1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 In libavfilter, a filter can have multiple inputs and multiple
8 To illustrate the sorts of things that are possible, we consider the
12 input --> split ---------------------> overlay --> output
15 +-----> crop --> vflip -------+
18 This filtergraph splits the input stream in two streams, sends one
19 stream through the crop filter and the vflip filter before merging it
20 back with the other stream by overlaying it on top. You can use the
21 following command to achieve this:
24 ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT
27 The result will be that in output the top half of the video is mirrored
30 Filters in the same linear chain are separated by commas, and distinct
31 linear chains of filters are separated by semicolons. In our example,
32 @var{crop,vflip} are in one linear chain, @var{split} and
33 @var{overlay} are separately in another. The points where the linear
34 chains join are labelled by names enclosed in square brackets. In the
35 example, the split filter generates two outputs that are associated to
36 the labels @var{[main]} and @var{[tmp]}.
38 The stream sent to the second output of @var{split}, labelled as
39 @var{[tmp]}, is processed through the @var{crop} filter, which crops
40 away the lower half part of the video, and then vertically flipped. The
41 @var{overlay} filter takes in input the first unchanged output of the
42 split filter (which was labelled as @var{[main]}), and overlay on its
43 lower half the output generated by the @var{crop,vflip} filterchain.
45 Some filters take in input a list of parameters: they are specified
46 after the filter name and an equal sign, and are separated from each other
49 There exist so-called @var{source filters} that do not have an
50 audio/video input, and @var{sink filters} that will not have audio/video
53 @c man end FILTERING INTRODUCTION
56 @c man begin GRAPH2DOT
58 The @file{graph2dot} program included in the FFmpeg @file{tools}
59 directory can be used to parse a filtergraph description and issue a
60 corresponding textual representation in the dot language.
67 to see how to use @file{graph2dot}.
69 You can then pass the dot description to the @file{dot} program (from
70 the graphviz suite of programs) and obtain a graphical representation
73 For example the sequence of commands:
75 echo @var{GRAPH_DESCRIPTION} | \
76 tools/graph2dot -o graph.tmp && \
77 dot -Tpng graph.tmp -o graph.png && \
81 can be used to create and display an image representing the graph
82 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
83 a complete self-contained graph, with its inputs and outputs explicitly defined.
84 For example if your command line is of the form:
86 ffmpeg -i infile -vf scale=640:360 outfile
88 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
90 nullsrc,scale=640:360,nullsink
92 you may also need to set the @var{nullsrc} parameters and add a @var{format}
93 filter in order to simulate a specific input file.
97 @chapter Filtergraph description
98 @c man begin FILTERGRAPH DESCRIPTION
100 A filtergraph is a directed graph of connected filters. It can contain
101 cycles, and there can be multiple links between a pair of
102 filters. Each link has one input pad on one side connecting it to one
103 filter from which it takes its input, and one output pad on the other
104 side connecting it to the one filter accepting its output.
106 Each filter in a filtergraph is an instance of a filter class
107 registered in the application, which defines the features and the
108 number of input and output pads of the filter.
110 A filter with no input pads is called a "source", a filter with no
111 output pads is called a "sink".
113 @anchor{Filtergraph syntax}
114 @section Filtergraph syntax
116 A filtergraph can be represented using a textual representation, which is
117 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
118 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
119 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
120 @file{libavfilter/avfilter.h}.
122 A filterchain consists of a sequence of connected filters, each one
123 connected to the previous one in the sequence. A filterchain is
124 represented by a list of ","-separated filter descriptions.
126 A filtergraph consists of a sequence of filterchains. A sequence of
127 filterchains is represented by a list of ";"-separated filterchain
130 A filter is represented by a string of the form:
131 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
133 @var{filter_name} is the name of the filter class of which the
134 described filter is an instance of, and has to be the name of one of
135 the filter classes registered in the program.
136 The name of the filter class is optionally followed by a string
139 @var{arguments} is a string which contains the parameters used to
140 initialize the filter instance. It may have one of the following forms:
144 A ':'-separated list of @var{key=value} pairs.
147 A ':'-separated list of @var{value}. In this case, the keys are assumed to be
148 the option names in the order they are declared. E.g. the @code{fade} filter
149 declares three options in this order -- @option{type}, @option{start_frame} and
150 @option{nb_frames}. Then the parameter list @var{in:0:30} means that the value
151 @var{in} is assigned to the option @option{type}, @var{0} to
152 @option{start_frame} and @var{30} to @option{nb_frames}.
155 A ':'-separated list of mixed direct @var{value} and long @var{key=value}
156 pairs. The direct @var{value} must precede the @var{key=value} pairs, and
157 follow the same constraints order of the previous point. The following
158 @var{key=value} pairs can be set in any preferred order.
162 If the option value itself is a list of items (e.g. the @code{format} filter
163 takes a list of pixel formats), the items in the list are usually separated by
166 The list of arguments can be quoted using the character "'" as initial
167 and ending mark, and the character '\' for escaping the characters
168 within the quoted text; otherwise the argument string is considered
169 terminated when the next special character (belonging to the set
170 "[]=;,") is encountered.
172 The name and arguments of the filter are optionally preceded and
173 followed by a list of link labels.
174 A link label allows to name a link and associate it to a filter output
175 or input pad. The preceding labels @var{in_link_1}
176 ... @var{in_link_N}, are associated to the filter input pads,
177 the following labels @var{out_link_1} ... @var{out_link_M}, are
178 associated to the output pads.
180 When two link labels with the same name are found in the
181 filtergraph, a link between the corresponding input and output pad is
184 If an output pad is not labelled, it is linked by default to the first
185 unlabelled input pad of the next filter in the filterchain.
186 For example in the filterchain:
188 nullsrc, split[L1], [L2]overlay, nullsink
190 the split filter instance has two output pads, and the overlay filter
191 instance two input pads. The first output pad of split is labelled
192 "L1", the first input pad of overlay is labelled "L2", and the second
193 output pad of split is linked to the second input pad of overlay,
194 which are both unlabelled.
196 In a complete filterchain all the unlabelled filter input and output
197 pads must be connected. A filtergraph is considered valid if all the
198 filter input and output pads of all the filterchains are connected.
200 Libavfilter will automatically insert scale filters where format
201 conversion is required. It is possible to specify swscale flags
202 for those automatically inserted scalers by prepending
203 @code{sws_flags=@var{flags};}
204 to the filtergraph description.
206 Follows a BNF description for the filtergraph syntax:
208 @var{NAME} ::= sequence of alphanumeric characters and '_'
209 @var{LINKLABEL} ::= "[" @var{NAME} "]"
210 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
211 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
212 @var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
213 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
214 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
217 @section Notes on filtergraph escaping
219 Some filter arguments require the use of special characters, typically
220 @code{:} to separate key=value pairs in a named options list. In this
221 case the user should perform a first level escaping when specifying
222 the filter arguments. For example, consider the following literal
223 string to be embedded in the @ref{drawtext} filter arguments:
225 this is a 'string': may contain one, or more, special characters
228 Since @code{:} is special for the filter arguments syntax, it needs to
229 be escaped, so you get:
231 text=this is a \'string\'\: may contain one, or more, special characters
234 A second level of escaping is required when embedding the filter
235 arguments in a filtergraph description, in order to escape all the
236 filtergraph special characters. Thus the example above becomes:
238 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
241 Finally an additional level of escaping may be needed when writing the
242 filtergraph description in a shell command, which depends on the
243 escaping rules of the adopted shell. For example, assuming that
244 @code{\} is special and needs to be escaped with another @code{\}, the
245 previous string will finally result in:
247 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
250 Sometimes, it might be more convenient to employ quoting in place of
251 escaping. For example the string:
253 Caesar: tu quoque, Brute, fili mi
256 Can be quoted in the filter arguments as:
258 text='Caesar: tu quoque, Brute, fili mi'
261 And finally inserted in a filtergraph like:
263 drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
266 See the ``Quoting and escaping'' section in the ffmpeg-utils manual
267 for more information about the escaping and quoting rules adopted by
270 @chapter Timeline editing
272 Some filters support a generic @option{enable} option. For the filters
273 supporting timeline editing, this option can be set to an expression which is
274 evaluated before sending a frame to the filter. If the evaluation is non-zero,
275 the filter will be enabled, otherwise the frame will be sent unchanged to the
276 next filter in the filtergraph.
278 The expression accepts the following values:
281 timestamp expressed in seconds, NAN if the input timestamp is unknown
284 sequential number of the input frame, starting from 0
287 the position in the file of the input frame, NAN if unknown
290 Additionally, these filters support an @option{enable} command that can be used
291 to re-define the expression.
293 Like any other filtering option, the @option{enable} option follows the same
296 For example, to enable a blur filter (@ref{smartblur}) from 10 seconds to 3
297 minutes, and a @ref{curves} filter starting at 3 seconds:
299 smartblur = enable='between(t,10,3*60)',
300 curves = enable='gte(t,3)' : preset=cross_process
303 @c man end FILTERGRAPH DESCRIPTION
305 @chapter Audio Filters
306 @c man begin AUDIO FILTERS
308 When you configure your FFmpeg build, you can disable any of the
309 existing filters using @code{--disable-filters}.
310 The configure output will show the audio filters included in your
313 Below is a description of the currently available audio filters.
317 Convert the input audio format to the specified formats.
319 @emph{This filter is deprecated. Use @ref{aformat} instead.}
321 The filter accepts a string of the form:
322 "@var{sample_format}:@var{channel_layout}".
324 @var{sample_format} specifies the sample format, and can be a string or the
325 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
326 suffix for a planar sample format.
328 @var{channel_layout} specifies the channel layout, and can be a string
329 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
331 The special parameter "auto", signifies that the filter will
332 automatically select the output format depending on the output filter.
338 Convert input to float, planar, stereo:
344 Convert input to unsigned 8-bit, automatically select out channel layout:
352 Apply fade-in/out effect to input audio.
354 A description of the accepted parameters follows.
358 Specify the effect type, can be either @code{in} for fade-in, or
359 @code{out} for a fade-out effect. Default is @code{in}.
361 @item start_sample, ss
362 Specify the number of the start sample for starting to apply the fade
363 effect. Default is 0.
366 Specify the number of samples for which the fade effect has to last. At
367 the end of the fade-in effect the output audio will have the same
368 volume as the input audio, at the end of the fade-out transition
369 the output audio will be silence. Default is 44100.
372 Specify time for starting to apply the fade effect. Default is 0.
373 The accepted syntax is:
375 [-]HH[:MM[:SS[.m...]]]
378 See also the function @code{av_parse_time()}.
379 If set this option is used instead of @var{start_sample} one.
382 Specify the duration for which the fade effect has to last. Default is 0.
383 The accepted syntax is:
385 [-]HH[:MM[:SS[.m...]]]
388 See also the function @code{av_parse_time()}.
389 At the end of the fade-in effect the output audio will have the same
390 volume as the input audio, at the end of the fade-out transition
391 the output audio will be silence.
392 If set this option is used instead of @var{nb_samples} one.
395 Set curve for fade transition.
397 It accepts the following values:
400 select triangular, linear slope (default)
402 select quarter of sine wave
404 select half of sine wave
406 select exponential sine wave
410 select inverted parabola
426 Fade in first 15 seconds of audio:
432 Fade out last 25 seconds of a 900 seconds audio:
434 afade=t=out:st=875:d=25
441 Set output format constraints for the input audio. The framework will
442 negotiate the most appropriate format to minimize conversions.
444 The filter accepts the following named parameters:
448 A '|'-separated list of requested sample formats.
451 A '|'-separated list of requested sample rates.
453 @item channel_layouts
454 A '|'-separated list of requested channel layouts.
458 If a parameter is omitted, all values are allowed.
460 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
462 aformat=sample_fmts=u8|s16:channel_layouts=stereo
467 Apply a two-pole all-pass filter with central frequency (in Hz)
468 @var{frequency}, and filter-width @var{width}.
469 An all-pass filter changes the audio's frequency to phase relationship
470 without changing its frequency to amplitude relationship.
472 The filter accepts the following options:
479 Set method to specify band-width of filter.
492 Specify the band-width of a filter in width_type units.
497 Merge two or more audio streams into a single multi-channel stream.
499 The filter accepts the following options:
504 Set the number of inputs. Default is 2.
508 If the channel layouts of the inputs are disjoint, and therefore compatible,
509 the channel layout of the output will be set accordingly and the channels
510 will be reordered as necessary. If the channel layouts of the inputs are not
511 disjoint, the output will have all the channels of the first input then all
512 the channels of the second input, in that order, and the channel layout of
513 the output will be the default value corresponding to the total number of
516 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
517 is FC+BL+BR, then the output will be in 5.1, with the channels in the
518 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
519 first input, b1 is the first channel of the second input).
521 On the other hand, if both input are in stereo, the output channels will be
522 in the default order: a1, a2, b1, b2, and the channel layout will be
523 arbitrarily set to 4.0, which may or may not be the expected value.
525 All inputs must have the same sample rate, and format.
527 If inputs do not have the same duration, the output will stop with the
534 Merge two mono files into a stereo stream:
536 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
540 Multiple merges assuming 1 video stream and 6 audio streams in @file{input.mkv}:
542 ffmpeg -i input.mkv -filter_complex "[0:1][0:2][0:3][0:4][0:5][0:6] amerge=inputs=6" -c:a pcm_s16le output.mkv
548 Mixes multiple audio inputs into a single output.
552 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
554 will mix 3 input audio streams to a single output with the same duration as the
555 first input and a dropout transition time of 3 seconds.
557 The filter accepts the following named parameters:
561 Number of inputs. If unspecified, it defaults to 2.
564 How to determine the end-of-stream.
568 Duration of longest input. (default)
571 Duration of shortest input.
574 Duration of first input.
578 @item dropout_transition
579 Transition time, in seconds, for volume renormalization when an input
580 stream ends. The default value is 2 seconds.
586 Pass the audio source unchanged to the output.
590 Pad the end of a audio stream with silence, this can be used together with
591 -shortest to extend audio streams to the same length as the video stream.
594 Add a phasing effect to the input audio.
596 A phaser filter creates series of peaks and troughs in the frequency spectrum.
597 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
599 A description of the accepted parameters follows.
603 Set input gain. Default is 0.4.
606 Set output gain. Default is 0.74
609 Set delay in milliseconds. Default is 3.0.
612 Set decay. Default is 0.4.
615 Set modulation speed in Hz. Default is 0.5.
618 Set modulation type. Default is triangular.
620 It accepts the following values:
630 Resample the input audio to the specified parameters, using the
631 libswresample library. If none are specified then the filter will
632 automatically convert between its input and output.
634 This filter is also able to stretch/squeeze the audio data to make it match
635 the timestamps or to inject silence / cut out audio to make it match the
636 timestamps, do a combination of both or do neither.
638 The filter accepts the syntax
639 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
640 expresses a sample rate and @var{resampler_options} is a list of
641 @var{key}=@var{value} pairs, separated by ":". See the
642 ffmpeg-resampler manual for the complete list of supported options.
648 Resample the input audio to 44100Hz:
654 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
655 samples per second compensation:
661 @section asetnsamples
663 Set the number of samples per each output audio frame.
665 The last output packet may contain a different number of samples, as
666 the filter will flush all the remaining samples when the input audio
669 The filter accepts the following options:
673 @item nb_out_samples, n
674 Set the number of frames per each output audio frame. The number is
675 intended as the number of samples @emph{per each channel}.
676 Default value is 1024.
679 If set to 1, the filter will pad the last audio frame with zeroes, so
680 that the last frame will contain the same number of samples as the
681 previous ones. Default value is 1.
684 For example, to set the number of per-frame samples to 1234 and
685 disable padding for the last frame, use:
687 asetnsamples=n=1234:p=0
692 Set the sample rate without altering the PCM data.
693 This will result in a change of speed and pitch.
695 The filter accepts the following options:
699 Set the output sample rate. Default is 44100 Hz.
704 Show a line containing various information for each input audio frame.
705 The input audio is not modified.
707 The shown line contains a sequence of key/value pairs of the form
708 @var{key}:@var{value}.
710 A description of each shown parameter follows:
714 sequential number of the input frame, starting from 0
717 Presentation timestamp of the input frame, in time base units; the time base
718 depends on the filter input pad, and is usually 1/@var{sample_rate}.
721 presentation timestamp of the input frame in seconds
724 position of the frame in the input stream, -1 if this information in
725 unavailable and/or meaningless (for example in case of synthetic audio)
734 sample rate for the audio frame
737 number of samples (per channel) in the frame
740 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
741 the data is treated as if all the planes were concatenated.
743 @item plane_checksums
744 A list of Adler-32 checksums for each data plane.
749 Display time domain statistical information about the audio channels.
750 Statistics are calculated and displayed for each audio channel and,
751 where applicable, an overall figure is also given.
753 The filter accepts the following option:
756 Short window length in seconds, used for peak and trough RMS measurement.
757 Default is @code{0.05} (50 miliseconds). Allowed range is @code{[0.1 - 10]}.
760 A description of each shown parameter follows:
764 Mean amplitude displacement from zero.
767 Minimal sample level.
770 Maximal sample level.
774 Standard peak and RMS level measured in dBFS.
778 Peak and trough values for RMS level measured over a short window.
781 Standard ratio of peak to RMS level (note: not in dB).
784 Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels
785 (i.e. either @var{Min level} or @var{Max level}).
788 Number of occasions (not the number of samples) that the signal attained either
789 @var{Min level} or @var{Max level}.
794 Forward two audio streams and control the order the buffers are forwarded.
796 The filter accepts the following options:
800 Set the expression deciding which stream should be
801 forwarded next: if the result is negative, the first stream is forwarded; if
802 the result is positive or zero, the second stream is forwarded. It can use
803 the following variables:
807 number of buffers forwarded so far on each stream
809 number of samples forwarded so far on each stream
811 current timestamp of each stream
814 The default value is @code{t1-t2}, which means to always forward the stream
815 that has a smaller timestamp.
820 Stress-test @code{amerge} by randomly sending buffers on the wrong
821 input, while avoiding too much of a desynchronization:
823 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
824 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
830 Synchronize audio data with timestamps by squeezing/stretching it and/or
831 dropping samples/adding silence when needed.
833 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
835 The filter accepts the following named parameters:
839 Enable stretching/squeezing the data to make it match the timestamps. Disabled
840 by default. When disabled, time gaps are covered with silence.
843 Minimum difference between timestamps and audio data (in seconds) to trigger
844 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
845 this filter, try setting this parameter to 0.
848 Maximum compensation in samples per second. Relevant only with compensate=1.
852 Assume the first pts should be this value. The time base is 1 / sample rate.
853 This allows for padding/trimming at the start of stream. By default, no
854 assumption is made about the first frame's expected pts, so no padding or
855 trimming is done. For example, this could be set to 0 to pad the beginning with
856 silence if an audio stream starts after the video stream or to trim any samples
857 with a negative pts due to encoder delay.
865 The filter accepts exactly one parameter, the audio tempo. If not
866 specified then the filter will assume nominal 1.0 tempo. Tempo must
867 be in the [0.5, 2.0] range.
873 Slow down audio to 80% tempo:
879 To speed up audio to 125% tempo:
887 Trim the input so that the output contains one continuous subpart of the input.
889 This filter accepts the following options:
892 Timestamp (in seconds) of the start of the kept section. I.e. the audio sample
893 with the timestamp @var{start} will be the first sample in the output.
896 Timestamp (in seconds) of the first audio sample that will be dropped. I.e. the
897 audio sample immediately preceding the one with the timestamp @var{end} will be
898 the last sample in the output.
901 Same as @var{start}, except this option sets the start timestamp in samples
905 Same as @var{end}, except this option sets the end timestamp in samples instead
909 Maximum duration of the output in seconds.
912 Number of the first sample that should be passed to output.
915 Number of the first sample that should be dropped.
918 Note that the first two sets of the start/end options and the @option{duration}
919 option look at the frame timestamp, while the _sample options simply count the
920 samples that pass through the filter. So start/end_pts and start/end_sample will
921 give different results when the timestamps are wrong, inexact or do not start at
922 zero. Also note that this filter does not modify the timestamps. If you wish
923 that the output timestamps start at zero, insert the asetpts filter after the
926 If multiple start or end options are set, this filter tries to be greedy and
927 keep all samples that match at least one of the specified constraints. To keep
928 only the part that matches all the constraints at once, chain multiple atrim
931 The defaults are such that all the input is kept. So it is possible to set e.g.
932 just the end values to keep everything before the specified time.
937 drop everything except the second minute of input
939 ffmpeg -i INPUT -af atrim=60:120
943 keep only the first 1000 samples
945 ffmpeg -i INPUT -af atrim=end_sample=1000
952 Apply a two-pole Butterworth band-pass filter with central
953 frequency @var{frequency}, and (3dB-point) band-width width.
954 The @var{csg} option selects a constant skirt gain (peak gain = Q)
955 instead of the default: constant 0dB peak gain.
956 The filter roll off at 6dB per octave (20dB per decade).
958 The filter accepts the following options:
962 Set the filter's central frequency. Default is @code{3000}.
965 Constant skirt gain if set to 1. Defaults to 0.
968 Set method to specify band-width of filter.
981 Specify the band-width of a filter in width_type units.
986 Apply a two-pole Butterworth band-reject filter with central
987 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
988 The filter roll off at 6dB per octave (20dB per decade).
990 The filter accepts the following options:
994 Set the filter's central frequency. Default is @code{3000}.
997 Set method to specify band-width of filter.
1010 Specify the band-width of a filter in width_type units.
1015 Boost or cut the bass (lower) frequencies of the audio using a two-pole
1016 shelving filter with a response similar to that of a standard
1017 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
1019 The filter accepts the following options:
1023 Give the gain at 0 Hz. Its useful range is about -20
1024 (for a large cut) to +20 (for a large boost).
1025 Beware of clipping when using a positive gain.
1028 Set the filter's central frequency and so can be used
1029 to extend or reduce the frequency range to be boosted or cut.
1030 The default value is @code{100} Hz.
1033 Set method to specify band-width of filter.
1046 Determine how steep is the filter's shelf transition.
1051 Apply a biquad IIR filter with the given coefficients.
1052 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
1053 are the numerator and denominator coefficients respectively.
1057 Remap input channels to new locations.
1059 This filter accepts the following named parameters:
1061 @item channel_layout
1062 Channel layout of the output stream.
1065 Map channels from input to output. The argument is a '|'-separated list of
1066 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1067 @var{in_channel} form. @var{in_channel} can be either the name of the input
1068 channel (e.g. FL for front left) or its index in the input channel layout.
1069 @var{out_channel} is the name of the output channel or its index in the output
1070 channel layout. If @var{out_channel} is not given then it is implicitly an
1071 index, starting with zero and increasing by one for each mapping.
1074 If no mapping is present, the filter will implicitly map input channels to
1075 output channels preserving index.
1077 For example, assuming a 5.1+downmix input MOV file
1079 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1081 will create an output WAV file tagged as stereo from the downmix channels of
1084 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1086 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
1089 @section channelsplit
1091 Split each channel in input audio stream into a separate output stream.
1093 This filter accepts the following named parameters:
1095 @item channel_layout
1096 Channel layout of the input stream. Default is "stereo".
1099 For example, assuming a stereo input MP3 file
1101 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1103 will create an output Matroska file with two audio streams, one containing only
1104 the left channel and the other the right channel.
1106 To split a 5.1 WAV file into per-channel files
1108 ffmpeg -i in.wav -filter_complex
1109 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1110 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1111 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1117 Make audio easier to listen to on headphones.
1119 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1120 so that when listened to on headphones the stereo image is moved from
1121 inside your head (standard for headphones) to outside and in front of
1122 the listener (standard for speakers).
1128 Apply a two-pole peaking equalisation (EQ) filter. With this
1129 filter, the signal-level at and around a selected frequency can
1130 be increased or decreased, whilst (unlike bandpass and bandreject
1131 filters) that at all other frequencies is unchanged.
1133 In order to produce complex equalisation curves, this filter can
1134 be given several times, each with a different central frequency.
1136 The filter accepts the following options:
1140 Set the filter's central frequency in Hz.
1143 Set method to specify band-width of filter.
1156 Specify the band-width of a filter in width_type units.
1159 Set the required gain or attenuation in dB.
1160 Beware of clipping when using a positive gain.
1165 Apply a high-pass filter with 3dB point frequency.
1166 The filter can be either single-pole, or double-pole (the default).
1167 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
1169 The filter accepts the following options:
1173 Set frequency in Hz. Default is 3000.
1176 Set number of poles. Default is 2.
1179 Set method to specify band-width of filter.
1192 Specify the band-width of a filter in width_type units.
1193 Applies only to double-pole filter.
1194 The default is 0.707q and gives a Butterworth response.
1199 Join multiple input streams into one multi-channel stream.
1201 The filter accepts the following named parameters:
1205 Number of input streams. Defaults to 2.
1207 @item channel_layout
1208 Desired output channel layout. Defaults to stereo.
1211 Map channels from inputs to output. The argument is a '|'-separated list of
1212 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1213 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1214 can be either the name of the input channel (e.g. FL for front left) or its
1215 index in the specified input stream. @var{out_channel} is the name of the output
1219 The filter will attempt to guess the mappings when those are not specified
1220 explicitly. It does so by first trying to find an unused matching input channel
1221 and if that fails it picks the first unused input channel.
1223 E.g. to join 3 inputs (with properly set channel layouts)
1225 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1228 To build a 5.1 output from 6 single-channel streams:
1230 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1231 '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'
1237 Apply a low-pass filter with 3dB point frequency.
1238 The filter can be either single-pole or double-pole (the default).
1239 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
1241 The filter accepts the following options:
1245 Set frequency in Hz. Default is 500.
1248 Set number of poles. Default is 2.
1251 Set method to specify band-width of filter.
1264 Specify the band-width of a filter in width_type units.
1265 Applies only to double-pole filter.
1266 The default is 0.707q and gives a Butterworth response.
1271 Mix channels with specific gain levels. The filter accepts the output
1272 channel layout followed by a set of channels definitions.
1274 This filter is also designed to remap efficiently the channels of an audio
1277 The filter accepts parameters of the form:
1278 "@var{l}:@var{outdef}:@var{outdef}:..."
1282 output channel layout or number of channels
1285 output channel specification, of the form:
1286 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1289 output channel to define, either a channel name (FL, FR, etc.) or a channel
1290 number (c0, c1, etc.)
1293 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1296 input channel to use, see out_name for details; it is not possible to mix
1297 named and numbered input channels
1300 If the `=' in a channel specification is replaced by `<', then the gains for
1301 that specification will be renormalized so that the total is 1, thus
1302 avoiding clipping noise.
1304 @subsection Mixing examples
1306 For example, if you want to down-mix from stereo to mono, but with a bigger
1307 factor for the left channel:
1309 pan=1:c0=0.9*c0+0.1*c1
1312 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1313 7-channels surround:
1315 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1318 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1319 that should be preferred (see "-ac" option) unless you have very specific
1322 @subsection Remapping examples
1324 The channel remapping will be effective if, and only if:
1327 @item gain coefficients are zeroes or ones,
1328 @item only one input per channel output,
1331 If all these conditions are satisfied, the filter will notify the user ("Pure
1332 channel mapping detected"), and use an optimized and lossless method to do the
1335 For example, if you have a 5.1 source and want a stereo audio stream by
1336 dropping the extra channels:
1338 pan="stereo: c0=FL : c1=FR"
1341 Given the same source, you can also switch front left and front right channels
1342 and keep the input channel layout:
1344 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1347 If the input is a stereo audio stream, you can mute the front left channel (and
1348 still keep the stereo channel layout) with:
1353 Still with a stereo audio stream input, you can copy the right channel in both
1354 front left and right:
1356 pan="stereo: c0=FR : c1=FR"
1361 Convert the audio sample format, sample rate and channel layout. This filter is
1362 not meant to be used directly.
1364 @section silencedetect
1366 Detect silence in an audio stream.
1368 This filter logs a message when it detects that the input audio volume is less
1369 or equal to a noise tolerance value for a duration greater or equal to the
1370 minimum detected noise duration.
1372 The printed times and duration are expressed in seconds.
1374 The filter accepts the following options:
1378 Set silence duration until notification (default is 2 seconds).
1381 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1382 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1385 @subsection Examples
1389 Detect 5 seconds of silence with -50dB noise tolerance:
1391 silencedetect=n=-50dB:d=5
1395 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1396 tolerance in @file{silence.mp3}:
1398 ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
1404 Boost or cut treble (upper) frequencies of the audio using a two-pole
1405 shelving filter with a response similar to that of a standard
1406 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
1408 The filter accepts the following options:
1412 Give the gain at whichever is the lower of ~22 kHz and the
1413 Nyquist frequency. Its useful range is about -20 (for a large cut)
1414 to +20 (for a large boost). Beware of clipping when using a positive gain.
1417 Set the filter's central frequency and so can be used
1418 to extend or reduce the frequency range to be boosted or cut.
1419 The default value is @code{3000} Hz.
1422 Set method to specify band-width of filter.
1435 Determine how steep is the filter's shelf transition.
1440 Adjust the input audio volume.
1442 The filter accepts the following options:
1447 Expresses how the audio volume will be increased or decreased.
1449 Output values are clipped to the maximum value.
1451 The output audio volume is given by the relation:
1453 @var{output_volume} = @var{volume} * @var{input_volume}
1456 Default value for @var{volume} is 1.0.
1459 Set the mathematical precision.
1461 This determines which input sample formats will be allowed, which affects the
1462 precision of the volume scaling.
1466 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1468 32-bit floating-point; limits input sample format to FLT. (default)
1470 64-bit floating-point; limits input sample format to DBL.
1474 @subsection Examples
1478 Halve the input audio volume:
1482 volume=volume=-6.0206dB
1485 In all the above example the named key for @option{volume} can be
1486 omitted, for example like in:
1492 Increase input audio power by 6 decibels using fixed-point precision:
1494 volume=volume=6dB:precision=fixed
1498 @section volumedetect
1500 Detect the volume of the input video.
1502 The filter has no parameters. The input is not modified. Statistics about
1503 the volume will be printed in the log when the input stream end is reached.
1505 In particular it will show the mean volume (root mean square), maximum
1506 volume (on a per-sample basis), and the beginning of an histogram of the
1507 registered volume values (from the maximum value to a cumulated 1/1000 of
1510 All volumes are in decibels relative to the maximum PCM value.
1512 @subsection Examples
1514 Here is an excerpt of the output:
1516 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1517 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1518 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1519 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1520 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1521 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1522 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1523 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1524 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1530 The mean square energy is approximately -27 dB, or 10^-2.7.
1532 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1534 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1537 In other words, raising the volume by +4 dB does not cause any clipping,
1538 raising it by +5 dB causes clipping for 6 samples, etc.
1540 @c man end AUDIO FILTERS
1542 @chapter Audio Sources
1543 @c man begin AUDIO SOURCES
1545 Below is a description of the currently available audio sources.
1549 Buffer audio frames, and make them available to the filter chain.
1551 This source is mainly intended for a programmatic use, in particular
1552 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1554 It accepts the following named parameters:
1559 Timebase which will be used for timestamps of submitted frames. It must be
1560 either a floating-point number or in @var{numerator}/@var{denominator} form.
1563 The sample rate of the incoming audio buffers.
1566 The sample format of the incoming audio buffers.
1567 Either a sample format name or its corresponging integer representation from
1568 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1570 @item channel_layout
1571 The channel layout of the incoming audio buffers.
1572 Either a channel layout name from channel_layout_map in
1573 @file{libavutil/channel_layout.c} or its corresponding integer representation
1574 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1577 The number of channels of the incoming audio buffers.
1578 If both @var{channels} and @var{channel_layout} are specified, then they
1583 @subsection Examples
1586 abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
1589 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1590 Since the sample format with name "s16p" corresponds to the number
1591 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1594 abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
1599 Generate an audio signal specified by an expression.
1601 This source accepts in input one or more expressions (one for each
1602 channel), which are evaluated and used to generate a corresponding
1605 This source accepts the following options:
1609 Set the '|'-separated expressions list for each separate channel. In case the
1610 @option{channel_layout} option is not specified, the selected channel layout
1611 depends on the number of provided expressions.
1613 @item channel_layout, c
1614 Set the channel layout. The number of channels in the specified layout
1615 must be equal to the number of specified expressions.
1618 Set the minimum duration of the sourced audio. See the function
1619 @code{av_parse_time()} for the accepted format.
1620 Note that the resulting duration may be greater than the specified
1621 duration, as the generated audio is always cut at the end of a
1624 If not specified, or the expressed duration is negative, the audio is
1625 supposed to be generated forever.
1628 Set the number of samples per channel per each output frame,
1631 @item sample_rate, s
1632 Specify the sample rate, default to 44100.
1635 Each expression in @var{exprs} can contain the following constants:
1639 number of the evaluated sample, starting from 0
1642 time of the evaluated sample expressed in seconds, starting from 0
1649 @subsection Examples
1659 Generate a sin signal with frequency of 440 Hz, set sample rate to
1662 aevalsrc="sin(440*2*PI*t):s=8000"
1666 Generate a two channels signal, specify the channel layout (Front
1667 Center + Back Center) explicitly:
1669 aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
1673 Generate white noise:
1675 aevalsrc="-2+random(0)"
1679 Generate an amplitude modulated signal:
1681 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1685 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1687 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
1694 Null audio source, return unprocessed audio frames. It is mainly useful
1695 as a template and to be employed in analysis / debugging tools, or as
1696 the source for filters which ignore the input data (for example the sox
1699 This source accepts the following options:
1703 @item channel_layout, cl
1705 Specify the channel layout, and can be either an integer or a string
1706 representing a channel layout. The default value of @var{channel_layout}
1709 Check the channel_layout_map definition in
1710 @file{libavutil/channel_layout.c} for the mapping between strings and
1711 channel layout values.
1713 @item sample_rate, r
1714 Specify the sample rate, and defaults to 44100.
1717 Set the number of samples per requested frames.
1721 @subsection Examples
1725 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1727 anullsrc=r=48000:cl=4
1731 Do the same operation with a more obvious syntax:
1733 anullsrc=r=48000:cl=mono
1737 All the parameters need to be explicitly defined.
1741 Synthesize a voice utterance using the libflite library.
1743 To enable compilation of this filter you need to configure FFmpeg with
1744 @code{--enable-libflite}.
1746 Note that the flite library is not thread-safe.
1748 The filter accepts the following options:
1753 If set to 1, list the names of the available voices and exit
1754 immediately. Default value is 0.
1757 Set the maximum number of samples per frame. Default value is 512.
1760 Set the filename containing the text to speak.
1763 Set the text to speak.
1766 Set the voice to use for the speech synthesis. Default value is
1767 @code{kal}. See also the @var{list_voices} option.
1770 @subsection Examples
1774 Read from file @file{speech.txt}, and synthetize the text using the
1775 standard flite voice:
1777 flite=textfile=speech.txt
1781 Read the specified text selecting the @code{slt} voice:
1783 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1787 Input text to ffmpeg:
1789 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1793 Make @file{ffplay} speak the specified text, using @code{flite} and
1794 the @code{lavfi} device:
1796 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1800 For more information about libflite, check:
1801 @url{http://www.speech.cs.cmu.edu/flite/}
1805 Generate an audio signal made of a sine wave with amplitude 1/8.
1807 The audio signal is bit-exact.
1809 The filter accepts the following options:
1814 Set the carrier frequency. Default is 440 Hz.
1816 @item beep_factor, b
1817 Enable a periodic beep every second with frequency @var{beep_factor} times
1818 the carrier frequency. Default is 0, meaning the beep is disabled.
1820 @item sample_rate, s
1821 Specify the sample rate, default is 44100.
1824 Specify the duration of the generated audio stream.
1826 @item samples_per_frame
1827 Set the number of samples per output frame, default is 1024.
1830 @subsection Examples
1835 Generate a simple 440 Hz sine wave:
1841 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
1845 sine=frequency=220:beep_factor=4:duration=5
1850 @c man end AUDIO SOURCES
1852 @chapter Audio Sinks
1853 @c man begin AUDIO SINKS
1855 Below is a description of the currently available audio sinks.
1857 @section abuffersink
1859 Buffer audio frames, and make them available to the end of filter chain.
1861 This sink is mainly intended for programmatic use, in particular
1862 through the interface defined in @file{libavfilter/buffersink.h}
1863 or the options system.
1865 It accepts a pointer to an AVABufferSinkContext structure, which
1866 defines the incoming buffers' formats, to be passed as the opaque
1867 parameter to @code{avfilter_init_filter} for initialization.
1871 Null audio sink, do absolutely nothing with the input audio. It is
1872 mainly useful as a template and to be employed in analysis / debugging
1875 @c man end AUDIO SINKS
1877 @chapter Video Filters
1878 @c man begin VIDEO FILTERS
1880 When you configure your FFmpeg build, you can disable any of the
1881 existing filters using @code{--disable-filters}.
1882 The configure output will show the video filters included in your
1885 Below is a description of the currently available video filters.
1887 @section alphaextract
1889 Extract the alpha component from the input as a grayscale video. This
1890 is especially useful with the @var{alphamerge} filter.
1894 Add or replace the alpha component of the primary input with the
1895 grayscale value of a second input. This is intended for use with
1896 @var{alphaextract} to allow the transmission or storage of frame
1897 sequences that have alpha in a format that doesn't support an alpha
1900 For example, to reconstruct full frames from a normal YUV-encoded video
1901 and a separate video created with @var{alphaextract}, you might use:
1903 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1906 Since this filter is designed for reconstruction, it operates on frame
1907 sequences without considering timestamps, and terminates when either
1908 input reaches end of stream. This will cause problems if your encoding
1909 pipeline drops frames. If you're trying to apply an image as an
1910 overlay to a video stream, consider the @var{overlay} filter instead.
1914 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1915 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1916 Substation Alpha) subtitles files.
1920 Compute the bounding box for the non-black pixels in the input frame
1923 This filter computes the bounding box containing all the pixels with a
1924 luminance value greater than the minimum allowed value.
1925 The parameters describing the bounding box are printed on the filter
1928 The filter accepts the following option:
1932 Set the minimal luminance value. Default is @code{16}.
1935 @section blackdetect
1937 Detect video intervals that are (almost) completely black. Can be
1938 useful to detect chapter transitions, commercials, or invalid
1939 recordings. Output lines contains the time for the start, end and
1940 duration of the detected black interval expressed in seconds.
1942 In order to display the output lines, you need to set the loglevel at
1943 least to the AV_LOG_INFO value.
1945 The filter accepts the following options:
1948 @item black_min_duration, d
1949 Set the minimum detected black duration expressed in seconds. It must
1950 be a non-negative floating point number.
1952 Default value is 2.0.
1954 @item picture_black_ratio_th, pic_th
1955 Set the threshold for considering a picture "black".
1956 Express the minimum value for the ratio:
1958 @var{nb_black_pixels} / @var{nb_pixels}
1961 for which a picture is considered black.
1962 Default value is 0.98.
1964 @item pixel_black_th, pix_th
1965 Set the threshold for considering a pixel "black".
1967 The threshold expresses the maximum pixel luminance value for which a
1968 pixel is considered "black". The provided value is scaled according to
1969 the following equation:
1971 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1974 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1975 the input video format, the range is [0-255] for YUV full-range
1976 formats and [16-235] for YUV non full-range formats.
1978 Default value is 0.10.
1981 The following example sets the maximum pixel threshold to the minimum
1982 value, and detects only black intervals of 2 or more seconds:
1984 blackdetect=d=2:pix_th=0.00
1989 Detect frames that are (almost) completely black. Can be useful to
1990 detect chapter transitions or commercials. Output lines consist of
1991 the frame number of the detected frame, the percentage of blackness,
1992 the position in the file if known or -1 and the timestamp in seconds.
1994 In order to display the output lines, you need to set the loglevel at
1995 least to the AV_LOG_INFO value.
1997 The filter accepts the following options:
2002 Set the percentage of the pixels that have to be below the threshold, defaults
2005 @item threshold, thresh
2006 Set the threshold below which a pixel value is considered black, defaults to
2013 Blend two video frames into each other.
2015 It takes two input streams and outputs one stream, the first input is the
2016 "top" layer and second input is "bottom" layer.
2017 Output terminates when shortest input terminates.
2019 A description of the accepted options follows.
2027 Set blend mode for specific pixel component or all pixel components in case
2028 of @var{all_mode}. Default value is @code{normal}.
2030 Available values for component modes are:
2063 Set blend opacity for specific pixel component or all pixel components in case
2064 of @var{all_opacity}. Only used in combination with pixel component blend modes.
2071 Set blend expression for specific pixel component or all pixel components in case
2072 of @var{all_expr}. Note that related mode options will be ignored if those are set.
2074 The expressions can use the following variables:
2078 The sequential number of the filtered frame, starting from @code{0}.
2082 the coordinates of the current sample
2086 the width and height of currently filtered plane
2090 Width and height scale depending on the currently filtered plane. It is the
2091 ratio between the corresponding luma plane number of pixels and the current
2092 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2093 @code{0.5,0.5} for chroma planes.
2096 Time of the current frame, expressed in seconds.
2099 Value of pixel component at current location for first video frame (top layer).
2102 Value of pixel component at current location for second video frame (bottom layer).
2106 @subsection Examples
2110 Apply transition from bottom layer to top layer in first 10 seconds:
2112 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
2116 Apply 1x1 checkerboard effect:
2118 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
2124 Apply boxblur algorithm to the input video.
2126 The filter accepts the following options:
2130 @item luma_radius, lr
2131 @item luma_power, lp
2132 @item chroma_radius, cr
2133 @item chroma_power, cp
2134 @item alpha_radius, ar
2135 @item alpha_power, ap
2139 A description of the accepted options follows.
2142 @item luma_radius, lr
2143 @item chroma_radius, cr
2144 @item alpha_radius, ar
2145 Set an expression for the box radius in pixels used for blurring the
2146 corresponding input plane.
2148 The radius value must be a non-negative number, and must not be
2149 greater than the value of the expression @code{min(w,h)/2} for the
2150 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2153 Default value for @option{luma_radius} is "2". If not specified,
2154 @option{chroma_radius} and @option{alpha_radius} default to the
2155 corresponding value set for @option{luma_radius}.
2157 The expressions can contain the following constants:
2161 the input width and height in pixels
2165 the input chroma image width and height in pixels
2169 horizontal and vertical chroma subsample values. For example for the
2170 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2173 @item luma_power, lp
2174 @item chroma_power, cp
2175 @item alpha_power, ap
2176 Specify how many times the boxblur filter is applied to the
2177 corresponding plane.
2179 Default value for @option{luma_power} is 2. If not specified,
2180 @option{chroma_power} and @option{alpha_power} default to the
2181 corresponding value set for @option{luma_power}.
2183 A value of 0 will disable the effect.
2186 @subsection Examples
2190 Apply a boxblur filter with luma, chroma, and alpha radius
2193 boxblur=luma_radius=2:luma_power=1
2198 Set luma radius to 2, alpha and chroma radius to 0:
2200 boxblur=2:1:cr=0:ar=0
2204 Set luma and chroma radius to a fraction of the video dimension:
2206 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
2210 @section colorbalance
2211 Modify intensity of primary colors (red, green and blue) of input frames.
2213 The filter allows an input frame to be adjusted in the shadows, midtones or highlights
2214 regions for the red-cyan, green-magenta or blue-yellow balance.
2216 A positive adjustment value shifts the balance towards the primary color, a negative
2217 value towards the complementary color.
2219 The filter accepts the following options:
2225 Adjust red, green and blue shadows (darkest pixels).
2230 Adjust red, green and blue midtones (medium pixels).
2235 Adjust red, green and blue highlights (brightest pixels).
2237 Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}.
2240 @subsection Examples
2244 Add red color cast to shadows:
2250 @section colorchannelmixer
2252 Adjust video input frames by re-mixing color channels.
2254 This filter modifies a color channel by adding the values associated to
2255 the other channels of the same pixels. For example if the value to
2256 modify is red, the output value will be:
2258 @var{red}=@var{red}*@var{rr} + @var{blue}*@var{rb} + @var{green}*@var{rg} + @var{alpha}*@var{ra}
2261 The filter accepts the following options:
2268 Adjust contribution of input red, green, blue and alpha channels for output red channel.
2269 Default is @code{1} for @var{rr}, and @code{0} for @var{rg}, @var{rb} and @var{ra}.
2275 Adjust contribution of input red, green, blue and alpha channels for output green channel.
2276 Default is @code{1} for @var{gg}, and @code{0} for @var{gr}, @var{gb} and @var{ga}.
2282 Adjust contribution of input red, green, blue and alpha channels for output blue channel.
2283 Default is @code{1} for @var{bb}, and @code{0} for @var{br}, @var{bg} and @var{ba}.
2289 Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
2290 Default is @code{1} for @var{aa}, and @code{0} for @var{ar}, @var{ag} and @var{ab}.
2292 Allowed ranges for options are @code{[-2.0, 2.0]}.
2295 @subsection Examples
2299 Convert source to grayscale:
2301 colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
2305 @section colormatrix
2307 Convert color matrix.
2309 The filter accepts the following options:
2314 Specify the source and destination color matrix. Both values must be
2317 The accepted values are:
2333 For example to convert from BT.601 to SMPTE-240M, use the command:
2335 colormatrix=bt601:smpte240m
2340 Copy the input source unchanged to the output. Mainly useful for
2345 Crop the input video to given dimensions.
2347 The filter accepts the following options:
2351 Width of the output video. It defaults to @code{iw}.
2352 This expression is evaluated only once during the filter
2356 Height of the output video. It defaults to @code{ih}.
2357 This expression is evaluated only once during the filter
2361 Horizontal position, in the input video, of the left edge of the output video.
2362 It defaults to @code{(in_w-out_w)/2}.
2363 This expression is evaluated per-frame.
2366 Vertical position, in the input video, of the top edge of the output video.
2367 It defaults to @code{(in_h-out_h)/2}.
2368 This expression is evaluated per-frame.
2371 If set to 1 will force the output display aspect ratio
2372 to be the same of the input, by changing the output sample aspect
2373 ratio. It defaults to 0.
2376 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2377 expressions containing the following constants:
2382 the computed values for @var{x} and @var{y}. They are evaluated for
2387 the input width and height
2391 same as @var{in_w} and @var{in_h}
2395 the output (cropped) width and height
2399 same as @var{out_w} and @var{out_h}
2402 same as @var{iw} / @var{ih}
2405 input sample aspect ratio
2408 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2412 horizontal and vertical chroma subsample values. For example for the
2413 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2416 the number of input frame, starting from 0
2419 the position in the file of the input frame, NAN if unknown
2422 timestamp expressed in seconds, NAN if the input timestamp is unknown
2426 The expression for @var{out_w} may depend on the value of @var{out_h},
2427 and the expression for @var{out_h} may depend on @var{out_w}, but they
2428 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2429 evaluated after @var{out_w} and @var{out_h}.
2431 The @var{x} and @var{y} parameters specify the expressions for the
2432 position of the top-left corner of the output (non-cropped) area. They
2433 are evaluated for each frame. If the evaluated value is not valid, it
2434 is approximated to the nearest valid value.
2436 The expression for @var{x} may depend on @var{y}, and the expression
2437 for @var{y} may depend on @var{x}.
2439 @subsection Examples
2443 Crop area with size 100x100 at position (12,34).
2448 Using named options, the example above becomes:
2450 crop=w=100:h=100:x=12:y=34
2454 Crop the central input area with size 100x100:
2460 Crop the central input area with size 2/3 of the input video:
2462 crop=2/3*in_w:2/3*in_h
2466 Crop the input video central square:
2473 Delimit the rectangle with the top-left corner placed at position
2474 100:100 and the right-bottom corner corresponding to the right-bottom
2475 corner of the input image:
2477 crop=in_w-100:in_h-100:100:100
2481 Crop 10 pixels from the left and right borders, and 20 pixels from
2482 the top and bottom borders
2484 crop=in_w-2*10:in_h-2*20
2488 Keep only the bottom right quarter of the input image:
2490 crop=in_w/2:in_h/2:in_w/2:in_h/2
2494 Crop height for getting Greek harmony:
2496 crop=in_w:1/PHI*in_w
2500 Appply trembling effect:
2502 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)
2506 Apply erratic camera effect depending on timestamp:
2508 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)"
2512 Set x depending on the value of y:
2514 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2520 Auto-detect crop size.
2522 Calculate necessary cropping parameters and prints the recommended
2523 parameters through the logging system. The detected dimensions
2524 correspond to the non-black area of the input video.
2526 The filter accepts the following options:
2531 Set higher black value threshold, which can be optionally specified
2532 from nothing (0) to everything (255). An intensity value greater
2533 to the set value is considered non-black. Default value is 24.
2536 Set the value for which the width/height should be divisible by. The
2537 offset is automatically adjusted to center the video. Use 2 to get
2538 only even dimensions (needed for 4:2:2 video). 16 is best when
2539 encoding to most video codecs. Default value is 16.
2541 @item reset_count, reset
2542 Set the counter that determines after how many frames cropdetect will
2543 reset the previously detected largest video area and start over to
2544 detect the current optimal crop area. Default value is 0.
2546 This can be useful when channel logos distort the video area. 0
2547 indicates never reset and return the largest area encountered during
2554 Apply color adjustments using curves.
2556 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
2557 component (red, green and blue) has its values defined by @var{N} key points
2558 tied from each other using a smooth curve. The x-axis represents the pixel
2559 values from the input frame, and the y-axis the new pixel values to be set for
2562 By default, a component curve is defined by the two points @var{(0;0)} and
2563 @var{(1;1)}. This creates a straight line where each original pixel value is
2564 "adjusted" to its own value, which means no change to the image.
2566 The filter allows you to redefine these two points and add some more. A new
2567 curve (using a natural cubic spline interpolation) will be define to pass
2568 smoothly through all these new coordinates. The new defined points needs to be
2569 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
2570 be in the @var{[0;1]} interval. If the computed curves happened to go outside
2571 the vector spaces, the values will be clipped accordingly.
2573 If there is no key point defined in @code{x=0}, the filter will automatically
2574 insert a @var{(0;0)} point. In the same way, if there is no key point defined
2575 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
2577 The filter accepts the following options:
2581 Select one of the available color presets. This option can be used in addition
2582 to the @option{r}, @option{g}, @option{b} parameters; in this case, the later
2583 options takes priority on the preset values.
2584 Available presets are:
2587 @item color_negative
2590 @item increase_contrast
2592 @item linear_contrast
2593 @item medium_contrast
2595 @item strong_contrast
2598 Default is @code{none}.
2600 Set the master key points. These points will define a second pass mapping. It
2601 is sometimes called a "luminance" or "value" mapping. It can be used with
2602 @option{r}, @option{g}, @option{b} or @option{all} since it acts like a
2603 post-processing LUT.
2605 Set the key points for the red component.
2607 Set the key points for the green component.
2609 Set the key points for the blue component.
2611 Set the key points for all components (not including master).
2612 Can be used in addition to the other key points component
2613 options. In this case, the unset component(s) will fallback on this
2614 @option{all} setting.
2616 Specify a Photoshop curves file (@code{.asv}) to import the settings from.
2619 To avoid some filtergraph syntax conflicts, each key points list need to be
2620 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
2622 @subsection Examples
2626 Increase slightly the middle level of blue:
2628 curves=blue='0.5/0.58'
2634 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
2636 Here we obtain the following coordinates for each components:
2639 @code{(0;0.11) (0.42;0.51) (1;0.95)}
2641 @code{(0;0) (0.50;0.48) (1;1)}
2643 @code{(0;0.22) (0.49;0.44) (1;0.80)}
2647 The previous example can also be achieved with the associated built-in preset:
2649 curves=preset=vintage
2659 Use a Photoshop preset and redefine the points of the green component:
2661 curves=psfile='MyCurvesPresets/purple.asv':green='0.45/0.53'
2667 Denoise frames using 2D DCT (frequency domain filtering).
2669 This filter is not designed for real time and can be extremely slow.
2671 The filter accepts the following options:
2675 Set the noise sigma constant.
2677 This @var{sigma} defines a hard threshold of @code{3 * sigma}; every DCT
2678 coefficient (absolute value) below this threshold with be dropped.
2680 If you need a more advanced filtering, see @option{expr}.
2682 Default is @code{0}.
2685 Set number overlapping pixels for each block. Each block is of size
2686 @code{16x16}. Since the filter can be slow, you may want to reduce this value,
2687 at the cost of a less effective filter and the risk of various artefacts.
2689 If the overlapping value doesn't allow to process the whole input width or
2690 height, a warning will be displayed and according borders won't be denoised.
2692 Default value is @code{15}.
2695 Set the coefficient factor expression.
2697 For each coefficient of a DCT block, this expression will be evaluated as a
2698 multiplier value for the coefficient.
2700 If this is option is set, the @option{sigma} option will be ignored.
2702 The absolute value of the coefficient can be accessed through the @var{c}
2706 @subsection Examples
2708 Apply a denoise with a @option{sigma} of @code{4.5}:
2713 The same operation can be achieved using the expression system:
2715 dctdnoiz=e='gte(c, 4.5*3)'
2721 Drop duplicated frames at regular intervals.
2723 The filter accepts the following options:
2727 Set the number of frames from which one will be dropped. Setting this to
2728 @var{N} means one frame in every batch of @var{N} frames will be dropped.
2729 Default is @code{5}.
2732 Set the threshold for duplicate detection. If the difference metric for a frame
2733 is less than or equal to this value, then it is declared as duplicate. Default
2737 Set scene change threshold. Default is @code{15}.
2741 Set the size of the x and y-axis blocks used during metric calculations.
2742 Larger blocks give better noise suppression, but also give worse detection of
2743 small movements. Must be a power of two. Default is @code{32}.
2746 Mark main input as a pre-processed input and activate clean source input
2747 stream. This allows the input to be pre-processed with various filters to help
2748 the metrics calculation while keeping the frame selection lossless. When set to
2749 @code{1}, the first stream is for the pre-processed input, and the second
2750 stream is the clean source from where the kept frames are chosen. Default is
2754 Set whether or not chroma is considered in the metric calculations. Default is
2760 Suppress a TV station logo by a simple interpolation of the surrounding
2761 pixels. Just set a rectangle covering the logo and watch it disappear
2762 (and sometimes something even uglier appear - your mileage may vary).
2764 This filter accepts the following options:
2769 Specify the top left corner coordinates of the logo. They must be
2774 Specify the width and height of the logo to clear. They must be
2778 Specify the thickness of the fuzzy edge of the rectangle (added to
2779 @var{w} and @var{h}). The default value is 4.
2782 When set to 1, a green rectangle is drawn on the screen to simplify
2783 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2784 @var{band} is set to 4. The default value is 0.
2788 @subsection Examples
2792 Set a rectangle covering the area with top left corner coordinates 0,0
2793 and size 100x77, setting a band of size 10:
2795 delogo=x=0:y=0:w=100:h=77:band=10
2802 Attempt to fix small changes in horizontal and/or vertical shift. This
2803 filter helps remove camera shake from hand-holding a camera, bumping a
2804 tripod, moving on a vehicle, etc.
2806 The filter accepts the following options:
2814 Specify a rectangular area where to limit the search for motion
2816 If desired the search for motion vectors can be limited to a
2817 rectangular area of the frame defined by its top left corner, width
2818 and height. These parameters have the same meaning as the drawbox
2819 filter which can be used to visualise the position of the bounding
2822 This is useful when simultaneous movement of subjects within the frame
2823 might be confused for camera motion by the motion vector search.
2825 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2826 then the full frame is used. This allows later options to be set
2827 without specifying the bounding box for the motion vector search.
2829 Default - search the whole frame.
2833 Specify the maximum extent of movement in x and y directions in the
2834 range 0-64 pixels. Default 16.
2837 Specify how to generate pixels to fill blanks at the edge of the
2838 frame. Available values are:
2841 Fill zeroes at blank locations
2843 Original image at blank locations
2845 Extruded edge value at blank locations
2847 Mirrored edge at blank locations
2849 Default value is @samp{mirror}.
2852 Specify the blocksize to use for motion search. Range 4-128 pixels,
2856 Specify the contrast threshold for blocks. Only blocks with more than
2857 the specified contrast (difference between darkest and lightest
2858 pixels) will be considered. Range 1-255, default 125.
2861 Specify the search strategy. Available values are:
2864 Set exhaustive search
2866 Set less exhaustive search.
2868 Default value is @samp{exhaustive}.
2871 If set then a detailed log of the motion search is written to the
2875 If set to 1, specify using OpenCL capabilities, only available if
2876 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
2882 Draw a colored box on the input image.
2884 This filter accepts the following options:
2889 Specify the top left corner coordinates of the box. Default to 0.
2893 Specify the width and height of the box, if 0 they are interpreted as
2894 the input width and height. Default to 0.
2897 Specify the color of the box to write, it can be the name of a color
2898 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2899 value @code{invert} is used, the box edge color is the same as the
2900 video with inverted luma.
2903 Set the thickness of the box edge. Default value is @code{3}.
2906 @subsection Examples
2910 Draw a black box around the edge of the input image:
2916 Draw a box with color red and an opacity of 50%:
2918 drawbox=10:20:200:60:red@@0.5
2921 The previous example can be specified as:
2923 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2927 Fill the box with pink color:
2929 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2935 Draw a grid on the input image.
2937 This filter accepts the following options:
2942 Specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
2946 Specify the width and height of the grid cell, if 0 they are interpreted as the
2947 input width and height, respectively, minus @code{thickness}, so image gets
2948 framed. Default to 0.
2951 Specify the color of the grid, it can be the name of a color
2952 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2953 value @code{invert} is used, the grid color is the same as the
2954 video with inverted luma.
2955 Note that you can append opacity value (in range of 0.0 - 1.0)
2956 to color name after @@ sign.
2959 Set the thickness of the grid line. Default value is @code{1}.
2962 @subsection Examples
2966 Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%:
2968 drawgrid=width=100:height=100:thickness=2:color=red@@0.5
2975 Draw text string or text from specified file on top of video using the
2976 libfreetype library.
2978 To enable compilation of this filter you need to configure FFmpeg with
2979 @code{--enable-libfreetype}.
2983 The description of the accepted parameters follows.
2988 Used to draw a box around text using background color.
2989 Value should be either 1 (enable) or 0 (disable).
2990 The default value of @var{box} is 0.
2993 The color to be used for drawing box around text.
2994 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2995 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2996 The default value of @var{boxcolor} is "white".
2999 Set an expression which specifies if the text should be drawn. If the
3000 expression evaluates to 0, the text is not drawn. This is useful for
3001 specifying that the text should be drawn only when specific conditions
3004 Default value is "1".
3006 See below for the list of accepted constants and functions.
3009 Select how the @var{text} is expanded. Can be either @code{none},
3010 @code{strftime} (deprecated) or
3011 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
3015 If true, check and fix text coords to avoid clipping.
3018 The color to be used for drawing fonts.
3019 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
3020 (e.g. "0xff000033"), possibly followed by an alpha specifier.
3021 The default value of @var{fontcolor} is "black".
3024 The font file to be used for drawing text. Path must be included.
3025 This parameter is mandatory.
3028 The font size to be used for drawing text.
3029 The default value of @var{fontsize} is 16.
3032 Flags to be used for loading the fonts.
3034 The flags map the corresponding flags supported by libfreetype, and are
3035 a combination of the following values:
3042 @item vertical_layout
3043 @item force_autohint
3046 @item ignore_global_advance_width
3048 @item ignore_transform
3054 Default value is "render".
3056 For more information consult the documentation for the FT_LOAD_*
3060 The color to be used for drawing a shadow behind the drawn text. It
3061 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
3062 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
3063 The default value of @var{shadowcolor} is "black".
3067 The x and y offsets for the text shadow position with respect to the
3068 position of the text. They can be either positive or negative
3069 values. Default value for both is "0".
3072 The starting frame number for the n/frame_num variable. The default value
3076 The size in number of spaces to use for rendering the tab.
3080 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
3081 format. It can be used with or without text parameter. @var{timecode_rate}
3082 option must be specified.
3084 @item timecode_rate, rate, r
3085 Set the timecode frame rate (timecode only).
3088 The text string to be drawn. The text must be a sequence of UTF-8
3090 This parameter is mandatory if no file is specified with the parameter
3094 A text file containing text to be drawn. The text must be a sequence
3095 of UTF-8 encoded characters.
3097 This parameter is mandatory if no text string is specified with the
3098 parameter @var{text}.
3100 If both @var{text} and @var{textfile} are specified, an error is thrown.
3103 If set to 1, the @var{textfile} will be reloaded before each frame.
3104 Be sure to update it atomically, or it may be read partially, or even fail.
3108 The expressions which specify the offsets where text will be drawn
3109 within the video frame. They are relative to the top/left border of the
3112 The default value of @var{x} and @var{y} is "0".
3114 See below for the list of accepted constants and functions.
3117 The parameters for @var{x} and @var{y} are expressions containing the
3118 following constants and functions:
3122 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
3126 horizontal and vertical chroma subsample values. For example for the
3127 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3130 the height of each text line
3138 @item max_glyph_a, ascent
3139 the maximum distance from the baseline to the highest/upper grid
3140 coordinate used to place a glyph outline point, for all the rendered
3142 It is a positive value, due to the grid's orientation with the Y axis
3145 @item max_glyph_d, descent
3146 the maximum distance from the baseline to the lowest grid coordinate
3147 used to place a glyph outline point, for all the rendered glyphs.
3148 This is a negative value, due to the grid's orientation, with the Y axis
3152 maximum glyph height, that is the maximum height for all the glyphs
3153 contained in the rendered text, it is equivalent to @var{ascent} -
3157 maximum glyph width, that is the maximum width for all the glyphs
3158 contained in the rendered text
3161 the number of input frame, starting from 0
3163 @item rand(min, max)
3164 return a random number included between @var{min} and @var{max}
3167 input sample aspect ratio
3170 timestamp expressed in seconds, NAN if the input timestamp is unknown
3173 the height of the rendered text
3176 the width of the rendered text
3180 the x and y offset coordinates where the text is drawn.
3182 These parameters allow the @var{x} and @var{y} expressions to refer
3183 each other, so you can for example specify @code{y=x/dar}.
3186 If libavfilter was built with @code{--enable-fontconfig}, then
3187 @option{fontfile} can be a fontconfig pattern or omitted.
3189 @anchor{drawtext_expansion}
3190 @subsection Text expansion
3192 If @option{expansion} is set to @code{strftime},
3193 the filter recognizes strftime() sequences in the provided text and
3194 expands them accordingly. Check the documentation of strftime(). This
3195 feature is deprecated.
3197 If @option{expansion} is set to @code{none}, the text is printed verbatim.
3199 If @option{expansion} is set to @code{normal} (which is the default),
3200 the following expansion mechanism is used.
3202 The backslash character '\', followed by any character, always expands to
3203 the second character.
3205 Sequence of the form @code{%@{...@}} are expanded. The text between the
3206 braces is a function name, possibly followed by arguments separated by ':'.
3207 If the arguments contain special characters or delimiters (':' or '@}'),
3208 they should be escaped.
3210 Note that they probably must also be escaped as the value for the
3211 @option{text} option in the filter argument string and as the filter
3212 argument in the filtergraph description, and possibly also for the shell,
3213 that makes up to four levels of escaping; using a text file avoids these
3216 The following functions are available:
3221 The expression evaluation result.
3223 It must take one argument specifying the expression to be evaluated,
3224 which accepts the same constants and functions as the @var{x} and
3225 @var{y} values. Note that not all constants should be used, for
3226 example the text size is not known when evaluating the expression, so
3227 the constants @var{text_w} and @var{text_h} will have an undefined
3231 The time at which the filter is running, expressed in UTC.
3232 It can accept an argument: a strftime() format string.
3235 The time at which the filter is running, expressed in the local time zone.
3236 It can accept an argument: a strftime() format string.
3239 The frame number, starting from 0.
3242 A 1 character description of the current picture type.
3245 The timestamp of the current frame, in seconds, with microsecond accuracy.
3249 @subsection Examples
3253 Draw "Test Text" with font FreeSerif, using the default values for the
3254 optional parameters.
3257 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
3261 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
3262 and y=50 (counting from the top-left corner of the screen), text is
3263 yellow with a red box around it. Both the text and the box have an
3267 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
3268 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
3271 Note that the double quotes are not necessary if spaces are not used
3272 within the parameter list.
3275 Show the text at the center of the video frame:
3277 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
3281 Show a text line sliding from right to left in the last row of the video
3282 frame. The file @file{LONG_LINE} is assumed to contain a single line
3285 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
3289 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
3291 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
3295 Draw a single green letter "g", at the center of the input video.
3296 The glyph baseline is placed at half screen height.
3298 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
3302 Show text for 1 second every 3 seconds:
3304 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
3308 Use fontconfig to set the font. Note that the colons need to be escaped.
3310 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
3314 Print the date of a real-time encoding (see strftime(3)):
3316 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
3321 For more information about libfreetype, check:
3322 @url{http://www.freetype.org/}.
3324 For more information about fontconfig, check:
3325 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3329 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3331 The filter accepts the following options:
3336 Set low and high threshold values used by the Canny thresholding
3339 The high threshold selects the "strong" edge pixels, which are then
3340 connected through 8-connectivity with the "weak" edge pixels selected
3341 by the low threshold.
3343 @var{low} and @var{high} threshold values must be choosen in the range
3344 [0,1], and @var{low} should be lesser or equal to @var{high}.
3346 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3352 edgedetect=low=0.1:high=0.4
3355 @section extractplanes
3357 Extract color channel components from input video stream into
3358 separate grayscale video streams.
3360 The filter accepts the following option:
3364 Set plane(s) to extract.
3366 Available values for planes are:
3377 Choosing planes not available in the input will result in an error.
3378 That means you cannot select @code{r}, @code{g}, @code{b} planes
3379 with @code{y}, @code{u}, @code{v} planes at same time.
3382 @subsection Examples
3386 Extract luma, u and v color channel component from input video frame
3387 into 3 grayscale outputs:
3389 ffmpeg -i video.avi -filter_complex 'extractplanes=y+u+v[y][u][v]' -map '[y]' y.avi -map '[u]' u.avi -map '[v]' v.avi
3395 Apply fade-in/out effect to input video.
3397 This filter accepts the following options:
3401 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3403 Default is @code{in}.
3405 @item start_frame, s
3406 Specify the number of the start frame for starting to apply the fade
3407 effect. Default is 0.
3410 The number of frames for which the fade effect has to last. At the end of the
3411 fade-in effect the output video will have the same intensity as the input video,
3412 at the end of the fade-out transition the output video will be completely black.
3416 If set to 1, fade only alpha channel, if one exists on the input.
3419 @item start_time, st
3420 Specify the timestamp (in seconds) of the frame to start to apply the fade
3421 effect. If both start_frame and start_time are specified, the fade will start at
3422 whichever comes last. Default is 0.
3425 The number of seconds for which the fade effect has to last. At the end of the
3426 fade-in effect the output video will have the same intensity as the input video,
3427 at the end of the fade-out transition the output video will be completely black.
3428 If both duration and nb_frames are specified, duration is used. Default is 0.
3431 @subsection Examples
3435 Fade in first 30 frames of video:
3440 The command above is equivalent to:
3446 Fade out last 45 frames of a 200-frame video:
3449 fade=type=out:start_frame=155:nb_frames=45
3453 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
3455 fade=in:0:25, fade=out:975:25
3459 Make first 5 frames black, then fade in from frame 5-24:
3465 Fade in alpha over first 25 frames of video:
3467 fade=in:0:25:alpha=1
3471 Make first 5.5 seconds black, then fade in for 0.5 seconds:
3473 fade=t=in:st=5.5:d=0.5
3480 Extract a single field from an interlaced image using stride
3481 arithmetic to avoid wasting CPU time. The output frames are marked as
3484 The filter accepts the following options:
3488 Specify whether to extract the top (if the value is @code{0} or
3489 @code{top}) or the bottom field (if the value is @code{1} or
3495 Field matching filter for inverse telecine. It is meant to reconstruct the
3496 progressive frames from a telecined stream. The filter does not drop duplicated
3497 frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be
3498 followed by a decimation filter such as @ref{decimate} in the filtergraph.
3500 The separation of the field matching and the decimation is notably motivated by
3501 the possibility of inserting a de-interlacing filter fallback between the two.
3502 If the source has mixed telecined and real interlaced content,
3503 @code{fieldmatch} will not be able to match fields for the interlaced parts.
3504 But these remaining combed frames will be marked as interlaced, and thus can be
3505 de-interlaced by a later filter such as @ref{yadif} before decimation.
3507 In addition to the various configuration options, @code{fieldmatch} can take an
3508 optional second stream, activated through the @option{ppsrc} option. If
3509 enabled, the frames reconstruction will be based on the fields and frames from
3510 this second stream. This allows the first input to be pre-processed in order to
3511 help the various algorithms of the filter, while keeping the output lossless
3512 (assuming the fields are matched properly). Typically, a field-aware denoiser,
3513 or brightness/contrast adjustments can help.
3515 Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
3516 and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
3517 which @code{fieldmatch} is based on. While the semantic and usage are very
3518 close, some behaviour and options names can differ.
3520 The filter accepts the following options:
3524 Specify the assumed field order of the input stream. Available values are:
3528 Auto detect parity (use FFmpeg's internal parity value).
3530 Assume bottom field first.
3532 Assume top field first.
3535 Note that it is sometimes recommended not to trust the parity announced by the
3538 Default value is @var{auto}.
3541 Set the matching mode or strategy to use. @option{pc} mode is the safest in the
3542 sense that it wont risk creating jerkiness due to duplicate frames when
3543 possible, but if there are bad edits or blended fields it will end up
3544 outputting combed frames when a good match might actually exist. On the other
3545 hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness,
3546 but will almost always find a good frame if there is one. The other values are
3547 all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking
3548 jerkiness and creating duplicate frames versus finding good matches in sections
3549 with bad edits, orphaned fields, blended fields, etc.
3551 More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section.
3553 Available values are:
3557 2-way matching (p/c)
3559 2-way matching, and trying 3rd match if still combed (p/c + n)
3561 2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
3563 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
3564 still combed (p/c + n + u/b)
3566 3-way matching (p/c/n)
3568 3-way matching, and trying 4th/5th matches if all 3 of the original matches are
3569 detected as combed (p/c/n + u/b)
3572 The parenthesis at the end indicate the matches that would be used for that
3573 mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or
3576 In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is
3579 Default value is @var{pc_n}.
3582 Mark the main input stream as a pre-processed input, and enable the secondary
3583 input stream as the clean source to pick the fields from. See the filter
3584 introduction for more details. It is similar to the @option{clip2} feature from
3587 Default value is @code{0} (disabled).
3590 Set the field to match from. It is recommended to set this to the same value as
3591 @option{order} unless you experience matching failures with that setting. In
3592 certain circumstances changing the field that is used to match from can have a
3593 large impact on matching performance. Available values are:
3597 Automatic (same value as @option{order}).
3599 Match from the bottom field.
3601 Match from the top field.
3604 Default value is @var{auto}.
3607 Set whether or not chroma is included during the match comparisons. In most
3608 cases it is recommended to leave this enabled. You should set this to @code{0}
3609 only if your clip has bad chroma problems such as heavy rainbowing or other
3610 artifacts. Setting this to @code{0} could also be used to speed things up at
3611 the cost of some accuracy.
3613 Default value is @code{1}.
3617 These define an exclusion band which excludes the lines between @option{y0} and
3618 @option{y1} from being included in the field matching decision. An exclusion
3619 band can be used to ignore subtitles, a logo, or other things that may
3620 interfere with the matching. @option{y0} sets the starting scan line and
3621 @option{y1} sets the ending line; all lines in between @option{y0} and
3622 @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting
3623 @option{y0} and @option{y1} to the same value will disable the feature.
3624 @option{y0} and @option{y1} defaults to @code{0}.
3627 Set the scene change detection threshold as a percentage of maximum change on
3628 the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change
3629 detection is only relevant in case @option{combmatch}=@var{sc}. The range for
3630 @option{scthresh} is @code{[0.0, 100.0]}.
3632 Default value is @code{12.0}.
3635 When @option{combatch} is not @var{none}, @code{fieldmatch} will take into
3636 account the combed scores of matches when deciding what match to use as the
3637 final match. Available values are:
3641 No final matching based on combed scores.
3643 Combed scores are only used when a scene change is detected.
3645 Use combed scores all the time.
3648 Default is @var{sc}.
3651 Force @code{fieldmatch} to calculate the combed metrics for certain matches and
3652 print them. This setting is known as @option{micout} in TFM/VFM vocabulary.
3653 Available values are:
3657 No forced calculation.
3659 Force p/c/n calculations.
3661 Force p/c/n/u/b calculations.
3664 Default value is @var{none}.
3667 This is the area combing threshold used for combed frame detection. This
3668 essentially controls how "strong" or "visible" combing must be to be detected.
3669 Larger values mean combing must be more visible and smaller values mean combing
3670 can be less visible or strong and still be detected. Valid settings are from
3671 @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will
3672 be detected as combed). This is basically a pixel difference value. A good
3673 range is @code{[8, 12]}.
3675 Default value is @code{9}.
3678 Sets whether or not chroma is considered in the combed frame decision. Only
3679 disable this if your source has chroma problems (rainbowing, etc.) that are
3680 causing problems for the combed frame detection with chroma enabled. Actually,
3681 using @option{chroma}=@var{0} is usually more reliable, except for the case
3682 where there is chroma only combing in the source.
3684 Default value is @code{0}.
3688 Respectively set the x-axis and y-axis size of the window used during combed
3689 frame detection. This has to do with the size of the area in which
3690 @option{combpel} pixels are required to be detected as combed for a frame to be
3691 declared combed. See the @option{combpel} parameter description for more info.
3692 Possible values are any number that is a power of 2 starting at 4 and going up
3695 Default value is @code{16}.
3698 The number of combed pixels inside any of the @option{blocky} by
3699 @option{blockx} size blocks on the frame for the frame to be detected as
3700 combed. While @option{cthresh} controls how "visible" the combing must be, this
3701 setting controls "how much" combing there must be in any localized area (a
3702 window defined by the @option{blockx} and @option{blocky} settings) on the
3703 frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at
3704 which point no frames will ever be detected as combed). This setting is known
3705 as @option{MI} in TFM/VFM vocabulary.
3707 Default value is @code{80}.
3710 @anchor{p/c/n/u/b meaning}
3711 @subsection p/c/n/u/b meaning
3713 @subsubsection p/c/n
3715 We assume the following telecined stream:
3718 Top fields: 1 2 2 3 4
3719 Bottom fields: 1 2 3 4 4
3722 The numbers correspond to the progressive frame the fields relate to. Here, the
3723 first two frames are progressive, the 3rd and 4th are combed, and so on.
3725 When @code{fieldmatch} is configured to run a matching from bottom
3726 (@option{field}=@var{bottom}) this is how this input stream get transformed:
3731 B 1 2 3 4 4 <-- matching reference
3740 As a result of the field matching, we can see that some frames get duplicated.
3741 To perform a complete inverse telecine, you need to rely on a decimation filter
3742 after this operation. See for instance the @ref{decimate} filter.
3744 The same operation now matching from top fields (@option{field}=@var{top})
3749 T 1 2 2 3 4 <-- matching reference
3759 In these examples, we can see what @var{p}, @var{c} and @var{n} mean;
3760 basically, they refer to the frame and field of the opposite parity:
3763 @item @var{p} matches the field of the opposite parity in the previous frame
3764 @item @var{c} matches the field of the opposite parity in the current frame
3765 @item @var{n} matches the field of the opposite parity in the next frame
3770 The @var{u} and @var{b} matching are a bit special in the sense that they match
3771 from the opposite parity flag. In the following examples, we assume that we are
3772 currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
3773 'x' is placed above and below each matched fields.
3775 With bottom matching (@option{field}=@var{bottom}):
3780 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
3781 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
3789 With top matching (@option{field}=@var{top}):
3794 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
3795 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
3803 @subsection Examples
3805 Simple IVTC of a top field first telecined stream:
3807 fieldmatch=order=tff:combmatch=none, decimate
3810 Advanced IVTC, with fallback on @ref{yadif} for still combed frames:
3812 fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
3817 Transform the field order of the input video.
3819 This filter accepts the following options:
3824 Output field order. Valid values are @var{tff} for top field first or @var{bff}
3825 for bottom field first.
3828 Default value is @samp{tff}.
3830 Transformation is achieved by shifting the picture content up or down
3831 by one line, and filling the remaining line with appropriate picture content.
3832 This method is consistent with most broadcast field order converters.
3834 If the input video is not flagged as being interlaced, or it is already
3835 flagged as being of the required output field order then this filter does
3836 not alter the incoming video.
3838 This filter is very useful when converting to or from PAL DV material,
3839 which is bottom field first.
3843 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
3848 Buffer input images and send them when they are requested.
3850 This filter is mainly useful when auto-inserted by the libavfilter
3853 The filter does not take parameters.
3858 Convert the input video to one of the specified pixel formats.
3859 Libavfilter will try to pick one that is supported for the input to
3862 This filter accepts the following parameters:
3866 A '|'-separated list of pixel format names, for example
3867 "pix_fmts=yuv420p|monow|rgb24".
3871 @subsection Examples
3875 Convert the input video to the format @var{yuv420p}
3877 format=pix_fmts=yuv420p
3880 Convert the input video to any of the formats in the list
3882 format=pix_fmts=yuv420p|yuv444p|yuv410p
3888 Convert the video to specified constant frame rate by duplicating or dropping
3889 frames as necessary.
3891 This filter accepts the following named parameters:
3895 Desired output frame rate. The default is @code{25}.
3900 Possible values are:
3903 zero round towards 0
3907 round towards -infinity
3909 round towards +infinity
3913 The default is @code{near}.
3917 Alternatively, the options can be specified as a flat string:
3918 @var{fps}[:@var{round}].
3920 See also the @ref{setpts} filter.
3922 @subsection Examples
3926 A typical usage in order to set the fps to 25:
3932 Sets the fps to 24, using abbreviation and rounding method to round to nearest:
3934 fps=fps=film:round=near
3940 Select one frame every N-th frame.
3942 This filter accepts the following option:
3945 Select frame after every @code{step} frames.
3946 Allowed values are positive integers higher than 0. Default value is @code{1}.
3952 Apply a frei0r effect to the input video.
3954 To enable compilation of this filter you need to install the frei0r
3955 header and configure FFmpeg with @code{--enable-frei0r}.
3957 This filter accepts the following options:
3962 The name to the frei0r effect to load. If the environment variable
3963 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
3964 directories specified by the colon separated list in @env{FREIOR_PATH},
3965 otherwise in the standard frei0r paths, which are in this order:
3966 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3967 @file{/usr/lib/frei0r-1/}.
3970 A '|'-separated list of parameters to pass to the frei0r effect.
3974 A frei0r effect parameter can be a boolean (whose values are specified
3975 with "y" and "n"), a double, a color (specified by the syntax
3976 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3977 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3978 description), a position (specified by the syntax @var{X}/@var{Y},
3979 @var{X} and @var{Y} being float numbers) and a string.
3981 The number and kind of parameters depend on the loaded effect. If an
3982 effect parameter is not specified the default value is set.
3984 @subsection Examples
3988 Apply the distort0r effect, set the first two double parameters:
3990 frei0r=filter_name=distort0r:filter_params=0.5|0.01
3994 Apply the colordistance effect, take a color as first parameter:
3996 frei0r=colordistance:0.2/0.3/0.4
3997 frei0r=colordistance:violet
3998 frei0r=colordistance:0x112233
4002 Apply the perspective effect, specify the top left and top right image
4005 frei0r=perspective:0.2/0.2|0.8/0.2
4009 For more information see:
4010 @url{http://frei0r.dyne.org}
4014 The filter accepts the following options:
4018 Set the luminance expression.
4020 Set the chrominance blue expression.
4022 Set the chrominance red expression.
4024 Set the alpha expression.
4026 Set the red expression.
4028 Set the green expression.
4030 Set the blue expression.
4033 The colorspace is selected according to the specified options. If one
4034 of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
4035 options is specified, the filter will automatically select a YCbCr
4036 colorspace. If one of the @option{red_expr}, @option{green_expr}, or
4037 @option{blue_expr} options is specified, it will select an RGB
4040 If one of the chrominance expression is not defined, it falls back on the other
4041 one. If no alpha expression is specified it will evaluate to opaque value.
4042 If none of chrominance expressions are specified, they will evaluate
4043 to the luminance expression.
4045 The expressions can use the following variables and functions:
4049 The sequential number of the filtered frame, starting from @code{0}.
4053 The coordinates of the current sample.
4057 The width and height of the image.
4061 Width and height scale depending on the currently filtered plane. It is the
4062 ratio between the corresponding luma plane number of pixels and the current
4063 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
4064 @code{0.5,0.5} for chroma planes.
4067 Time of the current frame, expressed in seconds.
4070 Return the value of the pixel at location (@var{x},@var{y}) of the current
4074 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
4078 Return the value of the pixel at location (@var{x},@var{y}) of the
4079 blue-difference chroma plane. Return 0 if there is no such plane.
4082 Return the value of the pixel at location (@var{x},@var{y}) of the
4083 red-difference chroma plane. Return 0 if there is no such plane.
4088 Return the value of the pixel at location (@var{x},@var{y}) of the
4089 red/green/blue component. Return 0 if there is no such component.
4092 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
4093 plane. Return 0 if there is no such plane.
4096 For functions, if @var{x} and @var{y} are outside the area, the value will be
4097 automatically clipped to the closer edge.
4099 @subsection Examples
4103 Flip the image horizontally:
4109 Generate a bidimensional sine wave, with angle @code{PI/3} and a
4110 wavelength of 100 pixels:
4112 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
4116 Generate a fancy enigmatic moving light:
4118 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
4122 Generate a quick emboss effect:
4124 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
4128 Modify RGB components depending on pixel position:
4130 geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
4136 Fix the banding artifacts that are sometimes introduced into nearly flat
4137 regions by truncation to 8bit color depth.
4138 Interpolate the gradients that should go where the bands are, and
4141 This filter is designed for playback only. Do not use it prior to
4142 lossy compression, because compression tends to lose the dither and
4143 bring back the bands.
4145 This filter accepts the following options:
4150 The maximum amount by which the filter will change any one pixel. Also the
4151 threshold for detecting nearly flat regions. Acceptable values range from .51 to
4152 64, default value is 1.2, out-of-range values will be clipped to the valid
4156 The neighborhood to fit the gradient to. A larger radius makes for smoother
4157 gradients, but also prevents the filter from modifying the pixels near detailed
4158 regions. Acceptable values are 8-32, default value is 16, out-of-range values
4159 will be clipped to the valid range.
4163 Alternatively, the options can be specified as a flat string:
4164 @var{strength}[:@var{radius}]
4166 @subsection Examples
4170 Apply the filter with a @code{3.5} strength and radius of @code{8}:
4176 Specify radius, omitting the strength (which will fall-back to the default
4187 Apply a Hald CLUT to a video stream.
4189 First input is the video stream to process, and second one is the Hald CLUT.
4190 The Hald CLUT input can be a simple picture or a complete video stream.
4192 The filter accepts the following options:
4196 Force termination when the shortest input terminates. Default is @code{0}.
4198 Continue applying the last CLUT after the end of the stream. A value of
4199 @code{0} disable the filter after the last frame of the CLUT is reached.
4200 Default is @code{1}.
4203 @code{haldclut} also has the same interpolation options as @ref{lut3d} (both
4204 filters share the same internals).
4206 More information about the Hald CLUT can be found on Eskil Steenberg's website
4207 (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}.
4209 @subsection Workflow examples
4211 @subsubsection Hald CLUT video stream
4213 Generate an identity Hald CLUT stream altered with various effects:
4215 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "hue=H=2*PI*t:s=sin(2*PI*t)+1, curves=cross_process" -t 10 -c:v ffv1 clut.nut
4218 Note: make sure you use a lossless codec.
4220 Then use it with @code{haldclut} to apply it on some random stream:
4222 ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
4225 The Hald CLUT will be applied to the 10 first seconds (duration of
4226 @file{clut.nut}), then the latest picture of that CLUT stream will be applied
4227 to the remaining frames of the @code{mandelbrot} stream.
4229 @subsubsection Hald CLUT with preview
4231 A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by
4232 @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the
4233 biggest possible square starting at the top left of the picture. The remaining
4234 padding pixels (bottom or right) will be ignored. This area can be used to add
4235 a preview of the Hald CLUT.
4237 Typically, the following generated Hald CLUT will be supported by the
4238 @code{haldclut} filter:
4241 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "
4242 pad=iw+320 [padded_clut];
4243 smptebars=s=320x256, split [a][b];
4244 [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
4245 [main][b] overlay=W-320" -frames:v 1 clut.png
4248 It contains the original and a preview of the effect of the CLUT: SMPTE color
4249 bars are displayed on the right-top, and below the same color bars processed by
4252 Then, the effect of this Hald CLUT can be visualized with:
4254 ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
4259 Flip the input video horizontally.
4261 For example to horizontally flip the input video with @command{ffmpeg}:
4263 ffmpeg -i in.avi -vf "hflip" out.avi
4267 This filter applies a global color histogram equalization on a
4270 It can be used to correct video that has a compressed range of pixel
4271 intensities. The filter redistributes the pixel intensities to
4272 equalize their distribution across the intensity range. It may be
4273 viewed as an "automatically adjusting contrast filter". This filter is
4274 useful only for correcting degraded or poorly captured source
4277 The filter accepts the following options:
4281 Determine the amount of equalization to be applied. As the strength
4282 is reduced, the distribution of pixel intensities more-and-more
4283 approaches that of the input frame. The value must be a float number
4284 in the range [0,1] and defaults to 0.200.
4287 Set the maximum intensity that can generated and scale the output
4288 values appropriately. The strength should be set as desired and then
4289 the intensity can be limited if needed to avoid washing-out. The value
4290 must be a float number in the range [0,1] and defaults to 0.210.
4293 Set the antibanding level. If enabled the filter will randomly vary
4294 the luminance of output pixels by a small amount to avoid banding of
4295 the histogram. Possible values are @code{none}, @code{weak} or
4296 @code{strong}. It defaults to @code{none}.
4301 Compute and draw a color distribution histogram for the input video.
4303 The computed histogram is a representation of distribution of color components
4306 The filter accepts the following options:
4312 It accepts the following values:
4315 standard histogram that display color components distribution in an image.
4316 Displays color graph for each color component. Shows distribution
4317 of the Y, U, V, A or G, B, R components, depending on input format,
4318 in current frame. Bellow each graph is color component scale meter.
4321 chroma values in vectorscope, if brighter more such chroma values are
4322 distributed in an image.
4323 Displays chroma values (U/V color placement) in two dimensional graph
4324 (which is called a vectorscope). It can be used to read of the hue and
4325 saturation of the current frame. At a same time it is a histogram.
4326 The whiter a pixel in the vectorscope, the more pixels of the input frame
4327 correspond to that pixel (that is the more pixels have this chroma value).
4328 The V component is displayed on the horizontal (X) axis, with the leftmost
4329 side being V = 0 and the rightmost side being V = 255.
4330 The U component is displayed on the vertical (Y) axis, with the top
4331 representing U = 0 and the bottom representing U = 255.
4333 The position of a white pixel in the graph corresponds to the chroma value
4334 of a pixel of the input clip. So the graph can be used to read of the
4335 hue (color flavor) and the saturation (the dominance of the hue in the color).
4336 As the hue of a color changes, it moves around the square. At the center of
4337 the square, the saturation is zero, which means that the corresponding pixel
4338 has no color. If you increase the amount of a specific color, while leaving
4339 the other colors unchanged, the saturation increases, and you move towards
4340 the edge of the square.
4343 chroma values in vectorscope, similar as @code{color} but actual chroma values
4347 per row/column color component graph. In row mode graph in the left side represents
4348 color component value 0 and right side represents value = 255. In column mode top
4349 side represents color component value = 0 and bottom side represents value = 255.
4351 Default value is @code{levels}.
4354 Set height of level in @code{levels}. Default value is @code{200}.
4355 Allowed range is [50, 2048].
4358 Set height of color scale in @code{levels}. Default value is @code{12}.
4359 Allowed range is [0, 40].
4362 Set step for @code{waveform} mode. Smaller values are useful to find out how much
4363 of same luminance values across input rows/columns are distributed.
4364 Default value is @code{10}. Allowed range is [1, 255].
4367 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
4368 Default is @code{row}.
4371 Set display mode for @code{waveform} and @code{levels}.
4372 It accepts the following values:
4375 Display separate graph for the color components side by side in
4376 @code{row} waveform mode or one below other in @code{column} waveform mode
4377 for @code{waveform} histogram mode. For @code{levels} histogram mode
4378 per color component graphs are placed one bellow other.
4380 This display mode in @code{waveform} histogram mode makes it easy to spot
4381 color casts in the highlights and shadows of an image, by comparing the
4382 contours of the top and the bottom of each waveform.
4383 Since whites, grays, and blacks are characterized by
4384 exactly equal amounts of red, green, and blue, neutral areas of the
4385 picture should display three waveforms of roughly equal width/height.
4386 If not, the correction is easy to make by making adjustments to level the
4390 Presents information that's identical to that in the @code{parade}, except
4391 that the graphs representing color components are superimposed directly
4394 This display mode in @code{waveform} histogram mode can make it easier to spot
4395 the relative differences or similarities in overlapping areas of the color
4396 components that are supposed to be identical, such as neutral whites, grays,
4399 Default is @code{parade}.
4402 Set mode for @code{levels}. Can be either @code{linear}, or @code{logarithmic}.
4403 Default is @code{linear}.
4406 @subsection Examples
4411 Calculate and draw histogram:
4413 ffplay -i input -vf histogram
4421 High precision/quality 3d denoise filter. This filter aims to reduce
4422 image noise producing smooth images and making still images really
4423 still. It should enhance compressibility.
4425 It accepts the following optional parameters:
4429 a non-negative float number which specifies spatial luma strength,
4432 @item chroma_spatial
4433 a non-negative float number which specifies spatial chroma strength,
4434 defaults to 3.0*@var{luma_spatial}/4.0
4437 a float number which specifies luma temporal strength, defaults to
4438 6.0*@var{luma_spatial}/4.0
4441 a float number which specifies chroma temporal strength, defaults to
4442 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
4447 Modify the hue and/or the saturation of the input.
4449 This filter accepts the following options:
4453 Specify the hue angle as a number of degrees. It accepts an expression,
4454 and defaults to "0".
4457 Specify the saturation in the [-10,10] range. It accepts an expression and
4461 Specify the hue angle as a number of radians. It accepts an
4462 expression, and defaults to "0".
4465 @option{h} and @option{H} are mutually exclusive, and can't be
4466 specified at the same time.
4468 The @option{h}, @option{H} and @option{s} option values are
4469 expressions containing the following constants:
4473 frame count of the input frame starting from 0
4476 presentation timestamp of the input frame expressed in time base units
4479 frame rate of the input video, NAN if the input frame rate is unknown
4482 timestamp expressed in seconds, NAN if the input timestamp is unknown
4485 time base of the input video
4488 @subsection Examples
4492 Set the hue to 90 degrees and the saturation to 1.0:
4498 Same command but expressing the hue in radians:
4504 Rotate hue and make the saturation swing between 0
4505 and 2 over a period of 1 second:
4507 hue="H=2*PI*t: s=sin(2*PI*t)+1"
4511 Apply a 3 seconds saturation fade-in effect starting at 0:
4516 The general fade-in expression can be written as:
4518 hue="s=min(0\, max((t-START)/DURATION\, 1))"
4522 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
4524 hue="s=max(0\, min(1\, (8-t)/3))"
4527 The general fade-out expression can be written as:
4529 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
4534 @subsection Commands
4536 This filter supports the following commands:
4541 Modify the hue and/or the saturation of the input video.
4542 The command accepts the same syntax of the corresponding option.
4544 If the specified expression is not valid, it is kept at its current
4550 Detect video interlacing type.
4552 This filter tries to detect if the input is interlaced or progressive,
4553 top or bottom field first.
4555 The filter accepts the following options:
4559 Set interlacing threshold.
4561 Set progressive threshold.
4566 Deinterleave or interleave fields.
4568 This filter allows to process interlaced images fields without
4569 deinterlacing them. Deinterleaving splits the input frame into 2
4570 fields (so called half pictures). Odd lines are moved to the top
4571 half of the output image, even lines to the bottom half.
4572 You can process (filter) them independently and then re-interleave them.
4574 The filter accepts the following options:
4578 @item chroma_mode, c
4580 Available values for @var{luma_mode}, @var{chroma_mode} and
4581 @var{alpha_mode} are:
4587 @item deinterleave, d
4588 Deinterleave fields, placing one above the other.
4591 Interleave fields. Reverse the effect of deinterleaving.
4593 Default value is @code{none}.
4596 @item chroma_swap, cs
4597 @item alpha_swap, as
4598 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
4603 Simple interlacing filter from progressive contents. This interleaves upper (or
4604 lower) lines from odd frames with lower (or upper) lines from even frames,
4605 halving the frame rate and preserving image height.
4608 Original Original New Frame
4609 Frame 'j' Frame 'j+1' (tff)
4610 ========== =========== ==================
4611 Line 0 --------------------> Frame 'j' Line 0
4612 Line 1 Line 1 ----> Frame 'j+1' Line 1
4613 Line 2 ---------------------> Frame 'j' Line 2
4614 Line 3 Line 3 ----> Frame 'j+1' Line 3
4616 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
4619 It accepts the following optional parameters:
4623 determines whether the interlaced frame is taken from the even (tff - default)
4624 or odd (bff) lines of the progressive frame.
4627 Enable (default) or disable the vertical lowpass filter to avoid twitter
4628 interlacing and reduce moire patterns.
4633 Deinterlace input video by applying Donald Graft's adaptive kernel
4634 deinterling. Work on interlaced parts of a video to produce
4637 The description of the accepted parameters follows.
4641 Set the threshold which affects the filter's tolerance when
4642 determining if a pixel line must be processed. It must be an integer
4643 in the range [0,255] and defaults to 10. A value of 0 will result in
4644 applying the process on every pixels.
4647 Paint pixels exceeding the threshold value to white if set to 1.
4651 Set the fields order. Swap fields if set to 1, leave fields alone if
4655 Enable additional sharpening if set to 1. Default is 0.
4658 Enable twoway sharpening if set to 1. Default is 0.
4661 @subsection Examples
4665 Apply default values:
4667 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
4671 Enable additional sharpening:
4677 Paint processed pixels in white:
4686 Apply a 3D LUT to an input video.
4688 The filter accepts the following options:
4692 Set the 3D LUT file name.
4694 Currently supported formats:
4706 Select interpolation mode.
4708 Available values are:
4712 Use values from the nearest defined point.
4714 Interpolate values using the 8 points defining a cube.
4716 Interpolate values using a tetrahedron.
4720 @section lut, lutrgb, lutyuv
4722 Compute a look-up table for binding each pixel component input value
4723 to an output value, and apply it to input video.
4725 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
4726 to an RGB input video.
4728 These filters accept the following options:
4731 set first pixel component expression
4733 set second pixel component expression
4735 set third pixel component expression
4737 set fourth pixel component expression, corresponds to the alpha component
4740 set red component expression
4742 set green component expression
4744 set blue component expression
4746 alpha component expression
4749 set Y/luminance component expression
4751 set U/Cb component expression
4753 set V/Cr component expression
4756 Each of them specifies the expression to use for computing the lookup table for
4757 the corresponding pixel component values.
4759 The exact component associated to each of the @var{c*} options depends on the
4762 The @var{lut} filter requires either YUV or RGB pixel formats in input,
4763 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
4765 The expressions can contain the following constants and functions:
4770 the input width and height
4773 input value for the pixel component
4776 the input value clipped in the @var{minval}-@var{maxval} range
4779 maximum value for the pixel component
4782 minimum value for the pixel component
4785 the negated value for the pixel component value clipped in the
4786 @var{minval}-@var{maxval} range , it corresponds to the expression
4787 "maxval-clipval+minval"
4790 the computed value in @var{val} clipped in the
4791 @var{minval}-@var{maxval} range
4793 @item gammaval(gamma)
4794 the computed gamma correction value of the pixel component value
4795 clipped in the @var{minval}-@var{maxval} range, corresponds to the
4797 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
4801 All expressions default to "val".
4803 @subsection Examples
4809 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
4810 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
4813 The above is the same as:
4815 lutrgb="r=negval:g=negval:b=negval"
4816 lutyuv="y=negval:u=negval:v=negval"
4826 Remove chroma components, turns the video into a graytone image:
4828 lutyuv="u=128:v=128"
4832 Apply a luma burning effect:
4838 Remove green and blue components:
4844 Set a constant alpha channel value on input:
4846 format=rgba,lutrgb=a="maxval-minval/2"
4850 Correct luminance gamma by a 0.5 factor:
4852 lutyuv=y=gammaval(0.5)
4856 Discard least significant bits of luma:
4858 lutyuv=y='bitand(val, 128+64+32)'
4864 Apply motion-compensation deinterlacing.
4866 It needs one field per frame as input and must thus be used together
4867 with yadif=1/3 or equivalent.
4869 This filter accepts the following options:
4872 Set the deinterlacing mode.
4874 It accepts one of the following values:
4879 use iterative motion estimation
4881 like @samp{slow}, but use multiple reference frames.
4883 Default value is @samp{fast}.
4886 Set the picture field parity assumed for the input video. It must be
4887 one of the following values:
4891 assume top field first
4893 assume bottom field first
4896 Default value is @samp{bff}.
4899 Set per-block quantization parameter (QP) used by the internal
4902 Higher values should result in a smoother motion vector field but less
4903 optimal individual vectors. Default value is 1.
4908 Apply an MPlayer filter to the input video.
4910 This filter provides a wrapper around most of the filters of
4913 This wrapper is considered experimental. Some of the wrapped filters
4914 may not work properly and we may drop support for them, as they will
4915 be implemented natively into FFmpeg. Thus you should avoid
4916 depending on them when writing portable scripts.
4918 The filters accepts the parameters:
4919 @var{filter_name}[:=]@var{filter_params}
4921 @var{filter_name} is the name of a supported MPlayer filter,
4922 @var{filter_params} is a string containing the parameters accepted by
4925 The list of the currently supported filters follows:
4942 The parameter syntax and behavior for the listed filters are the same
4943 of the corresponding MPlayer filters. For detailed instructions check
4944 the "VIDEO FILTERS" section in the MPlayer manual.
4946 @subsection Examples
4950 Adjust gamma, brightness, contrast:
4956 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
4960 Drop frames that do not differ greatly from the previous frame in
4961 order to reduce frame rate.
4963 The main use of this filter is for very-low-bitrate encoding
4964 (e.g. streaming over dialup modem), but it could in theory be used for
4965 fixing movies that were inverse-telecined incorrectly.
4967 A description of the accepted options follows.
4971 Set the maximum number of consecutive frames which can be dropped (if
4972 positive), or the minimum interval between dropped frames (if
4973 negative). If the value is 0, the frame is dropped unregarding the
4974 number of previous sequentially dropped frames.
4981 Set the dropping threshold values.
4983 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
4984 represent actual pixel value differences, so a threshold of 64
4985 corresponds to 1 unit of difference for each pixel, or the same spread
4986 out differently over the block.
4988 A frame is a candidate for dropping if no 8x8 blocks differ by more
4989 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
4990 meaning the whole image) differ by more than a threshold of @option{lo}.
4992 Default value for @option{hi} is 64*12, default value for @option{lo} is
4993 64*5, and default value for @option{frac} is 0.33.
5001 This filter accepts an integer in input, if non-zero it negates the
5002 alpha component (if available). The default value in input is 0.
5006 Force libavfilter not to use any of the specified pixel formats for the
5007 input to the next filter.
5009 This filter accepts the following parameters:
5013 A '|'-separated list of pixel format names, for example
5014 "pix_fmts=yuv420p|monow|rgb24".
5018 @subsection Examples
5022 Force libavfilter to use a format different from @var{yuv420p} for the
5023 input to the vflip filter:
5025 noformat=pix_fmts=yuv420p,vflip
5029 Convert the input video to any of the formats not contained in the list:
5031 noformat=yuv420p|yuv444p|yuv410p
5037 Add noise on video input frame.
5039 The filter accepts the following options:
5047 Set noise seed for specific pixel component or all pixel components in case
5048 of @var{all_seed}. Default value is @code{123457}.
5050 @item all_strength, alls
5051 @item c0_strength, c0s
5052 @item c1_strength, c1s
5053 @item c2_strength, c2s
5054 @item c3_strength, c3s
5055 Set noise strength for specific pixel component or all pixel components in case
5056 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
5058 @item all_flags, allf
5063 Set pixel component flags or set flags for all components if @var{all_flags}.
5064 Available values for component flags are:
5067 averaged temporal noise (smoother)
5069 mix random noise with a (semi)regular pattern
5071 temporal noise (noise pattern changes between frames)
5073 uniform noise (gaussian otherwise)
5077 @subsection Examples
5079 Add temporal and uniform noise to input video:
5081 noise=alls=20:allf=t+u
5086 Pass the video source unchanged to the output.
5090 Apply video transform using libopencv.
5092 To enable this filter install libopencv library and headers and
5093 configure FFmpeg with @code{--enable-libopencv}.
5095 This filter accepts the following parameters:
5100 The name of the libopencv filter to apply.
5103 The parameters to pass to the libopencv filter. If not specified the default
5108 Refer to the official libopencv documentation for more precise
5110 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
5112 Follows the list of supported libopencv filters.
5117 Dilate an image by using a specific structuring element.
5118 This filter corresponds to the libopencv function @code{cvDilate}.
5120 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
5122 @var{struct_el} represents a structuring element, and has the syntax:
5123 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
5125 @var{cols} and @var{rows} represent the number of columns and rows of
5126 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
5127 point, and @var{shape} the shape for the structuring element, and
5128 can be one of the values "rect", "cross", "ellipse", "custom".
5130 If the value for @var{shape} is "custom", it must be followed by a
5131 string of the form "=@var{filename}". The file with name
5132 @var{filename} is assumed to represent a binary image, with each
5133 printable character corresponding to a bright pixel. When a custom
5134 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
5135 or columns and rows of the read file are assumed instead.
5137 The default value for @var{struct_el} is "3x3+0x0/rect".
5139 @var{nb_iterations} specifies the number of times the transform is
5140 applied to the image, and defaults to 1.
5142 Follow some example:
5144 # use the default values
5147 # dilate using a structuring element with a 5x5 cross, iterate two times
5148 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
5150 # read the shape from the file diamond.shape, iterate two times
5151 # the file diamond.shape may contain a pattern of characters like this:
5157 # the specified cols and rows are ignored (but not the anchor point coordinates)
5158 ocv=dilate:0x0+2x2/custom=diamond.shape|2
5163 Erode an image by using a specific structuring element.
5164 This filter corresponds to the libopencv function @code{cvErode}.
5166 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
5167 with the same syntax and semantics as the @ref{dilate} filter.
5171 Smooth the input video.
5173 The filter takes the following parameters:
5174 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
5176 @var{type} is the type of smooth filter to apply, and can be one of
5177 the following values: "blur", "blur_no_scale", "median", "gaussian",
5178 "bilateral". The default value is "gaussian".
5180 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
5181 parameters whose meanings depend on smooth type. @var{param1} and
5182 @var{param2} accept integer positive values or 0, @var{param3} and
5183 @var{param4} accept float values.
5185 The default value for @var{param1} is 3, the default value for the
5186 other parameters is 0.
5188 These parameters correspond to the parameters assigned to the
5189 libopencv function @code{cvSmooth}.
5194 Overlay one video on top of another.
5196 It takes two inputs and one output, the first input is the "main"
5197 video on which the second input is overlayed.
5199 This filter accepts the following parameters:
5201 A description of the accepted options follows.
5206 Set the expression for the x and y coordinates of the overlayed video
5207 on the main video. Default value is "0" for both expressions. In case
5208 the expression is invalid, it is set to a huge value (meaning that the
5209 overlay will not be displayed within the output visible area).
5212 Set when the expressions for @option{x}, and @option{y} are evaluated.
5214 It accepts the following values:
5217 only evaluate expressions once during the filter initialization or
5218 when a command is processed
5221 evaluate expressions for each incoming frame
5224 Default value is @samp{frame}.
5227 If set to 1, force the output to terminate when the shortest input
5228 terminates. Default value is 0.
5231 Set the format for the output video.
5233 It accepts the following values:
5245 Default value is @samp{yuv420}.
5247 @item rgb @emph{(deprecated)}
5248 If set to 1, force the filter to accept inputs in the RGB
5249 color space. Default value is 0. This option is deprecated, use
5250 @option{format} instead.
5253 If set to 1, force the filter to draw the last overlay frame over the
5254 main input until the end of the stream. A value of 0 disables this
5255 behavior, which is enabled by default.
5258 The @option{x}, and @option{y} expressions can contain the following
5264 main input width and height
5268 overlay input width and height
5272 the computed values for @var{x} and @var{y}. They are evaluated for
5277 horizontal and vertical chroma subsample values of the output
5278 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
5282 the number of input frame, starting from 0
5285 the position in the file of the input frame, NAN if unknown
5288 timestamp expressed in seconds, NAN if the input timestamp is unknown
5291 Note that the @var{n}, @var{pos}, @var{t} variables are available only
5292 when evaluation is done @emph{per frame}, and will evaluate to NAN
5293 when @option{eval} is set to @samp{init}.
5295 Be aware that frames are taken from each input video in timestamp
5296 order, hence, if their initial timestamps differ, it is a a good idea
5297 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
5298 have them begin in the same zero timestamp, as it does the example for
5299 the @var{movie} filter.
5301 You can chain together more overlays but you should test the
5302 efficiency of such approach.
5304 @subsection Commands
5306 This filter supports the following commands:
5310 Modify the x and y of the overlay input.
5311 The command accepts the same syntax of the corresponding option.
5313 If the specified expression is not valid, it is kept at its current
5317 @subsection Examples
5321 Draw the overlay at 10 pixels from the bottom right corner of the main
5324 overlay=main_w-overlay_w-10:main_h-overlay_h-10
5327 Using named options the example above becomes:
5329 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
5333 Insert a transparent PNG logo in the bottom left corner of the input,
5334 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
5336 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
5340 Insert 2 different transparent PNG logos (second logo on bottom
5341 right corner) using the @command{ffmpeg} tool:
5343 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
5347 Add a transparent color layer on top of the main video, @code{WxH}
5348 must specify the size of the main input to the overlay filter:
5350 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
5354 Play an original video and a filtered version (here with the deshake
5355 filter) side by side using the @command{ffplay} tool:
5357 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
5360 The above command is the same as:
5362 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
5366 Make a sliding overlay appearing from the left to the right top part of the
5367 screen starting since time 2:
5369 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
5373 Compose output by putting two input videos side to side:
5375 ffmpeg -i left.avi -i right.avi -filter_complex "
5376 nullsrc=size=200x100 [background];
5377 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
5378 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
5379 [background][left] overlay=shortest=1 [background+left];
5380 [background+left][right] overlay=shortest=1:x=100 [left+right]
5385 Chain several overlays in cascade:
5387 nullsrc=s=200x200 [bg];
5388 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
5389 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
5390 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
5391 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
5392 [in3] null, [mid2] overlay=100:100 [out0]
5399 Apply Overcomplete Wavelet denoiser.
5401 The filter accepts the following options:
5407 Larger depth values will denoise lower frequency components more, but
5408 slow down filtering.
5410 Must be an int in the range 8-16, default is @code{8}.
5412 @item luma_strength, ls
5415 Must be a double value in the range 0-1000, default is @code{1.0}.
5417 @item chroma_strength, cs
5418 Set chroma strength.
5420 Must be a double value in the range 0-1000, default is @code{1.0}.
5425 Add paddings to the input image, and place the original input at the
5426 given coordinates @var{x}, @var{y}.
5428 This filter accepts the following parameters:
5433 Specify an expression for the size of the output image with the
5434 paddings added. If the value for @var{width} or @var{height} is 0, the
5435 corresponding input size is used for the output.
5437 The @var{width} expression can reference the value set by the
5438 @var{height} expression, and vice versa.
5440 The default value of @var{width} and @var{height} is 0.
5444 Specify an expression for the offsets where to place the input image
5445 in the padded area with respect to the top/left border of the output
5448 The @var{x} expression can reference the value set by the @var{y}
5449 expression, and vice versa.
5451 The default value of @var{x} and @var{y} is 0.
5454 Specify the color of the padded area, it can be the name of a color
5455 (case insensitive match) or a 0xRRGGBB[AA] sequence.
5457 The default value of @var{color} is "black".
5460 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
5461 options are expressions containing the following constants:
5466 the input video width and height
5470 same as @var{in_w} and @var{in_h}
5474 the output width and height, that is the size of the padded area as
5475 specified by the @var{width} and @var{height} expressions
5479 same as @var{out_w} and @var{out_h}
5483 x and y offsets as specified by the @var{x} and @var{y}
5484 expressions, or NAN if not yet specified
5487 same as @var{iw} / @var{ih}
5490 input sample aspect ratio
5493 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
5497 horizontal and vertical chroma subsample values. For example for the
5498 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
5501 @subsection Examples
5505 Add paddings with color "violet" to the input video. Output video
5506 size is 640x480, the top-left corner of the input video is placed at
5509 pad=640:480:0:40:violet
5512 The example above is equivalent to the following command:
5514 pad=width=640:height=480:x=0:y=40:color=violet
5518 Pad the input to get an output with dimensions increased by 3/2,
5519 and put the input video at the center of the padded area:
5521 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
5525 Pad the input to get a squared output with size equal to the maximum
5526 value between the input width and height, and put the input video at
5527 the center of the padded area:
5529 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
5533 Pad the input to get a final w/h ratio of 16:9:
5535 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
5539 In case of anamorphic video, in order to set the output display aspect
5540 correctly, it is necessary to use @var{sar} in the expression,
5541 according to the relation:
5543 (ih * X / ih) * sar = output_dar
5544 X = output_dar / sar
5547 Thus the previous example needs to be modified to:
5549 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
5553 Double output size and put the input video in the bottom-right
5554 corner of the output padded area:
5556 pad="2*iw:2*ih:ow-iw:oh-ih"
5560 @section pixdesctest
5562 Pixel format descriptor test filter, mainly useful for internal
5563 testing. The output video should be equal to the input video.
5567 format=monow, pixdesctest
5570 can be used to test the monowhite pixel format descriptor definition.
5574 Enable the specified chain of postprocessing subfilters using libpostproc. This
5575 library should be automatically selected with a GPL build (@code{--enable-gpl}).
5576 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
5577 Each subfilter and some options have a short and a long name that can be used
5578 interchangeably, i.e. dr/dering are the same.
5580 The filters accept the following options:
5584 Set postprocessing subfilters string.
5587 All subfilters share common options to determine their scope:
5591 Honor the quality commands for this subfilter.
5594 Do chrominance filtering, too (default).
5597 Do luminance filtering only (no chrominance).
5600 Do chrominance filtering only (no luminance).
5603 These options can be appended after the subfilter name, separated by a '|'.
5605 Available subfilters are:
5608 @item hb/hdeblock[|difference[|flatness]]
5609 Horizontal deblocking filter
5612 Difference factor where higher values mean more deblocking (default: @code{32}).
5614 Flatness threshold where lower values mean more deblocking (default: @code{39}).
5617 @item vb/vdeblock[|difference[|flatness]]
5618 Vertical deblocking filter
5621 Difference factor where higher values mean more deblocking (default: @code{32}).
5623 Flatness threshold where lower values mean more deblocking (default: @code{39}).
5626 @item ha/hadeblock[|difference[|flatness]]
5627 Accurate horizontal deblocking filter
5630 Difference factor where higher values mean more deblocking (default: @code{32}).
5632 Flatness threshold where lower values mean more deblocking (default: @code{39}).
5635 @item va/vadeblock[|difference[|flatness]]
5636 Accurate vertical deblocking filter
5639 Difference factor where higher values mean more deblocking (default: @code{32}).
5641 Flatness threshold where lower values mean more deblocking (default: @code{39}).
5645 The horizontal and vertical deblocking filters share the difference and
5646 flatness values so you cannot set different horizontal and vertical
5651 Experimental horizontal deblocking filter
5654 Experimental vertical deblocking filter
5659 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
5662 larger -> stronger filtering
5664 larger -> stronger filtering
5666 larger -> stronger filtering
5669 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
5672 Stretch luminance to @code{0-255}.
5675 @item lb/linblenddeint
5676 Linear blend deinterlacing filter that deinterlaces the given block by
5677 filtering all lines with a @code{(1 2 1)} filter.
5679 @item li/linipoldeint
5680 Linear interpolating deinterlacing filter that deinterlaces the given block by
5681 linearly interpolating every second line.
5683 @item ci/cubicipoldeint
5684 Cubic interpolating deinterlacing filter deinterlaces the given block by
5685 cubically interpolating every second line.
5687 @item md/mediandeint
5688 Median deinterlacing filter that deinterlaces the given block by applying a
5689 median filter to every second line.
5691 @item fd/ffmpegdeint
5692 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
5693 second line with a @code{(-1 4 2 4 -1)} filter.
5696 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
5697 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
5699 @item fq/forceQuant[|quantizer]
5700 Overrides the quantizer table from the input with the constant quantizer you
5708 Default pp filter combination (@code{hb|a,vb|a,dr|a})
5711 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
5714 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
5717 @subsection Examples
5721 Apply horizontal and vertical deblocking, deringing and automatic
5722 brightness/contrast:
5728 Apply default filters without brightness/contrast correction:
5734 Apply default filters and temporal denoiser:
5736 pp=default/tmpnoise|1|2|3
5740 Apply deblocking on luminance only, and switch vertical deblocking on or off
5741 automatically depending on available CPU time:
5749 Suppress a TV station logo, using an image file to determine which
5750 pixels comprise the logo. It works by filling in the pixels that
5751 comprise the logo with neighboring pixels.
5753 The filter accepts the following options:
5757 Set the filter bitmap file, which can be any image format supported by
5758 libavformat. The width and height of the image file must match those of the
5759 video stream being processed.
5762 Pixels in the provided bitmap image with a value of zero are not
5763 considered part of the logo, non-zero pixels are considered part of
5764 the logo. If you use white (255) for the logo and black (0) for the
5765 rest, you will be safe. For making the filter bitmap, it is
5766 recommended to take a screen capture of a black frame with the logo
5767 visible, and then using a threshold filter followed by the erode
5768 filter once or twice.
5770 If needed, little splotches can be fixed manually. Remember that if
5771 logo pixels are not covered, the filter quality will be much
5772 reduced. Marking too many pixels as part of the logo does not hurt as
5773 much, but it will increase the amount of blurring needed to cover over
5774 the image and will destroy more information than necessary, and extra
5775 pixels will slow things down on a large logo.
5779 Rotate video by an arbitrary angle expressed in radians.
5781 The filter accepts the following options:
5783 A description of the optional parameters follows.
5786 Set an expression for the angle by which to rotate the input video
5787 clockwise, expressed as a number of radians. A negative value will
5788 result in a counter-clockwise rotation. By default it is set to "0".
5790 This expression is evaluated for each frame.
5793 Set the output width expression, default value is "iw".
5794 This expression is evaluated just once during configuration.
5797 Set the output height expression, default value is "ih".
5798 This expression is evaluated just once during configuration.
5801 Enable bilinear interpolation if set to 1, a value of 0 disables
5802 it. Default value is 1.
5805 Set the color used to fill the output area not covered by the rotated
5806 image. If the special value "none" is selected then no background is
5807 printed (useful for example if the background is never shown). Default
5811 The expressions for the angle and the output size can contain the
5812 following constants and functions:
5816 sequential number of the input frame, starting from 0. It is always NAN
5817 before the first frame is filtered.
5820 time in seconds of the input frame, it is set to 0 when the filter is
5821 configured. It is always NAN before the first frame is filtered.
5825 horizontal and vertical chroma subsample values. For example for the
5826 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
5830 the input video width and heigth
5834 the output width and heigth, that is the size of the padded area as
5835 specified by the @var{width} and @var{height} expressions
5839 the minimal width/height required for completely containing the input
5840 video rotated by @var{a} radians.
5842 These are only available when computing the @option{out_w} and
5843 @option{out_h} expressions.
5846 @subsection Examples
5850 Rotate the input by PI/6 radians clockwise:
5856 Rotate the input by PI/6 radians counter-clockwise:
5862 Apply a constant rotation with period T, starting from an angle of PI/3:
5864 rotate=PI/3+2*PI*t/T
5868 Make the input video rotation oscillating with a period of T
5869 seconds and an amplitude of A radians:
5871 rotate=A*sin(2*PI/T*t)
5875 Rotate the video, output size is choosen so that the whole rotating
5876 input video is always completely contained in the output:
5878 rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
5882 Rotate the video, reduce the output size so that no background is ever
5885 rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
5889 @subsection Commands
5891 The filter supports the following commands:
5895 Set the angle expression.
5896 The command accepts the same syntax of the corresponding option.
5898 If the specified expression is not valid, it is kept at its current
5904 Apply Shape Adaptive Blur.
5906 The filter accepts the following options:
5909 @item luma_radius, lr
5910 Set luma blur filter strength, must be a value in range 0.1-4.0, default
5911 value is 1.0. A greater value will result in a more blurred image, and
5912 in slower processing.
5914 @item luma_pre_filter_radius, lpfr
5915 Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
5918 @item luma_strength, ls
5919 Set luma maximum difference between pixels to still be considered, must
5920 be a value in the 0.1-100.0 range, default value is 1.0.
5922 @item chroma_radius, cr
5923 Set chroma blur filter strength, must be a value in range 0.1-4.0. A
5924 greater value will result in a more blurred image, and in slower
5927 @item chroma_pre_filter_radius, cpfr
5928 Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
5930 @item chroma_strength, cs
5931 Set chroma maximum difference between pixels to still be considered,
5932 must be a value in the 0.1-100.0 range.
5935 Each chroma option value, if not explicitly specified, is set to the
5936 corresponding luma option value.
5940 Scale (resize) the input video, using the libswscale library.
5942 The scale filter forces the output display aspect ratio to be the same
5943 of the input, by changing the output sample aspect ratio.
5945 The filter accepts the following options:
5949 Set the output video width expression. Default value is @code{iw}. See
5950 below for the list of accepted constants.
5953 Set the output video height expression. Default value is @code{ih}.
5954 See below for the list of accepted constants.
5957 Set the interlacing. It accepts the following values:
5961 force interlaced aware scaling
5964 do not apply interlaced scaling
5967 select interlaced aware scaling depending on whether the source frames
5968 are flagged as interlaced or not
5971 Default value is @code{0}.
5974 Set libswscale scaling flags. If not explictly specified the filter
5975 applies a bilinear scaling algorithm.
5978 Set the video size, the value must be a valid abbreviation or in the
5979 form @var{width}x@var{height}.
5982 The values of the @var{w} and @var{h} options are expressions
5983 containing the following constants:
5988 the input width and height
5992 same as @var{in_w} and @var{in_h}
5996 the output (cropped) width and height
6000 same as @var{out_w} and @var{out_h}
6003 same as @var{iw} / @var{ih}
6006 input sample aspect ratio
6009 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
6013 horizontal and vertical chroma subsample values. For example for the
6014 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
6017 If the input image format is different from the format requested by
6018 the next filter, the scale filter will convert the input to the
6021 If the value for @var{w} or @var{h} is 0, the respective input
6022 size is used for the output.
6024 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
6025 respective output size, a value that maintains the aspect ratio of the input
6028 @subsection Examples
6032 Scale the input video to a size of 200x100:
6037 This is equivalent to:
6048 Specify a size abbreviation for the output size:
6053 which can also be written as:
6059 Scale the input to 2x:
6065 The above is the same as:
6071 Scale the input to 2x with forced interlaced scaling:
6073 scale=2*iw:2*ih:interl=1
6077 Scale the input to half size:
6083 Increase the width, and set the height to the same size:
6089 Seek for Greek harmony:
6096 Increase the height, and set the width to 3/2 of the height:
6098 scale=w=3/2*oh:h=3/5*ih
6102 Increase the size, but make the size a multiple of the chroma
6105 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
6109 Increase the width to a maximum of 500 pixels, keep the same input
6112 scale=w='min(500\, iw*3/2):h=-1'
6116 @section separatefields
6118 The @code{separatefields} takes a frame-based video input and splits
6119 each frame into its components fields, producing a new half height clip
6120 with twice the frame rate and twice the frame count.
6122 This filter use field-dominance information in frame to decide which
6123 of each pair of fields to place first in the output.
6124 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
6126 @section setdar, setsar
6128 The @code{setdar} filter sets the Display Aspect Ratio for the filter
6131 This is done by changing the specified Sample (aka Pixel) Aspect
6132 Ratio, according to the following equation:
6134 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
6137 Keep in mind that the @code{setdar} filter does not modify the pixel
6138 dimensions of the video frame. Also the display aspect ratio set by
6139 this filter may be changed by later filters in the filterchain,
6140 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
6143 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
6144 the filter output video.
6146 Note that as a consequence of the application of this filter, the
6147 output display aspect ratio will change according to the equation
6150 Keep in mind that the sample aspect ratio set by the @code{setsar}
6151 filter may be changed by later filters in the filterchain, e.g. if
6152 another "setsar" or a "setdar" filter is applied.
6154 The filters accept the following options:
6157 @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only)
6158 Set the aspect ratio used by the filter.
6160 The parameter can be a floating point number string, an expression, or
6161 a string of the form @var{num}:@var{den}, where @var{num} and
6162 @var{den} are the numerator and denominator of the aspect ratio. If
6163 the parameter is not specified, it is assumed the value "0".
6164 In case the form "@var{num}:@var{den}" is used, the @code{:} character
6168 Set the maximum integer value to use for expressing numerator and
6169 denominator when reducing the expressed aspect ratio to a rational.
6170 Default value is @code{100}.
6174 @subsection Examples
6179 To change the display aspect ratio to 16:9, specify one of the following:
6187 To change the sample aspect ratio to 10:11, specify:
6193 To set a display aspect ratio of 16:9, and specify a maximum integer value of
6194 1000 in the aspect ratio reduction, use the command:
6196 setdar=ratio=16/9:max=1000
6204 Force field for the output video frame.
6206 The @code{setfield} filter marks the interlace type field for the
6207 output frames. It does not change the input frame, but only sets the
6208 corresponding property, which affects how the frame is treated by
6209 following filters (e.g. @code{fieldorder} or @code{yadif}).
6211 The filter accepts the following options:
6216 Available values are:
6220 Keep the same field property.
6223 Mark the frame as bottom-field-first.
6226 Mark the frame as top-field-first.
6229 Mark the frame as progressive.
6235 Show a line containing various information for each input video frame.
6236 The input video is not modified.
6238 The shown line contains a sequence of key/value pairs of the form
6239 @var{key}:@var{value}.
6241 A description of each shown parameter follows:
6245 sequential number of the input frame, starting from 0
6248 Presentation TimeStamp of the input frame, expressed as a number of
6249 time base units. The time base unit depends on the filter input pad.
6252 Presentation TimeStamp of the input frame, expressed as a number of
6256 position of the frame in the input stream, -1 if this information in
6257 unavailable and/or meaningless (for example in case of synthetic video)
6263 sample aspect ratio of the input frame, expressed in the form
6267 size of the input frame, expressed in the form
6268 @var{width}x@var{height}
6271 interlaced mode ("P" for "progressive", "T" for top field first, "B"
6272 for bottom field first)
6275 1 if the frame is a key frame, 0 otherwise
6278 picture type of the input frame ("I" for an I-frame, "P" for a
6279 P-frame, "B" for a B-frame, "?" for unknown type).
6280 Check also the documentation of the @code{AVPictureType} enum and of
6281 the @code{av_get_picture_type_char} function defined in
6282 @file{libavutil/avutil.h}.
6285 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
6287 @item plane_checksum
6288 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
6289 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
6295 Blur the input video without impacting the outlines.
6297 The filter accepts the following options:
6300 @item luma_radius, lr
6301 Set the luma radius. The option value must be a float number in
6302 the range [0.1,5.0] that specifies the variance of the gaussian filter
6303 used to blur the image (slower if larger). Default value is 1.0.
6305 @item luma_strength, ls
6306 Set the luma strength. The option value must be a float number
6307 in the range [-1.0,1.0] that configures the blurring. A value included
6308 in [0.0,1.0] will blur the image whereas a value included in
6309 [-1.0,0.0] will sharpen the image. Default value is 1.0.
6311 @item luma_threshold, lt
6312 Set the luma threshold used as a coefficient to determine
6313 whether a pixel should be blurred or not. The option value must be an
6314 integer in the range [-30,30]. A value of 0 will filter all the image,
6315 a value included in [0,30] will filter flat areas and a value included
6316 in [-30,0] will filter edges. Default value is 0.
6318 @item chroma_radius, cr
6319 Set the chroma radius. The option value must be a float number in
6320 the range [0.1,5.0] that specifies the variance of the gaussian filter
6321 used to blur the image (slower if larger). Default value is 1.0.
6323 @item chroma_strength, cs
6324 Set the chroma strength. The option value must be a float number
6325 in the range [-1.0,1.0] that configures the blurring. A value included
6326 in [0.0,1.0] will blur the image whereas a value included in
6327 [-1.0,0.0] will sharpen the image. Default value is 1.0.
6329 @item chroma_threshold, ct
6330 Set the chroma threshold used as a coefficient to determine
6331 whether a pixel should be blurred or not. The option value must be an
6332 integer in the range [-30,30]. A value of 0 will filter all the image,
6333 a value included in [0,30] will filter flat areas and a value included
6334 in [-30,0] will filter edges. Default value is 0.
6337 If a chroma option is not explicitly set, the corresponding luma value
6342 Convert between different stereoscopic image formats.
6344 The filters accept the following options:
6348 Set stereoscopic image format of input.
6350 Available values for input image formats are:
6353 side by side parallel (left eye left, right eye right)
6356 side by side crosseye (right eye left, left eye right)
6359 side by side parallel with half width resolution
6360 (left eye left, right eye right)
6363 side by side crosseye with half width resolution
6364 (right eye left, left eye right)
6367 above-below (left eye above, right eye below)
6370 above-below (right eye above, left eye below)
6373 above-below with half height resolution
6374 (left eye above, right eye below)
6377 above-below with half height resolution
6378 (right eye above, left eye below)
6381 alternating frames (left eye first, right eye second)
6384 alternating frames (right eye first, left eye second)
6386 Default value is @samp{sbsl}.
6390 Set stereoscopic image format of output.
6392 Available values for output image formats are all the input formats as well as:
6395 anaglyph red/blue gray
6396 (red filter on left eye, blue filter on right eye)
6399 anaglyph red/green gray
6400 (red filter on left eye, green filter on right eye)
6403 anaglyph red/cyan gray
6404 (red filter on left eye, cyan filter on right eye)
6407 anaglyph red/cyan half colored
6408 (red filter on left eye, cyan filter on right eye)
6411 anaglyph red/cyan color
6412 (red filter on left eye, cyan filter on right eye)
6415 anaglyph red/cyan color optimized with the least squares projection of dubois
6416 (red filter on left eye, cyan filter on right eye)
6419 anaglyph green/magenta gray
6420 (green filter on left eye, magenta filter on right eye)
6423 anaglyph green/magenta half colored
6424 (green filter on left eye, magenta filter on right eye)
6427 anaglyph green/magenta colored
6428 (green filter on left eye, magenta filter on right eye)
6431 anaglyph green/magenta color optimized with the least squares projection of dubois
6432 (green filter on left eye, magenta filter on right eye)
6435 anaglyph yellow/blue gray
6436 (yellow filter on left eye, blue filter on right eye)
6439 anaglyph yellow/blue half colored
6440 (yellow filter on left eye, blue filter on right eye)
6443 anaglyph yellow/blue colored
6444 (yellow filter on left eye, blue filter on right eye)
6447 anaglyph yellow/blue color optimized with the least squares projection of dubois
6448 (yellow filter on left eye, blue filter on right eye)
6451 interleaved rows (left eye has top row, right eye starts on next row)
6454 interleaved rows (right eye has top row, left eye starts on next row)
6457 mono output (left eye only)
6460 mono output (right eye only)
6463 Default value is @samp{arcd}.
6466 @subsection Examples
6470 Convert input video from side by side parallel to anaglyph yellow/blue dubois:
6476 Convert input video from above bellow (left eye above, right eye below) to side by side crosseye.
6484 Apply a simple postprocessing filter that compresses and decompresses the image
6485 at several (or - in the case of @option{quality} level @code{6} - all) shifts
6486 and average the results.
6488 The filter accepts the following options:
6492 Set quality. This option defines the number of levels for averaging. It accepts
6493 an integer in the range 0-6. If set to @code{0}, the filter will have no
6494 effect. A value of @code{6} means the higher quality. For each increment of
6495 that value the speed drops by a factor of approximately 2. Default value is
6499 Force a constant quantization parameter. If not set, the filter will use the QP
6500 from the video stream (if available).
6503 Set thresholding mode. Available modes are:
6507 Set hard thresholding (default).
6509 Set soft thresholding (better de-ringing effect, but likely blurrier).
6513 Enable the use of the QP from the B-Frames if set to @code{1}. Using this
6514 option may cause flicker since the B-Frames have often larger QP. Default is
6515 @code{0} (not enabled).
6521 Draw subtitles on top of input video using the libass library.
6523 To enable compilation of this filter you need to configure FFmpeg with
6524 @code{--enable-libass}. This filter also requires a build with libavcodec and
6525 libavformat to convert the passed subtitles file to ASS (Advanced Substation
6526 Alpha) subtitles format.
6528 The filter accepts the following options:
6532 Set the filename of the subtitle file to read. It must be specified.
6535 Specify the size of the original video, the video for which the ASS file
6536 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
6537 necessary to correctly scale the fonts if the aspect ratio has been changed.
6540 Set subtitles input character encoding. @code{subtitles} filter only. Only
6541 useful if not UTF-8.
6544 If the first key is not specified, it is assumed that the first value
6545 specifies the @option{filename}.
6547 For example, to render the file @file{sub.srt} on top of the input
6548 video, use the command:
6553 which is equivalent to:
6555 subtitles=filename=sub.srt
6560 Scale the input by 2x and smooth using the Super2xSaI (Scale and
6561 Interpolate) pixel art scaling algorithm.
6563 Useful for enlarging pixel art images without reducing sharpness.
6570 Apply telecine process to the video.
6572 This filter accepts the following options:
6581 The default value is @code{top}.
6585 A string of numbers representing the pulldown pattern you wish to apply.
6586 The default value is @code{23}.
6590 Some typical patterns:
6595 24p: 2332 (preferred)
6602 24p: 222222222223 ("Euro pulldown")
6608 Select the most representative frame in a given sequence of consecutive frames.
6610 The filter accepts the following options:
6614 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
6615 will pick one of them, and then handle the next batch of @var{n} frames until
6616 the end. Default is @code{100}.
6619 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
6620 value will result in a higher memory usage, so a high value is not recommended.
6622 @subsection Examples
6626 Extract one picture each 50 frames:
6632 Complete example of a thumbnail creation with @command{ffmpeg}:
6634 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
6640 Tile several successive frames together.
6642 The filter accepts the following options:
6647 Set the grid size (i.e. the number of lines and columns) in the form
6651 Set the maximum number of frames to render in the given area. It must be less
6652 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
6653 the area will be used.
6656 Set the outer border margin in pixels.
6659 Set the inner border thickness (i.e. the number of pixels between frames). For
6660 more advanced padding options (such as having different values for the edges),
6661 refer to the pad video filter.
6665 @subsection Examples
6669 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
6671 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
6673 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
6674 duplicating each output frame to accomodate the originally detected frame
6678 Display @code{5} pictures in an area of @code{3x2} frames,
6679 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
6680 mixed flat and named options:
6682 tile=3x2:nb_frames=5:padding=7:margin=2
6688 Perform various types of temporal field interlacing.
6690 Frames are counted starting from 1, so the first input frame is
6693 The filter accepts the following options:
6698 Specify the mode of the interlacing. This option can also be specified
6699 as a value alone. See below for a list of values for this option.
6701 Available values are:
6705 Move odd frames into the upper field, even into the lower field,
6706 generating a double height frame at half frame rate.
6709 Only output even frames, odd frames are dropped, generating a frame with
6710 unchanged height at half frame rate.
6713 Only output odd frames, even frames are dropped, generating a frame with
6714 unchanged height at half frame rate.
6717 Expand each frame to full height, but pad alternate lines with black,
6718 generating a frame with double height at the same input frame rate.
6720 @item interleave_top, 4
6721 Interleave the upper field from odd frames with the lower field from
6722 even frames, generating a frame with unchanged height at half frame rate.
6724 @item interleave_bottom, 5
6725 Interleave the lower field from odd frames with the upper field from
6726 even frames, generating a frame with unchanged height at half frame rate.
6728 @item interlacex2, 6
6729 Double frame rate with unchanged height. Frames are inserted each
6730 containing the second temporal field from the previous input frame and
6731 the first temporal field from the next input frame. This mode relies on
6732 the top_field_first flag. Useful for interlaced video displays with no
6733 field synchronisation.
6736 Numeric values are deprecated but are accepted for backward
6737 compatibility reasons.
6739 Default mode is @code{merge}.
6742 Specify flags influencing the filter process.
6744 Available value for @var{flags} is:
6747 @item low_pass_filter, vlfp
6748 Enable vertical low-pass filtering in the filter.
6749 Vertical low-pass filtering is required when creating an interlaced
6750 destination from a progressive source which contains high-frequency
6751 vertical detail. Filtering will reduce interlace 'twitter' and Moire
6754 Vertical low-pass filtering can only be enabled for @option{mode}
6755 @var{interleave_top} and @var{interleave_bottom}.
6762 Transpose rows with columns in the input video and optionally flip it.
6764 This filter accepts the following options:
6769 Specify the transposition direction.
6771 Can assume the following values:
6773 @item 0, 4, cclock_flip
6774 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
6782 Rotate by 90 degrees clockwise, that is:
6790 Rotate by 90 degrees counterclockwise, that is:
6797 @item 3, 7, clock_flip
6798 Rotate by 90 degrees clockwise and vertically flip, that is:
6806 For values between 4-7, the transposition is only done if the input
6807 video geometry is portrait and not landscape. These values are
6808 deprecated, the @code{passthrough} option should be used instead.
6810 Numerical values are deprecated, and should be dropped in favor of
6814 Do not apply the transposition if the input geometry matches the one
6815 specified by the specified value. It accepts the following values:
6818 Always apply transposition.
6820 Preserve portrait geometry (when @var{height} >= @var{width}).
6822 Preserve landscape geometry (when @var{width} >= @var{height}).
6825 Default value is @code{none}.
6828 For example to rotate by 90 degrees clockwise and preserve portrait
6831 transpose=dir=1:passthrough=portrait
6834 The command above can also be specified as:
6836 transpose=1:portrait
6840 Trim the input so that the output contains one continuous subpart of the input.
6842 This filter accepts the following options:
6845 Timestamp (in seconds) of the start of the kept section. I.e. the frame with the
6846 timestamp @var{start} will be the first frame in the output.
6849 Timestamp (in seconds) of the first frame that will be dropped. I.e. the frame
6850 immediately preceding the one with the timestamp @var{end} will be the last
6851 frame in the output.
6854 Same as @var{start}, except this option sets the start timestamp in timebase
6855 units instead of seconds.
6858 Same as @var{end}, except this option sets the end timestamp in timebase units
6862 Maximum duration of the output in seconds.
6865 Number of the first frame that should be passed to output.
6868 Number of the first frame that should be dropped.
6871 Note that the first two sets of the start/end options and the @option{duration}
6872 option look at the frame timestamp, while the _frame variants simply count the
6873 frames that pass through the filter. Also note that this filter does not modify
6874 the timestamps. If you wish that the output timestamps start at zero, insert a
6875 setpts filter after the trim filter.
6877 If multiple start or end options are set, this filter tries to be greedy and
6878 keep all the frames that match at least one of the specified constraints. To keep
6879 only the part that matches all the constraints at once, chain multiple trim
6882 The defaults are such that all the input is kept. So it is possible to set e.g.
6883 just the end values to keep everything before the specified time.
6888 drop everything except the second minute of input
6890 ffmpeg -i INPUT -vf trim=60:120
6894 keep only the first second
6896 ffmpeg -i INPUT -vf trim=duration=1
6904 Sharpen or blur the input video.
6906 It accepts the following parameters:
6909 @item luma_msize_x, lx
6910 Set the luma matrix horizontal size. It must be an odd integer between
6911 3 and 63, default value is 5.
6913 @item luma_msize_y, ly
6914 Set the luma matrix vertical size. It must be an odd integer between 3
6915 and 63, default value is 5.
6917 @item luma_amount, la
6918 Set the luma effect strength. It can be a float number, reasonable
6919 values lay between -1.5 and 1.5.
6921 Negative values will blur the input video, while positive values will
6922 sharpen it, a value of zero will disable the effect.
6924 Default value is 1.0.
6926 @item chroma_msize_x, cx
6927 Set the chroma matrix horizontal size. It must be an odd integer
6928 between 3 and 63, default value is 5.
6930 @item chroma_msize_y, cy
6931 Set the chroma matrix vertical size. It must be an odd integer
6932 between 3 and 63, default value is 5.
6934 @item chroma_amount, ca
6935 Set the chroma effect strength. It can be a float number, reasonable
6936 values lay between -1.5 and 1.5.
6938 Negative values will blur the input video, while positive values will
6939 sharpen it, a value of zero will disable the effect.
6941 Default value is 0.0.
6944 If set to 1, specify using OpenCL capabilities, only available if
6945 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
6949 All parameters are optional and default to the equivalent of the
6950 string '5:5:1.0:5:5:0.0'.
6952 @subsection Examples
6956 Apply strong luma sharpen effect:
6958 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
6962 Apply strong blur of both luma and chroma parameters:
6964 unsharp=7:7:-2:7:7:-2
6968 @anchor{vidstabdetect}
6969 @section vidstabdetect
6971 Analyze video stabilization/deshaking. Perform pass 1 of 2, see
6972 @ref{vidstabtransform} for pass 2.
6974 This filter generates a file with relative translation and rotation
6975 transform information about subsequent frames, which is then used by
6976 the @ref{vidstabtransform} filter.
6978 To enable compilation of this filter you need to configure FFmpeg with
6979 @code{--enable-libvidstab}.
6981 This filter accepts the following options:
6985 Set the path to the file used to write the transforms information.
6986 Default value is @file{transforms.trf}.
6989 Set how shaky the video is and how quick the camera is. It accepts an
6990 integer in the range 1-10, a value of 1 means little shakiness, a
6991 value of 10 means strong shakiness. Default value is 5.
6994 Set the accuracy of the detection process. It must be a value in the
6995 range 1-15. A value of 1 means low accuracy, a value of 15 means high
6996 accuracy. Default value is 9.
6999 Set stepsize of the search process. The region around minimum is
7000 scanned with 1 pixel resolution. Default value is 6.
7003 Set minimum contrast. Below this value a local measurement field is
7004 discarded. Must be a floating point value in the range 0-1. Default
7008 Set reference frame number for tripod mode.
7010 If enabled, the motion of the frames is compared to a reference frame
7011 in the filtered stream, identified by the specified number. The idea
7012 is to compensate all movements in a more-or-less static scene and keep
7013 the camera view absolutely still.
7015 If set to 0, it is disabled. The frames are counted starting from 1.
7018 Show fields and transforms in the resulting frames. It accepts an
7019 integer in the range 0-2. Default value is 0, which disables any
7023 @subsection Examples
7033 Analyze strongly shaky movie and put the results in file
7034 @file{mytransforms.trf}:
7036 vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
7040 Visualize the result of internal transformations in the resulting
7043 vidstabdetect=show=1
7047 Analyze a video with medium shakiness using @command{ffmpeg}:
7049 ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
7053 @anchor{vidstabtransform}
7054 @section vidstabtransform
7056 Video stabilization/deshaking: pass 2 of 2,
7057 see @ref{vidstabdetect} for pass 1.
7059 Read a file with transform information for each frame and
7060 apply/compensate them. Together with the @ref{vidstabdetect}
7061 filter this can be used to deshake videos. See also
7062 @url{http://public.hronopik.de/vid.stab}. It is important to also use
7063 the unsharp filter, see below.
7065 To enable compilation of this filter you need to configure FFmpeg with
7066 @code{--enable-libvidstab}.
7068 This filter accepts the following options:
7073 path to the file used to read the transforms (default: @file{transforms.trf})
7076 number of frames (value*2 + 1) used for lowpass filtering the camera movements
7077 (default: 10). For example a number of 10 means that 21 frames are used
7078 (10 in the past and 10 in the future) to smoothen the motion in the
7079 video. A larger values leads to a smoother video, but limits the
7080 acceleration of the camera (pan/tilt movements).
7083 maximal number of pixels to translate frames (default: -1 no limit)
7086 maximal angle in radians (degree*PI/180) to rotate frames (default: -1
7090 How to deal with borders that may be visible due to movement
7091 compensation. Available values are:
7095 keep image information from previous frame (default)
7097 fill the border black
7103 keep transforms normal (default)
7110 consider transforms as
7115 relative to previous frame (default)
7120 percentage to zoom (default: 0)
7129 if 1 then optimal zoom value is determined (default).
7130 Optimal zoom means no (or only little) border should be visible.
7131 Note that the value given at zoom is added to the one calculated
7135 type of interpolation
7137 Available values are:
7142 linear only horizontal
7144 linear in both directions (default)
7146 cubic in both directions (slow)
7150 virtual tripod mode means that the video is stabilized such that the
7151 camera stays stationary. Use also @code{tripod} option of
7152 @ref{vidstabdetect}.
7157 virtual tripod mode: equivalent to @code{relative=0:smoothing=0}
7162 @subsection Examples
7166 typical call with default default values:
7167 (note the unsharp filter which is always recommended)
7169 ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
7173 zoom in a bit more and load transform data from a given file
7175 vidstabtransform=zoom=5:input="mytransforms.trf"
7179 smoothen the video even more
7181 vidstabtransform=smoothing=30
7188 Flip the input video vertically.
7190 For example, to vertically flip a video with @command{ffmpeg}:
7192 ffmpeg -i in.avi -vf "vflip" out.avi
7197 Make or reverse a natural vignetting effect.
7199 The filter accepts the following options:
7203 Set lens angle expression as a number of radians.
7205 The value is clipped in the @code{[0,PI/2]} range.
7207 Default value: @code{"PI/5"}
7211 Set center coordinates expressions. Respectively @code{"w/2"} and @code{"h/2"}
7215 Set forward/backward mode.
7217 Available modes are:
7220 The larger the distance from the central point, the darker the image becomes.
7223 The larger the distance from the central point, the brighter the image becomes.
7224 This can be used to reverse a vignette effect, though there is no automatic
7225 detection to extract the lens @option{angle} and other settings (yet). It can
7226 also be used to create a burning effect.
7229 Default value is @samp{forward}.
7232 Set evaluation mode for the expressions (@option{angle}, @option{x0}, @option{y0}).
7234 It accepts the following values:
7237 Evaluate expressions only once during the filter initialization.
7240 Evaluate expressions for each incoming frame. This is way slower than the
7241 @samp{init} mode since it requires all the scalers to be re-computed, but it
7242 allows advanced dynamic expressions.
7245 Default value is @samp{init}.
7248 Set dithering to reduce the circular banding effects. Default is @code{1}
7252 Set vignette aspect. This setting allows to adjust the shape of the vignette.
7253 Setting this value to the SAR of the input will make a rectangular vignetting
7254 following the dimensions of the video.
7256 Default is @code{1/1}.
7259 @subsection Expressions
7261 The @option{alpha}, @option{x0} and @option{y0} expressions can contain the
7262 following parameters.
7267 input width and height
7270 the number of input frame, starting from 0
7273 the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in
7274 @var{TB} units, NAN if undefined
7277 frame rate of the input video, NAN if the input frame rate is unknown
7280 the PTS (Presentation TimeStamp) of the filtered video frame,
7281 expressed in seconds, NAN if undefined
7284 time base of the input video
7288 @subsection Examples
7292 Apply simple strong vignetting effect:
7298 Make a flickering vignetting:
7300 vignette='PI/4+random(1)*PI/50':eval=frame
7308 Deinterlace the input video ("yadif" means "yet another deinterlacing
7311 This filter accepts the following options:
7317 The interlacing mode to adopt, accepts one of the following values:
7321 output 1 frame for each frame
7323 output 1 frame for each field
7324 @item 2, send_frame_nospatial
7325 like @code{send_frame} but skip spatial interlacing check
7326 @item 3, send_field_nospatial
7327 like @code{send_field} but skip spatial interlacing check
7330 Default value is @code{send_frame}.
7333 The picture field parity assumed for the input interlaced video, accepts one of
7334 the following values:
7338 assume top field first
7340 assume bottom field first
7342 enable automatic detection
7345 Default value is @code{auto}.
7346 If interlacing is unknown or decoder does not export this information,
7347 top field first will be assumed.
7350 Specify which frames to deinterlace. Accept one of the following
7355 deinterlace all frames
7357 only deinterlace frames marked as interlaced
7360 Default value is @code{all}.
7363 @c man end VIDEO FILTERS
7365 @chapter Video Sources
7366 @c man begin VIDEO SOURCES
7368 Below is a description of the currently available video sources.
7372 Buffer video frames, and make them available to the filter chain.
7374 This source is mainly intended for a programmatic use, in particular
7375 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
7377 This source accepts the following options:
7382 Specify the size (width and height) of the buffered video frames.
7391 A string representing the pixel format of the buffered video frames.
7392 It may be a number corresponding to a pixel format, or a pixel format
7396 Specify the timebase assumed by the timestamps of the buffered frames.
7399 Specify the frame rate expected for the video stream.
7401 @item pixel_aspect, sar
7402 Specify the sample aspect ratio assumed by the video frames.
7405 Specify the optional parameters to be used for the scale filter which
7406 is automatically inserted when an input change is detected in the
7407 input size or format.
7412 buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
7415 will instruct the source to accept video frames with size 320x240 and
7416 with format "yuv410p", assuming 1/24 as the timestamps timebase and
7417 square pixels (1:1 sample aspect ratio).
7418 Since the pixel format with name "yuv410p" corresponds to the number 6
7419 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
7420 this example corresponds to:
7422 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
7425 Alternatively, the options can be specified as a flat string, but this
7426 syntax is deprecated:
7428 @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}]
7432 Create a pattern generated by an elementary cellular automaton.
7434 The initial state of the cellular automaton can be defined through the
7435 @option{filename}, and @option{pattern} options. If such options are
7436 not specified an initial state is created randomly.
7438 At each new frame a new row in the video is filled with the result of
7439 the cellular automaton next generation. The behavior when the whole
7440 frame is filled is defined by the @option{scroll} option.
7442 This source accepts the following options:
7446 Read the initial cellular automaton state, i.e. the starting row, from
7448 In the file, each non-whitespace character is considered an alive
7449 cell, a newline will terminate the row, and further characters in the
7450 file will be ignored.
7453 Read the initial cellular automaton state, i.e. the starting row, from
7454 the specified string.
7456 Each non-whitespace character in the string is considered an alive
7457 cell, a newline will terminate the row, and further characters in the
7458 string will be ignored.
7461 Set the video rate, that is the number of frames generated per second.
7464 @item random_fill_ratio, ratio
7465 Set the random fill ratio for the initial cellular automaton row. It
7466 is a floating point number value ranging from 0 to 1, defaults to
7469 This option is ignored when a file or a pattern is specified.
7471 @item random_seed, seed
7472 Set the seed for filling randomly the initial row, must be an integer
7473 included between 0 and UINT32_MAX. If not specified, or if explicitly
7474 set to -1, the filter will try to use a good random seed on a best
7478 Set the cellular automaton rule, it is a number ranging from 0 to 255.
7479 Default value is 110.
7482 Set the size of the output video.
7484 If @option{filename} or @option{pattern} is specified, the size is set
7485 by default to the width of the specified initial state row, and the
7486 height is set to @var{width} * PHI.
7488 If @option{size} is set, it must contain the width of the specified
7489 pattern string, and the specified pattern will be centered in the
7492 If a filename or a pattern string is not specified, the size value
7493 defaults to "320x518" (used for a randomly generated initial state).
7496 If set to 1, scroll the output upward when all the rows in the output
7497 have been already filled. If set to 0, the new generated row will be
7498 written over the top row just after the bottom row is filled.
7501 @item start_full, full
7502 If set to 1, completely fill the output with generated rows before
7503 outputting the first frame.
7504 This is the default behavior, for disabling set the value to 0.
7507 If set to 1, stitch the left and right row edges together.
7508 This is the default behavior, for disabling set the value to 0.
7511 @subsection Examples
7515 Read the initial state from @file{pattern}, and specify an output of
7518 cellauto=f=pattern:s=200x400
7522 Generate a random initial row with a width of 200 cells, with a fill
7525 cellauto=ratio=2/3:s=200x200
7529 Create a pattern generated by rule 18 starting by a single alive cell
7530 centered on an initial row with width 100:
7532 cellauto=p=@@:s=100x400:full=0:rule=18
7536 Specify a more elaborated initial pattern:
7538 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
7545 Generate a Mandelbrot set fractal, and progressively zoom towards the
7546 point specified with @var{start_x} and @var{start_y}.
7548 This source accepts the following options:
7553 Set the terminal pts value. Default value is 400.
7556 Set the terminal scale value.
7557 Must be a floating point value. Default value is 0.3.
7560 Set the inner coloring mode, that is the algorithm used to draw the
7561 Mandelbrot fractal internal region.
7563 It shall assume one of the following values:
7568 Show time until convergence.
7570 Set color based on point closest to the origin of the iterations.
7575 Default value is @var{mincol}.
7578 Set the bailout value. Default value is 10.0.
7581 Set the maximum of iterations performed by the rendering
7582 algorithm. Default value is 7189.
7585 Set outer coloring mode.
7586 It shall assume one of following values:
7588 @item iteration_count
7589 Set iteration cound mode.
7590 @item normalized_iteration_count
7591 set normalized iteration count mode.
7593 Default value is @var{normalized_iteration_count}.
7596 Set frame rate, expressed as number of frames per second. Default
7600 Set frame size. Default value is "640x480".
7603 Set the initial scale value. Default value is 3.0.
7606 Set the initial x position. Must be a floating point value between
7607 -100 and 100. Default value is -0.743643887037158704752191506114774.
7610 Set the initial y position. Must be a floating point value between
7611 -100 and 100. Default value is -0.131825904205311970493132056385139.
7616 Generate various test patterns, as generated by the MPlayer test filter.
7618 The size of the generated video is fixed, and is 256x256.
7619 This source is useful in particular for testing encoding features.
7621 This source accepts the following options:
7626 Specify the frame rate of the sourced video, as the number of frames
7627 generated per second. It has to be a string in the format
7628 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
7629 number or a valid video frame rate abbreviation. The default value is
7633 Set the video duration of the sourced video. The accepted syntax is:
7638 See also the function @code{av_parse_time()}.
7640 If not specified, or the expressed duration is negative, the video is
7641 supposed to be generated forever.
7645 Set the number or the name of the test to perform. Supported tests are:
7660 Default value is "all", which will cycle through the list of all tests.
7663 For example the following:
7668 will generate a "dc_luma" test pattern.
7672 Provide a frei0r source.
7674 To enable compilation of this filter you need to install the frei0r
7675 header and configure FFmpeg with @code{--enable-frei0r}.
7677 This source accepts the following options:
7682 The size of the video to generate, may be a string of the form
7683 @var{width}x@var{height} or a frame size abbreviation.
7686 Framerate of the generated video, may be a string of the form
7687 @var{num}/@var{den} or a frame rate abbreviation.
7690 The name to the frei0r source to load. For more information regarding frei0r and
7691 how to set the parameters read the section @ref{frei0r} in the description of
7695 A '|'-separated list of parameters to pass to the frei0r source.
7699 For example, to generate a frei0r partik0l source with size 200x200
7700 and frame rate 10 which is overlayed on the overlay filter main input:
7702 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
7707 Generate a life pattern.
7709 This source is based on a generalization of John Conway's life game.
7711 The sourced input represents a life grid, each pixel represents a cell
7712 which can be in one of two possible states, alive or dead. Every cell
7713 interacts with its eight neighbours, which are the cells that are
7714 horizontally, vertically, or diagonally adjacent.
7716 At each interaction the grid evolves according to the adopted rule,
7717 which specifies the number of neighbor alive cells which will make a
7718 cell stay alive or born. The @option{rule} option allows to specify
7721 This source accepts the following options:
7725 Set the file from which to read the initial grid state. In the file,
7726 each non-whitespace character is considered an alive cell, and newline
7727 is used to delimit the end of each row.
7729 If this option is not specified, the initial grid is generated
7733 Set the video rate, that is the number of frames generated per second.
7736 @item random_fill_ratio, ratio
7737 Set the random fill ratio for the initial random grid. It is a
7738 floating point number value ranging from 0 to 1, defaults to 1/PHI.
7739 It is ignored when a file is specified.
7741 @item random_seed, seed
7742 Set the seed for filling the initial random grid, must be an integer
7743 included between 0 and UINT32_MAX. If not specified, or if explicitly
7744 set to -1, the filter will try to use a good random seed on a best
7750 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
7751 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
7752 @var{NS} specifies the number of alive neighbor cells which make a
7753 live cell stay alive, and @var{NB} the number of alive neighbor cells
7754 which make a dead cell to become alive (i.e. to "born").
7755 "s" and "b" can be used in place of "S" and "B", respectively.
7757 Alternatively a rule can be specified by an 18-bits integer. The 9
7758 high order bits are used to encode the next cell state if it is alive
7759 for each number of neighbor alive cells, the low order bits specify
7760 the rule for "borning" new cells. Higher order bits encode for an
7761 higher number of neighbor cells.
7762 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
7763 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
7765 Default value is "S23/B3", which is the original Conway's game of life
7766 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
7767 cells, and will born a new cell if there are three alive cells around
7771 Set the size of the output video.
7773 If @option{filename} is specified, the size is set by default to the
7774 same size of the input file. If @option{size} is set, it must contain
7775 the size specified in the input file, and the initial grid defined in
7776 that file is centered in the larger resulting area.
7778 If a filename is not specified, the size value defaults to "320x240"
7779 (used for a randomly generated initial grid).
7782 If set to 1, stitch the left and right grid edges together, and the
7783 top and bottom edges also. Defaults to 1.
7786 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
7787 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
7788 value from 0 to 255.
7791 Set the color of living (or new born) cells.
7794 Set the color of dead cells. If @option{mold} is set, this is the first color
7795 used to represent a dead cell.
7798 Set mold color, for definitely dead and moldy cells.
7801 @subsection Examples
7805 Read a grid from @file{pattern}, and center it on a grid of size
7808 life=f=pattern:s=300x300
7812 Generate a random grid of size 200x200, with a fill ratio of 2/3:
7814 life=ratio=2/3:s=200x200
7818 Specify a custom rule for evolving a randomly generated grid:
7824 Full example with slow death effect (mold) using @command{ffplay}:
7826 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
7831 @anchor{haldclutsrc}
7835 @anchor{smptehdbars}
7837 @section color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc
7839 The @code{color} source provides an uniformly colored input.
7841 The @code{haldclutsrc} source provides an identity Hald CLUT. See also
7842 @ref{haldclut} filter.
7844 The @code{nullsrc} source returns unprocessed video frames. It is
7845 mainly useful to be employed in analysis / debugging tools, or as the
7846 source for filters which ignore the input data.
7848 The @code{rgbtestsrc} source generates an RGB test pattern useful for
7849 detecting RGB vs BGR issues. You should see a red, green and blue
7850 stripe from top to bottom.
7852 The @code{smptebars} source generates a color bars pattern, based on
7853 the SMPTE Engineering Guideline EG 1-1990.
7855 The @code{smptehdbars} source generates a color bars pattern, based on
7856 the SMPTE RP 219-2002.
7858 The @code{testsrc} source generates a test video pattern, showing a
7859 color pattern, a scrolling gradient and a timestamp. This is mainly
7860 intended for testing purposes.
7862 The sources accept the following options:
7867 Specify the color of the source, only available in the @code{color}
7868 source. It can be the name of a color (case insensitive match) or a
7869 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
7870 default value is "black".
7873 Specify the level of the Hald CLUT, only available in the @code{haldclutsrc}
7874 source. A level of @code{N} generates a picture of @code{N*N*N} by @code{N*N*N}
7875 pixels to be used as identity matrix for 3D lookup tables. Each component is
7876 coded on a @code{1/(N*N)} scale.
7879 Specify the size of the sourced video, it may be a string of the form
7880 @var{width}x@var{height}, or the name of a size abbreviation. The
7881 default value is "320x240".
7883 This option is not available with the @code{haldclutsrc} filter.
7886 Specify the frame rate of the sourced video, as the number of frames
7887 generated per second. It has to be a string in the format
7888 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
7889 number or a valid video frame rate abbreviation. The default value is
7893 Set the sample aspect ratio of the sourced video.
7896 Set the video duration of the sourced video. The accepted syntax is:
7898 [-]HH[:MM[:SS[.m...]]]
7901 See also the function @code{av_parse_time()}.
7903 If not specified, or the expressed duration is negative, the video is
7904 supposed to be generated forever.
7907 Set the number of decimals to show in the timestamp, only available in the
7908 @code{testsrc} source.
7910 The displayed timestamp value will correspond to the original
7911 timestamp value multiplied by the power of 10 of the specified
7912 value. Default value is 0.
7915 For example the following:
7917 testsrc=duration=5.3:size=qcif:rate=10
7920 will generate a video with a duration of 5.3 seconds, with size
7921 176x144 and a frame rate of 10 frames per second.
7923 The following graph description will generate a red source
7924 with an opacity of 0.2, with size "qcif" and a frame rate of 10
7927 color=c=red@@0.2:s=qcif:r=10
7930 If the input content is to be ignored, @code{nullsrc} can be used. The
7931 following command generates noise in the luminance plane by employing
7932 the @code{geq} filter:
7934 nullsrc=s=256x256, geq=random(1)*255:128:128
7937 @subsection Commands
7939 The @code{color} source supports the following commands:
7943 Set the color of the created image. Accepts the same syntax of the
7944 corresponding @option{color} option.
7947 @c man end VIDEO SOURCES
7949 @chapter Video Sinks
7950 @c man begin VIDEO SINKS
7952 Below is a description of the currently available video sinks.
7956 Buffer video frames, and make them available to the end of the filter
7959 This sink is mainly intended for a programmatic use, in particular
7960 through the interface defined in @file{libavfilter/buffersink.h}
7961 or the options system.
7963 It accepts a pointer to an AVBufferSinkContext structure, which
7964 defines the incoming buffers' formats, to be passed as the opaque
7965 parameter to @code{avfilter_init_filter} for initialization.
7969 Null video sink, do absolutely nothing with the input video. It is
7970 mainly useful as a template and to be employed in analysis / debugging
7973 @c man end VIDEO SINKS
7975 @chapter Multimedia Filters
7976 @c man begin MULTIMEDIA FILTERS
7978 Below is a description of the currently available multimedia filters.
7980 @section avectorscope
7982 Convert input audio to a video output, representing the audio vector
7985 The filter is used to measure the difference between channels of stereo
7986 audio stream. A monoaural signal, consisting of identical left and right
7987 signal, results in straight vertical line. Any stereo separation is visible
7988 as a deviation from this line, creating a Lissajous figure.
7989 If the straight (or deviation from it) but horizontal line appears this
7990 indicates that the left and right channels are out of phase.
7992 The filter accepts the following options:
7996 Set the vectorscope mode.
7998 Available values are:
8001 Lissajous rotated by 45 degrees.
8004 Same as above but not rotated.
8007 Default value is @samp{lissajous}.
8010 Set the video size for the output. Default value is @code{400x400}.
8013 Set the output frame rate. Default value is @code{25}.
8018 Specify the red, green and blue contrast. Default values are @code{40}, @code{160} and @code{80}.
8019 Allowed range is @code{[0, 255]}.
8024 Specify the red, green and blue fade. Default values are @code{15}, @code{10} and @code{5}.
8025 Allowed range is @code{[0, 255]}.
8028 Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}.
8031 @subsection Examples
8035 Complete example using @command{ffplay}:
8037 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
8038 [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
8044 Concatenate audio and video streams, joining them together one after the
8047 The filter works on segments of synchronized video and audio streams. All
8048 segments must have the same number of streams of each type, and that will
8049 also be the number of streams at output.
8051 The filter accepts the following options:
8056 Set the number of segments. Default is 2.
8059 Set the number of output video streams, that is also the number of video
8060 streams in each segment. Default is 1.
8063 Set the number of output audio streams, that is also the number of video
8064 streams in each segment. Default is 0.
8067 Activate unsafe mode: do not fail if segments have a different format.
8071 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
8072 @var{a} audio outputs.
8074 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
8075 segment, in the same order as the outputs, then the inputs for the second
8078 Related streams do not always have exactly the same duration, for various
8079 reasons including codec frame size or sloppy authoring. For that reason,
8080 related synchronized streams (e.g. a video and its audio track) should be
8081 concatenated at once. The concat filter will use the duration of the longest
8082 stream in each segment (except the last one), and if necessary pad shorter
8083 audio streams with silence.
8085 For this filter to work correctly, all segments must start at timestamp 0.
8087 All corresponding streams must have the same parameters in all segments; the
8088 filtering system will automatically select a common pixel format for video
8089 streams, and a common sample format, sample rate and channel layout for
8090 audio streams, but other settings, such as resolution, must be converted
8091 explicitly by the user.
8093 Different frame rates are acceptable but will result in variable frame rate
8094 at output; be sure to configure the output file to handle it.
8096 @subsection Examples
8100 Concatenate an opening, an episode and an ending, all in bilingual version
8101 (video in stream 0, audio in streams 1 and 2):
8103 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
8104 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
8105 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
8106 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
8110 Concatenate two parts, handling audio and video separately, using the
8111 (a)movie sources, and adjusting the resolution:
8113 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
8114 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
8115 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
8117 Note that a desync will happen at the stitch if the audio and video streams
8118 do not have exactly the same duration in the first file.
8124 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
8125 it unchanged. By default, it logs a message at a frequency of 10Hz with the
8126 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
8127 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
8129 The filter also has a video output (see the @var{video} option) with a real
8130 time graph to observe the loudness evolution. The graphic contains the logged
8131 message mentioned above, so it is not printed anymore when this option is set,
8132 unless the verbose logging is set. The main graphing area contains the
8133 short-term loudness (3 seconds of analysis), and the gauge on the right is for
8134 the momentary loudness (400 milliseconds).
8136 More information about the Loudness Recommendation EBU R128 on
8137 @url{http://tech.ebu.ch/loudness}.
8139 The filter accepts the following options:
8144 Activate the video output. The audio stream is passed unchanged whether this
8145 option is set or no. The video stream will be the first output stream if
8146 activated. Default is @code{0}.
8149 Set the video size. This option is for video only. Default and minimum
8150 resolution is @code{640x480}.
8153 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
8154 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
8155 other integer value between this range is allowed.
8158 Set metadata injection. If set to @code{1}, the audio input will be segmented
8159 into 100ms output frames, each of them containing various loudness information
8160 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
8162 Default is @code{0}.
8165 Force the frame logging level.
8167 Available values are:
8170 information logging level
8172 verbose logging level
8175 By default, the logging level is set to @var{info}. If the @option{video} or
8176 the @option{metadata} options are set, it switches to @var{verbose}.
8179 @subsection Examples
8183 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
8185 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
8189 Run an analysis with @command{ffmpeg}:
8191 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
8195 @section interleave, ainterleave
8197 Temporally interleave frames from several inputs.
8199 @code{interleave} works with video inputs, @code{ainterleave} with audio.
8201 These filters read frames from several inputs and send the oldest
8202 queued frame to the output.
8204 Input streams must have a well defined, monotonically increasing frame
8207 In order to submit one frame to output, these filters need to enqueue
8208 at least one frame for each input, so they cannot work in case one
8209 input is not yet terminated and will not receive incoming frames.
8211 For example consider the case when one input is a @code{select} filter
8212 which always drop input frames. The @code{interleave} filter will keep
8213 reading from that input, but it will never be able to send new frames
8214 to output until the input will send an end-of-stream signal.
8216 Also, depending on inputs synchronization, the filters will drop
8217 frames in case one input receives more frames than the other ones, and
8218 the queue is already filled.
8220 These filters accept the following options:
8224 Set the number of different inputs, it is 2 by default.
8227 @subsection Examples
8231 Interleave frames belonging to different streams using @command{ffmpeg}:
8233 ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
8237 Add flickering blur effect:
8239 select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
8243 @section perms, aperms
8245 Set read/write permissions for the output frames.
8247 These filters are mainly aimed at developers to test direct path in the
8248 following filter in the filtergraph.
8250 The filters accept the following options:
8254 Select the permissions mode.
8256 It accepts the following values:
8259 Do nothing. This is the default.
8261 Set all the output frames read-only.
8263 Set all the output frames directly writable.
8265 Make the frame read-only if writable, and writable if read-only.
8267 Set each output frame read-only or writable randomly.
8271 Set the seed for the @var{random} mode, must be an integer included between
8272 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
8273 @code{-1}, the filter will try to use a good random seed on a best effort
8277 Note: in case of auto-inserted filter between the permission filter and the
8278 following one, the permission might not be received as expected in that
8279 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
8280 perms/aperms filter can avoid this problem.
8282 @section select, aselect
8284 Select frames to pass in output.
8286 This filter accepts the following options:
8291 Set expression, which is evaluated for each input frame.
8293 If the expression is evaluated to zero, the frame is discarded.
8295 If the evaluation result is negative or NaN, the frame is sent to the
8296 first output; otherwise it is sent to the output with index
8297 @code{ceil(val)-1}, assuming that the input index starts from 0.
8299 For example a value of @code{1.2} corresponds to the output with index
8300 @code{ceil(1.2)-1 = 2-1 = 1}, that is the second output.
8303 Set the number of outputs. The output to which to send the selected
8304 frame is based on the result of the evaluation. Default value is 1.
8307 The expression can contain the following constants:
8311 the sequential number of the filtered frame, starting from 0
8314 the sequential number of the selected frame, starting from 0
8316 @item prev_selected_n
8317 the sequential number of the last selected frame, NAN if undefined
8320 timebase of the input timestamps
8323 the PTS (Presentation TimeStamp) of the filtered video frame,
8324 expressed in @var{TB} units, NAN if undefined
8327 the PTS (Presentation TimeStamp) of the filtered video frame,
8328 expressed in seconds, NAN if undefined
8331 the PTS of the previously filtered video frame, NAN if undefined
8333 @item prev_selected_pts
8334 the PTS of the last previously filtered video frame, NAN if undefined
8336 @item prev_selected_t
8337 the PTS of the last previously selected video frame, NAN if undefined
8340 the PTS of the first video frame in the video, NAN if undefined
8343 the time of the first video frame in the video, NAN if undefined
8345 @item pict_type @emph{(video only)}
8346 the type of the filtered frame, can assume one of the following
8358 @item interlace_type @emph{(video only)}
8359 the frame interlace type, can assume one of the following values:
8362 the frame is progressive (not interlaced)
8364 the frame is top-field-first
8366 the frame is bottom-field-first
8369 @item consumed_sample_n @emph{(audio only)}
8370 the number of selected samples before the current frame
8372 @item samples_n @emph{(audio only)}
8373 the number of samples in the current frame
8375 @item sample_rate @emph{(audio only)}
8376 the input sample rate
8379 1 if the filtered frame is a key-frame, 0 otherwise
8382 the position in the file of the filtered frame, -1 if the information
8383 is not available (e.g. for synthetic video)
8385 @item scene @emph{(video only)}
8386 value between 0 and 1 to indicate a new scene; a low value reflects a low
8387 probability for the current frame to introduce a new scene, while a higher
8388 value means the current frame is more likely to be one (see the example below)
8392 The default value of the select expression is "1".
8394 @subsection Examples
8398 Select all frames in input:
8403 The example above is the same as:
8415 Select only I-frames:
8417 select='eq(pict_type\,I)'
8421 Select one frame every 100:
8423 select='not(mod(n\,100))'
8427 Select only frames contained in the 10-20 time interval:
8429 select='gte(t\,10)*lte(t\,20)'
8433 Select only I frames contained in the 10-20 time interval:
8435 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
8439 Select frames with a minimum distance of 10 seconds:
8441 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
8445 Use aselect to select only audio frames with samples number > 100:
8447 aselect='gt(samples_n\,100)'
8451 Create a mosaic of the first scenes:
8453 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
8456 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
8460 Send even and odd frames to separate outputs, and compose them:
8462 select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
8466 @section sendcmd, asendcmd
8468 Send commands to filters in the filtergraph.
8470 These filters read commands to be sent to other filters in the
8473 @code{sendcmd} must be inserted between two video filters,
8474 @code{asendcmd} must be inserted between two audio filters, but apart
8475 from that they act the same way.
8477 The specification of commands can be provided in the filter arguments
8478 with the @var{commands} option, or in a file specified by the
8479 @var{filename} option.
8481 These filters accept the following options:
8484 Set the commands to be read and sent to the other filters.
8486 Set the filename of the commands to be read and sent to the other
8490 @subsection Commands syntax
8492 A commands description consists of a sequence of interval
8493 specifications, comprising a list of commands to be executed when a
8494 particular event related to that interval occurs. The occurring event
8495 is typically the current frame time entering or leaving a given time
8498 An interval is specified by the following syntax:
8500 @var{START}[-@var{END}] @var{COMMANDS};
8503 The time interval is specified by the @var{START} and @var{END} times.
8504 @var{END} is optional and defaults to the maximum time.
8506 The current frame time is considered within the specified interval if
8507 it is included in the interval [@var{START}, @var{END}), that is when
8508 the time is greater or equal to @var{START} and is lesser than
8511 @var{COMMANDS} consists of a sequence of one or more command
8512 specifications, separated by ",", relating to that interval. The
8513 syntax of a command specification is given by:
8515 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
8518 @var{FLAGS} is optional and specifies the type of events relating to
8519 the time interval which enable sending the specified command, and must
8520 be a non-null sequence of identifier flags separated by "+" or "|" and
8521 enclosed between "[" and "]".
8523 The following flags are recognized:
8526 The command is sent when the current frame timestamp enters the
8527 specified interval. In other words, the command is sent when the
8528 previous frame timestamp was not in the given interval, and the
8532 The command is sent when the current frame timestamp leaves the
8533 specified interval. In other words, the command is sent when the
8534 previous frame timestamp was in the given interval, and the
8538 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
8541 @var{TARGET} specifies the target of the command, usually the name of
8542 the filter class or a specific filter instance name.
8544 @var{COMMAND} specifies the name of the command for the target filter.
8546 @var{ARG} is optional and specifies the optional list of argument for
8547 the given @var{COMMAND}.
8549 Between one interval specification and another, whitespaces, or
8550 sequences of characters starting with @code{#} until the end of line,
8551 are ignored and can be used to annotate comments.
8553 A simplified BNF description of the commands specification syntax
8556 @var{COMMAND_FLAG} ::= "enter" | "leave"
8557 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
8558 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
8559 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
8560 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
8561 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
8564 @subsection Examples
8568 Specify audio tempo change at second 4:
8570 asendcmd=c='4.0 atempo tempo 1.5',atempo
8574 Specify a list of drawtext and hue commands in a file.
8576 # show text in the interval 5-10
8577 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
8578 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
8580 # desaturate the image in the interval 15-20
8581 15.0-20.0 [enter] hue s 0,
8582 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
8584 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
8586 # apply an exponential saturation fade-out effect, starting from time 25
8587 25 [enter] hue s exp(25-t)
8590 A filtergraph allowing to read and process the above command list
8591 stored in a file @file{test.cmd}, can be specified with:
8593 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
8598 @section setpts, asetpts
8600 Change the PTS (presentation timestamp) of the input frames.
8602 @code{setpts} works on video frames, @code{asetpts} on audio frames.
8604 This filter accepts the following options:
8609 The expression which is evaluated for each frame to construct its timestamp.
8613 The expression is evaluated through the eval API and can contain the following
8618 frame rate, only defined for constant frame-rate video
8621 the presentation timestamp in input
8624 the count of the input frame for video or the number of consumed samples,
8625 not including the current frame for audio, starting from 0.
8627 @item NB_CONSUMED_SAMPLES
8628 the number of consumed samples, not including the current frame (only
8632 the number of samples in the current frame (only audio)
8634 @item SAMPLE_RATE, SR
8638 the PTS of the first frame
8641 the time in seconds of the first frame
8644 tell if the current frame is interlaced
8647 the time in seconds of the current frame
8653 original position in the file of the frame, or undefined if undefined
8654 for the current frame
8660 previous input time in seconds
8666 previous output time in seconds
8669 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
8673 wallclock (RTC) time at the start of the movie in microseconds
8676 @subsection Examples
8680 Start counting PTS from zero
8686 Apply fast motion effect:
8692 Apply slow motion effect:
8698 Set fixed rate of 25 frames per second:
8704 Set fixed rate 25 fps with some jitter:
8706 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
8710 Apply an offset of 10 seconds to the input PTS:
8716 Generate timestamps from a "live source" and rebase onto the current timebase:
8718 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
8722 Generate timestamps by counting samples:
8729 @section settb, asettb
8731 Set the timebase to use for the output frames timestamps.
8732 It is mainly useful for testing timebase configuration.
8734 This filter accepts the following options:
8739 The expression which is evaluated into the output timebase.
8743 The value for @option{tb} is an arithmetic expression representing a
8744 rational. The expression can contain the constants "AVTB" (the default
8745 timebase), "intb" (the input timebase) and "sr" (the sample rate,
8746 audio only). Default value is "intb".
8748 @subsection Examples
8752 Set the timebase to 1/25:
8758 Set the timebase to 1/10:
8764 Set the timebase to 1001/1000:
8770 Set the timebase to 2*intb:
8776 Set the default timebase value:
8782 @section showspectrum
8784 Convert input audio to a video output, representing the audio frequency
8787 The filter accepts the following options:
8791 Specify the video size for the output. Default value is @code{640x512}.
8794 Specify if the spectrum should slide along the window. Default value is
8798 Specify display mode.
8800 It accepts the following values:
8803 all channels are displayed in the same row
8805 all channels are displayed in separate rows
8808 Default value is @samp{combined}.
8811 Specify display color mode.
8813 It accepts the following values:
8816 each channel is displayed in a separate color
8818 each channel is is displayed using the same color scheme
8821 Default value is @samp{channel}.
8824 Specify scale used for calculating intensity color values.
8826 It accepts the following values:
8831 square root, default
8838 Default value is @samp{sqrt}.
8841 Set saturation modifier for displayed colors. Negative values provide
8842 alternative color scheme. @code{0} is no saturation at all.
8843 Saturation must be in [-10.0, 10.0] range.
8844 Default value is @code{1}.
8847 The usage is very similar to the showwaves filter; see the examples in that
8850 @subsection Examples
8854 Large window with logarithmic color scaling:
8856 showspectrum=s=1280x480:scale=log
8860 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
8862 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
8863 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
8869 Convert input audio to a video output, representing the samples waves.
8871 The filter accepts the following options:
8875 Specify the video size for the output. Default value is "600x240".
8880 Available values are:
8883 Draw a point for each sample.
8886 Draw a vertical line for each sample.
8889 Default value is @code{point}.
8892 Set the number of samples which are printed on the same column. A
8893 larger value will decrease the frame rate. Must be a positive
8894 integer. This option can be set only if the value for @var{rate}
8895 is not explicitly specified.
8898 Set the (approximate) output frame rate. This is done by setting the
8899 option @var{n}. Default value is "25".
8903 @subsection Examples
8907 Output the input file audio and the corresponding video representation
8910 amovie=a.mp3,asplit[out0],showwaves[out1]
8914 Create a synthetic signal and show it with showwaves, forcing a
8915 frame rate of 30 frames per second:
8917 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
8921 @section split, asplit
8923 Split input into several identical outputs.
8925 @code{asplit} works with audio input, @code{split} with video.
8927 The filter accepts a single parameter which specifies the number of outputs. If
8928 unspecified, it defaults to 2.
8930 @subsection Examples
8934 Create two separate outputs from the same input:
8936 [in] split [out0][out1]
8940 To create 3 or more outputs, you need to specify the number of
8943 [in] asplit=3 [out0][out1][out2]
8947 Create two separate outputs from the same input, one cropped and
8950 [in] split [splitout1][splitout2];
8951 [splitout1] crop=100:100:0:0 [cropout];
8952 [splitout2] pad=200:200:100:100 [padout];
8956 Create 5 copies of the input audio with @command{ffmpeg}:
8958 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
8964 Receive commands sent through a libzmq client, and forward them to
8965 filters in the filtergraph.
8967 @code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq}
8968 must be inserted between two video filters, @code{azmq} between two
8971 To enable these filters you need to install the libzmq library and
8972 headers and configure FFmpeg with @code{--enable-libzmq}.
8974 For more information about libzmq see:
8975 @url{http://www.zeromq.org/}
8977 The @code{zmq} and @code{azmq} filters work as a libzmq server, which
8978 receives messages sent through a network interface defined by the
8979 @option{bind_address} option.
8981 The received message must be in the form:
8983 @var{TARGET} @var{COMMAND} [@var{ARG}]
8986 @var{TARGET} specifies the target of the command, usually the name of
8987 the filter class or a specific filter instance name.
8989 @var{COMMAND} specifies the name of the command for the target filter.
8991 @var{ARG} is optional and specifies the optional argument list for the
8992 given @var{COMMAND}.
8994 Upon reception, the message is processed and the corresponding command
8995 is injected into the filtergraph. Depending on the result, the filter
8996 will send a reply to the client, adopting the format:
8998 @var{ERROR_CODE} @var{ERROR_REASON}
9002 @var{MESSAGE} is optional.
9004 @subsection Examples
9006 Look at @file{tools/zmqsend} for an example of a zmq client which can
9007 be used to send commands processed by these filters.
9009 Consider the following filtergraph generated by @command{ffplay}
9011 ffplay -dumpgraph 1 -f lavfi "
9012 color=s=100x100:c=red [l];
9013 color=s=100x100:c=blue [r];
9014 nullsrc=s=200x100, zmq [bg];
9015 [bg][l] overlay [bg+l];
9016 [bg+l][r] overlay=x=100 "
9019 To change the color of the left side of the video, the following
9020 command can be used:
9022 echo Parsed_color_0 c yellow | tools/zmqsend
9025 To change the right side:
9027 echo Parsed_color_1 c pink | tools/zmqsend
9030 @c man end MULTIMEDIA FILTERS
9032 @chapter Multimedia Sources
9033 @c man begin MULTIMEDIA SOURCES
9035 Below is a description of the currently available multimedia sources.
9039 This is the same as @ref{movie} source, except it selects an audio
9045 Read audio and/or video stream(s) from a movie container.
9047 This filter accepts the following options:
9051 The name of the resource to read (not necessarily a file but also a device or a
9052 stream accessed through some protocol).
9054 @item format_name, f
9055 Specifies the format assumed for the movie to read, and can be either
9056 the name of a container or an input device. If not specified the
9057 format is guessed from @var{movie_name} or by probing.
9059 @item seek_point, sp
9060 Specifies the seek point in seconds, the frames will be output
9061 starting from this seek point, the parameter is evaluated with
9062 @code{av_strtod} so the numerical value may be suffixed by an IS
9063 postfix. Default value is "0".
9066 Specifies the streams to read. Several streams can be specified,
9067 separated by "+". The source will then have as many outputs, in the
9068 same order. The syntax is explained in the ``Stream specifiers''
9069 section in the ffmpeg manual. Two special names, "dv" and "da" specify
9070 respectively the default (best suited) video and audio stream. Default
9071 is "dv", or "da" if the filter is called as "amovie".
9073 @item stream_index, si
9074 Specifies the index of the video stream to read. If the value is -1,
9075 the best suited video stream will be automatically selected. Default
9076 value is "-1". Deprecated. If the filter is called "amovie", it will select
9077 audio instead of video.
9080 Specifies how many times to read the stream in sequence.
9081 If the value is less than 1, the stream will be read again and again.
9082 Default value is "1".
9084 Note that when the movie is looped the source timestamps are not
9085 changed, so it will generate non monotonically increasing timestamps.
9088 This filter allows to overlay a second video on top of main input of
9089 a filtergraph as shown in this graph:
9091 input -----------> deltapts0 --> overlay --> output
9094 movie --> scale--> deltapts1 -------+
9097 @subsection Examples
9101 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
9102 on top of the input labelled as "in":
9104 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
9105 [in] setpts=PTS-STARTPTS [main];
9106 [main][over] overlay=16:16 [out]
9110 Read from a video4linux2 device, and overlay it on top of the input
9113 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
9114 [in] setpts=PTS-STARTPTS [main];
9115 [main][over] overlay=16:16 [out]
9119 Read the first video stream and the audio stream with id 0x81 from
9120 dvd.vob; the video is connected to the pad named "video" and the audio is
9121 connected to the pad named "audio":
9123 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
9127 @c man end MULTIMEDIA SOURCES