 life=f=pattern:s=300x300
6095 Generate a random grid of size 200x200, with a fill ratio of 2/3:
6097 life=ratio=2/3:s=200x200
6101 Specify a custom rule for evolving a randomly generated grid:
6107 Full example with slow death effect (mold) using @command{ffplay}:
6109 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
6113 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
6115 The @code{color} source provides an uniformly colored input.
6117 The @code{nullsrc} source returns unprocessed video frames. It is
6118 mainly useful to be employed in analysis / debugging tools, or as the
6119 source for filters which ignore the input data.
6121 The @code{rgbtestsrc} source generates an RGB test pattern useful for
6122 detecting RGB vs BGR issues. You should see a red, green and blue
6123 stripe from top to bottom.
6125 The @code{smptebars} source generates a color bars pattern, based on
6126 the SMPTE Engineering Guideline EG 1-1990.
6128 The @code{testsrc} source generates a test video pattern, showing a
6129 color pattern, a scrolling gradient and a timestamp. This is mainly
6130 intended for testing purposes.
6132 These sources accept an optional sequence of @var{key}=@var{value} pairs,
6133 separated by ":". The description of the accepted options follows.
6138 Specify the color of the source, only used in the @code{color}
6139 source. It can be the name of a color (case insensitive match) or a
6140 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
6141 default value is "black".
6144 Specify the size of the sourced video, it may be a string of the form
6145 @var{width}x@var{height}, or the name of a size abbreviation. The
6146 default value is "320x240".
6149 Specify the frame rate of the sourced video, as the number of frames
6150 generated per second. It has to be a string in the format
6151 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6152 number or a valid video frame rate abbreviation. The default value is
6156 Set the sample aspect ratio of the sourced video.
6159 Set the video duration of the sourced video. The accepted syntax is:
6161 [-]HH[:MM[:SS[.m...]]]
6164 See also the function @code{av_parse_time()}.
6166 If not specified, or the expressed duration is negative, the video is
6167 supposed to be generated forever.
6170 Set the number of decimals to show in the timestamp, only used in the
6171 @code{testsrc} source.
6173 The displayed timestamp value will correspond to the original
6174 timestamp value multiplied by the power of 10 of the specified
6175 value. Default value is 0.
6178 For example the following:
6180 testsrc=duration=5.3:size=qcif:rate=10
6183 will generate a video with a duration of 5.3 seconds, with size
6184 176x144 and a frame rate of 10 frames per second.
6186 The following graph description will generate a red source
6187 with an opacity of 0.2, with size "qcif" and a frame rate of 10
6190 color=c=red@@0.2:s=qcif:r=10
6193 If the input content is to be ignored, @code{nullsrc} can be used. The
6194 following command generates noise in the luminance plane by employing
6195 the @code{geq} filter:
6197 nullsrc=s=256x256, geq=random(1)*255:128:128
6200 @c man end VIDEO SOURCES
6202 @chapter Video Sinks
6203 @c man begin VIDEO SINKS
6205 Below is a description of the currently available video sinks.
6209 Buffer video frames, and make them available to the end of the filter
6212 This sink is mainly intended for a programmatic use, in particular
6213 through the interface defined in @file{libavfilter/buffersink.h}.
6215 It does not require a string parameter in input, but you need to
6216 specify a pointer to a list of supported pixel formats terminated by
6217 -1 in the opaque parameter provided to @code{avfilter_init_filter}
6218 when initializing this sink.
6222 Null video sink, do absolutely nothing with the input video. It is
6223 mainly useful as a template and to be employed in analysis / debugging
6226 @c man end VIDEO SINKS
6228 @chapter Multimedia Filters
6229 @c man begin MULTIMEDIA FILTERS
6231 Below is a description of the currently available multimedia filters.
6233 @section aperms, perms
6235 Set read/write permissions for the output frames.
6237 These filters are mainly aimed at developers to test direct path in the
6238 following filter in the filtergraph.
6240 The filters accept parameters as a list of @var{key}=@var{value} pairs,
6241 separated by ":". If the key of the first options is omitted, the argument is
6242 assumed to be the @var{mode}.
6244 A description of the accepted parameters follows.
6248 Select the permissions mode.
6250 It accepts the following values:
6253 Do nothing. This is the default.
6255 Set all the output frames read-only.
6257 Set all the output frames directly writable.
6259 Make the frame read-only if writable, and writable if read-only.
6261 Set each output frame read-only or writable randomly.
6265 Set the seed for the @var{random} mode, must be an integer included between
6266 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
6267 @code{-1}, the filter will try to use a good random seed on a best effort
6271 Note: in case of auto-inserted filter between the permission filter and the
6272 following one, the permission might not be received as expected in that
6273 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
6274 perms/aperms filter can avoid this problem.
6277 Add a phasing effect to the input audio.
6279 A phaser filter creates series of peaks and troughs in the frequency spectrum.
6280 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
6282 The filter accepts parameters as a list of @var{key}=@var{value}
6283 pairs, separated by ":".
6285 A description of the accepted parameters follows.
6289 Set input gain. Default is 0.4.
6292 Set output gain. Default is 0.74
6295 Set delay in milliseconds. Default is 3.0.
6298 Set decay. Default is 0.4.
6301 Set modulation speed in Hz. Default is 0.5.
6304 Set modulation type. Default is triangular.
6306 It accepts the following values:
6313 @section aselect, select
6314 Select frames to pass in output.
6316 These filters accept a single option @option{expr} or @option{e}
6317 specifying the select expression, which can be specified either by
6318 specyfing @code{expr=VALUE} or specifying the expression
6321 The select expression is evaluated for each input frame. If the
6322 evaluation result is a non-zero value, the frame is selected and
6323 passed to the output, otherwise it is discarded.
6325 The expression can contain the following constants:
6329 the sequential number of the filtered frame, starting from 0
6332 the sequential number of the selected frame, starting from 0
6334 @item prev_selected_n
6335 the sequential number of the last selected frame, NAN if undefined
6338 timebase of the input timestamps
6341 the PTS (Presentation TimeStamp) of the filtered video frame,
6342 expressed in @var{TB} units, NAN if undefined
6345 the PTS (Presentation TimeStamp) of the filtered video frame,
6346 expressed in seconds, NAN if undefined
6349 the PTS of the previously filtered video frame, NAN if undefined
6351 @item prev_selected_pts
6352 the PTS of the last previously filtered video frame, NAN if undefined
6354 @item prev_selected_t
6355 the PTS of the last previously selected video frame, NAN if undefined
6358 the PTS of the first video frame in the video, NAN if undefined
6361 the time of the first video frame in the video, NAN if undefined
6363 @item pict_type @emph{(video only)}
6364 the type of the filtered frame, can assume one of the following
6376 @item interlace_type @emph{(video only)}
6377 the frame interlace type, can assume one of the following values:
6380 the frame is progressive (not interlaced)
6382 the frame is top-field-first
6384 the frame is bottom-field-first
6387 @item consumed_sample_n @emph{(audio only)}
6388 the number of selected samples before the current frame
6390 @item samples_n @emph{(audio only)}
6391 the number of samples in the current frame
6393 @item sample_rate @emph{(audio only)}
6394 the input sample rate
6397 1 if the filtered frame is a key-frame, 0 otherwise
6400 the position in the file of the filtered frame, -1 if the information
6401 is not available (e.g. for synthetic video)
6403 @item scene @emph{(video only)}
6404 value between 0 and 1 to indicate a new scene; a low value reflects a low
6405 probability for the current frame to introduce a new scene, while a higher
6406 value means the current frame is more likely to be one (see the example below)
6410 The default value of the select expression is "1".
6412 @subsection Examples
6416 Select all frames in input:
6421 The example above is the same as:
6433 Select only I-frames:
6435 select='eq(pict_type\,I)'
6439 Select one frame every 100:
6441 select='not(mod(n\,100))'
6445 Select only frames contained in the 10-20 time interval:
6447 select='gte(t\,10)*lte(t\,20)'
6451 Select only I frames contained in the 10-20 time interval:
6453 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
6457 Select frames with a minimum distance of 10 seconds:
6459 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
6463 Use aselect to select only audio frames with samples number > 100:
6465 aselect='gt(samples_n\,100)'
6469 Create a mosaic of the first scenes:
6471 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
6474 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
6478 @section asendcmd, sendcmd
6480 Send commands to filters in the filtergraph.
6482 These filters read commands to be sent to other filters in the
6485 @code{asendcmd} must be inserted between two audio filters,
6486 @code{sendcmd} must be inserted between two video filters, but apart
6487 from that they act the same way.
6489 The specification of commands can be provided in the filter arguments
6490 with the @var{commands} option, or in a file specified by the
6491 @var{filename} option.
6493 These filters accept the following options:
6496 Set the commands to be read and sent to the other filters.
6498 Set the filename of the commands to be read and sent to the other
6502 @subsection Commands syntax
6504 A commands description consists of a sequence of interval
6505 specifications, comprising a list of commands to be executed when a
6506 particular event related to that interval occurs. The occurring event
6507 is typically the current frame time entering or leaving a given time
6510 An interval is specified by the following syntax:
6512 @var{START}[-@var{END}] @var{COMMANDS};
6515 The time interval is specified by the @var{START} and @var{END} times.
6516 @var{END} is optional and defaults to the maximum time.
6518 The current frame time is considered within the specified interval if
6519 it is included in the interval [@var{START}, @var{END}), that is when
6520 the time is greater or equal to @var{START} and is lesser than
6523 @var{COMMANDS} consists of a sequence of one or more command
6524 specifications, separated by ",", relating to that interval. The
6525 syntax of a command specification is given by:
6527 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
6530 @var{FLAGS} is optional and specifies the type of events relating to
6531 the time interval which enable sending the specified command, and must
6532 be a non-null sequence of identifier flags separated by "+" or "|" and
6533 enclosed between "[" and "]".
6535 The following flags are recognized:
6538 The command is sent when the current frame timestamp enters the
6539 specified interval. In other words, the command is sent when the
6540 previous frame timestamp was not in the given interval, and the
6544 The command is sent when the current frame timestamp leaves the
6545 specified interval. In other words, the command is sent when the
6546 previous frame timestamp was in the given interval, and the
6550 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
6553 @var{TARGET} specifies the target of the command, usually the name of
6554 the filter class or a specific filter instance name.
6556 @var{COMMAND} specifies the name of the command for the target filter.
6558 @var{ARG} is optional and specifies the optional list of argument for
6559 the given @var{COMMAND}.
6561 Between one interval specification and another, whitespaces, or
6562 sequences of characters starting with @code{#} until the end of line,
6563 are ignored and can be used to annotate comments.
6565 A simplified BNF description of the commands specification syntax
6568 @var{COMMAND_FLAG} ::= "enter" | "leave"
6569 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
6570 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
6571 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
6572 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
6573 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
6576 @subsection Examples
6580 Specify audio tempo change at second 4:
6582 asendcmd=c='4.0 atempo tempo 1.5',atempo
6586 Specify a list of drawtext and hue commands in a file.
6588 # show text in the interval 5-10
6589 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
6590 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
6592 # desaturate the image in the interval 15-20
6593 15.0-20.0 [enter] hue reinit s=0,
6594 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
6595 [leave] hue reinit s=1,
6596 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
6598 # apply an exponential saturation fade-out effect, starting from time 25
6599 25 [enter] hue s=exp(t-25)
6602 A filtergraph allowing to read and process the above command list
6603 stored in a file @file{test.cmd}, can be specified with:
6605 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
6610 @section asetpts, setpts
6612 Change the PTS (presentation timestamp) of the input frames.
6614 @code{asetpts} works on audio frames, @code{setpts} on video frames.
6616 Accept in input an expression evaluated through the eval API, which
6617 can contain the following constants:
6621 frame rate, only defined for constant frame-rate video
6624 the presentation timestamp in input
6627 the count of the input frame, starting from 0.
6629 @item NB_CONSUMED_SAMPLES
6630 the number of consumed samples, not including the current frame (only
6634 the number of samples in the current frame (only audio)
6640 the PTS of the first frame
6643 the time in seconds of the first frame
6646 tell if the current frame is interlaced
6649 the time in seconds of the current frame
6655 original position in the file of the frame, or undefined if undefined
6656 for the current frame
6662 previous input time in seconds
6668 previous output time in seconds
6671 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
6675 wallclock (RTC) time at the start of the movie in microseconds
6678 @subsection Examples
6682 Start counting PTS from zero
6688 Apply fast motion effect:
6694 Apply slow motion effect:
6700 Set fixed rate of 25 frames per second:
6706 Set fixed rate 25 fps with some jitter:
6708 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6712 Apply an offset of 10 seconds to the input PTS:
6718 Generate timestamps from a "live source" and rebase onto the current timebase:
6720 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6726 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6727 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6728 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6729 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6731 The filter also has a video output (see the @var{video} option) with a real
6732 time graph to observe the loudness evolution. The graphic contains the logged
6733 message mentioned above, so it is not printed anymore when this option is set,
6734 unless the verbose logging is set. The main graphing area contains the
6735 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6736 the momentary loudness (400 milliseconds).
6738 More information about the Loudness Recommendation EBU R128 on
6739 @url{http://tech.ebu.ch/loudness}.
6741 The filter accepts the following named parameters:
6746 Activate the video output. The audio stream is passed unchanged whether this
6747 option is set or no. The video stream will be the first output stream if
6748 activated. Default is @code{0}.
6751 Set the video size. This option is for video only. Default and minimum
6752 resolution is @code{640x480}.
6755 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6756 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6757 other integer value between this range is allowed.
6760 Set metadata injection. If set to @code{1}, the audio input will be segmented
6761 into 100ms output frames, each of them containing various loudness information
6762 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
6764 Default is @code{0}.
6767 Force the frame logging level.
6769 Available values are:
6772 information logging level
6774 verbose logging level
6777 By default, the logging level is set to @var{info}. If the @option{video} or
6778 the @option{metadata} options are set, it switches to @var{verbose}.
6781 @subsection Examples
6785 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
6787 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6791 Run an analysis with @command{ffmpeg}:
6793 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6797 @section settb, asettb
6799 Set the timebase to use for the output frames timestamps.
6800 It is mainly useful for testing timebase configuration.
6802 This filter accepts a single option @option{tb}, which can be
6803 specified either by setting @option{tb}=@var{VALUE} or setting the
6806 The value for @option{tb} is an arithmetic expression representing a
6807 rational. The expression can contain the constants "AVTB" (the default
6808 timebase), "intb" (the input timebase) and "sr" (the sample rate,
6809 audio only). Default value is "intb".
6811 @subsection Examples
6815 Set the timebase to 1/25:
6821 Set the timebase to 1/10:
6827 Set the timebase to 1001/1000:
6833 Set the timebase to 2*intb:
6839 Set the default timebase value:
6847 Concatenate audio and video streams, joining them together one after the
6850 The filter works on segments of synchronized video and audio streams. All
6851 segments must have the same number of streams of each type, and that will
6852 also be the number of streams at output.
6854 The filter accepts the following named parameters:
6858 Set the number of segments. Default is 2.
6861 Set the number of output video streams, that is also the number of video
6862 streams in each segment. Default is 1.
6865 Set the number of output audio streams, that is also the number of video
6866 streams in each segment. Default is 0.
6869 Activate unsafe mode: do not fail if segments have a different format.
6873 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
6874 @var{a} audio outputs.
6876 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
6877 segment, in the same order as the outputs, then the inputs for the second
6880 Related streams do not always have exactly the same duration, for various
6881 reasons including codec frame size or sloppy authoring. For that reason,
6882 related synchronized streams (e.g. a video and its audio track) should be
6883 concatenated at once. The concat filter will use the duration of the longest
6884 stream in each segment (except the last one), and if necessary pad shorter
6885 audio streams with silence.
6887 For this filter to work correctly, all segments must start at timestamp 0.
6889 All corresponding streams must have the same parameters in all segments; the
6890 filtering system will automatically select a common pixel format for video
6891 streams, and a common sample format, sample rate and channel layout for
6892 audio streams, but other settings, such as resolution, must be converted
6893 explicitly by the user.
6895 Different frame rates are acceptable but will result in variable frame rate
6896 at output; be sure to configure the output file to handle it.
6898 @subsection Examples
6902 Concatenate an opening, an episode and an ending, all in bilingual version
6903 (video in stream 0, audio in streams 1 and 2):
6905 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
6906 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
6907 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
6908 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
6912 Concatenate two parts, handling audio and video separately, using the
6913 (a)movie sources, and adjusting the resolution:
6915 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
6916 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
6917 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
6919 Note that a desync will happen at the stitch if the audio and video streams
6920 do not have exactly the same duration in the first file.
6924 @section showspectrum
6926 Convert input audio to a video output, representing the audio frequency
6929 The filter accepts the following named parameters:
6932 Specify the video size for the output. Default value is @code{640x512}.
6935 Specify if the spectrum should slide along the window. Default value is
6939 Specify display mode.
6941 It accepts the following values:
6944 all channels are displayed in the same row
6946 all channels are displayed in separate rows
6949 Default value is @samp{combined}.
6952 Specify display color mode.
6954 It accepts the following values:
6957 each channel is displayed in a separate color
6959 each channel is is displayed using the same color scheme
6962 Default value is @samp{channel}.
6965 Specify scale used for calculating intensity color values.
6967 It accepts the following values:
6972 square root, default
6979 Default value is @samp{sqrt}.
6982 Set saturation modifier for displayed colors. Negative values provide
6983 alternative color scheme. @code{0} is no saturation at all.
6984 Saturation must be in [-10.0, 10.0] range.
6985 Default value is @code{1}.
6988 The usage is very similar to the showwaves filter; see the examples in that
6991 @subsection Examples
6995 Large window with logarithmic color scaling:
6997 showspectrum=s=1280x480:scale=log
7001 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
7003 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
7004 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
7010 Convert input audio to a video output, representing the samples waves.
7012 The filter accepts the following named parameters:
7017 Available values are:
7020 Draw a point for each sample.
7023 Draw a vertical line for each sample.
7026 Default value is @code{point}.
7029 Set the number of samples which are printed on the same column. A
7030 larger value will decrease the frame rate. Must be a positive
7031 integer. This option can be set only if the value for @var{rate}
7032 is not explicitly specified.
7035 Set the (approximate) output frame rate. This is done by setting the
7036 option @var{n}. Default value is "25".
7039 Specify the video size for the output. Default value is "600x240".
7042 @subsection Examples
7046 Output the input file audio and the corresponding video representation
7049 amovie=a.mp3,asplit[out0],showwaves[out1]
7053 Create a synthetic signal and show it with showwaves, forcing a
7054 frame rate of 30 frames per second:
7056 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
7060 @c man end MULTIMEDIA FILTERS
7062 @chapter Multimedia Sources
7063 @c man begin MULTIMEDIA SOURCES
7065 Below is a description of the currently available multimedia sources.
7069 This is the same as @ref{movie} source, except it selects an audio
7075 Read audio and/or video stream(s) from a movie container.
7077 It accepts the syntax: @var{movie_name}[:@var{options}] where
7078 @var{movie_name} is the name of the resource to read (not necessarily
7079 a file but also a device or a stream accessed through some protocol),
7080 and @var{options} is an optional sequence of @var{key}=@var{value}
7081 pairs, separated by ":".
7083 The description of the accepted options follows.
7087 @item format_name, f
7088 Specifies the format assumed for the movie to read, and can be either
7089 the name of a container or an input device. If not specified the
7090 format is guessed from @var{movie_name} or by probing.
7092 @item seek_point, sp
7093 Specifies the seek point in seconds, the frames will be output
7094 starting from this seek point, the parameter is evaluated with
7095 @code{av_strtod} so the numerical value may be suffixed by an IS
7096 postfix. Default value is "0".
7099 Specifies the streams to read. Several streams can be specified,
7100 separated by "+". The source will then have as many outputs, in the
7101 same order. The syntax is explained in the ``Stream specifiers''
7102 section in the ffmpeg manual. Two special names, "dv" and "da" specify
7103 respectively the default (best suited) video and audio stream. Default
7104 is "dv", or "da" if the filter is called as "amovie".
7106 @item stream_index, si
7107 Specifies the index of the video stream to read. If the value is -1,
7108 the best suited video stream will be automatically selected. Default
7109 value is "-1". Deprecated. If the filter is called "amovie", it will select
7110 audio instead of video.
7113 Specifies how many times to read the stream in sequence.
7114 If the value is less than 1, the stream will be read again and again.
7115 Default value is "1".
7117 Note that when the movie is looped the source timestamps are not
7118 changed, so it will generate non monotonically increasing timestamps.
7121 This filter allows to overlay a second video on top of main input of
7122 a filtergraph as shown in this graph:
7124 input -----------> deltapts0 --> overlay --> output
7127 movie --> scale--> deltapts1 -------+
7130 @subsection Examples
7134 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
7135 on top of the input labelled as "in":
7137 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
7138 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
7142 Read from a video4linux2 device, and overlay it on top of the input
7145 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
7146 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
7150 Read the first video stream and the audio stream with id 0x81 from
7151 dvd.vob; the video is connected to the pad named "video" and the audio is
7152 connected to the pad named "audio":
7154 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
7158 @c man end MULTIMEDIA SOURCES