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 This filter accepts the following named options:
3102 Specify whether to extract the top (if the value is @code{0} or
3103 @code{top}) or the bottom field (if the value is @code{1} or
3109 Transform the field order of the input video.
3111 This filter accepts the following options:
3116 Output field order. Valid values are @var{tff} for top field first or @var{bff}
3117 for bottom field first.
3120 Default value is @samp{tff}.
3122 Transformation is achieved by shifting the picture content up or down
3123 by one line, and filling the remaining line with appropriate picture content.
3124 This method is consistent with most broadcast field order converters.
3126 If the input video is not flagged as being interlaced, or it is already
3127 flagged as being of the required output field order then this filter does
3128 not alter the incoming video.
3130 This filter is very useful when converting to or from PAL DV material,
3131 which is bottom field first.
3135 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
3140 Buffer input images and send them when they are requested.
3142 This filter is mainly useful when auto-inserted by the libavfilter
3145 The filter does not take parameters.
3150 Convert the input video to one of the specified pixel formats.
3151 Libavfilter will try to pick one that is supported for the input to
3154 This filter accepts the following parameters:
3158 A '|'-separated list of pixel format names, for example
3159 "pix_fmts=yuv420p|monow|rgb24".
3163 @subsection Examples
3167 Convert the input video to the format @var{yuv420p}
3169 format=pix_fmts=yuv420p
3172 Convert the input video to any of the formats in the list
3174 format=pix_fmts=yuv420p|yuv444p|yuv410p
3180 Convert the video to specified constant frame rate by duplicating or dropping
3181 frames as necessary.
3183 This filter accepts the following named parameters:
3187 Desired output frame rate. The default is @code{25}.
3192 Possible values are:
3195 zero round towards 0
3199 round towards -infinity
3201 round towards +infinity
3205 The default is @code{near}.
3209 Alternatively, the options can be specified as a flat string:
3210 @var{fps}[:@var{round}].
3212 See also the @ref{setpts} filter.
3216 Select one frame every N-th frame.
3218 This filter accepts the following option:
3221 Select frame after every @code{step} frames.
3222 Allowed values are positive integers higher than 0. Default value is @code{1}.
3228 Apply a frei0r effect to the input video.
3230 To enable compilation of this filter you need to install the frei0r
3231 header and configure FFmpeg with @code{--enable-frei0r}.
3233 This filter accepts the following options:
3238 The name to the frei0r effect to load. If the environment variable
3239 @env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
3240 directories specified by the colon separated list in @env{FREIOR_PATH},
3241 otherwise in the standard frei0r paths, which are in this order:
3242 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
3243 @file{/usr/lib/frei0r-1/}.
3246 A '|'-separated list of parameters to pass to the frei0r effect.
3250 A frei0r effect parameter can be a boolean (whose values are specified
3251 with "y" and "n"), a double, a color (specified by the syntax
3252 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
3253 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
3254 description), a position (specified by the syntax @var{X}/@var{Y},
3255 @var{X} and @var{Y} being float numbers) and a string.
3257 The number and kind of parameters depend on the loaded effect. If an
3258 effect parameter is not specified the default value is set.
3260 @subsection Examples
3264 Apply the distort0r effect, set the first two double parameters:
3266 frei0r=filter_name=distort0r:filter_params=0.5|0.01
3270 Apply the colordistance effect, take a color as first parameter:
3272 frei0r=colordistance:0.2/0.3/0.4
3273 frei0r=colordistance:violet
3274 frei0r=colordistance:0x112233
3278 Apply the perspective effect, specify the top left and top right image
3281 frei0r=perspective:0.2/0.2|0.8/0.2
3285 For more information see:
3286 @url{http://frei0r.dyne.org}
3290 The filter accepts the following options:
3294 the luminance expression
3296 the chrominance blue expression
3298 the chrominance red expression
3300 the alpha expression
3303 If one of the chrominance expression is not defined, it falls back on the other
3304 one. If no alpha expression is specified it will evaluate to opaque value.
3305 If none of chrominance expressions are
3306 specified, they will evaluate the luminance expression.
3308 The expressions can use the following variables and functions:
3312 The sequential number of the filtered frame, starting from @code{0}.
3316 The coordinates of the current sample.
3320 The width and height of the image.
3324 Width and height scale depending on the currently filtered plane. It is the
3325 ratio between the corresponding luma plane number of pixels and the current
3326 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
3327 @code{0.5,0.5} for chroma planes.
3330 Time of the current frame, expressed in seconds.
3333 Return the value of the pixel at location (@var{x},@var{y}) of the current
3337 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
3341 Return the value of the pixel at location (@var{x},@var{y}) of the
3342 blue-difference chroma plane. Returns 0 if there is no such plane.
3345 Return the value of the pixel at location (@var{x},@var{y}) of the
3346 red-difference chroma plane. Returns 0 if there is no such plane.
3349 Return the value of the pixel at location (@var{x},@var{y}) of the alpha
3350 plane. Returns 0 if there is no such plane.
3353 For functions, if @var{x} and @var{y} are outside the area, the value will be
3354 automatically clipped to the closer edge.
3356 @subsection Examples
3360 Flip the image horizontally:
3366 Generate a bidimensional sine wave, with angle @code{PI/3} and a
3367 wavelength of 100 pixels:
3369 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
3373 Generate a fancy enigmatic moving light:
3375 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
3381 Fix the banding artifacts that are sometimes introduced into nearly flat
3382 regions by truncation to 8bit color depth.
3383 Interpolate the gradients that should go where the bands are, and
3386 This filter is designed for playback only. Do not use it prior to
3387 lossy compression, because compression tends to lose the dither and
3388 bring back the bands.
3390 This filter accepts the following options:
3395 The maximum amount by which the filter will change any one pixel. Also the
3396 threshold for detecting nearly flat regions. Acceptable values range from .51 to
3397 64, default value is 1.2, out-of-range values will be clipped to the valid
3401 The neighborhood to fit the gradient to. A larger radius makes for smoother
3402 gradients, but also prevents the filter from modifying the pixels near detailed
3403 regions. Acceptable values are 8-32, default value is 16, out-of-range values
3404 will be clipped to the valid range.
3408 Alternatively, the options can be specified as a flat string:
3409 @var{strength}[:@var{radius}]
3411 @subsection Examples
3415 Apply the filter with a @code{3.5} strength and radius of @code{8}:
3421 Specify radius, omitting the strength (which will fall-back to the default
3431 Flip the input video horizontally.
3433 For example to horizontally flip the input video with @command{ffmpeg}:
3435 ffmpeg -i in.avi -vf "hflip" out.avi
3439 This filter applies a global color histogram equalization on a
3442 It can be used to correct video that has a compressed range of pixel
3443 intensities. The filter redistributes the pixel intensities to
3444 equalize their distribution across the intensity range. It may be
3445 viewed as an "automatically adjusting contrast filter". This filter is
3446 useful only for correcting degraded or poorly captured source
3449 The filter accepts the following options:
3453 Determine the amount of equalization to be applied. As the strength
3454 is reduced, the distribution of pixel intensities more-and-more
3455 approaches that of the input frame. The value must be a float number
3456 in the range [0,1] and defaults to 0.200.
3459 Set the maximum intensity that can generated and scale the output
3460 values appropriately. The strength should be set as desired and then
3461 the intensity can be limited if needed to avoid washing-out. The value
3462 must be a float number in the range [0,1] and defaults to 0.210.
3465 Set the antibanding level. If enabled the filter will randomly vary
3466 the luminance of output pixels by a small amount to avoid banding of
3467 the histogram. Possible values are @code{none}, @code{weak} or
3468 @code{strong}. It defaults to @code{none}.
3473 Compute and draw a color distribution histogram for the input video.
3475 The computed histogram is a representation of distribution of color components
3478 The filter accepts the following options:
3484 It accepts the following values:
3487 standard histogram that display color components distribution in an image.
3488 Displays color graph for each color component. Shows distribution
3489 of the Y, U, V, A or G, B, R components, depending on input format,
3490 in current frame. Bellow each graph is color component scale meter.
3493 chroma values in vectorscope, if brighter more such chroma values are
3494 distributed in an image.
3495 Displays chroma values (U/V color placement) in two dimensional graph
3496 (which is called a vectorscope). It can be used to read of the hue and
3497 saturation of the current frame. At a same time it is a histogram.
3498 The whiter a pixel in the vectorscope, the more pixels of the input frame
3499 correspond to that pixel (that is the more pixels have this chroma value).
3500 The V component is displayed on the horizontal (X) axis, with the leftmost
3501 side being V = 0 and the rightmost side being V = 255.
3502 The U component is displayed on the vertical (Y) axis, with the top
3503 representing U = 0 and the bottom representing U = 255.
3505 The position of a white pixel in the graph corresponds to the chroma value
3506 of a pixel of the input clip. So the graph can be used to read of the
3507 hue (color flavor) and the saturation (the dominance of the hue in the color).
3508 As the hue of a color changes, it moves around the square. At the center of
3509 the square, the saturation is zero, which means that the corresponding pixel
3510 has no color. If you increase the amount of a specific color, while leaving
3511 the other colors unchanged, the saturation increases, and you move towards
3512 the edge of the square.
3515 chroma values in vectorscope, similar as @code{color} but actual chroma values
3519 per row/column color component graph. In row mode graph in the left side represents
3520 color component value 0 and right side represents value = 255. In column mode top
3521 side represents color component value = 0 and bottom side represents value = 255.
3523 Default value is @code{levels}.
3526 Set height of level in @code{levels}. Default value is @code{200}.
3527 Allowed range is [50, 2048].
3530 Set height of color scale in @code{levels}. Default value is @code{12}.
3531 Allowed range is [0, 40].
3534 Set step for @code{waveform} mode. Smaller values are useful to find out how much
3535 of same luminance values across input rows/columns are distributed.
3536 Default value is @code{10}. Allowed range is [1, 255].
3539 Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
3540 Default is @code{row}.
3543 Set display mode for @code{waveform} and @code{levels}.
3544 It accepts the following values:
3547 Display separate graph for the color components side by side in
3548 @code{row} waveform mode or one below other in @code{column} waveform mode
3549 for @code{waveform} histogram mode. For @code{levels} histogram mode
3550 per color component graphs are placed one bellow other.
3552 This display mode in @code{waveform} histogram mode makes it easy to spot
3553 color casts in the highlights and shadows of an image, by comparing the
3554 contours of the top and the bottom of each waveform.
3555 Since whites, grays, and blacks are characterized by
3556 exactly equal amounts of red, green, and blue, neutral areas of the
3557 picture should display three waveforms of roughly equal width/height.
3558 If not, the correction is easy to make by making adjustments to level the
3562 Presents information that's identical to that in the @code{parade}, except
3563 that the graphs representing color components are superimposed directly
3566 This display mode in @code{waveform} histogram mode can make it easier to spot
3567 the relative differences or similarities in overlapping areas of the color
3568 components that are supposed to be identical, such as neutral whites, grays,
3571 Default is @code{parade}.
3574 @subsection Examples
3579 Calculate and draw histogram:
3581 ffplay -i input -vf histogram
3588 High precision/quality 3d denoise filter. This filter aims to reduce
3589 image noise producing smooth images and making still images really
3590 still. It should enhance compressibility.
3592 It accepts the following optional parameters:
3596 a non-negative float number which specifies spatial luma strength,
3599 @item chroma_spatial
3600 a non-negative float number which specifies spatial chroma strength,
3601 defaults to 3.0*@var{luma_spatial}/4.0
3604 a float number which specifies luma temporal strength, defaults to
3605 6.0*@var{luma_spatial}/4.0
3608 a float number which specifies chroma temporal strength, defaults to
3609 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
3614 Modify the hue and/or the saturation of the input.
3616 This filter accepts the following optional named options:
3620 Specify the hue angle as a number of degrees. It accepts a float
3621 number or an expression, and defaults to 0.0.
3624 Specify the hue angle as a number of radians. It accepts a float
3625 number or an expression, and defaults to 0.0.
3628 Specify the saturation in the [-10,10] range. It accepts a float number and
3632 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
3633 following constants:
3637 frame count of the input frame starting from 0
3640 presentation timestamp of the input frame expressed in time base units
3643 frame rate of the input video, NAN if the input frame rate is unknown
3646 timestamp expressed in seconds, NAN if the input timestamp is unknown
3649 time base of the input video
3652 The options can also be set using the syntax: @var{hue}:@var{saturation}
3654 In this case @var{hue} is expressed in degrees.
3656 @subsection Examples
3660 Set the hue to 90 degrees and the saturation to 1.0:
3666 Same command but expressing the hue in radians:
3672 Same command without named options, hue must be expressed in degrees:
3678 Note that "h:s" syntax does not support expressions for the values of
3679 h and s, so the following example will issue an error:
3685 Rotate hue and make the saturation swing between 0
3686 and 2 over a period of 1 second:
3688 hue="H=2*PI*t: s=sin(2*PI*t)+1"
3692 Apply a 3 seconds saturation fade-in effect starting at 0:
3697 The general fade-in expression can be written as:
3699 hue="s=min(0\, max((t-START)/DURATION\, 1))"
3703 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
3705 hue="s=max(0\, min(1\, (8-t)/3))"
3708 The general fade-out expression can be written as:
3710 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
3715 @subsection Commands
3717 This filter supports the following command:
3720 Modify the hue and/or the saturation of the input video.
3721 The command accepts the same named options and syntax than when calling the
3722 filter from the command-line.
3724 If a parameter is omitted, it is kept at its current value.
3729 Detect video interlacing type.
3731 This filter tries to detect if the input is interlaced or progressive,
3732 top or bottom field first.
3734 The filter accepts the following options:
3738 Set interlacing threshold.
3740 Set progressive threshold.
3745 Deinterleave or interleave fields.
3747 This filter allows to process interlaced images fields without
3748 deinterlacing them. Deinterleaving splits the input frame into 2
3749 fields (so called half pictures). Odd lines are moved to the top
3750 half of the output image, even lines to the bottom half.
3751 You can process (filter) them independently and then re-interleave them.
3753 The filter accepts the following options:
3757 @item chroma_mode, s
3759 Available values for @var{luma_mode}, @var{chroma_mode} and
3760 @var{alpha_mode} are:
3766 @item deinterleave, d
3767 Deinterleave fields, placing one above the other.
3770 Interleave fields. Reverse the effect of deinterleaving.
3772 Default value is @code{none}.
3775 @item chroma_swap, cs
3776 @item alpha_swap, as
3777 Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}.
3782 Deinterlace input video by applying Donald Graft's adaptive kernel
3783 deinterling. Work on interlaced parts of a video to produce
3786 The description of the accepted parameters follows.
3790 Set the threshold which affects the filter's tolerance when
3791 determining if a pixel line must be processed. It must be an integer
3792 in the range [0,255] and defaults to 10. A value of 0 will result in
3793 applying the process on every pixels.
3796 Paint pixels exceeding the threshold value to white if set to 1.
3800 Set the fields order. Swap fields if set to 1, leave fields alone if
3804 Enable additional sharpening if set to 1. Default is 0.
3807 Enable twoway sharpening if set to 1. Default is 0.
3810 @subsection Examples
3814 Apply default values:
3816 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
3820 Enable additional sharpening:
3826 Paint processed pixels in white:
3832 @section lut, lutrgb, lutyuv
3834 Compute a look-up table for binding each pixel component input value
3835 to an output value, and apply it to input video.
3837 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3838 to an RGB input video.
3840 These filters accept the following options:
3843 set first pixel component expression
3845 set second pixel component expression
3847 set third pixel component expression
3849 set fourth pixel component expression, corresponds to the alpha component
3852 set red component expression
3854 set green component expression
3856 set blue component expression
3858 alpha component expression
3861 set Y/luminance component expression
3863 set U/Cb component expression
3865 set V/Cr component expression
3868 Each of them specifies the expression to use for computing the lookup table for
3869 the corresponding pixel component values.
3871 The exact component associated to each of the @var{c*} options depends on the
3874 The @var{lut} filter requires either YUV or RGB pixel formats in input,
3875 @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
3877 The expressions can contain the following constants and functions:
3881 the input width and height
3884 input value for the pixel component
3887 the input value clipped in the @var{minval}-@var{maxval} range
3890 maximum value for the pixel component
3893 minimum value for the pixel component
3896 the negated value for the pixel component value clipped in the
3897 @var{minval}-@var{maxval} range , it corresponds to the expression
3898 "maxval-clipval+minval"
3901 the computed value in @var{val} clipped in the
3902 @var{minval}-@var{maxval} range
3904 @item gammaval(gamma)
3905 the computed gamma correction value of the pixel component value
3906 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3908 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3912 All expressions default to "val".
3914 @subsection Examples
3920 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3921 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3924 The above is the same as:
3926 lutrgb="r=negval:g=negval:b=negval"
3927 lutyuv="y=negval:u=negval:v=negval"
3937 Remove chroma components, turns the video into a graytone image:
3939 lutyuv="u=128:v=128"
3943 Apply a luma burning effect:
3949 Remove green and blue components:
3955 Set a constant alpha channel value on input:
3957 format=rgba,lutrgb=a="maxval-minval/2"
3961 Correct luminance gamma by a 0.5 factor:
3963 lutyuv=y=gammaval(0.5)
3967 Discard least significant bits of luma:
3969 lutyuv=y='bitand(val, 128+64+32)'
3975 Apply an MPlayer filter to the input video.
3977 This filter provides a wrapper around most of the filters of
3980 This wrapper is considered experimental. Some of the wrapped filters
3981 may not work properly and we may drop support for them, as they will
3982 be implemented natively into FFmpeg. Thus you should avoid
3983 depending on them when writing portable scripts.
3985 The filters accepts the parameters:
3986 @var{filter_name}[:=]@var{filter_params}
3988 @var{filter_name} is the name of a supported MPlayer filter,
3989 @var{filter_params} is a string containing the parameters accepted by
3992 The list of the currently supported filters follows:
4019 The parameter syntax and behavior for the listed filters are the same
4020 of the corresponding MPlayer filters. For detailed instructions check
4021 the "VIDEO FILTERS" section in the MPlayer manual.
4023 @subsection Examples
4027 Adjust gamma, brightness, contrast:
4033 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
4039 This filter accepts an integer in input, if non-zero it negates the
4040 alpha component (if available). The default value in input is 0.
4044 Force libavfilter not to use any of the specified pixel formats for the
4045 input to the next filter.
4047 This filter accepts the following parameters:
4051 A '|'-separated list of pixel format names, for example
4052 "pix_fmts=yuv420p|monow|rgb24".
4056 @subsection Examples
4060 Force libavfilter to use a format different from @var{yuv420p} for the
4061 input to the vflip filter:
4063 noformat=pix_fmts=yuv420p,vflip
4067 Convert the input video to any of the formats not contained in the list:
4069 noformat=yuv420p|yuv444p|yuv410p
4075 Add noise on video input frame.
4077 The filter accepts the following options:
4085 Set noise seed for specific pixel component or all pixel components in case
4086 of @var{all_seed}. Default value is @code{123457}.
4088 @item all_strength, alls
4089 @item c0_strength, c0s
4090 @item c1_strength, c1s
4091 @item c2_strength, c2s
4092 @item c3_strength, c3s
4093 Set noise strength for specific pixel component or all pixel components in case
4094 @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100].
4096 @item all_flags, allf
4101 Set pixel component flags or set flags for all components if @var{all_flags}.
4102 Available values for component flags are:
4105 averaged temporal noise (smoother)
4107 mix random noise with a (semi)regular pattern
4109 higher quality (slightly better looking, slightly slower)
4111 temporal noise (noise pattern changes between frames)
4113 uniform noise (gaussian otherwise)
4117 @subsection Examples
4119 Add temporal and uniform noise to input video:
4121 noise=alls=20:allf=t+u
4126 Pass the video source unchanged to the output.
4130 Apply video transform using libopencv.
4132 To enable this filter install libopencv library and headers and
4133 configure FFmpeg with @code{--enable-libopencv}.
4135 This filter accepts the following parameters:
4140 The name of the libopencv filter to apply.
4143 The parameters to pass to the libopencv filter. If not specified the default
4148 Refer to the official libopencv documentation for more precise
4150 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
4152 Follows the list of supported libopencv filters.
4157 Dilate an image by using a specific structuring element.
4158 This filter corresponds to the libopencv function @code{cvDilate}.
4160 It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
4162 @var{struct_el} represents a structuring element, and has the syntax:
4163 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
4165 @var{cols} and @var{rows} represent the number of columns and rows of
4166 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
4167 point, and @var{shape} the shape for the structuring element, and
4168 can be one of the values "rect", "cross", "ellipse", "custom".
4170 If the value for @var{shape} is "custom", it must be followed by a
4171 string of the form "=@var{filename}". The file with name
4172 @var{filename} is assumed to represent a binary image, with each
4173 printable character corresponding to a bright pixel. When a custom
4174 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
4175 or columns and rows of the read file are assumed instead.
4177 The default value for @var{struct_el} is "3x3+0x0/rect".
4179 @var{nb_iterations} specifies the number of times the transform is
4180 applied to the image, and defaults to 1.
4182 Follow some example:
4184 # use the default values
4187 # dilate using a structuring element with a 5x5 cross, iterate two times
4188 ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
4190 # read the shape from the file diamond.shape, iterate two times
4191 # the file diamond.shape may contain a pattern of characters like this:
4197 # the specified cols and rows are ignored (but not the anchor point coordinates)
4198 ocv=dilate:0x0+2x2/custom=diamond.shape|2
4203 Erode an image by using a specific structuring element.
4204 This filter corresponds to the libopencv function @code{cvErode}.
4206 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4207 with the same syntax and semantics as the @ref{dilate} filter.
4211 Smooth the input video.
4213 The filter takes the following parameters:
4214 @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
4216 @var{type} is the type of smooth filter to apply, and can be one of
4217 the following values: "blur", "blur_no_scale", "median", "gaussian",
4218 "bilateral". The default value is "gaussian".
4220 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
4221 parameters whose meanings depend on smooth type. @var{param1} and
4222 @var{param2} accept integer positive values or 0, @var{param3} and
4223 @var{param4} accept float values.
4225 The default value for @var{param1} is 3, the default value for the
4226 other parameters is 0.
4228 These parameters correspond to the parameters assigned to the
4229 libopencv function @code{cvSmooth}.
4234 Overlay one video on top of another.
4236 It takes two inputs and one output, the first input is the "main"
4237 video on which the second input is overlayed.
4239 This filter accepts the following parameters:
4241 A description of the accepted options follows.
4246 Set the expression for the x and y coordinates of the overlayed video
4247 on the main video. Default value is "0" for both expressions. In case
4248 the expression is invalid, it is set to a huge value (meaning that the
4249 overlay will not be displayed within the output visible area).
4252 Set the expression which enables the overlay. If the evaluation is
4253 different from 0, the overlay is displayed on top of the input
4254 frame. By default it is "1".
4257 Set when the expressions for @option{x}, @option{y}, and
4258 @option{enable} are evaluated.
4260 It accepts the following values:
4263 only evaluate expressions once during the filter initialization or
4264 when a command is processed
4267 evaluate expressions for each incoming frame
4270 Default value is @samp{frame}.
4273 If set to 1, force the output to terminate when the shortest input
4274 terminates. Default value is 0.
4277 Set the format for the output video.
4279 It accepts the following values:
4291 Default value is @samp{yuv420}.
4293 @item rgb @emph{(deprecated)}
4294 If set to 1, force the filter to accept inputs in the RGB
4295 color space. Default value is 0. This option is deprecated, use
4296 @option{format} instead.
4299 The @option{x}, @option{y}, and @option{enable} expressions can
4300 contain the following parameters.
4305 main input width and height
4309 overlay input width and height
4313 the computed values for @var{x} and @var{y}. They are evaluated for
4318 horizontal and vertical chroma subsample values of the output
4319 format. For example for the pixel format "yuv422p" @var{hsub} is 2 and
4323 the number of input frame, starting from 0
4326 the position in the file of the input frame, NAN if unknown
4329 timestamp expressed in seconds, NAN if the input timestamp is unknown
4332 Note that the @var{n}, @var{pos}, @var{t} variables are available only
4333 when evaluation is done @emph{per frame}, and will evaluate to NAN
4334 when @option{eval} is set to @samp{init}.
4336 Be aware that frames are taken from each input video in timestamp
4337 order, hence, if their initial timestamps differ, it is a a good idea
4338 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
4339 have them begin in the same zero timestamp, as it does the example for
4340 the @var{movie} filter.
4342 You can chain together more overlays but you should test the
4343 efficiency of such approach.
4345 @subsection Commands
4347 This filter supports the following command:
4350 Set the @option{x} option expression.
4353 Set the @option{y} option expression.
4356 Set the @option{enable} option expression.
4359 @subsection Examples
4363 Draw the overlay at 10 pixels from the bottom right corner of the main
4366 overlay=main_w-overlay_w-10:main_h-overlay_h-10
4369 Using named options the example above becomes:
4371 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
4375 Insert a transparent PNG logo in the bottom left corner of the input,
4376 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
4378 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
4382 Insert 2 different transparent PNG logos (second logo on bottom
4383 right corner) using the @command{ffmpeg} tool:
4385 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
4389 Add a transparent color layer on top of the main video, @code{WxH}
4390 must specify the size of the main input to the overlay filter:
4392 color=color=red@@.3:size=WxH [over]; [in][over] overlay [out]
4396 Play an original video and a filtered version (here with the deshake
4397 filter) side by side using the @command{ffplay} tool:
4399 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
4402 The above command is the same as:
4404 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
4408 Make a sliding overlay appearing from the left to the right top part of the
4409 screen starting since time 2:
4411 overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
4415 Compose output by putting two input videos side to side:
4417 ffmpeg -i left.avi -i right.avi -filter_complex "
4418 nullsrc=size=200x100 [background];
4419 [0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
4420 [1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
4421 [background][left] overlay=shortest=1 [background+left];
4422 [background+left][right] overlay=shortest=1:x=100 [left+right]
4427 Chain several overlays in cascade:
4429 nullsrc=s=200x200 [bg];
4430 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
4431 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
4432 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
4433 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
4434 [in3] null, [mid2] overlay=100:100 [out0]
4441 Add paddings to the input image, and place the original input at the
4442 given coordinates @var{x}, @var{y}.
4444 This filter accepts the following parameters:
4449 Specify an expression for the size of the output image with the
4450 paddings added. If the value for @var{width} or @var{height} is 0, the
4451 corresponding input size is used for the output.
4453 The @var{width} expression can reference the value set by the
4454 @var{height} expression, and vice versa.
4456 The default value of @var{width} and @var{height} is 0.
4460 Specify an expression for the offsets where to place the input image
4461 in the padded area with respect to the top/left border of the output
4464 The @var{x} expression can reference the value set by the @var{y}
4465 expression, and vice versa.
4467 The default value of @var{x} and @var{y} is 0.
4470 Specify the color of the padded area, it can be the name of a color
4471 (case insensitive match) or a 0xRRGGBB[AA] sequence.
4473 The default value of @var{color} is "black".
4476 The value for the @var{width}, @var{height}, @var{x}, and @var{y}
4477 options are expressions containing the following constants:
4481 the input video width and height
4484 same as @var{in_w} and @var{in_h}
4487 the output width and height, that is the size of the padded area as
4488 specified by the @var{width} and @var{height} expressions
4491 same as @var{out_w} and @var{out_h}
4494 x and y offsets as specified by the @var{x} and @var{y}
4495 expressions, or NAN if not yet specified
4498 same as @var{iw} / @var{ih}
4501 input sample aspect ratio
4504 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4507 horizontal and vertical chroma subsample values. For example for the
4508 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4511 @subsection Examples
4515 Add paddings with color "violet" to the input video. Output video
4516 size is 640x480, the top-left corner of the input video is placed at
4519 pad=640:480:0:40:violet
4522 The example above is equivalent to the following command:
4524 pad=width=640:height=480:x=0:y=40:color=violet
4528 Pad the input to get an output with dimensions increased by 3/2,
4529 and put the input video at the center of the padded area:
4531 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
4535 Pad the input to get a squared output with size equal to the maximum
4536 value between the input width and height, and put the input video at
4537 the center of the padded area:
4539 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
4543 Pad the input to get a final w/h ratio of 16:9:
4545 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
4549 In case of anamorphic video, in order to set the output display aspect
4550 correctly, it is necessary to use @var{sar} in the expression,
4551 according to the relation:
4553 (ih * X / ih) * sar = output_dar
4554 X = output_dar / sar
4557 Thus the previous example needs to be modified to:
4559 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
4563 Double output size and put the input video in the bottom-right
4564 corner of the output padded area:
4566 pad="2*iw:2*ih:ow-iw:oh-ih"
4570 @section pixdesctest
4572 Pixel format descriptor test filter, mainly useful for internal
4573 testing. The output video should be equal to the input video.
4577 format=monow, pixdesctest
4580 can be used to test the monowhite pixel format descriptor definition.
4584 Enable the specified chain of postprocessing subfilters using libpostproc. This
4585 library should be automatically selected with a GPL build (@code{--enable-gpl}).
4586 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
4587 Each subfilter and some options have a short and a long name that can be used
4588 interchangeably, i.e. dr/dering are the same.
4590 The filters accept the following options:
4594 Set postprocessing subfilters string.
4597 All subfilters share common options to determine their scope:
4601 Honor the quality commands for this subfilter.
4604 Do chrominance filtering, too (default).
4607 Do luminance filtering only (no chrominance).
4610 Do chrominance filtering only (no luminance).
4613 These options can be appended after the subfilter name, separated by a '|'.
4615 Available subfilters are:
4618 @item hb/hdeblock[|difference[|flatness]]
4619 Horizontal deblocking filter
4622 Difference factor where higher values mean more deblocking (default: @code{32}).
4624 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4627 @item vb/vdeblock[|difference[|flatness]]
4628 Vertical deblocking filter
4631 Difference factor where higher values mean more deblocking (default: @code{32}).
4633 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4636 @item ha/hadeblock[|difference[|flatness]]
4637 Accurate horizontal deblocking filter
4640 Difference factor where higher values mean more deblocking (default: @code{32}).
4642 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4645 @item va/vadeblock[|difference[|flatness]]
4646 Accurate vertical deblocking filter
4649 Difference factor where higher values mean more deblocking (default: @code{32}).
4651 Flatness threshold where lower values mean more deblocking (default: @code{39}).
4655 The horizontal and vertical deblocking filters share the difference and
4656 flatness values so you cannot set different horizontal and vertical
4661 Experimental horizontal deblocking filter
4664 Experimental vertical deblocking filter
4669 @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
4672 larger -> stronger filtering
4674 larger -> stronger filtering
4676 larger -> stronger filtering
4679 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
4682 Stretch luminance to @code{0-255}.
4685 @item lb/linblenddeint
4686 Linear blend deinterlacing filter that deinterlaces the given block by
4687 filtering all lines with a @code{(1 2 1)} filter.
4689 @item li/linipoldeint
4690 Linear interpolating deinterlacing filter that deinterlaces the given block by
4691 linearly interpolating every second line.
4693 @item ci/cubicipoldeint
4694 Cubic interpolating deinterlacing filter deinterlaces the given block by
4695 cubically interpolating every second line.
4697 @item md/mediandeint
4698 Median deinterlacing filter that deinterlaces the given block by applying a
4699 median filter to every second line.
4701 @item fd/ffmpegdeint
4702 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
4703 second line with a @code{(-1 4 2 4 -1)} filter.
4706 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
4707 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
4709 @item fq/forceQuant[|quantizer]
4710 Overrides the quantizer table from the input with the constant quantizer you
4718 Default pp filter combination (@code{hb|a,vb|a,dr|a})
4721 Fast pp filter combination (@code{h1|a,v1|a,dr|a})
4724 High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a})
4727 @subsection Examples
4731 Apply horizontal and vertical deblocking, deringing and automatic
4732 brightness/contrast:
4738 Apply default filters without brightness/contrast correction:
4744 Apply default filters and temporal denoiser:
4746 pp=default/tmpnoise|1|2|3
4750 Apply deblocking on luminance only, and switch vertical deblocking on or off
4751 automatically depending on available CPU time:
4759 Suppress a TV station logo, using an image file to determine which
4760 pixels comprise the logo. It works by filling in the pixels that
4761 comprise the logo with neighboring pixels.
4763 This filter requires one argument which specifies the filter bitmap
4764 file, which can be any image format supported by libavformat. The
4765 width and height of the image file must match those of the video
4766 stream being processed.
4768 Pixels in the provided bitmap image with a value of zero are not
4769 considered part of the logo, non-zero pixels are considered part of
4770 the logo. If you use white (255) for the logo and black (0) for the
4771 rest, you will be safe. For making the filter bitmap, it is
4772 recommended to take a screen capture of a black frame with the logo
4773 visible, and then using a threshold filter followed by the erode
4774 filter once or twice.
4776 If needed, little splotches can be fixed manually. Remember that if
4777 logo pixels are not covered, the filter quality will be much
4778 reduced. Marking too many pixels as part of the logo does not hurt as
4779 much, but it will increase the amount of blurring needed to cover over
4780 the image and will destroy more information than necessary, and extra
4781 pixels will slow things down on a large logo.
4785 Scale (resize) the input video, using the libswscale library.
4787 The scale filter forces the output display aspect ratio to be the same
4788 of the input, by changing the output sample aspect ratio.
4790 This filter accepts a list of named options in the form of
4791 @var{key}=@var{value} pairs separated by ":". If the key for the first
4792 two options is not specified, the assumed keys for the first two
4793 values are @code{w} and @code{h}. If the first option has no key and
4794 can be interpreted like a video size specification, it will be used
4795 to set the video size.
4797 A description of the accepted options follows.
4802 default value is @code{iw}. See below
4803 for the list of accepted constants.
4806 Output video height.
4807 default value is @code{ih}.
4808 See below for the list of accepted constants.
4811 Set the interlacing. It accepts the following values:
4815 force interlaced aware scaling
4818 do not apply interlaced scaling
4821 select interlaced aware scaling depending on whether the source frames
4822 are flagged as interlaced or not
4825 Default value is @code{0}.
4828 Set libswscale scaling flags. If not explictly specified the filter
4829 applies a bilinear scaling algorithm.
4832 Set the video size, the value must be a valid abbreviation or in the
4833 form @var{width}x@var{height}.
4836 The values of the @var{w} and @var{h} options are expressions
4837 containing the following constants:
4841 the input width and height
4844 same as @var{in_w} and @var{in_h}
4847 the output (cropped) width and height
4850 same as @var{out_w} and @var{out_h}
4853 same as @var{iw} / @var{ih}
4856 input sample aspect ratio
4859 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
4862 horizontal and vertical chroma subsample values. For example for the
4863 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
4866 If the input image format is different from the format requested by
4867 the next filter, the scale filter will convert the input to the
4870 If the value for @var{w} or @var{h} is 0, the respective input
4871 size is used for the output.
4873 If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
4874 respective output size, a value that maintains the aspect ratio of the input
4877 @subsection Examples
4881 Scale the input video to a size of 200x100:
4886 This is equivalent to:
4897 Specify a size abbreviation for the output size:
4902 which can also be written as:
4908 Scale the input to 2x:
4914 The above is the same as:
4920 Scale the input to 2x with forced interlaced scaling:
4922 scale=2*iw:2*ih:interl=1
4926 Scale the input to half size:
4932 Increase the width, and set the height to the same size:
4938 Seek for Greek harmony:
4945 Increase the height, and set the width to 3/2 of the height:
4947 scale=w=3/2*oh:h=3/5*ih
4951 Increase the size, but make the size a multiple of the chroma
4954 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
4958 Increase the width to a maximum of 500 pixels, keep the same input
4961 scale=w='min(500\, iw*3/2):h=-1'
4965 @section separatefields
4967 The @code{separatefields} takes a frame-based video input and splits
4968 each frame into its components fields, producing a new half height clip
4969 with twice the frame rate and twice the frame count.
4971 This filter use field-dominance information in frame to decide which
4972 of each pair of fields to place first in the output.
4973 If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
4975 @section setdar, setsar
4977 The @code{setdar} filter sets the Display Aspect Ratio for the filter
4980 This is done by changing the specified Sample (aka Pixel) Aspect
4981 Ratio, according to the following equation:
4983 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
4986 Keep in mind that the @code{setdar} filter does not modify the pixel
4987 dimensions of the video frame. Also the display aspect ratio set by
4988 this filter may be changed by later filters in the filterchain,
4989 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
4992 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
4993 the filter output video.
4995 Note that as a consequence of the application of this filter, the
4996 output display aspect ratio will change according to the equation
4999 Keep in mind that the sample aspect ratio set by the @code{setsar}
5000 filter may be changed by later filters in the filterchain, e.g. if
5001 another "setsar" or a "setdar" filter is applied.
5003 The @code{setdar} and @code{setsar} filters accept a string in the
5004 form @var{num}:@var{den} expressing an aspect ratio, or the following
5005 named options, expressed as a sequence of @var{key}=@var{value} pairs,
5010 Set the maximum integer value to use for expressing numerator and
5011 denominator when reducing the expressed aspect ratio to a rational.
5012 Default value is @code{100}.
5014 @item r, ratio, dar, sar:
5015 Set the aspect ratio used by the filter.
5017 The parameter can be a floating point number string, an expression, or
5018 a string of the form @var{num}:@var{den}, where @var{num} and
5019 @var{den} are the numerator and denominator of the aspect ratio. If
5020 the parameter is not specified, it is assumed the value "0".
5021 In case the form "@var{num}:@var{den}" the @code{:} character should
5025 If the keys are omitted in the named options list, the specifed values
5026 are assumed to be @var{ratio} and @var{max} in that order.
5028 For example to change the display aspect ratio to 16:9, specify:
5031 # the above is equivalent to
5037 To change the sample aspect ratio to 10:11, specify:
5040 # the above is equivalent to
5044 To set a display aspect ratio of 16:9, and specify a maximum integer value of
5045 1000 in the aspect ratio reduction, use the command:
5047 setdar=ratio='16:9':max=1000
5053 Force field for the output video frame.
5055 The @code{setfield} filter marks the interlace type field for the
5056 output frames. It does not change the input frame, but only sets the
5057 corresponding property, which affects how the frame is treated by
5058 following filters (e.g. @code{fieldorder} or @code{yadif}).
5060 The filter accepts the following options:
5065 Available values are:
5069 Keep the same field property.
5072 Mark the frame as bottom-field-first.
5075 Mark the frame as top-field-first.
5078 Mark the frame as progressive.
5084 Show a line containing various information for each input video frame.
5085 The input video is not modified.
5087 The shown line contains a sequence of key/value pairs of the form
5088 @var{key}:@var{value}.
5090 A description of each shown parameter follows:
5094 sequential number of the input frame, starting from 0
5097 Presentation TimeStamp of the input frame, expressed as a number of
5098 time base units. The time base unit depends on the filter input pad.
5101 Presentation TimeStamp of the input frame, expressed as a number of
5105 position of the frame in the input stream, -1 if this information in
5106 unavailable and/or meaningless (for example in case of synthetic video)
5112 sample aspect ratio of the input frame, expressed in the form
5116 size of the input frame, expressed in the form
5117 @var{width}x@var{height}
5120 interlaced mode ("P" for "progressive", "T" for top field first, "B"
5121 for bottom field first)
5124 1 if the frame is a key frame, 0 otherwise
5127 picture type of the input frame ("I" for an I-frame, "P" for a
5128 P-frame, "B" for a B-frame, "?" for unknown type).
5129 Check also the documentation of the @code{AVPictureType} enum and of
5130 the @code{av_get_picture_type_char} function defined in
5131 @file{libavutil/avutil.h}.
5134 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
5136 @item plane_checksum
5137 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
5138 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
5143 Blur the input video without impacting the outlines.
5145 A description of the accepted options follows.
5148 @item luma_radius, lr
5149 Set the luma radius. The option value must be a float number in
5150 the range [0.1,5.0] that specifies the variance of the gaussian filter
5151 used to blur the image (slower if larger). Default value is 1.0.
5153 @item luma_strength, ls
5154 Set the luma strength. The option value must be a float number
5155 in the range [-1.0,1.0] that configures the blurring. A value included
5156 in [0.0,1.0] will blur the image whereas a value included in
5157 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5159 @item luma_threshold, lt
5160 Set the luma threshold used as a coefficient to determine
5161 whether a pixel should be blurred or not. The option value must be an
5162 integer in the range [-30,30]. A value of 0 will filter all the image,
5163 a value included in [0,30] will filter flat areas and a value included
5164 in [-30,0] will filter edges. Default value is 0.
5166 @item chroma_radius, cr
5167 Set the chroma radius. The option value must be a float number in
5168 the range [0.1,5.0] that specifies the variance of the gaussian filter
5169 used to blur the image (slower if larger). Default value is 1.0.
5171 @item chroma_strength, cs
5172 Set the chroma strength. The option value must be a float number
5173 in the range [-1.0,1.0] that configures the blurring. A value included
5174 in [0.0,1.0] will blur the image whereas a value included in
5175 [-1.0,0.0] will sharpen the image. Default value is 1.0.
5177 @item chroma_threshold, ct
5178 Set the chroma threshold used as a coefficient to determine
5179 whether a pixel should be blurred or not. The option value must be an
5180 integer in the range [-30,30]. A value of 0 will filter all the image,
5181 a value included in [0,30] will filter flat areas and a value included
5182 in [-30,0] will filter edges. Default value is 0.
5185 If a chroma option is not explicitly set, the corresponding luma value
5190 Convert between different stereoscopic image formats.
5192 The filters accept the following options:
5196 Set stereoscopic image format of input.
5198 Available values for input image formats are:
5201 side by side parallel (left eye left, right eye right)
5204 side by side crosseye (right eye left, left eye right)
5207 side by side parallel with half width resolution
5208 (left eye left, right eye right)
5211 side by side crosseye with half width resolution
5212 (right eye left, left eye right)
5215 above-below (left eye above, right eye below)
5218 above-below (right eye above, left eye below)
5221 above-below with half height resolution
5222 (left eye above, right eye below)
5225 above-below with half height resolution
5226 (right eye above, left eye below)
5228 Default value is @samp{sbsl}.
5232 Set stereoscopic image format of output.
5234 Available values for output image formats are all the input formats as well as:
5237 anaglyph red/blue gray
5238 (red filter on left eye, blue filter on right eye)
5241 anaglyph red/green gray
5242 (red filter on left eye, green filter on right eye)
5245 anaglyph red/cyan gray
5246 (red filter on left eye, cyan filter on right eye)
5249 anaglyph red/cyan half colored
5250 (red filter on left eye, cyan filter on right eye)
5253 anaglyph red/cyan color
5254 (red filter on left eye, cyan filter on right eye)
5257 anaglyph red/cyan color optimized with the least squares projection of dubois
5258 (red filter on left eye, cyan filter on right eye)
5261 anaglyph green/magenta gray
5262 (green filter on left eye, magenta filter on right eye)
5265 anaglyph green/magenta half colored
5266 (green filter on left eye, magenta filter on right eye)
5269 anaglyph green/magenta colored
5270 (green filter on left eye, magenta filter on right eye)
5273 anaglyph green/magenta color optimized with the least squares projection of dubois
5274 (green filter on left eye, magenta filter on right eye)
5277 anaglyph yellow/blue gray
5278 (yellow filter on left eye, blue filter on right eye)
5281 anaglyph yellow/blue half colored
5282 (yellow filter on left eye, blue filter on right eye)
5285 anaglyph yellow/blue colored
5286 (yellow filter on left eye, blue filter on right eye)
5289 anaglyph yellow/blue color optimized with the least squares projection of dubois
5290 (yellow filter on left eye, blue filter on right eye)
5293 interleaved rows (left eye has top row, right eye starts on next row)
5296 interleaved rows (right eye has top row, left eye starts on next row)
5299 mono output (left eye only)
5302 mono output (right eye only)
5305 Default value is @samp{arcd}.
5311 Draw subtitles on top of input video using the libass library.
5313 To enable compilation of this filter you need to configure FFmpeg with
5314 @code{--enable-libass}. This filter also requires a build with libavcodec and
5315 libavformat to convert the passed subtitles file to ASS (Advanced Substation
5316 Alpha) subtitles format.
5318 The filter accepts the following options:
5322 Set the filename of the subtitle file to read. It must be specified.
5325 Specify the size of the original video, the video for which the ASS file
5326 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
5327 necessary to correctly scale the fonts if the aspect ratio has been changed.
5330 Set subtitles input character encoding. @code{subtitles} filter only. Only
5331 useful if not UTF-8.
5334 If the first key is not specified, it is assumed that the first value
5335 specifies the @option{filename}.
5337 For example, to render the file @file{sub.srt} on top of the input
5338 video, use the command:
5343 which is equivalent to:
5345 subtitles=filename=sub.srt
5350 Split input video into several identical outputs.
5352 The filter accepts a single parameter which specifies the number of outputs. If
5353 unspecified, it defaults to 2.
5357 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
5359 will create 5 copies of the input video.
5363 [in] split [splitout1][splitout2];
5364 [splitout1] crop=100:100:0:0 [cropout];
5365 [splitout2] pad=200:200:100:100 [padout];
5368 will create two separate outputs from the same input, one cropped and
5373 Scale the input by 2x and smooth using the Super2xSaI (Scale and
5374 Interpolate) pixel art scaling algorithm.
5376 Useful for enlarging pixel art images without reducing sharpness.
5382 Select the most representative frame in a given sequence of consecutive frames.
5384 The filter accepts the following options:
5388 Set the frames batch size to analyze; in a set of @var{n} frames, the filter
5389 will pick one of them, and then handle the next batch of @var{n} frames until
5390 the end. Default is @code{100}.
5393 Since the filter keeps track of the whole frames sequence, a bigger @var{n}
5394 value will result in a higher memory usage, so a high value is not recommended.
5396 @subsection Examples
5400 Extract one picture each 50 frames:
5406 Complete example of a thumbnail creation with @command{ffmpeg}:
5408 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
5414 Tile several successive frames together.
5416 The filter accepts the following options:
5421 Set the grid size (i.e. the number of lines and columns) in the form
5425 Set the maximum number of frames to render in the given area. It must be less
5426 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
5427 the area will be used.
5430 Set the outer border margin in pixels.
5433 Set the inner border thickness (i.e. the number of pixels between frames). For
5434 more advanced padding options (such as having different values for the edges),
5435 refer to the pad video filter.
5439 @subsection Examples
5443 Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie:
5445 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
5447 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
5448 duplicating each output frame to accomodate the originally detected frame
5452 Display @code{5} pictures in an area of @code{3x2} frames,
5453 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
5454 mixed flat and named options:
5456 tile=3x2:nb_frames=5:padding=7:margin=2
5462 Perform various types of temporal field interlacing.
5464 Frames are counted starting from 1, so the first input frame is
5467 The filter accepts the following options:
5472 Specify the mode of the interlacing. This option can also be specified
5473 as a value alone. See below for a list of values for this option.
5475 Available values are:
5479 Move odd frames into the upper field, even into the lower field,
5480 generating a double height frame at half frame rate.
5483 Only output even frames, odd frames are dropped, generating a frame with
5484 unchanged height at half frame rate.
5487 Only output odd frames, even frames are dropped, generating a frame with
5488 unchanged height at half frame rate.
5491 Expand each frame to full height, but pad alternate lines with black,
5492 generating a frame with double height at the same input frame rate.
5494 @item interleave_top, 4
5495 Interleave the upper field from odd frames with the lower field from
5496 even frames, generating a frame with unchanged height at half frame rate.
5498 @item interleave_bottom, 5
5499 Interleave the lower field from odd frames with the upper field from
5500 even frames, generating a frame with unchanged height at half frame rate.
5502 @item interlacex2, 6
5503 Double frame rate with unchanged height. Frames are inserted each
5504 containing the second temporal field from the previous input frame and
5505 the first temporal field from the next input frame. This mode relies on
5506 the top_field_first flag. Useful for interlaced video displays with no
5507 field synchronisation.
5510 Numeric values are deprecated but are accepted for backward
5511 compatibility reasons.
5513 Default mode is @code{merge}.
5516 Specify flags influencing the filter process.
5518 Available value for @var{flags} is:
5521 @item low_pass_filter, vlfp
5522 Enable vertical low-pass filtering in the filter.
5523 Vertical low-pass filtering is required when creating an interlaced
5524 destination from a progressive source which contains high-frequency
5525 vertical detail. Filtering will reduce interlace 'twitter' and Moire
5528 Vertical low-pass filtering can only be enabled for @option{mode}
5529 @var{interleave_top} and @var{interleave_bottom}.
5536 Transpose rows with columns in the input video and optionally flip it.
5538 This filter accepts the following options:
5543 The direction of the transpose.
5546 @item 0, 4, cclock_flip
5547 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
5555 Rotate by 90 degrees clockwise, that is:
5563 Rotate by 90 degrees counterclockwise, that is:
5570 @item 3, 7, clock_flip
5571 Rotate by 90 degrees clockwise and vertically flip, that is:
5579 For values between 4-7, the transposition is only done if the input
5580 video geometry is portrait and not landscape. These values are
5581 deprecated, the @code{passthrough} option should be used instead.
5584 Do not apply the transposition if the input geometry matches the one
5585 specified by the specified value. It accepts the following values:
5588 Always apply transposition.
5590 Preserve portrait geometry (when @var{height} >= @var{width}).
5592 Preserve landscape geometry (when @var{width} >= @var{height}).
5595 Default value is @code{none}.
5598 For example to rotate by 90 degrees clockwise and preserve portrait
5601 transpose=dir=1:passthrough=portrait
5604 The command above can also be specified as:
5606 transpose=1:portrait
5611 Sharpen or blur the input video.
5613 It accepts the following parameters:
5616 @item luma_msize_x, lx
5617 @item chroma_msize_x, cx
5618 Set the luma/chroma matrix horizontal size. It must be an odd integer
5619 between 3 and 63, default value is 5.
5621 @item luma_msize_y, ly
5622 @item chroma_msize_y, cy
5623 Set the luma/chroma matrix vertical size. It must be an odd integer
5624 between 3 and 63, default value is 5.
5626 @item luma_amount, la
5627 @item chroma_amount, ca
5628 Set the luma/chroma effect strength. It can be a float number,
5629 reasonable values lay between -1.5 and 1.5.
5631 Negative values will blur the input video, while positive values will
5632 sharpen it, a value of zero will disable the effect.
5634 Default value is 1.0 for @option{luma_amount}, 0.0 for
5635 @option{chroma_amount}.
5638 All parameters are optional and default to the
5639 equivalent of the string '5:5:1.0:5:5:0.0'.
5641 @subsection Examples
5645 Apply strong luma sharpen effect:
5647 unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
5651 Apply strong blur of both luma and chroma parameters:
5653 unsharp=7:7:-2:7:7:-2
5659 Flip the input video vertically.
5662 ffmpeg -i in.avi -vf "vflip" out.avi
5667 Deinterlace the input video ("yadif" means "yet another deinterlacing
5670 This filter accepts the following options:
5676 The interlacing mode to adopt, accepts one of the following values:
5680 output 1 frame for each frame
5682 output 1 frame for each field
5683 @item 2, send_frame_nospatial
5684 like @code{send_frame} but skip spatial interlacing check
5685 @item 3, send_field_nospatial
5686 like @code{send_field} but skip spatial interlacing check
5689 Default value is @code{send_frame}.
5692 The picture field parity assumed for the input interlaced video, accepts one of
5693 the following values:
5697 assume top field first
5699 assume bottom field first
5701 enable automatic detection
5704 Default value is @code{auto}.
5705 If interlacing is unknown or decoder does not export this information,
5706 top field first will be assumed.
5709 Specify which frames to deinterlace. Accept one of the following
5714 deinterlace all frames
5716 only deinterlace frames marked as interlaced
5719 Default value is @code{all}.
5722 @c man end VIDEO FILTERS
5724 @chapter Video Sources
5725 @c man begin VIDEO SOURCES
5727 Below is a description of the currently available video sources.
5731 Buffer video frames, and make them available to the filter chain.
5733 This source is mainly intended for a programmatic use, in particular
5734 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
5736 It accepts a list of options in the form of @var{key}=@var{value} pairs
5737 separated by ":". A description of the accepted options follows.
5742 Specify the size (width and height) of the buffered video frames.
5745 A string representing the pixel format of the buffered video frames.
5746 It may be a number corresponding to a pixel format, or a pixel format
5750 Specify the timebase assumed by the timestamps of the buffered frames.
5753 Specify the frame rate expected for the video stream.
5756 Specify the sample aspect ratio assumed by the video frames.
5759 Specify the optional parameters to be used for the scale filter which
5760 is automatically inserted when an input change is detected in the
5761 input size or format.
5766 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
5769 will instruct the source to accept video frames with size 320x240 and
5770 with format "yuv410p", assuming 1/24 as the timestamps timebase and
5771 square pixels (1:1 sample aspect ratio).
5772 Since the pixel format with name "yuv410p" corresponds to the number 6
5773 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
5774 this example corresponds to:
5776 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
5779 Alternatively, the options can be specified as a flat string, but this
5780 syntax is deprecated:
5782 @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}]
5786 Create a pattern generated by an elementary cellular automaton.
5788 The initial state of the cellular automaton can be defined through the
5789 @option{filename}, and @option{pattern} options. If such options are
5790 not specified an initial state is created randomly.
5792 At each new frame a new row in the video is filled with the result of
5793 the cellular automaton next generation. The behavior when the whole
5794 frame is filled is defined by the @option{scroll} option.
5796 This source accepts the following options:
5800 Read the initial cellular automaton state, i.e. the starting row, from
5802 In the file, each non-whitespace character is considered an alive
5803 cell, a newline will terminate the row, and further characters in the
5804 file will be ignored.
5807 Read the initial cellular automaton state, i.e. the starting row, from
5808 the specified string.
5810 Each non-whitespace character in the string is considered an alive
5811 cell, a newline will terminate the row, and further characters in the
5812 string will be ignored.
5815 Set the video rate, that is the number of frames generated per second.
5818 @item random_fill_ratio, ratio
5819 Set the random fill ratio for the initial cellular automaton row. It
5820 is a floating point number value ranging from 0 to 1, defaults to
5823 This option is ignored when a file or a pattern is specified.
5825 @item random_seed, seed
5826 Set the seed for filling randomly the initial row, must be an integer
5827 included between 0 and UINT32_MAX. If not specified, or if explicitly
5828 set to -1, the filter will try to use a good random seed on a best
5832 Set the cellular automaton rule, it is a number ranging from 0 to 255.
5833 Default value is 110.
5836 Set the size of the output video.
5838 If @option{filename} or @option{pattern} is specified, the size is set
5839 by default to the width of the specified initial state row, and the
5840 height is set to @var{width} * PHI.
5842 If @option{size} is set, it must contain the width of the specified
5843 pattern string, and the specified pattern will be centered in the
5846 If a filename or a pattern string is not specified, the size value
5847 defaults to "320x518" (used for a randomly generated initial state).
5850 If set to 1, scroll the output upward when all the rows in the output
5851 have been already filled. If set to 0, the new generated row will be
5852 written over the top row just after the bottom row is filled.
5855 @item start_full, full
5856 If set to 1, completely fill the output with generated rows before
5857 outputting the first frame.
5858 This is the default behavior, for disabling set the value to 0.
5861 If set to 1, stitch the left and right row edges together.
5862 This is the default behavior, for disabling set the value to 0.
5865 @subsection Examples
5869 Read the initial state from @file{pattern}, and specify an output of
5872 cellauto=f=pattern:s=200x400
5876 Generate a random initial row with a width of 200 cells, with a fill
5879 cellauto=ratio=2/3:s=200x200
5883 Create a pattern generated by rule 18 starting by a single alive cell
5884 centered on an initial row with width 100:
5886 cellauto=p=@@:s=100x400:full=0:rule=18
5890 Specify a more elaborated initial pattern:
5892 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
5899 Generate a Mandelbrot set fractal, and progressively zoom towards the
5900 point specified with @var{start_x} and @var{start_y}.
5902 This source accepts the following options:
5907 Set the terminal pts value. Default value is 400.
5910 Set the terminal scale value.
5911 Must be a floating point value. Default value is 0.3.
5914 Set the inner coloring mode, that is the algorithm used to draw the
5915 Mandelbrot fractal internal region.
5917 It shall assume one of the following values:
5922 Show time until convergence.
5924 Set color based on point closest to the origin of the iterations.
5929 Default value is @var{mincol}.
5932 Set the bailout value. Default value is 10.0.
5935 Set the maximum of iterations performed by the rendering
5936 algorithm. Default value is 7189.
5939 Set outer coloring mode.
5940 It shall assume one of following values:
5942 @item iteration_count
5943 Set iteration cound mode.
5944 @item normalized_iteration_count
5945 set normalized iteration count mode.
5947 Default value is @var{normalized_iteration_count}.
5950 Set frame rate, expressed as number of frames per second. Default
5954 Set frame size. Default value is "640x480".
5957 Set the initial scale value. Default value is 3.0.
5960 Set the initial x position. Must be a floating point value between
5961 -100 and 100. Default value is -0.743643887037158704752191506114774.
5964 Set the initial y position. Must be a floating point value between
5965 -100 and 100. Default value is -0.131825904205311970493132056385139.
5970 Generate various test patterns, as generated by the MPlayer test filter.
5972 The size of the generated video is fixed, and is 256x256.
5973 This source is useful in particular for testing encoding features.
5975 This source accepts the following options:
5980 Specify the frame rate of the sourced video, as the number of frames
5981 generated per second. It has to be a string in the format
5982 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5983 number or a valid video frame rate abbreviation. The default value is
5987 Set the video duration of the sourced video. The accepted syntax is:
5992 See also the function @code{av_parse_time()}.
5994 If not specified, or the expressed duration is negative, the video is
5995 supposed to be generated forever.
5999 Set the number or the name of the test to perform. Supported tests are:
6014 Default value is "all", which will cycle through the list of all tests.
6017 For example the following:
6022 will generate a "dc_luma" test pattern.
6026 Provide a frei0r source.
6028 To enable compilation of this filter you need to install the frei0r
6029 header and configure FFmpeg with @code{--enable-frei0r}.
6031 This source accepts the following options:
6036 The size of the video to generate, may be a string of the form
6037 @var{width}x@var{height} or a frame size abbreviation.
6040 Framerate of the generated video, may be a string of the form
6041 @var{num}/@var{den} or a frame rate abbreviation.
6044 The name to the frei0r source to load. For more information regarding frei0r and
6045 how to set the parameters read the section @ref{frei0r} in the description of
6049 A '|'-separated list of parameters to pass to the frei0r source.
6053 For example, to generate a frei0r partik0l source with size 200x200
6054 and frame rate 10 which is overlayed on the overlay filter main input:
6056 frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
6061 Generate a life pattern.
6063 This source is based on a generalization of John Conway's life game.
6065 The sourced input represents a life grid, each pixel represents a cell
6066 which can be in one of two possible states, alive or dead. Every cell
6067 interacts with its eight neighbours, which are the cells that are
6068 horizontally, vertically, or diagonally adjacent.
6070 At each interaction the grid evolves according to the adopted rule,
6071 which specifies the number of neighbor alive cells which will make a
6072 cell stay alive or born. The @option{rule} option allows to specify
6075 This source accepts the following options:
6079 Set the file from which to read the initial grid state. In the file,
6080 each non-whitespace character is considered an alive cell, and newline
6081 is used to delimit the end of each row.
6083 If this option is not specified, the initial grid is generated
6087 Set the video rate, that is the number of frames generated per second.
6090 @item random_fill_ratio, ratio
6091 Set the random fill ratio for the initial random grid. It is a
6092 floating point number value ranging from 0 to 1, defaults to 1/PHI.
6093 It is ignored when a file is specified.
6095 @item random_seed, seed
6096 Set the seed for filling the initial random grid, must be an integer
6097 included between 0 and UINT32_MAX. If not specified, or if explicitly
6098 set to -1, the filter will try to use a good random seed on a best
6104 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
6105 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
6106 @var{NS} specifies the number of alive neighbor cells which make a
6107 live cell stay alive, and @var{NB} the number of alive neighbor cells
6108 which make a dead cell to become alive (i.e. to "born").
6109 "s" and "b" can be used in place of "S" and "B", respectively.
6111 Alternatively a rule can be specified by an 18-bits integer. The 9
6112 high order bits are used to encode the next cell state if it is alive
6113 for each number of neighbor alive cells, the low order bits specify
6114 the rule for "borning" new cells. Higher order bits encode for an
6115 higher number of neighbor cells.
6116 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
6117 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
6119 Default value is "S23/B3", which is the original Conway's game of life
6120 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
6121 cells, and will born a new cell if there are three alive cells around
6125 Set the size of the output video.
6127 If @option{filename} is specified, the size is set by default to the
6128 same size of the input file. If @option{size} is set, it must contain
6129 the size specified in the input file, and the initial grid defined in
6130 that file is centered in the larger resulting area.
6132 If a filename is not specified, the size value defaults to "320x240"
6133 (used for a randomly generated initial grid).
6136 If set to 1, stitch the left and right grid edges together, and the
6137 top and bottom edges also. Defaults to 1.
6140 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
6141 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
6142 value from 0 to 255.
6145 Set the color of living (or new born) cells.
6148 Set the color of dead cells. If @option{mold} is set, this is the first color
6149 used to represent a dead cell.
6152 Set mold color, for definitely dead and moldy cells.
6155 @subsection Examples
6159 Read a grid from @file{pattern}, and center it on a grid of size
6162 life=f=pattern:s=300x300
6166 Generate a random grid of size 200x200, with a fill ratio of 2/3:
6168 life=ratio=2/3:s=200x200
6172 Specify a custom rule for evolving a randomly generated grid:
6178 Full example with slow death effect (mold) using @command{ffplay}:
6180 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
6184 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
6186 The @code{color} source provides an uniformly colored input.
6188 The @code{nullsrc} source returns unprocessed video frames. It is
6189 mainly useful to be employed in analysis / debugging tools, or as the
6190 source for filters which ignore the input data.
6192 The @code{rgbtestsrc} source generates an RGB test pattern useful for
6193 detecting RGB vs BGR issues. You should see a red, green and blue
6194 stripe from top to bottom.
6196 The @code{smptebars} source generates a color bars pattern, based on
6197 the SMPTE Engineering Guideline EG 1-1990.
6199 The @code{testsrc} source generates a test video pattern, showing a
6200 color pattern, a scrolling gradient and a timestamp. This is mainly
6201 intended for testing purposes.
6203 The sources accept the following options:
6208 Specify the color of the source, only used in the @code{color}
6209 source. It can be the name of a color (case insensitive match) or a
6210 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
6211 default value is "black".
6214 Specify the size of the sourced video, it may be a string of the form
6215 @var{width}x@var{height}, or the name of a size abbreviation. The
6216 default value is "320x240".
6219 Specify the frame rate of the sourced video, as the number of frames
6220 generated per second. It has to be a string in the format
6221 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
6222 number or a valid video frame rate abbreviation. The default value is
6226 Set the sample aspect ratio of the sourced video.
6229 Set the video duration of the sourced video. The accepted syntax is:
6231 [-]HH[:MM[:SS[.m...]]]
6234 See also the function @code{av_parse_time()}.
6236 If not specified, or the expressed duration is negative, the video is
6237 supposed to be generated forever.
6240 Set the number of decimals to show in the timestamp, only used in the
6241 @code{testsrc} source.
6243 The displayed timestamp value will correspond to the original
6244 timestamp value multiplied by the power of 10 of the specified
6245 value. Default value is 0.
6248 For example the following:
6250 testsrc=duration=5.3:size=qcif:rate=10
6253 will generate a video with a duration of 5.3 seconds, with size
6254 176x144 and a frame rate of 10 frames per second.
6256 The following graph description will generate a red source
6257 with an opacity of 0.2, with size "qcif" and a frame rate of 10
6260 color=c=red@@0.2:s=qcif:r=10
6263 If the input content is to be ignored, @code{nullsrc} can be used. The
6264 following command generates noise in the luminance plane by employing
6265 the @code{geq} filter:
6267 nullsrc=s=256x256, geq=random(1)*255:128:128
6270 @c man end VIDEO SOURCES
6272 @chapter Video Sinks
6273 @c man begin VIDEO SINKS
6275 Below is a description of the currently available video sinks.
6279 Buffer video frames, and make them available to the end of the filter
6282 This sink is mainly intended for a programmatic use, in particular
6283 through the interface defined in @file{libavfilter/buffersink.h}.
6285 It does not require a string parameter in input, but you need to
6286 specify a pointer to a list of supported pixel formats terminated by
6287 -1 in the opaque parameter provided to @code{avfilter_init_filter}
6288 when initializing this sink.
6292 Null video sink, do absolutely nothing with the input video. It is
6293 mainly useful as a template and to be employed in analysis / debugging
6296 @c man end VIDEO SINKS
6298 @chapter Multimedia Filters
6299 @c man begin MULTIMEDIA FILTERS
6301 Below is a description of the currently available multimedia filters.
6303 @section aperms, perms
6305 Set read/write permissions for the output frames.
6307 These filters are mainly aimed at developers to test direct path in the
6308 following filter in the filtergraph.
6310 The filters accept the following options:
6314 Select the permissions mode.
6316 It accepts the following values:
6319 Do nothing. This is the default.
6321 Set all the output frames read-only.
6323 Set all the output frames directly writable.
6325 Make the frame read-only if writable, and writable if read-only.
6327 Set each output frame read-only or writable randomly.
6331 Set the seed for the @var{random} mode, must be an integer included between
6332 @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to
6333 @code{-1}, the filter will try to use a good random seed on a best effort
6337 Note: in case of auto-inserted filter between the permission filter and the
6338 following one, the permission might not be received as expected in that
6339 following filter. Inserting a @ref{format} or @ref{aformat} filter before the
6340 perms/aperms filter can avoid this problem.
6343 Add a phasing effect to the input audio.
6345 A phaser filter creates series of peaks and troughs in the frequency spectrum.
6346 The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
6348 A description of the accepted parameters follows.
6352 Set input gain. Default is 0.4.
6355 Set output gain. Default is 0.74
6358 Set delay in milliseconds. Default is 3.0.
6361 Set decay. Default is 0.4.
6364 Set modulation speed in Hz. Default is 0.5.
6367 Set modulation type. Default is triangular.
6369 It accepts the following values:
6376 @section aselect, select
6377 Select frames to pass in output.
6379 This filter accepts the following options:
6384 An expression, which is evaluated for each input frame. If the expression is
6385 evaluated to a non-zero value, the frame is selected and passed to the output,
6386 otherwise it is discarded.
6390 The expression can contain the following constants:
6394 the sequential number of the filtered frame, starting from 0
6397 the sequential number of the selected frame, starting from 0
6399 @item prev_selected_n
6400 the sequential number of the last selected frame, NAN if undefined
6403 timebase of the input timestamps
6406 the PTS (Presentation TimeStamp) of the filtered video frame,
6407 expressed in @var{TB} units, NAN if undefined
6410 the PTS (Presentation TimeStamp) of the filtered video frame,
6411 expressed in seconds, NAN if undefined
6414 the PTS of the previously filtered video frame, NAN if undefined
6416 @item prev_selected_pts
6417 the PTS of the last previously filtered video frame, NAN if undefined
6419 @item prev_selected_t
6420 the PTS of the last previously selected video frame, NAN if undefined
6423 the PTS of the first video frame in the video, NAN if undefined
6426 the time of the first video frame in the video, NAN if undefined
6428 @item pict_type @emph{(video only)}
6429 the type of the filtered frame, can assume one of the following
6441 @item interlace_type @emph{(video only)}
6442 the frame interlace type, can assume one of the following values:
6445 the frame is progressive (not interlaced)
6447 the frame is top-field-first
6449 the frame is bottom-field-first
6452 @item consumed_sample_n @emph{(audio only)}
6453 the number of selected samples before the current frame
6455 @item samples_n @emph{(audio only)}
6456 the number of samples in the current frame
6458 @item sample_rate @emph{(audio only)}
6459 the input sample rate
6462 1 if the filtered frame is a key-frame, 0 otherwise
6465 the position in the file of the filtered frame, -1 if the information
6466 is not available (e.g. for synthetic video)
6468 @item scene @emph{(video only)}
6469 value between 0 and 1 to indicate a new scene; a low value reflects a low
6470 probability for the current frame to introduce a new scene, while a higher
6471 value means the current frame is more likely to be one (see the example below)
6475 The default value of the select expression is "1".
6477 @subsection Examples
6481 Select all frames in input:
6486 The example above is the same as:
6498 Select only I-frames:
6500 select='eq(pict_type\,I)'
6504 Select one frame every 100:
6506 select='not(mod(n\,100))'
6510 Select only frames contained in the 10-20 time interval:
6512 select='gte(t\,10)*lte(t\,20)'
6516 Select only I frames contained in the 10-20 time interval:
6518 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
6522 Select frames with a minimum distance of 10 seconds:
6524 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
6528 Use aselect to select only audio frames with samples number > 100:
6530 aselect='gt(samples_n\,100)'
6534 Create a mosaic of the first scenes:
6536 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
6539 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
6543 @section asendcmd, sendcmd
6545 Send commands to filters in the filtergraph.
6547 These filters read commands to be sent to other filters in the
6550 @code{asendcmd} must be inserted between two audio filters,
6551 @code{sendcmd} must be inserted between two video filters, but apart
6552 from that they act the same way.
6554 The specification of commands can be provided in the filter arguments
6555 with the @var{commands} option, or in a file specified by the
6556 @var{filename} option.
6558 These filters accept the following options:
6561 Set the commands to be read and sent to the other filters.
6563 Set the filename of the commands to be read and sent to the other
6567 @subsection Commands syntax
6569 A commands description consists of a sequence of interval
6570 specifications, comprising a list of commands to be executed when a
6571 particular event related to that interval occurs. The occurring event
6572 is typically the current frame time entering or leaving a given time
6575 An interval is specified by the following syntax:
6577 @var{START}[-@var{END}] @var{COMMANDS};
6580 The time interval is specified by the @var{START} and @var{END} times.
6581 @var{END} is optional and defaults to the maximum time.
6583 The current frame time is considered within the specified interval if
6584 it is included in the interval [@var{START}, @var{END}), that is when
6585 the time is greater or equal to @var{START} and is lesser than
6588 @var{COMMANDS} consists of a sequence of one or more command
6589 specifications, separated by ",", relating to that interval. The
6590 syntax of a command specification is given by:
6592 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
6595 @var{FLAGS} is optional and specifies the type of events relating to
6596 the time interval which enable sending the specified command, and must
6597 be a non-null sequence of identifier flags separated by "+" or "|" and
6598 enclosed between "[" and "]".
6600 The following flags are recognized:
6603 The command is sent when the current frame timestamp enters the
6604 specified interval. In other words, the command is sent when the
6605 previous frame timestamp was not in the given interval, and the
6609 The command is sent when the current frame timestamp leaves the
6610 specified interval. In other words, the command is sent when the
6611 previous frame timestamp was in the given interval, and the
6615 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
6618 @var{TARGET} specifies the target of the command, usually the name of
6619 the filter class or a specific filter instance name.
6621 @var{COMMAND} specifies the name of the command for the target filter.
6623 @var{ARG} is optional and specifies the optional list of argument for
6624 the given @var{COMMAND}.
6626 Between one interval specification and another, whitespaces, or
6627 sequences of characters starting with @code{#} until the end of line,
6628 are ignored and can be used to annotate comments.
6630 A simplified BNF description of the commands specification syntax
6633 @var{COMMAND_FLAG} ::= "enter" | "leave"
6634 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
6635 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
6636 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
6637 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
6638 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
6641 @subsection Examples
6645 Specify audio tempo change at second 4:
6647 asendcmd=c='4.0 atempo tempo 1.5',atempo
6651 Specify a list of drawtext and hue commands in a file.
6653 # show text in the interval 5-10
6654 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
6655 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
6657 # desaturate the image in the interval 15-20
6658 15.0-20.0 [enter] hue reinit s=0,
6659 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
6660 [leave] hue reinit s=1,
6661 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
6663 # apply an exponential saturation fade-out effect, starting from time 25
6664 25 [enter] hue s=exp(t-25)
6667 A filtergraph allowing to read and process the above command list
6668 stored in a file @file{test.cmd}, can be specified with:
6670 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
6675 @section asetpts, setpts
6677 Change the PTS (presentation timestamp) of the input frames.
6679 @code{asetpts} works on audio frames, @code{setpts} on video frames.
6681 This filter accepts the following options:
6686 The expression which is evaluated for each frame to construct its timestamp.
6690 The expression is evaluated through the eval API and can contain the following
6695 frame rate, only defined for constant frame-rate video
6698 the presentation timestamp in input
6701 the count of the input frame, starting from 0.
6703 @item NB_CONSUMED_SAMPLES
6704 the number of consumed samples, not including the current frame (only
6708 the number of samples in the current frame (only audio)
6714 the PTS of the first frame
6717 the time in seconds of the first frame
6720 tell if the current frame is interlaced
6723 the time in seconds of the current frame
6729 original position in the file of the frame, or undefined if undefined
6730 for the current frame
6736 previous input time in seconds
6742 previous output time in seconds
6745 wallclock (RTC) time in microseconds. This is deprecated, use time(0)
6749 wallclock (RTC) time at the start of the movie in microseconds
6752 @subsection Examples
6756 Start counting PTS from zero
6762 Apply fast motion effect:
6768 Apply slow motion effect:
6774 Set fixed rate of 25 frames per second:
6780 Set fixed rate 25 fps with some jitter:
6782 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
6786 Apply an offset of 10 seconds to the input PTS:
6792 Generate timestamps from a "live source" and rebase onto the current timebase:
6794 setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
6800 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
6801 it unchanged. By default, it logs a message at a frequency of 10Hz with the
6802 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
6803 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
6805 The filter also has a video output (see the @var{video} option) with a real
6806 time graph to observe the loudness evolution. The graphic contains the logged
6807 message mentioned above, so it is not printed anymore when this option is set,
6808 unless the verbose logging is set. The main graphing area contains the
6809 short-term loudness (3 seconds of analysis), and the gauge on the right is for
6810 the momentary loudness (400 milliseconds).
6812 More information about the Loudness Recommendation EBU R128 on
6813 @url{http://tech.ebu.ch/loudness}.
6815 The filter accepts the following options:
6820 Activate the video output. The audio stream is passed unchanged whether this
6821 option is set or no. The video stream will be the first output stream if
6822 activated. Default is @code{0}.
6825 Set the video size. This option is for video only. Default and minimum
6826 resolution is @code{640x480}.
6829 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
6830 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
6831 other integer value between this range is allowed.
6834 Set metadata injection. If set to @code{1}, the audio input will be segmented
6835 into 100ms output frames, each of them containing various loudness information
6836 in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}.
6838 Default is @code{0}.
6841 Force the frame logging level.
6843 Available values are:
6846 information logging level
6848 verbose logging level
6851 By default, the logging level is set to @var{info}. If the @option{video} or
6852 the @option{metadata} options are set, it switches to @var{verbose}.
6855 @subsection Examples
6859 Real-time graph using @command{ffplay}, with a EBU scale meter +18:
6861 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
6865 Run an analysis with @command{ffmpeg}:
6867 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
6871 @section settb, asettb
6873 Set the timebase to use for the output frames timestamps.
6874 It is mainly useful for testing timebase configuration.
6876 This filter accepts the following options:
6881 The expression which is evaluated into the output timebase.
6885 The value for @option{tb} is an arithmetic expression representing a
6886 rational. The expression can contain the constants "AVTB" (the default
6887 timebase), "intb" (the input timebase) and "sr" (the sample rate,
6888 audio only). Default value is "intb".
6890 @subsection Examples
6894 Set the timebase to 1/25:
6900 Set the timebase to 1/10:
6906 Set the timebase to 1001/1000:
6912 Set the timebase to 2*intb:
6918 Set the default timebase value:
6926 Concatenate audio and video streams, joining them together one after the
6929 The filter works on segments of synchronized video and audio streams. All
6930 segments must have the same number of streams of each type, and that will
6931 also be the number of streams at output.
6933 The filter accepts the following options:
6938 Set the number of segments. Default is 2.
6941 Set the number of output video streams, that is also the number of video
6942 streams in each segment. Default is 1.
6945 Set the number of output audio streams, that is also the number of video
6946 streams in each segment. Default is 0.
6949 Activate unsafe mode: do not fail if segments have a different format.
6953 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
6954 @var{a} audio outputs.
6956 There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first
6957 segment, in the same order as the outputs, then the inputs for the second
6960 Related streams do not always have exactly the same duration, for various
6961 reasons including codec frame size or sloppy authoring. For that reason,
6962 related synchronized streams (e.g. a video and its audio track) should be
6963 concatenated at once. The concat filter will use the duration of the longest
6964 stream in each segment (except the last one), and if necessary pad shorter
6965 audio streams with silence.
6967 For this filter to work correctly, all segments must start at timestamp 0.
6969 All corresponding streams must have the same parameters in all segments; the
6970 filtering system will automatically select a common pixel format for video
6971 streams, and a common sample format, sample rate and channel layout for
6972 audio streams, but other settings, such as resolution, must be converted
6973 explicitly by the user.
6975 Different frame rates are acceptable but will result in variable frame rate
6976 at output; be sure to configure the output file to handle it.
6978 @subsection Examples
6982 Concatenate an opening, an episode and an ending, all in bilingual version
6983 (video in stream 0, audio in streams 1 and 2):
6985 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
6986 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
6987 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
6988 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
6992 Concatenate two parts, handling audio and video separately, using the
6993 (a)movie sources, and adjusting the resolution:
6995 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
6996 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
6997 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
6999 Note that a desync will happen at the stitch if the audio and video streams
7000 do not have exactly the same duration in the first file.
7004 @section showspectrum
7006 Convert input audio to a video output, representing the audio frequency
7009 The filter accepts the following options:
7013 Specify the video size for the output. Default value is @code{640x512}.
7016 Specify if the spectrum should slide along the window. Default value is
7020 Specify display mode.
7022 It accepts the following values:
7025 all channels are displayed in the same row
7027 all channels are displayed in separate rows
7030 Default value is @samp{combined}.
7033 Specify display color mode.
7035 It accepts the following values:
7038 each channel is displayed in a separate color
7040 each channel is is displayed using the same color scheme
7043 Default value is @samp{channel}.
7046 Specify scale used for calculating intensity color values.
7048 It accepts the following values:
7053 square root, default
7060 Default value is @samp{sqrt}.
7063 Set saturation modifier for displayed colors. Negative values provide
7064 alternative color scheme. @code{0} is no saturation at all.
7065 Saturation must be in [-10.0, 10.0] range.
7066 Default value is @code{1}.
7069 The usage is very similar to the showwaves filter; see the examples in that
7072 @subsection Examples
7076 Large window with logarithmic color scaling:
7078 showspectrum=s=1280x480:scale=log
7082 Complete example for a colored and sliding spectrum per channel using @command{ffplay}:
7084 ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
7085 [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
7091 Convert input audio to a video output, representing the samples waves.
7093 The filter accepts the following named parameters:
7098 Available values are:
7101 Draw a point for each sample.
7104 Draw a vertical line for each sample.
7107 Default value is @code{point}.
7110 Set the number of samples which are printed on the same column. A
7111 larger value will decrease the frame rate. Must be a positive
7112 integer. This option can be set only if the value for @var{rate}
7113 is not explicitly specified.
7116 Set the (approximate) output frame rate. This is done by setting the
7117 option @var{n}. Default value is "25".
7120 Specify the video size for the output. Default value is "600x240".
7123 @subsection Examples
7127 Output the input file audio and the corresponding video representation
7130 amovie=a.mp3,asplit[out0],showwaves[out1]
7134 Create a synthetic signal and show it with showwaves, forcing a
7135 frame rate of 30 frames per second:
7137 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
7141 @c man end MULTIMEDIA FILTERS
7143 @chapter Multimedia Sources
7144 @c man begin MULTIMEDIA SOURCES
7146 Below is a description of the currently available multimedia sources.
7150 This is the same as @ref{movie} source, except it selects an audio
7156 Read audio and/or video stream(s) from a movie container.
7158 This filter accepts the following options:
7162 The name of the resource to read (not necessarily a file but also a device or a
7163 stream accessed through some protocol).
7165 @item format_name, f
7166 Specifies the format assumed for the movie to read, and can be either
7167 the name of a container or an input device. If not specified the
7168 format is guessed from @var{movie_name} or by probing.
7170 @item seek_point, sp
7171 Specifies the seek point in seconds, the frames will be output
7172 starting from this seek point, the parameter is evaluated with
7173 @code{av_strtod} so the numerical value may be suffixed by an IS
7174 postfix. Default value is "0".
7177 Specifies the streams to read. Several streams can be specified,
7178 separated by "+". The source will then have as many outputs, in the
7179 same order. The syntax is explained in the ``Stream specifiers''
7180 section in the ffmpeg manual. Two special names, "dv" and "da" specify
7181 respectively the default (best suited) video and audio stream. Default
7182 is "dv", or "da" if the filter is called as "amovie".
7184 @item stream_index, si
7185 Specifies the index of the video stream to read. If the value is -1,
7186 the best suited video stream will be automatically selected. Default
7187 value is "-1". Deprecated. If the filter is called "amovie", it will select
7188 audio instead of video.
7191 Specifies how many times to read the stream in sequence.
7192 If the value is less than 1, the stream will be read again and again.
7193 Default value is "1".
7195 Note that when the movie is looped the source timestamps are not
7196 changed, so it will generate non monotonically increasing timestamps.
7199 This filter allows to overlay a second video on top of main input of
7200 a filtergraph as shown in this graph:
7202 input -----------> deltapts0 --> overlay --> output
7205 movie --> scale--> deltapts1 -------+
7208 @subsection Examples
7212 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
7213 on top of the input labelled as "in":
7215 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
7216 [in] setpts=PTS-STARTPTS [main];
7217 [main][over] overlay=16:16 [out]
7221 Read from a video4linux2 device, and overlay it on top of the input
7224 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
7225 [in] setpts=PTS-STARTPTS [main];
7226 [main][over] overlay=16:16 [out]
7230 Read the first video stream and the audio stream with id 0x81 from
7231 dvd.vob; the video is connected to the pad named "video" and the audio is
7232 connected to the pad named "audio":
7234 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
7238 @c man end MULTIMEDIA SOURCES