1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 In libavfilter, it is possible for filters to have multiple inputs and
8 To illustrate the sorts of things that are possible, we can
9 use a complex filter graph. For example, the following one:
12 input --> split ---------------------> overlay --> output
15 +-----> crop --> vflip -------+
18 splits the stream in two streams, sends one stream through the crop filter
19 and the vflip filter before merging it back with the other stream by
20 overlaying it on top. You can use the following command to achieve this:
23 ffmpeg -i input -vf "[in] split [T1], [T2] overlay=0:H/2 [out]; [T1] crop=iw:ih/2:0:ih/2, vflip [T2]" output
26 The result will be that in output the top half of the video is mirrored
29 Filters are loaded using the @var{-vf} or @var{-af} option passed to
30 @command{ffmpeg} or to @command{ffplay}. Filters in the same linear
31 chain are separated by commas. In our example, @var{split,
32 overlay} are in one linear chain, and @var{crop, vflip} are in
33 another. The points where the linear chains join are labeled by names
34 enclosed in square brackets. In our example, that is @var{[T1]} and
35 @var{[T2]}. The special labels @var{[in]} and @var{[out]} are the points
36 where video is input and output.
38 Some filters take in input a list of parameters: they are specified
39 after the filter name and an equal sign, and are separated from each other
42 There exist so-called @var{source filters} that do not have an
43 audio/video input, and @var{sink filters} that will not have audio/video
46 @c man end FILTERING INTRODUCTION
49 @c man begin GRAPH2DOT
51 The @file{graph2dot} program included in the FFmpeg @file{tools}
52 directory can be used to parse a filter graph description and issue a
53 corresponding textual representation in the dot language.
60 to see how to use @file{graph2dot}.
62 You can then pass the dot description to the @file{dot} program (from
63 the graphviz suite of programs) and obtain a graphical representation
66 For example the sequence of commands:
68 echo @var{GRAPH_DESCRIPTION} | \
69 tools/graph2dot -o graph.tmp && \
70 dot -Tpng graph.tmp -o graph.png && \
74 can be used to create and display an image representing the graph
75 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
76 a complete self-contained graph, with its inputs and outputs explicitly defined.
77 For example if your command line is of the form:
79 ffmpeg -i infile -vf scale=640:360 outfile
81 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
83 nullsrc,scale=640:360,nullsink
85 you may also need to set the @var{nullsrc} parameters and add a @var{format}
86 filter in order to simulate a specific input file.
90 @chapter Filtergraph description
91 @c man begin FILTERGRAPH DESCRIPTION
93 A filtergraph is a directed graph of connected filters. It can contain
94 cycles, and there can be multiple links between a pair of
95 filters. Each link has one input pad on one side connecting it to one
96 filter from which it takes its input, and one output pad on the other
97 side connecting it to the one filter accepting its output.
99 Each filter in a filtergraph is an instance of a filter class
100 registered in the application, which defines the features and the
101 number of input and output pads of the filter.
103 A filter with no input pads is called a "source", a filter with no
104 output pads is called a "sink".
106 @anchor{Filtergraph syntax}
107 @section Filtergraph syntax
109 A filtergraph can be represented using a textual representation, which is
110 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
111 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
112 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
113 @file{libavfilter/avfiltergraph.h}.
115 A filterchain consists of a sequence of connected filters, each one
116 connected to the previous one in the sequence. A filterchain is
117 represented by a list of ","-separated filter descriptions.
119 A filtergraph consists of a sequence of filterchains. A sequence of
120 filterchains is represented by a list of ";"-separated filterchain
123 A filter is represented by a string of the form:
124 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
126 @var{filter_name} is the name of the filter class of which the
127 described filter is an instance of, and has to be the name of one of
128 the filter classes registered in the program.
129 The name of the filter class is optionally followed by a string
132 @var{arguments} is a string which contains the parameters used to
133 initialize the filter instance, and are described in the filter
136 The list of arguments can be quoted using the character "'" as initial
137 and ending mark, and the character '\' for escaping the characters
138 within the quoted text; otherwise the argument string is considered
139 terminated when the next special character (belonging to the set
140 "[]=;,") is encountered.
142 The name and arguments of the filter are optionally preceded and
143 followed by a list of link labels.
144 A link label allows to name a link and associate it to a filter output
145 or input pad. The preceding labels @var{in_link_1}
146 ... @var{in_link_N}, are associated to the filter input pads,
147 the following labels @var{out_link_1} ... @var{out_link_M}, are
148 associated to the output pads.
150 When two link labels with the same name are found in the
151 filtergraph, a link between the corresponding input and output pad is
154 If an output pad is not labelled, it is linked by default to the first
155 unlabelled input pad of the next filter in the filterchain.
156 For example in the filterchain:
158 nullsrc, split[L1], [L2]overlay, nullsink
160 the split filter instance has two output pads, and the overlay filter
161 instance two input pads. The first output pad of split is labelled
162 "L1", the first input pad of overlay is labelled "L2", and the second
163 output pad of split is linked to the second input pad of overlay,
164 which are both unlabelled.
166 In a complete filterchain all the unlabelled filter input and output
167 pads must be connected. A filtergraph is considered valid if all the
168 filter input and output pads of all the filterchains are connected.
170 Libavfilter will automatically insert scale filters where format
171 conversion is required. It is possible to specify swscale flags
172 for those automatically inserted scalers by prepending
173 @code{sws_flags=@var{flags};}
174 to the filtergraph description.
176 Follows a BNF description for the filtergraph syntax:
178 @var{NAME} ::= sequence of alphanumeric characters and '_'
179 @var{LINKLABEL} ::= "[" @var{NAME} "]"
180 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
181 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
182 @var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
183 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
184 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
187 @section Notes on filtergraph escaping
189 Some filter arguments require the use of special characters, typically
190 @code{:} to separate key=value pairs in a named options list. In this
191 case the user should perform a first level escaping when specifying
192 the filter arguments. For example, consider the following literal
193 string to be embedded in the @ref{drawtext} filter arguments:
195 this is a 'string': may contain one, or more, special characters
198 Since @code{:} is special for the filter arguments syntax, it needs to
199 be escaped, so you get:
201 text=this is a \'string\'\: may contain one, or more, special characters
204 A second level of escaping is required when embedding the filter
205 arguments in a filtergraph description, in order to escape all the
206 filtergraph special characters. Thus the example above becomes:
208 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
211 Finally an additional level of escaping may be needed when writing the
212 filtergraph description in a shell command, which depends on the
213 escaping rules of the adopted shell. For example, assuming that
214 @code{\} is special and needs to be escaped with another @code{\}, the
215 previous string will finally result in:
217 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
220 Sometimes, it might be more convenient to employ quoting in place of
221 escaping. For example the string:
223 Caesar: tu quoque, Brute, fili mi
226 Can be quoted in the filter arguments as:
228 text='Caesar: tu quoque, Brute, fili mi'
231 And finally inserted in a filtergraph like:
233 drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
236 See the ``Quoting and escaping'' section in the ffmpeg-utils manual
237 for more information about the escaping and quoting rules adopted by
240 @c man end FILTERGRAPH DESCRIPTION
242 @chapter Audio Filters
243 @c man begin AUDIO FILTERS
245 When you configure your FFmpeg build, you can disable any of the
246 existing filters using @code{--disable-filters}.
247 The configure output will show the audio filters included in your
250 Below is a description of the currently available audio filters.
254 Convert the input audio format to the specified formats.
256 The filter accepts a string of the form:
257 "@var{sample_format}:@var{channel_layout}".
259 @var{sample_format} specifies the sample format, and can be a string or the
260 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
261 suffix for a planar sample format.
263 @var{channel_layout} specifies the channel layout, and can be a string
264 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
266 The special parameter "auto", signifies that the filter will
267 automatically select the output format depending on the output filter.
269 Some examples follow.
273 Convert input to float, planar, stereo:
279 Convert input to unsigned 8-bit, automatically select out channel layout:
287 Apply a two-pole all-pass filter with central frequency (in Hz)
288 @var{frequency}, and filter-width @var{width}.
289 An all-pass filter changes the audio's frequency to phase relationship
290 without changing its frequency to amplitude relationship.
292 The filter accepts parameters as a list of @var{key}=@var{value}
293 pairs, separated by ":".
295 A description of the accepted parameters follows.
302 Set method to specify band-width of filter.
305 @item @var{q} (Q-Factor)
306 @item @var{o} (octave)
307 @item @var{s} (slope)
311 Specify the band-width of a filter in width_type units.
316 Apply a high-pass filter with 3dB point frequency.
317 The filter can be either single-pole, or double-pole (the default).
318 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
320 The filter accepts parameters as a list of @var{key}=@var{value}
321 pairs, separated by ":".
323 A description of the accepted parameters follows.
327 Set frequency in Hz. Default is 3000.
330 Set number of poles. Default is 2.
333 Set method to specify band-width of filter.
336 @item @var{q} (Q-Factor)
337 @item @var{o} (octave)
338 @item @var{s} (slope)
342 Specify the band-width of a filter in width_type units.
343 Applies only to double-pole filter.
344 The default is 0.707q and gives a Butterworth response.
349 Apply a low-pass filter with 3dB point frequency.
350 The filter can be either single-pole or double-pole (the default).
351 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
353 The filter accepts parameters as a list of @var{key}=@var{value}
354 pairs, separated by ":".
356 A description of the accepted parameters follows.
360 Set frequency in Hz. Default is 500.
363 Set number of poles. Default is 2.
366 Set method to specify band-width of filter.
369 @item @var{q} (Q-Factor)
370 @item @var{o} (octave)
371 @item @var{s} (slope)
375 Specify the band-width of a filter in width_type units.
376 Applies only to double-pole filter.
377 The default is 0.707q and gives a Butterworth response.
382 Boost or cut the bass (lower) frequencies of the audio using a two-pole
383 shelving filter with a response similar to that of a standard
384 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
386 The filter accepts parameters as a list of @var{key}=@var{value}
387 pairs, separated by ":".
389 A description of the accepted parameters follows.
393 Give the gain at 0 Hz. Its useful range is about -20
394 (for a large cut) to +20 (for a large boost).
395 Beware of clipping when using a positive gain.
398 Set the filter's central frequency and so can be used
399 to extend or reduce the frequency range to be boosted or cut.
400 The default value is @code{100} Hz.
403 Set method to specify band-width of filter.
406 @item @var{q} (Q-Factor)
407 @item @var{o} (octave)
408 @item @var{s} (slope)
412 Determine how steep is the filter's shelf transition.
417 Boost or cut treble (upper) frequencies of the audio using a two-pole
418 shelving filter with a response similar to that of a standard
419 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
421 The filter accepts parameters as a list of @var{key}=@var{value}
422 pairs, separated by ":".
424 A description of the accepted parameters follows.
428 Give the gain at whichever is the lower of ~22 kHz and the
429 Nyquist frequency. Its useful range is about -20 (for a large cut)
430 to +20 (for a large boost). Beware of clipping when using a positive gain.
433 Set the filter's central frequency and so can be used
434 to extend or reduce the frequency range to be boosted or cut.
435 The default value is @code{3000} Hz.
438 Set method to specify band-width of filter.
441 @item @var{q} (Q-Factor)
442 @item @var{o} (octave)
443 @item @var{s} (slope)
447 Determine how steep is the filter's shelf transition.
452 Apply a two-pole Butterworth band-pass filter with central
453 frequency @var{frequency}, and (3dB-point) band-width width.
454 The @var{csg} option selects a constant skirt gain (peak gain = Q)
455 instead of the default: constant 0dB peak gain.
456 The filter roll off at 6dB per octave (20dB per decade).
458 The filter accepts parameters as a list of @var{key}=@var{value}
459 pairs, separated by ":".
461 A description of the accepted parameters follows.
465 Set the filter's central frequency. Default is @code{3000}.
468 Constant skirt gain if set to 1. Defaults to 0.
471 Set method to specify band-width of filter.
474 @item @var{q} (Q-Factor)
475 @item @var{o} (octave)
476 @item @var{s} (slope)
480 Specify the band-width of a filter in width_type units.
485 Apply a two-pole Butterworth band-reject filter with central
486 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
487 The filter roll off at 6dB per octave (20dB per decade).
489 The filter accepts parameters as a list of @var{key}=@var{value}
490 pairs, separated by ":".
492 A description of the accepted parameters follows.
496 Set the filter's central frequency. Default is @code{3000}.
499 Set method to specify band-width of filter.
502 @item @var{q} (Q-Factor)
503 @item @var{o} (octave)
504 @item @var{s} (slope)
508 Specify the band-width of a filter in width_type units.
513 Apply a biquad IIR filter with the given coefficients.
514 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
515 are the numerator and denominator coefficients respectively.
519 Apply a two-pole peaking equalisation (EQ) filter. With this
520 filter, the signal-level at and around a selected frequency can
521 be increased or decreased, whilst (unlike bandpass and bandreject
522 filters) that at all other frequencies is unchanged.
524 In order to produce complex equalisation curves, this filter can
525 be given several times, each with a different central frequency.
527 The filter accepts parameters as a list of @var{key}=@var{value}
528 pairs, separated by ":".
530 A description of the accepted parameters follows.
534 Set the filter's central frequency in Hz.
537 Set method to specify band-width of filter.
540 @item @var{q} (Q-Factor)
541 @item @var{o} (octave)
542 @item @var{s} (slope)
546 Specify the band-width of a filter in width_type units.
549 Set the required gain or attenuation in dB.
550 Beware of clipping when using a positive gain.
555 Apply fade-in/out effect to input audio.
557 The filter accepts parameters as a list of @var{key}=@var{value}
558 pairs, separated by ":".
560 A description of the accepted parameters follows.
564 Specify the effect type, can be either @code{in} for fade-in, or
565 @code{out} for a fade-out effect. Default is @code{in}.
567 @item start_sample, ss
568 Specify the number of the start sample for starting to apply the fade
569 effect. Default is 0.
572 Specify the number of samples for which the fade effect has to last. At
573 the end of the fade-in effect the output audio will have the same
574 volume as the input audio, at the end of the fade-out transition
575 the output audio will be silence. Default is 44100.
578 Specify time in seconds for starting to apply the fade
579 effect. Default is 0.
580 If set this option is used instead of @var{start_sample} one.
583 Specify the number of seconds for which the fade effect has to last. At
584 the end of the fade-in effect the output audio will have the same
585 volume as the input audio, at the end of the fade-out transition
586 the output audio will be silence. Default is 0.
587 If set this option is used instead of @var{nb_samples} one.
590 Set cuve for fade transition.
592 @item @var{tri} (triangular, linear slope (default))
593 @item @var{qsin} (quarter of sine wave)
594 @item @var{hsin} (half of sine wave)
595 @item @var{esin} (exponential sine wave)
596 @item @var{log} (logarithmic)
597 @item @var{par} (inverted parabola)
598 @item @var{qua} (quadratic)
599 @item @var{cub} (cubic)
600 @item @var{squ} (square root)
601 @item @var{cbr} (cubic root)
608 Fade in first 15 seconds of audio:
614 Fade out last 25 seconds of a 900 seconds audio:
616 afade=t=out:ss=875:d=25
622 Set output format constraints for the input audio. The framework will
623 negotiate the most appropriate format to minimize conversions.
625 The filter accepts the following named parameters:
629 A comma-separated list of requested sample formats.
632 A comma-separated list of requested sample rates.
634 @item channel_layouts
635 A comma-separated list of requested channel layouts.
639 If a parameter is omitted, all values are allowed.
641 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
643 aformat='sample_fmts=u8,s16:channel_layouts=stereo'
648 Merge two or more audio streams into a single multi-channel stream.
650 The filter accepts the following named options:
655 Set the number of inputs. Default is 2.
659 If the channel layouts of the inputs are disjoint, and therefore compatible,
660 the channel layout of the output will be set accordingly and the channels
661 will be reordered as necessary. If the channel layouts of the inputs are not
662 disjoint, the output will have all the channels of the first input then all
663 the channels of the second input, in that order, and the channel layout of
664 the output will be the default value corresponding to the total number of
667 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
668 is FC+BL+BR, then the output will be in 5.1, with the channels in the
669 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
670 first input, b1 is the first channel of the second input).
672 On the other hand, if both input are in stereo, the output channels will be
673 in the default order: a1, a2, b1, b2, and the channel layout will be
674 arbitrarily set to 4.0, which may or may not be the expected value.
676 All inputs must have the same sample rate, and format.
678 If inputs do not have the same duration, the output will stop with the
681 Example: merge two mono files into a stereo stream:
683 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
686 Example: multiple merges:
689 amovie=input.mkv:si=0 [a0];
690 amovie=input.mkv:si=1 [a1];
691 amovie=input.mkv:si=2 [a2];
692 amovie=input.mkv:si=3 [a3];
693 amovie=input.mkv:si=4 [a4];
694 amovie=input.mkv:si=5 [a5];
695 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
700 Mixes multiple audio inputs into a single output.
704 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
706 will mix 3 input audio streams to a single output with the same duration as the
707 first input and a dropout transition time of 3 seconds.
709 The filter accepts the following named parameters:
713 Number of inputs. If unspecified, it defaults to 2.
716 How to determine the end-of-stream.
720 Duration of longest input. (default)
723 Duration of shortest input.
726 Duration of first input.
730 @item dropout_transition
731 Transition time, in seconds, for volume renormalization when an input
732 stream ends. The default value is 2 seconds.
738 Pass the audio source unchanged to the output.
742 Pad the end of a audio stream with silence, this can be used together with
743 -shortest to extend audio streams to the same length as the video stream.
748 Resample the input audio to the specified parameters, using the
749 libswresample library. If none are specified then the filter will
750 automatically convert between its input and output.
752 This filter is also able to stretch/squeeze the audio data to make it match
753 the timestamps or to inject silence / cut out audio to make it match the
754 timestamps, do a combination of both or do neither.
756 The filter accepts the syntax
757 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
758 expresses a sample rate and @var{resampler_options} is a list of
759 @var{key}=@var{value} pairs, separated by ":". See the
760 ffmpeg-resampler manual for the complete list of supported options.
762 For example, to resample the input audio to 44100Hz:
767 To stretch/squeeze samples to the given timestamps, with a maximum of 1000
768 samples per second compensation:
773 @section asetnsamples
775 Set the number of samples per each output audio frame.
777 The last output packet may contain a different number of samples, as
778 the filter will flush all the remaining samples when the input audio
781 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
786 @item nb_out_samples, n
787 Set the number of frames per each output audio frame. The number is
788 intended as the number of samples @emph{per each channel}.
789 Default value is 1024.
792 If set to 1, the filter will pad the last audio frame with zeroes, so
793 that the last frame will contain the same number of samples as the
794 previous ones. Default value is 1.
797 For example, to set the number of per-frame samples to 1234 and
798 disable padding for the last frame, use:
800 asetnsamples=n=1234:p=0
805 Show a line containing various information for each input audio frame.
806 The input audio is not modified.
808 The shown line contains a sequence of key/value pairs of the form
809 @var{key}:@var{value}.
811 A description of each shown parameter follows:
815 sequential number of the input frame, starting from 0
818 Presentation timestamp of the input frame, in time base units; the time base
819 depends on the filter input pad, and is usually 1/@var{sample_rate}.
822 presentation timestamp of the input frame in seconds
825 position of the frame in the input stream, -1 if this information in
826 unavailable and/or meaningless (for example in case of synthetic audio)
835 sample rate for the audio frame
838 number of samples (per channel) in the frame
841 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
842 the data is treated as if all the planes were concatenated.
844 @item plane_checksums
845 A list of Adler-32 checksums for each data plane.
850 Split input audio into several identical outputs.
852 The filter accepts a single parameter which specifies the number of outputs. If
853 unspecified, it defaults to 2.
857 [in] asplit [out0][out1]
860 will create two separate outputs from the same input.
862 To create 3 or more outputs, you need to specify the number of
865 [in] asplit=3 [out0][out1][out2]
869 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
871 will create 5 copies of the input audio.
876 Forward two audio streams and control the order the buffers are forwarded.
878 The argument to the filter is an expression deciding which stream should be
879 forwarded next: if the result is negative, the first stream is forwarded; if
880 the result is positive or zero, the second stream is forwarded. It can use
881 the following variables:
885 number of buffers forwarded so far on each stream
887 number of samples forwarded so far on each stream
889 current timestamp of each stream
892 The default value is @code{t1-t2}, which means to always forward the stream
893 that has a smaller timestamp.
895 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
896 input, while avoiding too much of a desynchronization:
898 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
899 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
907 The filter accepts exactly one parameter, the audio tempo. If not
908 specified then the filter will assume nominal 1.0 tempo. Tempo must
909 be in the [0.5, 2.0] range.
911 For example, to slow down audio to 80% tempo:
916 For example, to speed up audio to 125% tempo:
923 Make audio easier to listen to on headphones.
925 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
926 so that when listened to on headphones the stereo image is moved from
927 inside your head (standard for headphones) to outside and in front of
928 the listener (standard for speakers).
934 Mix channels with specific gain levels. The filter accepts the output
935 channel layout followed by a set of channels definitions.
937 This filter is also designed to remap efficiently the channels of an audio
940 The filter accepts parameters of the form:
941 "@var{l}:@var{outdef}:@var{outdef}:..."
945 output channel layout or number of channels
948 output channel specification, of the form:
949 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
952 output channel to define, either a channel name (FL, FR, etc.) or a channel
953 number (c0, c1, etc.)
956 multiplicative coefficient for the channel, 1 leaving the volume unchanged
959 input channel to use, see out_name for details; it is not possible to mix
960 named and numbered input channels
963 If the `=' in a channel specification is replaced by `<', then the gains for
964 that specification will be renormalized so that the total is 1, thus
965 avoiding clipping noise.
967 @subsection Mixing examples
969 For example, if you want to down-mix from stereo to mono, but with a bigger
970 factor for the left channel:
972 pan=1:c0=0.9*c0+0.1*c1
975 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
978 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
981 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
982 that should be preferred (see "-ac" option) unless you have very specific
985 @subsection Remapping examples
987 The channel remapping will be effective if, and only if:
990 @item gain coefficients are zeroes or ones,
991 @item only one input per channel output,
994 If all these conditions are satisfied, the filter will notify the user ("Pure
995 channel mapping detected"), and use an optimized and lossless method to do the
998 For example, if you have a 5.1 source and want a stereo audio stream by
999 dropping the extra channels:
1001 pan="stereo: c0=FL : c1=FR"
1004 Given the same source, you can also switch front left and front right channels
1005 and keep the input channel layout:
1007 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1010 If the input is a stereo audio stream, you can mute the front left channel (and
1011 still keep the stereo channel layout) with:
1016 Still with a stereo audio stream input, you can copy the right channel in both
1017 front left and right:
1019 pan="stereo: c0=FR : c1=FR"
1022 @section silencedetect
1024 Detect silence in an audio stream.
1026 This filter logs a message when it detects that the input audio volume is less
1027 or equal to a noise tolerance value for a duration greater or equal to the
1028 minimum detected noise duration.
1030 The printed times and duration are expressed in seconds.
1034 Set silence duration until notification (default is 2 seconds).
1037 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1038 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1041 Detect 5 seconds of silence with -50dB noise tolerance:
1043 silencedetect=n=-50dB:d=5
1046 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1047 tolerance in @file{silence.mp3}:
1049 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
1053 Synchronize audio data with timestamps by squeezing/stretching it and/or
1054 dropping samples/adding silence when needed.
1056 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1058 The filter accepts the following named parameters:
1062 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1063 by default. When disabled, time gaps are covered with silence.
1066 Minimum difference between timestamps and audio data (in seconds) to trigger
1067 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1068 this filter, try setting this parameter to 0.
1071 Maximum compensation in samples per second. Relevant only with compensate=1.
1075 Assume the first pts should be this value. The time base is 1 / sample rate.
1076 This allows for padding/trimming at the start of stream. By default, no
1077 assumption is made about the first frame's expected pts, so no padding or
1078 trimming is done. For example, this could be set to 0 to pad the beginning with
1079 silence if an audio stream starts after the video stream or to trim any samples
1080 with a negative pts due to encoder delay.
1084 @section channelsplit
1085 Split each channel in input audio stream into a separate output stream.
1087 This filter accepts the following named parameters:
1089 @item channel_layout
1090 Channel layout of the input stream. Default is "stereo".
1093 For example, assuming a stereo input MP3 file
1095 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1097 will create an output Matroska file with two audio streams, one containing only
1098 the left channel and the other the right channel.
1100 To split a 5.1 WAV file into per-channel files
1102 ffmpeg -i in.wav -filter_complex
1103 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1104 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1105 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1110 Remap input channels to new locations.
1112 This filter accepts the following named parameters:
1114 @item channel_layout
1115 Channel layout of the output stream.
1118 Map channels from input to output. The argument is a comma-separated list of
1119 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1120 @var{in_channel} form. @var{in_channel} can be either the name of the input
1121 channel (e.g. FL for front left) or its index in the input channel layout.
1122 @var{out_channel} is the name of the output channel or its index in the output
1123 channel layout. If @var{out_channel} is not given then it is implicitly an
1124 index, starting with zero and increasing by one for each mapping.
1127 If no mapping is present, the filter will implicitly map input channels to
1128 output channels preserving index.
1130 For example, assuming a 5.1+downmix input MOV file
1132 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
1134 will create an output WAV file tagged as stereo from the downmix channels of
1137 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1139 ffmpeg -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
1143 Join multiple input streams into one multi-channel stream.
1145 The filter accepts the following named parameters:
1149 Number of input streams. Defaults to 2.
1151 @item channel_layout
1152 Desired output channel layout. Defaults to stereo.
1155 Map channels from inputs to output. The argument is a comma-separated list of
1156 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1157 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1158 can be either the name of the input channel (e.g. FL for front left) or its
1159 index in the specified input stream. @var{out_channel} is the name of the output
1163 The filter will attempt to guess the mappings when those are not specified
1164 explicitly. It does so by first trying to find an unused matching input channel
1165 and if that fails it picks the first unused input channel.
1167 E.g. to join 3 inputs (with properly set channel layouts)
1169 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1172 To build a 5.1 output from 6 single-channel streams:
1174 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1175 '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'
1180 Convert the audio sample format, sample rate and channel layout. This filter is
1181 not meant to be used directly.
1185 Adjust the input audio volume.
1187 The filter accepts the following named parameters. If the key of the
1188 first options is omitted, the arguments are interpreted according to
1189 the following syntax:
1191 volume=@var{volume}:@var{precision}
1197 Expresses how the audio volume will be increased or decreased.
1199 Output values are clipped to the maximum value.
1201 The output audio volume is given by the relation:
1203 @var{output_volume} = @var{volume} * @var{input_volume}
1206 Default value for @var{volume} is 1.0.
1209 Set the mathematical precision.
1211 This determines which input sample formats will be allowed, which affects the
1212 precision of the volume scaling.
1216 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1218 32-bit floating-point; limits input sample format to FLT. (default)
1220 64-bit floating-point; limits input sample format to DBL.
1224 @subsection Examples
1228 Halve the input audio volume:
1232 volume=volume=-6.0206dB
1235 In all the above example the named key for @option{volume} can be
1236 omitted, for example like in:
1242 Increase input audio power by 6 decibels using fixed-point precision:
1244 volume=volume=6dB:precision=fixed
1248 @section volumedetect
1250 Detect the volume of the input video.
1252 The filter has no parameters. The input is not modified. Statistics about
1253 the volume will be printed in the log when the input stream end is reached.
1255 In particular it will show the mean volume (root mean square), maximum
1256 volume (on a per-sample basis), and the beginning of an histogram of the
1257 registered volume values (from the maximum value to a cumulated 1/1000 of
1260 All volumes are in decibels relative to the maximum PCM value.
1262 Here is an excerpt of the output:
1264 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1265 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1266 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1267 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1268 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1269 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1270 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1271 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1272 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1278 The mean square energy is approximately -27 dB, or 10^-2.7.
1280 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1282 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1285 In other words, raising the volume by +4 dB does not cause any clipping,
1286 raising it by +5 dB causes clipping for 6 samples, etc.
1288 @c man end AUDIO FILTERS
1290 @chapter Audio Sources
1291 @c man begin AUDIO SOURCES
1293 Below is a description of the currently available audio sources.
1297 Buffer audio frames, and make them available to the filter chain.
1299 This source is mainly intended for a programmatic use, in particular
1300 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1302 It accepts the following mandatory parameters:
1303 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
1308 The sample rate of the incoming audio buffers.
1311 The sample format of the incoming audio buffers.
1312 Either a sample format name or its corresponging integer representation from
1313 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1315 @item channel_layout
1316 The channel layout of the incoming audio buffers.
1317 Either a channel layout name from channel_layout_map in
1318 @file{libavutil/channel_layout.c} or its corresponding integer representation
1319 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1322 The number of channels of the incoming audio buffers.
1323 If both @var{channels} and @var{channel_layout} are specified, then they
1330 abuffer=44100:s16p:stereo
1333 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1334 Since the sample format with name "s16p" corresponds to the number
1335 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1343 Generate an audio signal specified by an expression.
1345 This source accepts in input one or more expressions (one for each
1346 channel), which are evaluated and used to generate a corresponding
1349 It accepts the syntax: @var{exprs}[::@var{options}].
1350 @var{exprs} is a list of expressions separated by ":", one for each
1351 separate channel. In case the @var{channel_layout} is not
1352 specified, the selected channel layout depends on the number of
1353 provided expressions.
1355 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1358 The description of the accepted options follows.
1362 @item channel_layout, c
1363 Set the channel layout. The number of channels in the specified layout
1364 must be equal to the number of specified expressions.
1367 Set the minimum duration of the sourced audio. See the function
1368 @code{av_parse_time()} for the accepted format.
1369 Note that the resulting duration may be greater than the specified
1370 duration, as the generated audio is always cut at the end of a
1373 If not specified, or the expressed duration is negative, the audio is
1374 supposed to be generated forever.
1377 Set the number of samples per channel per each output frame,
1380 @item sample_rate, s
1381 Specify the sample rate, default to 44100.
1384 Each expression in @var{exprs} can contain the following constants:
1388 number of the evaluated sample, starting from 0
1391 time of the evaluated sample expressed in seconds, starting from 0
1398 @subsection Examples
1410 Generate a sin signal with frequency of 440 Hz, set sample rate to
1413 aevalsrc="sin(440*2*PI*t)::s=8000"
1417 Generate a two channels signal, specify the channel layout (Front
1418 Center + Back Center) explicitly:
1420 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1424 Generate white noise:
1426 aevalsrc="-2+random(0)"
1430 Generate an amplitude modulated signal:
1432 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1436 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1438 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1445 Null audio source, return unprocessed audio frames. It is mainly useful
1446 as a template and to be employed in analysis / debugging tools, or as
1447 the source for filters which ignore the input data (for example the sox
1450 It accepts an optional sequence of @var{key}=@var{value} pairs,
1453 The description of the accepted options follows.
1457 @item sample_rate, s
1458 Specify the sample rate, and defaults to 44100.
1460 @item channel_layout, cl
1462 Specify the channel layout, and can be either an integer or a string
1463 representing a channel layout. The default value of @var{channel_layout}
1466 Check the channel_layout_map definition in
1467 @file{libavutil/channel_layout.c} for the mapping between strings and
1468 channel layout values.
1471 Set the number of samples per requested frames.
1475 Follow some examples:
1477 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1478 anullsrc=r=48000:cl=4
1481 anullsrc=r=48000:cl=mono
1485 Buffer audio frames, and make them available to the filter chain.
1487 This source is not intended to be part of user-supplied graph descriptions but
1488 for insertion by calling programs through the interface defined in
1489 @file{libavfilter/buffersrc.h}.
1491 It accepts the following named parameters:
1495 Timebase which will be used for timestamps of submitted frames. It must be
1496 either a floating-point number or in @var{numerator}/@var{denominator} form.
1502 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1504 @item channel_layout
1505 Channel layout of the audio data, in the form that can be accepted by
1506 @code{av_get_channel_layout()}.
1509 All the parameters need to be explicitly defined.
1513 Synthesize a voice utterance using the libflite library.
1515 To enable compilation of this filter you need to configure FFmpeg with
1516 @code{--enable-libflite}.
1518 Note that the flite library is not thread-safe.
1520 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1523 The description of the accepted parameters follows.
1528 If set to 1, list the names of the available voices and exit
1529 immediately. Default value is 0.
1532 Set the maximum number of samples per frame. Default value is 512.
1535 Set the filename containing the text to speak.
1538 Set the text to speak.
1541 Set the voice to use for the speech synthesis. Default value is
1542 @code{kal}. See also the @var{list_voices} option.
1545 @subsection Examples
1549 Read from file @file{speech.txt}, and synthetize the text using the
1550 standard flite voice:
1552 flite=textfile=speech.txt
1556 Read the specified text selecting the @code{slt} voice:
1558 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1562 Input text to ffmpeg:
1564 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1568 Make @file{ffplay} speak the specified text, using @code{flite} and
1569 the @code{lavfi} device:
1571 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1575 For more information about libflite, check:
1576 @url{http://www.speech.cs.cmu.edu/flite/}
1578 @c man end AUDIO SOURCES
1580 @chapter Audio Sinks
1581 @c man begin AUDIO SINKS
1583 Below is a description of the currently available audio sinks.
1585 @section abuffersink
1587 Buffer audio frames, and make them available to the end of filter chain.
1589 This sink is mainly intended for programmatic use, in particular
1590 through the interface defined in @file{libavfilter/buffersink.h}.
1592 It requires a pointer to an AVABufferSinkContext structure, which
1593 defines the incoming buffers' formats, to be passed as the opaque
1594 parameter to @code{avfilter_init_filter} for initialization.
1598 Null audio sink, do absolutely nothing with the input audio. It is
1599 mainly useful as a template and to be employed in analysis / debugging
1602 @section abuffersink
1603 This sink is intended for programmatic use. Frames that arrive on this sink can
1604 be retrieved by the calling program using the interface defined in
1605 @file{libavfilter/buffersink.h}.
1607 This filter accepts no parameters.
1609 @c man end AUDIO SINKS
1611 @chapter Video Filters
1612 @c man begin VIDEO FILTERS
1614 When you configure your FFmpeg build, you can disable any of the
1615 existing filters using @code{--disable-filters}.
1616 The configure output will show the video filters included in your
1619 Below is a description of the currently available video filters.
1621 @section alphaextract
1623 Extract the alpha component from the input as a grayscale video. This
1624 is especially useful with the @var{alphamerge} filter.
1628 Add or replace the alpha component of the primary input with the
1629 grayscale value of a second input. This is intended for use with
1630 @var{alphaextract} to allow the transmission or storage of frame
1631 sequences that have alpha in a format that doesn't support an alpha
1634 For example, to reconstruct full frames from a normal YUV-encoded video
1635 and a separate video created with @var{alphaextract}, you might use:
1637 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1640 Since this filter is designed for reconstruction, it operates on frame
1641 sequences without considering timestamps, and terminates when either
1642 input reaches end of stream. This will cause problems if your encoding
1643 pipeline drops frames. If you're trying to apply an image as an
1644 overlay to a video stream, consider the @var{overlay} filter instead.
1648 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1649 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1650 Substation Alpha) subtitles files.
1654 Compute the bounding box for the non-black pixels in the input frame
1657 This filter computes the bounding box containing all the pixels with a
1658 luminance value greater than the minimum allowed value.
1659 The parameters describing the bounding box are printed on the filter
1662 @section blackdetect
1664 Detect video intervals that are (almost) completely black. Can be
1665 useful to detect chapter transitions, commercials, or invalid
1666 recordings. Output lines contains the time for the start, end and
1667 duration of the detected black interval expressed in seconds.
1669 In order to display the output lines, you need to set the loglevel at
1670 least to the AV_LOG_INFO value.
1672 This filter accepts a list of options in the form of
1673 @var{key}=@var{value} pairs separated by ":". A description of the
1674 accepted options follows.
1677 @item black_min_duration, d
1678 Set the minimum detected black duration expressed in seconds. It must
1679 be a non-negative floating point number.
1681 Default value is 2.0.
1683 @item picture_black_ratio_th, pic_th
1684 Set the threshold for considering a picture "black".
1685 Express the minimum value for the ratio:
1687 @var{nb_black_pixels} / @var{nb_pixels}
1690 for which a picture is considered black.
1691 Default value is 0.98.
1693 @item pixel_black_th, pix_th
1694 Set the threshold for considering a pixel "black".
1696 The threshold expresses the maximum pixel luminance value for which a
1697 pixel is considered "black". The provided value is scaled according to
1698 the following equation:
1700 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1703 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1704 the input video format, the range is [0-255] for YUV full-range
1705 formats and [16-235] for YUV non full-range formats.
1707 Default value is 0.10.
1710 The following example sets the maximum pixel threshold to the minimum
1711 value, and detects only black intervals of 2 or more seconds:
1713 blackdetect=d=2:pix_th=0.00
1718 Detect frames that are (almost) completely black. Can be useful to
1719 detect chapter transitions or commercials. Output lines consist of
1720 the frame number of the detected frame, the percentage of blackness,
1721 the position in the file if known or -1 and the timestamp in seconds.
1723 In order to display the output lines, you need to set the loglevel at
1724 least to the AV_LOG_INFO value.
1726 The filter accepts the syntax:
1728 blackframe[=@var{amount}:[@var{threshold}]]
1731 @var{amount} is the percentage of the pixels that have to be below the
1732 threshold, and defaults to 98.
1734 @var{threshold} is the threshold below which a pixel value is
1735 considered black, and defaults to 32.
1739 Apply boxblur algorithm to the input video.
1741 This filter accepts the parameters:
1742 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
1744 Chroma and alpha parameters are optional, if not specified they default
1745 to the corresponding values set for @var{luma_radius} and
1748 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
1749 the radius in pixels of the box used for blurring the corresponding
1750 input plane. They are expressions, and can contain the following
1754 the input width and height in pixels
1757 the input chroma image width and height in pixels
1760 horizontal and vertical chroma subsample values. For example for the
1761 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1764 The radius must be a non-negative number, and must not be greater than
1765 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
1766 and of @code{min(cw,ch)/2} for the chroma planes.
1768 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
1769 how many times the boxblur filter is applied to the corresponding
1772 Some examples follow:
1777 Apply a boxblur filter with luma, chroma, and alpha radius
1784 Set luma radius to 2, alpha and chroma radius to 0
1790 Set luma and chroma radius to a fraction of the video dimension
1792 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
1797 @section colormatrix
1799 The colormatrix filter allows conversion between any of the following color
1800 space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m})
1801 and FCC (@var{fcc}).
1803 The syntax of the parameters is @var{source}:@var{destination}:
1806 colormatrix=bt601:smpte240m
1811 Copy the input source unchanged to the output. Mainly useful for
1816 Crop the input video.
1818 This filter accepts a list of @var{key}=@var{value} pairs as argument,
1819 separated by ':'. If the key of the first options is omitted, the
1820 arguments are interpreted according to the syntax
1821 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
1823 A description of the accepted options follows:
1826 Set the crop area width. It defaults to @code{iw}.
1827 This expression is evaluated only once during the filter
1831 Set the crop area width. It defaults to @code{ih}.
1832 This expression is evaluated only once during the filter
1836 Set the expression for the x top-left coordinate of the cropped area.
1837 It defaults to @code{(in_w-out_w)/2}.
1838 This expression is evaluated per-frame.
1841 Set the expression for the y top-left coordinate of the cropped area.
1842 It defaults to @code{(in_h-out_h)/2}.
1843 This expression is evaluated per-frame.
1846 If set to 1 will force the output display aspect ratio
1847 to be the same of the input, by changing the output sample aspect
1848 ratio. It defaults to 0.
1851 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
1852 expressions containing the following constants:
1856 the computed values for @var{x} and @var{y}. They are evaluated for
1860 the input width and height
1863 same as @var{in_w} and @var{in_h}
1866 the output (cropped) width and height
1869 same as @var{out_w} and @var{out_h}
1872 same as @var{iw} / @var{ih}
1875 input sample aspect ratio
1878 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1881 horizontal and vertical chroma subsample values. For example for the
1882 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1885 the number of input frame, starting from 0
1888 the position in the file of the input frame, NAN if unknown
1891 timestamp expressed in seconds, NAN if the input timestamp is unknown
1895 The expression for @var{out_w} may depend on the value of @var{out_h},
1896 and the expression for @var{out_h} may depend on @var{out_w}, but they
1897 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
1898 evaluated after @var{out_w} and @var{out_h}.
1900 The @var{x} and @var{y} parameters specify the expressions for the
1901 position of the top-left corner of the output (non-cropped) area. They
1902 are evaluated for each frame. If the evaluated value is not valid, it
1903 is approximated to the nearest valid value.
1905 The expression for @var{x} may depend on @var{y}, and the expression
1906 for @var{y} may depend on @var{x}.
1908 @subsection Examples
1911 Crop area with size 100x100 at position (12,34).
1916 Using named options, the example above becomes:
1918 crop=w=100:h=100:x=12:y=34
1922 Crop the central input area with size 100x100:
1928 Crop the central input area with size 2/3 of the input video:
1930 crop=2/3*in_w:2/3*in_h
1934 Crop the input video central square:
1940 Delimit the rectangle with the top-left corner placed at position
1941 100:100 and the right-bottom corner corresponding to the right-bottom
1942 corner of the input image:
1944 crop=in_w-100:in_h-100:100:100
1948 Crop 10 pixels from the left and right borders, and 20 pixels from
1949 the top and bottom borders
1951 crop=in_w-2*10:in_h-2*20
1955 Keep only the bottom right quarter of the input image:
1957 crop=in_w/2:in_h/2:in_w/2:in_h/2
1961 Crop height for getting Greek harmony:
1963 crop=in_w:1/PHI*in_w
1967 Appply trembling effect:
1969 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)
1973 Apply erratic camera effect depending on timestamp:
1975 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)"
1979 Set x depending on the value of y:
1981 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
1987 Auto-detect crop size.
1989 Calculate necessary cropping parameters and prints the recommended
1990 parameters through the logging system. The detected dimensions
1991 correspond to the non-black area of the input video.
1993 It accepts the syntax:
1995 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
2001 Threshold, which can be optionally specified from nothing (0) to
2002 everything (255), defaults to 24.
2005 Value which the width/height should be divisible by, defaults to
2006 16. The offset is automatically adjusted to center the video. Use 2 to
2007 get only even dimensions (needed for 4:2:2 video). 16 is best when
2008 encoding to most video codecs.
2011 Counter that determines after how many frames cropdetect will reset
2012 the previously detected largest video area and start over to detect
2013 the current optimal crop area. Defaults to 0.
2015 This can be useful when channel logos distort the video area. 0
2016 indicates never reset and return the largest area encountered during
2022 This filter drops frames that do not differ greatly from the previous
2023 frame in order to reduce framerate. The main use of this filter is
2024 for very-low-bitrate encoding (e.g. streaming over dialup modem), but
2025 it could in theory be used for fixing movies that were
2026 inverse-telecined incorrectly.
2028 It accepts the following parameters:
2029 @var{max}:@var{hi}:@var{lo}:@var{frac}.
2034 Set the maximum number of consecutive frames which can be dropped (if
2035 positive), or the minimum interval between dropped frames (if
2036 negative). If the value is 0, the frame is dropped unregarding the
2037 number of previous sequentially dropped frames.
2042 Set the dropping threshold values.
2044 Values for @var{hi} and @var{lo} are for 8x8 pixel blocks and
2045 represent actual pixel value differences, so a threshold of 64
2046 corresponds to 1 unit of difference for each pixel, or the same spread
2047 out differently over the block.
2049 A frame is a candidate for dropping if no 8x8 blocks differ by more
2050 than a threshold of @var{hi}, and if no more than @var{frac} blocks (1
2051 meaning the whole image) differ by more than a threshold of @var{lo}.
2053 Default value for @var{hi} is 64*12, default value for @var{lo} is
2054 64*5, and default value for @var{frac} is 0.33.
2059 Suppress a TV station logo by a simple interpolation of the surrounding
2060 pixels. Just set a rectangle covering the logo and watch it disappear
2061 (and sometimes something even uglier appear - your mileage may vary).
2063 The filter accepts parameters as a string of the form
2064 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
2065 @var{key}=@var{value} pairs, separated by ":".
2067 The description of the accepted parameters follows.
2072 Specify the top left corner coordinates of the logo. They must be
2076 Specify the width and height of the logo to clear. They must be
2080 Specify the thickness of the fuzzy edge of the rectangle (added to
2081 @var{w} and @var{h}). The default value is 4.
2084 When set to 1, a green rectangle is drawn on the screen to simplify
2085 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2086 @var{band} is set to 4. The default value is 0.
2090 Some examples follow.
2095 Set a rectangle covering the area with top left corner coordinates 0,0
2096 and size 100x77, setting a band of size 10:
2098 delogo=0:0:100:77:10
2102 As the previous example, but use named options:
2104 delogo=x=0:y=0:w=100:h=77:band=10
2111 Attempt to fix small changes in horizontal and/or vertical shift. This
2112 filter helps remove camera shake from hand-holding a camera, bumping a
2113 tripod, moving on a vehicle, etc.
2115 The filter accepts parameters as a string of the form
2116 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
2118 A description of the accepted parameters follows.
2123 Specify a rectangular area where to limit the search for motion
2125 If desired the search for motion vectors can be limited to a
2126 rectangular area of the frame defined by its top left corner, width
2127 and height. These parameters have the same meaning as the drawbox
2128 filter which can be used to visualise the position of the bounding
2131 This is useful when simultaneous movement of subjects within the frame
2132 might be confused for camera motion by the motion vector search.
2134 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2135 then the full frame is used. This allows later options to be set
2136 without specifying the bounding box for the motion vector search.
2138 Default - search the whole frame.
2141 Specify the maximum extent of movement in x and y directions in the
2142 range 0-64 pixels. Default 16.
2145 Specify how to generate pixels to fill blanks at the edge of the
2146 frame. An integer from 0 to 3 as follows:
2149 Fill zeroes at blank locations
2151 Original image at blank locations
2153 Extruded edge value at blank locations
2155 Mirrored edge at blank locations
2158 The default setting is mirror edge at blank locations.
2161 Specify the blocksize to use for motion search. Range 4-128 pixels,
2165 Specify the contrast threshold for blocks. Only blocks with more than
2166 the specified contrast (difference between darkest and lightest
2167 pixels) will be considered. Range 1-255, default 125.
2170 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
2171 search. Default - exhaustive search.
2174 If set then a detailed log of the motion search is written to the
2181 Draw a colored box on the input image.
2183 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
2186 The description of the accepted parameters follows.
2190 Specify the top left corner coordinates of the box. Default to 0.
2194 Specify the width and height of the box, if 0 they are interpreted as
2195 the input width and height. Default to 0.
2198 Specify the color of the box to write, it can be the name of a color
2199 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2200 value @code{invert} is used, the box edge color is the same as the
2201 video with inverted luma.
2204 Set the thickness of the box edge. Default value is @code{4}.
2207 If the key of the first options is omitted, the arguments are
2208 interpreted according to the syntax
2209 @var{x}:@var{y}:@var{width}:@var{height}:@var{color}:@var{thickness}.
2211 Some examples follow:
2214 Draw a black box around the edge of the input image:
2220 Draw a box with color red and an opacity of 50%:
2222 drawbox=10:20:200:60:red@@0.5
2225 The previous example can be specified as:
2227 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2231 Fill the box with pink color:
2233 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2240 Draw text string or text from specified file on top of video using the
2241 libfreetype library.
2243 To enable compilation of this filter you need to configure FFmpeg with
2244 @code{--enable-libfreetype}.
2248 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
2251 The description of the accepted parameters follows.
2256 Used to draw a box around text using background color.
2257 Value should be either 1 (enable) or 0 (disable).
2258 The default value of @var{box} is 0.
2261 The color to be used for drawing box around text.
2262 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2263 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2264 The default value of @var{boxcolor} is "white".
2267 Set an expression which specifies if the text should be drawn. If the
2268 expression evaluates to 0, the text is not drawn. This is useful for
2269 specifying that the text should be drawn only when specific conditions
2272 Default value is "1".
2274 See below for the list of accepted constants and functions.
2277 Select how the @var{text} is expanded. Can be either @code{none},
2278 @code{strftime} (deprecated) or
2279 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2283 If true, check and fix text coords to avoid clipping.
2286 The color to be used for drawing fonts.
2287 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2288 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2289 The default value of @var{fontcolor} is "black".
2292 The font file to be used for drawing text. Path must be included.
2293 This parameter is mandatory.
2296 The font size to be used for drawing text.
2297 The default value of @var{fontsize} is 16.
2300 Flags to be used for loading the fonts.
2302 The flags map the corresponding flags supported by libfreetype, and are
2303 a combination of the following values:
2310 @item vertical_layout
2311 @item force_autohint
2314 @item ignore_global_advance_width
2316 @item ignore_transform
2323 Default value is "render".
2325 For more information consult the documentation for the FT_LOAD_*
2329 The color to be used for drawing a shadow behind the drawn text. It
2330 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2331 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2332 The default value of @var{shadowcolor} is "black".
2334 @item shadowx, shadowy
2335 The x and y offsets for the text shadow position with respect to the
2336 position of the text. They can be either positive or negative
2337 values. Default value for both is "0".
2340 The size in number of spaces to use for rendering the tab.
2344 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2345 format. It can be used with or without text parameter. @var{timecode_rate}
2346 option must be specified.
2348 @item timecode_rate, rate, r
2349 Set the timecode frame rate (timecode only).
2352 The text string to be drawn. The text must be a sequence of UTF-8
2354 This parameter is mandatory if no file is specified with the parameter
2358 A text file containing text to be drawn. The text must be a sequence
2359 of UTF-8 encoded characters.
2361 This parameter is mandatory if no text string is specified with the
2362 parameter @var{text}.
2364 If both @var{text} and @var{textfile} are specified, an error is thrown.
2367 If set to 1, the @var{textfile} will be reloaded before each frame.
2368 Be sure to update it atomically, or it may be read partially, or even fail.
2371 The expressions which specify the offsets where text will be drawn
2372 within the video frame. They are relative to the top/left border of the
2375 The default value of @var{x} and @var{y} is "0".
2377 See below for the list of accepted constants and functions.
2380 The parameters for @var{x} and @var{y} are expressions containing the
2381 following constants and functions:
2385 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2388 horizontal and vertical chroma subsample values. For example for the
2389 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2392 the height of each text line
2400 @item max_glyph_a, ascent
2401 the maximum distance from the baseline to the highest/upper grid
2402 coordinate used to place a glyph outline point, for all the rendered
2404 It is a positive value, due to the grid's orientation with the Y axis
2407 @item max_glyph_d, descent
2408 the maximum distance from the baseline to the lowest grid coordinate
2409 used to place a glyph outline point, for all the rendered glyphs.
2410 This is a negative value, due to the grid's orientation, with the Y axis
2414 maximum glyph height, that is the maximum height for all the glyphs
2415 contained in the rendered text, it is equivalent to @var{ascent} -
2419 maximum glyph width, that is the maximum width for all the glyphs
2420 contained in the rendered text
2423 the number of input frame, starting from 0
2425 @item rand(min, max)
2426 return a random number included between @var{min} and @var{max}
2429 input sample aspect ratio
2432 timestamp expressed in seconds, NAN if the input timestamp is unknown
2435 the height of the rendered text
2438 the width of the rendered text
2441 the x and y offset coordinates where the text is drawn.
2443 These parameters allow the @var{x} and @var{y} expressions to refer
2444 each other, so you can for example specify @code{y=x/dar}.
2447 If libavfilter was built with @code{--enable-fontconfig}, then
2448 @option{fontfile} can be a fontconfig pattern or omitted.
2450 @anchor{drawtext_expansion}
2451 @subsection Text expansion
2453 If @option{expansion} is set to @code{strftime},
2454 the filter recognizes strftime() sequences in the provided text and
2455 expands them accordingly. Check the documentation of strftime(). This
2456 feature is deprecated.
2458 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2460 If @option{expansion} is set to @code{normal} (which is the default),
2461 the following expansion mechanism is used.
2463 The backslash character '\', followed by any character, always expands to
2464 the second character.
2466 Sequence of the form @code{%@{...@}} are expanded. The text between the
2467 braces is a function name, possibly followed by arguments separated by ':'.
2468 If the arguments contain special characters or delimiters (':' or '@}'),
2469 they should be escaped.
2471 Note that they probably must also be escaped as the value for the
2472 @option{text} option in the filter argument string and as the filter
2473 argument in the filter graph description, and possibly also for the shell,
2474 that makes up to four levels of escaping; using a text file avoids these
2477 The following functions are available:
2482 The expression evaluation result.
2484 It must take one argument specifying the expression to be evaluated,
2485 which accepts the same constants and functions as the @var{x} and
2486 @var{y} values. Note that not all constants should be used, for
2487 example the text size is not known when evaluating the expression, so
2488 the constants @var{text_w} and @var{text_h} will have an undefined
2492 The time at which the filter is running, expressed in UTC.
2493 It can accept an argument: a strftime() format string.
2496 The time at which the filter is running, expressed in the local time zone.
2497 It can accept an argument: a strftime() format string.
2500 The frame number, starting from 0.
2503 The timestamp of the current frame, in seconds, with microsecond accuracy.
2507 @subsection Examples
2509 Some examples follow.
2514 Draw "Test Text" with font FreeSerif, using the default values for the
2515 optional parameters.
2518 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2522 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2523 and y=50 (counting from the top-left corner of the screen), text is
2524 yellow with a red box around it. Both the text and the box have an
2528 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2529 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2532 Note that the double quotes are not necessary if spaces are not used
2533 within the parameter list.
2536 Show the text at the center of the video frame:
2538 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2542 Show a text line sliding from right to left in the last row of the video
2543 frame. The file @file{LONG_LINE} is assumed to contain a single line
2546 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2550 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2552 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2556 Draw a single green letter "g", at the center of the input video.
2557 The glyph baseline is placed at half screen height.
2559 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2563 Show text for 1 second every 3 seconds:
2565 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2569 Use fontconfig to set the font. Note that the colons need to be escaped.
2571 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2575 Print the date of a real-time encoding (see strftime(3)):
2577 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
2582 For more information about libfreetype, check:
2583 @url{http://www.freetype.org/}.
2585 For more information about fontconfig, check:
2586 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
2590 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
2592 This filter accepts the following optional named parameters:
2596 Set low and high threshold values used by the Canny thresholding
2599 The high threshold selects the "strong" edge pixels, which are then
2600 connected through 8-connectivity with the "weak" edge pixels selected
2601 by the low threshold.
2603 @var{low} and @var{high} threshold values must be choosen in the range
2604 [0,1], and @var{low} should be lesser or equal to @var{high}.
2606 Default value for @var{low} is @code{20/255}, and default value for @var{high}
2612 edgedetect=low=0.1:high=0.4
2617 Apply fade-in/out effect to input video.
2619 The filter accepts parameters as a list of @var{key}=@var{value}
2620 pairs, separated by ":". If the key of the first options is omitted,
2621 the arguments are interpreted according to the syntax
2622 @var{type}:@var{start_frame}:@var{nb_frames}.
2624 A description of the accepted parameters follows.
2628 Specify if the effect type, can be either @code{in} for fade-in, or
2629 @code{out} for a fade-out effect. Default is @code{in}.
2631 @item start_frame, s
2632 Specify the number of the start frame for starting to apply the fade
2633 effect. Default is 0.
2636 Specify the number of frames for which the fade effect has to last. At
2637 the end of the fade-in effect the output video will have the same
2638 intensity as the input video, at the end of the fade-out transition
2639 the output video will be completely black. Default is 25.
2642 If set to 1, fade only alpha channel, if one exists on the input.
2646 @subsection Examples
2649 Fade in first 30 frames of video:
2654 The command above is equivalent to:
2660 Fade out last 45 frames of a 200-frame video:
2666 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
2668 fade=in:0:25, fade=out:975:25
2672 Make first 5 frames black, then fade in from frame 5-24:
2678 Fade in alpha over first 25 frames of video:
2680 fade=in:0:25:alpha=1
2686 Extract a single field from an interlaced image using stride
2687 arithmetic to avoid wasting CPU time. The output frames are marked as
2690 This filter accepts the following named options:
2693 Specify whether to extract the top (if the value is @code{0} or
2694 @code{top}) or the bottom field (if the value is @code{1} or
2698 If the option key is not specified, the first value sets the @var{type}
2699 option. For example:
2711 Transform the field order of the input video.
2713 It accepts one parameter which specifies the required field order that
2714 the input interlaced video will be transformed to. The parameter can
2715 assume one of the following values:
2719 output bottom field first
2721 output top field first
2724 Default value is "tff".
2726 Transformation is achieved by shifting the picture content up or down
2727 by one line, and filling the remaining line with appropriate picture content.
2728 This method is consistent with most broadcast field order converters.
2730 If the input video is not flagged as being interlaced, or it is already
2731 flagged as being of the required output field order then this filter does
2732 not alter the incoming video.
2734 This filter is very useful when converting to or from PAL DV material,
2735 which is bottom field first.
2739 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
2744 Buffer input images and send them when they are requested.
2746 This filter is mainly useful when auto-inserted by the libavfilter
2749 The filter does not take parameters.
2753 Convert the input video to one of the specified pixel formats.
2754 Libavfilter will try to pick one that is supported for the input to
2757 The filter accepts a list of pixel format names, separated by ":",
2758 for example "yuv420p:monow:rgb24".
2760 Some examples follow:
2762 # convert the input video to the format "yuv420p"
2765 # convert the input video to any of the formats in the list
2766 format=yuv420p:yuv444p:yuv410p
2771 Convert the video to specified constant framerate by duplicating or dropping
2772 frames as necessary.
2774 This filter accepts the following named parameters:
2778 Desired output framerate. The default is @code{25}.
2783 Possible values are:
2786 zero round towards 0
2790 round towards -infinity
2792 round towards +infinity
2796 The default is @code{near}.
2800 Alternatively, the options can be specified as a flat string:
2801 @var{fps}[:@var{round}].
2803 See also the @ref{setpts} filter.
2807 Select one frame every N.
2809 This filter accepts in input a string representing a positive
2810 integer. Default argument is @code{1}.
2815 Apply a frei0r effect to the input video.
2817 To enable compilation of this filter you need to install the frei0r
2818 header and configure FFmpeg with @code{--enable-frei0r}.
2820 The filter supports the syntax:
2822 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
2825 @var{filter_name} is the name of the frei0r effect to load. If the
2826 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
2827 is searched in each one of the directories specified by the colon (or
2828 semicolon on Windows platforms) separated list in @env{FREIOR_PATH},
2829 otherwise in the standard frei0r paths, which are in this order:
2830 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
2831 @file{/usr/lib/frei0r-1/}.
2833 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
2834 for the frei0r effect.
2836 A frei0r effect parameter can be a boolean (whose values are specified
2837 with "y" and "n"), a double, a color (specified by the syntax
2838 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
2839 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
2840 description), a position (specified by the syntax @var{X}/@var{Y},
2841 @var{X} and @var{Y} being float numbers) and a string.
2843 The number and kind of parameters depend on the loaded effect. If an
2844 effect parameter is not specified the default value is set.
2846 Some examples follow:
2850 Apply the distort0r effect, set the first two double parameters:
2852 frei0r=distort0r:0.5:0.01
2856 Apply the colordistance effect, take a color as first parameter:
2858 frei0r=colordistance:0.2/0.3/0.4
2859 frei0r=colordistance:violet
2860 frei0r=colordistance:0x112233
2864 Apply the perspective effect, specify the top left and top right image
2867 frei0r=perspective:0.2/0.2:0.8/0.2
2871 For more information see:
2872 @url{http://frei0r.dyne.org}
2876 The filter takes one, two or three equations as parameter, separated by ':'.
2877 The first equation is mandatory and applies to the luma plane. The two
2878 following are respectively for chroma blue and chroma red planes.
2880 The filter syntax allows named parameters:
2884 the luminance expression
2886 the chrominance blue expression
2888 the chrominance red expression
2891 If one of the chrominance expression is not defined, it falls back on the other
2892 one. If none of them are specified, they will evaluate the luminance
2895 The expressions can use the following variables and functions:
2899 The sequential number of the filtered frame, starting from @code{0}.
2902 The coordinates of the current sample.
2905 The width and height of the image.
2908 Width and height scale depending on the currently filtered plane. It is the
2909 ratio between the corresponding luma plane number of pixels and the current
2910 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2911 @code{0.5,0.5} for chroma planes.
2914 Time of the current frame, expressed in seconds.
2917 Return the value of the pixel at location (@var{x},@var{y}) of the current
2921 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
2925 Return the value of the pixel at location (@var{x},@var{y}) of the
2926 blue-difference chroma plane.
2929 Return the value of the pixel at location (@var{x},@var{y}) of the
2930 red-difference chroma plane.
2933 For functions, if @var{x} and @var{y} are outside the area, the value will be
2934 automatically clipped to the closer edge.
2936 Some examples follow:
2940 Flip the image horizontally:
2946 Generate a bidimensional sine wave, with angle @code{PI/3} and a
2947 wavelength of 100 pixels:
2949 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
2953 Generate a fancy enigmatic moving light:
2955 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
2961 Fix the banding artifacts that are sometimes introduced into nearly flat
2962 regions by truncation to 8bit color depth.
2963 Interpolate the gradients that should go where the bands are, and
2966 This filter is designed for playback only. Do not use it prior to
2967 lossy compression, because compression tends to lose the dither and
2968 bring back the bands.
2970 The filter accepts a list of options in the form of @var{key}=@var{value} pairs
2971 separated by ":". A description of the accepted options follows.
2976 The maximum amount by which the filter will change
2977 any one pixel. Also the threshold for detecting nearly flat
2978 regions. Acceptable values range from @code{0.51} to @code{64}, default value
2982 The neighborhood to fit the gradient to. A larger
2983 radius makes for smoother gradients, but also prevents the filter from
2984 modifying the pixels near detailed regions. Acceptable values are
2985 @code{8-32}, default value is @code{16}.
2989 Alternatively, the options can be specified as a flat string:
2990 @var{strength}[:@var{radius}]
2992 @subsection Examples
2996 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3002 Specify radius, omitting the strength (which will fall-back to the default
3012 Flip the input video horizontally.
3014 For example to horizontally flip the input video with @command{ffmpeg}:
3016 ffmpeg -i in.avi -vf "hflip" out.avi
3020 This filter applies a global color histogram equalization on a
3023 It can be used to correct video that has a compressed range of pixel
3024 intensities. The filter redistributes the pixel intensities to
3025 equalize their distribution across the intensity range. It may be
3026 viewed as an "automatically adjusting contrast filter". This filter is
3027 useful only for correcting degraded or poorly captured source
3030 The filter accepts parameters as a list of @var{key}=@var{value}
3031 pairs, separated by ":". If the key of the first options is omitted,
3032 the arguments are interpreted according to syntax
3033 @var{strength}:@var{intensity}:@var{antibanding}.
3035 This filter accepts the following named options:
3039 Determine the amount of equalization to be applied. As the strength
3040 is reduced, the distribution of pixel intensities more-and-more
3041 approaches that of the input frame. The value must be a float number
3042 in the range [0,1] and defaults to 0.200.
3045 Set the maximum intensity that can generated and scale the output
3046 values appropriately. The strength should be set as desired and then
3047 the intensity can be limited if needed to avoid washing-out. The value
3048 must be a float number in the range [0,1] and defaults to 0.210.
3051 Set the antibanding level. If enabled the filter will randomly vary
3052 the luminance of output pixels by a small amount to avoid banding of
3053 the histogram. Possible values are @code{none}, @code{weak} or
3054 @code{strong}. It defaults to @code{none}.
3059 High precision/quality 3d denoise filter. This filter aims to reduce
3060 image noise producing smooth images and making still images really
3061 still. It should enhance compressibility.
3063 It accepts the following optional parameters:
3064 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
3068 a non-negative float number which specifies spatial luma strength,
3071 @item chroma_spatial
3072 a non-negative float number which specifies spatial chroma strength,
3073 defaults to 3.0*@var{luma_spatial}/4.0
3076 a float number which specifies luma temporal strength, defaults to
3077 6.0*@var{luma_spatial}/4.0
3080 a float number which specifies chroma temporal strength, defaults to
3081 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3086 Modify the hue and/or the saturation of the input.
3088 This filter accepts the following optional named options:
3092 Specify the hue angle as a number of degrees. It accepts a float
3093 number or an expression, and defaults to 0.0.
3096 Specify the hue angle as a number of degrees. It accepts a float
3097 number or an expression, and defaults to 0.0.
3100 Specify the saturation in the [-10,10] range. It accepts a float number and
3104 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3105 following constants:
3109 frame count of the input frame starting from 0
3112 presentation timestamp of the input frame expressed in time base units
3115 frame rate of the input video, NAN if the input frame rate is unknown
3118 timestamp expressed in seconds, NAN if the input timestamp is unknown
3121 time base of the input video
3124 The options can also be set using the syntax: @var{hue}:@var{saturation}
3126 In this case @var{hue} is expressed in degrees.
3128 Some examples follow:
3131 Set the hue to 90 degrees and the saturation to 1.0:
3137 Same command but expressing the hue in radians:
3143 Same command without named options, hue must be expressed in degrees:
3149 Note that "h:s" syntax does not support expressions for the values of
3150 h and s, so the following example will issue an error:
3156 Rotate hue and make the saturation swing between 0
3157 and 2 over a period of 1 second:
3159 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3163 Apply a 3 seconds saturation fade-in effect starting at 0:
3168 The general fade-in expression can be written as:
3170 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3174 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3176 hue="s=max(0\, min(1\, (8-t)/3))"
3179 The general fade-out expression can be written as:
3181 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3186 @subsection Commands
3188 This filter supports the following command:
3191 Modify the hue and/or the saturation of the input video.
3192 The command accepts the same named options and syntax than when calling the
3193 filter from the command-line.
3195 If a parameter is omitted, it is kept at its current value.
3200 Interlaceing detect filter. This filter tries to detect if the input is
3201 interlaced or progressive. Top or bottom field first.
3205 Deinterlace input video by applying Donald Graft's adaptive kernel
3206 deinterling. Work on interlaced parts of a video to produce
3209 This filter accepts parameters as a list of @var{key}=@var{value}
3210 pairs, separated by ":". If the key of the first options is omitted,
3211 the arguments are interpreted according to the following syntax:
3212 @var{thresh}:@var{map}:@var{order}:@var{sharp}:@var{twoway}.
3214 The description of the accepted parameters follows.
3218 Set the threshold which affects the filter's tolerance when
3219 determining if a pixel line must be processed. It must be an integer
3220 in the range [0,255] and defaults to 10. A value of 0 will result in
3221 applying the process on every pixels.
3224 Paint pixels exceeding the threshold value to white if set to 1.
3228 Set the fields order. Swap fields if set to 1, leave fields alone if
3232 Enable additional sharpening if set to 1. Default is 0.
3235 Enable twoway sharpening if set to 1. Default is 0.
3238 @subsection Examples
3242 Apply default values:
3244 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3248 Enable additional sharpening:
3254 Paint processed pixels in white:
3260 @section lut, lutrgb, lutyuv
3262 Compute a look-up table for binding each pixel component input value
3263 to an output value, and apply it to input video.
3265 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3266 to an RGB input video.
3268 These filters accept in input a ":"-separated list of options, which
3269 specify the expressions used for computing the lookup table for the
3270 corresponding pixel component values.
3272 The @var{lut} filter requires either YUV or RGB pixel formats in
3273 input, and accepts the options:
3276 set first pixel component expression
3278 set second pixel component expression
3280 set third pixel component expression
3282 set fourth pixel component expression, corresponds to the alpha component
3285 The exact component associated to each option depends on the format in
3288 The @var{lutrgb} filter requires RGB pixel formats in input, and
3289 accepts the options:
3292 set red component expression
3294 set green component expression
3296 set blue component expression
3298 alpha component expression
3301 The @var{lutyuv} filter requires YUV pixel formats in input, and
3302 accepts the options:
3305 set Y/luminance component expression
3307 set U/Cb component expression
3309 set V/Cr component expression
3311 set alpha component expression
3314 The expressions can contain the following constants and functions:
3318 the input width and height
3321 input value for the pixel component
3324 the input value clipped in the @var{minval}-@var{maxval} range
3327 maximum value for the pixel component
3330 minimum value for the pixel component
3333 the negated value for the pixel component value clipped in the
3334 @var{minval}-@var{maxval} range , it corresponds to the expression
3335 "maxval-clipval+minval"
3338 the computed value in @var{val} clipped in the
3339 @var{minval}-@var{maxval} range
3341 @item gammaval(gamma)
3342 the computed gamma correction value of the pixel component value
3343 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3345 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3349 All expressions default to "val".
3351 @subsection Examples
3357 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3358 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3361 The above is the same as:
3363 lutrgb="r=negval:g=negval:b=negval"
3364 lutyuv="y=negval:u=negval:v=negval"
3374 Remove chroma components, turns the video into a graytone image:
3376 lutyuv="u=128:v=128"
3380 Apply a luma burning effect:
3386 Remove green and blue components:
3392 Set a constant alpha channel value on input:
3394 format=rgba,lutrgb=a="maxval-minval/2"
3398 Correct luminance gamma by a 0.5 factor:
3400 lutyuv=y=gammaval(0.5)
3406 Apply an MPlayer filter to the input video.
3408 This filter provides a wrapper around most of the filters of
3411 This wrapper is considered experimental. Some of the wrapped filters
3412 may not work properly and we may drop support for them, as they will
3413 be implemented natively into FFmpeg. Thus you should avoid
3414 depending on them when writing portable scripts.
3416 The filters accepts the parameters:
3417 @var{filter_name}[:=]@var{filter_params}
3419 @var{filter_name} is the name of a supported MPlayer filter,
3420 @var{filter_params} is a string containing the parameters accepted by
3423 The list of the currently supported filters follows:
3457 The parameter syntax and behavior for the listed filters are the same
3458 of the corresponding MPlayer filters. For detailed instructions check
3459 the "VIDEO FILTERS" section in the MPlayer manual.
3461 Some examples follow:
3464 Adjust gamma, brightness, contrast:
3470 Add temporal noise to input video:
3476 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
3482 This filter accepts an integer in input, if non-zero it negates the
3483 alpha component (if available). The default value in input is 0.
3487 Force libavfilter not to use any of the specified pixel formats for the
3488 input to the next filter.
3490 The filter accepts a list of pixel format names, separated by ":",
3491 for example "yuv420p:monow:rgb24".
3493 Some examples follow:
3495 # force libavfilter to use a format different from "yuv420p" for the
3496 # input to the vflip filter
3497 noformat=yuv420p,vflip
3499 # convert the input video to any of the formats not contained in the list
3500 noformat=yuv420p:yuv444p:yuv410p
3505 Pass the video source unchanged to the output.
3509 Apply video transform using libopencv.
3511 To enable this filter install libopencv library and headers and
3512 configure FFmpeg with @code{--enable-libopencv}.
3514 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
3516 @var{filter_name} is the name of the libopencv filter to apply.
3518 @var{filter_params} specifies the parameters to pass to the libopencv
3519 filter. If not specified the default values are assumed.
3521 Refer to the official libopencv documentation for more precise
3523 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
3525 Follows the list of supported libopencv filters.
3530 Dilate an image by using a specific structuring element.
3531 This filter corresponds to the libopencv function @code{cvDilate}.
3533 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
3535 @var{struct_el} represents a structuring element, and has the syntax:
3536 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
3538 @var{cols} and @var{rows} represent the number of columns and rows of
3539 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
3540 point, and @var{shape} the shape for the structuring element, and
3541 can be one of the values "rect", "cross", "ellipse", "custom".
3543 If the value for @var{shape} is "custom", it must be followed by a
3544 string of the form "=@var{filename}". The file with name
3545 @var{filename} is assumed to represent a binary image, with each
3546 printable character corresponding to a bright pixel. When a custom
3547 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
3548 or columns and rows of the read file are assumed instead.
3550 The default value for @var{struct_el} is "3x3+0x0/rect".
3552 @var{nb_iterations} specifies the number of times the transform is
3553 applied to the image, and defaults to 1.
3555 Follow some example:
3557 # use the default values
3560 # dilate using a structuring element with a 5x5 cross, iterate two times
3561 ocv=dilate=5x5+2x2/cross:2
3563 # read the shape from the file diamond.shape, iterate two times
3564 # the file diamond.shape may contain a pattern of characters like this:
3570 # the specified cols and rows are ignored (but not the anchor point coordinates)
3571 ocv=0x0+2x2/custom=diamond.shape:2
3576 Erode an image by using a specific structuring element.
3577 This filter corresponds to the libopencv function @code{cvErode}.
3579 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
3580 with the same syntax and semantics as the @ref{dilate} filter.
3584 Smooth the input video.
3586 The filter takes the following parameters:
3587 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
3589 @var{type} is the type of smooth filter to apply, and can be one of
3590 the following values: "blur", "blur_no_scale", "median", "gaussian",
3591 "bilateral". The default value is "gaussian".
3593 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
3594 parameters whose meanings depend on smooth type. @var{param1} and
3595 @var{param2} accept integer positive values or 0, @var{param3} and
3596 @var{param4} accept float values.
3598 The default value for @var{param1} is 3, the default value for the
3599 other parameters is 0.
3601 These parameters correspond to the parameters assigned to the
3602 libopencv function @code{cvSmooth}.
3607 Overlay one video on top of another.
3609 It takes two inputs and one output, the first input is the "main"
3610 video on which the second input is overlayed.
3612 This filter accepts a list of @var{key}=@var{value} pairs as argument,
3613 separated by ":". If the key of the first options is omitted, the
3614 arguments are interpreted according to the syntax @var{x}:@var{y}.
3616 A description of the accepted options follows.
3620 Set the expression for the x and y coordinates of the overlayed video
3621 on the main video. Default value is 0.
3623 The @var{x} and @var{y} expressions can contain the following
3626 @item main_w, main_h
3627 main input width and height
3630 same as @var{main_w} and @var{main_h}
3632 @item overlay_w, overlay_h
3633 overlay input width and height
3636 same as @var{overlay_w} and @var{overlay_h}
3640 If set to 1, force the filter to accept inputs in the RGB
3641 color space. Default value is 0.
3644 Be aware that frames are taken from each input video in timestamp
3645 order, hence, if their initial timestamps differ, it is a a good idea
3646 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
3647 have them begin in the same zero timestamp, as it does the example for
3648 the @var{movie} filter.
3650 You can chain together more overlays but you should test the
3651 efficiency of such approach.
3653 @subsection Examples
3657 Draw the overlay at 10 pixels from the bottom right corner of the main
3660 overlay=main_w-overlay_w-10:main_h-overlay_h-10
3663 Using named options the example above becomes:
3665 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
3669 Insert a transparent PNG logo in the bottom left corner of the input,
3670 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
3672 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
3676 Insert 2 different transparent PNG logos (second logo on bottom
3677 right corner) using the @command{ffmpeg} tool:
3679 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
3683 Add a transparent color layer on top of the main video, WxH specifies
3684 the size of the main input to the overlay filter:
3686 color=red@@.3:WxH [over]; [in][over] overlay [out]
3690 Play an original video and a filtered version (here with the deshake
3691 filter) side by side using the @command{ffplay} tool:
3693 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
3696 The above command is the same as:
3698 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
3702 Chain several overlays in cascade:
3704 nullsrc=s=200x200 [bg];
3705 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
3706 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
3707 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
3708 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
3709 [in3] null, [mid2] overlay=100:100 [out0]
3716 Add paddings to the input image, and places the original input at the
3717 given coordinates @var{x}, @var{y}.
3719 It accepts the following parameters:
3720 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
3722 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
3723 expressions containing the following constants:
3727 the input video width and height
3730 same as @var{in_w} and @var{in_h}
3733 the output width and height, that is the size of the padded area as
3734 specified by the @var{width} and @var{height} expressions
3737 same as @var{out_w} and @var{out_h}
3740 x and y offsets as specified by the @var{x} and @var{y}
3741 expressions, or NAN if not yet specified
3744 same as @var{iw} / @var{ih}
3747 input sample aspect ratio
3750 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3753 horizontal and vertical chroma subsample values. For example for the
3754 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3757 Follows the description of the accepted parameters.
3762 Specify the size of the output image with the paddings added. If the
3763 value for @var{width} or @var{height} is 0, the corresponding input size
3764 is used for the output.
3766 The @var{width} expression can reference the value set by the
3767 @var{height} expression, and vice versa.
3769 The default value of @var{width} and @var{height} is 0.
3773 Specify the offsets where to place the input image in the padded area
3774 with respect to the top/left border of the output image.
3776 The @var{x} expression can reference the value set by the @var{y}
3777 expression, and vice versa.
3779 The default value of @var{x} and @var{y} is 0.
3783 Specify the color of the padded area, it can be the name of a color
3784 (case insensitive match) or a 0xRRGGBB[AA] sequence.
3786 The default value of @var{color} is "black".
3790 @subsection Examples
3794 Add paddings with color "violet" to the input video. Output video
3795 size is 640x480, the top-left corner of the input video is placed at
3798 pad=640:480:0:40:violet
3802 Pad the input to get an output with dimensions increased by 3/2,
3803 and put the input video at the center of the padded area:
3805 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
3809 Pad the input to get a squared output with size equal to the maximum
3810 value between the input width and height, and put the input video at
3811 the center of the padded area:
3813 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
3817 Pad the input to get a final w/h ratio of 16:9:
3819 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
3823 In case of anamorphic video, in order to set the output display aspect
3824 correctly, it is necessary to use @var{sar} in the expression,
3825 according to the relation:
3827 (ih * X / ih) * sar = output_dar
3828 X = output_dar / sar
3831 Thus the previous example needs to be modified to:
3833 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
3837 Double output size and put the input video in the bottom-right
3838 corner of the output padded area:
3840 pad="2*iw:2*ih:ow-iw:oh-ih"
3844 @section pixdesctest
3846 Pixel format descriptor test filter, mainly useful for internal
3847 testing. The output video should be equal to the input video.
3851 format=monow, pixdesctest
3854 can be used to test the monowhite pixel format descriptor definition.
3858 Enable the specified chain of postprocessing subfilters using libpostproc. This
3859 library should be automatically selected with a GPL build (@code{--enable-gpl}).
3860 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
3861 Each subfilter and some options have a short and a long name that can be used
3862 interchangeably, i.e. dr/dering are the same.
3864 All subfilters share common options to determine their scope:
3868 Honor the quality commands for this subfilter.
3871 Do chrominance filtering, too (default).
3874 Do luminance filtering only (no chrominance).
3877 Do chrominance filtering only (no luminance).
3880 These options can be appended after the subfilter name, separated by a ':'.
3882 Available subfilters are:
3885 @item hb/hdeblock[:difference[:flatness]]
3886 Horizontal deblocking filter
3889 Difference factor where higher values mean more deblocking (default: @code{32}).
3891 Flatness threshold where lower values mean more deblocking (default: @code{39}).
3894 @item vb/vdeblock[:difference[:flatness]]
3895 Vertical deblocking filter
3898 Difference factor where higher values mean more deblocking (default: @code{32}).
3900 Flatness threshold where lower values mean more deblocking (default: @code{39}).
3903 @item ha/hadeblock[:difference[:flatness]]
3904 Accurate horizontal deblocking filter
3907 Difference factor where higher values mean more deblocking (default: @code{32}).
3909 Flatness threshold where lower values mean more deblocking (default: @code{39}).
3912 @item va/vadeblock[:difference[:flatness]]
3913 Accurate vertical deblocking filter
3916 Difference factor where higher values mean more deblocking (default: @code{32}).
3918 Flatness threshold where lower values mean more deblocking (default: @code{39}).
3922 The horizontal and vertical deblocking filters share the difference and
3923 flatness values so you cannot set different horizontal and vertical
3928 Experimental horizontal deblocking filter
3931 Experimental vertical deblocking filter
3936 @item tn/tmpnoise[:threshold1[:threshold2[:threshold3]]], temporal noise reducer
3939 larger -> stronger filtering
3941 larger -> stronger filtering
3943 larger -> stronger filtering
3946 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
3949 Stretch luminance to @code{0-255}.
3952 @item lb/linblenddeint
3953 Linear blend deinterlacing filter that deinterlaces the given block by
3954 filtering all lines with a @code{(1 2 1)} filter.
3956 @item li/linipoldeint
3957 Linear interpolating deinterlacing filter that deinterlaces the given block by
3958 linearly interpolating every second line.
3960 @item ci/cubicipoldeint
3961 Cubic interpolating deinterlacing filter deinterlaces the given block by
3962 cubically interpolating every second line.
3964 @item md/mediandeint
3965 Median deinterlacing filter that deinterlaces the given block by applying a
3966 median filter to every second line.
3968 @item fd/ffmpegdeint
3969 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
3970 second line with a @code{(-1 4 2 4 -1)} filter.
3973 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
3974 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
3976 @item fq/forceQuant[:quantizer]
3977 Overrides the quantizer table from the input with the constant quantizer you
3985 Default pp filter combination (@code{hb:a,vb:a,dr:a})
3988 Fast pp filter combination (@code{h1:a,v1:a,dr:a})
3991 High quality pp filter combination (@code{ha:a:128:7,va:a,dr:a})
3994 @subsection Examples
3998 Apply horizontal and vertical deblocking, deringing and automatic
3999 brightness/contrast:
4005 Apply default filters without brightness/contrast correction:
4011 Apply default filters and temporal denoiser:
4013 pp=default/tmpnoise:1:2:3
4017 Apply deblocking on luminance only, and switch vertical deblocking on or off
4018 automatically depending on available CPU time:
4026 Suppress a TV station logo, using an image file to determine which
4027 pixels comprise the logo. It works by filling in the pixels that
4028 comprise the logo with neighboring pixels.
4030 This filter requires one argument which specifies the filter bitmap
4031 file, which can be any image format supported by libavformat. The
4032 width and height of the image file must match those of the video
4033 stream being processed.
4035 Pixels in the provided bitmap image with a value of zero are not
4036 considered part of the logo, non-zero pixels are considered part of
4037 the logo. If you use white (255) for the logo and black (0) for the
4038 rest, you will be safe. For making the filter bitmap, it is
4039 recommended to take a screen capture of a black frame with the logo
4040 visible, and then using a threshold filter followed by the erode
4041 filter once or twice.
4043 If needed, little splotches can be fixed manually. Remember that if
4044 logo pixels are not covered, the filter quality will be much
4045 reduced. Marking too many pixels as part of the logo does not hurt as
4046 much, but it will increase the amount of blurring needed to cover over
4047 the image and will destroy more information than necessary, and extra
4048 pixels will slow things down on a large logo.
4052 Scale (resize) the input video, using the libswscale library.
4054 The scale filter forces the output display aspect ratio to be the same
4055 of the input, by changing the output sample aspect ratio.
4057 This filter accepts a list of named options in the form of
4058 @var{key}=@var{value} pairs separated by ":". If the key for the first
4059 two options is not specified, the assumed keys for the first two
4060 values are @code{w} and @code{h}. If the first option has no key and
4061 can be interpreted like a video size specification, it will be used
4062 to set the video size.
4064 A description of the accepted options follows.
4068 Set the video width expression, default value is @code{iw}. See below
4069 for the list of accepted constants.
4072 Set the video heiht expression, default value is @code{ih}.
4073 See below for the list of accepted constants.
4076 Set the interlacing. It accepts the following values:
4080 force interlaced aware scaling
4083 do not apply interlaced scaling
4086 select interlaced aware scaling depending on whether the source frames
4087 are flagged as interlaced or not
4090 Default value is @code{0}.
4093 Set libswscale scaling flags. If not explictly specified the filter
4094 applies a bilinear scaling algorithm.
4097 Set the video size, the value must be a valid abbreviation or in the
4098 form @var{width}x@var{height}.
4101 The values of the @var{w} and @var{h} options are expressions
4102 containing the following constants:
4106 the input width and height
4109 same as @var{in_w} and @var{in_h}
4112 the output (cropped) width and height
4115 same as @var{out_w} and @var{out_h}
4118 same as @var{iw} / @var{ih}
4121 input sample aspect ratio
4124 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4127 horizontal and vertical chroma subsample values. For example for the
4128 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4131 If the input image format is different from the format requested by
4132 the next filter, the scale filter will convert the input to the
4135 If the value for @var{width} or @var{height} is 0, the respective input
4136 size is used for the output.
4138 If the value for @var{width} or @var{height} is -1, the scale filter will
4139 use, for the respective output size, a value that maintains the aspect
4140 ratio of the input image.
4142 @subsection Examples
4146 Scale the input video to a size of 200x100:
4151 This is equivalent to:
4162 Specify a size abbreviation for the output size:
4167 which can also be written as:
4173 Scale the input to 2x:
4179 The above is the same as:
4185 Scale the input to 2x with forced interlaced scaling:
4187 scale=2*iw:2*ih:interl=1
4191 Scale the input to half size:
4197 Increase the width, and set the height to the same size:
4203 Seek for Greek harmony:
4210 Increase the height, and set the width to 3/2 of the height:
4216 Increase the size, but make the size a multiple of the chroma:
4218 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4222 Increase the width to a maximum of 500 pixels, keep the same input
4225 scale='min(500\, iw*3/2):-1'
4229 @section setdar, setsar
4231 The @code{setdar} filter sets the Display Aspect Ratio for the filter
4234 This is done by changing the specified Sample (aka Pixel) Aspect
4235 Ratio, according to the following equation:
4237 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
4240 Keep in mind that the @code{setdar} filter does not modify the pixel
4241 dimensions of the video frame. Also the display aspect ratio set by
4242 this filter may be changed by later filters in the filterchain,
4243 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
4246 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
4247 the filter output video.
4249 Note that as a consequence of the application of this filter, the
4250 output display aspect ratio will change according to the equation
4253 Keep in mind that the sample aspect ratio set by the @code{setsar}
4254 filter may be changed by later filters in the filterchain, e.g. if
4255 another "setsar" or a "setdar" filter is applied.
4257 The @code{setdar} and @code{setsar} filters accept a string in the
4258 form @var{num}:@var{den} expressing an aspect ratio, or the following
4259 named options, expressed as a sequence of @var{key}=@var{value} pairs,
4264 Set the maximum integer value to use for expressing numerator and
4265 denominator when reducing the expressed aspect ratio to a rational.
4266 Default value is @code{100}.
4269 Set the aspect ratio used by the filter.
4271 The parameter can be a floating point number string, an expression, or
4272 a string of the form @var{num}:@var{den}, where @var{num} and
4273 @var{den} are the numerator and denominator of the aspect ratio. If
4274 the parameter is not specified, it is assumed the value "0".
4275 In case the form "@var{num}:@var{den}" the @code{:} character should
4279 If the keys are omitted in the named options list, the specifed values
4280 are assumed to be @var{ratio} and @var{max} in that order.
4282 For example to change the display aspect ratio to 16:9, specify:
4287 The example above is equivalent to:
4292 To change the sample aspect ratio to 10:11, specify:
4297 To set a display aspect ratio of 16:9, and specify a maximum integer value of
4298 1000 in the aspect ratio reduction, use the command:
4300 setdar=ratio='16:9':max=1000
4305 Force field for the output video frame.
4307 The @code{setfield} filter marks the interlace type field for the
4308 output frames. It does not change the input frame, but only sets the
4309 corresponding property, which affects how the frame is treated by
4310 following filters (e.g. @code{fieldorder} or @code{yadif}).
4312 This filter accepts a single option @option{mode}, which can be
4313 specified either by setting @code{mode=VALUE} or setting the value
4314 alone. Available values are:
4318 Keep the same field property.
4321 Mark the frame as bottom-field-first.
4324 Mark the frame as top-field-first.
4327 Mark the frame as progressive.
4332 Show a line containing various information for each input video frame.
4333 The input video is not modified.
4335 The shown line contains a sequence of key/value pairs of the form
4336 @var{key}:@var{value}.
4338 A description of each shown parameter follows:
4342 sequential number of the input frame, starting from 0
4345 Presentation TimeStamp of the input frame, expressed as a number of
4346 time base units. The time base unit depends on the filter input pad.
4349 Presentation TimeStamp of the input frame, expressed as a number of
4353 position of the frame in the input stream, -1 if this information in
4354 unavailable and/or meaningless (for example in case of synthetic video)
4360 sample aspect ratio of the input frame, expressed in the form
4364 size of the input frame, expressed in the form
4365 @var{width}x@var{height}
4368 interlaced mode ("P" for "progressive", "T" for top field first, "B"
4369 for bottom field first)
4372 1 if the frame is a key frame, 0 otherwise
4375 picture type of the input frame ("I" for an I-frame, "P" for a
4376 P-frame, "B" for a B-frame, "?" for unknown type).
4377 Check also the documentation of the @code{AVPictureType} enum and of
4378 the @code{av_get_picture_type_char} function defined in
4379 @file{libavutil/avutil.h}.
4382 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
4384 @item plane_checksum
4385 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
4386 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
4391 Blur the input video without impacting the outlines.
4393 The filter accepts the following parameters:
4394 @var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
4396 Parameters prefixed by @var{luma} indicate that they work on the
4397 luminance of the pixels whereas parameters prefixed by @var{chroma}
4398 refer to the chrominance of the pixels.
4400 If the chroma parameters are not set, the luma parameters are used for
4401 either the luminance and the chrominance of the pixels.
4403 @var{luma_radius} or @var{chroma_radius} must be a float number in the
4404 range [0.1,5.0] that specifies the variance of the gaussian filter
4405 used to blur the image (slower if larger).
4407 @var{luma_strength} or @var{chroma_strength} must be a float number in
4408 the range [-1.0,1.0] that configures the blurring. A value included in
4409 [0.0,1.0] will blur the image whereas a value included in [-1.0,0.0]
4410 will sharpen the image.
4412 @var{luma_threshold} or @var{chroma_threshold} must be an integer in
4413 the range [-30,30] that is used as a coefficient to determine whether
4414 a pixel should be blurred or not. A value of 0 will filter all the
4415 image, a value included in [0,30] will filter flat areas and a value
4416 included in [-30,0] will filter edges.
4421 Draw subtitles on top of input video using the libass library.
4423 To enable compilation of this filter you need to configure FFmpeg with
4424 @code{--enable-libass}. This filter also requires a build with libavcodec and
4425 libavformat to convert the passed subtitles file to ASS (Advanced Substation
4426 Alpha) subtitles format.
4428 This filter accepts the following named options, expressed as a
4429 sequence of @var{key}=@var{value} pairs, separated by ":".
4433 Set the filename of the subtitle file to read. It must be specified.
4436 Specify the size of the original video, the video for which the ASS file
4437 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
4438 necessary to correctly scale the fonts if the aspect ratio has been changed.
4441 If the first key is not specified, it is assumed that the first value
4442 specifies the @option{filename}.
4444 For example, to render the file @file{sub.srt} on top of the input
4445 video, use the command:
4450 which is equivalent to:
4452 subtitles=filename=sub.srt
4457 Split input video into several identical outputs.
4459 The filter accepts a single parameter which specifies the number of outputs. If
4460 unspecified, it defaults to 2.
4464 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
4466 will create 5 copies of the input video.
4470 [in] split [splitout1][splitout2];
4471 [splitout1] crop=100:100:0:0 [cropout];
4472 [splitout2] pad=200:200:100:100 [padout];
4475 will create two separate outputs from the same input, one cropped and
4480 Scale the input by 2x and smooth using the Super2xSaI (Scale and
4481 Interpolate) pixel art scaling algorithm.
4483 Useful for enlarging pixel art images without reducing sharpness.
4489 Select the most representative frame in a given sequence of consecutive frames.
4491 It accepts as argument the frames batch size to analyze (default @var{N}=100);
4492 in a set of @var{N} frames, the filter will pick one of them, and then handle
4493 the next batch of @var{N} frames until the end.
4495 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
4496 value will result in a higher memory usage, so a high value is not recommended.
4498 The following example extract one picture each 50 frames:
4503 Complete example of a thumbnail creation with @command{ffmpeg}:
4505 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
4510 Tile several successive frames together.
4512 It accepts a list of options in the form of @var{key}=@var{value} pairs
4513 separated by ":". A description of the accepted options follows.
4518 Set the grid size (i.e. the number of lines and columns) in the form
4522 Set the outer border margin in pixels.
4525 Set the inner border thickness (i.e. the number of pixels between frames). For
4526 more advanced padding options (such as having different values for the edges),
4527 refer to the pad video filter.
4530 Set the maximum number of frames to render in the given area. It must be less
4531 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
4532 the area will be used.
4536 Alternatively, the options can be specified as a flat string:
4538 @var{layout}[:@var{nb_frames}[:@var{margin}[:@var{padding}]]]
4540 For example, produce 8×8 PNG tiles of all keyframes (@option{-skip_frame
4543 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
4545 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
4546 duplicating each output frame to accomodate the originally detected frame
4549 Another example to display @code{5} pictures in an area of @code{3x2} frames,
4550 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
4551 mixed flat and named options:
4553 tile=3x2:nb_frames=5:padding=7:margin=2
4558 Perform various types of temporal field interlacing.
4560 Frames are counted starting from 1, so the first input frame is
4563 This filter accepts options in the form of @var{key}=@var{value} pairs
4565 Alternatively, the @var{mode} option can be specified as a value alone,
4566 optionally followed by a ":" and further ":" separated @var{key}=@var{value}
4569 A description of the accepted options follows.
4574 Specify the mode of the interlacing. This option can also be specified
4575 as a value alone. See below for a list of values for this option.
4577 Available values are:
4581 Move odd frames into the upper field, even into the lower field,
4582 generating a double height frame at half framerate.
4585 Only output even frames, odd frames are dropped, generating a frame with
4586 unchanged height at half framerate.
4589 Only output odd frames, even frames are dropped, generating a frame with
4590 unchanged height at half framerate.
4593 Expand each frame to full height, but pad alternate lines with black,
4594 generating a frame with double height at the same input framerate.
4596 @item interleave_top, 4
4597 Interleave the upper field from odd frames with the lower field from
4598 even frames, generating a frame with unchanged height at half framerate.
4600 @item interleave_bottom, 5
4601 Interleave the lower field from odd frames with the upper field from
4602 even frames, generating a frame with unchanged height at half framerate.
4604 @item interlacex2, 6
4605 Double frame rate with unchanged height. Frames are inserted each
4606 containing the second temporal field from the previous input frame and
4607 the first temporal field from the next input frame. This mode relies on
4608 the top_field_first flag. Useful for interlaced video displays with no
4609 field synchronisation.
4612 Numeric values are deprecated but are accepted for backward
4613 compatibility reasons.
4615 Default mode is @code{merge}.
4618 Specify flags influencing the filter process.
4620 Available value for @var{flags} is:
4623 @item low_pass_filter, vlfp
4624 Enable vertical low-pass filtering in the filter.
4625 Vertical low-pass filtering is required when creating an interlaced
4626 destination from a progressive source which contains high-frequency
4627 vertical detail. Filtering will reduce interlace 'twitter' and Moire
4630 Vertical low-pass filtering can only be enabled for @option{mode}
4631 @var{interleave_top} and @var{interleave_bottom}.
4638 Transpose rows with columns in the input video and optionally flip it.
4640 The filter accepts parameters as a list of @var{key}=@var{value}
4641 pairs, separated by ':'. If the key of the first options is omitted,
4642 the arguments are interpreted according to the syntax
4643 @var{dir}:@var{passthrough}.
4647 Specify the transposition direction. Can assume the following values:
4651 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
4659 Rotate by 90 degrees clockwise, that is:
4667 Rotate by 90 degrees counterclockwise, that is:
4675 Rotate by 90 degrees clockwise and vertically flip, that is:
4683 For values between 4-7, the transposition is only done if the input
4684 video geometry is portrait and not landscape. These values are
4685 deprecated, the @code{passthrough} option should be used instead.
4688 Do not apply the transposition if the input geometry matches the one
4689 specified by the specified value. It accepts the following values:
4692 Always apply transposition.
4694 Preserve portrait geometry (when @var{height} >= @var{width}).
4696 Preserve landscape geometry (when @var{width} >= @var{height}).
4699 Default value is @code{none}.
4702 For example to rotate by 90 degrees clockwise and preserve portrait
4705 transpose=dir=1:passthrough=portrait
4708 The command above can also be specified as:
4710 transpose=1:portrait
4715 Sharpen or blur the input video.
4717 It accepts the following parameters:
4718 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
4720 Negative values for the amount will blur the input video, while positive
4721 values will sharpen. All parameters are optional and default to the
4722 equivalent of the string '5:5:1.0:5:5:0.0'.
4727 Set the luma matrix horizontal size. It can be an integer between 3
4728 and 13, default value is 5.
4731 Set the luma matrix vertical size. It can be an integer between 3
4732 and 13, default value is 5.
4735 Set the luma effect strength. It can be a float number between -2.0
4736 and 5.0, default value is 1.0.
4738 @item chroma_msize_x
4739 Set the chroma matrix horizontal size. It can be an integer between 3
4740 and 13, default value is 5.
4742 @item chroma_msize_y
4743 Set the chroma matrix vertical size. It can be an integer between 3
4744 and 13, default value is 5.
4747 Set the chroma effect strength. It can be a float number between -2.0
4748 and 5.0, default value is 0.0.
4753 # Strong luma sharpen effect parameters
4756 # Strong blur of both luma and chroma parameters
4757 unsharp=7:7:-2:7:7:-2
4759 # Use the default values with @command{ffmpeg}
4760 ffmpeg -i in.avi -vf "unsharp" out.mp4
4765 Flip the input video vertically.
4768 ffmpeg -i in.avi -vf "vflip" out.avi
4773 Deinterlace the input video ("yadif" means "yet another deinterlacing
4776 The filter accepts parameters as a list of @var{key}=@var{value}
4777 pairs, separated by ":". If the key of the first options is omitted,
4778 the arguments are interpreted according to syntax
4779 @var{mode}:@var{parity}:@var{deint}.
4781 The description of the accepted parameters follows.
4785 Specify the interlacing mode to adopt. Accept one of the following
4790 output 1 frame for each frame
4792 output 1 frame for each field
4793 @item 2, send_frame_nospatial
4794 like @code{send_frame} but skip spatial interlacing check
4795 @item 3, send_field_nospatial
4796 like @code{send_field} but skip spatial interlacing check
4799 Default value is @code{send_frame}.
4802 Specify the picture field parity assumed for the input interlaced
4803 video. Accept one of the following values:
4807 assume top field first
4809 assume bottom field first
4811 enable automatic detection
4814 Default value is @code{auto}.
4815 If interlacing is unknown or decoder does not export this information,
4816 top field first will be assumed.
4819 Specify which frames to deinterlace. Accept one of the following
4824 deinterlace all frames
4826 only deinterlace frames marked as interlaced
4829 Default value is @code{all}.
4832 @c man end VIDEO FILTERS
4834 @chapter Video Sources
4835 @c man begin VIDEO SOURCES
4837 Below is a description of the currently available video sources.
4841 Buffer video frames, and make them available to the filter chain.
4843 This source is mainly intended for a programmatic use, in particular
4844 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
4846 It accepts a list of options in the form of @var{key}=@var{value} pairs
4847 separated by ":". A description of the accepted options follows.
4852 Specify the size (width and height) of the buffered video frames.
4855 A string representing the pixel format of the buffered video frames.
4856 It may be a number corresponding to a pixel format, or a pixel format
4860 Specify the timebase assumed by the timestamps of the buffered frames.
4863 Specify the frame rate expected for the video stream.
4866 Specify the sample aspect ratio assumed by the video frames.
4869 Specify the optional parameters to be used for the scale filter which
4870 is automatically inserted when an input change is detected in the
4871 input size or format.
4876 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
4879 will instruct the source to accept video frames with size 320x240 and
4880 with format "yuv410p", assuming 1/24 as the timestamps timebase and
4881 square pixels (1:1 sample aspect ratio).
4882 Since the pixel format with name "yuv410p" corresponds to the number 6
4883 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
4884 this example corresponds to:
4886 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
4889 Alternatively, the options can be specified as a flat string, but this
4890 syntax is deprecated:
4892 @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}]
4896 Create a pattern generated by an elementary cellular automaton.
4898 The initial state of the cellular automaton can be defined through the
4899 @option{filename}, and @option{pattern} options. If such options are
4900 not specified an initial state is created randomly.
4902 At each new frame a new row in the video is filled with the result of
4903 the cellular automaton next generation. The behavior when the whole
4904 frame is filled is defined by the @option{scroll} option.
4906 This source accepts a list of options in the form of
4907 @var{key}=@var{value} pairs separated by ":". A description of the
4908 accepted options follows.
4912 Read the initial cellular automaton state, i.e. the starting row, from
4914 In the file, each non-whitespace character is considered an alive
4915 cell, a newline will terminate the row, and further characters in the
4916 file will be ignored.
4919 Read the initial cellular automaton state, i.e. the starting row, from
4920 the specified string.
4922 Each non-whitespace character in the string is considered an alive
4923 cell, a newline will terminate the row, and further characters in the
4924 string will be ignored.
4927 Set the video rate, that is the number of frames generated per second.
4930 @item random_fill_ratio, ratio
4931 Set the random fill ratio for the initial cellular automaton row. It
4932 is a floating point number value ranging from 0 to 1, defaults to
4935 This option is ignored when a file or a pattern is specified.
4937 @item random_seed, seed
4938 Set the seed for filling randomly the initial row, must be an integer
4939 included between 0 and UINT32_MAX. If not specified, or if explicitly
4940 set to -1, the filter will try to use a good random seed on a best
4944 Set the cellular automaton rule, it is a number ranging from 0 to 255.
4945 Default value is 110.
4948 Set the size of the output video.
4950 If @option{filename} or @option{pattern} is specified, the size is set
4951 by default to the width of the specified initial state row, and the
4952 height is set to @var{width} * PHI.
4954 If @option{size} is set, it must contain the width of the specified
4955 pattern string, and the specified pattern will be centered in the
4958 If a filename or a pattern string is not specified, the size value
4959 defaults to "320x518" (used for a randomly generated initial state).
4962 If set to 1, scroll the output upward when all the rows in the output
4963 have been already filled. If set to 0, the new generated row will be
4964 written over the top row just after the bottom row is filled.
4967 @item start_full, full
4968 If set to 1, completely fill the output with generated rows before
4969 outputting the first frame.
4970 This is the default behavior, for disabling set the value to 0.
4973 If set to 1, stitch the left and right row edges together.
4974 This is the default behavior, for disabling set the value to 0.
4977 @subsection Examples
4981 Read the initial state from @file{pattern}, and specify an output of
4984 cellauto=f=pattern:s=200x400
4988 Generate a random initial row with a width of 200 cells, with a fill
4991 cellauto=ratio=2/3:s=200x200
4995 Create a pattern generated by rule 18 starting by a single alive cell
4996 centered on an initial row with width 100:
4998 cellauto=p=@@:s=100x400:full=0:rule=18
5002 Specify a more elaborated initial pattern:
5004 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5011 Generate a Mandelbrot set fractal, and progressively zoom towards the
5012 point specified with @var{start_x} and @var{start_y}.
5014 This source accepts a list of options in the form of
5015 @var{key}=@var{value} pairs separated by ":". A description of the
5016 accepted options follows.
5021 Set the terminal pts value. Default value is 400.
5024 Set the terminal scale value.
5025 Must be a floating point value. Default value is 0.3.
5028 Set the inner coloring mode, that is the algorithm used to draw the
5029 Mandelbrot fractal internal region.
5031 It shall assume one of the following values:
5036 Show time until convergence.
5038 Set color based on point closest to the origin of the iterations.
5043 Default value is @var{mincol}.
5046 Set the bailout value. Default value is 10.0.
5049 Set the maximum of iterations performed by the rendering
5050 algorithm. Default value is 7189.
5053 Set outer coloring mode.
5054 It shall assume one of following values:
5056 @item iteration_count
5057 Set iteration cound mode.
5058 @item normalized_iteration_count
5059 set normalized iteration count mode.
5061 Default value is @var{normalized_iteration_count}.
5064 Set frame rate, expressed as number of frames per second. Default
5068 Set frame size. Default value is "640x480".
5071 Set the initial scale value. Default value is 3.0.
5074 Set the initial x position. Must be a floating point value between
5075 -100 and 100. Default value is -0.743643887037158704752191506114774.
5078 Set the initial y position. Must be a floating point value between
5079 -100 and 100. Default value is -0.131825904205311970493132056385139.
5084 Generate various test patterns, as generated by the MPlayer test filter.
5086 The size of the generated video is fixed, and is 256x256.
5087 This source is useful in particular for testing encoding features.
5089 This source accepts an optional sequence of @var{key}=@var{value} pairs,
5090 separated by ":". The description of the accepted options follows.
5095 Specify the frame rate of the sourced video, as the number of frames
5096 generated per second. It has to be a string in the format
5097 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5098 number or a valid video frame rate abbreviation. The default value is
5102 Set the video duration of the sourced video. The accepted syntax is:
5107 See also the function @code{av_parse_time()}.
5109 If not specified, or the expressed duration is negative, the video is
5110 supposed to be generated forever.
5114 Set the number or the name of the test to perform. Supported tests are:
5129 Default value is "all", which will cycle through the list of all tests.
5132 For example the following:
5137 will generate a "dc_luma" test pattern.
5141 Provide a frei0r source.
5143 To enable compilation of this filter you need to install the frei0r
5144 header and configure FFmpeg with @code{--enable-frei0r}.
5146 The source supports the syntax:
5148 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
5151 @var{size} is the size of the video to generate, may be a string of the
5152 form @var{width}x@var{height} or a frame size abbreviation.
5153 @var{rate} is the rate of the video to generate, may be a string of
5154 the form @var{num}/@var{den} or a frame rate abbreviation.
5155 @var{src_name} is the name to the frei0r source to load. For more
5156 information regarding frei0r and how to set the parameters read the
5157 section @ref{frei0r} in the description of the video filters.
5159 For example, to generate a frei0r partik0l source with size 200x200
5160 and frame rate 10 which is overlayed on the overlay filter main input:
5162 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
5167 Generate a life pattern.
5169 This source is based on a generalization of John Conway's life game.
5171 The sourced input represents a life grid, each pixel represents a cell
5172 which can be in one of two possible states, alive or dead. Every cell
5173 interacts with its eight neighbours, which are the cells that are
5174 horizontally, vertically, or diagonally adjacent.
5176 At each interaction the grid evolves according to the adopted rule,
5177 which specifies the number of neighbor alive cells which will make a
5178 cell stay alive or born. The @option{rule} option allows to specify
5181 This source accepts a list of options in the form of
5182 @var{key}=@var{value} pairs separated by ":". A description of the
5183 accepted options follows.
5187 Set the file from which to read the initial grid state. In the file,
5188 each non-whitespace character is considered an alive cell, and newline
5189 is used to delimit the end of each row.
5191 If this option is not specified, the initial grid is generated
5195 Set the video rate, that is the number of frames generated per second.
5198 @item random_fill_ratio, ratio
5199 Set the random fill ratio for the initial random grid. It is a
5200 floating point number value ranging from 0 to 1, defaults to 1/PHI.
5201 It is ignored when a file is specified.
5203 @item random_seed, seed
5204 Set the seed for filling the initial random grid, must be an integer
5205 included between 0 and UINT32_MAX. If not specified, or if explicitly
5206 set to -1, the filter will try to use a good random seed on a best
5212 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
5213 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
5214 @var{NS} specifies the number of alive neighbor cells which make a
5215 live cell stay alive, and @var{NB} the number of alive neighbor cells
5216 which make a dead cell to become alive (i.e. to "born").
5217 "s" and "b" can be used in place of "S" and "B", respectively.
5219 Alternatively a rule can be specified by an 18-bits integer. The 9
5220 high order bits are used to encode the next cell state if it is alive
5221 for each number of neighbor alive cells, the low order bits specify
5222 the rule for "borning" new cells. Higher order bits encode for an
5223 higher number of neighbor cells.
5224 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
5225 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
5227 Default value is "S23/B3", which is the original Conway's game of life
5228 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
5229 cells, and will born a new cell if there are three alive cells around
5233 Set the size of the output video.
5235 If @option{filename} is specified, the size is set by default to the
5236 same size of the input file. If @option{size} is set, it must contain
5237 the size specified in the input file, and the initial grid defined in
5238 that file is centered in the larger resulting area.
5240 If a filename is not specified, the size value defaults to "320x240"
5241 (used for a randomly generated initial grid).
5244 If set to 1, stitch the left and right grid edges together, and the
5245 top and bottom edges also. Defaults to 1.
5248 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
5249 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
5250 value from 0 to 255.
5253 Set the color of living (or new born) cells.
5256 Set the color of dead cells. If @option{mold} is set, this is the first color
5257 used to represent a dead cell.
5260 Set mold color, for definitely dead and moldy cells.
5263 @subsection Examples
5267 Read a grid from @file{pattern}, and center it on a grid of size
5270 life=f=pattern:s=300x300
5274 Generate a random grid of size 200x200, with a fill ratio of 2/3:
5276 life=ratio=2/3:s=200x200
5280 Specify a custom rule for evolving a randomly generated grid:
5286 Full example with slow death effect (mold) using @command{ffplay}:
5288 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
5292 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
5294 The @code{color} source provides an uniformly colored input.
5296 The @code{nullsrc} source returns unprocessed video frames. It is
5297 mainly useful to be employed in analysis / debugging tools, or as the
5298 source for filters which ignore the input data.
5300 The @code{rgbtestsrc} source generates an RGB test pattern useful for
5301 detecting RGB vs BGR issues. You should see a red, green and blue
5302 stripe from top to bottom.
5304 The @code{smptebars} source generates a color bars pattern, based on
5305 the SMPTE Engineering Guideline EG 1-1990.
5307 The @code{testsrc} source generates a test video pattern, showing a
5308 color pattern, a scrolling gradient and a timestamp. This is mainly
5309 intended for testing purposes.
5311 These sources accept an optional sequence of @var{key}=@var{value} pairs,
5312 separated by ":". The description of the accepted options follows.
5317 Specify the color of the source, only used in the @code{color}
5318 source. It can be the name of a color (case insensitive match) or a
5319 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
5320 default value is "black".
5323 Specify the size of the sourced video, it may be a string of the form
5324 @var{width}x@var{height}, or the name of a size abbreviation. The
5325 default value is "320x240".
5328 Specify the frame rate of the sourced video, as the number of frames
5329 generated per second. It has to be a string in the format
5330 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5331 number or a valid video frame rate abbreviation. The default value is
5335 Set the sample aspect ratio of the sourced video.
5338 Set the video duration of the sourced video. The accepted syntax is:
5340 [-]HH[:MM[:SS[.m...]]]
5343 See also the function @code{av_parse_time()}.
5345 If not specified, or the expressed duration is negative, the video is
5346 supposed to be generated forever.
5349 Set the number of decimals to show in the timestamp, only used in the
5350 @code{testsrc} source.
5352 The displayed timestamp value will correspond to the original
5353 timestamp value multiplied by the power of 10 of the specified
5354 value. Default value is 0.
5357 For example the following:
5359 testsrc=duration=5.3:size=qcif:rate=10
5362 will generate a video with a duration of 5.3 seconds, with size
5363 176x144 and a frame rate of 10 frames per second.
5365 The following graph description will generate a red source
5366 with an opacity of 0.2, with size "qcif" and a frame rate of 10
5369 color=c=red@@0.2:s=qcif:r=10
5372 If the input content is to be ignored, @code{nullsrc} can be used. The
5373 following command generates noise in the luminance plane by employing
5374 the @code{geq} filter:
5376 nullsrc=s=256x256, geq=random(1)*255:128:128
5379 @c man end VIDEO SOURCES
5381 @chapter Video Sinks
5382 @c man begin VIDEO SINKS
5384 Below is a description of the currently available video sinks.
5388 Buffer video frames, and make them available to the end of the filter
5391 This sink is mainly intended for a programmatic use, in particular
5392 through the interface defined in @file{libavfilter/buffersink.h}.
5394 It does not require a string parameter in input, but you need to
5395 specify a pointer to a list of supported pixel formats terminated by
5396 -1 in the opaque parameter provided to @code{avfilter_init_filter}
5397 when initializing this sink.
5401 Null video sink, do absolutely nothing with the input video. It is
5402 mainly useful as a template and to be employed in analysis / debugging
5405 @c man end VIDEO SINKS
5407 @chapter Multimedia Filters
5408 @c man begin MULTIMEDIA FILTERS
5410 Below is a description of the currently available multimedia filters.
5412 @section aselect, select
5413 Select frames to pass in output.
5415 These filters accept a single option @option{expr} or @option{e}
5416 specifying the select expression, which can be specified either by
5417 specyfing @code{expr=VALUE} or specifying the expression
5420 The select expression is evaluated for each input frame. If the
5421 evaluation result is a non-zero value, the frame is selected and
5422 passed to the output, otherwise it is discarded.
5424 The expression can contain the following constants:
5428 the sequential number of the filtered frame, starting from 0
5431 the sequential number of the selected frame, starting from 0
5433 @item prev_selected_n
5434 the sequential number of the last selected frame, NAN if undefined
5437 timebase of the input timestamps
5440 the PTS (Presentation TimeStamp) of the filtered video frame,
5441 expressed in @var{TB} units, NAN if undefined
5444 the PTS (Presentation TimeStamp) of the filtered video frame,
5445 expressed in seconds, NAN if undefined
5448 the PTS of the previously filtered video frame, NAN if undefined
5450 @item prev_selected_pts
5451 the PTS of the last previously filtered video frame, NAN if undefined
5453 @item prev_selected_t
5454 the PTS of the last previously selected video frame, NAN if undefined
5457 the PTS of the first video frame in the video, NAN if undefined
5460 the time of the first video frame in the video, NAN if undefined
5462 @item pict_type @emph{(video only)}
5463 the type of the filtered frame, can assume one of the following
5475 @item interlace_type @emph{(video only)}
5476 the frame interlace type, can assume one of the following values:
5479 the frame is progressive (not interlaced)
5481 the frame is top-field-first
5483 the frame is bottom-field-first
5486 @item consumed_sample_n @emph{(audio only)}
5487 the number of selected samples before the current frame
5489 @item samples_n @emph{(audio only)}
5490 the number of samples in the current frame
5492 @item sample_rate @emph{(audio only)}
5493 the input sample rate
5496 1 if the filtered frame is a key-frame, 0 otherwise
5499 the position in the file of the filtered frame, -1 if the information
5500 is not available (e.g. for synthetic video)
5502 @item scene @emph{(video only)}
5503 value between 0 and 1 to indicate a new scene; a low value reflects a low
5504 probability for the current frame to introduce a new scene, while a higher
5505 value means the current frame is more likely to be one (see the example below)
5509 The default value of the select expression is "1".
5511 @subsection Examples
5515 Select all frames in input:
5520 The example above is the same as:
5532 Select only I-frames:
5534 select='eq(pict_type\,I)'
5538 Select one frame every 100:
5540 select='not(mod(n\,100))'
5544 Select only frames contained in the 10-20 time interval:
5546 select='gte(t\,10)*lte(t\,20)'
5550 Select only I frames contained in the 10-20 time interval:
5552 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
5556 Select frames with a minimum distance of 10 seconds:
5558 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
5562 Use aselect to select only audio frames with samples number > 100:
5564 aselect='gt(samples_n\,100)'
5568 Create a mosaic of the first scenes:
5570 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
5573 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
5577 @section asendcmd, sendcmd
5579 Send commands to filters in the filtergraph.
5581 These filters read commands to be sent to other filters in the
5584 @code{asendcmd} must be inserted between two audio filters,
5585 @code{sendcmd} must be inserted between two video filters, but apart
5586 from that they act the same way.
5588 The specification of commands can be provided in the filter arguments
5589 with the @var{commands} option, or in a file specified by the
5590 @var{filename} option.
5592 These filters accept the following options:
5595 Set the commands to be read and sent to the other filters.
5597 Set the filename of the commands to be read and sent to the other
5601 @subsection Commands syntax
5603 A commands description consists of a sequence of interval
5604 specifications, comprising a list of commands to be executed when a
5605 particular event related to that interval occurs. The occurring event
5606 is typically the current frame time entering or leaving a given time
5609 An interval is specified by the following syntax:
5611 @var{START}[-@var{END}] @var{COMMANDS};
5614 The time interval is specified by the @var{START} and @var{END} times.
5615 @var{END} is optional and defaults to the maximum time.
5617 The current frame time is considered within the specified interval if
5618 it is included in the interval [@var{START}, @var{END}), that is when
5619 the time is greater or equal to @var{START} and is lesser than
5622 @var{COMMANDS} consists of a sequence of one or more command
5623 specifications, separated by ",", relating to that interval. The
5624 syntax of a command specification is given by:
5626 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
5629 @var{FLAGS} is optional and specifies the type of events relating to
5630 the time interval which enable sending the specified command, and must
5631 be a non-null sequence of identifier flags separated by "+" or "|" and
5632 enclosed between "[" and "]".
5634 The following flags are recognized:
5637 The command is sent when the current frame timestamp enters the
5638 specified interval. In other words, the command is sent when the
5639 previous frame timestamp was not in the given interval, and the
5643 The command is sent when the current frame timestamp leaves the
5644 specified interval. In other words, the command is sent when the
5645 previous frame timestamp was in the given interval, and the
5649 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
5652 @var{TARGET} specifies the target of the command, usually the name of
5653 the filter class or a specific filter instance name.
5655 @var{COMMAND} specifies the name of the command for the target filter.
5657 @var{ARG} is optional and specifies the optional list of argument for
5658 the given @var{COMMAND}.
5660 Between one interval specification and another, whitespaces, or
5661 sequences of characters starting with @code{#} until the end of line,
5662 are ignored and can be used to annotate comments.
5664 A simplified BNF description of the commands specification syntax
5667 @var{COMMAND_FLAG} ::= "enter" | "leave"
5668 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
5669 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
5670 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
5671 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
5672 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
5675 @subsection Examples
5679 Specify audio tempo change at second 4:
5681 asendcmd=c='4.0 atempo tempo 1.5',atempo
5685 Specify a list of drawtext and hue commands in a file.
5687 # show text in the interval 5-10
5688 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
5689 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
5691 # desaturate the image in the interval 15-20
5692 15.0-20.0 [enter] hue reinit s=0,
5693 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
5694 [leave] hue reinit s=1,
5695 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
5697 # apply an exponential saturation fade-out effect, starting from time 25
5698 25 [enter] hue s=exp(t-25)
5701 A filtergraph allowing to read and process the above command list
5702 stored in a file @file{test.cmd}, can be specified with:
5704 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
5709 @section asetpts, setpts
5711 Change the PTS (presentation timestamp) of the input frames.
5713 @code{asetpts} works on audio frames, @code{setpts} on video frames.
5715 Accept in input an expression evaluated through the eval API, which
5716 can contain the following constants:
5720 frame rate, only defined for constant frame-rate video
5723 the presentation timestamp in input
5726 the count of the input frame, starting from 0.
5728 @item NB_CONSUMED_SAMPLES
5729 the number of consumed samples, not including the current frame (only
5733 the number of samples in the current frame (only audio)
5739 the PTS of the first frame
5742 the time in seconds of the first frame
5745 tell if the current frame is interlaced
5748 the time in seconds of the current frame
5754 original position in the file of the frame, or undefined if undefined
5755 for the current frame
5761 previous input time in seconds
5767 previous output time in seconds
5770 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
5774 wallclock (RTC) time at the start of the movie in microseconds
5777 @subsection Examples
5781 Start counting PTS from zero
5787 Apply fast motion effect:
5793 Apply slow motion effect:
5799 Set fixed rate of 25 frames per second:
5805 Set fixed rate 25 fps with some jitter:
5807 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
5811 Apply an offset of 10 seconds to the input PTS:
5817 Generate timestamps from a "live source" and rebase onto the current timebase:
5819 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
5825 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
5826 it unchanged. By default, it logs a message at a frequency of 10Hz with the
5827 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
5828 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
5830 The filter also has a video output (see the @var{video} option) with a real
5831 time graph to observe the loudness evolution. The graphic contains the logged
5832 message mentioned above, so it is not printed anymore when this option is set,
5833 unless the verbose logging is set. The main graphing area contains the
5834 short-term loudness (3 seconds of analysis), and the gauge on the right is for
5835 the momentary loudness (400 milliseconds).
5837 More information about the Loudness Recommendation EBU R128 on
5838 @url{http://tech.ebu.ch/loudness}.
5840 The filter accepts the following named parameters:
5845 Activate the video output. The audio stream is passed unchanged whether this
5846 option is set or no. The video stream will be the first output stream if
5847 activated. Default is @code{0}.
5850 Set the video size. This option is for video only. Default and minimum
5851 resolution is @code{640x480}.
5854 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
5855 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
5856 other integer value between this range is allowed.
5860 Example of real-time graph using @command{ffplay}, with a EBU scale meter +18:
5862 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
5865 Run an analysis with @command{ffmpeg}:
5867 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
5870 @section settb, asettb
5872 Set the timebase to use for the output frames timestamps.
5873 It is mainly useful for testing timebase configuration.
5875 It accepts in input an arithmetic expression representing a rational.
5876 The expression can contain the constants "AVTB" (the
5877 default timebase), "intb" (the input timebase) and "sr" (the sample rate,
5880 The default value for the input is "intb".
5882 @subsection Examples
5886 Set the timebase to 1/25:
5892 Set the timebase to 1/10:
5898 Set the timebase to 1001/1000:
5904 Set the timebase to 2*intb:
5910 Set the default timebase value:
5918 Concatenate audio and video streams, joining them together one after the
5921 The filter works on segments of synchronized video and audio streams. All
5922 segments must have the same number of streams of each type, and that will
5923 also be the number of streams at output.
5925 The filter accepts the following named parameters:
5929 Set the number of segments. Default is 2.
5932 Set the number of output video streams, that is also the number of video
5933 streams in each segment. Default is 1.
5936 Set the number of output audio streams, that is also the number of video
5937 streams in each segment. Default is 0.
5940 Activate unsafe mode: do not fail if segments have a different format.
5944 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
5945 @var{a} audio outputs.
5947 There are @var{n}×(@var{v}+@var{a}) inputs: first the inputs for the first
5948 segment, in the same order as the outputs, then the inputs for the second
5951 Related streams do not always have exactly the same duration, for various
5952 reasons including codec frame size or sloppy authoring. For that reason,
5953 related synchronized streams (e.g. a video and its audio track) should be
5954 concatenated at once. The concat filter will use the duration of the longest
5955 stream in each segment (except the last one), and if necessary pad shorter
5956 audio streams with silence.
5958 For this filter to work correctly, all segments must start at timestamp 0.
5960 All corresponding streams must have the same parameters in all segments; the
5961 filtering system will automatically select a common pixel format for video
5962 streams, and a common sample format, sample rate and channel layout for
5963 audio streams, but other settings, such as resolution, must be converted
5964 explicitly by the user.
5966 Different frame rates are acceptable but will result in variable frame rate
5967 at output; be sure to configure the output file to handle it.
5972 Concatenate an opening, an episode and an ending, all in bilingual version
5973 (video in stream 0, audio in streams 1 and 2):
5975 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
5976 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
5977 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
5978 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
5982 Concatenate two parts, handling audio and video separately, using the
5983 (a)movie sources, and adjusting the resolution:
5985 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
5986 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
5987 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
5989 Note that a desync will happen at the stitch if the audio and video streams
5990 do not have exactly the same duration in the first file.
5994 @section showspectrum
5996 Convert input audio to a video output, representing the audio frequency
5999 The filter accepts the following named parameters:
6002 Specify the video size for the output. Default value is @code{640x480}.
6004 Specify if the spectrum should slide along the window. Default value is
6008 The usage is very similar to the showwaves filter; see the examples in that
6013 Convert input audio to a video output, representing the samples waves.
6015 The filter accepts the following named parameters:
6020 Available values are:
6023 Draw a point for each sample.
6026 Draw a vertical line for each sample.
6029 Default value is @code{point}.
6032 Set the number of samples which are printed on the same column. A
6033 larger value will decrease the frame rate. Must be a positive
6034 integer. This option can be set only if the value for @var{rate}
6035 is not explicitly specified.
6038 Set the (approximate) output frame rate. This is done by setting the
6039 option @var{n}. Default value is "25".
6042 Specify the video size for the output. Default value is "600x240".
6045 Some examples follow.
6048 Output the input file audio and the corresponding video representation
6051 amovie=a.mp3,asplit[out0],showwaves[out1]
6055 Create a synthetic signal and show it with showwaves, forcing a
6056 framerate of 30 frames per second:
6058 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
6062 @c man end MULTIMEDIA FILTERS
6064 @chapter Multimedia Sources
6065 @c man begin MULTIMEDIA SOURCES
6067 Below is a description of the currently available multimedia sources.
6071 This is the same as @ref{movie} source, except it selects an audio
6077 Read audio and/or video stream(s) from a movie container.
6079 It accepts the syntax: @var{movie_name}[:@var{options}] where
6080 @var{movie_name} is the name of the resource to read (not necessarily
6081 a file but also a device or a stream accessed through some protocol),
6082 and @var{options} is an optional sequence of @var{key}=@var{value}
6083 pairs, separated by ":".
6085 The description of the accepted options follows.
6089 @item format_name, f
6090 Specifies the format assumed for the movie to read, and can be either
6091 the name of a container or an input device. If not specified the
6092 format is guessed from @var{movie_name} or by probing.
6094 @item seek_point, sp
6095 Specifies the seek point in seconds, the frames will be output
6096 starting from this seek point, the parameter is evaluated with
6097 @code{av_strtod} so the numerical value may be suffixed by an IS
6098 postfix. Default value is "0".
6101 Specifies the streams to read. Several streams can be specified,
6102 separated by "+". The source will then have as many outputs, in the
6103 same order. The syntax is explained in the ``Stream specifiers''
6104 section in the ffmpeg manual. Two special names, "dv" and "da" specify
6105 respectively the default (best suited) video and audio stream. Default
6106 is "dv", or "da" if the filter is called as "amovie".
6108 @item stream_index, si
6109 Specifies the index of the video stream to read. If the value is -1,
6110 the best suited video stream will be automatically selected. Default
6111 value is "-1". Deprecated. If the filter is called "amovie", it will select
6112 audio instead of video.
6115 Specifies how many times to read the stream in sequence.
6116 If the value is less than 1, the stream will be read again and again.
6117 Default value is "1".
6119 Note that when the movie is looped the source timestamps are not
6120 changed, so it will generate non monotonically increasing timestamps.
6123 This filter allows to overlay a second video on top of main input of
6124 a filtergraph as shown in this graph:
6126 input -----------> deltapts0 --> overlay --> output
6129 movie --> scale--> deltapts1 -------+
6132 Some examples follow.
6136 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
6137 on top of the input labelled as "in":
6139 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
6140 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
6144 Read from a video4linux2 device, and overlay it on top of the input
6147 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
6148 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
6152 Read the first video stream and the audio stream with id 0x81 from
6153 dvd.vob; the video is connected to the pad named "video" and the audio is
6154 connected to the pad named "audio":
6156 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
6160 @c man end MULTIMEDIA SOURCES