1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 In libavfilter, a filter can have multiple inputs and multiple
8 To illustrate the sorts of things that are possible, we consider the
12 input --> split ---------------------> overlay --> output
15 +-----> crop --> vflip -------+
18 This filtergraph splits the input stream in two streams, sends one
19 stream through the crop filter and the vflip filter before merging it
20 back with the other stream by overlaying it on top. You can use the
21 following command to achieve this:
24 ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT
27 The result will be that in output the top half of the video is mirrored
30 Filters in the same linear chain are separated by commas, and distinct
31 linear chains of filters are separated by semicolons. In our example,
32 @var{crop,vflip} are in one linear chain, @var{split} and
33 @var{overlay} are separately in another. The points where the linear
34 chains join are labelled by names enclosed in square brackets. In the
35 example, the split filter generates two outputs that are associated to
36 the labels @var{[main]} and @var{[tmp]}.
38 The stream sent to the second output of @var{split}, labelled as
39 @var{[tmp]}, is processed through the @var{crop} filter, which crops
40 away the lower half part of the video, and then vertically flipped. The
41 @var{overlay} filter takes in input the first unchanged output of the
42 split filter (which was labelled as @var{[main]}), and overlay on its
43 lower half the output generated by the @var{crop,vflip} filterchain.
45 Some filters take in input a list of parameters: they are specified
46 after the filter name and an equal sign, and are separated from each other
49 There exist so-called @var{source filters} that do not have an
50 audio/video input, and @var{sink filters} that will not have audio/video
53 @c man end FILTERING INTRODUCTION
56 @c man begin GRAPH2DOT
58 The @file{graph2dot} program included in the FFmpeg @file{tools}
59 directory can be used to parse a filtergraph description and issue a
60 corresponding textual representation in the dot language.
67 to see how to use @file{graph2dot}.
69 You can then pass the dot description to the @file{dot} program (from
70 the graphviz suite of programs) and obtain a graphical representation
73 For example the sequence of commands:
75 echo @var{GRAPH_DESCRIPTION} | \
76 tools/graph2dot -o graph.tmp && \
77 dot -Tpng graph.tmp -o graph.png && \
81 can be used to create and display an image representing the graph
82 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
83 a complete self-contained graph, with its inputs and outputs explicitly defined.
84 For example if your command line is of the form:
86 ffmpeg -i infile -vf scale=640:360 outfile
88 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
90 nullsrc,scale=640:360,nullsink
92 you may also need to set the @var{nullsrc} parameters and add a @var{format}
93 filter in order to simulate a specific input file.
97 @chapter Filtergraph description
98 @c man begin FILTERGRAPH DESCRIPTION
100 A filtergraph is a directed graph of connected filters. It can contain
101 cycles, and there can be multiple links between a pair of
102 filters. Each link has one input pad on one side connecting it to one
103 filter from which it takes its input, and one output pad on the other
104 side connecting it to the one filter accepting its output.
106 Each filter in a filtergraph is an instance of a filter class
107 registered in the application, which defines the features and the
108 number of input and output pads of the filter.
110 A filter with no input pads is called a "source", a filter with no
111 output pads is called a "sink".
113 @anchor{Filtergraph syntax}
114 @section Filtergraph syntax
116 A filtergraph can be represented using a textual representation, which is
117 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
118 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
119 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
120 @file{libavfilter/avfiltergraph.h}.
122 A filterchain consists of a sequence of connected filters, each one
123 connected to the previous one in the sequence. A filterchain is
124 represented by a list of ","-separated filter descriptions.
126 A filtergraph consists of a sequence of filterchains. A sequence of
127 filterchains is represented by a list of ";"-separated filterchain
130 A filter is represented by a string of the form:
131 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
133 @var{filter_name} is the name of the filter class of which the
134 described filter is an instance of, and has to be the name of one of
135 the filter classes registered in the program.
136 The name of the filter class is optionally followed by a string
139 @var{arguments} is a string which contains the parameters used to
140 initialize the filter instance. It may have one of the two allowed forms:
144 A ':'-separated list of @var{key=value} pairs.
147 A ':'-separated list of @var{value}. In this case, the keys are assumed to be
148 the option names in the order they are declared. E.g. the @code{fade} filter
149 declares three options in this order -- @option{type}, @option{start_frame} and
150 @option{nb_frames}. Then the parameter list @var{in:0:30} means that the value
151 @var{in} is assigned to the option @option{type}, @var{0} to
152 @option{start_frame} and @var{30} to @option{nb_frames}.
156 If the option value itself is a list of items (e.g. the @code{format} filter
157 takes a list of pixel formats), the items in the list are usually separated by
160 The list of arguments can be quoted using the character "'" as initial
161 and ending mark, and the character '\' for escaping the characters
162 within the quoted text; otherwise the argument string is considered
163 terminated when the next special character (belonging to the set
164 "[]=;,") is encountered.
166 The name and arguments of the filter are optionally preceded and
167 followed by a list of link labels.
168 A link label allows to name a link and associate it to a filter output
169 or input pad. The preceding labels @var{in_link_1}
170 ... @var{in_link_N}, are associated to the filter input pads,
171 the following labels @var{out_link_1} ... @var{out_link_M}, are
172 associated to the output pads.
174 When two link labels with the same name are found in the
175 filtergraph, a link between the corresponding input and output pad is
178 If an output pad is not labelled, it is linked by default to the first
179 unlabelled input pad of the next filter in the filterchain.
180 For example in the filterchain:
182 nullsrc, split[L1], [L2]overlay, nullsink
184 the split filter instance has two output pads, and the overlay filter
185 instance two input pads. The first output pad of split is labelled
186 "L1", the first input pad of overlay is labelled "L2", and the second
187 output pad of split is linked to the second input pad of overlay,
188 which are both unlabelled.
190 In a complete filterchain all the unlabelled filter input and output
191 pads must be connected. A filtergraph is considered valid if all the
192 filter input and output pads of all the filterchains are connected.
194 Libavfilter will automatically insert scale filters where format
195 conversion is required. It is possible to specify swscale flags
196 for those automatically inserted scalers by prepending
197 @code{sws_flags=@var{flags};}
198 to the filtergraph description.
200 Follows a BNF description for the filtergraph syntax:
202 @var{NAME} ::= sequence of alphanumeric characters and '_'
203 @var{LINKLABEL} ::= "[" @var{NAME} "]"
204 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
205 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
206 @var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
207 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
208 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
211 @section Notes on filtergraph escaping
213 Some filter arguments require the use of special characters, typically
214 @code{:} to separate key=value pairs in a named options list. In this
215 case the user should perform a first level escaping when specifying
216 the filter arguments. For example, consider the following literal
217 string to be embedded in the @ref{drawtext} filter arguments:
219 this is a 'string': may contain one, or more, special characters
222 Since @code{:} is special for the filter arguments syntax, it needs to
223 be escaped, so you get:
225 text=this is a \'string\'\: may contain one, or more, special characters
228 A second level of escaping is required when embedding the filter
229 arguments in a filtergraph description, in order to escape all the
230 filtergraph special characters. Thus the example above becomes:
232 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
235 Finally an additional level of escaping may be needed when writing the
236 filtergraph description in a shell command, which depends on the
237 escaping rules of the adopted shell. For example, assuming that
238 @code{\} is special and needs to be escaped with another @code{\}, the
239 previous string will finally result in:
241 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
244 Sometimes, it might be more convenient to employ quoting in place of
245 escaping. For example the string:
247 Caesar: tu quoque, Brute, fili mi
250 Can be quoted in the filter arguments as:
252 text='Caesar: tu quoque, Brute, fili mi'
255 And finally inserted in a filtergraph like:
257 drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
260 See the ``Quoting and escaping'' section in the ffmpeg-utils manual
261 for more information about the escaping and quoting rules adopted by
264 @c man end FILTERGRAPH DESCRIPTION
266 @chapter Audio Filters
267 @c man begin AUDIO FILTERS
269 When you configure your FFmpeg build, you can disable any of the
270 existing filters using @code{--disable-filters}.
271 The configure output will show the audio filters included in your
274 Below is a description of the currently available audio filters.
278 Convert the input audio format to the specified formats.
280 The filter accepts a string of the form:
281 "@var{sample_format}:@var{channel_layout}".
283 @var{sample_format} specifies the sample format, and can be a string or the
284 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
285 suffix for a planar sample format.
287 @var{channel_layout} specifies the channel layout, and can be a string
288 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
290 The special parameter "auto", signifies that the filter will
291 automatically select the output format depending on the output filter.
297 Convert input to float, planar, stereo:
303 Convert input to unsigned 8-bit, automatically select out channel layout:
311 Apply a two-pole all-pass filter with central frequency (in Hz)
312 @var{frequency}, and filter-width @var{width}.
313 An all-pass filter changes the audio's frequency to phase relationship
314 without changing its frequency to amplitude relationship.
316 The filter accepts parameters as a list of @var{key}=@var{value}
317 pairs, separated by ":".
319 A description of the accepted parameters follows.
326 Set method to specify band-width of filter.
339 Specify the band-width of a filter in width_type units.
344 Apply a high-pass filter with 3dB point frequency.
345 The filter can be either single-pole, or double-pole (the default).
346 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
348 The filter accepts parameters as a list of @var{key}=@var{value}
349 pairs, separated by ":".
351 A description of the accepted parameters follows.
355 Set frequency in Hz. Default is 3000.
358 Set number of poles. Default is 2.
361 Set method to specify band-width of filter.
374 Specify the band-width of a filter in width_type units.
375 Applies only to double-pole filter.
376 The default is 0.707q and gives a Butterworth response.
381 Apply a low-pass filter with 3dB point frequency.
382 The filter can be either single-pole or double-pole (the default).
383 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
385 The filter accepts parameters as a list of @var{key}=@var{value}
386 pairs, separated by ":".
388 A description of the accepted parameters follows.
392 Set frequency in Hz. Default is 500.
395 Set number of poles. Default is 2.
398 Set method to specify band-width of filter.
411 Specify the band-width of a filter in width_type units.
412 Applies only to double-pole filter.
413 The default is 0.707q and gives a Butterworth response.
418 Boost or cut the bass (lower) frequencies of the audio using a two-pole
419 shelving filter with a response similar to that of a standard
420 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
422 The filter accepts parameters as a list of @var{key}=@var{value}
423 pairs, separated by ":".
425 A description of the accepted parameters follows.
429 Give the gain at 0 Hz. Its useful range is about -20
430 (for a large cut) to +20 (for a large boost).
431 Beware of clipping when using a positive gain.
434 Set the filter's central frequency and so can be used
435 to extend or reduce the frequency range to be boosted or cut.
436 The default value is @code{100} Hz.
439 Set method to specify band-width of filter.
452 Determine how steep is the filter's shelf transition.
457 Boost or cut treble (upper) frequencies of the audio using a two-pole
458 shelving filter with a response similar to that of a standard
459 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
461 The filter accepts parameters as a list of @var{key}=@var{value}
462 pairs, separated by ":".
464 A description of the accepted parameters follows.
468 Give the gain at whichever is the lower of ~22 kHz and the
469 Nyquist frequency. Its useful range is about -20 (for a large cut)
470 to +20 (for a large boost). Beware of clipping when using a positive gain.
473 Set the filter's central frequency and so can be used
474 to extend or reduce the frequency range to be boosted or cut.
475 The default value is @code{3000} Hz.
478 Set method to specify band-width of filter.
491 Determine how steep is the filter's shelf transition.
496 Apply a two-pole Butterworth band-pass filter with central
497 frequency @var{frequency}, and (3dB-point) band-width width.
498 The @var{csg} option selects a constant skirt gain (peak gain = Q)
499 instead of the default: constant 0dB peak gain.
500 The filter roll off at 6dB per octave (20dB per decade).
502 The filter accepts parameters as a list of @var{key}=@var{value}
503 pairs, separated by ":".
505 A description of the accepted parameters follows.
509 Set the filter's central frequency. Default is @code{3000}.
512 Constant skirt gain if set to 1. Defaults to 0.
515 Set method to specify band-width of filter.
528 Specify the band-width of a filter in width_type units.
533 Apply a two-pole Butterworth band-reject filter with central
534 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
535 The filter roll off at 6dB per octave (20dB per decade).
537 The filter accepts parameters as a list of @var{key}=@var{value}
538 pairs, separated by ":".
540 A description of the accepted parameters follows.
544 Set the filter's central frequency. Default is @code{3000}.
547 Set method to specify band-width of filter.
560 Specify the band-width of a filter in width_type units.
565 Apply a biquad IIR filter with the given coefficients.
566 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
567 are the numerator and denominator coefficients respectively.
571 Apply a two-pole peaking equalisation (EQ) filter. With this
572 filter, the signal-level at and around a selected frequency can
573 be increased or decreased, whilst (unlike bandpass and bandreject
574 filters) that at all other frequencies is unchanged.
576 In order to produce complex equalisation curves, this filter can
577 be given several times, each with a different central frequency.
579 The filter accepts parameters as a list of @var{key}=@var{value}
580 pairs, separated by ":".
582 A description of the accepted parameters follows.
586 Set the filter's central frequency in Hz.
589 Set method to specify band-width of filter.
602 Specify the band-width of a filter in width_type units.
605 Set the required gain or attenuation in dB.
606 Beware of clipping when using a positive gain.
611 Apply fade-in/out effect to input audio.
613 The filter accepts parameters as a list of @var{key}=@var{value}
614 pairs, separated by ":".
616 A description of the accepted parameters follows.
620 Specify the effect type, can be either @code{in} for fade-in, or
621 @code{out} for a fade-out effect. Default is @code{in}.
623 @item start_sample, ss
624 Specify the number of the start sample for starting to apply the fade
625 effect. Default is 0.
628 Specify the number of samples for which the fade effect has to last. At
629 the end of the fade-in effect the output audio will have the same
630 volume as the input audio, at the end of the fade-out transition
631 the output audio will be silence. Default is 44100.
634 Specify time in seconds for starting to apply the fade
635 effect. Default is 0.
636 If set this option is used instead of @var{start_sample} one.
639 Specify the number of seconds for which the fade effect has to last. At
640 the end of the fade-in effect the output audio will have the same
641 volume as the input audio, at the end of the fade-out transition
642 the output audio will be silence. Default is 0.
643 If set this option is used instead of @var{nb_samples} one.
646 Set curve for fade transition.
648 It accepts the following values:
651 select triangular, linear slope (default)
653 select quarter of sine wave
655 select half of sine wave
657 select exponential sine wave
661 select inverted parabola
677 Fade in first 15 seconds of audio:
683 Fade out last 25 seconds of a 900 seconds audio:
685 afade=t=out:ss=875:d=25
692 Set output format constraints for the input audio. The framework will
693 negotiate the most appropriate format to minimize conversions.
695 The filter accepts the following named parameters:
699 A '|'-separated list of requested sample formats.
702 A '|'-separated list of requested sample rates.
704 @item channel_layouts
705 A '|'-separated list of requested channel layouts.
709 If a parameter is omitted, all values are allowed.
711 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
713 aformat=sample_fmts=u8|s16:channel_layouts=stereo
718 Merge two or more audio streams into a single multi-channel stream.
720 The filter accepts the following named options:
725 Set the number of inputs. Default is 2.
729 If the channel layouts of the inputs are disjoint, and therefore compatible,
730 the channel layout of the output will be set accordingly and the channels
731 will be reordered as necessary. If the channel layouts of the inputs are not
732 disjoint, the output will have all the channels of the first input then all
733 the channels of the second input, in that order, and the channel layout of
734 the output will be the default value corresponding to the total number of
737 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
738 is FC+BL+BR, then the output will be in 5.1, with the channels in the
739 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
740 first input, b1 is the first channel of the second input).
742 On the other hand, if both input are in stereo, the output channels will be
743 in the default order: a1, a2, b1, b2, and the channel layout will be
744 arbitrarily set to 4.0, which may or may not be the expected value.
746 All inputs must have the same sample rate, and format.
748 If inputs do not have the same duration, the output will stop with the
755 Merge two mono files into a stereo stream:
757 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
764 amovie=input.mkv:si=0 [a0];
765 amovie=input.mkv:si=1 [a1];
766 amovie=input.mkv:si=2 [a2];
767 amovie=input.mkv:si=3 [a3];
768 amovie=input.mkv:si=4 [a4];
769 amovie=input.mkv:si=5 [a5];
770 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
776 Mixes multiple audio inputs into a single output.
780 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
782 will mix 3 input audio streams to a single output with the same duration as the
783 first input and a dropout transition time of 3 seconds.
785 The filter accepts the following named parameters:
789 Number of inputs. If unspecified, it defaults to 2.
792 How to determine the end-of-stream.
796 Duration of longest input. (default)
799 Duration of shortest input.
802 Duration of first input.
806 @item dropout_transition
807 Transition time, in seconds, for volume renormalization when an input
808 stream ends. The default value is 2 seconds.
814 Pass the audio source unchanged to the output.
818 Pad the end of a audio stream with silence, this can be used together with
819 -shortest to extend audio streams to the same length as the video stream.
824 Resample the input audio to the specified parameters, using the
825 libswresample library. If none are specified then the filter will
826 automatically convert between its input and output.
828 This filter is also able to stretch/squeeze the audio data to make it match
829 the timestamps or to inject silence / cut out audio to make it match the
830 timestamps, do a combination of both or do neither.
832 The filter accepts the syntax
833 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
834 expresses a sample rate and @var{resampler_options} is a list of
835 @var{key}=@var{value} pairs, separated by ":". See the
836 ffmpeg-resampler manual for the complete list of supported options.
842 Resample the input audio to 44100Hz:
848 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
849 samples per second compensation:
855 @section asetnsamples
857 Set the number of samples per each output audio frame.
859 The last output packet may contain a different number of samples, as
860 the filter will flush all the remaining samples when the input audio
863 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
868 @item nb_out_samples, n
869 Set the number of frames per each output audio frame. The number is
870 intended as the number of samples @emph{per each channel}.
871 Default value is 1024.
874 If set to 1, the filter will pad the last audio frame with zeroes, so
875 that the last frame will contain the same number of samples as the
876 previous ones. Default value is 1.
879 For example, to set the number of per-frame samples to 1234 and
880 disable padding for the last frame, use:
882 asetnsamples=n=1234:p=0
887 Show a line containing various information for each input audio frame.
888 The input audio is not modified.
890 The shown line contains a sequence of key/value pairs of the form
891 @var{key}:@var{value}.
893 A description of each shown parameter follows:
897 sequential number of the input frame, starting from 0
900 Presentation timestamp of the input frame, in time base units; the time base
901 depends on the filter input pad, and is usually 1/@var{sample_rate}.
904 presentation timestamp of the input frame in seconds
907 position of the frame in the input stream, -1 if this information in
908 unavailable and/or meaningless (for example in case of synthetic audio)
917 sample rate for the audio frame
920 number of samples (per channel) in the frame
923 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
924 the data is treated as if all the planes were concatenated.
926 @item plane_checksums
927 A list of Adler-32 checksums for each data plane.
932 Split input audio into several identical outputs.
934 The filter accepts a single parameter which specifies the number of outputs. If
935 unspecified, it defaults to 2.
939 [in] asplit [out0][out1]
942 will create two separate outputs from the same input.
944 To create 3 or more outputs, you need to specify the number of
947 [in] asplit=3 [out0][out1][out2]
951 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
953 will create 5 copies of the input audio.
958 Forward two audio streams and control the order the buffers are forwarded.
960 The argument to the filter is an expression deciding which stream should be
961 forwarded next: if the result is negative, the first stream is forwarded; if
962 the result is positive or zero, the second stream is forwarded. It can use
963 the following variables:
967 number of buffers forwarded so far on each stream
969 number of samples forwarded so far on each stream
971 current timestamp of each stream
974 The default value is @code{t1-t2}, which means to always forward the stream
975 that has a smaller timestamp.
977 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
978 input, while avoiding too much of a desynchronization:
980 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
981 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
989 The filter accepts exactly one parameter, the audio tempo. If not
990 specified then the filter will assume nominal 1.0 tempo. Tempo must
991 be in the [0.5, 2.0] range.
997 Slow down audio to 80% tempo:
1003 To speed up audio to 125% tempo:
1011 Make audio easier to listen to on headphones.
1013 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1014 so that when listened to on headphones the stereo image is moved from
1015 inside your head (standard for headphones) to outside and in front of
1016 the listener (standard for speakers).
1022 Mix channels with specific gain levels. The filter accepts the output
1023 channel layout followed by a set of channels definitions.
1025 This filter is also designed to remap efficiently the channels of an audio
1028 The filter accepts parameters of the form:
1029 "@var{l}:@var{outdef}:@var{outdef}:..."
1033 output channel layout or number of channels
1036 output channel specification, of the form:
1037 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1040 output channel to define, either a channel name (FL, FR, etc.) or a channel
1041 number (c0, c1, etc.)
1044 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1047 input channel to use, see out_name for details; it is not possible to mix
1048 named and numbered input channels
1051 If the `=' in a channel specification is replaced by `<', then the gains for
1052 that specification will be renormalized so that the total is 1, thus
1053 avoiding clipping noise.
1055 @subsection Mixing examples
1057 For example, if you want to down-mix from stereo to mono, but with a bigger
1058 factor for the left channel:
1060 pan=1:c0=0.9*c0+0.1*c1
1063 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1064 7-channels surround:
1066 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1069 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1070 that should be preferred (see "-ac" option) unless you have very specific
1073 @subsection Remapping examples
1075 The channel remapping will be effective if, and only if:
1078 @item gain coefficients are zeroes or ones,
1079 @item only one input per channel output,
1082 If all these conditions are satisfied, the filter will notify the user ("Pure
1083 channel mapping detected"), and use an optimized and lossless method to do the
1086 For example, if you have a 5.1 source and want a stereo audio stream by
1087 dropping the extra channels:
1089 pan="stereo: c0=FL : c1=FR"
1092 Given the same source, you can also switch front left and front right channels
1093 and keep the input channel layout:
1095 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1098 If the input is a stereo audio stream, you can mute the front left channel (and
1099 still keep the stereo channel layout) with:
1104 Still with a stereo audio stream input, you can copy the right channel in both
1105 front left and right:
1107 pan="stereo: c0=FR : c1=FR"
1110 @section silencedetect
1112 Detect silence in an audio stream.
1114 This filter logs a message when it detects that the input audio volume is less
1115 or equal to a noise tolerance value for a duration greater or equal to the
1116 minimum detected noise duration.
1118 The printed times and duration are expressed in seconds.
1120 The filter accepts the following options:
1124 Set silence duration until notification (default is 2 seconds).
1127 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1128 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1131 @subsection Examples
1135 Detect 5 seconds of silence with -50dB noise tolerance:
1137 silencedetect=n=-50dB:d=5
1141 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1142 tolerance in @file{silence.mp3}:
1144 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
1149 Synchronize audio data with timestamps by squeezing/stretching it and/or
1150 dropping samples/adding silence when needed.
1152 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1154 The filter accepts the following named parameters:
1158 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1159 by default. When disabled, time gaps are covered with silence.
1162 Minimum difference between timestamps and audio data (in seconds) to trigger
1163 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1164 this filter, try setting this parameter to 0.
1167 Maximum compensation in samples per second. Relevant only with compensate=1.
1171 Assume the first pts should be this value. The time base is 1 / sample rate.
1172 This allows for padding/trimming at the start of stream. By default, no
1173 assumption is made about the first frame's expected pts, so no padding or
1174 trimming is done. For example, this could be set to 0 to pad the beginning with
1175 silence if an audio stream starts after the video stream or to trim any samples
1176 with a negative pts due to encoder delay.
1180 @section channelsplit
1181 Split each channel in input audio stream into a separate output stream.
1183 This filter accepts the following named parameters:
1185 @item channel_layout
1186 Channel layout of the input stream. Default is "stereo".
1189 For example, assuming a stereo input MP3 file
1191 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1193 will create an output Matroska file with two audio streams, one containing only
1194 the left channel and the other the right channel.
1196 To split a 5.1 WAV file into per-channel files
1198 ffmpeg -i in.wav -filter_complex
1199 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1200 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1201 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1206 Remap input channels to new locations.
1208 This filter accepts the following named parameters:
1210 @item channel_layout
1211 Channel layout of the output stream.
1214 Map channels from input to output. The argument is a comma-separated list of
1215 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1216 @var{in_channel} form. @var{in_channel} can be either the name of the input
1217 channel (e.g. FL for front left) or its index in the input channel layout.
1218 @var{out_channel} is the name of the output channel or its index in the output
1219 channel layout. If @var{out_channel} is not given then it is implicitly an
1220 index, starting with zero and increasing by one for each mapping.
1223 If no mapping is present, the filter will implicitly map input channels to
1224 output channels preserving index.
1226 For example, assuming a 5.1+downmix input MOV file
1228 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
1230 will create an output WAV file tagged as stereo from the downmix channels of
1233 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1235 ffmpeg -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
1239 Join multiple input streams into one multi-channel stream.
1241 The filter accepts the following named parameters:
1245 Number of input streams. Defaults to 2.
1247 @item channel_layout
1248 Desired output channel layout. Defaults to stereo.
1251 Map channels from inputs to output. The argument is a comma-separated list of
1252 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1253 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1254 can be either the name of the input channel (e.g. FL for front left) or its
1255 index in the specified input stream. @var{out_channel} is the name of the output
1259 The filter will attempt to guess the mappings when those are not specified
1260 explicitly. It does so by first trying to find an unused matching input channel
1261 and if that fails it picks the first unused input channel.
1263 E.g. to join 3 inputs (with properly set channel layouts)
1265 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1268 To build a 5.1 output from 6 single-channel streams:
1270 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1271 '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'
1276 Convert the audio sample format, sample rate and channel layout. This filter is
1277 not meant to be used directly.
1281 Adjust the input audio volume.
1283 The filter accepts the following named parameters. If the key of the
1284 first options is omitted, the arguments are interpreted according to
1285 the following syntax:
1287 volume=@var{volume}:@var{precision}
1293 Expresses how the audio volume will be increased or decreased.
1295 Output values are clipped to the maximum value.
1297 The output audio volume is given by the relation:
1299 @var{output_volume} = @var{volume} * @var{input_volume}
1302 Default value for @var{volume} is 1.0.
1305 Set the mathematical precision.
1307 This determines which input sample formats will be allowed, which affects the
1308 precision of the volume scaling.
1312 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1314 32-bit floating-point; limits input sample format to FLT. (default)
1316 64-bit floating-point; limits input sample format to DBL.
1320 @subsection Examples
1324 Halve the input audio volume:
1328 volume=volume=-6.0206dB
1331 In all the above example the named key for @option{volume} can be
1332 omitted, for example like in:
1338 Increase input audio power by 6 decibels using fixed-point precision:
1340 volume=volume=6dB:precision=fixed
1344 @section volumedetect
1346 Detect the volume of the input video.
1348 The filter has no parameters. The input is not modified. Statistics about
1349 the volume will be printed in the log when the input stream end is reached.
1351 In particular it will show the mean volume (root mean square), maximum
1352 volume (on a per-sample basis), and the beginning of an histogram of the
1353 registered volume values (from the maximum value to a cumulated 1/1000 of
1356 All volumes are in decibels relative to the maximum PCM value.
1358 @subsection Examples
1360 Here is an excerpt of the output:
1362 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1363 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1364 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1365 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1366 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1367 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1368 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1369 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1370 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1376 The mean square energy is approximately -27 dB, or 10^-2.7.
1378 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1380 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1383 In other words, raising the volume by +4 dB does not cause any clipping,
1384 raising it by +5 dB causes clipping for 6 samples, etc.
1386 @c man end AUDIO FILTERS
1388 @chapter Audio Sources
1389 @c man begin AUDIO SOURCES
1391 Below is a description of the currently available audio sources.
1395 Buffer audio frames, and make them available to the filter chain.
1397 This source is mainly intended for a programmatic use, in particular
1398 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1400 It accepts the following mandatory parameters:
1401 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
1406 The sample rate of the incoming audio buffers.
1409 The sample format of the incoming audio buffers.
1410 Either a sample format name or its corresponging integer representation from
1411 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1413 @item channel_layout
1414 The channel layout of the incoming audio buffers.
1415 Either a channel layout name from channel_layout_map in
1416 @file{libavutil/channel_layout.c} or its corresponding integer representation
1417 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1420 The number of channels of the incoming audio buffers.
1421 If both @var{channels} and @var{channel_layout} are specified, then they
1426 @subsection Examples
1429 abuffer=44100:s16p:stereo
1432 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1433 Since the sample format with name "s16p" corresponds to the number
1434 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1442 Generate an audio signal specified by an expression.
1444 This source accepts in input one or more expressions (one for each
1445 channel), which are evaluated and used to generate a corresponding
1448 It accepts the syntax: @var{exprs}[::@var{options}].
1449 @var{exprs} is a list of expressions separated by ":", one for each
1450 separate channel. In case the @var{channel_layout} is not
1451 specified, the selected channel layout depends on the number of
1452 provided expressions.
1454 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1457 The description of the accepted options follows.
1461 @item channel_layout, c
1462 Set the channel layout. The number of channels in the specified layout
1463 must be equal to the number of specified expressions.
1466 Set the minimum duration of the sourced audio. See the function
1467 @code{av_parse_time()} for the accepted format.
1468 Note that the resulting duration may be greater than the specified
1469 duration, as the generated audio is always cut at the end of a
1472 If not specified, or the expressed duration is negative, the audio is
1473 supposed to be generated forever.
1476 Set the number of samples per channel per each output frame,
1479 @item sample_rate, s
1480 Specify the sample rate, default to 44100.
1483 Each expression in @var{exprs} can contain the following constants:
1487 number of the evaluated sample, starting from 0
1490 time of the evaluated sample expressed in seconds, starting from 0
1497 @subsection Examples
1507 Generate a sin signal with frequency of 440 Hz, set sample rate to
1510 aevalsrc="sin(440*2*PI*t)::s=8000"
1514 Generate a two channels signal, specify the channel layout (Front
1515 Center + Back Center) explicitly:
1517 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1521 Generate white noise:
1523 aevalsrc="-2+random(0)"
1527 Generate an amplitude modulated signal:
1529 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1533 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1535 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1542 Null audio source, return unprocessed audio frames. It is mainly useful
1543 as a template and to be employed in analysis / debugging tools, or as
1544 the source for filters which ignore the input data (for example the sox
1547 It accepts an optional sequence of @var{key}=@var{value} pairs,
1550 The description of the accepted options follows.
1554 @item sample_rate, s
1555 Specify the sample rate, and defaults to 44100.
1557 @item channel_layout, cl
1559 Specify the channel layout, and can be either an integer or a string
1560 representing a channel layout. The default value of @var{channel_layout}
1563 Check the channel_layout_map definition in
1564 @file{libavutil/channel_layout.c} for the mapping between strings and
1565 channel layout values.
1568 Set the number of samples per requested frames.
1572 @subsection Examples
1576 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1578 anullsrc=r=48000:cl=4
1582 Do the same operation with a more obvious syntax:
1584 anullsrc=r=48000:cl=mono
1589 Buffer audio frames, and make them available to the filter chain.
1591 This source is not intended to be part of user-supplied graph descriptions but
1592 for insertion by calling programs through the interface defined in
1593 @file{libavfilter/buffersrc.h}.
1595 It accepts the following named parameters:
1599 Timebase which will be used for timestamps of submitted frames. It must be
1600 either a floating-point number or in @var{numerator}/@var{denominator} form.
1606 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1608 @item channel_layout
1609 Channel layout of the audio data, in the form that can be accepted by
1610 @code{av_get_channel_layout()}.
1613 All the parameters need to be explicitly defined.
1617 Synthesize a voice utterance using the libflite library.
1619 To enable compilation of this filter you need to configure FFmpeg with
1620 @code{--enable-libflite}.
1622 Note that the flite library is not thread-safe.
1624 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1627 The description of the accepted parameters follows.
1632 If set to 1, list the names of the available voices and exit
1633 immediately. Default value is 0.
1636 Set the maximum number of samples per frame. Default value is 512.
1639 Set the filename containing the text to speak.
1642 Set the text to speak.
1645 Set the voice to use for the speech synthesis. Default value is
1646 @code{kal}. See also the @var{list_voices} option.
1649 @subsection Examples
1653 Read from file @file{speech.txt}, and synthetize the text using the
1654 standard flite voice:
1656 flite=textfile=speech.txt
1660 Read the specified text selecting the @code{slt} voice:
1662 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1666 Input text to ffmpeg:
1668 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1672 Make @file{ffplay} speak the specified text, using @code{flite} and
1673 the @code{lavfi} device:
1675 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1679 For more information about libflite, check:
1680 @url{http://www.speech.cs.cmu.edu/flite/}
1684 Generate an audio signal made of a sine wave with amplitude 1/8.
1686 The audio signal is bit-exact.
1688 It accepts a list of options in the form of @var{key}=@var{value} pairs
1689 separated by ":". If the option name is omitted, the first option is the
1690 frequency and the second option is the beep factor.
1692 The supported options are:
1697 Set the carrier frequency. Default is 440 Hz.
1699 @item beep_factor, b
1700 Enable a periodic beep every second with frequency @var{beep_factor} times
1701 the carrier frequency. Default is 0, meaning the beep is disabled.
1703 @item sample_rate, s
1704 Specify the sample rate, default is 44100.
1707 Specify the duration of the generated audio stream.
1709 @item samples_per_frame
1710 Set the number of samples per output frame, default is 1024.
1713 @subsection Examples
1718 Generate a simple 440 Hz sine wave:
1724 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
1728 sine=frequency=220:beep_factor=4:duration=5
1733 @c man end AUDIO SOURCES
1735 @chapter Audio Sinks
1736 @c man begin AUDIO SINKS
1738 Below is a description of the currently available audio sinks.
1740 @section abuffersink
1742 Buffer audio frames, and make them available to the end of filter chain.
1744 This sink is mainly intended for programmatic use, in particular
1745 through the interface defined in @file{libavfilter/buffersink.h}.
1747 It requires a pointer to an AVABufferSinkContext structure, which
1748 defines the incoming buffers' formats, to be passed as the opaque
1749 parameter to @code{avfilter_init_filter} for initialization.
1753 Null audio sink, do absolutely nothing with the input audio. It is
1754 mainly useful as a template and to be employed in analysis / debugging
1757 @section abuffersink
1758 This sink is intended for programmatic use. Frames that arrive on this sink can
1759 be retrieved by the calling program using the interface defined in
1760 @file{libavfilter/buffersink.h}.
1762 This filter accepts no parameters.
1764 @c man end AUDIO SINKS
1766 @chapter Video Filters
1767 @c man begin VIDEO FILTERS
1769 When you configure your FFmpeg build, you can disable any of the
1770 existing filters using @code{--disable-filters}.
1771 The configure output will show the video filters included in your
1774 Below is a description of the currently available video filters.
1776 @section alphaextract
1778 Extract the alpha component from the input as a grayscale video. This
1779 is especially useful with the @var{alphamerge} filter.
1783 Add or replace the alpha component of the primary input with the
1784 grayscale value of a second input. This is intended for use with
1785 @var{alphaextract} to allow the transmission or storage of frame
1786 sequences that have alpha in a format that doesn't support an alpha
1789 For example, to reconstruct full frames from a normal YUV-encoded video
1790 and a separate video created with @var{alphaextract}, you might use:
1792 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1795 Since this filter is designed for reconstruction, it operates on frame
1796 sequences without considering timestamps, and terminates when either
1797 input reaches end of stream. This will cause problems if your encoding
1798 pipeline drops frames. If you're trying to apply an image as an
1799 overlay to a video stream, consider the @var{overlay} filter instead.
1803 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1804 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1805 Substation Alpha) subtitles files.
1809 Compute the bounding box for the non-black pixels in the input frame
1812 This filter computes the bounding box containing all the pixels with a
1813 luminance value greater than the minimum allowed value.
1814 The parameters describing the bounding box are printed on the filter
1817 @section blackdetect
1819 Detect video intervals that are (almost) completely black. Can be
1820 useful to detect chapter transitions, commercials, or invalid
1821 recordings. Output lines contains the time for the start, end and
1822 duration of the detected black interval expressed in seconds.
1824 In order to display the output lines, you need to set the loglevel at
1825 least to the AV_LOG_INFO value.
1827 This filter accepts a list of options in the form of
1828 @var{key}=@var{value} pairs separated by ":". A description of the
1829 accepted options follows.
1832 @item black_min_duration, d
1833 Set the minimum detected black duration expressed in seconds. It must
1834 be a non-negative floating point number.
1836 Default value is 2.0.
1838 @item picture_black_ratio_th, pic_th
1839 Set the threshold for considering a picture "black".
1840 Express the minimum value for the ratio:
1842 @var{nb_black_pixels} / @var{nb_pixels}
1845 for which a picture is considered black.
1846 Default value is 0.98.
1848 @item pixel_black_th, pix_th
1849 Set the threshold for considering a pixel "black".
1851 The threshold expresses the maximum pixel luminance value for which a
1852 pixel is considered "black". The provided value is scaled according to
1853 the following equation:
1855 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1858 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1859 the input video format, the range is [0-255] for YUV full-range
1860 formats and [16-235] for YUV non full-range formats.
1862 Default value is 0.10.
1865 The following example sets the maximum pixel threshold to the minimum
1866 value, and detects only black intervals of 2 or more seconds:
1868 blackdetect=d=2:pix_th=0.00
1873 Detect frames that are (almost) completely black. Can be useful to
1874 detect chapter transitions or commercials. Output lines consist of
1875 the frame number of the detected frame, the percentage of blackness,
1876 the position in the file if known or -1 and the timestamp in seconds.
1878 In order to display the output lines, you need to set the loglevel at
1879 least to the AV_LOG_INFO value.
1881 The filter accepts parameters as a list of @var{key}=@var{value}
1882 pairs, separated by ":". If the key of the first options is omitted,
1883 the arguments are interpreted according to the syntax
1884 blackframe[=@var{amount}[:@var{threshold}]].
1886 The filter accepts the following options:
1891 The percentage of the pixels that have to be below the threshold, defaults to
1895 Threshold below which a pixel value is considered black, defaults to 32.
1901 Blend two video frames into each other.
1903 It takes two input streams and outputs one stream, the first input is the
1904 "top" layer and second input is "bottom" layer.
1905 Output terminates when shortest input terminates.
1907 This filter accepts a list of options in the form of @var{key}=@var{value}
1908 pairs separated by ":". A description of the accepted options follows.
1916 Set blend mode for specific pixel component or all pixel components in case
1917 of @var{all_mode}. Default value is @code{normal}.
1919 Available values for component modes are:
1952 Set blend opacity for specific pixel component or all pixel components in case
1953 of @var{all_opacity}. Only used in combination with pixel component blend modes.
1960 Set blend expression for specific pixel component or all pixel components in case
1961 of @var{all_expr}. Note that related mode options will be ignored if those are set.
1963 The expressions can use the following variables:
1967 The sequential number of the filtered frame, starting from @code{0}.
1971 the coordinates of the current sample
1975 the width and height of currently filtered plane
1979 Width and height scale depending on the currently filtered plane. It is the
1980 ratio between the corresponding luma plane number of pixels and the current
1981 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
1982 @code{0.5,0.5} for chroma planes.
1985 Time of the current frame, expressed in seconds.
1988 Value of pixel component at current location for first video frame (top layer).
1991 Value of pixel component at current location for second video frame (bottom layer).
1995 @subsection Examples
1999 Apply transition from bottom layer to top layer in first 10 seconds:
2001 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
2005 Apply 1x1 checkerboard effect:
2007 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
2013 Apply boxblur algorithm to the input video.
2015 The filter accepts parameters as a list of @var{key}=@var{value}
2016 pairs, separated by ":". If the key of the first options is omitted,
2017 the arguments are interpreted according to the syntax
2018 @option{luma_radius}:@option{luma_power}:@option{chroma_radius}:@option{chroma_power}:@option{alpha_radius}:@option{alpha_power}.
2020 This filter accepts the following options:
2033 A description of the accepted options follows.
2036 @item luma_radius, lr
2037 @item chroma_radius, cr
2038 @item alpha_radius, ar
2039 Set an expression for the box radius in pixels used for blurring the
2040 corresponding input plane.
2042 The radius value must be a non-negative number, and must not be
2043 greater than the value of the expression @code{min(w,h)/2} for the
2044 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2047 Default value for @option{luma_radius} is "2". If not specified,
2048 @option{chroma_radius} and @option{alpha_radius} default to the
2049 corresponding value set for @option{luma_radius}.
2051 The expressions can contain the following constants:
2054 the input width and height in pixels
2057 the input chroma image width and height in pixels
2060 horizontal and vertical chroma subsample values. For example for the
2061 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2064 @item luma_power, lp
2065 @item chroma_power, cp
2066 @item alpha_power, ap
2067 Specify how many times the boxblur filter is applied to the
2068 corresponding plane.
2070 Default value for @option{luma_power} is 2. If not specified,
2071 @option{chroma_power} and @option{alpha_power} default to the
2072 corresponding value set for @option{luma_power}.
2074 A value of 0 will disable the effect.
2077 @subsection Examples
2081 Apply a boxblur filter with luma, chroma, and alpha radius
2084 boxblur=luma_radius=2:luma_power=1
2089 Set luma radius to 2, alpha and chroma radius to 0:
2091 boxblur=2:1:cr=0:ar=0
2095 Set luma and chroma radius to a fraction of the video dimension:
2097 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
2101 @section colormatrix
2103 Convert color matrix.
2105 The filter accepts the following options:
2110 Specify the source and destination color matrix. Both values must be
2113 The accepted values are:
2129 For example to convert from BT.601 to SMPTE-240M, use the command:
2131 colormatrix=bt601:smpte240m
2136 Copy the input source unchanged to the output. Mainly useful for
2141 Crop the input video to given dimensions.
2143 This filter accepts a list of @var{key}=@var{value} pairs as argument,
2144 separated by ':'. If the key of the first options is omitted, the
2145 arguments are interpreted according to the syntax
2146 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
2148 A description of the accepted options follows:
2151 Width of the output video. It defaults to @code{iw}.
2152 This expression is evaluated only once during the filter
2156 Height of the output video. It defaults to @code{ih}.
2157 This expression is evaluated only once during the filter
2161 Horizontal position, in the input video, of the left edge of the output video.
2162 It defaults to @code{(in_w-out_w)/2}.
2163 This expression is evaluated per-frame.
2166 Vertical position, in the input video, of the top edge of the output video.
2167 It defaults to @code{(in_h-out_h)/2}.
2168 This expression is evaluated per-frame.
2171 If set to 1 will force the output display aspect ratio
2172 to be the same of the input, by changing the output sample aspect
2173 ratio. It defaults to 0.
2176 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2177 expressions containing the following constants:
2181 the computed values for @var{x} and @var{y}. They are evaluated for
2185 the input width and height
2188 same as @var{in_w} and @var{in_h}
2191 the output (cropped) width and height
2194 same as @var{out_w} and @var{out_h}
2197 same as @var{iw} / @var{ih}
2200 input sample aspect ratio
2203 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2206 horizontal and vertical chroma subsample values. For example for the
2207 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2210 the number of input frame, starting from 0
2213 timestamp expressed in seconds, NAN if the input timestamp is unknown
2217 The expression for @var{out_w} may depend on the value of @var{out_h},
2218 and the expression for @var{out_h} may depend on @var{out_w}, but they
2219 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2220 evaluated after @var{out_w} and @var{out_h}.
2222 The @var{x} and @var{y} parameters specify the expressions for the
2223 position of the top-left corner of the output (non-cropped) area. They
2224 are evaluated for each frame. If the evaluated value is not valid, it
2225 is approximated to the nearest valid value.
2227 The expression for @var{x} may depend on @var{y}, and the expression
2228 for @var{y} may depend on @var{x}.
2230 @subsection Examples
2234 Crop area with size 100x100 at position (12,34).
2239 Using named options, the example above becomes:
2241 crop=w=100:h=100:x=12:y=34
2245 Crop the central input area with size 100x100:
2251 Crop the central input area with size 2/3 of the input video:
2253 crop=2/3*in_w:2/3*in_h
2257 Crop the input video central square:
2264 Delimit the rectangle with the top-left corner placed at position
2265 100:100 and the right-bottom corner corresponding to the right-bottom
2266 corner of the input image:
2268 crop=in_w-100:in_h-100:100:100
2272 Crop 10 pixels from the left and right borders, and 20 pixels from
2273 the top and bottom borders
2275 crop=in_w-2*10:in_h-2*20
2279 Keep only the bottom right quarter of the input image:
2281 crop=in_w/2:in_h/2:in_w/2:in_h/2
2285 Crop height for getting Greek harmony:
2287 crop=in_w:1/PHI*in_w
2291 Appply trembling effect:
2293 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)
2297 Apply erratic camera effect depending on timestamp:
2299 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)"
2303 Set x depending on the value of y:
2305 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2311 Auto-detect crop size.
2313 Calculate necessary cropping parameters and prints the recommended
2314 parameters through the logging system. The detected dimensions
2315 correspond to the non-black area of the input video.
2317 The filter accepts parameters as a list of @var{key}=@var{value}
2318 pairs, separated by ":". If the key of the first options is omitted,
2319 the arguments are interpreted according to the syntax
2320 [@option{limit}[:@option{round}[:@option{reset}]]].
2322 A description of the accepted options follows.
2327 Set higher black value threshold, which can be optionally specified
2328 from nothing (0) to everything (255). An intensity value greater
2329 to the set value is considered non-black. Default value is 24.
2332 Set the value for which the width/height should be divisible by. The
2333 offset is automatically adjusted to center the video. Use 2 to get
2334 only even dimensions (needed for 4:2:2 video). 16 is best when
2335 encoding to most video codecs. Default value is 16.
2338 Set the counter that determines after how many frames cropdetect will
2339 reset the previously detected largest video area and start over to
2340 detect the current optimal crop area. Default value is 0.
2342 This can be useful when channel logos distort the video area. 0
2343 indicates never reset and return the largest area encountered during
2349 Apply color adjustments using curves.
2351 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
2352 component (red, green and blue) has its values defined by @var{N} key points
2353 tied from each other using a smooth curve. The x-axis represents the pixel
2354 values from the input frame, and the y-axis the new pixel values to be set for
2357 By default, a component curve is defined by the two points @var{(0;0)} and
2358 @var{(1;1)}. This creates a straight line where each original pixel value is
2359 "adjusted" to its own value, which means no change to the image.
2361 The filter allows you to redefine these two points and add some more. A new
2362 curve (using a natural cubic spline interpolation) will be define to pass
2363 smoothly through all these new coordinates. The new defined points needs to be
2364 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
2365 be in the @var{[0;1]} interval. If the computed curves happened to go outside
2366 the vector spaces, the values will be clipped accordingly.
2368 If there is no key point defined in @code{x=0}, the filter will automatically
2369 insert a @var{(0;0)} point. In the same way, if there is no key point defined
2370 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
2372 The filter accepts the following options:
2376 Select one of the available color presets. This option can not be used in
2377 addition to the @option{r}, @option{g}, @option{b} parameters.
2378 Available presets are:
2381 @item color_negative
2384 @item increase_contrast
2386 @item linear_contrast
2387 @item medium_contrast
2389 @item strong_contrast
2392 Default is @code{none}.
2394 Set the key points for the red component.
2396 Set the key points for the green component.
2398 Set the key points for the blue component.
2400 Set the key points for all components.
2401 Can be used in addition to the other key points component
2402 options. In this case, the unset component(s) will fallback on this
2403 @option{all} setting.
2406 To avoid some filtergraph syntax conflicts, each key points list need to be
2407 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
2409 @subsection Examples
2413 Increase slightly the middle level of blue:
2415 curves=blue='0.5/0.58'
2421 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
2423 Here we obtain the following coordinates for each components:
2426 @code{(0;0.11) (0.42;0.51) (1;0.95)}
2428 @code{(0;0) (0.50;0.48) (1;1)}
2430 @code{(0;0.22) (0.49;0.44) (1;0.80)}
2434 The previous example can also be achieved with the associated built-in preset:
2436 curves=preset=vintage
2448 Drop frames that do not differ greatly from the previous frame in
2449 order to reduce frame rate.
2451 The main use of this filter is for very-low-bitrate encoding
2452 (e.g. streaming over dialup modem), but it could in theory be used for
2453 fixing movies that were inverse-telecined incorrectly.
2455 The filter accepts parameters as a list of @var{key}=@var{value}
2456 pairs, separated by ":". If the key of the first options is omitted,
2457 the arguments are interpreted according to the syntax:
2458 @option{max}:@option{hi}:@option{lo}:@option{frac}.
2460 A description of the accepted options follows.
2464 Set the maximum number of consecutive frames which can be dropped (if
2465 positive), or the minimum interval between dropped frames (if
2466 negative). If the value is 0, the frame is dropped unregarding the
2467 number of previous sequentially dropped frames.
2474 Set the dropping threshold values.
2476 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
2477 represent actual pixel value differences, so a threshold of 64
2478 corresponds to 1 unit of difference for each pixel, or the same spread
2479 out differently over the block.
2481 A frame is a candidate for dropping if no 8x8 blocks differ by more
2482 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
2483 meaning the whole image) differ by more than a threshold of @option{lo}.
2485 Default value for @option{hi} is 64*12, default value for @option{lo} is
2486 64*5, and default value for @option{frac} is 0.33.
2491 Suppress a TV station logo by a simple interpolation of the surrounding
2492 pixels. Just set a rectangle covering the logo and watch it disappear
2493 (and sometimes something even uglier appear - your mileage may vary).
2495 This filter accepts the following options:
2499 Specify the top left corner coordinates of the logo. They must be
2503 Specify the width and height of the logo to clear. They must be
2507 Specify the thickness of the fuzzy edge of the rectangle (added to
2508 @var{w} and @var{h}). The default value is 4.
2511 When set to 1, a green rectangle is drawn on the screen to simplify
2512 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2513 @var{band} is set to 4. The default value is 0.
2517 @subsection Examples
2521 Set a rectangle covering the area with top left corner coordinates 0,0
2522 and size 100x77, setting a band of size 10:
2524 delogo=x=0:y=0:w=100:h=77:band=10
2531 Attempt to fix small changes in horizontal and/or vertical shift. This
2532 filter helps remove camera shake from hand-holding a camera, bumping a
2533 tripod, moving on a vehicle, etc.
2535 The filter accepts parameters as a list of @var{key}=@var{value}
2536 pairs, separated by ":". If the key of the first options is omitted,
2537 the arguments are interpreted according to the syntax
2538 @var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}:@var{opencl}.
2540 A description of the accepted parameters follows.
2545 Specify a rectangular area where to limit the search for motion
2547 If desired the search for motion vectors can be limited to a
2548 rectangular area of the frame defined by its top left corner, width
2549 and height. These parameters have the same meaning as the drawbox
2550 filter which can be used to visualise the position of the bounding
2553 This is useful when simultaneous movement of subjects within the frame
2554 might be confused for camera motion by the motion vector search.
2556 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2557 then the full frame is used. This allows later options to be set
2558 without specifying the bounding box for the motion vector search.
2560 Default - search the whole frame.
2563 Specify the maximum extent of movement in x and y directions in the
2564 range 0-64 pixels. Default 16.
2567 Specify how to generate pixels to fill blanks at the edge of the
2568 frame. Available values are:
2571 Fill zeroes at blank locations
2573 Original image at blank locations
2575 Extruded edge value at blank locations
2577 Mirrored edge at blank locations
2579 Default value is @samp{mirror}.
2582 Specify the blocksize to use for motion search. Range 4-128 pixels,
2586 Specify the contrast threshold for blocks. Only blocks with more than
2587 the specified contrast (difference between darkest and lightest
2588 pixels) will be considered. Range 1-255, default 125.
2591 Specify the search strategy. Available values are:
2594 Set exhaustive search
2596 Set less exhaustive search.
2598 Default value is @samp{exhaustive}.
2601 If set then a detailed log of the motion search is written to the
2605 If set to 1, specify using OpenCL capabilities, only available if
2606 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
2612 Draw a colored box on the input image.
2614 This filter accepts the following options:
2618 Specify the top left corner coordinates of the box. Default to 0.
2622 Specify the width and height of the box, if 0 they are interpreted as
2623 the input width and height. Default to 0.
2626 Specify the color of the box to write, it can be the name of a color
2627 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2628 value @code{invert} is used, the box edge color is the same as the
2629 video with inverted luma.
2632 Set the thickness of the box edge. Default value is @code{4}.
2635 @subsection Examples
2639 Draw a black box around the edge of the input image:
2645 Draw a box with color red and an opacity of 50%:
2647 drawbox=10:20:200:60:red@@0.5
2650 The previous example can be specified as:
2652 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2656 Fill the box with pink color:
2658 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2665 Draw text string or text from specified file on top of video using the
2666 libfreetype library.
2668 To enable compilation of this filter you need to configure FFmpeg with
2669 @code{--enable-libfreetype}.
2673 The description of the accepted parameters follows.
2678 Used to draw a box around text using background color.
2679 Value should be either 1 (enable) or 0 (disable).
2680 The default value of @var{box} is 0.
2683 The color to be used for drawing box around text.
2684 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2685 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2686 The default value of @var{boxcolor} is "white".
2689 Set an expression which specifies if the text should be drawn. If the
2690 expression evaluates to 0, the text is not drawn. This is useful for
2691 specifying that the text should be drawn only when specific conditions
2694 Default value is "1".
2696 See below for the list of accepted constants and functions.
2699 Select how the @var{text} is expanded. Can be either @code{none},
2700 @code{strftime} (deprecated) or
2701 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2705 If true, check and fix text coords to avoid clipping.
2708 The color to be used for drawing fonts.
2709 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2710 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2711 The default value of @var{fontcolor} is "black".
2714 The font file to be used for drawing text. Path must be included.
2715 This parameter is mandatory.
2718 The font size to be used for drawing text.
2719 The default value of @var{fontsize} is 16.
2722 Flags to be used for loading the fonts.
2724 The flags map the corresponding flags supported by libfreetype, and are
2725 a combination of the following values:
2732 @item vertical_layout
2733 @item force_autohint
2736 @item ignore_global_advance_width
2738 @item ignore_transform
2745 Default value is "render".
2747 For more information consult the documentation for the FT_LOAD_*
2751 The color to be used for drawing a shadow behind the drawn text. It
2752 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2753 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2754 The default value of @var{shadowcolor} is "black".
2756 @item shadowx, shadowy
2757 The x and y offsets for the text shadow position with respect to the
2758 position of the text. They can be either positive or negative
2759 values. Default value for both is "0".
2762 The size in number of spaces to use for rendering the tab.
2766 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2767 format. It can be used with or without text parameter. @var{timecode_rate}
2768 option must be specified.
2770 @item timecode_rate, rate, r
2771 Set the timecode frame rate (timecode only).
2774 The text string to be drawn. The text must be a sequence of UTF-8
2776 This parameter is mandatory if no file is specified with the parameter
2780 A text file containing text to be drawn. The text must be a sequence
2781 of UTF-8 encoded characters.
2783 This parameter is mandatory if no text string is specified with the
2784 parameter @var{text}.
2786 If both @var{text} and @var{textfile} are specified, an error is thrown.
2789 If set to 1, the @var{textfile} will be reloaded before each frame.
2790 Be sure to update it atomically, or it may be read partially, or even fail.
2793 The expressions which specify the offsets where text will be drawn
2794 within the video frame. They are relative to the top/left border of the
2797 The default value of @var{x} and @var{y} is "0".
2799 See below for the list of accepted constants and functions.
2802 The parameters for @var{x} and @var{y} are expressions containing the
2803 following constants and functions:
2807 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2810 horizontal and vertical chroma subsample values. For example for the
2811 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2814 the height of each text line
2822 @item max_glyph_a, ascent
2823 the maximum distance from the baseline to the highest/upper grid
2824 coordinate used to place a glyph outline point, for all the rendered
2826 It is a positive value, due to the grid's orientation with the Y axis
2829 @item max_glyph_d, descent
2830 the maximum distance from the baseline to the lowest grid coordinate
2831 used to place a glyph outline point, for all the rendered glyphs.
2832 This is a negative value, due to the grid's orientation, with the Y axis
2836 maximum glyph height, that is the maximum height for all the glyphs
2837 contained in the rendered text, it is equivalent to @var{ascent} -
2841 maximum glyph width, that is the maximum width for all the glyphs
2842 contained in the rendered text
2845 the number of input frame, starting from 0
2847 @item rand(min, max)
2848 return a random number included between @var{min} and @var{max}
2851 input sample aspect ratio
2854 timestamp expressed in seconds, NAN if the input timestamp is unknown
2857 the height of the rendered text
2860 the width of the rendered text
2863 the x and y offset coordinates where the text is drawn.
2865 These parameters allow the @var{x} and @var{y} expressions to refer
2866 each other, so you can for example specify @code{y=x/dar}.
2869 If libavfilter was built with @code{--enable-fontconfig}, then
2870 @option{fontfile} can be a fontconfig pattern or omitted.
2872 @anchor{drawtext_expansion}
2873 @subsection Text expansion
2875 If @option{expansion} is set to @code{strftime},
2876 the filter recognizes strftime() sequences in the provided text and
2877 expands them accordingly. Check the documentation of strftime(). This
2878 feature is deprecated.
2880 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2882 If @option{expansion} is set to @code{normal} (which is the default),
2883 the following expansion mechanism is used.
2885 The backslash character '\', followed by any character, always expands to
2886 the second character.
2888 Sequence of the form @code{%@{...@}} are expanded. The text between the
2889 braces is a function name, possibly followed by arguments separated by ':'.
2890 If the arguments contain special characters or delimiters (':' or '@}'),
2891 they should be escaped.
2893 Note that they probably must also be escaped as the value for the
2894 @option{text} option in the filter argument string and as the filter
2895 argument in the filtergraph description, and possibly also for the shell,
2896 that makes up to four levels of escaping; using a text file avoids these
2899 The following functions are available:
2904 The expression evaluation result.
2906 It must take one argument specifying the expression to be evaluated,
2907 which accepts the same constants and functions as the @var{x} and
2908 @var{y} values. Note that not all constants should be used, for
2909 example the text size is not known when evaluating the expression, so
2910 the constants @var{text_w} and @var{text_h} will have an undefined
2914 The time at which the filter is running, expressed in UTC.
2915 It can accept an argument: a strftime() format string.
2918 The time at which the filter is running, expressed in the local time zone.
2919 It can accept an argument: a strftime() format string.
2922 The frame number, starting from 0.
2925 The timestamp of the current frame, in seconds, with microsecond accuracy.
2929 @subsection Examples
2933 Draw "Test Text" with font FreeSerif, using the default values for the
2934 optional parameters.
2937 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2941 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2942 and y=50 (counting from the top-left corner of the screen), text is
2943 yellow with a red box around it. Both the text and the box have an
2947 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2948 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2951 Note that the double quotes are not necessary if spaces are not used
2952 within the parameter list.
2955 Show the text at the center of the video frame:
2957 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2961 Show a text line sliding from right to left in the last row of the video
2962 frame. The file @file{LONG_LINE} is assumed to contain a single line
2965 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2969 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2971 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2975 Draw a single green letter "g", at the center of the input video.
2976 The glyph baseline is placed at half screen height.
2978 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2982 Show text for 1 second every 3 seconds:
2984 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2988 Use fontconfig to set the font. Note that the colons need to be escaped.
2990 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2994 Print the date of a real-time encoding (see strftime(3)):
2996 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
3001 For more information about libfreetype, check:
3002 @url{http://www.freetype.org/}.
3004 For more information about fontconfig, check:
3005 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3009 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3011 The filter accepts the following options:
3015 Set low and high threshold values used by the Canny thresholding
3018 The high threshold selects the "strong" edge pixels, which are then
3019 connected through 8-connectivity with the "weak" edge pixels selected
3020 by the low threshold.
3022 @var{low} and @var{high} threshold values must be choosen in the range
3023 [0,1], and @var{low} should be lesser or equal to @var{high}.
3025 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3031 edgedetect=low=0.1:high=0.4
3036 Apply fade-in/out effect to input video.
3038 This filter accepts the following options:
3042 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3044 Default is @code{in}.
3046 @item start_frame, s
3047 Specify the number of the start frame for starting to apply the fade
3048 effect. Default is 0.
3051 The number of frames for which the fade effect has to last. At the end of the
3052 fade-in effect the output video will have the same intensity as the input video,
3053 at the end of the fade-out transition the output video will be completely black.
3057 If set to 1, fade only alpha channel, if one exists on the input.
3061 @subsection Examples
3065 Fade in first 30 frames of video:
3070 The command above is equivalent to:
3076 Fade out last 45 frames of a 200-frame video:
3079 fade=type=out:start_frame=155:nb_frames=45
3083 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
3085 fade=in:0:25, fade=out:975:25
3089 Make first 5 frames black, then fade in from frame 5-24:
3095 Fade in alpha over first 25 frames of video:
3097 fade=in:0:25:alpha=1
3103 Extract a single field from an interlaced image using stride
3104 arithmetic to avoid wasting CPU time. The output frames are marked as
3107 This filter accepts the following named options:
3110 Specify whether to extract the top (if the value is @code{0} or
3111 @code{top}) or the bottom field (if the value is @code{1} or
3115 If the option key is not specified, the first value sets the @var{type}
3116 option. For example:
3128 Transform the field order of the input video.
3130 This filter accepts the following options:
3135 Output field order. Valid values are @var{tff} for top field first or @var{bff}
3136 for bottom field first.
3139 Default value is @samp{tff}.
3141 Transformation is achieved by shifting the picture content up or down
3142 by one line, and filling the remaining line with appropriate picture content.
3143 This method is consistent with most broadcast field order converters.
3145 If the input video is not flagged as being interlaced, or it is already
3146 flagged as being of the required output field order then this filter does
3147 not alter the incoming video.
3149 This filter is very useful when converting to or from PAL DV material,
3150 which is bottom field first.
3154 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
3159 Buffer input images and send them when they are requested.
3161 This filter is mainly useful when auto-inserted by the libavfilter
3164 The filter does not take parameters.
3169 Convert the input video to one of the specified pixel formats.
3170 Libavfilter will try to pick one that is supported for the input to
3173 This filter accepts the following parameters:
3177 A '|'-separated list of pixel format names, for example
3178 "pix_fmts=yuv420p|monow|rgb24".
3182 @subsection Examples
3186 Convert the input video to the format @var{yuv420p}
3188 format=pix_fmts=yuv420p
3191 Convert the input video to any of the formats in the list
3193 format=pix_fmts=yuv420p|yuv444p|yuv410p
3199 Convert the video to specified constant frame rate by duplicating or dropping
3200 frames as necessary.
3202 This filter accepts the following named parameters:
3206 Desired output frame rate. The default is @code{25}.
3211 Possible values are:
3214 zero round towards 0
3218 round towards -infinity
3220 round towards +infinity
3224 The default is @code{near}.
3228 Alternatively, the options can be specified as a flat string:
3229 @var{fps}[:@var{round}].
3231 See also the @ref{setpts} filter.
3235 Select one frame every N.
3237 This filter accepts in input a string representing a positive
3238 integer. Default argument is @code{1}.
3243 Apply a frei0r effect to the input video.
3245 To enable compilation of this filter you need to install the frei0r
3246 header and configure FFmpeg with @code{--enable-frei0r}.
3248 This filter accepts the following options:
3253 The name to the frei0r effect to load. If the environment variable
3254 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
3255 directories specified by the colon separated list in @env{FREIOR_PATH},
3256 otherwise in the standard frei0r paths, which are in this order:
3257 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3258 @file{/usr/lib/frei0r-1/}.
3261 A '|'-separated list of parameters to pass to the frei0r effect.
3265 A frei0r effect parameter can be a boolean (whose values are specified
3266 with "y" and "n"), a double, a color (specified by the syntax
3267 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3268 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3269 description), a position (specified by the syntax @var{X}/@var{Y},
3270 @var{X} and @var{Y} being float numbers) and a string.
3272 The number and kind of parameters depend on the loaded effect. If an
3273 effect parameter is not specified the default value is set.
3275 @subsection Examples
3279 Apply the distort0r effect, set the first two double parameters:
3281 frei0r=filter_name=distort0r:filter_params=0.5|0.01
3285 Apply the colordistance effect, take a color as first parameter:
3287 frei0r=colordistance:0.2/0.3/0.4
3288 frei0r=colordistance:violet
3289 frei0r=colordistance:0x112233
3293 Apply the perspective effect, specify the top left and top right image
3296 frei0r=perspective:0.2/0.2|0.8/0.2
3300 For more information see:
3301 @url{http://frei0r.dyne.org}
3305 The filter accepts the following options:
3309 the luminance expression
3311 the chrominance blue expression
3313 the chrominance red expression
3315 the alpha expression
3318 If one of the chrominance expression is not defined, it falls back on the other
3319 one. If no alpha expression is specified it will evaluate to opaque value.
3320 If none of chrominance expressions are
3321 specified, they will evaluate the luminance expression.
3323 The expressions can use the following variables and functions:
3327 The sequential number of the filtered frame, starting from @code{0}.
3331 The coordinates of the current sample.
3335 The width and height of the image.
3339 Width and height scale depending on the currently filtered plane. It is the
3340 ratio between the corresponding luma plane number of pixels and the current
3341 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3342 @code{0.5,0.5} for chroma planes.
3345 Time of the current frame, expressed in seconds.
3348 Return the value of the pixel at location (@var{x},@var{y}) of the current
3352 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3356 Return the value of the pixel at location (@var{x},@var{y}) of the
3357 blue-difference chroma plane. Returns 0 if there is no such plane.
3360 Return the value of the pixel at location (@var{x},@var{y}) of the
3361 red-difference chroma plane. Returns 0 if there is no such plane.
3364 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
3365 plane. Returns 0 if there is no such plane.
3368 For functions, if @var{x} and @var{y} are outside the area, the value will be
3369 automatically clipped to the closer edge.
3371 @subsection Examples
3375 Flip the image horizontally:
3381 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3382 wavelength of 100 pixels:
3384 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3388 Generate a fancy enigmatic moving light:
3390 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
3396 Fix the banding artifacts that are sometimes introduced into nearly flat
3397 regions by truncation to 8bit color depth.
3398 Interpolate the gradients that should go where the bands are, and
3401 This filter is designed for playback only. Do not use it prior to
3402 lossy compression, because compression tends to lose the dither and
3403 bring back the bands.
3405 This filter accepts the following options:
3410 The maximum amount by which the filter will change any one pixel. Also the
3411 threshold for detecting nearly flat regions. Acceptable values range from .51 to
3412 64, default value is 1.2, out-of-range values will be clipped to the valid
3416 The neighborhood to fit the gradient to. A larger radius makes for smoother
3417 gradients, but also prevents the filter from modifying the pixels near detailed
3418 regions. Acceptable values are 8-32, default value is 16, out-of-range values
3419 will be clipped to the valid range.
3423 Alternatively, the options can be specified as a flat string:
3424 @var{strength}[:@var{radius}]
3426 @subsection Examples
3430 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3436 Specify radius, omitting the strength (which will fall-back to the default
3446 Flip the input video horizontally.
3448 For example to horizontally flip the input video with @command{ffmpeg}:
3450 ffmpeg -i in.avi -vf "hflip" out.avi
3454 This filter applies a global color histogram equalization on a
3457 It can be used to correct video that has a compressed range of pixel
3458 intensities. The filter redistributes the pixel intensities to
3459 equalize their distribution across the intensity range. It may be
3460 viewed as an "automatically adjusting contrast filter". This filter is
3461 useful only for correcting degraded or poorly captured source
3464 The filter accepts parameters as a list of @var{key}=@var{value}
3465 pairs, separated by ":". If the key of the first options is omitted,
3466 the arguments are interpreted according to syntax
3467 @var{strength}:@var{intensity}:@var{antibanding}.
3469 This filter accepts the following named options:
3473 Determine the amount of equalization to be applied. As the strength
3474 is reduced, the distribution of pixel intensities more-and-more
3475 approaches that of the input frame. The value must be a float number
3476 in the range [0,1] and defaults to 0.200.
3479 Set the maximum intensity that can generated and scale the output
3480 values appropriately. The strength should be set as desired and then
3481 the intensity can be limited if needed to avoid washing-out. The value
3482 must be a float number in the range [0,1] and defaults to 0.210.
3485 Set the antibanding level. If enabled the filter will randomly vary
3486 the luminance of output pixels by a small amount to avoid banding of
3487 the histogram. Possible values are @code{none}, @code{weak} or
3488 @code{strong}. It defaults to @code{none}.
3493 Compute and draw a color distribution histogram for the input video.
3495 The computed histogram is a representation of distribution of color components
3498 The filter accepts the following named parameters:
3504 It accepts the following values:
3507 standard histogram that display color components distribution in an image.
3508 Displays color graph for each color component. Shows distribution
3509 of the Y, U, V, A or G, B, R components, depending on input format,
3510 in current frame. Bellow each graph is color component scale meter.
3513 chroma values in vectorscope, if brighter more such chroma values are
3514 distributed in an image.
3515 Displays chroma values (U/V color placement) in two dimensional graph
3516 (which is called a vectorscope). It can be used to read of the hue and
3517 saturation of the current frame. At a same time it is a histogram.
3518 The whiter a pixel in the vectorscope, the more pixels of the input frame
3519 correspond to that pixel (that is the more pixels have this chroma value).
3520 The V component is displayed on the horizontal (X) axis, with the leftmost
3521 side being V = 0 and the rightmost side being V = 255.
3522 The U component is displayed on the vertical (Y) axis, with the top
3523 representing U = 0 and the bottom representing U = 255.
3525 The position of a white pixel in the graph corresponds to the chroma value
3526 of a pixel of the input clip. So the graph can be used to read of the
3527 hue (color flavor) and the saturation (the dominance of the hue in the color).
3528 As the hue of a color changes, it moves around the square. At the center of
3529 the square, the saturation is zero, which means that the corresponding pixel
3530 has no color. If you increase the amount of a specific color, while leaving
3531 the other colors unchanged, the saturation increases, and you move towards
3532 the edge of the square.
3535 chroma values in vectorscope, similar as @code{color} but actual chroma values
3539 per row/column color component graph. In row mode graph in the left side represents
3540 color component value 0 and right side represents value = 255. In column mode top
3541 side represents color component value = 0 and bottom side represents value = 255.
3543 Default value is @code{levels}.
3546 Set height of level in @code{levels}. Default value is @code{200}.
3547 Allowed range is [50, 2048].
3550 Set height of color scale in @code{levels}. Default value is @code{12}.
3551 Allowed range is [0, 40].
3554 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3555 of same luminance values across input rows/columns are distributed.
3556 Default value is @code{10}. Allowed range is [1, 255].
3559 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3560 Default is @code{row}.
3563 Set display mode for @code{waveform} and @code{levels}.
3564 It accepts the following values:
3567 Display separate graph for the color components side by side in
3568 @code{row} waveform mode or one below other in @code{column} waveform mode
3569 for @code{waveform} histogram mode. For @code{levels} histogram mode
3570 per color component graphs are placed one bellow other.
3572 This display mode in @code{waveform} histogram mode makes it easy to spot
3573 color casts in the highlights and shadows of an image, by comparing the
3574 contours of the top and the bottom of each waveform.
3575 Since whites, grays, and blacks are characterized by
3576 exactly equal amounts of red, green, and blue, neutral areas of the
3577 picture should display three waveforms of roughly equal width/height.
3578 If not, the correction is easy to make by making adjustments to level the
3582 Presents information that's identical to that in the @code{parade}, except
3583 that the graphs representing color components are superimposed directly
3586 This display mode in @code{waveform} histogram mode can make it easier to spot
3587 the relative differences or similarities in overlapping areas of the color
3588 components that are supposed to be identical, such as neutral whites, grays,
3591 Default is @code{parade}.
3594 @subsection Examples
3599 Calculate and draw histogram:
3601 ffplay -i input -vf histogram
3608 High precision/quality 3d denoise filter. This filter aims to reduce
3609 image noise producing smooth images and making still images really
3610 still. It should enhance compressibility.
3612 It accepts the following optional parameters:
3616 a non-negative float number which specifies spatial luma strength,
3619 @item chroma_spatial
3620 a non-negative float number which specifies spatial chroma strength,
3621 defaults to 3.0*@var{luma_spatial}/4.0
3624 a float number which specifies luma temporal strength, defaults to
3625 6.0*@var{luma_spatial}/4.0
3628 a float number which specifies chroma temporal strength, defaults to
3629 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3634 Modify the hue and/or the saturation of the input.
3636 This filter accepts the following optional named options:
3640 Specify the hue angle as a number of degrees. It accepts a float
3641 number or an expression, and defaults to 0.0.
3644 Specify the hue angle as a number of radians. It accepts a float
3645 number or an expression, and defaults to 0.0.
3648 Specify the saturation in the [-10,10] range. It accepts a float number and
3652 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3653 following constants:
3657 frame count of the input frame starting from 0
3660 presentation timestamp of the input frame expressed in time base units
3663 frame rate of the input video, NAN if the input frame rate is unknown
3666 timestamp expressed in seconds, NAN if the input timestamp is unknown
3669 time base of the input video
3672 The options can also be set using the syntax: @var{hue}:@var{saturation}
3674 In this case @var{hue} is expressed in degrees.
3676 @subsection Examples
3680 Set the hue to 90 degrees and the saturation to 1.0:
3686 Same command but expressing the hue in radians:
3692 Same command without named options, hue must be expressed in degrees:
3698 Note that "h:s" syntax does not support expressions for the values of
3699 h and s, so the following example will issue an error:
3705 Rotate hue and make the saturation swing between 0
3706 and 2 over a period of 1 second:
3708 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3712 Apply a 3 seconds saturation fade-in effect starting at 0:
3717 The general fade-in expression can be written as:
3719 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3723 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3725 hue="s=max(0\, min(1\, (8-t)/3))"
3728 The general fade-out expression can be written as:
3730 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3735 @subsection Commands
3737 This filter supports the following command:
3740 Modify the hue and/or the saturation of the input video.
3741 The command accepts the same named options and syntax than when calling the
3742 filter from the command-line.
3744 If a parameter is omitted, it is kept at its current value.
3749 Detect video interlacing type.
3751 This filter tries to detect if the input is interlaced or progressive,
3752 top or bottom field first.
3756 Deinterleave or interleave fields.
3758 This filter allows to process interlaced images fields without
3759 deinterlacing them. Deinterleaving splits the input frame into 2
3760 fields (so called half pictures). Odd lines are moved to the top
3761 half of the output image, even lines to the bottom half.
3762 You can process (filter) them independently and then re-interleave them.
3764 It accepts a list of options in the form of @var{key}=@var{value} pairs
3765 separated by ":". A description of the accepted options follows.
3769 @item chroma_mode, s
3771 Available values for @var{luma_mode}, @var{chroma_mode} and
3772 @var{alpha_mode} are:
3778 @item deinterleave, d
3779 Deinterleave fields, placing one above the other.
3782 Interleave fields. Reverse the effect of deinterleaving.
3784 Default value is @code{none}.
3787 @item chroma_swap, cs
3788 @item alpha_swap, as
3789 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3794 Deinterlace input video by applying Donald Graft's adaptive kernel
3795 deinterling. Work on interlaced parts of a video to produce
3798 This filter accepts parameters as a list of @var{key}=@var{value}
3799 pairs, separated by ":". If the key of the first options is omitted,
3800 the arguments are interpreted according to the following syntax:
3801 @var{thresh}:@var{map}:@var{order}:@var{sharp}:@var{twoway}.
3803 The description of the accepted parameters follows.
3807 Set the threshold which affects the filter's tolerance when
3808 determining if a pixel line must be processed. It must be an integer
3809 in the range [0,255] and defaults to 10. A value of 0 will result in
3810 applying the process on every pixels.
3813 Paint pixels exceeding the threshold value to white if set to 1.
3817 Set the fields order. Swap fields if set to 1, leave fields alone if
3821 Enable additional sharpening if set to 1. Default is 0.
3824 Enable twoway sharpening if set to 1. Default is 0.
3827 @subsection Examples
3831 Apply default values:
3833 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3837 Enable additional sharpening:
3843 Paint processed pixels in white:
3849 @section lut, lutrgb, lutyuv
3851 Compute a look-up table for binding each pixel component input value
3852 to an output value, and apply it to input video.
3854 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3855 to an RGB input video.
3857 These filters accept the following options:
3860 set first pixel component expression
3862 set second pixel component expression
3864 set third pixel component expression
3866 set fourth pixel component expression, corresponds to the alpha component
3869 set red component expression
3871 set green component expression
3873 set blue component expression
3875 alpha component expression
3878 set Y/luminance component expression
3880 set U/Cb component expression
3882 set V/Cr component expression
3885 Each of them specifies the expression to use for computing the lookup table for
3886 the corresponding pixel component values.
3888 The exact component associated to each of the @var{c*} options depends on the
3891 The @var{lut} filter requires either YUV or RGB pixel formats in input,
3892 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
3894 The expressions can contain the following constants and functions:
3898 the input width and height
3901 input value for the pixel component
3904 the input value clipped in the @var{minval}-@var{maxval} range
3907 maximum value for the pixel component
3910 minimum value for the pixel component
3913 the negated value for the pixel component value clipped in the
3914 @var{minval}-@var{maxval} range , it corresponds to the expression
3915 "maxval-clipval+minval"
3918 the computed value in @var{val} clipped in the
3919 @var{minval}-@var{maxval} range
3921 @item gammaval(gamma)
3922 the computed gamma correction value of the pixel component value
3923 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3925 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3929 All expressions default to "val".
3931 @subsection Examples
3937 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3938 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3941 The above is the same as:
3943 lutrgb="r=negval:g=negval:b=negval"
3944 lutyuv="y=negval:u=negval:v=negval"
3954 Remove chroma components, turns the video into a graytone image:
3956 lutyuv="u=128:v=128"
3960 Apply a luma burning effect:
3966 Remove green and blue components:
3972 Set a constant alpha channel value on input:
3974 format=rgba,lutrgb=a="maxval-minval/2"
3978 Correct luminance gamma by a 0.5 factor:
3980 lutyuv=y=gammaval(0.5)
3984 Discard least significant bits of luma:
3986 lutyuv=y='bitand(val, 128+64+32)'
3992 Apply an MPlayer filter to the input video.
3994 This filter provides a wrapper around most of the filters of
3997 This wrapper is considered experimental. Some of the wrapped filters
3998 may not work properly and we may drop support for them, as they will
3999 be implemented natively into FFmpeg. Thus you should avoid
4000 depending on them when writing portable scripts.
4002 The filters accepts the parameters:
4003 @var{filter_name}[:=]@var{filter_params}
4005 @var{filter_name} is the name of a supported MPlayer filter,
4006 @var{filter_params} is a string containing the parameters accepted by
4009 The list of the currently supported filters follows:
4036 The parameter syntax and behavior for the listed filters are the same
4037 of the corresponding MPlayer filters. For detailed instructions check
4038 the "VIDEO FILTERS" section in the MPlayer manual.
4040 @subsection Examples
4044 Adjust gamma, brightness, contrast:
4050 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
4056 This filter accepts an integer in input, if non-zero it negates the
4057 alpha component (if available). The default value in input is 0.
4061 Force libavfilter not to use any of the specified pixel formats for the
4062 input to the next filter.
4064 This filter accepts the following parameters:
4068 A '|'-separated list of pixel format names, for example
4069 "pix_fmts=yuv420p|monow|rgb24".
4073 @subsection Examples
4077 Force libavfilter to use a format different from @var{yuv420p} for the
4078 input to the vflip filter:
4080 noformat=pix_fmts=yuv420p,vflip
4084 Convert the input video to any of the formats not contained in the list:
4086 noformat=yuv420p|yuv444p|yuv410p
4092 Add noise on video input frame.
4094 This filter accepts a list of options in the form of @var{key}=@var{value}
4095 pairs separated by ":". A description of the accepted options follows.
4103 Set noise seed for specific pixel component or all pixel components in case
4104 of @var{all_seed}. Default value is @code{123457}.
4106 @item all_strength, alls
4107 @item c0_strength, c0s
4108 @item c1_strength, c1s
4109 @item c2_strength, c2s
4110 @item c3_strength, c3s
4111 Set noise strength for specific pixel component or all pixel components in case
4112 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
4114 @item all_flags, allf
4119 Set pixel component flags or set flags for all components if @var{all_flags}.
4120 Available values for component flags are:
4123 averaged temporal noise (smoother)
4125 mix random noise with a (semi)regular pattern
4127 higher quality (slightly better looking, slightly slower)
4129 temporal noise (noise pattern changes between frames)
4131 uniform noise (gaussian otherwise)
4135 @subsection Examples
4137 Add temporal and uniform noise to input video:
4139 noise=alls=20:allf=t+u
4144 Pass the video source unchanged to the output.
4148 Apply video transform using libopencv.
4150 To enable this filter install libopencv library and headers and
4151 configure FFmpeg with @code{--enable-libopencv}.
4153 This filter accepts the following parameters:
4158 The name of the libopencv filter to apply.
4161 The parameters to pass to the libopencv filter. If not specified the default
4166 Refer to the official libopencv documentation for more precise
4168 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
4170 Follows the list of supported libopencv filters.
4175 Dilate an image by using a specific structuring element.
4176 This filter corresponds to the libopencv function @code{cvDilate}.
4178 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
4180 @var{struct_el} represents a structuring element, and has the syntax:
4181 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
4183 @var{cols} and @var{rows} represent the number of columns and rows of
4184 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
4185 point, and @var{shape} the shape for the structuring element, and
4186 can be one of the values "rect", "cross", "ellipse", "custom".
4188 If the value for @var{shape} is "custom", it must be followed by a
4189 string of the form "=@var{filename}". The file with name
4190 @var{filename} is assumed to represent a binary image, with each
4191 printable character corresponding to a bright pixel. When a custom
4192 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
4193 or columns and rows of the read file are assumed instead.
4195 The default value for @var{struct_el} is "3x3+0x0/rect".
4197 @var{nb_iterations} specifies the number of times the transform is
4198 applied to the image, and defaults to 1.
4200 Follow some example:
4202 # use the default values
4205 # dilate using a structuring element with a 5x5 cross, iterate two times
4206 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
4208 # read the shape from the file diamond.shape, iterate two times
4209 # the file diamond.shape may contain a pattern of characters like this:
4215 # the specified cols and rows are ignored (but not the anchor point coordinates)
4216 ocv=dilate:0x0+2x2/custom=diamond.shape|2
4221 Erode an image by using a specific structuring element.
4222 This filter corresponds to the libopencv function @code{cvErode}.
4224 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4225 with the same syntax and semantics as the @ref{dilate} filter.
4229 Smooth the input video.
4231 The filter takes the following parameters:
4232 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
4234 @var{type} is the type of smooth filter to apply, and can be one of
4235 the following values: "blur", "blur_no_scale", "median", "gaussian",
4236 "bilateral". The default value is "gaussian".
4238 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
4239 parameters whose meanings depend on smooth type. @var{param1} and
4240 @var{param2} accept integer positive values or 0, @var{param3} and
4241 @var{param4} accept float values.
4243 The default value for @var{param1} is 3, the default value for the
4244 other parameters is 0.
4246 These parameters correspond to the parameters assigned to the
4247 libopencv function @code{cvSmooth}.
4252 Overlay one video on top of another.
4254 It takes two inputs and one output, the first input is the "main"
4255 video on which the second input is overlayed.
4257 This filter accepts the following parameters:
4259 A description of the accepted options follows.
4264 Set the expression for the x and y coordinates of the overlayed video
4265 on the main video. Default value is "0" for both expressions. In case
4266 the expression is invalid, it is set to a huge value (meaning that the
4267 overlay will not be displayed within the output visible area).
4270 Set the expression which enables the overlay. If the evaluation is
4271 different from 0, the overlay is displayed on top of the input
4272 frame. By default it is "1".
4275 Set when the expressions for @option{x}, @option{y}, and
4276 @option{enable} are evaluated.
4278 It accepts the following values:
4281 only evaluate expressions once during the filter initialization or
4282 when a command is processed
4285 evaluate expressions for each incoming frame
4288 Default value is @samp{frame}.
4291 If set to 1, force the output to terminate when the shortest input
4292 terminates. Default value is 0.
4295 Set the format for the output video.
4297 It accepts the following values:
4309 Default value is @samp{yuv420}.
4311 @item rgb @emph{(deprecated)}
4312 If set to 1, force the filter to accept inputs in the RGB
4313 color space. Default value is 0. This option is deprecated, use
4314 @option{format} instead.
4317 The @option{x}, @option{y}, and @option{enable} expressions can
4318 contain the following parameters.
4323 main input width and height
4327 overlay input width and height
4331 the computed values for @var{x} and @var{y}. They are evaluated for
4336 horizontal and vertical chroma subsample values of the output
4337 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
4341 the number of input frame, starting from 0
4344 the position in the file of the input frame, NAN if unknown
4347 timestamp expressed in seconds, NAN if the input timestamp is unknown
4350 Note that the @var{n}, @var{pos}, @var{t} variables are available only
4351 when evaluation is done @emph{per frame}, and will evaluate to NAN
4352 when @option{eval} is set to @samp{init}.
4354 Be aware that frames are taken from each input video in timestamp
4355 order, hence, if their initial timestamps differ, it is a a good idea
4356 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4357 have them begin in the same zero timestamp, as it does the example for
4358 the @var{movie} filter.
4360 You can chain together more overlays but you should test the
4361 efficiency of such approach.
4363 @subsection Commands
4365 This filter supports the following command:
4368 Set the @option{x} option expression.
4371 Set the @option{y} option expression.
4374 Set the @option{enable} option expression.
4377 @subsection Examples
4381 Draw the overlay at 10 pixels from the bottom right corner of the main
4384 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4387 Using named options the example above becomes:
4389 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4393 Insert a transparent PNG logo in the bottom left corner of the input,
4394 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4396 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4400 Insert 2 different transparent PNG logos (second logo on bottom
4401 right corner) using the @command{ffmpeg} tool:
4403 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
4407 Add a transparent color layer on top of the main video, @code{WxH}
4408 must specify the size of the main input to the overlay filter:
4410 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
4414 Play an original video and a filtered version (here with the deshake
4415 filter) side by side using the @command{ffplay} tool:
4417 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4420 The above command is the same as:
4422 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4426 Make a sliding overlay appearing from the left to the right top part of the
4427 screen starting since time 2:
4429 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
4433 Compose output by putting two input videos side to side:
4435 ffmpeg -i left.avi -i right.avi -filter_complex "
4436 nullsrc=size=200x100 [background];
4437 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4438 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4439 [background][left] overlay=shortest=1 [background+left];
4440 [background+left][right] overlay=shortest=1:x=100 [left+right]
4445 Chain several overlays in cascade:
4447 nullsrc=s=200x200 [bg];
4448 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4449 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4450 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4451 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4452 [in3] null, [mid2] overlay=100:100 [out0]
4459 Add paddings to the input image, and place the original input at the
4460 given coordinates @var{x}, @var{y}.
4462 This filter accepts the following parameters:
4467 Specify an expression for the size of the output image with the
4468 paddings added. If the value for @var{width} or @var{height} is 0, the
4469 corresponding input size is used for the output.
4471 The @var{width} expression can reference the value set by the
4472 @var{height} expression, and vice versa.
4474 The default value of @var{width} and @var{height} is 0.
4478 Specify an expression for the offsets where to place the input image
4479 in the padded area with respect to the top/left border of the output
4482 The @var{x} expression can reference the value set by the @var{y}
4483 expression, and vice versa.
4485 The default value of @var{x} and @var{y} is 0.
4488 Specify the color of the padded area, it can be the name of a color
4489 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4491 The default value of @var{color} is "black".
4494 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4495 options are expressions containing the following constants:
4499 the input video width and height
4502 same as @var{in_w} and @var{in_h}
4505 the output width and height, that is the size of the padded area as
4506 specified by the @var{width} and @var{height} expressions
4509 same as @var{out_w} and @var{out_h}
4512 x and y offsets as specified by the @var{x} and @var{y}
4513 expressions, or NAN if not yet specified
4516 same as @var{iw} / @var{ih}
4519 input sample aspect ratio
4522 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4525 horizontal and vertical chroma subsample values. For example for the
4526 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4529 @subsection Examples
4533 Add paddings with color "violet" to the input video. Output video
4534 size is 640x480, the top-left corner of the input video is placed at
4537 pad=640:480:0:40:violet
4540 The example above is equivalent to the following command:
4542 pad=width=640:height=480:x=0:y=40:color=violet
4546 Pad the input to get an output with dimensions increased by 3/2,
4547 and put the input video at the center of the padded area:
4549 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4553 Pad the input to get a squared output with size equal to the maximum
4554 value between the input width and height, and put the input video at
4555 the center of the padded area:
4557 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4561 Pad the input to get a final w/h ratio of 16:9:
4563 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4567 In case of anamorphic video, in order to set the output display aspect
4568 correctly, it is necessary to use @var{sar} in the expression,
4569 according to the relation:
4571 (ih * X / ih) * sar = output_dar
4572 X = output_dar / sar
4575 Thus the previous example needs to be modified to:
4577 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4581 Double output size and put the input video in the bottom-right
4582 corner of the output padded area:
4584 pad="2*iw:2*ih:ow-iw:oh-ih"
4588 @section pixdesctest
4590 Pixel format descriptor test filter, mainly useful for internal
4591 testing. The output video should be equal to the input video.
4595 format=monow, pixdesctest
4598 can be used to test the monowhite pixel format descriptor definition.
4602 Enable the specified chain of postprocessing subfilters using libpostproc. This
4603 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4604 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4605 Each subfilter and some options have a short and a long name that can be used
4606 interchangeably, i.e. dr/dering are the same.
4608 The filters accept the following options:
4612 Set postprocessing subfilters string.
4615 All subfilters share common options to determine their scope:
4619 Honor the quality commands for this subfilter.
4622 Do chrominance filtering, too (default).
4625 Do luminance filtering only (no chrominance).
4628 Do chrominance filtering only (no luminance).
4631 These options can be appended after the subfilter name, separated by a '|'.
4633 Available subfilters are:
4636 @item hb/hdeblock[|difference[|flatness]]
4637 Horizontal deblocking filter
4640 Difference factor where higher values mean more deblocking (default: @code{32}).
4642 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4645 @item vb/vdeblock[|difference[|flatness]]
4646 Vertical deblocking filter
4649 Difference factor where higher values mean more deblocking (default: @code{32}).
4651 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4654 @item ha/hadeblock[|difference[|flatness]]
4655 Accurate horizontal deblocking filter
4658 Difference factor where higher values mean more deblocking (default: @code{32}).
4660 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4663 @item va/vadeblock[|difference[|flatness]]
4664 Accurate vertical deblocking filter
4667 Difference factor where higher values mean more deblocking (default: @code{32}).
4669 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4673 The horizontal and vertical deblocking filters share the difference and
4674 flatness values so you cannot set different horizontal and vertical
4679 Experimental horizontal deblocking filter
4682 Experimental vertical deblocking filter
4687 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
4690 larger -> stronger filtering
4692 larger -> stronger filtering
4694 larger -> stronger filtering
4697 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4700 Stretch luminance to @code{0-255}.
4703 @item lb/linblenddeint
4704 Linear blend deinterlacing filter that deinterlaces the given block by
4705 filtering all lines with a @code{(1 2 1)} filter.
4707 @item li/linipoldeint
4708 Linear interpolating deinterlacing filter that deinterlaces the given block by
4709 linearly interpolating every second line.
4711 @item ci/cubicipoldeint
4712 Cubic interpolating deinterlacing filter deinterlaces the given block by
4713 cubically interpolating every second line.
4715 @item md/mediandeint
4716 Median deinterlacing filter that deinterlaces the given block by applying a
4717 median filter to every second line.
4719 @item fd/ffmpegdeint
4720 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4721 second line with a @code{(-1 4 2 4 -1)} filter.
4724 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4725 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4727 @item fq/forceQuant[|quantizer]
4728 Overrides the quantizer table from the input with the constant quantizer you
4736 Default pp filter combination (@code{hb|a,vb|a,dr|a})
4739 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
4742 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
4745 @subsection Examples
4749 Apply horizontal and vertical deblocking, deringing and automatic
4750 brightness/contrast:
4756 Apply default filters without brightness/contrast correction:
4762 Apply default filters and temporal denoiser:
4764 pp=default/tmpnoise|1|2|3
4768 Apply deblocking on luminance only, and switch vertical deblocking on or off
4769 automatically depending on available CPU time:
4777 Suppress a TV station logo, using an image file to determine which
4778 pixels comprise the logo. It works by filling in the pixels that
4779 comprise the logo with neighboring pixels.
4781 This filter requires one argument which specifies the filter bitmap
4782 file, which can be any image format supported by libavformat. The
4783 width and height of the image file must match those of the video
4784 stream being processed.
4786 Pixels in the provided bitmap image with a value of zero are not
4787 considered part of the logo, non-zero pixels are considered part of
4788 the logo. If you use white (255) for the logo and black (0) for the
4789 rest, you will be safe. For making the filter bitmap, it is
4790 recommended to take a screen capture of a black frame with the logo
4791 visible, and then using a threshold filter followed by the erode
4792 filter once or twice.
4794 If needed, little splotches can be fixed manually. Remember that if
4795 logo pixels are not covered, the filter quality will be much
4796 reduced. Marking too many pixels as part of the logo does not hurt as
4797 much, but it will increase the amount of blurring needed to cover over
4798 the image and will destroy more information than necessary, and extra
4799 pixels will slow things down on a large logo.
4803 Scale (resize) the input video, using the libswscale library.
4805 The scale filter forces the output display aspect ratio to be the same
4806 of the input, by changing the output sample aspect ratio.
4808 This filter accepts a list of named options in the form of
4809 @var{key}=@var{value} pairs separated by ":". If the key for the first
4810 two options is not specified, the assumed keys for the first two
4811 values are @code{w} and @code{h}. If the first option has no key and
4812 can be interpreted like a video size specification, it will be used
4813 to set the video size.
4815 A description of the accepted options follows.
4820 default value is @code{iw}. See below
4821 for the list of accepted constants.
4824 Output video height.
4825 default value is @code{ih}.
4826 See below for the list of accepted constants.
4829 Set the interlacing. It accepts the following values:
4833 force interlaced aware scaling
4836 do not apply interlaced scaling
4839 select interlaced aware scaling depending on whether the source frames
4840 are flagged as interlaced or not
4843 Default value is @code{0}.
4846 Set libswscale scaling flags. If not explictly specified the filter
4847 applies a bilinear scaling algorithm.
4850 Set the video size, the value must be a valid abbreviation or in the
4851 form @var{width}x@var{height}.
4854 The values of the @var{w} and @var{h} options are expressions
4855 containing the following constants:
4859 the input width and height
4862 same as @var{in_w} and @var{in_h}
4865 the output (cropped) width and height
4868 same as @var{out_w} and @var{out_h}
4871 same as @var{iw} / @var{ih}
4874 input sample aspect ratio
4877 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4880 horizontal and vertical chroma subsample values. For example for the
4881 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4884 If the input image format is different from the format requested by
4885 the next filter, the scale filter will convert the input to the
4888 If the value for @var{w} or @var{h} is 0, the respective input
4889 size is used for the output.
4891 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
4892 respective output size, a value that maintains the aspect ratio of the input
4895 @subsection Examples
4899 Scale the input video to a size of 200x100:
4904 This is equivalent to:
4915 Specify a size abbreviation for the output size:
4920 which can also be written as:
4926 Scale the input to 2x:
4932 The above is the same as:
4938 Scale the input to 2x with forced interlaced scaling:
4940 scale=2*iw:2*ih:interl=1
4944 Scale the input to half size:
4950 Increase the width, and set the height to the same size:
4956 Seek for Greek harmony:
4963 Increase the height, and set the width to 3/2 of the height:
4965 scale=w=3/2*oh:h=3/5*ih
4969 Increase the size, but make the size a multiple of the chroma
4972 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4976 Increase the width to a maximum of 500 pixels, keep the same input
4979 scale=w='min(500\, iw*3/2):h=-1'
4983 @section separatefields
4985 The @code{separatefields} takes a frame-based video input and splits
4986 each frame into its components fields, producing a new half height clip
4987 with twice the frame rate and twice the frame count.
4989 This filter use field-dominance information in frame to decide which
4990 of each pair of fields to place first in the output.
4991 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
4993 @section setdar, setsar
4995 The @code{setdar} filter sets the Display Aspect Ratio for the filter
4998 This is done by changing the specified Sample (aka Pixel) Aspect
4999 Ratio, according to the following equation:
5001 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
5004 Keep in mind that the @code{setdar} filter does not modify the pixel
5005 dimensions of the video frame. Also the display aspect ratio set by
5006 this filter may be changed by later filters in the filterchain,
5007 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
5010 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
5011 the filter output video.
5013 Note that as a consequence of the application of this filter, the
5014 output display aspect ratio will change according to the equation
5017 Keep in mind that the sample aspect ratio set by the @code{setsar}
5018 filter may be changed by later filters in the filterchain, e.g. if
5019 another "setsar" or a "setdar" filter is applied.
5021 The @code{setdar} and @code{setsar} filters accept a string in the
5022 form @var{num}:@var{den} expressing an aspect ratio, or the following
5023 named options, expressed as a sequence of @var{key}=@var{value} pairs,
5028 Set the maximum integer value to use for expressing numerator and
5029 denominator when reducing the expressed aspect ratio to a rational.
5030 Default value is @code{100}.
5032 @item r, ratio, dar, sar:
5033 Set the aspect ratio used by the filter.
5035 The parameter can be a floating point number string, an expression, or
5036 a string of the form @var{num}:@var{den}, where @var{num} and
5037 @var{den} are the numerator and denominator of the aspect ratio. If
5038 the parameter is not specified, it is assumed the value "0".
5039 In case the form "@var{num}:@var{den}" the @code{:} character should
5043 If the keys are omitted in the named options list, the specifed values
5044 are assumed to be @var{ratio} and @var{max} in that order.
5046 For example to change the display aspect ratio to 16:9, specify:
5049 # the above is equivalent to
5055 To change the sample aspect ratio to 10:11, specify:
5058 # the above is equivalent to
5062 To set a display aspect ratio of 16:9, and specify a maximum integer value of
5063 1000 in the aspect ratio reduction, use the command:
5065 setdar=ratio='16:9':max=1000
5071 Force field for the output video frame.
5073 The @code{setfield} filter marks the interlace type field for the
5074 output frames. It does not change the input frame, but only sets the
5075 corresponding property, which affects how the frame is treated by
5076 following filters (e.g. @code{fieldorder} or @code{yadif}).
5078 This filter accepts a single option @option{mode}, which can be
5079 specified either by setting @code{mode=VALUE} or setting the value
5080 alone. Available values are:
5084 Keep the same field property.
5087 Mark the frame as bottom-field-first.
5090 Mark the frame as top-field-first.
5093 Mark the frame as progressive.
5098 Show a line containing various information for each input video frame.
5099 The input video is not modified.
5101 The shown line contains a sequence of key/value pairs of the form
5102 @var{key}:@var{value}.
5104 A description of each shown parameter follows:
5108 sequential number of the input frame, starting from 0
5111 Presentation TimeStamp of the input frame, expressed as a number of
5112 time base units. The time base unit depends on the filter input pad.
5115 Presentation TimeStamp of the input frame, expressed as a number of
5119 position of the frame in the input stream, -1 if this information in
5120 unavailable and/or meaningless (for example in case of synthetic video)
5126 sample aspect ratio of the input frame, expressed in the form
5130 size of the input frame, expressed in the form
5131 @var{width}x@var{height}
5134 interlaced mode ("P" for "progressive", "T" for top field first, "B"
5135 for bottom field first)
5138 1 if the frame is a key frame, 0 otherwise
5141 picture type of the input frame ("I" for an I-frame, "P" for a
5142 P-frame, "B" for a B-frame, "?" for unknown type).
5143 Check also the documentation of the @code{AVPictureType} enum and of
5144 the @code{av_get_picture_type_char} function defined in
5145 @file{libavutil/avutil.h}.
5148 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
5150 @item plane_checksum
5151 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
5152 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
5157 Blur the input video without impacting the outlines.
5159 This filter accepts parameters as a list of @var{key}=@var{value} pairs,
5162 If the key of the first options is omitted, the arguments are
5163 interpreted according to the syntax:
5164 @var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
5166 A description of the accepted options follows.
5169 @item luma_radius, lr
5170 @item chroma_radius, cr
5171 Set the luma/chroma radius. The option value must be a float number in
5172 the range [0.1,5.0] that specifies the variance of the gaussian filter
5173 used to blur the image (slower if larger). Default value is 1.0.
5175 @item luma_strength, ls
5176 @item chroma_strength, cs
5177 Set the luma/chroma strength. The option value must be a float number
5178 in the range [-1.0,1.0] that configures the blurring. A value included
5179 in [0.0,1.0] will blur the image whereas a value included in
5180 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5182 @item luma_threshold, lt
5183 @item chroma_threshold, ct
5184 Set the luma/chroma threshold used as a coefficient to determine
5185 whether a pixel should be blurred or not. The option value must be an
5186 integer in the range [-30,30]. A value of 0 will filter all the image,
5187 a value included in [0,30] will filter flat areas and a value included
5188 in [-30,0] will filter edges. Default value is 0.
5191 If a chroma option is not explicitly set, the corresponding luma value
5196 Convert between different stereoscopic image formats.
5198 This filter accepts the following named options, expressed as a
5199 sequence of @var{key}=@var{value} pairs, separated by ":".
5203 Set stereoscopic image format of input.
5205 Available values for input image formats are:
5208 side by side parallel (left eye left, right eye right)
5211 side by side crosseye (right eye left, left eye right)
5214 side by side parallel with half width resolution
5215 (left eye left, right eye right)
5218 side by side crosseye with half width resolution
5219 (right eye left, left eye right)
5222 above-below (left eye above, right eye below)
5225 above-below (right eye above, left eye below)
5228 above-below with half height resolution
5229 (left eye above, right eye below)
5232 above-below with half height resolution
5233 (right eye above, left eye below)
5235 Default value is @samp{sbsl}.
5239 Set stereoscopic image format of output.
5241 Available values for output image formats are all the input formats as well as:
5244 anaglyph red/blue gray
5245 (red filter on left eye, blue filter on right eye)
5248 anaglyph red/green gray
5249 (red filter on left eye, green filter on right eye)
5252 anaglyph red/cyan gray
5253 (red filter on left eye, cyan filter on right eye)
5256 anaglyph red/cyan half colored
5257 (red filter on left eye, cyan filter on right eye)
5260 anaglyph red/cyan color
5261 (red filter on left eye, cyan filter on right eye)
5264 anaglyph red/cyan color optimized with the least squares projection of dubois
5265 (red filter on left eye, cyan filter on right eye)
5268 anaglyph green/magenta gray
5269 (green filter on left eye, magenta filter on right eye)
5272 anaglyph green/magenta half colored
5273 (green filter on left eye, magenta filter on right eye)
5276 anaglyph green/magenta colored
5277 (green filter on left eye, magenta filter on right eye)
5280 anaglyph green/magenta color optimized with the least squares projection of dubois
5281 (green filter on left eye, magenta filter on right eye)
5284 anaglyph yellow/blue gray
5285 (yellow filter on left eye, blue filter on right eye)
5288 anaglyph yellow/blue half colored
5289 (yellow filter on left eye, blue filter on right eye)
5292 anaglyph yellow/blue colored
5293 (yellow filter on left eye, blue filter on right eye)
5296 anaglyph yellow/blue color optimized with the least squares projection of dubois
5297 (yellow filter on left eye, blue filter on right eye)
5300 interleaved rows (left eye has top row, right eye starts on next row)
5303 interleaved rows (right eye has top row, left eye starts on next row)
5306 mono output (left eye only)
5309 mono output (right eye only)
5312 Default value is @samp{arcd}.
5318 Draw subtitles on top of input video using the libass library.
5320 To enable compilation of this filter you need to configure FFmpeg with
5321 @code{--enable-libass}. This filter also requires a build with libavcodec and
5322 libavformat to convert the passed subtitles file to ASS (Advanced Substation
5323 Alpha) subtitles format.
5325 The filter accepts the following options:
5329 Set the filename of the subtitle file to read. It must be specified.
5332 Specify the size of the original video, the video for which the ASS file
5333 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
5334 necessary to correctly scale the fonts if the aspect ratio has been changed.
5337 Set subtitles input character encoding. @code{subtitles} filter only. Only
5338 useful if not UTF-8.
5341 If the first key is not specified, it is assumed that the first value
5342 specifies the @option{filename}.
5344 For example, to render the file @file{sub.srt} on top of the input
5345 video, use the command:
5350 which is equivalent to:
5352 subtitles=filename=sub.srt
5357 Split input video into several identical outputs.
5359 The filter accepts a single parameter which specifies the number of outputs. If
5360 unspecified, it defaults to 2.
5364 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
5366 will create 5 copies of the input video.
5370 [in] split [splitout1][splitout2];
5371 [splitout1] crop=100:100:0:0 [cropout];
5372 [splitout2] pad=200:200:100:100 [padout];
5375 will create two separate outputs from the same input, one cropped and
5380 Scale the input by 2x and smooth using the Super2xSaI (Scale and
5381 Interpolate) pixel art scaling algorithm.
5383 Useful for enlarging pixel art images without reducing sharpness.
5389 Select the most representative frame in a given sequence of consecutive frames.
5391 The filter accepts the following options:
5395 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
5396 will pick one of them, and then handle the next batch of @var{n} frames until
5397 the end. Default is @code{100}.
5400 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
5401 value will result in a higher memory usage, so a high value is not recommended.
5403 @subsection Examples
5407 Extract one picture each 50 frames:
5413 Complete example of a thumbnail creation with @command{ffmpeg}:
5415 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
5421 Tile several successive frames together.
5423 It accepts a list of options in the form of @var{key}=@var{value} pairs
5424 separated by ":". A description of the accepted options follows.
5429 Set the grid size (i.e. the number of lines and columns) in the form
5433 Set the outer border margin in pixels.
5436 Set the inner border thickness (i.e. the number of pixels between frames). For
5437 more advanced padding options (such as having different values for the edges),
5438 refer to the pad video filter.
5441 Set the maximum number of frames to render in the given area. It must be less
5442 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
5443 the area will be used.
5447 Alternatively, the options can be specified as a flat string:
5449 @var{layout}[:@var{nb_frames}[:@var{margin}[:@var{padding}]]]
5451 For example, produce 8x8 PNG tiles of all keyframes (@option{-skip_frame
5454 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
5456 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
5457 duplicating each output frame to accomodate the originally detected frame
5460 Another example to display @code{5} pictures in an area of @code{3x2} frames,
5461 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
5462 mixed flat and named options:
5464 tile=3x2:nb_frames=5:padding=7:margin=2
5469 Perform various types of temporal field interlacing.
5471 Frames are counted starting from 1, so the first input frame is
5474 This filter accepts options in the form of @var{key}=@var{value} pairs
5476 Alternatively, the @var{mode} option can be specified as a value alone,
5477 optionally followed by a ":" and further ":" separated @var{key}=@var{value}
5480 A description of the accepted options follows.
5485 Specify the mode of the interlacing. This option can also be specified
5486 as a value alone. See below for a list of values for this option.
5488 Available values are:
5492 Move odd frames into the upper field, even into the lower field,
5493 generating a double height frame at half frame rate.
5496 Only output even frames, odd frames are dropped, generating a frame with
5497 unchanged height at half frame rate.
5500 Only output odd frames, even frames are dropped, generating a frame with
5501 unchanged height at half frame rate.
5504 Expand each frame to full height, but pad alternate lines with black,
5505 generating a frame with double height at the same input frame rate.
5507 @item interleave_top, 4
5508 Interleave the upper field from odd frames with the lower field from
5509 even frames, generating a frame with unchanged height at half frame rate.
5511 @item interleave_bottom, 5
5512 Interleave the lower field from odd frames with the upper field from
5513 even frames, generating a frame with unchanged height at half frame rate.
5515 @item interlacex2, 6
5516 Double frame rate with unchanged height. Frames are inserted each
5517 containing the second temporal field from the previous input frame and
5518 the first temporal field from the next input frame. This mode relies on
5519 the top_field_first flag. Useful for interlaced video displays with no
5520 field synchronisation.
5523 Numeric values are deprecated but are accepted for backward
5524 compatibility reasons.
5526 Default mode is @code{merge}.
5529 Specify flags influencing the filter process.
5531 Available value for @var{flags} is:
5534 @item low_pass_filter, vlfp
5535 Enable vertical low-pass filtering in the filter.
5536 Vertical low-pass filtering is required when creating an interlaced
5537 destination from a progressive source which contains high-frequency
5538 vertical detail. Filtering will reduce interlace 'twitter' and Moire
5541 Vertical low-pass filtering can only be enabled for @option{mode}
5542 @var{interleave_top} and @var{interleave_bottom}.
5549 Transpose rows with columns in the input video and optionally flip it.
5551 The filter accepts parameters as a list of @var{key}=@var{value}
5552 pairs, separated by ':'. If the key of the first options is omitted,
5553 the arguments are interpreted according to the syntax
5554 @var{dir}:@var{passthrough}.
5558 Specify the transposition direction. Can assume the following values:
5562 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
5570 Rotate by 90 degrees clockwise, that is:
5578 Rotate by 90 degrees counterclockwise, that is:
5586 Rotate by 90 degrees clockwise and vertically flip, that is:
5594 For values between 4-7, the transposition is only done if the input
5595 video geometry is portrait and not landscape. These values are
5596 deprecated, the @code{passthrough} option should be used instead.
5599 Do not apply the transposition if the input geometry matches the one
5600 specified by the specified value. It accepts the following values:
5603 Always apply transposition.
5605 Preserve portrait geometry (when @var{height} >= @var{width}).
5607 Preserve landscape geometry (when @var{width} >= @var{height}).
5610 Default value is @code{none}.
5613 For example to rotate by 90 degrees clockwise and preserve portrait
5616 transpose=dir=1:passthrough=portrait
5619 The command above can also be specified as:
5621 transpose=1:portrait
5626 Sharpen or blur the input video.
5628 This filter accepts parameters as a list of @var{key}=@var{value} pairs,
5631 If the key of the first options is omitted, the arguments are
5632 interpreted according to the syntax:
5633 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
5635 A description of the accepted options follows.
5638 @item luma_msize_x, lx
5639 @item chroma_msize_x, cx
5640 Set the luma/chroma matrix horizontal size. It must be an odd integer
5641 between 3 and 63, default value is 5.
5643 @item luma_msize_y, ly
5644 @item chroma_msize_y, cy
5645 Set the luma/chroma matrix vertical size. It must be an odd integer
5646 between 3 and 63, default value is 5.
5648 @item luma_amount, la
5649 @item chroma_amount, ca
5650 Set the luma/chroma effect strength. It can be a float number,
5651 reasonable values lay between -1.5 and 1.5.
5653 Negative values will blur the input video, while positive values will
5654 sharpen it, a value of zero will disable the effect.
5656 Default value is 1.0 for @option{luma_amount}, 0.0 for
5657 @option{chroma_amount}.
5660 @subsection Examples
5664 Apply strong luma sharpen effect:
5670 Apply strong blur of both luma and chroma parameters:
5672 unsharp=7:7:-2:7:7:-2
5678 Flip the input video vertically.
5681 ffmpeg -i in.avi -vf "vflip" out.avi
5686 Deinterlace the input video ("yadif" means "yet another deinterlacing
5689 The filter accepts parameters as a list of @var{key}=@var{value}
5690 pairs, separated by ":". If the key of the first options is omitted,
5691 the arguments are interpreted according to syntax
5692 @var{mode}:@var{parity}:@var{deint}.
5694 The description of the accepted parameters follows.
5698 Specify the interlacing mode to adopt. Accept one of the following
5703 output 1 frame for each frame
5705 output 1 frame for each field
5706 @item 2, send_frame_nospatial
5707 like @code{send_frame} but skip spatial interlacing check
5708 @item 3, send_field_nospatial
5709 like @code{send_field} but skip spatial interlacing check
5712 Default value is @code{send_frame}.
5715 Specify the picture field parity assumed for the input interlaced
5716 video. Accept one of the following values:
5720 assume top field first
5722 assume bottom field first
5724 enable automatic detection
5727 Default value is @code{auto}.
5728 If interlacing is unknown or decoder does not export this information,
5729 top field first will be assumed.
5732 Specify which frames to deinterlace. Accept one of the following
5737 deinterlace all frames
5739 only deinterlace frames marked as interlaced
5742 Default value is @code{all}.
5745 @c man end VIDEO FILTERS
5747 @chapter Video Sources
5748 @c man begin VIDEO SOURCES
5750 Below is a description of the currently available video sources.
5754 Buffer video frames, and make them available to the filter chain.
5756 This source is mainly intended for a programmatic use, in particular
5757 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5759 It accepts a list of options in the form of @var{key}=@var{value} pairs
5760 separated by ":". A description of the accepted options follows.
5765 Specify the size (width and height) of the buffered video frames.
5768 A string representing the pixel format of the buffered video frames.
5769 It may be a number corresponding to a pixel format, or a pixel format
5773 Specify the timebase assumed by the timestamps of the buffered frames.
5776 Specify the frame rate expected for the video stream.
5779 Specify the sample aspect ratio assumed by the video frames.
5782 Specify the optional parameters to be used for the scale filter which
5783 is automatically inserted when an input change is detected in the
5784 input size or format.
5789 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
5792 will instruct the source to accept video frames with size 320x240 and
5793 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5794 square pixels (1:1 sample aspect ratio).
5795 Since the pixel format with name "yuv410p" corresponds to the number 6
5796 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5797 this example corresponds to:
5799 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5802 Alternatively, the options can be specified as a flat string, but this
5803 syntax is deprecated:
5805 @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}]
5809 Create a pattern generated by an elementary cellular automaton.
5811 The initial state of the cellular automaton can be defined through the
5812 @option{filename}, and @option{pattern} options. If such options are
5813 not specified an initial state is created randomly.
5815 At each new frame a new row in the video is filled with the result of
5816 the cellular automaton next generation. The behavior when the whole
5817 frame is filled is defined by the @option{scroll} option.
5819 This source accepts a list of options in the form of
5820 @var{key}=@var{value} pairs separated by ":". A description of the
5821 accepted options follows.
5825 Read the initial cellular automaton state, i.e. the starting row, from
5827 In the file, each non-whitespace character is considered an alive
5828 cell, a newline will terminate the row, and further characters in the
5829 file will be ignored.
5832 Read the initial cellular automaton state, i.e. the starting row, from
5833 the specified string.
5835 Each non-whitespace character in the string is considered an alive
5836 cell, a newline will terminate the row, and further characters in the
5837 string will be ignored.
5840 Set the video rate, that is the number of frames generated per second.
5843 @item random_fill_ratio, ratio
5844 Set the random fill ratio for the initial cellular automaton row. It
5845 is a floating point number value ranging from 0 to 1, defaults to
5848 This option is ignored when a file or a pattern is specified.
5850 @item random_seed, seed
5851 Set the seed for filling randomly the initial row, must be an integer
5852 included between 0 and UINT32_MAX. If not specified, or if explicitly
5853 set to -1, the filter will try to use a good random seed on a best
5857 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5858 Default value is 110.
5861 Set the size of the output video.
5863 If @option{filename} or @option{pattern} is specified, the size is set
5864 by default to the width of the specified initial state row, and the
5865 height is set to @var{width} * PHI.
5867 If @option{size} is set, it must contain the width of the specified
5868 pattern string, and the specified pattern will be centered in the
5871 If a filename or a pattern string is not specified, the size value
5872 defaults to "320x518" (used for a randomly generated initial state).
5875 If set to 1, scroll the output upward when all the rows in the output
5876 have been already filled. If set to 0, the new generated row will be
5877 written over the top row just after the bottom row is filled.
5880 @item start_full, full
5881 If set to 1, completely fill the output with generated rows before
5882 outputting the first frame.
5883 This is the default behavior, for disabling set the value to 0.
5886 If set to 1, stitch the left and right row edges together.
5887 This is the default behavior, for disabling set the value to 0.
5890 @subsection Examples
5894 Read the initial state from @file{pattern}, and specify an output of
5897 cellauto=f=pattern:s=200x400
5901 Generate a random initial row with a width of 200 cells, with a fill
5904 cellauto=ratio=2/3:s=200x200
5908 Create a pattern generated by rule 18 starting by a single alive cell
5909 centered on an initial row with width 100:
5911 cellauto=p=@@:s=100x400:full=0:rule=18
5915 Specify a more elaborated initial pattern:
5917 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5924 Generate a Mandelbrot set fractal, and progressively zoom towards the
5925 point specified with @var{start_x} and @var{start_y}.
5927 This source accepts a list of options in the form of
5928 @var{key}=@var{value} pairs separated by ":". A description of the
5929 accepted options follows.
5934 Set the terminal pts value. Default value is 400.
5937 Set the terminal scale value.
5938 Must be a floating point value. Default value is 0.3.
5941 Set the inner coloring mode, that is the algorithm used to draw the
5942 Mandelbrot fractal internal region.
5944 It shall assume one of the following values:
5949 Show time until convergence.
5951 Set color based on point closest to the origin of the iterations.
5956 Default value is @var{mincol}.
5959 Set the bailout value. Default value is 10.0.
5962 Set the maximum of iterations performed by the rendering
5963 algorithm. Default value is 7189.
5966 Set outer coloring mode.
5967 It shall assume one of following values:
5969 @item iteration_count
5970 Set iteration cound mode.
5971 @item normalized_iteration_count
5972 set normalized iteration count mode.
5974 Default value is @var{normalized_iteration_count}.
5977 Set frame rate, expressed as number of frames per second. Default
5981 Set frame size. Default value is "640x480".
5984 Set the initial scale value. Default value is 3.0.
5987 Set the initial x position. Must be a floating point value between
5988 -100 and 100. Default value is -0.743643887037158704752191506114774.
5991 Set the initial y position. Must be a floating point value between
5992 -100 and 100. Default value is -0.131825904205311970493132056385139.
5997 Generate various test patterns, as generated by the MPlayer test filter.
5999 The size of the generated video is fixed, and is 256x256.
6000 This source is useful in particular for testing encoding features.
6002 This source accepts an optional sequence of @var{key}=@var{value} pairs,
6003 separated by ":". The description of the accepted options follows.
6008 Specify the frame rate of the sourced video, as the number of frames
6009 generated per second. It has to be a string in the format
6010 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6011 number or a valid video frame rate abbreviation. The default value is
6015 Set the video duration of the sourced video. The accepted syntax is:
6020 See also the function @code{av_parse_time()}.
6022 If not specified, or the expressed duration is negative, the video is
6023 supposed to be generated forever.
6027 Set the number or the name of the test to perform. Supported tests are:
6042 Default value is "all", which will cycle through the list of all tests.
6045 For example the following:
6050 will generate a "dc_luma" test pattern.
6054 Provide a frei0r source.
6056 To enable compilation of this filter you need to install the frei0r
6057 header and configure FFmpeg with @code{--enable-frei0r}.
6059 This source accepts the following options:
6064 The size of the video to generate, may be a string of the form
6065 @var{width}x@var{height} or a frame size abbreviation.
6068 Framerate of the generated video, may be a string of the form
6069 @var{num}/@var{den} or a frame rate abbreviation.
6072 The name to the frei0r source to load. For more information regarding frei0r and
6073 how to set the parameters read the section @ref{frei0r} in the description of
6077 A '|'-separated list of parameters to pass to the frei0r source.
6081 For example, to generate a frei0r partik0l source with size 200x200
6082 and frame rate 10 which is overlayed on the overlay filter main input:
6084 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
6089 Generate a life pattern.
6091 This source is based on a generalization of John Conway's life game.
6093 The sourced input represents a life grid, each pixel represents a cell
6094 which can be in one of two possible states, alive or dead. Every cell
6095 interacts with its eight neighbours, which are the cells that are
6096 horizontally, vertically, or diagonally adjacent.
6098 At each interaction the grid evolves according to the adopted rule,
6099 which specifies the number of neighbor alive cells which will make a
6100 cell stay alive or born. The @option{rule} option allows to specify
6103 This source accepts a list of options in the form of
6104 @var{key}=@var{value} pairs separated by ":". A description of the
6105 accepted options follows.
6109 Set the file from which to read the initial grid state. In the file,
6110 each non-whitespace character is considered an alive cell, and newline
6111 is used to delimit the end of each row.
6113 If this option is not specified, the initial grid is generated
6117 Set the video rate, that is the number of frames generated per second.
6120 @item random_fill_ratio, ratio
6121 Set the random fill ratio for the initial random grid. It is a
6122 floating point number value ranging from 0 to 1, defaults to 1/PHI.
6123 It is ignored when a file is specified.
6125 @item random_seed, seed
6126 Set the seed for filling the initial random grid, must be an integer
6127 included between 0 and UINT32_MAX. If not specified, or if explicitly
6128 set to -1, the filter will try to use a good random seed on a best
6134 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
6135 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
6136 @var{NS} specifies the number of alive neighbor cells which make a
6137 live cell stay alive, and @var{NB} the number of alive neighbor cells
6138 which make a dead cell to become alive (i.e. to "born").
6139 "s" and "b" can be used in place of "S" and "B", respectively.
6141 Alternatively a rule can be specified by an 18-bits integer. The 9
6142 high order bits are used to encode the next cell state if it is alive
6143 for each number of neighbor alive cells, the low order bits specify
6144 the rule for "borning" new cells. Higher order bits encode for an
6145 higher number of neighbor cells.
6146 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
6147 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
6149 Default value is "S23/B3", which is the original Conway's game of life
6150 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
6151 cells, and will born a new cell if there are three alive cells around
6155 Set the size of the output video.
6157 If @option{filename} is specified, the size is set by default to the
6158 same size of the input file. If @option{size} is set, it must contain
6159 the size specified in the input file, and the initial grid defined in
6160 that file is centered in the larger resulting area.
6162 If a filename is not specified, the size value defaults to "320x240"
6163 (used for a randomly generated initial grid).
6166 If set to 1, stitch the left and right grid edges together, and the
6167 top and bottom edges also. Defaults to 1.
6170 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
6171 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
6172 value from 0 to 255.
6175 Set the color of living (or new born) cells.
6178 Set the color of dead cells. If @option{mold} is set, this is the first color
6179 used to represent a dead cell.
6182 Set mold color, for definitely dead and moldy cells.
6185 @subsection Examples
6189 Read a grid from @file{pattern}, and center it on a grid of size
6192 life=f=pattern:s=300x300
6196 Generate a random grid of size 200x200, with a fill ratio of 2/3:
6198 life=ratio=2/3:s=200x200
6202 Specify a custom rule for evolving a randomly generated grid:
6208 Full example with slow death effect (mold) using @command{ffplay}:
6210 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
6214 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
6216 The @code{color} source provides an uniformly colored input.
6218 The @code{nullsrc} source returns unprocessed video frames. It is
6219 mainly useful to be employed in analysis / debugging tools, or as the
6220 source for filters which ignore the input data.
6222 The @code{rgbtestsrc} source generates an RGB test pattern useful for
6223 detecting RGB vs BGR issues. You should see a red, green and blue
6224 stripe from top to bottom.
6226 The @code{smptebars} source generates a color bars pattern, based on
6227 the SMPTE Engineering Guideline EG 1-1990.
6229 The @code{testsrc} source generates a test video pattern, showing a
6230 color pattern, a scrolling gradient and a timestamp. This is mainly
6231 intended for testing purposes.
6233 These sources accept an optional sequence of @var{key}=@var{value} pairs,
6234 separated by ":". The description of the accepted options follows.
6239 Specify the color of the source, only used in the @code{color}
6240 source. It can be the name of a color (case insensitive match) or a
6241 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
6242 default value is "black".
6245 Specify the size of the sourced video, it may be a string of the form
6246 @var{width}x@var{height}, or the name of a size abbreviation. The
6247 default value is "320x240".
6250 Specify the frame rate of the sourced video, as the number of frames
6251 generated per second. It has to be a string in the format
6252 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6253 number or a valid video frame rate abbreviation. The default value is
6257 Set the sample aspect ratio of the sourced video.
6260 Set the video duration of the sourced video. The accepted syntax is:
6262 [-]HH[:MM[:SS[.m...]]]
6265 See also the function @code{av_parse_time()}.
6267 If not specified, or the expressed duration is negative, the video is
6268 supposed to be generated forever.
6271 Set the number of decimals to show in the timestamp, only used in the
6272 @code{testsrc} source.
6274 The displayed timestamp value will correspond to the original
6275 timestamp value multiplied by the power of 10 of the specified
6276 value. Default value is 0.
6279 For example the following:
6281 testsrc=duration=5.3:size=qcif:rate=10
6284 will generate a video with a duration of 5.3 seconds, with size
6285 176x144 and a frame rate of 10 frames per second.
6287 The following graph description will generate a red source
6288 with an opacity of 0.2, with size "qcif" and a frame rate of 10
6291 color=c=red@@0.2:s=qcif:r=10
6294 If the input content is to be ignored, @code{nullsrc} can be used. The
6295 following command generates noise in the luminance plane by employing
6296 the @code{geq} filter:
6298 nullsrc=s=256x256, geq=random(1)*255:128:128
6301 @c man end VIDEO SOURCES
6303 @chapter Video Sinks
6304 @c man begin VIDEO SINKS
6306 Below is a description of the currently available video sinks.
6310 Buffer video frames, and make them available to the end of the filter
6313 This sink is mainly intended for a programmatic use, in particular
6314 through the interface defined in @file{libavfilter/buffersink.h}.
6316 It does not require a string parameter in input, but you need to
6317 specify a pointer to a list of supported pixel formats terminated by
6318 -1 in the opaque parameter provided to @code{avfilter_init_filter}
6319 when initializing this sink.
6323 Null video sink, do absolutely nothing with the input video. It is
6324 mainly useful as a template and to be employed in analysis / debugging
6327 @c man end VIDEO SINKS
6329 @chapter Multimedia Filters
6330 @c man begin MULTIMEDIA FILTERS
6332 Below is a description of the currently available multimedia filters.
6334 @section aperms, perms
6336 Set read/write permissions for the output frames.
6338 These filters are mainly aimed at developers to test direct path in the
6339 following filter in the filtergraph.
6341 The filters accept the following options:
6345 Select the permissions mode.
6347 It accepts the following values:
6350 Do nothing. This is the default.
6352 Set all the output frames read-only.
6354 Set all the output frames directly writable.
6356 Make the frame read-only if writable, and writable if read-only.
6358 Set each output frame read-only or writable randomly.
6362 Set the seed for the @var{random} mode, must be an integer included between
6363 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
6364 @code{-1}, the filter will try to use a good random seed on a best effort
6368 Note: in case of auto-inserted filter between the permission filter and the
6369 following one, the permission might not be received as expected in that
6370 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
6371 perms/aperms filter can avoid this problem.
6374 Add a phasing effect to the input audio.
6376 A phaser filter creates series of peaks and troughs in the frequency spectrum.
6377 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
6379 The filter accepts parameters as a list of @var{key}=@var{value}
6380 pairs, separated by ":".
6382 A description of the accepted parameters follows.
6386 Set input gain. Default is 0.4.
6389 Set output gain. Default is 0.74
6392 Set delay in milliseconds. Default is 3.0.
6395 Set decay. Default is 0.4.
6398 Set modulation speed in Hz. Default is 0.5.
6401 Set modulation type. Default is triangular.
6403 It accepts the following values:
6410 @section aselect, select
6411 Select frames to pass in output.
6413 These filters accept a single option @option{expr} or @option{e}
6414 specifying the select expression, which can be specified either by
6415 specyfing @code{expr=VALUE} or specifying the expression
6418 The select expression is evaluated for each input frame. If the
6419 evaluation result is a non-zero value, the frame is selected and
6420 passed to the output, otherwise it is discarded.
6422 The expression can contain the following constants:
6426 the sequential number of the filtered frame, starting from 0
6429 the sequential number of the selected frame, starting from 0
6431 @item prev_selected_n
6432 the sequential number of the last selected frame, NAN if undefined
6435 timebase of the input timestamps
6438 the PTS (Presentation TimeStamp) of the filtered video frame,
6439 expressed in @var{TB} units, NAN if undefined
6442 the PTS (Presentation TimeStamp) of the filtered video frame,
6443 expressed in seconds, NAN if undefined
6446 the PTS of the previously filtered video frame, NAN if undefined
6448 @item prev_selected_pts
6449 the PTS of the last previously filtered video frame, NAN if undefined
6451 @item prev_selected_t
6452 the PTS of the last previously selected video frame, NAN if undefined
6455 the PTS of the first video frame in the video, NAN if undefined
6458 the time of the first video frame in the video, NAN if undefined
6460 @item pict_type @emph{(video only)}
6461 the type of the filtered frame, can assume one of the following
6473 @item interlace_type @emph{(video only)}
6474 the frame interlace type, can assume one of the following values:
6477 the frame is progressive (not interlaced)
6479 the frame is top-field-first
6481 the frame is bottom-field-first
6484 @item consumed_sample_n @emph{(audio only)}
6485 the number of selected samples before the current frame
6487 @item samples_n @emph{(audio only)}
6488 the number of samples in the current frame
6490 @item sample_rate @emph{(audio only)}
6491 the input sample rate
6494 1 if the filtered frame is a key-frame, 0 otherwise
6497 the position in the file of the filtered frame, -1 if the information
6498 is not available (e.g. for synthetic video)
6500 @item scene @emph{(video only)}
6501 value between 0 and 1 to indicate a new scene; a low value reflects a low
6502 probability for the current frame to introduce a new scene, while a higher
6503 value means the current frame is more likely to be one (see the example below)
6507 The default value of the select expression is "1".
6509 @subsection Examples
6513 Select all frames in input:
6518 The example above is the same as:
6530 Select only I-frames:
6532 select='eq(pict_type\,I)'
6536 Select one frame every 100:
6538 select='not(mod(n\,100))'
6542 Select only frames contained in the 10-20 time interval:
6544 select='gte(t\,10)*lte(t\,20)'
6548 Select only I frames contained in the 10-20 time interval:
6550 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
6554 Select frames with a minimum distance of 10 seconds:
6556 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
6560 Use aselect to select only audio frames with samples number > 100:
6562 aselect='gt(samples_n\,100)'
6566 Create a mosaic of the first scenes:
6568 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
6571 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
6575 @section asendcmd, sendcmd
6577 Send commands to filters in the filtergraph.
6579 These filters read commands to be sent to other filters in the
6582 @code{asendcmd} must be inserted between two audio filters,
6583 @code{sendcmd} must be inserted between two video filters, but apart
6584 from that they act the same way.
6586 The specification of commands can be provided in the filter arguments
6587 with the @var{commands} option, or in a file specified by the
6588 @var{filename} option.
6590 These filters accept the following options:
6593 Set the commands to be read and sent to the other filters.
6595 Set the filename of the commands to be read and sent to the other
6599 @subsection Commands syntax
6601 A commands description consists of a sequence of interval
6602 specifications, comprising a list of commands to be executed when a
6603 particular event related to that interval occurs. The occurring event
6604 is typically the current frame time entering or leaving a given time
6607 An interval is specified by the following syntax:
6609 @var{START}[-@var{END}] @var{COMMANDS};
6612 The time interval is specified by the @var{START} and @var{END} times.
6613 @var{END} is optional and defaults to the maximum time.
6615 The current frame time is considered within the specified interval if
6616 it is included in the interval [@var{START}, @var{END}), that is when
6617 the time is greater or equal to @var{START} and is lesser than
6620 @var{COMMANDS} consists of a sequence of one or more command
6621 specifications, separated by ",", relating to that interval. The
6622 syntax of a command specification is given by:
6624 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
6627 @var{FLAGS} is optional and specifies the type of events relating to
6628 the time interval which enable sending the specified command, and must
6629 be a non-null sequence of identifier flags separated by "+" or "|" and
6630 enclosed between "[" and "]".
6632 The following flags are recognized:
6635 The command is sent when the current frame timestamp enters the
6636 specified interval. In other words, the command is sent when the
6637 previous frame timestamp was not in the given interval, and the
6641 The command is sent when the current frame timestamp leaves the
6642 specified interval. In other words, the command is sent when the
6643 previous frame timestamp was in the given interval, and the
6647 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
6650 @var{TARGET} specifies the target of the command, usually the name of
6651 the filter class or a specific filter instance name.
6653 @var{COMMAND} specifies the name of the command for the target filter.
6655 @var{ARG} is optional and specifies the optional list of argument for
6656 the given @var{COMMAND}.
6658 Between one interval specification and another, whitespaces, or
6659 sequences of characters starting with @code{#} until the end of line,
6660 are ignored and can be used to annotate comments.
6662 A simplified BNF description of the commands specification syntax
6665 @var{COMMAND_FLAG} ::= "enter" | "leave"
6666 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
6667 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
6668 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
6669 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
6670 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
6673 @subsection Examples
6677 Specify audio tempo change at second 4:
6679 asendcmd=c='4.0 atempo tempo 1.5',atempo
6683 Specify a list of drawtext and hue commands in a file.
6685 # show text in the interval 5-10
6686 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
6687 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
6689 # desaturate the image in the interval 15-20
6690 15.0-20.0 [enter] hue reinit s=0,
6691 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
6692 [leave] hue reinit s=1,
6693 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
6695 # apply an exponential saturation fade-out effect, starting from time 25
6696 25 [enter] hue s=exp(t-25)
6699 A filtergraph allowing to read and process the above command list
6700 stored in a file @file{test.cmd}, can be specified with:
6702 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
6707 @section asetpts, setpts
6709 Change the PTS (presentation timestamp) of the input frames.
6711 @code{asetpts} works on audio frames, @code{setpts} on video frames.
6713 Accept in input an expression evaluated through the eval API, which
6714 can contain the following constants:
6718 frame rate, only defined for constant frame-rate video
6721 the presentation timestamp in input
6724 the count of the input frame, starting from 0.
6726 @item NB_CONSUMED_SAMPLES
6727 the number of consumed samples, not including the current frame (only
6731 the number of samples in the current frame (only audio)
6737 the PTS of the first frame
6740 the time in seconds of the first frame
6743 tell if the current frame is interlaced
6746 the time in seconds of the current frame
6752 original position in the file of the frame, or undefined if undefined
6753 for the current frame
6759 previous input time in seconds
6765 previous output time in seconds
6768 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
6772 wallclock (RTC) time at the start of the movie in microseconds
6775 @subsection Examples
6779 Start counting PTS from zero
6785 Apply fast motion effect:
6791 Apply slow motion effect:
6797 Set fixed rate of 25 frames per second:
6803 Set fixed rate 25 fps with some jitter:
6805 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6809 Apply an offset of 10 seconds to the input PTS:
6815 Generate timestamps from a "live source" and rebase onto the current timebase:
6817 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6823 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6824 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6825 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6826 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6828 The filter also has a video output (see the @var{video} option) with a real
6829 time graph to observe the loudness evolution. The graphic contains the logged
6830 message mentioned above, so it is not printed anymore when this option is set,
6831 unless the verbose logging is set. The main graphing area contains the
6832 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6833 the momentary loudness (400 milliseconds).
6835 More information about the Loudness Recommendation EBU R128 on
6836 @url{http://tech.ebu.ch/loudness}.
6838 The filter accepts the following options:
6843 Activate the video output. The audio stream is passed unchanged whether this
6844 option is set or no. The video stream will be the first output stream if
6845 activated. Default is @code{0}.
6848 Set the video size. This option is for video only. Default and minimum
6849 resolution is @code{640x480}.
6852 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6853 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6854 other integer value between this range is allowed.
6857 Set metadata injection. If set to @code{1}, the audio input will be segmented
6858 into 100ms output frames, each of them containing various loudness information
6859 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
6861 Default is @code{0}.
6864 Force the frame logging level.
6866 Available values are:
6869 information logging level
6871 verbose logging level
6874 By default, the logging level is set to @var{info}. If the @option{video} or
6875 the @option{metadata} options are set, it switches to @var{verbose}.
6878 @subsection Examples
6882 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
6884 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6888 Run an analysis with @command{ffmpeg}:
6890 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6894 @section settb, asettb
6896 Set the timebase to use for the output frames timestamps.
6897 It is mainly useful for testing timebase configuration.
6899 This filter accepts a single option @option{tb}, which can be
6900 specified either by setting @option{tb}=@var{VALUE} or setting the
6903 The value for @option{tb} is an arithmetic expression representing a
6904 rational. The expression can contain the constants "AVTB" (the default
6905 timebase), "intb" (the input timebase) and "sr" (the sample rate,
6906 audio only). Default value is "intb".
6908 @subsection Examples
6912 Set the timebase to 1/25:
6918 Set the timebase to 1/10:
6924 Set the timebase to 1001/1000:
6930 Set the timebase to 2*intb:
6936 Set the default timebase value:
6944 Concatenate audio and video streams, joining them together one after the
6947 The filter works on segments of synchronized video and audio streams. All
6948 segments must have the same number of streams of each type, and that will
6949 also be the number of streams at output.
6951 The filter accepts the following named parameters:
6955 Set the number of segments. Default is 2.
6958 Set the number of output video streams, that is also the number of video
6959 streams in each segment. Default is 1.
6962 Set the number of output audio streams, that is also the number of video
6963 streams in each segment. Default is 0.
6966 Activate unsafe mode: do not fail if segments have a different format.
6970 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
6971 @var{a} audio outputs.
6973 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
6974 segment, in the same order as the outputs, then the inputs for the second
6977 Related streams do not always have exactly the same duration, for various
6978 reasons including codec frame size or sloppy authoring. For that reason,
6979 related synchronized streams (e.g. a video and its audio track) should be
6980 concatenated at once. The concat filter will use the duration of the longest
6981 stream in each segment (except the last one), and if necessary pad shorter
6982 audio streams with silence.
6984 For this filter to work correctly, all segments must start at timestamp 0.
6986 All corresponding streams must have the same parameters in all segments; the
6987 filtering system will automatically select a common pixel format for video
6988 streams, and a common sample format, sample rate and channel layout for
6989 audio streams, but other settings, such as resolution, must be converted
6990 explicitly by the user.
6992 Different frame rates are acceptable but will result in variable frame rate
6993 at output; be sure to configure the output file to handle it.
6995 @subsection Examples
6999 Concatenate an opening, an episode and an ending, all in bilingual version
7000 (video in stream 0, audio in streams 1 and 2):
7002 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
7003 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
7004 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
7005 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
7009 Concatenate two parts, handling audio and video separately, using the
7010 (a)movie sources, and adjusting the resolution:
7012 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
7013 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
7014 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
7016 Note that a desync will happen at the stitch if the audio and video streams
7017 do not have exactly the same duration in the first file.
7021 @section showspectrum
7023 Convert input audio to a video output, representing the audio frequency
7026 The filter accepts the following options:
7030 Specify the video size for the output. Default value is @code{640x512}.
7033 Specify if the spectrum should slide along the window. Default value is
7037 Specify display mode.
7039 It accepts the following values:
7042 all channels are displayed in the same row
7044 all channels are displayed in separate rows
7047 Default value is @samp{combined}.
7050 Specify display color mode.
7052 It accepts the following values:
7055 each channel is displayed in a separate color
7057 each channel is is displayed using the same color scheme
7060 Default value is @samp{channel}.
7063 Specify scale used for calculating intensity color values.
7065 It accepts the following values:
7070 square root, default
7077 Default value is @samp{sqrt}.
7080 Set saturation modifier for displayed colors. Negative values provide
7081 alternative color scheme. @code{0} is no saturation at all.
7082 Saturation must be in [-10.0, 10.0] range.
7083 Default value is @code{1}.
7086 The usage is very similar to the showwaves filter; see the examples in that
7089 @subsection Examples
7093 Large window with logarithmic color scaling:
7095 showspectrum=s=1280x480:scale=log
7099 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
7101 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
7102 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
7108 Convert input audio to a video output, representing the samples waves.
7110 The filter accepts the following named parameters:
7115 Available values are:
7118 Draw a point for each sample.
7121 Draw a vertical line for each sample.
7124 Default value is @code{point}.
7127 Set the number of samples which are printed on the same column. A
7128 larger value will decrease the frame rate. Must be a positive
7129 integer. This option can be set only if the value for @var{rate}
7130 is not explicitly specified.
7133 Set the (approximate) output frame rate. This is done by setting the
7134 option @var{n}. Default value is "25".
7137 Specify the video size for the output. Default value is "600x240".
7140 @subsection Examples
7144 Output the input file audio and the corresponding video representation
7147 amovie=a.mp3,asplit[out0],showwaves[out1]
7151 Create a synthetic signal and show it with showwaves, forcing a
7152 frame rate of 30 frames per second:
7154 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
7158 @c man end MULTIMEDIA FILTERS
7160 @chapter Multimedia Sources
7161 @c man begin MULTIMEDIA SOURCES
7163 Below is a description of the currently available multimedia sources.
7167 This is the same as @ref{movie} source, except it selects an audio
7173 Read audio and/or video stream(s) from a movie container.
7175 It accepts the syntax: @var{movie_name}[:@var{options}] where
7176 @var{movie_name} is the name of the resource to read (not necessarily
7177 a file but also a device or a stream accessed through some protocol),
7178 and @var{options} is an optional sequence of @var{key}=@var{value}
7179 pairs, separated by ":".
7181 The description of the accepted options follows.
7185 @item format_name, f
7186 Specifies the format assumed for the movie to read, and can be either
7187 the name of a container or an input device. If not specified the
7188 format is guessed from @var{movie_name} or by probing.
7190 @item seek_point, sp
7191 Specifies the seek point in seconds, the frames will be output
7192 starting from this seek point, the parameter is evaluated with
7193 @code{av_strtod} so the numerical value may be suffixed by an IS
7194 postfix. Default value is "0".
7197 Specifies the streams to read. Several streams can be specified,
7198 separated by "+". The source will then have as many outputs, in the
7199 same order. The syntax is explained in the ``Stream specifiers''
7200 section in the ffmpeg manual. Two special names, "dv" and "da" specify
7201 respectively the default (best suited) video and audio stream. Default
7202 is "dv", or "da" if the filter is called as "amovie".
7204 @item stream_index, si
7205 Specifies the index of the video stream to read. If the value is -1,
7206 the best suited video stream will be automatically selected. Default
7207 value is "-1". Deprecated. If the filter is called "amovie", it will select
7208 audio instead of video.
7211 Specifies how many times to read the stream in sequence.
7212 If the value is less than 1, the stream will be read again and again.
7213 Default value is "1".
7215 Note that when the movie is looped the source timestamps are not
7216 changed, so it will generate non monotonically increasing timestamps.
7219 This filter allows to overlay a second video on top of main input of
7220 a filtergraph as shown in this graph:
7222 input -----------> deltapts0 --> overlay --> output
7225 movie --> scale--> deltapts1 -------+
7228 @subsection Examples
7232 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
7233 on top of the input labelled as "in":
7235 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
7236 [in] setpts=PTS-STARTPTS [main];
7237 [main][over] overlay=16:16 [out]
7241 Read from a video4linux2 device, and overlay it on top of the input
7244 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
7245 [in] setpts=PTS-STARTPTS [main];
7246 [main][over] overlay=16:16 [out]
7250 Read the first video stream and the audio stream with id 0x81 from
7251 dvd.vob; the video is connected to the pad named "video" and the audio is
7252 connected to the pad named "audio":
7254 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
7258 @c man end MULTIMEDIA SOURCES