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 The expressions which specify the top left corner coordinates of the box. Default to 0.
2893 The expressions which 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 The expression which sets the thickness of the box edge. Default value is @code{3}.
2905 See below for the list of accepted constants.
2908 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
2909 following constants:
2913 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
2917 horizontal and vertical chroma subsample values. For example for the
2918 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2922 The input width and height.
2925 The input sample aspect ratio.
2929 The x and y offset coordinates where the box is drawn.
2933 The width and height of the drawn box.
2936 The thickness of the drawn box.
2938 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
2939 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
2943 @subsection Examples
2947 Draw a black box around the edge of the input image:
2953 Draw a box with color red and an opacity of 50%:
2955 drawbox=10:20:200:60:red@@0.5
2958 The previous example can be specified as:
2960 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2964 Fill the box with pink color:
2966 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2970 Draw a 2-pixel red 2.40:1 mask:
2972 drawbox=x=-t:y=0.5*(ih-iw/2.4)-t:w=iw+t*2:h=iw/2.4+t*2:t=2:c=red
2978 Draw a grid on the input image.
2980 This filter accepts the following options:
2985 The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
2989 The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
2990 input width and height, respectively, minus @code{thickness}, so image gets
2991 framed. Default to 0.
2994 Specify the color of the grid, it can be the name of a color
2995 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2996 value @code{invert} is used, the grid color is the same as the
2997 video with inverted luma.
2998 Note that you can append opacity value (in range of 0.0 - 1.0)
2999 to color name after @@ sign.
3002 The expression which sets the thickness of the grid line. Default value is @code{1}.
3004 See below for the list of accepted constants.
3007 The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the
3008 following constants:
3012 The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}.
3016 horizontal and vertical chroma subsample values. For example for the
3017 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3021 The input grid cell width and height.
3024 The input sample aspect ratio.
3028 The x and y coordinates of some point of grid intersection (meant to configure offset).
3032 The width and height of the drawn cell.
3035 The thickness of the drawn cell.
3037 These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to
3038 each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}.
3042 @subsection Examples
3046 Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%:
3048 drawgrid=width=100:height=100:thickness=2:color=red@@0.5
3052 Draw a white 3x3 grid with an opacity of 50%:
3054 drawgrid=w=iw/3:h=ih/3:t=2:c=white@@0.5
3061 Draw text string or text from specified file on top of video using the
3062 libfreetype library.
3064 To enable compilation of this filter you need to configure FFmpeg with
3065 @code{--enable-libfreetype}.
3069 The description of the accepted parameters follows.
3074 Used to draw a box around text using background color.
3075 Value should be either 1 (enable) or 0 (disable).
3076 The default value of @var{box} is 0.
3079 The color to be used for drawing box around text.
3080 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
3081 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
3082 The default value of @var{boxcolor} is "white".
3085 Set an expression which specifies if the text should be drawn. If the
3086 expression evaluates to 0, the text is not drawn. This is useful for
3087 specifying that the text should be drawn only when specific conditions
3090 Default value is "1".
3092 See below for the list of accepted constants and functions.
3095 Select how the @var{text} is expanded. Can be either @code{none},
3096 @code{strftime} (deprecated) or
3097 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
3101 If true, check and fix text coords to avoid clipping.
3104 The color to be used for drawing fonts.
3105 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
3106 (e.g. "0xff000033"), possibly followed by an alpha specifier.
3107 The default value of @var{fontcolor} is "black".
3110 The font file to be used for drawing text. Path must be included.
3111 This parameter is mandatory.
3114 The font size to be used for drawing text.
3115 The default value of @var{fontsize} is 16.
3118 Flags to be used for loading the fonts.
3120 The flags map the corresponding flags supported by libfreetype, and are
3121 a combination of the following values:
3128 @item vertical_layout
3129 @item force_autohint
3132 @item ignore_global_advance_width
3134 @item ignore_transform
3140 Default value is "render".
3142 For more information consult the documentation for the FT_LOAD_*
3146 The color to be used for drawing a shadow behind the drawn text. It
3147 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
3148 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
3149 The default value of @var{shadowcolor} is "black".
3153 The x and y offsets for the text shadow position with respect to the
3154 position of the text. They can be either positive or negative
3155 values. Default value for both is "0".
3158 The starting frame number for the n/frame_num variable. The default value
3162 The size in number of spaces to use for rendering the tab.
3166 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
3167 format. It can be used with or without text parameter. @var{timecode_rate}
3168 option must be specified.
3170 @item timecode_rate, rate, r
3171 Set the timecode frame rate (timecode only).
3174 The text string to be drawn. The text must be a sequence of UTF-8
3176 This parameter is mandatory if no file is specified with the parameter
3180 A text file containing text to be drawn. The text must be a sequence
3181 of UTF-8 encoded characters.
3183 This parameter is mandatory if no text string is specified with the
3184 parameter @var{text}.
3186 If both @var{text} and @var{textfile} are specified, an error is thrown.
3189 If set to 1, the @var{textfile} will be reloaded before each frame.
3190 Be sure to update it atomically, or it may be read partially, or even fail.
3194 The expressions which specify the offsets where text will be drawn
3195 within the video frame. They are relative to the top/left border of the
3198 The default value of @var{x} and @var{y} is "0".
3200 See below for the list of accepted constants and functions.
3203 The parameters for @var{x} and @var{y} are expressions containing the
3204 following constants and functions:
3208 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
3212 horizontal and vertical chroma subsample values. For example for the
3213 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3216 the height of each text line
3224 @item max_glyph_a, ascent
3225 the maximum distance from the baseline to the highest/upper grid
3226 coordinate used to place a glyph outline point, for all the rendered
3228 It is a positive value, due to the grid's orientation with the Y axis
3231 @item max_glyph_d, descent
3232 the maximum distance from the baseline to the lowest grid coordinate
3233 used to place a glyph outline point, for all the rendered glyphs.
3234 This is a negative value, due to the grid's orientation, with the Y axis
3238 maximum glyph height, that is the maximum height for all the glyphs
3239 contained in the rendered text, it is equivalent to @var{ascent} -
3243 maximum glyph width, that is the maximum width for all the glyphs
3244 contained in the rendered text
3247 the number of input frame, starting from 0
3249 @item rand(min, max)
3250 return a random number included between @var{min} and @var{max}
3253 input sample aspect ratio
3256 timestamp expressed in seconds, NAN if the input timestamp is unknown
3259 the height of the rendered text
3262 the width of the rendered text
3266 the x and y offset coordinates where the text is drawn.
3268 These parameters allow the @var{x} and @var{y} expressions to refer
3269 each other, so you can for example specify @code{y=x/dar}.
3272 If libavfilter was built with @code{--enable-fontconfig}, then
3273 @option{fontfile} can be a fontconfig pattern or omitted.
3275 @anchor{drawtext_expansion}
3276 @subsection Text expansion
3278 If @option{expansion} is set to @code{strftime},
3279 the filter recognizes strftime() sequences in the provided text and
3280 expands them accordingly. Check the documentation of strftime(). This
3281 feature is deprecated.
3283 If @option{expansion} is set to @code{none}, the text is printed verbatim.
3285 If @option{expansion} is set to @code{normal} (which is the default),
3286 the following expansion mechanism is used.
3288 The backslash character '\', followed by any character, always expands to
3289 the second character.
3291 Sequence of the form @code{%@{...@}} are expanded. The text between the
3292 braces is a function name, possibly followed by arguments separated by ':'.
3293 If the arguments contain special characters or delimiters (':' or '@}'),
3294 they should be escaped.
3296 Note that they probably must also be escaped as the value for the
3297 @option{text} option in the filter argument string and as the filter
3298 argument in the filtergraph description, and possibly also for the shell,
3299 that makes up to four levels of escaping; using a text file avoids these
3302 The following functions are available:
3307 The expression evaluation result.
3309 It must take one argument specifying the expression to be evaluated,
3310 which accepts the same constants and functions as the @var{x} and
3311 @var{y} values. Note that not all constants should be used, for
3312 example the text size is not known when evaluating the expression, so
3313 the constants @var{text_w} and @var{text_h} will have an undefined
3317 The time at which the filter is running, expressed in UTC.
3318 It can accept an argument: a strftime() format string.
3321 The time at which the filter is running, expressed in the local time zone.
3322 It can accept an argument: a strftime() format string.
3325 The frame number, starting from 0.
3328 A 1 character description of the current picture type.
3331 The timestamp of the current frame, in seconds, with microsecond accuracy.
3335 @subsection Examples
3339 Draw "Test Text" with font FreeSerif, using the default values for the
3340 optional parameters.
3343 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
3347 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
3348 and y=50 (counting from the top-left corner of the screen), text is
3349 yellow with a red box around it. Both the text and the box have an
3353 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
3354 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
3357 Note that the double quotes are not necessary if spaces are not used
3358 within the parameter list.
3361 Show the text at the center of the video frame:
3363 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
3367 Show a text line sliding from right to left in the last row of the video
3368 frame. The file @file{LONG_LINE} is assumed to contain a single line
3371 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
3375 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
3377 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
3381 Draw a single green letter "g", at the center of the input video.
3382 The glyph baseline is placed at half screen height.
3384 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
3388 Show text for 1 second every 3 seconds:
3390 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
3394 Use fontconfig to set the font. Note that the colons need to be escaped.
3396 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
3400 Print the date of a real-time encoding (see strftime(3)):
3402 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
3407 For more information about libfreetype, check:
3408 @url{http://www.freetype.org/}.
3410 For more information about fontconfig, check:
3411 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3415 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3417 The filter accepts the following options:
3422 Set low and high threshold values used by the Canny thresholding
3425 The high threshold selects the "strong" edge pixels, which are then
3426 connected through 8-connectivity with the "weak" edge pixels selected
3427 by the low threshold.
3429 @var{low} and @var{high} threshold values must be choosen in the range
3430 [0,1], and @var{low} should be lesser or equal to @var{high}.
3432 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3438 edgedetect=low=0.1:high=0.4
3441 @section extractplanes
3443 Extract color channel components from input video stream into
3444 separate grayscale video streams.
3446 The filter accepts the following option:
3450 Set plane(s) to extract.
3452 Available values for planes are:
3463 Choosing planes not available in the input will result in an error.
3464 That means you cannot select @code{r}, @code{g}, @code{b} planes
3465 with @code{y}, @code{u}, @code{v} planes at same time.
3468 @subsection Examples
3472 Extract luma, u and v color channel component from input video frame
3473 into 3 grayscale outputs:
3475 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
3481 Apply fade-in/out effect to input video.
3483 This filter accepts the following options:
3487 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3489 Default is @code{in}.
3491 @item start_frame, s
3492 Specify the number of the start frame for starting to apply the fade
3493 effect. Default is 0.
3496 The number of frames for which the fade effect has to last. At the end of the
3497 fade-in effect the output video will have the same intensity as the input video,
3498 at the end of the fade-out transition the output video will be completely black.
3502 If set to 1, fade only alpha channel, if one exists on the input.
3505 @item start_time, st
3506 Specify the timestamp (in seconds) of the frame to start to apply the fade
3507 effect. If both start_frame and start_time are specified, the fade will start at
3508 whichever comes last. Default is 0.
3511 The number of seconds for which the fade effect has to last. At the end of the
3512 fade-in effect the output video will have the same intensity as the input video,
3513 at the end of the fade-out transition the output video will be completely black.
3514 If both duration and nb_frames are specified, duration is used. Default is 0.
3517 @subsection Examples
3521 Fade in first 30 frames of video:
3526 The command above is equivalent to:
3532 Fade out last 45 frames of a 200-frame video:
3535 fade=type=out:start_frame=155:nb_frames=45
3539 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
3541 fade=in:0:25, fade=out:975:25
3545 Make first 5 frames black, then fade in from frame 5-24:
3551 Fade in alpha over first 25 frames of video:
3553 fade=in:0:25:alpha=1
3557 Make first 5.5 seconds black, then fade in for 0.5 seconds:
3559 fade=t=in:st=5.5:d=0.5
3566 Extract a single field from an interlaced image using stride
3567 arithmetic to avoid wasting CPU time. The output frames are marked as
3570 The filter accepts the following options:
3574 Specify whether to extract the top (if the value is @code{0} or
3575 @code{top}) or the bottom field (if the value is @code{1} or
3581 Field matching filter for inverse telecine. It is meant to reconstruct the
3582 progressive frames from a telecined stream. The filter does not drop duplicated
3583 frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be
3584 followed by a decimation filter such as @ref{decimate} in the filtergraph.
3586 The separation of the field matching and the decimation is notably motivated by
3587 the possibility of inserting a de-interlacing filter fallback between the two.
3588 If the source has mixed telecined and real interlaced content,
3589 @code{fieldmatch} will not be able to match fields for the interlaced parts.
3590 But these remaining combed frames will be marked as interlaced, and thus can be
3591 de-interlaced by a later filter such as @ref{yadif} before decimation.
3593 In addition to the various configuration options, @code{fieldmatch} can take an
3594 optional second stream, activated through the @option{ppsrc} option. If
3595 enabled, the frames reconstruction will be based on the fields and frames from
3596 this second stream. This allows the first input to be pre-processed in order to
3597 help the various algorithms of the filter, while keeping the output lossless
3598 (assuming the fields are matched properly). Typically, a field-aware denoiser,
3599 or brightness/contrast adjustments can help.
3601 Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
3602 and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
3603 which @code{fieldmatch} is based on. While the semantic and usage are very
3604 close, some behaviour and options names can differ.
3606 The filter accepts the following options:
3610 Specify the assumed field order of the input stream. Available values are:
3614 Auto detect parity (use FFmpeg's internal parity value).
3616 Assume bottom field first.
3618 Assume top field first.
3621 Note that it is sometimes recommended not to trust the parity announced by the
3624 Default value is @var{auto}.
3627 Set the matching mode or strategy to use. @option{pc} mode is the safest in the
3628 sense that it wont risk creating jerkiness due to duplicate frames when
3629 possible, but if there are bad edits or blended fields it will end up
3630 outputting combed frames when a good match might actually exist. On the other
3631 hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness,
3632 but will almost always find a good frame if there is one. The other values are
3633 all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking
3634 jerkiness and creating duplicate frames versus finding good matches in sections
3635 with bad edits, orphaned fields, blended fields, etc.
3637 More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section.
3639 Available values are:
3643 2-way matching (p/c)
3645 2-way matching, and trying 3rd match if still combed (p/c + n)
3647 2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
3649 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
3650 still combed (p/c + n + u/b)
3652 3-way matching (p/c/n)
3654 3-way matching, and trying 4th/5th matches if all 3 of the original matches are
3655 detected as combed (p/c/n + u/b)
3658 The parenthesis at the end indicate the matches that would be used for that
3659 mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or
3662 In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is
3665 Default value is @var{pc_n}.
3668 Mark the main input stream as a pre-processed input, and enable the secondary
3669 input stream as the clean source to pick the fields from. See the filter
3670 introduction for more details. It is similar to the @option{clip2} feature from
3673 Default value is @code{0} (disabled).
3676 Set the field to match from. It is recommended to set this to the same value as
3677 @option{order} unless you experience matching failures with that setting. In
3678 certain circumstances changing the field that is used to match from can have a
3679 large impact on matching performance. Available values are:
3683 Automatic (same value as @option{order}).
3685 Match from the bottom field.
3687 Match from the top field.
3690 Default value is @var{auto}.
3693 Set whether or not chroma is included during the match comparisons. In most
3694 cases it is recommended to leave this enabled. You should set this to @code{0}
3695 only if your clip has bad chroma problems such as heavy rainbowing or other
3696 artifacts. Setting this to @code{0} could also be used to speed things up at
3697 the cost of some accuracy.
3699 Default value is @code{1}.
3703 These define an exclusion band which excludes the lines between @option{y0} and
3704 @option{y1} from being included in the field matching decision. An exclusion
3705 band can be used to ignore subtitles, a logo, or other things that may
3706 interfere with the matching. @option{y0} sets the starting scan line and
3707 @option{y1} sets the ending line; all lines in between @option{y0} and
3708 @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting
3709 @option{y0} and @option{y1} to the same value will disable the feature.
3710 @option{y0} and @option{y1} defaults to @code{0}.
3713 Set the scene change detection threshold as a percentage of maximum change on
3714 the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change
3715 detection is only relevant in case @option{combmatch}=@var{sc}. The range for
3716 @option{scthresh} is @code{[0.0, 100.0]}.
3718 Default value is @code{12.0}.
3721 When @option{combatch} is not @var{none}, @code{fieldmatch} will take into
3722 account the combed scores of matches when deciding what match to use as the
3723 final match. Available values are:
3727 No final matching based on combed scores.
3729 Combed scores are only used when a scene change is detected.
3731 Use combed scores all the time.
3734 Default is @var{sc}.
3737 Force @code{fieldmatch} to calculate the combed metrics for certain matches and
3738 print them. This setting is known as @option{micout} in TFM/VFM vocabulary.
3739 Available values are:
3743 No forced calculation.
3745 Force p/c/n calculations.
3747 Force p/c/n/u/b calculations.
3750 Default value is @var{none}.
3753 This is the area combing threshold used for combed frame detection. This
3754 essentially controls how "strong" or "visible" combing must be to be detected.
3755 Larger values mean combing must be more visible and smaller values mean combing
3756 can be less visible or strong and still be detected. Valid settings are from
3757 @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will
3758 be detected as combed). This is basically a pixel difference value. A good
3759 range is @code{[8, 12]}.
3761 Default value is @code{9}.
3764 Sets whether or not chroma is considered in the combed frame decision. Only
3765 disable this if your source has chroma problems (rainbowing, etc.) that are
3766 causing problems for the combed frame detection with chroma enabled. Actually,
3767 using @option{chroma}=@var{0} is usually more reliable, except for the case
3768 where there is chroma only combing in the source.
3770 Default value is @code{0}.
3774 Respectively set the x-axis and y-axis size of the window used during combed
3775 frame detection. This has to do with the size of the area in which
3776 @option{combpel} pixels are required to be detected as combed for a frame to be
3777 declared combed. See the @option{combpel} parameter description for more info.
3778 Possible values are any number that is a power of 2 starting at 4 and going up
3781 Default value is @code{16}.
3784 The number of combed pixels inside any of the @option{blocky} by
3785 @option{blockx} size blocks on the frame for the frame to be detected as
3786 combed. While @option{cthresh} controls how "visible" the combing must be, this
3787 setting controls "how much" combing there must be in any localized area (a
3788 window defined by the @option{blockx} and @option{blocky} settings) on the
3789 frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at
3790 which point no frames will ever be detected as combed). This setting is known
3791 as @option{MI} in TFM/VFM vocabulary.
3793 Default value is @code{80}.
3796 @anchor{p/c/n/u/b meaning}
3797 @subsection p/c/n/u/b meaning
3799 @subsubsection p/c/n
3801 We assume the following telecined stream:
3804 Top fields: 1 2 2 3 4
3805 Bottom fields: 1 2 3 4 4
3808 The numbers correspond to the progressive frame the fields relate to. Here, the
3809 first two frames are progressive, the 3rd and 4th are combed, and so on.
3811 When @code{fieldmatch} is configured to run a matching from bottom
3812 (@option{field}=@var{bottom}) this is how this input stream get transformed:
3817 B 1 2 3 4 4 <-- matching reference
3826 As a result of the field matching, we can see that some frames get duplicated.
3827 To perform a complete inverse telecine, you need to rely on a decimation filter
3828 after this operation. See for instance the @ref{decimate} filter.
3830 The same operation now matching from top fields (@option{field}=@var{top})
3835 T 1 2 2 3 4 <-- matching reference
3845 In these examples, we can see what @var{p}, @var{c} and @var{n} mean;
3846 basically, they refer to the frame and field of the opposite parity:
3849 @item @var{p} matches the field of the opposite parity in the previous frame
3850 @item @var{c} matches the field of the opposite parity in the current frame
3851 @item @var{n} matches the field of the opposite parity in the next frame
3856 The @var{u} and @var{b} matching are a bit special in the sense that they match
3857 from the opposite parity flag. In the following examples, we assume that we are
3858 currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
3859 'x' is placed above and below each matched fields.
3861 With bottom matching (@option{field}=@var{bottom}):
3866 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
3867 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
3875 With top matching (@option{field}=@var{top}):
3880 Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
3881 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
3889 @subsection Examples
3891 Simple IVTC of a top field first telecined stream:
3893 fieldmatch=order=tff:combmatch=none, decimate
3896 Advanced IVTC, with fallback on @ref{yadif} for still combed frames:
3898 fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
3903 Transform the field order of the input video.
3905 This filter accepts the following options:
3910 Output field order. Valid values are @var{tff} for top field first or @var{bff}
3911 for bottom field first.
3914 Default value is @samp{tff}.
3916 Transformation is achieved by shifting the picture content up or down
3917 by one line, and filling the remaining line with appropriate picture content.
3918 This method is consistent with most broadcast field order converters.
3920 If the input video is not flagged as being interlaced, or it is already
3921 flagged as being of the required output field order then this filter does
3922 not alter the incoming video.
3924 This filter is very useful when converting to or from PAL DV material,
3925 which is bottom field first.
3929 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
3934 Buffer input images and send them when they are requested.
3936 This filter is mainly useful when auto-inserted by the libavfilter
3939 The filter does not take parameters.
3944 Convert the input video to one of the specified pixel formats.
3945 Libavfilter will try to pick one that is supported for the input to
3948 This filter accepts the following parameters:
3952 A '|'-separated list of pixel format names, for example
3953 "pix_fmts=yuv420p|monow|rgb24".
3957 @subsection Examples
3961 Convert the input video to the format @var{yuv420p}
3963 format=pix_fmts=yuv420p
3966 Convert the input video to any of the formats in the list
3968 format=pix_fmts=yuv420p|yuv444p|yuv410p
3974 Convert the video to specified constant frame rate by duplicating or dropping
3975 frames as necessary.
3977 This filter accepts the following named parameters:
3981 Desired output frame rate. The default is @code{25}.
3986 Possible values are:
3989 zero round towards 0
3993 round towards -infinity
3995 round towards +infinity
3999 The default is @code{near}.
4003 Alternatively, the options can be specified as a flat string:
4004 @var{fps}[:@var{round}].
4006 See also the @ref{setpts} filter.
4008 @subsection Examples
4012 A typical usage in order to set the fps to 25:
4018 Sets the fps to 24, using abbreviation and rounding method to round to nearest:
4020 fps=fps=film:round=near
4026 Select one frame every N-th frame.
4028 This filter accepts the following option:
4031 Select frame after every @code{step} frames.
4032 Allowed values are positive integers higher than 0. Default value is @code{1}.
4038 Apply a frei0r effect to the input video.
4040 To enable compilation of this filter you need to install the frei0r
4041 header and configure FFmpeg with @code{--enable-frei0r}.
4043 This filter accepts the following options:
4048 The name to the frei0r effect to load. If the environment variable
4049 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
4050 directories specified by the colon separated list in @env{FREIOR_PATH},
4051 otherwise in the standard frei0r paths, which are in this order:
4052 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
4053 @file{/usr/lib/frei0r-1/}.
4056 A '|'-separated list of parameters to pass to the frei0r effect.
4060 A frei0r effect parameter can be a boolean (whose values are specified
4061 with "y" and "n"), a double, a color (specified by the syntax
4062 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
4063 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
4064 description), a position (specified by the syntax @var{X}/@var{Y},
4065 @var{X} and @var{Y} being float numbers) and a string.
4067 The number and kind of parameters depend on the loaded effect. If an
4068 effect parameter is not specified the default value is set.
4070 @subsection Examples
4074 Apply the distort0r effect, set the first two double parameters:
4076 frei0r=filter_name=distort0r:filter_params=0.5|0.01
4080 Apply the colordistance effect, take a color as first parameter:
4082 frei0r=colordistance:0.2/0.3/0.4
4083 frei0r=colordistance:violet
4084 frei0r=colordistance:0x112233
4088 Apply the perspective effect, specify the top left and top right image
4091 frei0r=perspective:0.2/0.2|0.8/0.2
4095 For more information see:
4096 @url{http://frei0r.dyne.org}
4100 The filter accepts the following options:
4104 Set the luminance expression.
4106 Set the chrominance blue expression.
4108 Set the chrominance red expression.
4110 Set the alpha expression.
4112 Set the red expression.
4114 Set the green expression.
4116 Set the blue expression.
4119 The colorspace is selected according to the specified options. If one
4120 of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr}
4121 options is specified, the filter will automatically select a YCbCr
4122 colorspace. If one of the @option{red_expr}, @option{green_expr}, or
4123 @option{blue_expr} options is specified, it will select an RGB
4126 If one of the chrominance expression is not defined, it falls back on the other
4127 one. If no alpha expression is specified it will evaluate to opaque value.
4128 If none of chrominance expressions are specified, they will evaluate
4129 to the luminance expression.
4131 The expressions can use the following variables and functions:
4135 The sequential number of the filtered frame, starting from @code{0}.
4139 The coordinates of the current sample.
4143 The width and height of the image.
4147 Width and height scale depending on the currently filtered plane. It is the
4148 ratio between the corresponding luma plane number of pixels and the current
4149 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
4150 @code{0.5,0.5} for chroma planes.
4153 Time of the current frame, expressed in seconds.
4156 Return the value of the pixel at location (@var{x},@var{y}) of the current
4160 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
4164 Return the value of the pixel at location (@var{x},@var{y}) of the
4165 blue-difference chroma plane. Return 0 if there is no such plane.
4168 Return the value of the pixel at location (@var{x},@var{y}) of the
4169 red-difference chroma plane. Return 0 if there is no such plane.
4174 Return the value of the pixel at location (@var{x},@var{y}) of the
4175 red/green/blue component. Return 0 if there is no such component.
4178 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
4179 plane. Return 0 if there is no such plane.
4182 For functions, if @var{x} and @var{y} are outside the area, the value will be
4183 automatically clipped to the closer edge.
4185 @subsection Examples
4189 Flip the image horizontally:
4195 Generate a bidimensional sine wave, with angle @code{PI/3} and a
4196 wavelength of 100 pixels:
4198 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
4202 Generate a fancy enigmatic moving light:
4204 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
4208 Generate a quick emboss effect:
4210 format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
4214 Modify RGB components depending on pixel position:
4216 geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
4222 Fix the banding artifacts that are sometimes introduced into nearly flat
4223 regions by truncation to 8bit color depth.
4224 Interpolate the gradients that should go where the bands are, and
4227 This filter is designed for playback only. Do not use it prior to
4228 lossy compression, because compression tends to lose the dither and
4229 bring back the bands.
4231 This filter accepts the following options:
4236 The maximum amount by which the filter will change any one pixel. Also the
4237 threshold for detecting nearly flat regions. Acceptable values range from .51 to
4238 64, default value is 1.2, out-of-range values will be clipped to the valid
4242 The neighborhood to fit the gradient to. A larger radius makes for smoother
4243 gradients, but also prevents the filter from modifying the pixels near detailed
4244 regions. Acceptable values are 8-32, default value is 16, out-of-range values
4245 will be clipped to the valid range.
4249 Alternatively, the options can be specified as a flat string:
4250 @var{strength}[:@var{radius}]
4252 @subsection Examples
4256 Apply the filter with a @code{3.5} strength and radius of @code{8}:
4262 Specify radius, omitting the strength (which will fall-back to the default
4273 Apply a Hald CLUT to a video stream.
4275 First input is the video stream to process, and second one is the Hald CLUT.
4276 The Hald CLUT input can be a simple picture or a complete video stream.
4278 The filter accepts the following options:
4282 Force termination when the shortest input terminates. Default is @code{0}.
4284 Continue applying the last CLUT after the end of the stream. A value of
4285 @code{0} disable the filter after the last frame of the CLUT is reached.
4286 Default is @code{1}.
4289 @code{haldclut} also has the same interpolation options as @ref{lut3d} (both
4290 filters share the same internals).
4292 More information about the Hald CLUT can be found on Eskil Steenberg's website
4293 (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}.
4295 @subsection Workflow examples
4297 @subsubsection Hald CLUT video stream
4299 Generate an identity Hald CLUT stream altered with various effects:
4301 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
4304 Note: make sure you use a lossless codec.
4306 Then use it with @code{haldclut} to apply it on some random stream:
4308 ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
4311 The Hald CLUT will be applied to the 10 first seconds (duration of
4312 @file{clut.nut}), then the latest picture of that CLUT stream will be applied
4313 to the remaining frames of the @code{mandelbrot} stream.
4315 @subsubsection Hald CLUT with preview
4317 A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by
4318 @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the
4319 biggest possible square starting at the top left of the picture. The remaining
4320 padding pixels (bottom or right) will be ignored. This area can be used to add
4321 a preview of the Hald CLUT.
4323 Typically, the following generated Hald CLUT will be supported by the
4324 @code{haldclut} filter:
4327 ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "
4328 pad=iw+320 [padded_clut];
4329 smptebars=s=320x256, split [a][b];
4330 [padded_clut][a] overlay=W-320:h, curves=color_negative [main];
4331 [main][b] overlay=W-320" -frames:v 1 clut.png
4334 It contains the original and a preview of the effect of the CLUT: SMPTE color
4335 bars are displayed on the right-top, and below the same color bars processed by
4338 Then, the effect of this Hald CLUT can be visualized with:
4340 ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
4345 Flip the input video horizontally.
4347 For example to horizontally flip the input video with @command{ffmpeg}:
4349 ffmpeg -i in.avi -vf "hflip" out.avi
4353 This filter applies a global color histogram equalization on a
4356 It can be used to correct video that has a compressed range of pixel
4357 intensities. The filter redistributes the pixel intensities to
4358 equalize their distribution across the intensity range. It may be
4359 viewed as an "automatically adjusting contrast filter". This filter is
4360 useful only for correcting degraded or poorly captured source
4363 The filter accepts the following options:
4367 Determine the amount of equalization to be applied. As the strength
4368 is reduced, the distribution of pixel intensities more-and-more
4369 approaches that of the input frame. The value must be a float number
4370 in the range [0,1] and defaults to 0.200.
4373 Set the maximum intensity that can generated and scale the output
4374 values appropriately. The strength should be set as desired and then
4375 the intensity can be limited if needed to avoid washing-out. The value
4376 must be a float number in the range [0,1] and defaults to 0.210.
4379 Set the antibanding level. If enabled the filter will randomly vary
4380 the luminance of output pixels by a small amount to avoid banding of
4381 the histogram. Possible values are @code{none}, @code{weak} or
4382 @code{strong}. It defaults to @code{none}.
4387 Compute and draw a color distribution histogram for the input video.
4389 The computed histogram is a representation of distribution of color components
4392 The filter accepts the following options:
4398 It accepts the following values:
4401 standard histogram that display color components distribution in an image.
4402 Displays color graph for each color component. Shows distribution
4403 of the Y, U, V, A or G, B, R components, depending on input format,
4404 in current frame. Bellow each graph is color component scale meter.
4407 chroma values in vectorscope, if brighter more such chroma values are
4408 distributed in an image.
4409 Displays chroma values (U/V color placement) in two dimensional graph
4410 (which is called a vectorscope). It can be used to read of the hue and
4411 saturation of the current frame. At a same time it is a histogram.
4412 The whiter a pixel in the vectorscope, the more pixels of the input frame
4413 correspond to that pixel (that is the more pixels have this chroma value).
4414 The V component is displayed on the horizontal (X) axis, with the leftmost
4415 side being V = 0 and the rightmost side being V = 255.
4416 The U component is displayed on the vertical (Y) axis, with the top
4417 representing U = 0 and the bottom representing U = 255.
4419 The position of a white pixel in the graph corresponds to the chroma value
4420 of a pixel of the input clip. So the graph can be used to read of the
4421 hue (color flavor) and the saturation (the dominance of the hue in the color).
4422 As the hue of a color changes, it moves around the square. At the center of
4423 the square, the saturation is zero, which means that the corresponding pixel
4424 has no color. If you increase the amount of a specific color, while leaving
4425 the other colors unchanged, the saturation increases, and you move towards
4426 the edge of the square.
4429 chroma values in vectorscope, similar as @code{color} but actual chroma values
4433 per row/column color component graph. In row mode graph in the left side represents
4434 color component value 0 and right side represents value = 255. In column mode top
4435 side represents color component value = 0 and bottom side represents value = 255.
4437 Default value is @code{levels}.
4440 Set height of level in @code{levels}. Default value is @code{200}.
4441 Allowed range is [50, 2048].
4444 Set height of color scale in @code{levels}. Default value is @code{12}.
4445 Allowed range is [0, 40].
4448 Set step for @code{waveform} mode. Smaller values are useful to find out how much
4449 of same luminance values across input rows/columns are distributed.
4450 Default value is @code{10}. Allowed range is [1, 255].
4453 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
4454 Default is @code{row}.
4457 Set display mode for @code{waveform} and @code{levels}.
4458 It accepts the following values:
4461 Display separate graph for the color components side by side in
4462 @code{row} waveform mode or one below other in @code{column} waveform mode
4463 for @code{waveform} histogram mode. For @code{levels} histogram mode
4464 per color component graphs are placed one bellow other.
4466 This display mode in @code{waveform} histogram mode makes it easy to spot
4467 color casts in the highlights and shadows of an image, by comparing the
4468 contours of the top and the bottom of each waveform.
4469 Since whites, grays, and blacks are characterized by
4470 exactly equal amounts of red, green, and blue, neutral areas of the
4471 picture should display three waveforms of roughly equal width/height.
4472 If not, the correction is easy to make by making adjustments to level the
4476 Presents information that's identical to that in the @code{parade}, except
4477 that the graphs representing color components are superimposed directly
4480 This display mode in @code{waveform} histogram mode can make it easier to spot
4481 the relative differences or similarities in overlapping areas of the color
4482 components that are supposed to be identical, such as neutral whites, grays,
4485 Default is @code{parade}.
4488 Set mode for @code{levels}. Can be either @code{linear}, or @code{logarithmic}.
4489 Default is @code{linear}.
4492 @subsection Examples
4497 Calculate and draw histogram:
4499 ffplay -i input -vf histogram
4507 High precision/quality 3d denoise filter. This filter aims to reduce
4508 image noise producing smooth images and making still images really
4509 still. It should enhance compressibility.
4511 It accepts the following optional parameters:
4515 a non-negative float number which specifies spatial luma strength,
4518 @item chroma_spatial
4519 a non-negative float number which specifies spatial chroma strength,
4520 defaults to 3.0*@var{luma_spatial}/4.0
4523 a float number which specifies luma temporal strength, defaults to
4524 6.0*@var{luma_spatial}/4.0
4527 a float number which specifies chroma temporal strength, defaults to
4528 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
4533 Modify the hue and/or the saturation of the input.
4535 This filter accepts the following options:
4539 Specify the hue angle as a number of degrees. It accepts an expression,
4540 and defaults to "0".
4543 Specify the saturation in the [-10,10] range. It accepts an expression and
4547 Specify the hue angle as a number of radians. It accepts an
4548 expression, and defaults to "0".
4551 @option{h} and @option{H} are mutually exclusive, and can't be
4552 specified at the same time.
4554 The @option{h}, @option{H} and @option{s} option values are
4555 expressions containing the following constants:
4559 frame count of the input frame starting from 0
4562 presentation timestamp of the input frame expressed in time base units
4565 frame rate of the input video, NAN if the input frame rate is unknown
4568 timestamp expressed in seconds, NAN if the input timestamp is unknown
4571 time base of the input video
4574 @subsection Examples
4578 Set the hue to 90 degrees and the saturation to 1.0:
4584 Same command but expressing the hue in radians:
4590 Rotate hue and make the saturation swing between 0
4591 and 2 over a period of 1 second:
4593 hue="H=2*PI*t: s=sin(2*PI*t)+1"
4597 Apply a 3 seconds saturation fade-in effect starting at 0:
4602 The general fade-in expression can be written as:
4604 hue="s=min(0\, max((t-START)/DURATION\, 1))"
4608 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
4610 hue="s=max(0\, min(1\, (8-t)/3))"
4613 The general fade-out expression can be written as:
4615 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
4620 @subsection Commands
4622 This filter supports the following commands:
4627 Modify the hue and/or the saturation of the input video.
4628 The command accepts the same syntax of the corresponding option.
4630 If the specified expression is not valid, it is kept at its current
4636 Detect video interlacing type.
4638 This filter tries to detect if the input is interlaced or progressive,
4639 top or bottom field first.
4641 The filter accepts the following options:
4645 Set interlacing threshold.
4647 Set progressive threshold.
4652 Deinterleave or interleave fields.
4654 This filter allows to process interlaced images fields without
4655 deinterlacing them. Deinterleaving splits the input frame into 2
4656 fields (so called half pictures). Odd lines are moved to the top
4657 half of the output image, even lines to the bottom half.
4658 You can process (filter) them independently and then re-interleave them.
4660 The filter accepts the following options:
4664 @item chroma_mode, c
4666 Available values for @var{luma_mode}, @var{chroma_mode} and
4667 @var{alpha_mode} are:
4673 @item deinterleave, d
4674 Deinterleave fields, placing one above the other.
4677 Interleave fields. Reverse the effect of deinterleaving.
4679 Default value is @code{none}.
4682 @item chroma_swap, cs
4683 @item alpha_swap, as
4684 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
4689 Simple interlacing filter from progressive contents. This interleaves upper (or
4690 lower) lines from odd frames with lower (or upper) lines from even frames,
4691 halving the frame rate and preserving image height.
4694 Original Original New Frame
4695 Frame 'j' Frame 'j+1' (tff)
4696 ========== =========== ==================
4697 Line 0 --------------------> Frame 'j' Line 0
4698 Line 1 Line 1 ----> Frame 'j+1' Line 1
4699 Line 2 ---------------------> Frame 'j' Line 2
4700 Line 3 Line 3 ----> Frame 'j+1' Line 3
4702 New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
4705 It accepts the following optional parameters:
4709 determines whether the interlaced frame is taken from the even (tff - default)
4710 or odd (bff) lines of the progressive frame.
4713 Enable (default) or disable the vertical lowpass filter to avoid twitter
4714 interlacing and reduce moire patterns.
4719 Deinterlace input video by applying Donald Graft's adaptive kernel
4720 deinterling. Work on interlaced parts of a video to produce
4723 The description of the accepted parameters follows.
4727 Set the threshold which affects the filter's tolerance when
4728 determining if a pixel line must be processed. It must be an integer
4729 in the range [0,255] and defaults to 10. A value of 0 will result in
4730 applying the process on every pixels.
4733 Paint pixels exceeding the threshold value to white if set to 1.
4737 Set the fields order. Swap fields if set to 1, leave fields alone if
4741 Enable additional sharpening if set to 1. Default is 0.
4744 Enable twoway sharpening if set to 1. Default is 0.
4747 @subsection Examples
4751 Apply default values:
4753 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
4757 Enable additional sharpening:
4763 Paint processed pixels in white:
4772 Apply a 3D LUT to an input video.
4774 The filter accepts the following options:
4778 Set the 3D LUT file name.
4780 Currently supported formats:
4792 Select interpolation mode.
4794 Available values are:
4798 Use values from the nearest defined point.
4800 Interpolate values using the 8 points defining a cube.
4802 Interpolate values using a tetrahedron.
4806 @section lut, lutrgb, lutyuv
4808 Compute a look-up table for binding each pixel component input value
4809 to an output value, and apply it to input video.
4811 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
4812 to an RGB input video.
4814 These filters accept the following options:
4817 set first pixel component expression
4819 set second pixel component expression
4821 set third pixel component expression
4823 set fourth pixel component expression, corresponds to the alpha component
4826 set red component expression
4828 set green component expression
4830 set blue component expression
4832 alpha component expression
4835 set Y/luminance component expression
4837 set U/Cb component expression
4839 set V/Cr component expression
4842 Each of them specifies the expression to use for computing the lookup table for
4843 the corresponding pixel component values.
4845 The exact component associated to each of the @var{c*} options depends on the
4848 The @var{lut} filter requires either YUV or RGB pixel formats in input,
4849 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
4851 The expressions can contain the following constants and functions:
4856 the input width and height
4859 input value for the pixel component
4862 the input value clipped in the @var{minval}-@var{maxval} range
4865 maximum value for the pixel component
4868 minimum value for the pixel component
4871 the negated value for the pixel component value clipped in the
4872 @var{minval}-@var{maxval} range , it corresponds to the expression
4873 "maxval-clipval+minval"
4876 the computed value in @var{val} clipped in the
4877 @var{minval}-@var{maxval} range
4879 @item gammaval(gamma)
4880 the computed gamma correction value of the pixel component value
4881 clipped in the @var{minval}-@var{maxval} range, corresponds to the
4883 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
4887 All expressions default to "val".
4889 @subsection Examples
4895 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
4896 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
4899 The above is the same as:
4901 lutrgb="r=negval:g=negval:b=negval"
4902 lutyuv="y=negval:u=negval:v=negval"
4912 Remove chroma components, turns the video into a graytone image:
4914 lutyuv="u=128:v=128"
4918 Apply a luma burning effect:
4924 Remove green and blue components:
4930 Set a constant alpha channel value on input:
4932 format=rgba,lutrgb=a="maxval-minval/2"
4936 Correct luminance gamma by a 0.5 factor:
4938 lutyuv=y=gammaval(0.5)
4942 Discard least significant bits of luma:
4944 lutyuv=y='bitand(val, 128+64+32)'
4950 Apply motion-compensation deinterlacing.
4952 It needs one field per frame as input and must thus be used together
4953 with yadif=1/3 or equivalent.
4955 This filter accepts the following options:
4958 Set the deinterlacing mode.
4960 It accepts one of the following values:
4965 use iterative motion estimation
4967 like @samp{slow}, but use multiple reference frames.
4969 Default value is @samp{fast}.
4972 Set the picture field parity assumed for the input video. It must be
4973 one of the following values:
4977 assume top field first
4979 assume bottom field first
4982 Default value is @samp{bff}.
4985 Set per-block quantization parameter (QP) used by the internal
4988 Higher values should result in a smoother motion vector field but less
4989 optimal individual vectors. Default value is 1.
4994 Apply an MPlayer filter to the input video.
4996 This filter provides a wrapper around most of the filters of
4999 This wrapper is considered experimental. Some of the wrapped filters
5000 may not work properly and we may drop support for them, as they will
5001 be implemented natively into FFmpeg. Thus you should avoid
5002 depending on them when writing portable scripts.
5004 The filters accepts the parameters:
5005 @var{filter_name}[:=]@var{filter_params}
5007 @var{filter_name} is the name of a supported MPlayer filter,
5008 @var{filter_params} is a string containing the parameters accepted by
5011 The list of the currently supported filters follows:
5028 The parameter syntax and behavior for the listed filters are the same
5029 of the corresponding MPlayer filters. For detailed instructions check
5030 the "VIDEO FILTERS" section in the MPlayer manual.
5032 @subsection Examples
5036 Adjust gamma, brightness, contrast:
5042 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
5046 Drop frames that do not differ greatly from the previous frame in
5047 order to reduce frame rate.
5049 The main use of this filter is for very-low-bitrate encoding
5050 (e.g. streaming over dialup modem), but it could in theory be used for
5051 fixing movies that were inverse-telecined incorrectly.
5053 A description of the accepted options follows.
5057 Set the maximum number of consecutive frames which can be dropped (if
5058 positive), or the minimum interval between dropped frames (if
5059 negative). If the value is 0, the frame is dropped unregarding the
5060 number of previous sequentially dropped frames.
5067 Set the dropping threshold values.
5069 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
5070 represent actual pixel value differences, so a threshold of 64
5071 corresponds to 1 unit of difference for each pixel, or the same spread
5072 out differently over the block.
5074 A frame is a candidate for dropping if no 8x8 blocks differ by more
5075 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
5076 meaning the whole image) differ by more than a threshold of @option{lo}.
5078 Default value for @option{hi} is 64*12, default value for @option{lo} is
5079 64*5, and default value for @option{frac} is 0.33.
5087 This filter accepts an integer in input, if non-zero it negates the
5088 alpha component (if available). The default value in input is 0.
5092 Force libavfilter not to use any of the specified pixel formats for the
5093 input to the next filter.
5095 This filter accepts the following parameters:
5099 A '|'-separated list of pixel format names, for example
5100 "pix_fmts=yuv420p|monow|rgb24".
5104 @subsection Examples
5108 Force libavfilter to use a format different from @var{yuv420p} for the
5109 input to the vflip filter:
5111 noformat=pix_fmts=yuv420p,vflip
5115 Convert the input video to any of the formats not contained in the list:
5117 noformat=yuv420p|yuv444p|yuv410p
5123 Add noise on video input frame.
5125 The filter accepts the following options: