1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 In libavfilter, a filter can have multiple inputs and multiple
8 To illustrate the sorts of things that are possible, we consider the
12 input --> split ---------------------> overlay --> output
15 +-----> crop --> vflip -------+
18 This filtergraph splits the input stream in two streams, sends one
19 stream through the crop filter and the vflip filter before merging it
20 back with the other stream by overlaying it on top. You can use the
21 following command to achieve this:
24 ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT
27 The result will be that in output the top half of the video is mirrored
30 Filters in the same linear chain are separated by commas, and distinct
31 linear chains of filters are separated by semicolons. In our example,
32 @var{crop,vflip} are in one linear chain, @var{split} and
33 @var{overlay} are separately in another. The points where the linear
34 chains join are labelled by names enclosed in square brackets. In the
35 example, the split filter generates two outputs that are associated to
36 the labels @var{[main]} and @var{[tmp]}.
38 The stream sent to the second output of @var{split}, labelled as
39 @var{[tmp]}, is processed through the @var{crop} filter, which crops
40 away the lower half part of the video, and then vertically flipped. The
41 @var{overlay} filter takes in input the first unchanged output of the
42 split filter (which was labelled as @var{[main]}), and overlay on its
43 lower half the output generated by the @var{crop,vflip} filterchain.
45 Some filters take in input a list of parameters: they are specified
46 after the filter name and an equal sign, and are separated from each other
49 There exist so-called @var{source filters} that do not have an
50 audio/video input, and @var{sink filters} that will not have audio/video
53 @c man end FILTERING INTRODUCTION
56 @c man begin GRAPH2DOT
58 The @file{graph2dot} program included in the FFmpeg @file{tools}
59 directory can be used to parse a filtergraph description and issue a
60 corresponding textual representation in the dot language.
67 to see how to use @file{graph2dot}.
69 You can then pass the dot description to the @file{dot} program (from
70 the graphviz suite of programs) and obtain a graphical representation
73 For example the sequence of commands:
75 echo @var{GRAPH_DESCRIPTION} | \
76 tools/graph2dot -o graph.tmp && \
77 dot -Tpng graph.tmp -o graph.png && \
81 can be used to create and display an image representing the graph
82 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
83 a complete self-contained graph, with its inputs and outputs explicitly defined.
84 For example if your command line is of the form:
86 ffmpeg -i infile -vf scale=640:360 outfile
88 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
90 nullsrc,scale=640:360,nullsink
92 you may also need to set the @var{nullsrc} parameters and add a @var{format}
93 filter in order to simulate a specific input file.
97 @chapter Filtergraph description
98 @c man begin FILTERGRAPH DESCRIPTION
100 A filtergraph is a directed graph of connected filters. It can contain
101 cycles, and there can be multiple links between a pair of
102 filters. Each link has one input pad on one side connecting it to one
103 filter from which it takes its input, and one output pad on the other
104 side connecting it to the one filter accepting its output.
106 Each filter in a filtergraph is an instance of a filter class
107 registered in the application, which defines the features and the
108 number of input and output pads of the filter.
110 A filter with no input pads is called a "source", a filter with no
111 output pads is called a "sink".
113 @anchor{Filtergraph syntax}
114 @section Filtergraph syntax
116 A filtergraph can be represented using a textual representation, which is
117 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
118 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
119 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
120 @file{libavfilter/avfiltergraph.h}.
122 A filterchain consists of a sequence of connected filters, each one
123 connected to the previous one in the sequence. A filterchain is
124 represented by a list of ","-separated filter descriptions.
126 A filtergraph consists of a sequence of filterchains. A sequence of
127 filterchains is represented by a list of ";"-separated filterchain
130 A filter is represented by a string of the form:
131 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
133 @var{filter_name} is the name of the filter class of which the
134 described filter is an instance of, and has to be the name of one of
135 the filter classes registered in the program.
136 The name of the filter class is optionally followed by a string
139 @var{arguments} is a string which contains the parameters used to
140 initialize the filter instance. It may have one of the 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 @c man end FILTERGRAPH DESCRIPTION
272 @chapter Audio Filters
273 @c man begin AUDIO FILTERS
275 When you configure your FFmpeg build, you can disable any of the
276 existing filters using @code{--disable-filters}.
277 The configure output will show the audio filters included in your
280 Below is a description of the currently available audio filters.
284 Convert the input audio format to the specified formats.
286 The filter accepts a string of the form:
287 "@var{sample_format}:@var{channel_layout}".
289 @var{sample_format} specifies the sample format, and can be a string or the
290 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
291 suffix for a planar sample format.
293 @var{channel_layout} specifies the channel layout, and can be a string
294 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
296 The special parameter "auto", signifies that the filter will
297 automatically select the output format depending on the output filter.
303 Convert input to float, planar, stereo:
309 Convert input to unsigned 8-bit, automatically select out channel layout:
317 Apply a two-pole all-pass filter with central frequency (in Hz)
318 @var{frequency}, and filter-width @var{width}.
319 An all-pass filter changes the audio's frequency to phase relationship
320 without changing its frequency to amplitude relationship.
322 The filter accepts parameters as a list of @var{key}=@var{value}
323 pairs, separated by ":".
325 A description of the accepted parameters follows.
332 Set method to specify band-width of filter.
345 Specify the band-width of a filter in width_type units.
350 Apply a high-pass filter with 3dB point frequency.
351 The filter can be either single-pole, or double-pole (the default).
352 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
354 The filter accepts parameters as a list of @var{key}=@var{value}
355 pairs, separated by ":".
357 A description of the accepted parameters follows.
361 Set frequency in Hz. Default is 3000.
364 Set number of poles. Default is 2.
367 Set method to specify band-width of filter.
380 Specify the band-width of a filter in width_type units.
381 Applies only to double-pole filter.
382 The default is 0.707q and gives a Butterworth response.
387 Apply a low-pass filter with 3dB point frequency.
388 The filter can be either single-pole or double-pole (the default).
389 The filter roll off at 6dB per pole per octave (20dB per pole per decade).
391 The filter accepts parameters as a list of @var{key}=@var{value}
392 pairs, separated by ":".
394 A description of the accepted parameters follows.
398 Set frequency in Hz. Default is 500.
401 Set number of poles. Default is 2.
404 Set method to specify band-width of filter.
417 Specify the band-width of a filter in width_type units.
418 Applies only to double-pole filter.
419 The default is 0.707q and gives a Butterworth response.
424 Boost or cut the bass (lower) frequencies of the audio using a two-pole
425 shelving filter with a response similar to that of a standard
426 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
428 The filter accepts parameters as a list of @var{key}=@var{value}
429 pairs, separated by ":".
431 A description of the accepted parameters follows.
435 Give the gain at 0 Hz. Its useful range is about -20
436 (for a large cut) to +20 (for a large boost).
437 Beware of clipping when using a positive gain.
440 Set the filter's central frequency and so can be used
441 to extend or reduce the frequency range to be boosted or cut.
442 The default value is @code{100} Hz.
445 Set method to specify band-width of filter.
458 Determine how steep is the filter's shelf transition.
463 Boost or cut treble (upper) frequencies of the audio using a two-pole
464 shelving filter with a response similar to that of a standard
465 hi-fi's tone-controls. This is also known as shelving equalisation (EQ).
467 The filter accepts parameters as a list of @var{key}=@var{value}
468 pairs, separated by ":".
470 A description of the accepted parameters follows.
474 Give the gain at whichever is the lower of ~22 kHz and the
475 Nyquist frequency. Its useful range is about -20 (for a large cut)
476 to +20 (for a large boost). Beware of clipping when using a positive gain.
479 Set the filter's central frequency and so can be used
480 to extend or reduce the frequency range to be boosted or cut.
481 The default value is @code{3000} Hz.
484 Set method to specify band-width of filter.
497 Determine how steep is the filter's shelf transition.
502 Apply a two-pole Butterworth band-pass filter with central
503 frequency @var{frequency}, and (3dB-point) band-width width.
504 The @var{csg} option selects a constant skirt gain (peak gain = Q)
505 instead of the default: constant 0dB peak gain.
506 The filter roll off at 6dB per octave (20dB per decade).
508 The filter accepts parameters as a list of @var{key}=@var{value}
509 pairs, separated by ":".
511 A description of the accepted parameters follows.
515 Set the filter's central frequency. Default is @code{3000}.
518 Constant skirt gain if set to 1. Defaults to 0.
521 Set method to specify band-width of filter.
534 Specify the band-width of a filter in width_type units.
539 Apply a two-pole Butterworth band-reject filter with central
540 frequency @var{frequency}, and (3dB-point) band-width @var{width}.
541 The filter roll off at 6dB per octave (20dB per decade).
543 The filter accepts parameters as a list of @var{key}=@var{value}
544 pairs, separated by ":".
546 A description of the accepted parameters follows.
550 Set the filter's central frequency. Default is @code{3000}.
553 Set method to specify band-width of filter.
566 Specify the band-width of a filter in width_type units.
571 Apply a biquad IIR filter with the given coefficients.
572 Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2}
573 are the numerator and denominator coefficients respectively.
577 Apply a two-pole peaking equalisation (EQ) filter. With this
578 filter, the signal-level at and around a selected frequency can
579 be increased or decreased, whilst (unlike bandpass and bandreject
580 filters) that at all other frequencies is unchanged.
582 In order to produce complex equalisation curves, this filter can
583 be given several times, each with a different central frequency.
585 The filter accepts parameters as a list of @var{key}=@var{value}
586 pairs, separated by ":".
588 A description of the accepted parameters follows.
592 Set the filter's central frequency in Hz.
595 Set method to specify band-width of filter.
608 Specify the band-width of a filter in width_type units.
611 Set the required gain or attenuation in dB.
612 Beware of clipping when using a positive gain.
617 Apply fade-in/out effect to input audio.
619 A description of the accepted parameters follows.
623 Specify the effect type, can be either @code{in} for fade-in, or
624 @code{out} for a fade-out effect. Default is @code{in}.
626 @item start_sample, ss
627 Specify the number of the start sample for starting to apply the fade
628 effect. Default is 0.
631 Specify the number of samples for which the fade effect has to last. At
632 the end of the fade-in effect the output audio will have the same
633 volume as the input audio, at the end of the fade-out transition
634 the output audio will be silence. Default is 44100.
637 Specify time in seconds for starting to apply the fade
638 effect. Default is 0.
639 If set this option is used instead of @var{start_sample} one.
642 Specify the number of seconds for which the fade effect has to last. At
643 the end of the fade-in effect the output audio will have the same
644 volume as the input audio, at the end of the fade-out transition
645 the output audio will be silence. Default is 0.
646 If set this option is used instead of @var{nb_samples} one.
649 Set curve for fade transition.
651 It accepts the following values:
654 select triangular, linear slope (default)
656 select quarter of sine wave
658 select half of sine wave
660 select exponential sine wave
664 select inverted parabola
680 Fade in first 15 seconds of audio:
686 Fade out last 25 seconds of a 900 seconds audio:
688 afade=t=out:ss=875:d=25
695 Set output format constraints for the input audio. The framework will
696 negotiate the most appropriate format to minimize conversions.
698 The filter accepts the following named parameters:
702 A '|'-separated list of requested sample formats.
705 A '|'-separated list of requested sample rates.
707 @item channel_layouts
708 A '|'-separated list of requested channel layouts.
712 If a parameter is omitted, all values are allowed.
714 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
716 aformat=sample_fmts=u8|s16:channel_layouts=stereo
721 Merge two or more audio streams into a single multi-channel stream.
723 The filter accepts the following named options:
728 Set the number of inputs. Default is 2.
732 If the channel layouts of the inputs are disjoint, and therefore compatible,
733 the channel layout of the output will be set accordingly and the channels
734 will be reordered as necessary. If the channel layouts of the inputs are not
735 disjoint, the output will have all the channels of the first input then all
736 the channels of the second input, in that order, and the channel layout of
737 the output will be the default value corresponding to the total number of
740 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
741 is FC+BL+BR, then the output will be in 5.1, with the channels in the
742 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
743 first input, b1 is the first channel of the second input).
745 On the other hand, if both input are in stereo, the output channels will be
746 in the default order: a1, a2, b1, b2, and the channel layout will be
747 arbitrarily set to 4.0, which may or may not be the expected value.
749 All inputs must have the same sample rate, and format.
751 If inputs do not have the same duration, the output will stop with the
758 Merge two mono files into a stereo stream:
760 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
767 amovie=input.mkv:si=0 [a0];
768 amovie=input.mkv:si=1 [a1];
769 amovie=input.mkv:si=2 [a2];
770 amovie=input.mkv:si=3 [a3];
771 amovie=input.mkv:si=4 [a4];
772 amovie=input.mkv:si=5 [a5];
773 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
779 Mixes multiple audio inputs into a single output.
783 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
785 will mix 3 input audio streams to a single output with the same duration as the
786 first input and a dropout transition time of 3 seconds.
788 The filter accepts the following named parameters:
792 Number of inputs. If unspecified, it defaults to 2.
795 How to determine the end-of-stream.
799 Duration of longest input. (default)
802 Duration of shortest input.
805 Duration of first input.
809 @item dropout_transition
810 Transition time, in seconds, for volume renormalization when an input
811 stream ends. The default value is 2 seconds.
817 Pass the audio source unchanged to the output.
821 Pad the end of a audio stream with silence, this can be used together with
822 -shortest to extend audio streams to the same length as the video stream.
827 Resample the input audio to the specified parameters, using the
828 libswresample library. If none are specified then the filter will
829 automatically convert between its input and output.
831 This filter is also able to stretch/squeeze the audio data to make it match
832 the timestamps or to inject silence / cut out audio to make it match the
833 timestamps, do a combination of both or do neither.
835 The filter accepts the syntax
836 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
837 expresses a sample rate and @var{resampler_options} is a list of
838 @var{key}=@var{value} pairs, separated by ":". See the
839 ffmpeg-resampler manual for the complete list of supported options.
845 Resample the input audio to 44100Hz:
851 Stretch/squeeze samples to the given timestamps, with a maximum of 1000
852 samples per second compensation:
858 @section asetnsamples
860 Set the number of samples per each output audio frame.
862 The last output packet may contain a different number of samples, as
863 the filter will flush all the remaining samples when the input audio
866 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
871 @item nb_out_samples, n
872 Set the number of frames per each output audio frame. The number is
873 intended as the number of samples @emph{per each channel}.
874 Default value is 1024.
877 If set to 1, the filter will pad the last audio frame with zeroes, so
878 that the last frame will contain the same number of samples as the
879 previous ones. Default value is 1.
882 For example, to set the number of per-frame samples to 1234 and
883 disable padding for the last frame, use:
885 asetnsamples=n=1234:p=0
890 Show a line containing various information for each input audio frame.
891 The input audio is not modified.
893 The shown line contains a sequence of key/value pairs of the form
894 @var{key}:@var{value}.
896 A description of each shown parameter follows:
900 sequential number of the input frame, starting from 0
903 Presentation timestamp of the input frame, in time base units; the time base
904 depends on the filter input pad, and is usually 1/@var{sample_rate}.
907 presentation timestamp of the input frame in seconds
910 position of the frame in the input stream, -1 if this information in
911 unavailable and/or meaningless (for example in case of synthetic audio)
920 sample rate for the audio frame
923 number of samples (per channel) in the frame
926 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
927 the data is treated as if all the planes were concatenated.
929 @item plane_checksums
930 A list of Adler-32 checksums for each data plane.
935 Split input audio into several identical outputs.
937 The filter accepts a single parameter which specifies the number of outputs. If
938 unspecified, it defaults to 2.
942 [in] asplit [out0][out1]
945 will create two separate outputs from the same input.
947 To create 3 or more outputs, you need to specify the number of
950 [in] asplit=3 [out0][out1][out2]
954 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
956 will create 5 copies of the input audio.
961 Forward two audio streams and control the order the buffers are forwarded.
963 The argument to the filter is an expression deciding which stream should be
964 forwarded next: if the result is negative, the first stream is forwarded; if
965 the result is positive or zero, the second stream is forwarded. It can use
966 the following variables:
970 number of buffers forwarded so far on each stream
972 number of samples forwarded so far on each stream
974 current timestamp of each stream
977 The default value is @code{t1-t2}, which means to always forward the stream
978 that has a smaller timestamp.
980 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
981 input, while avoiding too much of a desynchronization:
983 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
984 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
992 The filter accepts exactly one parameter, the audio tempo. If not
993 specified then the filter will assume nominal 1.0 tempo. Tempo must
994 be in the [0.5, 2.0] range.
1000 Slow down audio to 80% tempo:
1006 To speed up audio to 125% tempo:
1014 Make audio easier to listen to on headphones.
1016 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
1017 so that when listened to on headphones the stereo image is moved from
1018 inside your head (standard for headphones) to outside and in front of
1019 the listener (standard for speakers).
1025 Mix channels with specific gain levels. The filter accepts the output
1026 channel layout followed by a set of channels definitions.
1028 This filter is also designed to remap efficiently the channels of an audio
1031 The filter accepts parameters of the form:
1032 "@var{l}:@var{outdef}:@var{outdef}:..."
1036 output channel layout or number of channels
1039 output channel specification, of the form:
1040 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
1043 output channel to define, either a channel name (FL, FR, etc.) or a channel
1044 number (c0, c1, etc.)
1047 multiplicative coefficient for the channel, 1 leaving the volume unchanged
1050 input channel to use, see out_name for details; it is not possible to mix
1051 named and numbered input channels
1054 If the `=' in a channel specification is replaced by `<', then the gains for
1055 that specification will be renormalized so that the total is 1, thus
1056 avoiding clipping noise.
1058 @subsection Mixing examples
1060 For example, if you want to down-mix from stereo to mono, but with a bigger
1061 factor for the left channel:
1063 pan=1:c0=0.9*c0+0.1*c1
1066 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
1067 7-channels surround:
1069 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
1072 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
1073 that should be preferred (see "-ac" option) unless you have very specific
1076 @subsection Remapping examples
1078 The channel remapping will be effective if, and only if:
1081 @item gain coefficients are zeroes or ones,
1082 @item only one input per channel output,
1085 If all these conditions are satisfied, the filter will notify the user ("Pure
1086 channel mapping detected"), and use an optimized and lossless method to do the
1089 For example, if you have a 5.1 source and want a stereo audio stream by
1090 dropping the extra channels:
1092 pan="stereo: c0=FL : c1=FR"
1095 Given the same source, you can also switch front left and front right channels
1096 and keep the input channel layout:
1098 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
1101 If the input is a stereo audio stream, you can mute the front left channel (and
1102 still keep the stereo channel layout) with:
1107 Still with a stereo audio stream input, you can copy the right channel in both
1108 front left and right:
1110 pan="stereo: c0=FR : c1=FR"
1113 @section silencedetect
1115 Detect silence in an audio stream.
1117 This filter logs a message when it detects that the input audio volume is less
1118 or equal to a noise tolerance value for a duration greater or equal to the
1119 minimum detected noise duration.
1121 The printed times and duration are expressed in seconds.
1123 The filter accepts the following options:
1127 Set silence duration until notification (default is 2 seconds).
1130 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
1131 specified value) or amplitude ratio. Default is -60dB, or 0.001.
1134 @subsection Examples
1138 Detect 5 seconds of silence with -50dB noise tolerance:
1140 silencedetect=n=-50dB:d=5
1144 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
1145 tolerance in @file{silence.mp3}:
1147 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
1152 Synchronize audio data with timestamps by squeezing/stretching it and/or
1153 dropping samples/adding silence when needed.
1155 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
1157 The filter accepts the following named parameters:
1161 Enable stretching/squeezing the data to make it match the timestamps. Disabled
1162 by default. When disabled, time gaps are covered with silence.
1165 Minimum difference between timestamps and audio data (in seconds) to trigger
1166 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
1167 this filter, try setting this parameter to 0.
1170 Maximum compensation in samples per second. Relevant only with compensate=1.
1174 Assume the first pts should be this value. The time base is 1 / sample rate.
1175 This allows for padding/trimming at the start of stream. By default, no
1176 assumption is made about the first frame's expected pts, so no padding or
1177 trimming is done. For example, this could be set to 0 to pad the beginning with
1178 silence if an audio stream starts after the video stream or to trim any samples
1179 with a negative pts due to encoder delay.
1183 @section channelsplit
1184 Split each channel in input audio stream into a separate output stream.
1186 This filter accepts the following named parameters:
1188 @item channel_layout
1189 Channel layout of the input stream. Default is "stereo".
1192 For example, assuming a stereo input MP3 file
1194 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
1196 will create an output Matroska file with two audio streams, one containing only
1197 the left channel and the other the right channel.
1199 To split a 5.1 WAV file into per-channel files
1201 ffmpeg -i in.wav -filter_complex
1202 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
1203 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
1204 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
1209 Remap input channels to new locations.
1211 This filter accepts the following named parameters:
1213 @item channel_layout
1214 Channel layout of the output stream.
1217 Map channels from input to output. The argument is a '|'-separated list of
1218 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
1219 @var{in_channel} form. @var{in_channel} can be either the name of the input
1220 channel (e.g. FL for front left) or its index in the input channel layout.
1221 @var{out_channel} is the name of the output channel or its index in the output
1222 channel layout. If @var{out_channel} is not given then it is implicitly an
1223 index, starting with zero and increasing by one for each mapping.
1226 If no mapping is present, the filter will implicitly map input channels to
1227 output channels preserving index.
1229 For example, assuming a 5.1+downmix input MOV file
1231 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
1233 will create an output WAV file tagged as stereo from the downmix channels of
1236 To fix a 5.1 WAV improperly encoded in AAC's native channel order
1238 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
1242 Join multiple input streams into one multi-channel stream.
1244 The filter accepts the following named parameters:
1248 Number of input streams. Defaults to 2.
1250 @item channel_layout
1251 Desired output channel layout. Defaults to stereo.
1254 Map channels from inputs to output. The argument is a '|'-separated list of
1255 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
1256 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
1257 can be either the name of the input channel (e.g. FL for front left) or its
1258 index in the specified input stream. @var{out_channel} is the name of the output
1262 The filter will attempt to guess the mappings when those are not specified
1263 explicitly. It does so by first trying to find an unused matching input channel
1264 and if that fails it picks the first unused input channel.
1266 E.g. to join 3 inputs (with properly set channel layouts)
1268 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
1271 To build a 5.1 output from 6 single-channel streams:
1273 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
1274 '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'
1279 Convert the audio sample format, sample rate and channel layout. This filter is
1280 not meant to be used directly.
1284 Adjust the input audio volume.
1286 The filter accepts the following named parameters. If the key of the
1287 first options is omitted, the arguments are interpreted according to
1288 the following syntax:
1290 volume=@var{volume}:@var{precision}
1296 Expresses how the audio volume will be increased or decreased.
1298 Output values are clipped to the maximum value.
1300 The output audio volume is given by the relation:
1302 @var{output_volume} = @var{volume} * @var{input_volume}
1305 Default value for @var{volume} is 1.0.
1308 Set the mathematical precision.
1310 This determines which input sample formats will be allowed, which affects the
1311 precision of the volume scaling.
1315 8-bit fixed-point; limits input sample format to U8, S16, and S32.
1317 32-bit floating-point; limits input sample format to FLT. (default)
1319 64-bit floating-point; limits input sample format to DBL.
1323 @subsection Examples
1327 Halve the input audio volume:
1331 volume=volume=-6.0206dB
1334 In all the above example the named key for @option{volume} can be
1335 omitted, for example like in:
1341 Increase input audio power by 6 decibels using fixed-point precision:
1343 volume=volume=6dB:precision=fixed
1347 @section volumedetect
1349 Detect the volume of the input video.
1351 The filter has no parameters. The input is not modified. Statistics about
1352 the volume will be printed in the log when the input stream end is reached.
1354 In particular it will show the mean volume (root mean square), maximum
1355 volume (on a per-sample basis), and the beginning of an histogram of the
1356 registered volume values (from the maximum value to a cumulated 1/1000 of
1359 All volumes are in decibels relative to the maximum PCM value.
1361 @subsection Examples
1363 Here is an excerpt of the output:
1365 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1366 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1367 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1368 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1369 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1370 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1371 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1372 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1373 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1379 The mean square energy is approximately -27 dB, or 10^-2.7.
1381 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1383 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1386 In other words, raising the volume by +4 dB does not cause any clipping,
1387 raising it by +5 dB causes clipping for 6 samples, etc.
1389 @c man end AUDIO FILTERS
1391 @chapter Audio Sources
1392 @c man begin AUDIO SOURCES
1394 Below is a description of the currently available audio sources.
1398 Buffer audio frames, and make them available to the filter chain.
1400 This source is mainly intended for a programmatic use, in particular
1401 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1403 It accepts the following mandatory parameters:
1404 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
1409 The sample rate of the incoming audio buffers.
1412 The sample format of the incoming audio buffers.
1413 Either a sample format name or its corresponging integer representation from
1414 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1416 @item channel_layout
1417 The channel layout of the incoming audio buffers.
1418 Either a channel layout name from channel_layout_map in
1419 @file{libavutil/channel_layout.c} or its corresponding integer representation
1420 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1423 The number of channels of the incoming audio buffers.
1424 If both @var{channels} and @var{channel_layout} are specified, then they
1429 @subsection Examples
1432 abuffer=44100:s16p:stereo
1435 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1436 Since the sample format with name "s16p" corresponds to the number
1437 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1445 Generate an audio signal specified by an expression.
1447 This source accepts in input one or more expressions (one for each
1448 channel), which are evaluated and used to generate a corresponding
1451 It accepts the syntax: @var{exprs}[::@var{options}].
1452 @var{exprs} is a list of expressions separated by ":", one for each
1453 separate channel. In case the @var{channel_layout} is not
1454 specified, the selected channel layout depends on the number of
1455 provided expressions.
1457 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1460 The description of the accepted options follows.
1464 @item channel_layout, c
1465 Set the channel layout. The number of channels in the specified layout
1466 must be equal to the number of specified expressions.
1469 Set the minimum duration of the sourced audio. See the function
1470 @code{av_parse_time()} for the accepted format.
1471 Note that the resulting duration may be greater than the specified
1472 duration, as the generated audio is always cut at the end of a
1475 If not specified, or the expressed duration is negative, the audio is
1476 supposed to be generated forever.
1479 Set the number of samples per channel per each output frame,
1482 @item sample_rate, s
1483 Specify the sample rate, default to 44100.
1486 Each expression in @var{exprs} can contain the following constants:
1490 number of the evaluated sample, starting from 0
1493 time of the evaluated sample expressed in seconds, starting from 0
1500 @subsection Examples
1510 Generate a sin signal with frequency of 440 Hz, set sample rate to
1513 aevalsrc="sin(440*2*PI*t)::s=8000"
1517 Generate a two channels signal, specify the channel layout (Front
1518 Center + Back Center) explicitly:
1520 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1524 Generate white noise:
1526 aevalsrc="-2+random(0)"
1530 Generate an amplitude modulated signal:
1532 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1536 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1538 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1545 Null audio source, return unprocessed audio frames. It is mainly useful
1546 as a template and to be employed in analysis / debugging tools, or as
1547 the source for filters which ignore the input data (for example the sox
1550 It accepts an optional sequence of @var{key}=@var{value} pairs,
1553 The description of the accepted options follows.
1557 @item sample_rate, s
1558 Specify the sample rate, and defaults to 44100.
1560 @item channel_layout, cl
1562 Specify the channel layout, and can be either an integer or a string
1563 representing a channel layout. The default value of @var{channel_layout}
1566 Check the channel_layout_map definition in
1567 @file{libavutil/channel_layout.c} for the mapping between strings and
1568 channel layout values.
1571 Set the number of samples per requested frames.
1575 @subsection Examples
1579 Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1581 anullsrc=r=48000:cl=4
1585 Do the same operation with a more obvious syntax:
1587 anullsrc=r=48000:cl=mono
1592 Buffer audio frames, and make them available to the filter chain.
1594 This source is not intended to be part of user-supplied graph descriptions but
1595 for insertion by calling programs through the interface defined in
1596 @file{libavfilter/buffersrc.h}.
1598 It accepts the following named parameters:
1602 Timebase which will be used for timestamps of submitted frames. It must be
1603 either a floating-point number or in @var{numerator}/@var{denominator} form.
1609 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1611 @item channel_layout
1612 Channel layout of the audio data, in the form that can be accepted by
1613 @code{av_get_channel_layout()}.
1616 All the parameters need to be explicitly defined.
1620 Synthesize a voice utterance using the libflite library.
1622 To enable compilation of this filter you need to configure FFmpeg with
1623 @code{--enable-libflite}.
1625 Note that the flite library is not thread-safe.
1627 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1630 The description of the accepted parameters follows.
1635 If set to 1, list the names of the available voices and exit
1636 immediately. Default value is 0.
1639 Set the maximum number of samples per frame. Default value is 512.
1642 Set the filename containing the text to speak.
1645 Set the text to speak.
1648 Set the voice to use for the speech synthesis. Default value is
1649 @code{kal}. See also the @var{list_voices} option.
1652 @subsection Examples
1656 Read from file @file{speech.txt}, and synthetize the text using the
1657 standard flite voice:
1659 flite=textfile=speech.txt
1663 Read the specified text selecting the @code{slt} voice:
1665 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1669 Input text to ffmpeg:
1671 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1675 Make @file{ffplay} speak the specified text, using @code{flite} and
1676 the @code{lavfi} device:
1678 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1682 For more information about libflite, check:
1683 @url{http://www.speech.cs.cmu.edu/flite/}
1687 Generate an audio signal made of a sine wave with amplitude 1/8.
1689 The audio signal is bit-exact.
1691 The filter accepts the following options:
1696 Set the carrier frequency. Default is 440 Hz.
1698 @item beep_factor, b
1699 Enable a periodic beep every second with frequency @var{beep_factor} times
1700 the carrier frequency. Default is 0, meaning the beep is disabled.
1702 @item sample_rate, s
1703 Specify the sample rate, default is 44100.
1706 Specify the duration of the generated audio stream.
1708 @item samples_per_frame
1709 Set the number of samples per output frame, default is 1024.
1712 @subsection Examples
1717 Generate a simple 440 Hz sine wave:
1723 Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
1727 sine=frequency=220:beep_factor=4:duration=5
1732 @c man end AUDIO SOURCES
1734 @chapter Audio Sinks
1735 @c man begin AUDIO SINKS
1737 Below is a description of the currently available audio sinks.
1739 @section abuffersink
1741 Buffer audio frames, and make them available to the end of filter chain.
1743 This sink is mainly intended for programmatic use, in particular
1744 through the interface defined in @file{libavfilter/buffersink.h}.
1746 It requires a pointer to an AVABufferSinkContext structure, which
1747 defines the incoming buffers' formats, to be passed as the opaque
1748 parameter to @code{avfilter_init_filter} for initialization.
1752 Null audio sink, do absolutely nothing with the input audio. It is
1753 mainly useful as a template and to be employed in analysis / debugging
1756 @section abuffersink
1757 This sink is intended for programmatic use. Frames that arrive on this sink can
1758 be retrieved by the calling program using the interface defined in
1759 @file{libavfilter/buffersink.h}.
1761 This filter accepts no parameters.
1763 @c man end AUDIO SINKS
1765 @chapter Video Filters
1766 @c man begin VIDEO FILTERS
1768 When you configure your FFmpeg build, you can disable any of the
1769 existing filters using @code{--disable-filters}.
1770 The configure output will show the video filters included in your
1773 Below is a description of the currently available video filters.
1775 @section alphaextract
1777 Extract the alpha component from the input as a grayscale video. This
1778 is especially useful with the @var{alphamerge} filter.
1782 Add or replace the alpha component of the primary input with the
1783 grayscale value of a second input. This is intended for use with
1784 @var{alphaextract} to allow the transmission or storage of frame
1785 sequences that have alpha in a format that doesn't support an alpha
1788 For example, to reconstruct full frames from a normal YUV-encoded video
1789 and a separate video created with @var{alphaextract}, you might use:
1791 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1794 Since this filter is designed for reconstruction, it operates on frame
1795 sequences without considering timestamps, and terminates when either
1796 input reaches end of stream. This will cause problems if your encoding
1797 pipeline drops frames. If you're trying to apply an image as an
1798 overlay to a video stream, consider the @var{overlay} filter instead.
1802 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1803 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1804 Substation Alpha) subtitles files.
1808 Compute the bounding box for the non-black pixels in the input frame
1811 This filter computes the bounding box containing all the pixels with a
1812 luminance value greater than the minimum allowed value.
1813 The parameters describing the bounding box are printed on the filter
1816 @section blackdetect
1818 Detect video intervals that are (almost) completely black. Can be
1819 useful to detect chapter transitions, commercials, or invalid
1820 recordings. Output lines contains the time for the start, end and
1821 duration of the detected black interval expressed in seconds.
1823 In order to display the output lines, you need to set the loglevel at
1824 least to the AV_LOG_INFO value.
1826 This filter accepts a list of options in the form of
1827 @var{key}=@var{value} pairs separated by ":". A description of the
1828 accepted options follows.
1831 @item black_min_duration, d
1832 Set the minimum detected black duration expressed in seconds. It must
1833 be a non-negative floating point number.
1835 Default value is 2.0.
1837 @item picture_black_ratio_th, pic_th
1838 Set the threshold for considering a picture "black".
1839 Express the minimum value for the ratio:
1841 @var{nb_black_pixels} / @var{nb_pixels}
1844 for which a picture is considered black.
1845 Default value is 0.98.
1847 @item pixel_black_th, pix_th
1848 Set the threshold for considering a pixel "black".
1850 The threshold expresses the maximum pixel luminance value for which a
1851 pixel is considered "black". The provided value is scaled according to
1852 the following equation:
1854 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1857 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1858 the input video format, the range is [0-255] for YUV full-range
1859 formats and [16-235] for YUV non full-range formats.
1861 Default value is 0.10.
1864 The following example sets the maximum pixel threshold to the minimum
1865 value, and detects only black intervals of 2 or more seconds:
1867 blackdetect=d=2:pix_th=0.00
1872 Detect frames that are (almost) completely black. Can be useful to
1873 detect chapter transitions or commercials. Output lines consist of
1874 the frame number of the detected frame, the percentage of blackness,
1875 the position in the file if known or -1 and the timestamp in seconds.
1877 In order to display the output lines, you need to set the loglevel at
1878 least to the AV_LOG_INFO value.
1880 The filter accepts parameters as a list of @var{key}=@var{value}
1881 pairs, separated by ":". If the key of the first options is omitted,
1882 the arguments are interpreted according to the syntax
1883 blackframe[=@var{amount}[:@var{threshold}]].
1885 The filter accepts the following options:
1890 The percentage of the pixels that have to be below the threshold, defaults to
1894 Threshold below which a pixel value is considered black, defaults to 32.
1900 Blend two video frames into each other.
1902 It takes two input streams and outputs one stream, the first input is the
1903 "top" layer and second input is "bottom" layer.
1904 Output terminates when shortest input terminates.
1906 A description of the accepted options follows.
1914 Set blend mode for specific pixel component or all pixel components in case
1915 of @var{all_mode}. Default value is @code{normal}.
1917 Available values for component modes are:
1950 Set blend opacity for specific pixel component or all pixel components in case
1951 of @var{all_opacity}. Only used in combination with pixel component blend modes.
1958 Set blend expression for specific pixel component or all pixel components in case
1959 of @var{all_expr}. Note that related mode options will be ignored if those are set.
1961 The expressions can use the following variables:
1965 The sequential number of the filtered frame, starting from @code{0}.
1969 the coordinates of the current sample
1973 the width and height of currently filtered plane
1977 Width and height scale depending on the currently filtered plane. It is the
1978 ratio between the corresponding luma plane number of pixels and the current
1979 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
1980 @code{0.5,0.5} for chroma planes.
1983 Time of the current frame, expressed in seconds.
1986 Value of pixel component at current location for first video frame (top layer).
1989 Value of pixel component at current location for second video frame (bottom layer).
1993 @subsection Examples
1997 Apply transition from bottom layer to top layer in first 10 seconds:
1999 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
2003 Apply 1x1 checkerboard effect:
2005 blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
2011 Apply boxblur algorithm to the input video.
2013 The filter accepts parameters as a list of @var{key}=@var{value}
2014 pairs, separated by ":". If the key of the first options is omitted,
2015 the arguments are interpreted according to the syntax
2016 @option{luma_radius}:@option{luma_power}:@option{chroma_radius}:@option{chroma_power}:@option{alpha_radius}:@option{alpha_power}.
2018 This filter accepts the following options:
2031 A description of the accepted options follows.
2034 @item luma_radius, lr
2035 @item chroma_radius, cr
2036 @item alpha_radius, ar
2037 Set an expression for the box radius in pixels used for blurring the
2038 corresponding input plane.
2040 The radius value must be a non-negative number, and must not be
2041 greater than the value of the expression @code{min(w,h)/2} for the
2042 luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma
2045 Default value for @option{luma_radius} is "2". If not specified,
2046 @option{chroma_radius} and @option{alpha_radius} default to the
2047 corresponding value set for @option{luma_radius}.
2049 The expressions can contain the following constants:
2052 the input width and height in pixels
2055 the input chroma image width and height in pixels
2058 horizontal and vertical chroma subsample values. For example for the
2059 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2062 @item luma_power, lp
2063 @item chroma_power, cp
2064 @item alpha_power, ap
2065 Specify how many times the boxblur filter is applied to the
2066 corresponding plane.
2068 Default value for @option{luma_power} is 2. If not specified,
2069 @option{chroma_power} and @option{alpha_power} default to the
2070 corresponding value set for @option{luma_power}.
2072 A value of 0 will disable the effect.
2075 @subsection Examples
2079 Apply a boxblur filter with luma, chroma, and alpha radius
2082 boxblur=luma_radius=2:luma_power=1
2087 Set luma radius to 2, alpha and chroma radius to 0:
2089 boxblur=2:1:cr=0:ar=0
2093 Set luma and chroma radius to a fraction of the video dimension:
2095 boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
2099 @section colormatrix
2101 Convert color matrix.
2103 The filter accepts the following options:
2108 Specify the source and destination color matrix. Both values must be
2111 The accepted values are:
2127 For example to convert from BT.601 to SMPTE-240M, use the command:
2129 colormatrix=bt601:smpte240m
2134 Copy the input source unchanged to the output. Mainly useful for
2139 Crop the input video to given dimensions.
2141 This filter accepts a list of @var{key}=@var{value} pairs as argument,
2142 separated by ':'. If the key of the first options is omitted, the
2143 arguments are interpreted according to the syntax
2144 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
2146 A description of the accepted options follows:
2149 Width of the output video. It defaults to @code{iw}.
2150 This expression is evaluated only once during the filter
2154 Height of the output video. It defaults to @code{ih}.
2155 This expression is evaluated only once during the filter
2159 Horizontal position, in the input video, of the left edge of the output video.
2160 It defaults to @code{(in_w-out_w)/2}.
2161 This expression is evaluated per-frame.
2164 Vertical position, in the input video, of the top edge of the output video.
2165 It defaults to @code{(in_h-out_h)/2}.
2166 This expression is evaluated per-frame.
2169 If set to 1 will force the output display aspect ratio
2170 to be the same of the input, by changing the output sample aspect
2171 ratio. It defaults to 0.
2174 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
2175 expressions containing the following constants:
2179 the computed values for @var{x} and @var{y}. They are evaluated for
2183 the input width and height
2186 same as @var{in_w} and @var{in_h}
2189 the output (cropped) width and height
2192 same as @var{out_w} and @var{out_h}
2195 same as @var{iw} / @var{ih}
2198 input sample aspect ratio
2201 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2204 horizontal and vertical chroma subsample values. For example for the
2205 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2208 the number of input frame, starting from 0
2211 timestamp expressed in seconds, NAN if the input timestamp is unknown
2215 The expression for @var{out_w} may depend on the value of @var{out_h},
2216 and the expression for @var{out_h} may depend on @var{out_w}, but they
2217 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
2218 evaluated after @var{out_w} and @var{out_h}.
2220 The @var{x} and @var{y} parameters specify the expressions for the
2221 position of the top-left corner of the output (non-cropped) area. They
2222 are evaluated for each frame. If the evaluated value is not valid, it
2223 is approximated to the nearest valid value.
2225 The expression for @var{x} may depend on @var{y}, and the expression
2226 for @var{y} may depend on @var{x}.
2228 @subsection Examples
2232 Crop area with size 100x100 at position (12,34).
2237 Using named options, the example above becomes:
2239 crop=w=100:h=100:x=12:y=34
2243 Crop the central input area with size 100x100:
2249 Crop the central input area with size 2/3 of the input video:
2251 crop=2/3*in_w:2/3*in_h
2255 Crop the input video central square:
2262 Delimit the rectangle with the top-left corner placed at position
2263 100:100 and the right-bottom corner corresponding to the right-bottom
2264 corner of the input image:
2266 crop=in_w-100:in_h-100:100:100
2270 Crop 10 pixels from the left and right borders, and 20 pixels from
2271 the top and bottom borders
2273 crop=in_w-2*10:in_h-2*20
2277 Keep only the bottom right quarter of the input image:
2279 crop=in_w/2:in_h/2:in_w/2:in_h/2
2283 Crop height for getting Greek harmony:
2285 crop=in_w:1/PHI*in_w
2289 Appply trembling effect:
2291 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)
2295 Apply erratic camera effect depending on timestamp:
2297 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)"
2301 Set x depending on the value of y:
2303 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
2309 Auto-detect crop size.
2311 Calculate necessary cropping parameters and prints the recommended
2312 parameters through the logging system. The detected dimensions
2313 correspond to the non-black area of the input video.
2315 The filter accepts parameters as a list of @var{key}=@var{value}
2316 pairs, separated by ":". If the key of the first options is omitted,
2317 the arguments are interpreted according to the syntax
2318 [@option{limit}[:@option{round}[:@option{reset}]]].
2320 A description of the accepted options follows.
2325 Set higher black value threshold, which can be optionally specified
2326 from nothing (0) to everything (255). An intensity value greater
2327 to the set value is considered non-black. Default value is 24.
2330 Set the value for which the width/height should be divisible by. The
2331 offset is automatically adjusted to center the video. Use 2 to get
2332 only even dimensions (needed for 4:2:2 video). 16 is best when
2333 encoding to most video codecs. Default value is 16.
2336 Set the counter that determines after how many frames cropdetect will
2337 reset the previously detected largest video area and start over to
2338 detect the current optimal crop area. Default value is 0.
2340 This can be useful when channel logos distort the video area. 0
2341 indicates never reset and return the largest area encountered during
2347 Apply color adjustments using curves.
2349 This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
2350 component (red, green and blue) has its values defined by @var{N} key points
2351 tied from each other using a smooth curve. The x-axis represents the pixel
2352 values from the input frame, and the y-axis the new pixel values to be set for
2355 By default, a component curve is defined by the two points @var{(0;0)} and
2356 @var{(1;1)}. This creates a straight line where each original pixel value is
2357 "adjusted" to its own value, which means no change to the image.
2359 The filter allows you to redefine these two points and add some more. A new
2360 curve (using a natural cubic spline interpolation) will be define to pass
2361 smoothly through all these new coordinates. The new defined points needs to be
2362 strictly increasing over the x-axis, and their @var{x} and @var{y} values must
2363 be in the @var{[0;1]} interval. If the computed curves happened to go outside
2364 the vector spaces, the values will be clipped accordingly.
2366 If there is no key point defined in @code{x=0}, the filter will automatically
2367 insert a @var{(0;0)} point. In the same way, if there is no key point defined
2368 in @code{x=1}, the filter will automatically insert a @var{(1;1)} point.
2370 The filter accepts the following options:
2374 Select one of the available color presets. This option can not be used in
2375 addition to the @option{r}, @option{g}, @option{b} parameters.
2376 Available presets are:
2379 @item color_negative
2382 @item increase_contrast
2384 @item linear_contrast
2385 @item medium_contrast
2387 @item strong_contrast
2390 Default is @code{none}.
2392 Set the key points for the red component.
2394 Set the key points for the green component.
2396 Set the key points for the blue component.
2398 Set the key points for all components.
2399 Can be used in addition to the other key points component
2400 options. In this case, the unset component(s) will fallback on this
2401 @option{all} setting.
2404 To avoid some filtergraph syntax conflicts, each key points list need to be
2405 defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}.
2407 @subsection Examples
2411 Increase slightly the middle level of blue:
2413 curves=blue='0.5/0.58'
2419 curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8'
2421 Here we obtain the following coordinates for each components:
2424 @code{(0;0.11) (0.42;0.51) (1;0.95)}
2426 @code{(0;0) (0.50;0.48) (1;1)}
2428 @code{(0;0.22) (0.49;0.44) (1;0.80)}
2432 The previous example can also be achieved with the associated built-in preset:
2434 curves=preset=vintage
2446 Drop frames that do not differ greatly from the previous frame in
2447 order to reduce frame rate.
2449 The main use of this filter is for very-low-bitrate encoding
2450 (e.g. streaming over dialup modem), but it could in theory be used for
2451 fixing movies that were inverse-telecined incorrectly.
2453 A description of the accepted options follows.
2457 Set the maximum number of consecutive frames which can be dropped (if
2458 positive), or the minimum interval between dropped frames (if
2459 negative). If the value is 0, the frame is dropped unregarding the
2460 number of previous sequentially dropped frames.
2467 Set the dropping threshold values.
2469 Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and
2470 represent actual pixel value differences, so a threshold of 64
2471 corresponds to 1 unit of difference for each pixel, or the same spread
2472 out differently over the block.
2474 A frame is a candidate for dropping if no 8x8 blocks differ by more
2475 than a threshold of @option{hi}, and if no more than @option{frac} blocks (1
2476 meaning the whole image) differ by more than a threshold of @option{lo}.
2478 Default value for @option{hi} is 64*12, default value for @option{lo} is
2479 64*5, and default value for @option{frac} is 0.33.
2484 Suppress a TV station logo by a simple interpolation of the surrounding
2485 pixels. Just set a rectangle covering the logo and watch it disappear
2486 (and sometimes something even uglier appear - your mileage may vary).
2488 This filter accepts the following options:
2492 Specify the top left corner coordinates of the logo. They must be
2496 Specify the width and height of the logo to clear. They must be
2500 Specify the thickness of the fuzzy edge of the rectangle (added to
2501 @var{w} and @var{h}). The default value is 4.
2504 When set to 1, a green rectangle is drawn on the screen to simplify
2505 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
2506 @var{band} is set to 4. The default value is 0.
2510 @subsection Examples
2514 Set a rectangle covering the area with top left corner coordinates 0,0
2515 and size 100x77, setting a band of size 10:
2517 delogo=x=0:y=0:w=100:h=77:band=10
2524 Attempt to fix small changes in horizontal and/or vertical shift. This
2525 filter helps remove camera shake from hand-holding a camera, bumping a
2526 tripod, moving on a vehicle, etc.
2528 The filter accepts the following options:
2536 Specify a rectangular area where to limit the search for motion
2538 If desired the search for motion vectors can be limited to a
2539 rectangular area of the frame defined by its top left corner, width
2540 and height. These parameters have the same meaning as the drawbox
2541 filter which can be used to visualise the position of the bounding
2544 This is useful when simultaneous movement of subjects within the frame
2545 might be confused for camera motion by the motion vector search.
2547 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
2548 then the full frame is used. This allows later options to be set
2549 without specifying the bounding box for the motion vector search.
2551 Default - search the whole frame.
2555 Specify the maximum extent of movement in x and y directions in the
2556 range 0-64 pixels. Default 16.
2559 Specify how to generate pixels to fill blanks at the edge of the
2560 frame. Available values are:
2563 Fill zeroes at blank locations
2565 Original image at blank locations
2567 Extruded edge value at blank locations
2569 Mirrored edge at blank locations
2571 Default value is @samp{mirror}.
2574 Specify the blocksize to use for motion search. Range 4-128 pixels,
2578 Specify the contrast threshold for blocks. Only blocks with more than
2579 the specified contrast (difference between darkest and lightest
2580 pixels) will be considered. Range 1-255, default 125.
2583 Specify the search strategy. Available values are:
2586 Set exhaustive search
2588 Set less exhaustive search.
2590 Default value is @samp{exhaustive}.
2593 If set then a detailed log of the motion search is written to the
2597 If set to 1, specify using OpenCL capabilities, only available if
2598 FFmpeg was configured with @code{--enable-opencl}. Default value is 0.
2604 Draw a colored box on the input image.
2606 This filter accepts the following options:
2610 Specify the top left corner coordinates of the box. Default to 0.
2614 Specify the width and height of the box, if 0 they are interpreted as
2615 the input width and height. Default to 0.
2618 Specify the color of the box to write, it can be the name of a color
2619 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
2620 value @code{invert} is used, the box edge color is the same as the
2621 video with inverted luma.
2624 Set the thickness of the box edge. Default value is @code{4}.
2627 @subsection Examples
2631 Draw a black box around the edge of the input image:
2637 Draw a box with color red and an opacity of 50%:
2639 drawbox=10:20:200:60:red@@0.5
2642 The previous example can be specified as:
2644 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
2648 Fill the box with pink color:
2650 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
2657 Draw text string or text from specified file on top of video using the
2658 libfreetype library.
2660 To enable compilation of this filter you need to configure FFmpeg with
2661 @code{--enable-libfreetype}.
2665 The description of the accepted parameters follows.
2670 Used to draw a box around text using background color.
2671 Value should be either 1 (enable) or 0 (disable).
2672 The default value of @var{box} is 0.
2675 The color to be used for drawing box around text.
2676 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2677 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2678 The default value of @var{boxcolor} is "white".
2681 Set an expression which specifies if the text should be drawn. If the
2682 expression evaluates to 0, the text is not drawn. This is useful for
2683 specifying that the text should be drawn only when specific conditions
2686 Default value is "1".
2688 See below for the list of accepted constants and functions.
2691 Select how the @var{text} is expanded. Can be either @code{none},
2692 @code{strftime} (deprecated) or
2693 @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section
2697 If true, check and fix text coords to avoid clipping.
2700 The color to be used for drawing fonts.
2701 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2702 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2703 The default value of @var{fontcolor} is "black".
2706 The font file to be used for drawing text. Path must be included.
2707 This parameter is mandatory.
2710 The font size to be used for drawing text.
2711 The default value of @var{fontsize} is 16.
2714 Flags to be used for loading the fonts.
2716 The flags map the corresponding flags supported by libfreetype, and are
2717 a combination of the following values:
2724 @item vertical_layout
2725 @item force_autohint
2728 @item ignore_global_advance_width
2730 @item ignore_transform
2737 Default value is "render".
2739 For more information consult the documentation for the FT_LOAD_*
2743 The color to be used for drawing a shadow behind the drawn text. It
2744 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2745 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2746 The default value of @var{shadowcolor} is "black".
2748 @item shadowx, shadowy
2749 The x and y offsets for the text shadow position with respect to the
2750 position of the text. They can be either positive or negative
2751 values. Default value for both is "0".
2754 The size in number of spaces to use for rendering the tab.
2758 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2759 format. It can be used with or without text parameter. @var{timecode_rate}
2760 option must be specified.
2762 @item timecode_rate, rate, r
2763 Set the timecode frame rate (timecode only).
2766 The text string to be drawn. The text must be a sequence of UTF-8
2768 This parameter is mandatory if no file is specified with the parameter
2772 A text file containing text to be drawn. The text must be a sequence
2773 of UTF-8 encoded characters.
2775 This parameter is mandatory if no text string is specified with the
2776 parameter @var{text}.
2778 If both @var{text} and @var{textfile} are specified, an error is thrown.
2781 If set to 1, the @var{textfile} will be reloaded before each frame.
2782 Be sure to update it atomically, or it may be read partially, or even fail.
2785 The expressions which specify the offsets where text will be drawn
2786 within the video frame. They are relative to the top/left border of the
2789 The default value of @var{x} and @var{y} is "0".
2791 See below for the list of accepted constants and functions.
2794 The parameters for @var{x} and @var{y} are expressions containing the
2795 following constants and functions:
2799 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2802 horizontal and vertical chroma subsample values. For example for the
2803 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2806 the height of each text line
2814 @item max_glyph_a, ascent
2815 the maximum distance from the baseline to the highest/upper grid
2816 coordinate used to place a glyph outline point, for all the rendered
2818 It is a positive value, due to the grid's orientation with the Y axis
2821 @item max_glyph_d, descent
2822 the maximum distance from the baseline to the lowest grid coordinate
2823 used to place a glyph outline point, for all the rendered glyphs.
2824 This is a negative value, due to the grid's orientation, with the Y axis
2828 maximum glyph height, that is the maximum height for all the glyphs
2829 contained in the rendered text, it is equivalent to @var{ascent} -
2833 maximum glyph width, that is the maximum width for all the glyphs
2834 contained in the rendered text
2837 the number of input frame, starting from 0
2839 @item rand(min, max)
2840 return a random number included between @var{min} and @var{max}
2843 input sample aspect ratio
2846 timestamp expressed in seconds, NAN if the input timestamp is unknown
2849 the height of the rendered text
2852 the width of the rendered text
2855 the x and y offset coordinates where the text is drawn.
2857 These parameters allow the @var{x} and @var{y} expressions to refer
2858 each other, so you can for example specify @code{y=x/dar}.
2861 If libavfilter was built with @code{--enable-fontconfig}, then
2862 @option{fontfile} can be a fontconfig pattern or omitted.
2864 @anchor{drawtext_expansion}
2865 @subsection Text expansion
2867 If @option{expansion} is set to @code{strftime},
2868 the filter recognizes strftime() sequences in the provided text and
2869 expands them accordingly. Check the documentation of strftime(). This
2870 feature is deprecated.
2872 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2874 If @option{expansion} is set to @code{normal} (which is the default),
2875 the following expansion mechanism is used.
2877 The backslash character '\', followed by any character, always expands to
2878 the second character.
2880 Sequence of the form @code{%@{...@}} are expanded. The text between the
2881 braces is a function name, possibly followed by arguments separated by ':'.
2882 If the arguments contain special characters or delimiters (':' or '@}'),
2883 they should be escaped.
2885 Note that they probably must also be escaped as the value for the
2886 @option{text} option in the filter argument string and as the filter
2887 argument in the filtergraph description, and possibly also for the shell,
2888 that makes up to four levels of escaping; using a text file avoids these
2891 The following functions are available:
2896 The expression evaluation result.
2898 It must take one argument specifying the expression to be evaluated,
2899 which accepts the same constants and functions as the @var{x} and
2900 @var{y} values. Note that not all constants should be used, for
2901 example the text size is not known when evaluating the expression, so
2902 the constants @var{text_w} and @var{text_h} will have an undefined
2906 The time at which the filter is running, expressed in UTC.
2907 It can accept an argument: a strftime() format string.
2910 The time at which the filter is running, expressed in the local time zone.
2911 It can accept an argument: a strftime() format string.
2914 The frame number, starting from 0.
2917 The timestamp of the current frame, in seconds, with microsecond accuracy.
2921 @subsection Examples
2925 Draw "Test Text" with font FreeSerif, using the default values for the
2926 optional parameters.
2929 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2933 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2934 and y=50 (counting from the top-left corner of the screen), text is
2935 yellow with a red box around it. Both the text and the box have an
2939 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2940 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2943 Note that the double quotes are not necessary if spaces are not used
2944 within the parameter list.
2947 Show the text at the center of the video frame:
2949 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2953 Show a text line sliding from right to left in the last row of the video
2954 frame. The file @file{LONG_LINE} is assumed to contain a single line
2957 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2961 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2963 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2967 Draw a single green letter "g", at the center of the input video.
2968 The glyph baseline is placed at half screen height.
2970 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2974 Show text for 1 second every 3 seconds:
2976 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2980 Use fontconfig to set the font. Note that the colons need to be escaped.
2982 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2986 Print the date of a real-time encoding (see strftime(3)):
2988 drawtext='fontfile=FreeSans.ttf:text=%@{localtime:%a %b %d %Y@}'
2993 For more information about libfreetype, check:
2994 @url{http://www.freetype.org/}.
2996 For more information about fontconfig, check:
2997 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
3001 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
3003 The filter accepts the following options:
3007 Set low and high threshold values used by the Canny thresholding
3010 The high threshold selects the "strong" edge pixels, which are then
3011 connected through 8-connectivity with the "weak" edge pixels selected
3012 by the low threshold.
3014 @var{low} and @var{high} threshold values must be choosen in the range
3015 [0,1], and @var{low} should be lesser or equal to @var{high}.
3017 Default value for @var{low} is @code{20/255}, and default value for @var{high}
3023 edgedetect=low=0.1:high=0.4
3028 Apply fade-in/out effect to input video.
3030 This filter accepts the following options:
3034 The effect type -- can be either "in" for fade-in, or "out" for a fade-out
3036 Default is @code{in}.
3038 @item start_frame, s
3039 Specify the number of the start frame for starting to apply the fade
3040 effect. Default is 0.
3043 The number of frames for which the fade effect has to last. At the end of the
3044 fade-in effect the output video will have the same intensity as the input video,
3045 at the end of the fade-out transition the output video will be completely black.
3049 If set to 1, fade only alpha channel, if one exists on the input.
3053 @subsection Examples
3057 Fade in first 30 frames of video:
3062 The command above is equivalent to:
3068 Fade out last 45 frames of a 200-frame video:
3071 fade=type=out:start_frame=155:nb_frames=45
3075 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
3077 fade=in:0:25, fade=out:975:25
3081 Make first 5 frames black, then fade in from frame 5-24:
3087 Fade in alpha over first 25 frames of video:
3089 fade=in:0:25:alpha=1
3095 Extract a single field from an interlaced image using stride
3096 arithmetic to avoid wasting CPU time. The output frames are marked as
3099 The filter accepts the following options:
3103 Specify whether to extract the top (if the value is @code{0} or
3104 @code{top}) or the bottom field (if the value is @code{1} or
3110 Transform the field order of the input video.
3112 This filter accepts the following options:
3117 Output field order. Valid values are @var{tff} for top field first or @var{bff}
3118 for bottom field first.
3121 Default value is @samp{tff}.
3123 Transformation is achieved by shifting the picture content up or down
3124 by one line, and filling the remaining line with appropriate picture content.
3125 This method is consistent with most broadcast field order converters.
3127 If the input video is not flagged as being interlaced, or it is already
3128 flagged as being of the required output field order then this filter does
3129 not alter the incoming video.
3131 This filter is very useful when converting to or from PAL DV material,
3132 which is bottom field first.
3136 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
3141 Buffer input images and send them when they are requested.
3143 This filter is mainly useful when auto-inserted by the libavfilter
3146 The filter does not take parameters.
3151 Convert the input video to one of the specified pixel formats.
3152 Libavfilter will try to pick one that is supported for the input to
3155 This filter accepts the following parameters:
3159 A '|'-separated list of pixel format names, for example
3160 "pix_fmts=yuv420p|monow|rgb24".
3164 @subsection Examples
3168 Convert the input video to the format @var{yuv420p}
3170 format=pix_fmts=yuv420p
3173 Convert the input video to any of the formats in the list
3175 format=pix_fmts=yuv420p|yuv444p|yuv410p
3181 Convert the video to specified constant frame rate by duplicating or dropping
3182 frames as necessary.
3184 This filter accepts the following named parameters:
3188 Desired output frame rate. The default is @code{25}.
3193 Possible values are:
3196 zero round towards 0
3200 round towards -infinity
3202 round towards +infinity
3206 The default is @code{near}.
3210 Alternatively, the options can be specified as a flat string:
3211 @var{fps}[:@var{round}].
3213 See also the @ref{setpts} filter.
3217 Select one frame every N-th frame.
3219 This filter accepts the following option:
3222 Select frame after every @code{step} frames.
3223 Allowed values are positive integers higher than 0. Default value is @code{1}.
3229 Apply a frei0r effect to the input video.
3231 To enable compilation of this filter you need to install the frei0r
3232 header and configure FFmpeg with @code{--enable-frei0r}.
3234 This filter accepts the following options:
3239 The name to the frei0r effect to load. If the environment variable
3240 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
3241 directories specified by the colon separated list in @env{FREIOR_PATH},
3242 otherwise in the standard frei0r paths, which are in this order:
3243 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3244 @file{/usr/lib/frei0r-1/}.
3247 A '|'-separated list of parameters to pass to the frei0r effect.
3251 A frei0r effect parameter can be a boolean (whose values are specified
3252 with "y" and "n"), a double, a color (specified by the syntax
3253 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3254 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3255 description), a position (specified by the syntax @var{X}/@var{Y},
3256 @var{X} and @var{Y} being float numbers) and a string.
3258 The number and kind of parameters depend on the loaded effect. If an
3259 effect parameter is not specified the default value is set.
3261 @subsection Examples
3265 Apply the distort0r effect, set the first two double parameters:
3267 frei0r=filter_name=distort0r:filter_params=0.5|0.01
3271 Apply the colordistance effect, take a color as first parameter:
3273 frei0r=colordistance:0.2/0.3/0.4
3274 frei0r=colordistance:violet
3275 frei0r=colordistance:0x112233
3279 Apply the perspective effect, specify the top left and top right image
3282 frei0r=perspective:0.2/0.2|0.8/0.2
3286 For more information see:
3287 @url{http://frei0r.dyne.org}
3291 The filter accepts the following options:
3295 the luminance expression
3297 the chrominance blue expression
3299 the chrominance red expression
3301 the alpha expression
3304 If one of the chrominance expression is not defined, it falls back on the other
3305 one. If no alpha expression is specified it will evaluate to opaque value.
3306 If none of chrominance expressions are
3307 specified, they will evaluate the luminance expression.
3309 The expressions can use the following variables and functions:
3313 The sequential number of the filtered frame, starting from @code{0}.
3317 The coordinates of the current sample.
3321 The width and height of the image.
3325 Width and height scale depending on the currently filtered plane. It is the
3326 ratio between the corresponding luma plane number of pixels and the current
3327 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3328 @code{0.5,0.5} for chroma planes.
3331 Time of the current frame, expressed in seconds.
3334 Return the value of the pixel at location (@var{x},@var{y}) of the current
3338 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3342 Return the value of the pixel at location (@var{x},@var{y}) of the
3343 blue-difference chroma plane. Returns 0 if there is no such plane.
3346 Return the value of the pixel at location (@var{x},@var{y}) of the
3347 red-difference chroma plane. Returns 0 if there is no such plane.
3350 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
3351 plane. Returns 0 if there is no such plane.
3354 For functions, if @var{x} and @var{y} are outside the area, the value will be
3355 automatically clipped to the closer edge.
3357 @subsection Examples
3361 Flip the image horizontally:
3367 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3368 wavelength of 100 pixels:
3370 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3374 Generate a fancy enigmatic moving light:
3376 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
3382 Fix the banding artifacts that are sometimes introduced into nearly flat
3383 regions by truncation to 8bit color depth.
3384 Interpolate the gradients that should go where the bands are, and
3387 This filter is designed for playback only. Do not use it prior to
3388 lossy compression, because compression tends to lose the dither and
3389 bring back the bands.
3391 This filter accepts the following options:
3396 The maximum amount by which the filter will change any one pixel. Also the
3397 threshold for detecting nearly flat regions. Acceptable values range from .51 to
3398 64, default value is 1.2, out-of-range values will be clipped to the valid
3402 The neighborhood to fit the gradient to. A larger radius makes for smoother
3403 gradients, but also prevents the filter from modifying the pixels near detailed
3404 regions. Acceptable values are 8-32, default value is 16, out-of-range values
3405 will be clipped to the valid range.
3409 Alternatively, the options can be specified as a flat string:
3410 @var{strength}[:@var{radius}]
3412 @subsection Examples
3416 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3422 Specify radius, omitting the strength (which will fall-back to the default
3432 Flip the input video horizontally.
3434 For example to horizontally flip the input video with @command{ffmpeg}:
3436 ffmpeg -i in.avi -vf "hflip" out.avi
3440 This filter applies a global color histogram equalization on a
3443 It can be used to correct video that has a compressed range of pixel
3444 intensities. The filter redistributes the pixel intensities to
3445 equalize their distribution across the intensity range. It may be
3446 viewed as an "automatically adjusting contrast filter". This filter is
3447 useful only for correcting degraded or poorly captured source
3450 The filter accepts the following options:
3454 Determine the amount of equalization to be applied. As the strength
3455 is reduced, the distribution of pixel intensities more-and-more
3456 approaches that of the input frame. The value must be a float number
3457 in the range [0,1] and defaults to 0.200.
3460 Set the maximum intensity that can generated and scale the output
3461 values appropriately. The strength should be set as desired and then
3462 the intensity can be limited if needed to avoid washing-out. The value
3463 must be a float number in the range [0,1] and defaults to 0.210.
3466 Set the antibanding level. If enabled the filter will randomly vary
3467 the luminance of output pixels by a small amount to avoid banding of
3468 the histogram. Possible values are @code{none}, @code{weak} or
3469 @code{strong}. It defaults to @code{none}.
3474 Compute and draw a color distribution histogram for the input video.
3476 The computed histogram is a representation of distribution of color components
3479 The filter accepts the following options:
3485 It accepts the following values:
3488 standard histogram that display color components distribution in an image.
3489 Displays color graph for each color component. Shows distribution
3490 of the Y, U, V, A or G, B, R components, depending on input format,
3491 in current frame. Bellow each graph is color component scale meter.
3494 chroma values in vectorscope, if brighter more such chroma values are
3495 distributed in an image.
3496 Displays chroma values (U/V color placement) in two dimensional graph
3497 (which is called a vectorscope). It can be used to read of the hue and
3498 saturation of the current frame. At a same time it is a histogram.
3499 The whiter a pixel in the vectorscope, the more pixels of the input frame
3500 correspond to that pixel (that is the more pixels have this chroma value).
3501 The V component is displayed on the horizontal (X) axis, with the leftmost
3502 side being V = 0 and the rightmost side being V = 255.
3503 The U component is displayed on the vertical (Y) axis, with the top
3504 representing U = 0 and the bottom representing U = 255.
3506 The position of a white pixel in the graph corresponds to the chroma value
3507 of a pixel of the input clip. So the graph can be used to read of the
3508 hue (color flavor) and the saturation (the dominance of the hue in the color).
3509 As the hue of a color changes, it moves around the square. At the center of
3510 the square, the saturation is zero, which means that the corresponding pixel
3511 has no color. If you increase the amount of a specific color, while leaving
3512 the other colors unchanged, the saturation increases, and you move towards
3513 the edge of the square.
3516 chroma values in vectorscope, similar as @code{color} but actual chroma values
3520 per row/column color component graph. In row mode graph in the left side represents
3521 color component value 0 and right side represents value = 255. In column mode top
3522 side represents color component value = 0 and bottom side represents value = 255.
3524 Default value is @code{levels}.
3527 Set height of level in @code{levels}. Default value is @code{200}.
3528 Allowed range is [50, 2048].
3531 Set height of color scale in @code{levels}. Default value is @code{12}.
3532 Allowed range is [0, 40].
3535 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3536 of same luminance values across input rows/columns are distributed.
3537 Default value is @code{10}. Allowed range is [1, 255].
3540 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3541 Default is @code{row}.
3544 Set display mode for @code{waveform} and @code{levels}.
3545 It accepts the following values:
3548 Display separate graph for the color components side by side in
3549 @code{row} waveform mode or one below other in @code{column} waveform mode
3550 for @code{waveform} histogram mode. For @code{levels} histogram mode
3551 per color component graphs are placed one bellow other.
3553 This display mode in @code{waveform} histogram mode makes it easy to spot
3554 color casts in the highlights and shadows of an image, by comparing the
3555 contours of the top and the bottom of each waveform.
3556 Since whites, grays, and blacks are characterized by
3557 exactly equal amounts of red, green, and blue, neutral areas of the
3558 picture should display three waveforms of roughly equal width/height.
3559 If not, the correction is easy to make by making adjustments to level the
3563 Presents information that's identical to that in the @code{parade}, except
3564 that the graphs representing color components are superimposed directly
3567 This display mode in @code{waveform} histogram mode can make it easier to spot
3568 the relative differences or similarities in overlapping areas of the color
3569 components that are supposed to be identical, such as neutral whites, grays,
3572 Default is @code{parade}.
3575 @subsection Examples
3580 Calculate and draw histogram:
3582 ffplay -i input -vf histogram
3589 High precision/quality 3d denoise filter. This filter aims to reduce
3590 image noise producing smooth images and making still images really
3591 still. It should enhance compressibility.
3593 It accepts the following optional parameters:
3597 a non-negative float number which specifies spatial luma strength,
3600 @item chroma_spatial
3601 a non-negative float number which specifies spatial chroma strength,
3602 defaults to 3.0*@var{luma_spatial}/4.0
3605 a float number which specifies luma temporal strength, defaults to
3606 6.0*@var{luma_spatial}/4.0
3609 a float number which specifies chroma temporal strength, defaults to
3610 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3615 Modify the hue and/or the saturation of the input.
3617 This filter accepts the following optional named options:
3621 Specify the hue angle as a number of degrees. It accepts a float
3622 number or an expression, and defaults to 0.0.
3625 Specify the hue angle as a number of radians. It accepts a float
3626 number or an expression, and defaults to 0.0.
3629 Specify the saturation in the [-10,10] range. It accepts a float number and
3633 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3634 following constants:
3638 frame count of the input frame starting from 0
3641 presentation timestamp of the input frame expressed in time base units
3644 frame rate of the input video, NAN if the input frame rate is unknown
3647 timestamp expressed in seconds, NAN if the input timestamp is unknown
3650 time base of the input video
3653 The options can also be set using the syntax: @var{hue}:@var{saturation}
3655 In this case @var{hue} is expressed in degrees.
3657 @subsection Examples
3661 Set the hue to 90 degrees and the saturation to 1.0:
3667 Same command but expressing the hue in radians:
3673 Same command without named options, hue must be expressed in degrees:
3679 Note that "h:s" syntax does not support expressions for the values of
3680 h and s, so the following example will issue an error:
3686 Rotate hue and make the saturation swing between 0
3687 and 2 over a period of 1 second:
3689 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3693 Apply a 3 seconds saturation fade-in effect starting at 0:
3698 The general fade-in expression can be written as:
3700 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3704 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3706 hue="s=max(0\, min(1\, (8-t)/3))"
3709 The general fade-out expression can be written as:
3711 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3716 @subsection Commands
3718 This filter supports the following command:
3721 Modify the hue and/or the saturation of the input video.
3722 The command accepts the same named options and syntax than when calling the
3723 filter from the command-line.
3725 If a parameter is omitted, it is kept at its current value.
3730 Detect video interlacing type.
3732 This filter tries to detect if the input is interlaced or progressive,
3733 top or bottom field first.
3735 The filter accepts the following options:
3739 Set interlacing threshold.
3741 Set progressive threshold.
3746 Deinterleave or interleave fields.
3748 This filter allows to process interlaced images fields without
3749 deinterlacing them. Deinterleaving splits the input frame into 2
3750 fields (so called half pictures). Odd lines are moved to the top
3751 half of the output image, even lines to the bottom half.
3752 You can process (filter) them independently and then re-interleave them.
3754 The filter accepts the following options:
3758 @item chroma_mode, s
3760 Available values for @var{luma_mode}, @var{chroma_mode} and
3761 @var{alpha_mode} are:
3767 @item deinterleave, d
3768 Deinterleave fields, placing one above the other.
3771 Interleave fields. Reverse the effect of deinterleaving.
3773 Default value is @code{none}.
3776 @item chroma_swap, cs
3777 @item alpha_swap, as
3778 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3783 Deinterlace input video by applying Donald Graft's adaptive kernel
3784 deinterling. Work on interlaced parts of a video to produce
3787 The description of the accepted parameters follows.
3791 Set the threshold which affects the filter's tolerance when
3792 determining if a pixel line must be processed. It must be an integer
3793 in the range [0,255] and defaults to 10. A value of 0 will result in
3794 applying the process on every pixels.
3797 Paint pixels exceeding the threshold value to white if set to 1.
3801 Set the fields order. Swap fields if set to 1, leave fields alone if
3805 Enable additional sharpening if set to 1. Default is 0.
3808 Enable twoway sharpening if set to 1. Default is 0.
3811 @subsection Examples
3815 Apply default values:
3817 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3821 Enable additional sharpening:
3827 Paint processed pixels in white:
3833 @section lut, lutrgb, lutyuv
3835 Compute a look-up table for binding each pixel component input value
3836 to an output value, and apply it to input video.
3838 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3839 to an RGB input video.
3841 These filters accept the following options:
3844 set first pixel component expression
3846 set second pixel component expression
3848 set third pixel component expression
3850 set fourth pixel component expression, corresponds to the alpha component
3853 set red component expression
3855 set green component expression
3857 set blue component expression
3859 alpha component expression
3862 set Y/luminance component expression
3864 set U/Cb component expression
3866 set V/Cr component expression
3869 Each of them specifies the expression to use for computing the lookup table for
3870 the corresponding pixel component values.
3872 The exact component associated to each of the @var{c*} options depends on the
3875 The @var{lut} filter requires either YUV or RGB pixel formats in input,
3876 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
3878 The expressions can contain the following constants and functions:
3882 the input width and height
3885 input value for the pixel component
3888 the input value clipped in the @var{minval}-@var{maxval} range
3891 maximum value for the pixel component
3894 minimum value for the pixel component
3897 the negated value for the pixel component value clipped in the
3898 @var{minval}-@var{maxval} range , it corresponds to the expression
3899 "maxval-clipval+minval"
3902 the computed value in @var{val} clipped in the
3903 @var{minval}-@var{maxval} range
3905 @item gammaval(gamma)
3906 the computed gamma correction value of the pixel component value
3907 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3909 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3913 All expressions default to "val".
3915 @subsection Examples
3921 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3922 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3925 The above is the same as:
3927 lutrgb="r=negval:g=negval:b=negval"
3928 lutyuv="y=negval:u=negval:v=negval"
3938 Remove chroma components, turns the video into a graytone image:
3940 lutyuv="u=128:v=128"
3944 Apply a luma burning effect:
3950 Remove green and blue components:
3956 Set a constant alpha channel value on input:
3958 format=rgba,lutrgb=a="maxval-minval/2"
3962 Correct luminance gamma by a 0.5 factor:
3964 lutyuv=y=gammaval(0.5)
3968 Discard least significant bits of luma:
3970 lutyuv=y='bitand(val, 128+64+32)'
3976 Apply an MPlayer filter to the input video.
3978 This filter provides a wrapper around most of the filters of
3981 This wrapper is considered experimental. Some of the wrapped filters
3982 may not work properly and we may drop support for them, as they will
3983 be implemented natively into FFmpeg. Thus you should avoid
3984 depending on them when writing portable scripts.
3986 The filters accepts the parameters:
3987 @var{filter_name}[:=]@var{filter_params}
3989 @var{filter_name} is the name of a supported MPlayer filter,
3990 @var{filter_params} is a string containing the parameters accepted by
3993 The list of the currently supported filters follows:
4020 The parameter syntax and behavior for the listed filters are the same
4021 of the corresponding MPlayer filters. For detailed instructions check
4022 the "VIDEO FILTERS" section in the MPlayer manual.
4024 @subsection Examples
4028 Adjust gamma, brightness, contrast:
4034 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
4040 This filter accepts an integer in input, if non-zero it negates the
4041 alpha component (if available). The default value in input is 0.
4045 Force libavfilter not to use any of the specified pixel formats for the
4046 input to the next filter.
4048 This filter accepts the following parameters:
4052 A '|'-separated list of pixel format names, for example
4053 "pix_fmts=yuv420p|monow|rgb24".
4057 @subsection Examples
4061 Force libavfilter to use a format different from @var{yuv420p} for the
4062 input to the vflip filter:
4064 noformat=pix_fmts=yuv420p,vflip
4068 Convert the input video to any of the formats not contained in the list:
4070 noformat=yuv420p|yuv444p|yuv410p
4076 Add noise on video input frame.
4078 The filter accepts the following options:
4086 Set noise seed for specific pixel component or all pixel components in case
4087 of @var{all_seed}. Default value is @code{123457}.
4089 @item all_strength, alls
4090 @item c0_strength, c0s
4091 @item c1_strength, c1s
4092 @item c2_strength, c2s
4093 @item c3_strength, c3s
4094 Set noise strength for specific pixel component or all pixel components in case
4095 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
4097 @item all_flags, allf
4102 Set pixel component flags or set flags for all components if @var{all_flags}.
4103 Available values for component flags are:
4106 averaged temporal noise (smoother)
4108 mix random noise with a (semi)regular pattern
4110 higher quality (slightly better looking, slightly slower)
4112 temporal noise (noise pattern changes between frames)
4114 uniform noise (gaussian otherwise)
4118 @subsection Examples
4120 Add temporal and uniform noise to input video:
4122 noise=alls=20:allf=t+u
4127 Pass the video source unchanged to the output.
4131 Apply video transform using libopencv.
4133 To enable this filter install libopencv library and headers and
4134 configure FFmpeg with @code{--enable-libopencv}.
4136 This filter accepts the following parameters:
4141 The name of the libopencv filter to apply.
4144 The parameters to pass to the libopencv filter. If not specified the default
4149 Refer to the official libopencv documentation for more precise
4151 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
4153 Follows the list of supported libopencv filters.
4158 Dilate an image by using a specific structuring element.
4159 This filter corresponds to the libopencv function @code{cvDilate}.
4161 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
4163 @var{struct_el} represents a structuring element, and has the syntax:
4164 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
4166 @var{cols} and @var{rows} represent the number of columns and rows of
4167 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
4168 point, and @var{shape} the shape for the structuring element, and
4169 can be one of the values "rect", "cross", "ellipse", "custom".
4171 If the value for @var{shape} is "custom", it must be followed by a
4172 string of the form "=@var{filename}". The file with name
4173 @var{filename} is assumed to represent a binary image, with each
4174 printable character corresponding to a bright pixel. When a custom
4175 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
4176 or columns and rows of the read file are assumed instead.
4178 The default value for @var{struct_el} is "3x3+0x0/rect".
4180 @var{nb_iterations} specifies the number of times the transform is
4181 applied to the image, and defaults to 1.
4183 Follow some example:
4185 # use the default values
4188 # dilate using a structuring element with a 5x5 cross, iterate two times
4189 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
4191 # read the shape from the file diamond.shape, iterate two times
4192 # the file diamond.shape may contain a pattern of characters like this:
4198 # the specified cols and rows are ignored (but not the anchor point coordinates)
4199 ocv=dilate:0x0+2x2/custom=diamond.shape|2
4204 Erode an image by using a specific structuring element.
4205 This filter corresponds to the libopencv function @code{cvErode}.
4207 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4208 with the same syntax and semantics as the @ref{dilate} filter.
4212 Smooth the input video.
4214 The filter takes the following parameters:
4215 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
4217 @var{type} is the type of smooth filter to apply, and can be one of
4218 the following values: "blur", "blur_no_scale", "median", "gaussian",
4219 "bilateral". The default value is "gaussian".
4221 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
4222 parameters whose meanings depend on smooth type. @var{param1} and
4223 @var{param2} accept integer positive values or 0, @var{param3} and
4224 @var{param4} accept float values.
4226 The default value for @var{param1} is 3, the default value for the
4227 other parameters is 0.
4229 These parameters correspond to the parameters assigned to the
4230 libopencv function @code{cvSmooth}.
4235 Overlay one video on top of another.
4237 It takes two inputs and one output, the first input is the "main"
4238 video on which the second input is overlayed.
4240 This filter accepts the following parameters:
4242 A description of the accepted options follows.
4247 Set the expression for the x and y coordinates of the overlayed video
4248 on the main video. Default value is "0" for both expressions. In case
4249 the expression is invalid, it is set to a huge value (meaning that the
4250 overlay will not be displayed within the output visible area).
4253 Set the expression which enables the overlay. If the evaluation is
4254 different from 0, the overlay is displayed on top of the input
4255 frame. By default it is "1".
4258 Set when the expressions for @option{x}, @option{y}, and
4259 @option{enable} are evaluated.
4261 It accepts the following values:
4264 only evaluate expressions once during the filter initialization or
4265 when a command is processed
4268 evaluate expressions for each incoming frame
4271 Default value is @samp{frame}.
4274 If set to 1, force the output to terminate when the shortest input
4275 terminates. Default value is 0.
4278 Set the format for the output video.
4280 It accepts the following values:
4292 Default value is @samp{yuv420}.
4294 @item rgb @emph{(deprecated)}
4295 If set to 1, force the filter to accept inputs in the RGB
4296 color space. Default value is 0. This option is deprecated, use
4297 @option{format} instead.
4300 The @option{x}, @option{y}, and @option{enable} expressions can
4301 contain the following parameters.
4306 main input width and height
4310 overlay input width and height
4314 the computed values for @var{x} and @var{y}. They are evaluated for
4319 horizontal and vertical chroma subsample values of the output
4320 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
4324 the number of input frame, starting from 0
4327 the position in the file of the input frame, NAN if unknown
4330 timestamp expressed in seconds, NAN if the input timestamp is unknown
4333 Note that the @var{n}, @var{pos}, @var{t} variables are available only
4334 when evaluation is done @emph{per frame}, and will evaluate to NAN
4335 when @option{eval} is set to @samp{init}.
4337 Be aware that frames are taken from each input video in timestamp
4338 order, hence, if their initial timestamps differ, it is a a good idea
4339 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4340 have them begin in the same zero timestamp, as it does the example for
4341 the @var{movie} filter.
4343 You can chain together more overlays but you should test the
4344 efficiency of such approach.
4346 @subsection Commands
4348 This filter supports the following command:
4351 Set the @option{x} option expression.
4354 Set the @option{y} option expression.
4357 Set the @option{enable} option expression.
4360 @subsection Examples
4364 Draw the overlay at 10 pixels from the bottom right corner of the main
4367 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4370 Using named options the example above becomes:
4372 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4376 Insert a transparent PNG logo in the bottom left corner of the input,
4377 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4379 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4383 Insert 2 different transparent PNG logos (second logo on bottom
4384 right corner) using the @command{ffmpeg} tool:
4386 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
4390 Add a transparent color layer on top of the main video, @code{WxH}
4391 must specify the size of the main input to the overlay filter:
4393 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
4397 Play an original video and a filtered version (here with the deshake
4398 filter) side by side using the @command{ffplay} tool:
4400 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4403 The above command is the same as:
4405 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4409 Make a sliding overlay appearing from the left to the right top part of the
4410 screen starting since time 2:
4412 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
4416 Compose output by putting two input videos side to side:
4418 ffmpeg -i left.avi -i right.avi -filter_complex "
4419 nullsrc=size=200x100 [background];
4420 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4421 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4422 [background][left] overlay=shortest=1 [background+left];
4423 [background+left][right] overlay=shortest=1:x=100 [left+right]
4428 Chain several overlays in cascade:
4430 nullsrc=s=200x200 [bg];
4431 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4432 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4433 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4434 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4435 [in3] null, [mid2] overlay=100:100 [out0]
4442 Add paddings to the input image, and place the original input at the
4443 given coordinates @var{x}, @var{y}.
4445 This filter accepts the following parameters:
4450 Specify an expression for the size of the output image with the
4451 paddings added. If the value for @var{width} or @var{height} is 0, the
4452 corresponding input size is used for the output.
4454 The @var{width} expression can reference the value set by the
4455 @var{height} expression, and vice versa.
4457 The default value of @var{width} and @var{height} is 0.
4461 Specify an expression for the offsets where to place the input image
4462 in the padded area with respect to the top/left border of the output
4465 The @var{x} expression can reference the value set by the @var{y}
4466 expression, and vice versa.
4468 The default value of @var{x} and @var{y} is 0.
4471 Specify the color of the padded area, it can be the name of a color
4472 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4474 The default value of @var{color} is "black".
4477 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4478 options are expressions containing the following constants:
4482 the input video width and height
4485 same as @var{in_w} and @var{in_h}
4488 the output width and height, that is the size of the padded area as
4489 specified by the @var{width} and @var{height} expressions
4492 same as @var{out_w} and @var{out_h}
4495 x and y offsets as specified by the @var{x} and @var{y}
4496 expressions, or NAN if not yet specified
4499 same as @var{iw} / @var{ih}
4502 input sample aspect ratio
4505 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4508 horizontal and vertical chroma subsample values. For example for the
4509 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4512 @subsection Examples
4516 Add paddings with color "violet" to the input video. Output video
4517 size is 640x480, the top-left corner of the input video is placed at
4520 pad=640:480:0:40:violet
4523 The example above is equivalent to the following command:
4525 pad=width=640:height=480:x=0:y=40:color=violet
4529 Pad the input to get an output with dimensions increased by 3/2,
4530 and put the input video at the center of the padded area:
4532 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4536 Pad the input to get a squared output with size equal to the maximum
4537 value between the input width and height, and put the input video at
4538 the center of the padded area:
4540 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4544 Pad the input to get a final w/h ratio of 16:9:
4546 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4550 In case of anamorphic video, in order to set the output display aspect
4551 correctly, it is necessary to use @var{sar} in the expression,
4552 according to the relation:
4554 (ih * X / ih) * sar = output_dar
4555 X = output_dar / sar
4558 Thus the previous example needs to be modified to:
4560 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4564 Double output size and put the input video in the bottom-right
4565 corner of the output padded area:
4567 pad="2*iw:2*ih:ow-iw:oh-ih"
4571 @section pixdesctest
4573 Pixel format descriptor test filter, mainly useful for internal
4574 testing. The output video should be equal to the input video.
4578 format=monow, pixdesctest
4581 can be used to test the monowhite pixel format descriptor definition.
4585 Enable the specified chain of postprocessing subfilters using libpostproc. This
4586 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4587 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4588 Each subfilter and some options have a short and a long name that can be used
4589 interchangeably, i.e. dr/dering are the same.
4591 The filters accept the following options:
4595 Set postprocessing subfilters string.
4598 All subfilters share common options to determine their scope:
4602 Honor the quality commands for this subfilter.
4605 Do chrominance filtering, too (default).
4608 Do luminance filtering only (no chrominance).
4611 Do chrominance filtering only (no luminance).
4614 These options can be appended after the subfilter name, separated by a '|'.
4616 Available subfilters are:
4619 @item hb/hdeblock[|difference[|flatness]]
4620 Horizontal deblocking filter
4623 Difference factor where higher values mean more deblocking (default: @code{32}).
4625 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4628 @item vb/vdeblock[|difference[|flatness]]
4629 Vertical deblocking filter
4632 Difference factor where higher values mean more deblocking (default: @code{32}).
4634 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4637 @item ha/hadeblock[|difference[|flatness]]
4638 Accurate horizontal deblocking filter
4641 Difference factor where higher values mean more deblocking (default: @code{32}).
4643 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4646 @item va/vadeblock[|difference[|flatness]]
4647 Accurate vertical deblocking filter
4650 Difference factor where higher values mean more deblocking (default: @code{32}).
4652 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4656 The horizontal and vertical deblocking filters share the difference and
4657 flatness values so you cannot set different horizontal and vertical
4662 Experimental horizontal deblocking filter
4665 Experimental vertical deblocking filter
4670 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
4673 larger -> stronger filtering
4675 larger -> stronger filtering
4677 larger -> stronger filtering
4680 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4683 Stretch luminance to @code{0-255}.
4686 @item lb/linblenddeint
4687 Linear blend deinterlacing filter that deinterlaces the given block by
4688 filtering all lines with a @code{(1 2 1)} filter.
4690 @item li/linipoldeint
4691 Linear interpolating deinterlacing filter that deinterlaces the given block by
4692 linearly interpolating every second line.
4694 @item ci/cubicipoldeint
4695 Cubic interpolating deinterlacing filter deinterlaces the given block by
4696 cubically interpolating every second line.
4698 @item md/mediandeint
4699 Median deinterlacing filter that deinterlaces the given block by applying a
4700 median filter to every second line.
4702 @item fd/ffmpegdeint
4703 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4704 second line with a @code{(-1 4 2 4 -1)} filter.
4707 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4708 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4710 @item fq/forceQuant[|quantizer]
4711 Overrides the quantizer table from the input with the constant quantizer you
4719 Default pp filter combination (@code{hb|a,vb|a,dr|a})
4722 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
4725 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
4728 @subsection Examples
4732 Apply horizontal and vertical deblocking, deringing and automatic
4733 brightness/contrast:
4739 Apply default filters without brightness/contrast correction:
4745 Apply default filters and temporal denoiser:
4747 pp=default/tmpnoise|1|2|3
4751 Apply deblocking on luminance only, and switch vertical deblocking on or off
4752 automatically depending on available CPU time:
4760 Suppress a TV station logo, using an image file to determine which
4761 pixels comprise the logo. It works by filling in the pixels that
4762 comprise the logo with neighboring pixels.
4764 This filter requires one argument which specifies the filter bitmap
4765 file, which can be any image format supported by libavformat. The
4766 width and height of the image file must match those of the video
4767 stream being processed.
4769 Pixels in the provided bitmap image with a value of zero are not
4770 considered part of the logo, non-zero pixels are considered part of
4771 the logo. If you use white (255) for the logo and black (0) for the
4772 rest, you will be safe. For making the filter bitmap, it is
4773 recommended to take a screen capture of a black frame with the logo
4774 visible, and then using a threshold filter followed by the erode
4775 filter once or twice.
4777 If needed, little splotches can be fixed manually. Remember that if
4778 logo pixels are not covered, the filter quality will be much
4779 reduced. Marking too many pixels as part of the logo does not hurt as
4780 much, but it will increase the amount of blurring needed to cover over
4781 the image and will destroy more information than necessary, and extra
4782 pixels will slow things down on a large logo.
4786 Scale (resize) the input video, using the libswscale library.
4788 The scale filter forces the output display aspect ratio to be the same
4789 of the input, by changing the output sample aspect ratio.
4791 This filter accepts a list of named options in the form of
4792 @var{key}=@var{value} pairs separated by ":". If the key for the first
4793 two options is not specified, the assumed keys for the first two
4794 values are @code{w} and @code{h}. If the first option has no key and
4795 can be interpreted like a video size specification, it will be used
4796 to set the video size.
4798 A description of the accepted options follows.
4803 default value is @code{iw}. See below
4804 for the list of accepted constants.
4807 Output video height.
4808 default value is @code{ih}.
4809 See below for the list of accepted constants.
4812 Set the interlacing. It accepts the following values:
4816 force interlaced aware scaling
4819 do not apply interlaced scaling
4822 select interlaced aware scaling depending on whether the source frames
4823 are flagged as interlaced or not
4826 Default value is @code{0}.
4829 Set libswscale scaling flags. If not explictly specified the filter
4830 applies a bilinear scaling algorithm.
4833 Set the video size, the value must be a valid abbreviation or in the
4834 form @var{width}x@var{height}.
4837 The values of the @var{w} and @var{h} options are expressions
4838 containing the following constants:
4842 the input width and height
4845 same as @var{in_w} and @var{in_h}
4848 the output (cropped) width and height
4851 same as @var{out_w} and @var{out_h}
4854 same as @var{iw} / @var{ih}
4857 input sample aspect ratio
4860 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4863 horizontal and vertical chroma subsample values. For example for the
4864 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4867 If the input image format is different from the format requested by
4868 the next filter, the scale filter will convert the input to the
4871 If the value for @var{w} or @var{h} is 0, the respective input
4872 size is used for the output.
4874 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
4875 respective output size, a value that maintains the aspect ratio of the input
4878 @subsection Examples
4882 Scale the input video to a size of 200x100:
4887 This is equivalent to:
4898 Specify a size abbreviation for the output size:
4903 which can also be written as:
4909 Scale the input to 2x:
4915 The above is the same as:
4921 Scale the input to 2x with forced interlaced scaling:
4923 scale=2*iw:2*ih:interl=1
4927 Scale the input to half size:
4933 Increase the width, and set the height to the same size:
4939 Seek for Greek harmony:
4946 Increase the height, and set the width to 3/2 of the height:
4948 scale=w=3/2*oh:h=3/5*ih
4952 Increase the size, but make the size a multiple of the chroma
4955 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4959 Increase the width to a maximum of 500 pixels, keep the same input
4962 scale=w='min(500\, iw*3/2):h=-1'
4966 @section separatefields
4968 The @code{separatefields} takes a frame-based video input and splits
4969 each frame into its components fields, producing a new half height clip
4970 with twice the frame rate and twice the frame count.
4972 This filter use field-dominance information in frame to decide which
4973 of each pair of fields to place first in the output.
4974 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
4976 @section setdar, setsar
4978 The @code{setdar} filter sets the Display Aspect Ratio for the filter
4981 This is done by changing the specified Sample (aka Pixel) Aspect
4982 Ratio, according to the following equation:
4984 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
4987 Keep in mind that the @code{setdar} filter does not modify the pixel
4988 dimensions of the video frame. Also the display aspect ratio set by
4989 this filter may be changed by later filters in the filterchain,
4990 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
4993 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
4994 the filter output video.
4996 Note that as a consequence of the application of this filter, the
4997 output display aspect ratio will change according to the equation
5000 Keep in mind that the sample aspect ratio set by the @code{setsar}
5001 filter may be changed by later filters in the filterchain, e.g. if
5002 another "setsar" or a "setdar" filter is applied.
5004 The @code{setdar} and @code{setsar} filters accept a string in the
5005 form @var{num}:@var{den} expressing an aspect ratio, or the following
5006 named options, expressed as a sequence of @var{key}=@var{value} pairs,
5011 Set the maximum integer value to use for expressing numerator and
5012 denominator when reducing the expressed aspect ratio to a rational.
5013 Default value is @code{100}.
5015 @item r, ratio, dar, sar:
5016 Set the aspect ratio used by the filter.
5018 The parameter can be a floating point number string, an expression, or
5019 a string of the form @var{num}:@var{den}, where @var{num} and
5020 @var{den} are the numerator and denominator of the aspect ratio. If
5021 the parameter is not specified, it is assumed the value "0".
5022 In case the form "@var{num}:@var{den}" the @code{:} character should
5026 If the keys are omitted in the named options list, the specifed values
5027 are assumed to be @var{ratio} and @var{max} in that order.
5029 For example to change the display aspect ratio to 16:9, specify:
5032 # the above is equivalent to
5038 To change the sample aspect ratio to 10:11, specify:
5041 # the above is equivalent to
5045 To set a display aspect ratio of 16:9, and specify a maximum integer value of
5046 1000 in the aspect ratio reduction, use the command:
5048 setdar=ratio='16:9':max=1000
5054 Force field for the output video frame.
5056 The @code{setfield} filter marks the interlace type field for the
5057 output frames. It does not change the input frame, but only sets the
5058 corresponding property, which affects how the frame is treated by
5059 following filters (e.g. @code{fieldorder} or @code{yadif}).
5061 The filter accepts the following options:
5066 Available values are:
5070 Keep the same field property.
5073 Mark the frame as bottom-field-first.
5076 Mark the frame as top-field-first.
5079 Mark the frame as progressive.
5085 Show a line containing various information for each input video frame.
5086 The input video is not modified.
5088 The shown line contains a sequence of key/value pairs of the form
5089 @var{key}:@var{value}.
5091 A description of each shown parameter follows:
5095 sequential number of the input frame, starting from 0
5098 Presentation TimeStamp of the input frame, expressed as a number of
5099 time base units. The time base unit depends on the filter input pad.
5102 Presentation TimeStamp of the input frame, expressed as a number of
5106 position of the frame in the input stream, -1 if this information in
5107 unavailable and/or meaningless (for example in case of synthetic video)
5113 sample aspect ratio of the input frame, expressed in the form
5117 size of the input frame, expressed in the form
5118 @var{width}x@var{height}
5121 interlaced mode ("P" for "progressive", "T" for top field first, "B"
5122 for bottom field first)
5125 1 if the frame is a key frame, 0 otherwise
5128 picture type of the input frame ("I" for an I-frame, "P" for a
5129 P-frame, "B" for a B-frame, "?" for unknown type).
5130 Check also the documentation of the @code{AVPictureType} enum and of
5131 the @code{av_get_picture_type_char} function defined in
5132 @file{libavutil/avutil.h}.
5135 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
5137 @item plane_checksum
5138 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
5139 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
5144 Blur the input video without impacting the outlines.
5146 The filter accepts the following options:
5149 @item luma_radius, lr
5150 Set the luma radius. The option value must be a float number in
5151 the range [0.1,5.0] that specifies the variance of the gaussian filter
5152 used to blur the image (slower if larger). Default value is 1.0.
5154 @item luma_strength, ls
5155 Set the luma strength. The option value must be a float number
5156 in the range [-1.0,1.0] that configures the blurring. A value included
5157 in [0.0,1.0] will blur the image whereas a value included in
5158 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5160 @item luma_threshold, lt
5161 Set the luma threshold used as a coefficient to determine
5162 whether a pixel should be blurred or not. The option value must be an
5163 integer in the range [-30,30]. A value of 0 will filter all the image,
5164 a value included in [0,30] will filter flat areas and a value included
5165 in [-30,0] will filter edges. Default value is 0.
5167 @item chroma_radius, cr
5168 Set the chroma radius. The option value must be a float number in
5169 the range [0.1,5.0] that specifies the variance of the gaussian filter
5170 used to blur the image (slower if larger). Default value is 1.0.
5172 @item chroma_strength, cs
5173 Set the chroma strength. The option value must be a float number
5174 in the range [-1.0,1.0] that configures the blurring. A value included
5175 in [0.0,1.0] will blur the image whereas a value included in
5176 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5178 @item chroma_threshold, ct
5179 Set the chroma threshold used as a coefficient to determine
5180 whether a pixel should be blurred or not. The option value must be an
5181 integer in the range [-30,30]. A value of 0 will filter all the image,
5182 a value included in [0,30] will filter flat areas and a value included
5183 in [-30,0] will filter edges. Default value is 0.
5186 If a chroma option is not explicitly set, the corresponding luma value
5191 Convert between different stereoscopic image formats.
5193 The filters accept the following options:
5197 Set stereoscopic image format of input.
5199 Available values for input image formats are:
5202 side by side parallel (left eye left, right eye right)
5205 side by side crosseye (right eye left, left eye right)
5208 side by side parallel with half width resolution
5209 (left eye left, right eye right)
5212 side by side crosseye with half width resolution
5213 (right eye left, left eye right)
5216 above-below (left eye above, right eye below)
5219 above-below (right eye above, left eye below)
5222 above-below with half height resolution
5223 (left eye above, right eye below)
5226 above-below with half height resolution
5227 (right eye above, left eye below)
5229 Default value is @samp{sbsl}.
5233 Set stereoscopic image format of output.
5235 Available values for output image formats are all the input formats as well as:
5238 anaglyph red/blue gray
5239 (red filter on left eye, blue filter on right eye)
5242 anaglyph red/green gray
5243 (red filter on left eye, green filter on right eye)
5246 anaglyph red/cyan gray
5247 (red filter on left eye, cyan filter on right eye)
5250 anaglyph red/cyan half colored
5251 (red filter on left eye, cyan filter on right eye)
5254 anaglyph red/cyan color
5255 (red filter on left eye, cyan filter on right eye)
5258 anaglyph red/cyan color optimized with the least squares projection of dubois
5259 (red filter on left eye, cyan filter on right eye)
5262 anaglyph green/magenta gray
5263 (green filter on left eye, magenta filter on right eye)
5266 anaglyph green/magenta half colored
5267 (green filter on left eye, magenta filter on right eye)
5270 anaglyph green/magenta colored
5271 (green filter on left eye, magenta filter on right eye)
5274 anaglyph green/magenta color optimized with the least squares projection of dubois
5275 (green filter on left eye, magenta filter on right eye)
5278 anaglyph yellow/blue gray
5279 (yellow filter on left eye, blue filter on right eye)
5282 anaglyph yellow/blue half colored
5283 (yellow filter on left eye, blue filter on right eye)
5286 anaglyph yellow/blue colored
5287 (yellow filter on left eye, blue filter on right eye)
5290 anaglyph yellow/blue color optimized with the least squares projection of dubois
5291 (yellow filter on left eye, blue filter on right eye)
5294 interleaved rows (left eye has top row, right eye starts on next row)
5297 interleaved rows (right eye has top row, left eye starts on next row)
5300 mono output (left eye only)
5303 mono output (right eye only)
5306 Default value is @samp{arcd}.
5312 Draw subtitles on top of input video using the libass library.
5314 To enable compilation of this filter you need to configure FFmpeg with
5315 @code{--enable-libass}. This filter also requires a build with libavcodec and
5316 libavformat to convert the passed subtitles file to ASS (Advanced Substation
5317 Alpha) subtitles format.
5319 The filter accepts the following options:
5323 Set the filename of the subtitle file to read. It must be specified.
5326 Specify the size of the original video, the video for which the ASS file
5327 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
5328 necessary to correctly scale the fonts if the aspect ratio has been changed.
5331 Set subtitles input character encoding. @code{subtitles} filter only. Only
5332 useful if not UTF-8.
5335 If the first key is not specified, it is assumed that the first value
5336 specifies the @option{filename}.
5338 For example, to render the file @file{sub.srt} on top of the input
5339 video, use the command:
5344 which is equivalent to:
5346 subtitles=filename=sub.srt
5351 Split input video into several identical outputs.
5353 The filter accepts a single parameter which specifies the number of outputs. If
5354 unspecified, it defaults to 2.
5358 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
5360 will create 5 copies of the input video.
5364 [in] split [splitout1][splitout2];
5365 [splitout1] crop=100:100:0:0 [cropout];
5366 [splitout2] pad=200:200:100:100 [padout];
5369 will create two separate outputs from the same input, one cropped and
5374 Scale the input by 2x and smooth using the Super2xSaI (Scale and
5375 Interpolate) pixel art scaling algorithm.
5377 Useful for enlarging pixel art images without reducing sharpness.
5383 Select the most representative frame in a given sequence of consecutive frames.
5385 The filter accepts the following options:
5389 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
5390 will pick one of them, and then handle the next batch of @var{n} frames until
5391 the end. Default is @code{100}.
5394 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
5395 value will result in a higher memory usage, so a high value is not recommended.
5397 @subsection Examples
5401 Extract one picture each 50 frames:
5407 Complete example of a thumbnail creation with @command{ffmpeg}:
5409 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
5415 Tile several successive frames together.
5417 The filter accepts the following options:
5422 Set the grid size (i.e. the number of lines and columns) in the form
5426 Set the maximum number of frames to render in the given area. It must be less
5427 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
5428 the area will be used.
5431 Set the outer border margin in pixels.
5434 Set the inner border thickness (i.e. the number of pixels between frames). For
5435 more advanced padding options (such as having different values for the edges),
5436 refer to the pad video filter.
5440 @subsection Examples
5444 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
5446 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
5448 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
5449 duplicating each output frame to accomodate the originally detected frame
5453 Display @code{5} pictures in an area of @code{3x2} frames,
5454 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
5455 mixed flat and named options:
5457 tile=3x2:nb_frames=5:padding=7:margin=2
5463 Perform various types of temporal field interlacing.
5465 Frames are counted starting from 1, so the first input frame is
5468 The filter accepts the following options:
5473 Specify the mode of the interlacing. This option can also be specified
5474 as a value alone. See below for a list of values for this option.
5476 Available values are:
5480 Move odd frames into the upper field, even into the lower field,
5481 generating a double height frame at half frame rate.
5484 Only output even frames, odd frames are dropped, generating a frame with
5485 unchanged height at half frame rate.
5488 Only output odd frames, even frames are dropped, generating a frame with
5489 unchanged height at half frame rate.
5492 Expand each frame to full height, but pad alternate lines with black,
5493 generating a frame with double height at the same input frame rate.
5495 @item interleave_top, 4
5496 Interleave the upper field from odd frames with the lower field from
5497 even frames, generating a frame with unchanged height at half frame rate.
5499 @item interleave_bottom, 5
5500 Interleave the lower field from odd frames with the upper field from
5501 even frames, generating a frame with unchanged height at half frame rate.
5503 @item interlacex2, 6
5504 Double frame rate with unchanged height. Frames are inserted each
5505 containing the second temporal field from the previous input frame and
5506 the first temporal field from the next input frame. This mode relies on
5507 the top_field_first flag. Useful for interlaced video displays with no
5508 field synchronisation.
5511 Numeric values are deprecated but are accepted for backward
5512 compatibility reasons.
5514 Default mode is @code{merge}.
5517 Specify flags influencing the filter process.
5519 Available value for @var{flags} is:
5522 @item low_pass_filter, vlfp
5523 Enable vertical low-pass filtering in the filter.
5524 Vertical low-pass filtering is required when creating an interlaced
5525 destination from a progressive source which contains high-frequency
5526 vertical detail. Filtering will reduce interlace 'twitter' and Moire
5529 Vertical low-pass filtering can only be enabled for @option{mode}
5530 @var{interleave_top} and @var{interleave_bottom}.
5537 Transpose rows with columns in the input video and optionally flip it.
5539 This filter accepts the following options:
5544 The direction of the transpose.
5547 @item 0, 4, cclock_flip
5548 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
5556 Rotate by 90 degrees clockwise, that is:
5564 Rotate by 90 degrees counterclockwise, that is:
5571 @item 3, 7, clock_flip
5572 Rotate by 90 degrees clockwise and vertically flip, that is:
5580 For values between 4-7, the transposition is only done if the input
5581 video geometry is portrait and not landscape. These values are
5582 deprecated, the @code{passthrough} option should be used instead.
5585 Do not apply the transposition if the input geometry matches the one
5586 specified by the specified value. It accepts the following values:
5589 Always apply transposition.
5591 Preserve portrait geometry (when @var{height} >= @var{width}).
5593 Preserve landscape geometry (when @var{width} >= @var{height}).
5596 Default value is @code{none}.
5599 For example to rotate by 90 degrees clockwise and preserve portrait
5602 transpose=dir=1:passthrough=portrait
5605 The command above can also be specified as:
5607 transpose=1:portrait
5612 Sharpen or blur the input video.
5614 It accepts the following parameters:
5617 @item luma_msize_x, lx
5618 @item chroma_msize_x, cx
5619 Set the luma/chroma matrix horizontal size. It must be an odd integer
5620 between 3 and 63, default value is 5.
5622 @item luma_msize_y, ly
5623 @item chroma_msize_y, cy
5624 Set the luma/chroma matrix vertical size. It must be an odd integer
5625 between 3 and 63, default value is 5.
5627 @item luma_amount, la
5628 @item chroma_amount, ca
5629 Set the luma/chroma effect strength. It can be a float number,
5630 reasonable values lay between -1.5 and 1.5.
5632 Negative values will blur the input video, while positive values will
5633 sharpen it, a value of zero will disable the effect.
5635 Default value is 1.0 for @option{luma_amount}, 0.0 for
5636 @option{chroma_amount}.
5639 All parameters are optional and default to the
5640 equivalent of the string '5:5:1.0:5:5:0.0'.
5642 @subsection Examples
5646 Apply strong luma sharpen effect:
5648 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
5652 Apply strong blur of both luma and chroma parameters:
5654 unsharp=7:7:-2:7:7:-2
5660 Flip the input video vertically.
5663 ffmpeg -i in.avi -vf "vflip" out.avi
5668 Deinterlace the input video ("yadif" means "yet another deinterlacing
5671 This filter accepts the following options:
5677 The interlacing mode to adopt, accepts one of the following values:
5681 output 1 frame for each frame
5683 output 1 frame for each field
5684 @item 2, send_frame_nospatial
5685 like @code{send_frame} but skip spatial interlacing check
5686 @item 3, send_field_nospatial
5687 like @code{send_field} but skip spatial interlacing check
5690 Default value is @code{send_frame}.
5693 The picture field parity assumed for the input interlaced video, accepts one of
5694 the following values:
5698 assume top field first
5700 assume bottom field first
5702 enable automatic detection
5705 Default value is @code{auto}.
5706 If interlacing is unknown or decoder does not export this information,
5707 top field first will be assumed.
5710 Specify which frames to deinterlace. Accept one of the following
5715 deinterlace all frames
5717 only deinterlace frames marked as interlaced
5720 Default value is @code{all}.
5723 @c man end VIDEO FILTERS
5725 @chapter Video Sources
5726 @c man begin VIDEO SOURCES
5728 Below is a description of the currently available video sources.
5732 Buffer video frames, and make them available to the filter chain.
5734 This source is mainly intended for a programmatic use, in particular
5735 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5737 It accepts a list of options in the form of @var{key}=@var{value} pairs
5738 separated by ":". A description of the accepted options follows.
5743 Specify the size (width and height) of the buffered video frames.
5746 A string representing the pixel format of the buffered video frames.
5747 It may be a number corresponding to a pixel format, or a pixel format
5751 Specify the timebase assumed by the timestamps of the buffered frames.
5754 Specify the frame rate expected for the video stream.
5757 Specify the sample aspect ratio assumed by the video frames.
5760 Specify the optional parameters to be used for the scale filter which
5761 is automatically inserted when an input change is detected in the
5762 input size or format.
5767 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
5770 will instruct the source to accept video frames with size 320x240 and
5771 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5772 square pixels (1:1 sample aspect ratio).
5773 Since the pixel format with name "yuv410p" corresponds to the number 6
5774 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5775 this example corresponds to:
5777 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5780 Alternatively, the options can be specified as a flat string, but this
5781 syntax is deprecated:
5783 @var{width}:@var{height}:@var{pix_fmt}:@var{time_base.num}:@var{time_base.den}:@var{pixel_aspect.num}:@var{pixel_aspect.den}[:@var{sws_param}]
5787 Create a pattern generated by an elementary cellular automaton.
5789 The initial state of the cellular automaton can be defined through the
5790 @option{filename}, and @option{pattern} options. If such options are
5791 not specified an initial state is created randomly.
5793 At each new frame a new row in the video is filled with the result of
5794 the cellular automaton next generation. The behavior when the whole
5795 frame is filled is defined by the @option{scroll} option.
5797 This source accepts the following options:
5801 Read the initial cellular automaton state, i.e. the starting row, from
5803 In the file, each non-whitespace character is considered an alive
5804 cell, a newline will terminate the row, and further characters in the
5805 file will be ignored.
5808 Read the initial cellular automaton state, i.e. the starting row, from
5809 the specified string.
5811 Each non-whitespace character in the string is considered an alive
5812 cell, a newline will terminate the row, and further characters in the
5813 string will be ignored.
5816 Set the video rate, that is the number of frames generated per second.
5819 @item random_fill_ratio, ratio
5820 Set the random fill ratio for the initial cellular automaton row. It
5821 is a floating point number value ranging from 0 to 1, defaults to
5824 This option is ignored when a file or a pattern is specified.
5826 @item random_seed, seed
5827 Set the seed for filling randomly the initial row, must be an integer
5828 included between 0 and UINT32_MAX. If not specified, or if explicitly
5829 set to -1, the filter will try to use a good random seed on a best
5833 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5834 Default value is 110.
5837 Set the size of the output video.
5839 If @option{filename} or @option{pattern} is specified, the size is set
5840 by default to the width of the specified initial state row, and the
5841 height is set to @var{width} * PHI.
5843 If @option{size} is set, it must contain the width of the specified
5844 pattern string, and the specified pattern will be centered in the
5847 If a filename or a pattern string is not specified, the size value
5848 defaults to "320x518" (used for a randomly generated initial state).
5851 If set to 1, scroll the output upward when all the rows in the output
5852 have been already filled. If set to 0, the new generated row will be
5853 written over the top row just after the bottom row is filled.
5856 @item start_full, full
5857 If set to 1, completely fill the output with generated rows before
5858 outputting the first frame.
5859 This is the default behavior, for disabling set the value to 0.
5862 If set to 1, stitch the left and right row edges together.
5863 This is the default behavior, for disabling set the value to 0.
5866 @subsection Examples
5870 Read the initial state from @file{pattern}, and specify an output of
5873 cellauto=f=pattern:s=200x400
5877 Generate a random initial row with a width of 200 cells, with a fill
5880 cellauto=ratio=2/3:s=200x200
5884 Create a pattern generated by rule 18 starting by a single alive cell
5885 centered on an initial row with width 100:
5887 cellauto=p=@@:s=100x400:full=0:rule=18
5891 Specify a more elaborated initial pattern:
5893 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5900 Generate a Mandelbrot set fractal, and progressively zoom towards the
5901 point specified with @var{start_x} and @var{start_y}.
5903 This source accepts the following options:
5908 Set the terminal pts value. Default value is 400.
5911 Set the terminal scale value.
5912 Must be a floating point value. Default value is 0.3.
5915 Set the inner coloring mode, that is the algorithm used to draw the
5916 Mandelbrot fractal internal region.
5918 It shall assume one of the following values:
5923 Show time until convergence.
5925 Set color based on point closest to the origin of the iterations.
5930 Default value is @var{mincol}.
5933 Set the bailout value. Default value is 10.0.
5936 Set the maximum of iterations performed by the rendering
5937 algorithm. Default value is 7189.
5940 Set outer coloring mode.
5941 It shall assume one of following values:
5943 @item iteration_count
5944 Set iteration cound mode.
5945 @item normalized_iteration_count
5946 set normalized iteration count mode.
5948 Default value is @var{normalized_iteration_count}.
5951 Set frame rate, expressed as number of frames per second. Default
5955 Set frame size. Default value is "640x480".
5958 Set the initial scale value. Default value is 3.0.
5961 Set the initial x position. Must be a floating point value between
5962 -100 and 100. Default value is -0.743643887037158704752191506114774.
5965 Set the initial y position. Must be a floating point value between
5966 -100 and 100. Default value is -0.131825904205311970493132056385139.
5971 Generate various test patterns, as generated by the MPlayer test filter.
5973 The size of the generated video is fixed, and is 256x256.
5974 This source is useful in particular for testing encoding features.
5976 This source accepts the following options:
5981 Specify the frame rate of the sourced video, as the number of frames
5982 generated per second. It has to be a string in the format
5983 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5984 number or a valid video frame rate abbreviation. The default value is
5988 Set the video duration of the sourced video. The accepted syntax is:
5993 See also the function @code{av_parse_time()}.
5995 If not specified, or the expressed duration is negative, the video is
5996 supposed to be generated forever.
6000 Set the number or the name of the test to perform. Supported tests are:
6015 Default value is "all", which will cycle through the list of all tests.
6018 For example the following:
6023 will generate a "dc_luma" test pattern.
6027 Provide a frei0r source.
6029 To enable compilation of this filter you need to install the frei0r
6030 header and configure FFmpeg with @code{--enable-frei0r}.
6032 This source accepts the following options:
6037 The size of the video to generate, may be a string of the form
6038 @var{width}x@var{height} or a frame size abbreviation.
6041 Framerate of the generated video, may be a string of the form
6042 @var{num}/@var{den} or a frame rate abbreviation.
6045 The name to the frei0r source to load. For more information regarding frei0r and
6046 how to set the parameters read the section @ref{frei0r} in the description of
6050 A '|'-separated list of parameters to pass to the frei0r source.
6054 For example, to generate a frei0r partik0l source with size 200x200
6055 and frame rate 10 which is overlayed on the overlay filter main input:
6057 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
6062 Generate a life pattern.
6064 This source is based on a generalization of John Conway's life game.
6066 The sourced input represents a life grid, each pixel represents a cell
6067 which can be in one of two possible states, alive or dead. Every cell
6068 interacts with its eight neighbours, which are the cells that are
6069 horizontally, vertically, or diagonally adjacent.
6071 At each interaction the grid evolves according to the adopted rule,
6072 which specifies the number of neighbor alive cells which will make a
6073 cell stay alive or born. The @option{rule} option allows to specify
6076 This source accepts the following options:
6080 Set the file from which to read the initial grid state. In the file,
6081 each non-whitespace character is considered an alive cell, and newline
6082 is used to delimit the end of each row.
6084 If this option is not specified, the initial grid is generated
6088 Set the video rate, that is the number of frames generated per second.
6091 @item random_fill_ratio, ratio
6092 Set the random fill ratio for the initial random grid. It is a
6093 floating point number value ranging from 0 to 1, defaults to 1/PHI.
6094 It is ignored when a file is specified.
6096 @item random_seed, seed
6097 Set the seed for filling the initial random grid, must be an integer
6098 included between 0 and UINT32_MAX. If not specified, or if explicitly
6099 set to -1, the filter will try to use a good random seed on a best
6105 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
6106 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
6107 @var{NS} specifies the number of alive neighbor cells which make a
6108 live cell stay alive, and @var{NB} the number of alive neighbor cells
6109 which make a dead cell to become alive (i.e. to "born").
6110 "s" and "b" can be used in place of "S" and "B", respectively.
6112 Alternatively a rule can be specified by an 18-bits integer. The 9
6113 high order bits are used to encode the next cell state if it is alive
6114 for each number of neighbor alive cells, the low order bits specify
6115 the rule for "borning" new cells. Higher order bits encode for an
6116 higher number of neighbor cells.
6117 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
6118 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
6120 Default value is "S23/B3", which is the original Conway's game of life
6121 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
6122 cells, and will born a new cell if there are three alive cells around
6126 Set the size of the output video.
6128 If @option{filename} is specified, the size is set by default to the
6129 same size of the input file. If @option{size} is set, it must contain
6130 the size specified in the input file, and the initial grid defined in
6131 that file is centered in the larger resulting area.
6133 If a filename is not specified, the size value defaults to "320x240"
6134 (used for a randomly generated initial grid).
6137 If set to 1, stitch the left and right grid edges together, and the
6138 top and bottom edges also. Defaults to 1.
6141 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
6142 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
6143 value from 0 to 255.
6146 Set the color of living (or new born) cells.
6149 Set the color of dead cells. If @option{mold} is set, this is the first color
6150 used to represent a dead cell.
6153 Set mold color, for definitely dead and moldy cells.
6156 @subsection Examples
6160 Read a grid from @file{pattern}, and center it on a grid of size
6163 life=f=pattern:s=300x300
6167 Generate a random grid of size 200x200, with a fill ratio of 2/3:
6169 life=ratio=2/3:s=200x200
6173 Specify a custom rule for evolving a randomly generated grid:
6179 Full example with slow death effect (mold) using @command{ffplay}:
6181 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
6185 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
6187 The @code{color} source provides an uniformly colored input.
6189 The @code{nullsrc} source returns unprocessed video frames. It is
6190 mainly useful to be employed in analysis / debugging tools, or as the
6191 source for filters which ignore the input data.
6193 The @code{rgbtestsrc} source generates an RGB test pattern useful for
6194 detecting RGB vs BGR issues. You should see a red, green and blue
6195 stripe from top to bottom.
6197 The @code{smptebars} source generates a color bars pattern, based on
6198 the SMPTE Engineering Guideline EG 1-1990.
6200 The @code{testsrc} source generates a test video pattern, showing a
6201 color pattern, a scrolling gradient and a timestamp. This is mainly
6202 intended for testing purposes.
6204 The sources accept the following options:
6209 Specify the color of the source, only used in the @code{color}
6210 source. It can be the name of a color (case insensitive match) or a
6211 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
6212 default value is "black".
6215 Specify the size of the sourced video, it may be a string of the form
6216 @var{width}x@var{height}, or the name of a size abbreviation. The
6217 default value is "320x240".
6220 Specify the frame rate of the sourced video, as the number of frames
6221 generated per second. It has to be a string in the format
6222 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6223 number or a valid video frame rate abbreviation. The default value is
6227 Set the sample aspect ratio of the sourced video.
6230 Set the video duration of the sourced video. The accepted syntax is:
6232 [-]HH[:MM[:SS[.m...]]]
6235 See also the function @code{av_parse_time()}.
6237 If not specified, or the expressed duration is negative, the video is
6238 supposed to be generated forever.
6241 Set the number of decimals to show in the timestamp, only used in the
6242 @code{testsrc} source.
6244 The displayed timestamp value will correspond to the original
6245 timestamp value multiplied by the power of 10 of the specified
6246 value. Default value is 0.
6249 For example the following:
6251 testsrc=duration=5.3:size=qcif:rate=10
6254 will generate a video with a duration of 5.3 seconds, with size
6255 176x144 and a frame rate of 10 frames per second.
6257 The following graph description will generate a red source
6258 with an opacity of 0.2, with size "qcif" and a frame rate of 10
6261 color=c=red@@0.2:s=qcif:r=10
6264 If the input content is to be ignored, @code{nullsrc} can be used. The
6265 following command generates noise in the luminance plane by employing
6266 the @code{geq} filter:
6268 nullsrc=s=256x256, geq=random(1)*255:128:128
6271 @c man end VIDEO SOURCES
6273 @chapter Video Sinks
6274 @c man begin VIDEO SINKS
6276 Below is a description of the currently available video sinks.
6280 Buffer video frames, and make them available to the end of the filter
6283 This sink is mainly intended for a programmatic use, in particular
6284 through the interface defined in @file{libavfilter/buffersink.h}.
6286 It does not require a string parameter in input, but you need to
6287 specify a pointer to a list of supported pixel formats terminated by
6288 -1 in the opaque parameter provided to @code{avfilter_init_filter}
6289 when initializing this sink.
6293 Null video sink, do absolutely nothing with the input video. It is
6294 mainly useful as a template and to be employed in analysis / debugging
6297 @c man end VIDEO SINKS
6299 @chapter Multimedia Filters
6300 @c man begin MULTIMEDIA FILTERS
6302 Below is a description of the currently available multimedia filters.
6304 @section aperms, perms
6306 Set read/write permissions for the output frames.
6308 These filters are mainly aimed at developers to test direct path in the
6309 following filter in the filtergraph.
6311 The filters accept the following options:
6315 Select the permissions mode.
6317 It accepts the following values:
6320 Do nothing. This is the default.
6322 Set all the output frames read-only.
6324 Set all the output frames directly writable.
6326 Make the frame read-only if writable, and writable if read-only.
6328 Set each output frame read-only or writable randomly.
6332 Set the seed for the @var{random} mode, must be an integer included between
6333 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
6334 @code{-1}, the filter will try to use a good random seed on a best effort
6338 Note: in case of auto-inserted filter between the permission filter and the
6339 following one, the permission might not be received as expected in that
6340 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
6341 perms/aperms filter can avoid this problem.
6344 Add a phasing effect to the input audio.
6346 A phaser filter creates series of peaks and troughs in the frequency spectrum.
6347 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
6349 A description of the accepted parameters follows.
6353 Set input gain. Default is 0.4.
6356 Set output gain. Default is 0.74
6359 Set delay in milliseconds. Default is 3.0.
6362 Set decay. Default is 0.4.
6365 Set modulation speed in Hz. Default is 0.5.
6368 Set modulation type. Default is triangular.
6370 It accepts the following values:
6377 @section aselect, select
6378 Select frames to pass in output.
6380 This filter accepts the following options:
6385 An expression, which is evaluated for each input frame. If the expression is
6386 evaluated to a non-zero value, the frame is selected and passed to the output,
6387 otherwise it is discarded.
6391 The expression can contain the following constants:
6395 the sequential number of the filtered frame, starting from 0
6398 the sequential number of the selected frame, starting from 0
6400 @item prev_selected_n
6401 the sequential number of the last selected frame, NAN if undefined
6404 timebase of the input timestamps
6407 the PTS (Presentation TimeStamp) of the filtered video frame,
6408 expressed in @var{TB} units, NAN if undefined
6411 the PTS (Presentation TimeStamp) of the filtered video frame,
6412 expressed in seconds, NAN if undefined
6415 the PTS of the previously filtered video frame, NAN if undefined
6417 @item prev_selected_pts
6418 the PTS of the last previously filtered video frame, NAN if undefined
6420 @item prev_selected_t
6421 the PTS of the last previously selected video frame, NAN if undefined
6424 the PTS of the first video frame in the video, NAN if undefined
6427 the time of the first video frame in the video, NAN if undefined
6429 @item pict_type @emph{(video only)}
6430 the type of the filtered frame, can assume one of the following
6442 @item interlace_type @emph{(video only)}
6443 the frame interlace type, can assume one of the following values:
6446 the frame is progressive (not interlaced)
6448 the frame is top-field-first
6450 the frame is bottom-field-first
6453 @item consumed_sample_n @emph{(audio only)}
6454 the number of selected samples before the current frame
6456 @item samples_n @emph{(audio only)}
6457 the number of samples in the current frame
6459 @item sample_rate @emph{(audio only)}
6460 the input sample rate
6463 1 if the filtered frame is a key-frame, 0 otherwise
6466 the position in the file of the filtered frame, -1 if the information
6467 is not available (e.g. for synthetic video)
6469 @item scene @emph{(video only)}
6470 value between 0 and 1 to indicate a new scene; a low value reflects a low
6471 probability for the current frame to introduce a new scene, while a higher
6472 value means the current frame is more likely to be one (see the example below)
6476 The default value of the select expression is "1".
6478 @subsection Examples
6482 Select all frames in input:
6487 The example above is the same as:
6499 Select only I-frames:
6501 select='eq(pict_type\,I)'
6505 Select one frame every 100:
6507 select='not(mod(n\,100))'
6511 Select only frames contained in the 10-20 time interval:
6513 select='gte(t\,10)*lte(t\,20)'
6517 Select only I frames contained in the 10-20 time interval:
6519 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
6523 Select frames with a minimum distance of 10 seconds:
6525 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
6529 Use aselect to select only audio frames with samples number > 100:
6531 aselect='gt(samples_n\,100)'
6535 Create a mosaic of the first scenes:
6537 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
6540 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
6544 @section asendcmd, sendcmd
6546 Send commands to filters in the filtergraph.
6548 These filters read commands to be sent to other filters in the
6551 @code{asendcmd} must be inserted between two audio filters,
6552 @code{sendcmd} must be inserted between two video filters, but apart
6553 from that they act the same way.
6555 The specification of commands can be provided in the filter arguments
6556 with the @var{commands} option, or in a file specified by the
6557 @var{filename} option.
6559 These filters accept the following options:
6562 Set the commands to be read and sent to the other filters.
6564 Set the filename of the commands to be read and sent to the other
6568 @subsection Commands syntax
6570 A commands description consists of a sequence of interval
6571 specifications, comprising a list of commands to be executed when a
6572 particular event related to that interval occurs. The occurring event
6573 is typically the current frame time entering or leaving a given time
6576 An interval is specified by the following syntax:
6578 @var{START}[-@var{END}] @var{COMMANDS};
6581 The time interval is specified by the @var{START} and @var{END} times.
6582 @var{END} is optional and defaults to the maximum time.
6584 The current frame time is considered within the specified interval if
6585 it is included in the interval [@var{START}, @var{END}), that is when
6586 the time is greater or equal to @var{START} and is lesser than
6589 @var{COMMANDS} consists of a sequence of one or more command
6590 specifications, separated by ",", relating to that interval. The
6591 syntax of a command specification is given by:
6593 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
6596 @var{FLAGS} is optional and specifies the type of events relating to
6597 the time interval which enable sending the specified command, and must
6598 be a non-null sequence of identifier flags separated by "+" or "|" and
6599 enclosed between "[" and "]".
6601 The following flags are recognized:
6604 The command is sent when the current frame timestamp enters the
6605 specified interval. In other words, the command is sent when the
6606 previous frame timestamp was not in the given interval, and the
6610 The command is sent when the current frame timestamp leaves the
6611 specified interval. In other words, the command is sent when the
6612 previous frame timestamp was in the given interval, and the
6616 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
6619 @var{TARGET} specifies the target of the command, usually the name of
6620 the filter class or a specific filter instance name.
6622 @var{COMMAND} specifies the name of the command for the target filter.
6624 @var{ARG} is optional and specifies the optional list of argument for
6625 the given @var{COMMAND}.
6627 Between one interval specification and another, whitespaces, or
6628 sequences of characters starting with @code{#} until the end of line,
6629 are ignored and can be used to annotate comments.
6631 A simplified BNF description of the commands specification syntax
6634 @var{COMMAND_FLAG} ::= "enter" | "leave"
6635 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
6636 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
6637 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
6638 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
6639 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
6642 @subsection Examples
6646 Specify audio tempo change at second 4:
6648 asendcmd=c='4.0 atempo tempo 1.5',atempo
6652 Specify a list of drawtext and hue commands in a file.
6654 # show text in the interval 5-10
6655 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
6656 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
6658 # desaturate the image in the interval 15-20
6659 15.0-20.0 [enter] hue reinit s=0,
6660 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
6661 [leave] hue reinit s=1,
6662 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
6664 # apply an exponential saturation fade-out effect, starting from time 25
6665 25 [enter] hue s=exp(t-25)
6668 A filtergraph allowing to read and process the above command list
6669 stored in a file @file{test.cmd}, can be specified with:
6671 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
6676 @section asetpts, setpts
6678 Change the PTS (presentation timestamp) of the input frames.
6680 @code{asetpts} works on audio frames, @code{setpts} on video frames.
6682 This filter accepts the following options:
6687 The expression which is evaluated for each frame to construct its timestamp.
6691 The expression is evaluated through the eval API and can contain the following
6696 frame rate, only defined for constant frame-rate video
6699 the presentation timestamp in input
6702 the count of the input frame, starting from 0.
6704 @item NB_CONSUMED_SAMPLES
6705 the number of consumed samples, not including the current frame (only
6709 the number of samples in the current frame (only audio)
6715 the PTS of the first frame
6718 the time in seconds of the first frame
6721 tell if the current frame is interlaced
6724 the time in seconds of the current frame
6730 original position in the file of the frame, or undefined if undefined
6731 for the current frame
6737 previous input time in seconds
6743 previous output time in seconds
6746 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
6750 wallclock (RTC) time at the start of the movie in microseconds
6753 @subsection Examples
6757 Start counting PTS from zero
6763 Apply fast motion effect:
6769 Apply slow motion effect:
6775 Set fixed rate of 25 frames per second:
6781 Set fixed rate 25 fps with some jitter:
6783 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6787 Apply an offset of 10 seconds to the input PTS:
6793 Generate timestamps from a "live source" and rebase onto the current timebase:
6795 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6801 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6802 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6803 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6804 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6806 The filter also has a video output (see the @var{video} option) with a real
6807 time graph to observe the loudness evolution. The graphic contains the logged
6808 message mentioned above, so it is not printed anymore when this option is set,
6809 unless the verbose logging is set. The main graphing area contains the
6810 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6811 the momentary loudness (400 milliseconds).
6813 More information about the Loudness Recommendation EBU R128 on
6814 @url{http://tech.ebu.ch/loudness}.
6816 The filter accepts the following options:
6821 Activate the video output. The audio stream is passed unchanged whether this
6822 option is set or no. The video stream will be the first output stream if
6823 activated. Default is @code{0}.
6826 Set the video size. This option is for video only. Default and minimum
6827 resolution is @code{640x480}.
6830 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6831 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6832 other integer value between this range is allowed.
6835 Set metadata injection. If set to @code{1}, the audio input will be segmented
6836 into 100ms output frames, each of them containing various loudness information
6837 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
6839 Default is @code{0}.
6842 Force the frame logging level.
6844 Available values are:
6847 information logging level
6849 verbose logging level
6852 By default, the logging level is set to @var{info}. If the @option{video} or
6853 the @option{metadata} options are set, it switches to @var{verbose}.
6856 @subsection Examples
6860 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
6862 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6866 Run an analysis with @command{ffmpeg}:
6868 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6872 @section settb, asettb
6874 Set the timebase to use for the output frames timestamps.
6875 It is mainly useful for testing timebase configuration.
6877 This filter accepts the following options:
6882 The expression which is evaluated into the output timebase.
6886 The value for @option{tb} is an arithmetic expression representing a
6887 rational. The expression can contain the constants "AVTB" (the default
6888 timebase), "intb" (the input timebase) and "sr" (the sample rate,
6889 audio only). Default value is "intb".
6891 @subsection Examples
6895 Set the timebase to 1/25:
6901 Set the timebase to 1/10:
6907 Set the timebase to 1001/1000:
6913 Set the timebase to 2*intb:
6919 Set the default timebase value:
6927 Concatenate audio and video streams, joining them together one after the
6930 The filter works on segments of synchronized video and audio streams. All
6931 segments must have the same number of streams of each type, and that will
6932 also be the number of streams at output.
6934 The filter accepts the following options:
6939 Set the number of segments. Default is 2.
6942 Set the number of output video streams, that is also the number of video
6943 streams in each segment. Default is 1.
6946 Set the number of output audio streams, that is also the number of video
6947 streams in each segment. Default is 0.
6950 Activate unsafe mode: do not fail if segments have a different format.
6954 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
6955 @var{a} audio outputs.
6957 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
6958 segment, in the same order as the outputs, then the inputs for the second
6961 Related streams do not always have exactly the same duration, for various
6962 reasons including codec frame size or sloppy authoring. For that reason,
6963 related synchronized streams (e.g. a video and its audio track) should be
6964 concatenated at once. The concat filter will use the duration of the longest
6965 stream in each segment (except the last one), and if necessary pad shorter
6966 audio streams with silence.
6968 For this filter to work correctly, all segments must start at timestamp 0.
6970 All corresponding streams must have the same parameters in all segments; the
6971 filtering system will automatically select a common pixel format for video
6972 streams, and a common sample format, sample rate and channel layout for
6973 audio streams, but other settings, such as resolution, must be converted
6974 explicitly by the user.
6976 Different frame rates are acceptable but will result in variable frame rate
6977 at output; be sure to configure the output file to handle it.
6979 @subsection Examples
6983 Concatenate an opening, an episode and an ending, all in bilingual version
6984 (video in stream 0, audio in streams 1 and 2):
6986 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
6987 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
6988 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
6989 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
6993 Concatenate two parts, handling audio and video separately, using the
6994 (a)movie sources, and adjusting the resolution:
6996 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
6997 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
6998 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
7000 Note that a desync will happen at the stitch if the audio and video streams
7001 do not have exactly the same duration in the first file.
7005 @section showspectrum
7007 Convert input audio to a video output, representing the audio frequency
7010 The filter accepts the following options:
7014 Specify the video size for the output. Default value is @code{640x512}.
7017 Specify if the spectrum should slide along the window. Default value is
7021 Specify display mode.
7023 It accepts the following values:
7026 all channels are displayed in the same row
7028 all channels are displayed in separate rows
7031 Default value is @samp{combined}.
7034 Specify display color mode.
7036 It accepts the following values:
7039 each channel is displayed in a separate color
7041 each channel is is displayed using the same color scheme
7044 Default value is @samp{channel}.
7047 Specify scale used for calculating intensity color values.
7049 It accepts the following values:
7054 square root, default
7061 Default value is @samp{sqrt}.
7064 Set saturation modifier for displayed colors. Negative values provide
7065 alternative color scheme. @code{0} is no saturation at all.
7066 Saturation must be in [-10.0, 10.0] range.
7067 Default value is @code{1}.
7070 The usage is very similar to the showwaves filter; see the examples in that
7073 @subsection Examples
7077 Large window with logarithmic color scaling:
7079 showspectrum=s=1280x480:scale=log
7083 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
7085 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
7086 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
7092 Convert input audio to a video output, representing the samples waves.
7094 The filter accepts the following named parameters:
7099 Available values are:
7102 Draw a point for each sample.
7105 Draw a vertical line for each sample.
7108 Default value is @code{point}.
7111 Set the number of samples which are printed on the same column. A
7112 larger value will decrease the frame rate. Must be a positive
7113 integer. This option can be set only if the value for @var{rate}
7114 is not explicitly specified.
7117 Set the (approximate) output frame rate. This is done by setting the
7118 option @var{n}. Default value is "25".
7121 Specify the video size for the output. Default value is "600x240".
7124 @subsection Examples
7128 Output the input file audio and the corresponding video representation
7131 amovie=a.mp3,asplit[out0],showwaves[out1]
7135 Create a synthetic signal and show it with showwaves, forcing a
7136 frame rate of 30 frames per second:
7138 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
7142 @c man end MULTIMEDIA FILTERS
7144 @chapter Multimedia Sources
7145 @c man begin MULTIMEDIA SOURCES
7147 Below is a description of the currently available multimedia sources.
7151 This is the same as @ref{movie} source, except it selects an audio
7157 Read audio and/or video stream(s) from a movie container.
7159 This filter accepts the following options:
7163 The name of the resource to read (not necessarily a file but also a device or a
7164 stream accessed through some protocol).
7166 @item format_name, f
7167 Specifies the format assumed for the movie to read, and can be either
7168 the name of a container or an input device. If not specified the
7169 format is guessed from @var{movie_name} or by probing.
7171 @item seek_point, sp
7172 Specifies the seek point in seconds, the frames will be output
7173 starting from this seek point, the parameter is evaluated with
7174 @code{av_strtod} so the numerical value may be suffixed by an IS
7175 postfix. Default value is "0".
7178 Specifies the streams to read. Several streams can be specified,
7179 separated by "+". The source will then have as many outputs, in the
7180 same order. The syntax is explained in the ``Stream specifiers''
7181 section in the ffmpeg manual. Two special names, "dv" and "da" specify
7182 respectively the default (best suited) video and audio stream. Default
7183 is "dv", or "da" if the filter is called as "amovie".
7185 @item stream_index, si
7186 Specifies the index of the video stream to read. If the value is -1,
7187 the best suited video stream will be automatically selected. Default
7188 value is "-1". Deprecated. If the filter is called "amovie", it will select
7189 audio instead of video.
7192 Specifies how many times to read the stream in sequence.
7193 If the value is less than 1, the stream will be read again and again.
7194 Default value is "1".
7196 Note that when the movie is looped the source timestamps are not
7197 changed, so it will generate non monotonically increasing timestamps.
7200 This filter allows to overlay a second video on top of main input of
7201 a filtergraph as shown in this graph:
7203 input -----------> deltapts0 --> overlay --> output
7206 movie --> scale--> deltapts1 -------+
7209 @subsection Examples
7213 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
7214 on top of the input labelled as "in":
7216 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
7217 [in] setpts=PTS-STARTPTS [main];
7218 [main][over] overlay=16:16 [out]
7222 Read from a video4linux2 device, and overlay it on top of the input
7225 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
7226 [in] setpts=PTS-STARTPTS [main];
7227 [main][over] overlay=16:16 [out]
7231 Read the first video stream and the audio stream with id 0x81 from
7232 dvd.vob; the video is connected to the pad named "video" and the audio is
7233 connected to the pad named "audio":
7235 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
7239 @c man end MULTIMEDIA SOURCES