1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 Libavfilter is the filtering API of FFmpeg. It is the substitute of
7 the now deprecated 'vhooks' and started as a Google Summer of Code
10 Audio filtering integration into the main FFmpeg repository is a work in
11 progress, so audio API and ABI should not be considered stable yet.
13 In libavfilter, it is possible for filters to have multiple inputs and
15 To illustrate the sorts of things that are possible, we can
16 use a complex filter graph. For example, the following one:
19 input --> split --> fifo -----------------------> overlay --> output
22 +------> fifo --> crop --> vflip --------+
25 splits the stream in two streams, sends one stream through the crop filter
26 and the vflip filter before merging it back with the other stream by
27 overlaying it on top. You can use the following command to achieve this:
30 ffmpeg -i input -vf "[in] split [T1], fifo, [T2] overlay=0:H/2 [out]; [T1] fifo, crop=iw:ih/2:0:ih/2, vflip [T2]" output
33 The result will be that in output the top half of the video is mirrored
36 Filters are loaded using the @var{-vf} or @var{-af} option passed to
37 @command{ffmpeg} or to @command{ffplay}. Filters in the same linear
38 chain are separated by commas. In our example, @var{split, fifo,
39 overlay} are in one linear chain, and @var{fifo, crop, vflip} are in
40 another. The points where the linear chains join are labeled by names
41 enclosed in square brackets. In our example, that is @var{[T1]} and
42 @var{[T2]}. The special labels @var{[in]} and @var{[out]} are the points
43 where video is input and output.
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 filter graph 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, and are described in the filter
143 The list of arguments can be quoted using the character "'" as initial
144 and ending mark, and the character '\' for escaping the characters
145 within the quoted text; otherwise the argument string is considered
146 terminated when the next special character (belonging to the set
147 "[]=;,") is encountered.
149 The name and arguments of the filter are optionally preceded and
150 followed by a list of link labels.
151 A link label allows to name a link and associate it to a filter output
152 or input pad. The preceding labels @var{in_link_1}
153 ... @var{in_link_N}, are associated to the filter input pads,
154 the following labels @var{out_link_1} ... @var{out_link_M}, are
155 associated to the output pads.
157 When two link labels with the same name are found in the
158 filtergraph, a link between the corresponding input and output pad is
161 If an output pad is not labelled, it is linked by default to the first
162 unlabelled input pad of the next filter in the filterchain.
163 For example in the filterchain:
165 nullsrc, split[L1], [L2]overlay, nullsink
167 the split filter instance has two output pads, and the overlay filter
168 instance two input pads. The first output pad of split is labelled
169 "L1", the first input pad of overlay is labelled "L2", and the second
170 output pad of split is linked to the second input pad of overlay,
171 which are both unlabelled.
173 In a complete filterchain all the unlabelled filter input and output
174 pads must be connected. A filtergraph is considered valid if all the
175 filter input and output pads of all the filterchains are connected.
177 Libavfilter will automatically insert scale filters where format
178 conversion is required. It is possible to specify swscale flags
179 for those automatically inserted scalers by prepending
180 @code{sws_flags=@var{flags};}
181 to the filtergraph description.
183 Follows a BNF description for the filtergraph syntax:
185 @var{NAME} ::= sequence of alphanumeric characters and '_'
186 @var{LINKLABEL} ::= "[" @var{NAME} "]"
187 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
188 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
189 @var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
190 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
191 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
194 @section Notes on filtergraph escaping
196 Some filter arguments require the use of special characters, typically
197 @code{:} to separate key=value pairs in a named options list. In this
198 case the user should perform a first level escaping when specifying
199 the filter arguments. For example, consider the following literal
200 string to be embedded in the @ref{drawtext} filter arguments:
202 this is a 'string': may contain one, or more, special characters
205 Since @code{:} is special for the filter arguments syntax, it needs to
206 be escaped, so you get:
208 text=this is a \'string\'\: may contain one, or more, special characters
211 A second level of escaping is required when embedding the filter
212 arguments in a filtergraph description, in order to escape all the
213 filtergraph special characters. Thus the example above becomes:
215 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
218 Finally an additional level of escaping may be needed when writing the
219 filtergraph description in a shell command, which depends on the
220 escaping rules of the adopted shell. For example, assuming that
221 @code{\} is special and needs to be escaped with another @code{\}, the
222 previous string will finally result in:
224 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
227 Sometimes, it might be more convenient to employ quoting in place of
228 escaping. For example the string:
230 Caesar: tu quoque, Brute, fili mi
233 Can be quoted in the filter arguments as:
235 text='Caesar: tu quoque, Brute, fili mi'
238 And finally inserted in a filtergraph like:
240 drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
243 See the @ref{quoting_and_escaping, Quoting and escaping} section for
244 more information about the escaping and quoting rules adopted by
247 @c man end FILTERGRAPH DESCRIPTION
249 @chapter Audio Filters
250 @c man begin AUDIO FILTERS
252 When you configure your FFmpeg build, you can disable any of the
253 existing filters using @code{--disable-filters}.
254 The configure output will show the audio filters included in your
257 Below is a description of the currently available audio filters.
261 Convert the input audio format to the specified formats.
263 The filter accepts a string of the form:
264 "@var{sample_format}:@var{channel_layout}".
266 @var{sample_format} specifies the sample format, and can be a string or the
267 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
268 suffix for a planar sample format.
270 @var{channel_layout} specifies the channel layout, and can be a string
271 or the corresponding number value defined in @file{libavutil/audioconvert.h}.
273 The special parameter "auto", signifies that the filter will
274 automatically select the output format depending on the output filter.
276 Some examples follow.
280 Convert input to float, planar, stereo:
286 Convert input to unsigned 8-bit, automatically select out channel layout:
294 Convert the input audio to one of the specified formats. The framework will
295 negotiate the most appropriate format to minimize conversions.
297 The filter accepts the following named parameters:
301 A comma-separated list of requested sample formats.
304 A comma-separated list of requested sample rates.
306 @item channel_layouts
307 A comma-separated list of requested channel layouts.
311 If a parameter is omitted, all values are allowed.
313 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
315 aformat=sample_fmts\=u8\,s16:channel_layouts\=stereo
320 Merge two or more audio streams into a single multi-channel stream.
322 The filter accepts the following named options:
327 Set the number of inputs. Default is 2.
331 If the channel layouts of the inputs are disjoint, and therefore compatible,
332 the channel layout of the output will be set accordingly and the channels
333 will be reordered as necessary. If the channel layouts of the inputs are not
334 disjoint, the output will have all the channels of the first input then all
335 the channels of the second input, in that order, and the channel layout of
336 the output will be the default value corresponding to the total number of
339 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
340 is FC+BL+BR, then the output will be in 5.1, with the channels in the
341 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
342 first input, b1 is the first channel of the second input).
344 On the other hand, if both input are in stereo, the output channels will be
345 in the default order: a1, a2, b1, b2, and the channel layout will be
346 arbitrarily set to 4.0, which may or may not be the expected value.
348 All inputs must have the same sample rate, and format.
350 If inputs do not have the same duration, the output will stop with the
353 Example: merge two mono files into a stereo stream:
355 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
358 Example: multiple merges:
361 amovie=input.mkv:si=0 [a0];
362 amovie=input.mkv:si=1 [a1];
363 amovie=input.mkv:si=2 [a2];
364 amovie=input.mkv:si=3 [a3];
365 amovie=input.mkv:si=4 [a4];
366 amovie=input.mkv:si=5 [a5];
367 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
372 Mixes multiple audio inputs into a single output.
376 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
378 will mix 3 input audio streams to a single output with the same duration as the
379 first input and a dropout transition time of 3 seconds.
381 The filter accepts the following named parameters:
385 Number of inputs. If unspecified, it defaults to 2.
388 How to determine the end-of-stream.
392 Duration of longest input. (default)
395 Duration of shortest input.
398 Duration of first input.
402 @item dropout_transition
403 Transition time, in seconds, for volume renormalization when an input
404 stream ends. The default value is 2 seconds.
410 Pass the audio source unchanged to the output.
414 Resample the input audio to the specified sample rate.
416 The filter accepts exactly one parameter, the output sample rate. If not
417 specified then the filter will automatically convert between its input
418 and output sample rates.
420 For example, to resample the input audio to 44100Hz:
425 @section asetnsamples
427 Set the number of samples per each output audio frame.
429 The last output packet may contain a different number of samples, as
430 the filter will flush all the remaining samples when the input audio
433 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
438 @item nb_out_samples, n
439 Set the number of frames per each output audio frame. The number is
440 intended as the number of samples @emph{per each channel}.
441 Default value is 1024.
444 If set to 1, the filter will pad the last audio frame with zeroes, so
445 that the last frame will contain the same number of samples as the
446 previous ones. Default value is 1.
449 For example, to set the number of per-frame samples to 1234 and
450 disable padding for the last frame, use:
452 asetnsamples=n=1234:p=0
457 Show a line containing various information for each input audio frame.
458 The input audio is not modified.
460 The shown line contains a sequence of key/value pairs of the form
461 @var{key}:@var{value}.
463 A description of each shown parameter follows:
467 sequential number of the input frame, starting from 0
470 Presentation timestamp of the input frame, in time base units; the time base
471 depends on the filter input pad, and is usually 1/@var{sample_rate}.
474 presentation timestamp of the input frame in seconds
477 position of the frame in the input stream, -1 if this information in
478 unavailable and/or meaningless (for example in case of synthetic audio)
487 sample rate for the audio frame
490 number of samples (per channel) in the frame
493 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
494 the data is treated as if all the planes were concatenated.
496 @item plane_checksums
497 A list of Adler-32 checksums for each data plane.
502 Split input audio into several identical outputs.
504 The filter accepts a single parameter which specifies the number of outputs. If
505 unspecified, it defaults to 2.
509 [in] asplit [out0][out1]
512 will create two separate outputs from the same input.
514 To create 3 or more outputs, you need to specify the number of
517 [in] asplit=3 [out0][out1][out2]
521 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
523 will create 5 copies of the input audio.
528 Forward two audio streams and control the order the buffers are forwarded.
530 The argument to the filter is an expression deciding which stream should be
531 forwarded next: if the result is negative, the first stream is forwarded; if
532 the result is positive or zero, the second stream is forwarded. It can use
533 the following variables:
537 number of buffers forwarded so far on each stream
539 number of samples forwarded so far on each stream
541 current timestamp of each stream
544 The default value is @code{t1-t2}, which means to always forward the stream
545 that has a smaller timestamp.
547 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
548 input, while avoiding too much of a desynchronization:
550 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
551 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
559 The filter accepts exactly one parameter, the audio tempo. If not
560 specified then the filter will assume nominal 1.0 tempo. Tempo must
561 be in the [0.5, 2.0] range.
563 For example, to slow down audio to 80% tempo:
568 For example, to speed up audio to 125% tempo:
575 Make audio easier to listen to on headphones.
577 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
578 so that when listened to on headphones the stereo image is moved from
579 inside your head (standard for headphones) to outside and in front of
580 the listener (standard for speakers).
586 Mix channels with specific gain levels. The filter accepts the output
587 channel layout followed by a set of channels definitions.
589 This filter is also designed to remap efficiently the channels of an audio
592 The filter accepts parameters of the form:
593 "@var{l}:@var{outdef}:@var{outdef}:..."
597 output channel layout or number of channels
600 output channel specification, of the form:
601 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
604 output channel to define, either a channel name (FL, FR, etc.) or a channel
605 number (c0, c1, etc.)
608 multiplicative coefficient for the channel, 1 leaving the volume unchanged
611 input channel to use, see out_name for details; it is not possible to mix
612 named and numbered input channels
615 If the `=' in a channel specification is replaced by `<', then the gains for
616 that specification will be renormalized so that the total is 1, thus
617 avoiding clipping noise.
619 @subsection Mixing examples
621 For example, if you want to down-mix from stereo to mono, but with a bigger
622 factor for the left channel:
624 pan=1:c0=0.9*c0+0.1*c1
627 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
630 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
633 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
634 that should be preferred (see "-ac" option) unless you have very specific
637 @subsection Remapping examples
639 The channel remapping will be effective if, and only if:
642 @item gain coefficients are zeroes or ones,
643 @item only one input per channel output,
646 If all these conditions are satisfied, the filter will notify the user ("Pure
647 channel mapping detected"), and use an optimized and lossless method to do the
650 For example, if you have a 5.1 source and want a stereo audio stream by
651 dropping the extra channels:
653 pan="stereo: c0=FL : c1=FR"
656 Given the same source, you can also switch front left and front right channels
657 and keep the input channel layout:
659 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
662 If the input is a stereo audio stream, you can mute the front left channel (and
663 still keep the stereo channel layout) with:
668 Still with a stereo audio stream input, you can copy the right channel in both
669 front left and right:
671 pan="stereo: c0=FR : c1=FR"
674 @section silencedetect
676 Detect silence in an audio stream.
678 This filter logs a message when it detects that the input audio volume is less
679 or equal to a noise tolerance value for a duration greater or equal to the
680 minimum detected noise duration.
682 The printed times and duration are expressed in seconds.
686 Set silence duration until notification (default is 2 seconds).
689 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
690 specified value) or amplitude ratio. Default is -60dB, or 0.001.
693 Detect 5 seconds of silence with -50dB noise tolerance:
695 silencedetect=n=-50dB:d=5
698 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
699 tolerance in @file{silence.mp3}:
701 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
706 Adjust the input audio volume.
708 The filter accepts exactly one parameter @var{vol}, which expresses
709 how the audio volume will be increased or decreased.
711 Output values are clipped to the maximum value.
713 If @var{vol} is expressed as a decimal number, the output audio
714 volume is given by the relation:
716 @var{output_volume} = @var{vol} * @var{input_volume}
719 If @var{vol} is expressed as a decimal number followed by the string
720 "dB", the value represents the requested change in decibels of the
721 input audio power, and the output audio volume is given by the
724 @var{output_volume} = 10^(@var{vol}/20) * @var{input_volume}
727 Otherwise @var{vol} is considered an expression and its evaluated
728 value is used for computing the output audio volume according to the
731 Default value for @var{vol} is 1.0.
737 Half the input audio volume:
742 The above example is equivalent to:
748 Decrease input audio power by 12 decibels:
754 @section volumedetect
756 Detect the volume of the input video.
758 The filter has no parameters. The input is not modified. Statistics about
759 the volume will be printed in the log when the input stream end is reached.
761 In particular it will show the mean volume (root mean square), maximum
762 volume (on a per-sample basis), and the beginning of an histogram of the
763 registered volume values (from the maximum value to a cumulated 1/1000 of
766 All volumes are in decibels relative to the maximum PCM value.
768 Here is an excerpt of the output:
770 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
771 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
772 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
773 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
774 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
775 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
776 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
777 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
778 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
784 The mean square energy is approximately -27 dB, or 10^-2.7.
786 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
788 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
791 In other words, raising the volume by +4 dB does not cause any clipping,
792 raising it by +5 dB causes clipping for 6 samples, etc.
795 Synchronize audio data with timestamps by squeezing/stretching it and/or
796 dropping samples/adding silence when needed.
798 The filter accepts the following named parameters:
802 Enable stretching/squeezing the data to make it match the timestamps. Disabled
803 by default. When disabled, time gaps are covered with silence.
806 Minimum difference between timestamps and audio data (in seconds) to trigger
807 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
808 this filter, try setting this parameter to 0.
811 Maximum compensation in samples per second. Relevant only with compensate=1.
815 Assume the first pts should be this value.
816 This allows for padding/trimming at the start of stream. By default, no
817 assumption is made about the first frame's expected pts, so no padding or
818 trimming is done. For example, this could be set to 0 to pad the beginning with
819 silence if an audio stream starts after the video stream.
823 @section channelsplit
824 Split each channel in input audio stream into a separate output stream.
826 This filter accepts the following named parameters:
829 Channel layout of the input stream. Default is "stereo".
832 For example, assuming a stereo input MP3 file
834 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
836 will create an output Matroska file with two audio streams, one containing only
837 the left channel and the other the right channel.
839 To split a 5.1 WAV file into per-channel files
841 ffmpeg -i in.wav -filter_complex
842 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
843 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
844 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
849 Remap input channels to new locations.
851 This filter accepts the following named parameters:
854 Channel layout of the output stream.
857 Map channels from input to output. The argument is a comma-separated list of
858 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
859 @var{in_channel} form. @var{in_channel} can be either the name of the input
860 channel (e.g. FL for front left) or its index in the input channel layout.
861 @var{out_channel} is the name of the output channel or its index in the output
862 channel layout. If @var{out_channel} is not given then it is implicitly an
863 index, starting with zero and increasing by one for each mapping.
866 If no mapping is present, the filter will implicitly map input channels to
867 output channels preserving index.
869 For example, assuming a 5.1+downmix input MOV file
871 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
873 will create an output WAV file tagged as stereo from the downmix channels of
876 To fix a 5.1 WAV improperly encoded in AAC's native channel order
878 ffmpeg -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
882 Join multiple input streams into one multi-channel stream.
884 The filter accepts the following named parameters:
888 Number of input streams. Defaults to 2.
891 Desired output channel layout. Defaults to stereo.
894 Map channels from inputs to output. The argument is a comma-separated list of
895 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
896 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
897 can be either the name of the input channel (e.g. FL for front left) or its
898 index in the specified input stream. @var{out_channel} is the name of the output
902 The filter will attempt to guess the mappings when those are not specified
903 explicitly. It does so by first trying to find an unused matching input channel
904 and if that fails it picks the first unused input channel.
906 E.g. to join 3 inputs (with properly set channel layouts)
908 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
911 To build a 5.1 output from 6 single-channel streams:
913 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
914 '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'
919 Convert the audio sample format, sample rate and channel layout. This filter is
920 not meant to be used directly.
922 @c man end AUDIO FILTERS
924 @chapter Audio Sources
925 @c man begin AUDIO SOURCES
927 Below is a description of the currently available audio sources.
931 Buffer audio frames, and make them available to the filter chain.
933 This source is mainly intended for a programmatic use, in particular
934 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
936 It accepts the following mandatory parameters:
937 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
942 The sample rate of the incoming audio buffers.
945 The sample format of the incoming audio buffers.
946 Either a sample format name or its corresponging integer representation from
947 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
950 The channel layout of the incoming audio buffers.
951 Either a channel layout name from channel_layout_map in
952 @file{libavutil/audioconvert.c} or its corresponding integer representation
953 from the AV_CH_LAYOUT_* macros in @file{libavutil/audioconvert.h}
959 abuffer=44100:s16p:stereo
962 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
963 Since the sample format with name "s16p" corresponds to the number
964 6 and the "stereo" channel layout corresponds to the value 0x3, this is
972 Generate an audio signal specified by an expression.
974 This source accepts in input one or more expressions (one for each
975 channel), which are evaluated and used to generate a corresponding
978 It accepts the syntax: @var{exprs}[::@var{options}].
979 @var{exprs} is a list of expressions separated by ":", one for each
980 separate channel. In case the @var{channel_layout} is not
981 specified, the selected channel layout depends on the number of
982 provided expressions.
984 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
987 The description of the accepted options follows.
991 @item channel_layout, c
992 Set the channel layout. The number of channels in the specified layout
993 must be equal to the number of specified expressions.
996 Set the minimum duration of the sourced audio. See the function
997 @code{av_parse_time()} for the accepted format.
998 Note that the resulting duration may be greater than the specified
999 duration, as the generated audio is always cut at the end of a
1002 If not specified, or the expressed duration is negative, the audio is
1003 supposed to be generated forever.
1006 Set the number of samples per channel per each output frame,
1009 @item sample_rate, s
1010 Specify the sample rate, default to 44100.
1013 Each expression in @var{exprs} can contain the following constants:
1017 number of the evaluated sample, starting from 0
1020 time of the evaluated sample expressed in seconds, starting from 0
1027 @subsection Examples
1039 Generate a sin signal with frequency of 440 Hz, set sample rate to
1042 aevalsrc="sin(440*2*PI*t)::s=8000"
1046 Generate a two channels signal, specify the channel layout (Front
1047 Center + Back Center) explicitly:
1049 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1053 Generate white noise:
1055 aevalsrc="-2+random(0)"
1059 Generate an amplitude modulated signal:
1061 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1065 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1067 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1074 Null audio source, return unprocessed audio frames. It is mainly useful
1075 as a template and to be employed in analysis / debugging tools, or as
1076 the source for filters which ignore the input data (for example the sox
1079 It accepts an optional sequence of @var{key}=@var{value} pairs,
1082 The description of the accepted options follows.
1086 @item sample_rate, s
1087 Specify the sample rate, and defaults to 44100.
1089 @item channel_layout, cl
1091 Specify the channel layout, and can be either an integer or a string
1092 representing a channel layout. The default value of @var{channel_layout}
1095 Check the channel_layout_map definition in
1096 @file{libavcodec/audioconvert.c} for the mapping between strings and
1097 channel layout values.
1100 Set the number of samples per requested frames.
1104 Follow some examples:
1106 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1107 anullsrc=r=48000:cl=4
1110 anullsrc=r=48000:cl=mono
1114 Buffer audio frames, and make them available to the filter chain.
1116 This source is not intended to be part of user-supplied graph descriptions but
1117 for insertion by calling programs through the interface defined in
1118 @file{libavfilter/buffersrc.h}.
1120 It accepts the following named parameters:
1124 Timebase which will be used for timestamps of submitted frames. It must be
1125 either a floating-point number or in @var{numerator}/@var{denominator} form.
1131 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1133 @item channel_layout
1134 Channel layout of the audio data, in the form that can be accepted by
1135 @code{av_get_channel_layout()}.
1138 All the parameters need to be explicitly defined.
1142 Synthesize a voice utterance using the libflite library.
1144 To enable compilation of this filter you need to configure FFmpeg with
1145 @code{--enable-libflite}.
1147 Note that the flite library is not thread-safe.
1149 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1152 The description of the accepted parameters follows.
1157 If set to 1, list the names of the available voices and exit
1158 immediately. Default value is 0.
1161 Set the maximum number of samples per frame. Default value is 512.
1164 Set the filename containing the text to speak.
1167 Set the text to speak.
1170 Set the voice to use for the speech synthesis. Default value is
1171 @code{kal}. See also the @var{list_voices} option.
1174 @subsection Examples
1178 Read from file @file{speech.txt}, and synthetize the text using the
1179 standard flite voice:
1181 flite=textfile=speech.txt
1185 Read the specified text selecting the @code{slt} voice:
1187 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1191 Input text to ffmpeg:
1193 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1197 Make @file{ffplay} speak the specified text, using @code{flite} and
1198 the @code{lavfi} device:
1200 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1204 For more information about libflite, check:
1205 @url{http://www.speech.cs.cmu.edu/flite/}
1207 @c man end AUDIO SOURCES
1209 @chapter Audio Sinks
1210 @c man begin AUDIO SINKS
1212 Below is a description of the currently available audio sinks.
1214 @section abuffersink
1216 Buffer audio frames, and make them available to the end of filter chain.
1218 This sink is mainly intended for programmatic use, in particular
1219 through the interface defined in @file{libavfilter/buffersink.h}.
1221 It requires a pointer to an AVABufferSinkContext structure, which
1222 defines the incoming buffers' formats, to be passed as the opaque
1223 parameter to @code{avfilter_init_filter} for initialization.
1227 Null audio sink, do absolutely nothing with the input audio. It is
1228 mainly useful as a template and to be employed in analysis / debugging
1231 @section abuffersink
1232 This sink is intended for programmatic use. Frames that arrive on this sink can
1233 be retrieved by the calling program using the interface defined in
1234 @file{libavfilter/buffersink.h}.
1236 This filter accepts no parameters.
1238 @c man end AUDIO SINKS
1240 @chapter Video Filters
1241 @c man begin VIDEO FILTERS
1243 When you configure your FFmpeg build, you can disable any of the
1244 existing filters using @code{--disable-filters}.
1245 The configure output will show the video filters included in your
1248 Below is a description of the currently available video filters.
1250 @section alphaextract
1252 Extract the alpha component from the input as a grayscale video. This
1253 is especially useful with the @var{alphamerge} filter.
1257 Add or replace the alpha component of the primary input with the
1258 grayscale value of a second input. This is intended for use with
1259 @var{alphaextract} to allow the transmission or storage of frame
1260 sequences that have alpha in a format that doesn't support an alpha
1263 For example, to reconstruct full frames from a normal YUV-encoded video
1264 and a separate video created with @var{alphaextract}, you might use:
1266 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1269 Since this filter is designed for reconstruction, it operates on frame
1270 sequences without considering timestamps, and terminates when either
1271 input reaches end of stream. This will cause problems if your encoding
1272 pipeline drops frames. If you're trying to apply an image as an
1273 overlay to a video stream, consider the @var{overlay} filter instead.
1277 Draw ASS (Advanced Substation Alpha) subtitles on top of input video
1278 using the libass library.
1280 To enable compilation of this filter you need to configure FFmpeg with
1281 @code{--enable-libass}.
1283 This filter accepts the following named options, expressed as a
1284 sequence of @var{key}=@var{value} pairs, separated by ":".
1288 Set the filename of the ASS file to read. It must be specified.
1291 Specify the size of the original video, the video for which the ASS file
1292 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
1293 necessary to correctly scale the fonts if the aspect ratio has been changed.
1296 If the first key is not specified, it is assumed that the first value
1297 specifies the @option{filename}.
1299 For example, to render the file @file{sub.ass} on top of the input
1300 video, use the command:
1305 which is equivalent to:
1307 ass=filename=sub.ass
1312 Compute the bounding box for the non-black pixels in the input frame
1315 This filter computes the bounding box containing all the pixels with a
1316 luminance value greater than the minimum allowed value.
1317 The parameters describing the bounding box are printed on the filter
1320 @section blackdetect
1322 Detect video intervals that are (almost) completely black. Can be
1323 useful to detect chapter transitions, commercials, or invalid
1324 recordings. Output lines contains the time for the start, end and
1325 duration of the detected black interval expressed in seconds.
1327 In order to display the output lines, you need to set the loglevel at
1328 least to the AV_LOG_INFO value.
1330 This filter accepts a list of options in the form of
1331 @var{key}=@var{value} pairs separated by ":". A description of the
1332 accepted options follows.
1335 @item black_min_duration, d
1336 Set the minimum detected black duration expressed in seconds. It must
1337 be a non-negative floating point number.
1339 Default value is 2.0.
1341 @item picture_black_ratio_th, pic_th
1342 Set the threshold for considering a picture "black".
1343 Express the minimum value for the ratio:
1345 @var{nb_black_pixels} / @var{nb_pixels}
1348 for which a picture is considered black.
1349 Default value is 0.98.
1351 @item pixel_black_th, pix_th
1352 Set the threshold for considering a pixel "black".
1354 The threshold expresses the maximum pixel luminance value for which a
1355 pixel is considered "black". The provided value is scaled according to
1356 the following equation:
1358 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1361 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1362 the input video format, the range is [0-255] for YUV full-range
1363 formats and [16-235] for YUV non full-range formats.
1365 Default value is 0.10.
1368 The following example sets the maximum pixel threshold to the minimum
1369 value, and detects only black intervals of 2 or more seconds:
1371 blackdetect=d=2:pix_th=0.00
1376 Detect frames that are (almost) completely black. Can be useful to
1377 detect chapter transitions or commercials. Output lines consist of
1378 the frame number of the detected frame, the percentage of blackness,
1379 the position in the file if known or -1 and the timestamp in seconds.
1381 In order to display the output lines, you need to set the loglevel at
1382 least to the AV_LOG_INFO value.
1384 The filter accepts the syntax:
1386 blackframe[=@var{amount}:[@var{threshold}]]
1389 @var{amount} is the percentage of the pixels that have to be below the
1390 threshold, and defaults to 98.
1392 @var{threshold} is the threshold below which a pixel value is
1393 considered black, and defaults to 32.
1397 Apply boxblur algorithm to the input video.
1399 This filter accepts the parameters:
1400 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
1402 Chroma and alpha parameters are optional, if not specified they default
1403 to the corresponding values set for @var{luma_radius} and
1406 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
1407 the radius in pixels of the box used for blurring the corresponding
1408 input plane. They are expressions, and can contain the following
1412 the input width and height in pixels
1415 the input chroma image width and height in pixels
1418 horizontal and vertical chroma subsample values. For example for the
1419 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1422 The radius must be a non-negative number, and must not be greater than
1423 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
1424 and of @code{min(cw,ch)/2} for the chroma planes.
1426 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
1427 how many times the boxblur filter is applied to the corresponding
1430 Some examples follow:
1435 Apply a boxblur filter with luma, chroma, and alpha radius
1442 Set luma radius to 2, alpha and chroma radius to 0
1448 Set luma and chroma radius to a fraction of the video dimension
1450 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
1455 @section colormatrix
1457 The colormatrix filter allows conversion between any of the following color
1458 space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m})
1459 and FCC (@var{fcc}).
1461 The syntax of the parameters is @var{source}:@var{destination}:
1464 colormatrix=bt601:smpte240m
1469 Copy the input source unchanged to the output. Mainly useful for
1474 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}
1476 The @var{keep_aspect} parameter is optional, if specified and set to a
1477 non-zero value will force the output display aspect ratio to be the
1478 same of the input, by changing the output sample aspect ratio.
1480 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
1481 expressions containing the following constants:
1485 the computed values for @var{x} and @var{y}. They are evaluated for
1489 the input width and height
1492 same as @var{in_w} and @var{in_h}
1495 the output (cropped) width and height
1498 same as @var{out_w} and @var{out_h}
1501 same as @var{iw} / @var{ih}
1504 input sample aspect ratio
1507 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1510 horizontal and vertical chroma subsample values. For example for the
1511 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1514 the number of input frame, starting from 0
1517 the position in the file of the input frame, NAN if unknown
1520 timestamp expressed in seconds, NAN if the input timestamp is unknown
1524 The @var{out_w} and @var{out_h} parameters specify the expressions for
1525 the width and height of the output (cropped) video. They are
1526 evaluated just at the configuration of the filter.
1528 The default value of @var{out_w} is "in_w", and the default value of
1529 @var{out_h} is "in_h".
1531 The expression for @var{out_w} may depend on the value of @var{out_h},
1532 and the expression for @var{out_h} may depend on @var{out_w}, but they
1533 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
1534 evaluated after @var{out_w} and @var{out_h}.
1536 The @var{x} and @var{y} parameters specify the expressions for the
1537 position of the top-left corner of the output (non-cropped) area. They
1538 are evaluated for each frame. If the evaluated value is not valid, it
1539 is approximated to the nearest valid value.
1541 The default value of @var{x} is "(in_w-out_w)/2", and the default
1542 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
1543 the center of the input image.
1545 The expression for @var{x} may depend on @var{y}, and the expression
1546 for @var{y} may depend on @var{x}.
1548 Follow some examples:
1550 # crop the central input area with size 100x100
1553 # crop the central input area with size 2/3 of the input video
1554 "crop=2/3*in_w:2/3*in_h"
1556 # crop the input video central square
1559 # delimit the rectangle with the top-left corner placed at position
1560 # 100:100 and the right-bottom corner corresponding to the right-bottom
1561 # corner of the input image.
1562 crop=in_w-100:in_h-100:100:100
1564 # crop 10 pixels from the left and right borders, and 20 pixels from
1565 # the top and bottom borders
1566 "crop=in_w-2*10:in_h-2*20"
1568 # keep only the bottom right quarter of the input image
1569 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
1571 # crop height for getting Greek harmony
1572 "crop=in_w:1/PHI*in_w"
1575 "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)"
1577 # erratic camera effect depending on timestamp
1578 "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)"
1580 # set x depending on the value of y
1581 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
1586 Auto-detect crop size.
1588 Calculate necessary cropping parameters and prints the recommended
1589 parameters through the logging system. The detected dimensions
1590 correspond to the non-black area of the input video.
1592 It accepts the syntax:
1594 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
1600 Threshold, which can be optionally specified from nothing (0) to
1601 everything (255), defaults to 24.
1604 Value which the width/height should be divisible by, defaults to
1605 16. The offset is automatically adjusted to center the video. Use 2 to
1606 get only even dimensions (needed for 4:2:2 video). 16 is best when
1607 encoding to most video codecs.
1610 Counter that determines after how many frames cropdetect will reset
1611 the previously detected largest video area and start over to detect
1612 the current optimal crop area. Defaults to 0.
1614 This can be useful when channel logos distort the video area. 0
1615 indicates never reset and return the largest area encountered during
1621 This filter drops frames that do not differ greatly from the previous
1622 frame in order to reduce framerate. The main use of this filter is
1623 for very-low-bitrate encoding (e.g. streaming over dialup modem), but
1624 it could in theory be used for fixing movies that were
1625 inverse-telecined incorrectly.
1627 It accepts the following parameters:
1628 @var{max}:@var{hi}:@var{lo}:@var{frac}.
1633 Set the maximum number of consecutive frames which can be dropped (if
1634 positive), or the minimum interval between dropped frames (if
1635 negative). If the value is 0, the frame is dropped unregarding the
1636 number of previous sequentially dropped frames.
1641 Set the dropping threshold values.
1643 Values for @var{hi} and @var{lo} are for 8x8 pixel blocks and
1644 represent actual pixel value differences, so a threshold of 64
1645 corresponds to 1 unit of difference for each pixel, or the same spread
1646 out differently over the block.
1648 A frame is a candidate for dropping if no 8x8 blocks differ by more
1649 than a threshold of @var{hi}, and if no more than @var{frac} blocks (1
1650 meaning the whole image) differ by more than a threshold of @var{lo}.
1652 Default value for @var{hi} is 64*12, default value for @var{lo} is
1653 64*5, and default value for @var{frac} is 0.33.
1658 Suppress a TV station logo by a simple interpolation of the surrounding
1659 pixels. Just set a rectangle covering the logo and watch it disappear
1660 (and sometimes something even uglier appear - your mileage may vary).
1662 The filter accepts parameters as a string of the form
1663 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
1664 @var{key}=@var{value} pairs, separated by ":".
1666 The description of the accepted parameters follows.
1671 Specify the top left corner coordinates of the logo. They must be
1675 Specify the width and height of the logo to clear. They must be
1679 Specify the thickness of the fuzzy edge of the rectangle (added to
1680 @var{w} and @var{h}). The default value is 4.
1683 When set to 1, a green rectangle is drawn on the screen to simplify
1684 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1685 @var{band} is set to 4. The default value is 0.
1689 Some examples follow.
1694 Set a rectangle covering the area with top left corner coordinates 0,0
1695 and size 100x77, setting a band of size 10:
1697 delogo=0:0:100:77:10
1701 As the previous example, but use named options:
1703 delogo=x=0:y=0:w=100:h=77:band=10
1710 Attempt to fix small changes in horizontal and/or vertical shift. This
1711 filter helps remove camera shake from hand-holding a camera, bumping a
1712 tripod, moving on a vehicle, etc.
1714 The filter accepts parameters as a string of the form
1715 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
1717 A description of the accepted parameters follows.
1722 Specify a rectangular area where to limit the search for motion
1724 If desired the search for motion vectors can be limited to a
1725 rectangular area of the frame defined by its top left corner, width
1726 and height. These parameters have the same meaning as the drawbox
1727 filter which can be used to visualise the position of the bounding
1730 This is useful when simultaneous movement of subjects within the frame
1731 might be confused for camera motion by the motion vector search.
1733 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
1734 then the full frame is used. This allows later options to be set
1735 without specifying the bounding box for the motion vector search.
1737 Default - search the whole frame.
1740 Specify the maximum extent of movement in x and y directions in the
1741 range 0-64 pixels. Default 16.
1744 Specify how to generate pixels to fill blanks at the edge of the
1745 frame. An integer from 0 to 3 as follows:
1748 Fill zeroes at blank locations
1750 Original image at blank locations
1752 Extruded edge value at blank locations
1754 Mirrored edge at blank locations
1757 The default setting is mirror edge at blank locations.
1760 Specify the blocksize to use for motion search. Range 4-128 pixels,
1764 Specify the contrast threshold for blocks. Only blocks with more than
1765 the specified contrast (difference between darkest and lightest
1766 pixels) will be considered. Range 1-255, default 125.
1769 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
1770 search. Default - exhaustive search.
1773 If set then a detailed log of the motion search is written to the
1780 Draw a colored box on the input image.
1782 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1785 The description of the accepted parameters follows.
1789 Specify the top left corner coordinates of the box. Default to 0.
1793 Specify the width and height of the box, if 0 they are interpreted as
1794 the input width and height. Default to 0.
1797 Specify the color of the box to write, it can be the name of a color
1798 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
1799 value @code{invert} is used, the box edge color is the same as the
1800 video with inverted luma.
1803 Set the thickness of the box edge. Default value is @code{4}.
1806 If the key of the first options is omitted, the arguments are
1807 interpreted according to the following syntax:
1809 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}:@var{thickness}
1812 Some examples follow:
1815 Draw a black box around the edge of the input image:
1821 Draw a box with color red and an opacity of 50%:
1823 drawbox=10:20:200:60:red@@0.5
1826 The previous example can be specified as:
1828 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
1832 Fill the box with pink color:
1834 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
1841 Draw text string or text from specified file on top of video using the
1842 libfreetype library.
1844 To enable compilation of this filter you need to configure FFmpeg with
1845 @code{--enable-libfreetype}.
1847 The filter also recognizes strftime() sequences in the provided text
1848 and expands them accordingly. Check the documentation of strftime().
1850 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1853 The description of the accepted parameters follows.
1858 Used to draw a box around text using background color.
1859 Value should be either 1 (enable) or 0 (disable).
1860 The default value of @var{box} is 0.
1863 The color to be used for drawing box around text.
1864 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1865 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1866 The default value of @var{boxcolor} is "white".
1869 Set an expression which specifies if the text should be drawn. If the
1870 expression evaluates to 0, the text is not drawn. This is useful for
1871 specifying that the text should be drawn only when specific conditions
1874 Default value is "1".
1876 See below for the list of accepted constants and functions.
1879 If true, check and fix text coords to avoid clipping.
1882 The color to be used for drawing fonts.
1883 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1884 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1885 The default value of @var{fontcolor} is "black".
1888 The font file to be used for drawing text. Path must be included.
1889 This parameter is mandatory.
1892 The font size to be used for drawing text.
1893 The default value of @var{fontsize} is 16.
1896 Flags to be used for loading the fonts.
1898 The flags map the corresponding flags supported by libfreetype, and are
1899 a combination of the following values:
1906 @item vertical_layout
1907 @item force_autohint
1910 @item ignore_global_advance_width
1912 @item ignore_transform
1919 Default value is "render".
1921 For more information consult the documentation for the FT_LOAD_*
1925 The color to be used for drawing a shadow behind the drawn text. It
1926 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1927 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1928 The default value of @var{shadowcolor} is "black".
1930 @item shadowx, shadowy
1931 The x and y offsets for the text shadow position with respect to the
1932 position of the text. They can be either positive or negative
1933 values. Default value for both is "0".
1936 The size in number of spaces to use for rendering the tab.
1940 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
1941 format. It can be used with or without text parameter. @var{timecode_rate}
1942 option must be specified.
1944 @item timecode_rate, rate, r
1945 Set the timecode frame rate (timecode only).
1948 The text string to be drawn. The text must be a sequence of UTF-8
1950 This parameter is mandatory if no file is specified with the parameter
1954 A text file containing text to be drawn. The text must be a sequence
1955 of UTF-8 encoded characters.
1957 This parameter is mandatory if no text string is specified with the
1958 parameter @var{text}.
1960 If both @var{text} and @var{textfile} are specified, an error is thrown.
1963 The expressions which specify the offsets where text will be drawn
1964 within the video frame. They are relative to the top/left border of the
1967 The default value of @var{x} and @var{y} is "0".
1969 See below for the list of accepted constants and functions.
1972 The parameters for @var{x} and @var{y} are expressions containing the
1973 following constants and functions:
1977 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
1980 horizontal and vertical chroma subsample values. For example for the
1981 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1984 the height of each text line
1992 @item max_glyph_a, ascent
1993 the maximum distance from the baseline to the highest/upper grid
1994 coordinate used to place a glyph outline point, for all the rendered
1996 It is a positive value, due to the grid's orientation with the Y axis
1999 @item max_glyph_d, descent
2000 the maximum distance from the baseline to the lowest grid coordinate
2001 used to place a glyph outline point, for all the rendered glyphs.
2002 This is a negative value, due to the grid's orientation, with the Y axis
2006 maximum glyph height, that is the maximum height for all the glyphs
2007 contained in the rendered text, it is equivalent to @var{ascent} -
2011 maximum glyph width, that is the maximum width for all the glyphs
2012 contained in the rendered text
2015 the number of input frame, starting from 0
2017 @item rand(min, max)
2018 return a random number included between @var{min} and @var{max}
2021 input sample aspect ratio
2024 timestamp expressed in seconds, NAN if the input timestamp is unknown
2027 the height of the rendered text
2030 the width of the rendered text
2033 the x and y offset coordinates where the text is drawn.
2035 These parameters allow the @var{x} and @var{y} expressions to refer
2036 each other, so you can for example specify @code{y=x/dar}.
2039 If libavfilter was built with @code{--enable-fontconfig}, then
2040 @option{fontfile} can be a fontconfig pattern or omitted.
2042 Some examples follow.
2047 Draw "Test Text" with font FreeSerif, using the default values for the
2048 optional parameters.
2051 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2055 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2056 and y=50 (counting from the top-left corner of the screen), text is
2057 yellow with a red box around it. Both the text and the box have an
2061 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2062 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2065 Note that the double quotes are not necessary if spaces are not used
2066 within the parameter list.
2069 Show the text at the center of the video frame:
2071 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2075 Show a text line sliding from right to left in the last row of the video
2076 frame. The file @file{LONG_LINE} is assumed to contain a single line
2079 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2083 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2085 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2089 Draw a single green letter "g", at the center of the input video.
2090 The glyph baseline is placed at half screen height.
2092 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2096 Show text for 1 second every 3 seconds:
2098 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2102 Use fontconfig to set the font. Note that the colons need to be escaped.
2104 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2109 For more information about libfreetype, check:
2110 @url{http://www.freetype.org/}.
2112 For more information about fontconfig, check:
2113 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
2117 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
2119 This filter accepts the following optional named parameters:
2123 Set low and high threshold values used by the Canny thresholding
2126 The high threshold selects the "strong" edge pixels, which are then
2127 connected through 8-connectivity with the "weak" edge pixels selected
2128 by the low threshold.
2130 @var{low} and @var{high} threshold values must be choosen in the range
2131 [0,1], and @var{low} should be lesser or equal to @var{high}.
2133 Default value for @var{low} is @code{20/255}, and default value for @var{high}
2139 edgedetect=low=0.1:high=0.4
2144 Apply fade-in/out effect to input video.
2146 It accepts the parameters:
2147 @var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}]
2149 @var{type} specifies if the effect type, can be either "in" for
2150 fade-in, or "out" for a fade-out effect.
2152 @var{start_frame} specifies the number of the start frame for starting
2153 to apply the fade effect.
2155 @var{nb_frames} specifies the number of frames for which the fade
2156 effect has to last. At the end of the fade-in effect the output video
2157 will have the same intensity as the input video, at the end of the
2158 fade-out transition the output video will be completely black.
2160 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
2161 separated by ":". The description of the accepted options follows.
2168 @item start_frame, s
2169 See @var{start_frame}.
2172 See @var{nb_frames}.
2175 If set to 1, fade only alpha channel, if one exists on the input.
2179 A few usage examples follow, usable too as test scenarios.
2181 # fade in first 30 frames of video
2184 # fade out last 45 frames of a 200-frame video
2187 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
2188 fade=in:0:25, fade=out:975:25
2190 # make first 5 frames black, then fade in from frame 5-24
2193 # fade in alpha over first 25 frames of video
2194 fade=in:0:25:alpha=1
2199 Extract a single field from an interlaced image using stride
2200 arithmetic to avoid wasting CPU time. The output frames are marked as
2203 This filter accepts the following named options:
2206 Specify whether to extract the top (if the value is @code{0} or
2207 @code{top}) or the bottom field (if the value is @code{1} or
2211 If the option key is not specified, the first value sets the @var{type}
2212 option. For example:
2224 Transform the field order of the input video.
2226 It accepts one parameter which specifies the required field order that
2227 the input interlaced video will be transformed to. The parameter can
2228 assume one of the following values:
2232 output bottom field first
2234 output top field first
2237 Default value is "tff".
2239 Transformation is achieved by shifting the picture content up or down
2240 by one line, and filling the remaining line with appropriate picture content.
2241 This method is consistent with most broadcast field order converters.
2243 If the input video is not flagged as being interlaced, or it is already
2244 flagged as being of the required output field order then this filter does
2245 not alter the incoming video.
2247 This filter is very useful when converting to or from PAL DV material,
2248 which is bottom field first.
2252 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
2257 Buffer input images and send them when they are requested.
2259 This filter is mainly useful when auto-inserted by the libavfilter
2262 The filter does not take parameters.
2266 Convert the input video to one of the specified pixel formats.
2267 Libavfilter will try to pick one that is supported for the input to
2270 The filter accepts a list of pixel format names, separated by ":",
2271 for example "yuv420p:monow:rgb24".
2273 Some examples follow:
2275 # convert the input video to the format "yuv420p"
2278 # convert the input video to any of the formats in the list
2279 format=yuv420p:yuv444p:yuv410p
2284 Convert the video to specified constant framerate by duplicating or dropping
2285 frames as necessary.
2287 This filter accepts the following named parameters:
2291 Desired output framerate.
2294 Rounding method. The default is @code{near}.
2300 Select one frame every N.
2302 This filter accepts in input a string representing a positive
2303 integer. Default argument is @code{1}.
2308 Apply a frei0r effect to the input video.
2310 To enable compilation of this filter you need to install the frei0r
2311 header and configure FFmpeg with @code{--enable-frei0r}.
2313 The filter supports the syntax:
2315 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
2318 @var{filter_name} is the name to the frei0r effect to load. If the
2319 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
2320 is searched in each one of the directories specified by the colon (or
2321 semicolon on Windows platforms) separated list in @env{FREIOR_PATH},
2322 otherwise in the standard frei0r paths, which are in this order:
2323 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
2324 @file{/usr/lib/frei0r-1/}.
2326 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
2327 for the frei0r effect.
2329 A frei0r effect parameter can be a boolean (whose values are specified
2330 with "y" and "n"), a double, a color (specified by the syntax
2331 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
2332 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
2333 description), a position (specified by the syntax @var{X}/@var{Y},
2334 @var{X} and @var{Y} being float numbers) and a string.
2336 The number and kind of parameters depend on the loaded effect. If an
2337 effect parameter is not specified the default value is set.
2339 Some examples follow:
2343 Apply the distort0r effect, set the first two double parameters:
2345 frei0r=distort0r:0.5:0.01
2349 Apply the colordistance effect, takes a color as first parameter:
2351 frei0r=colordistance:0.2/0.3/0.4
2352 frei0r=colordistance:violet
2353 frei0r=colordistance:0x112233
2357 Apply the perspective effect, specify the top left and top right image
2360 frei0r=perspective:0.2/0.2:0.8/0.2
2364 For more information see:
2365 @url{http://frei0r.dyne.org}
2369 The filter takes one, two or three equations as parameter, separated by ':'.
2370 The first equation is mandatory and applies to the luma plane. The two
2371 following are respectively for chroma blue and chroma red planes.
2373 The filter syntax allows named parameters:
2377 the luminance expression
2379 the chrominance blue expression
2381 the chrominance red expression
2384 If one of the chrominance expression is not defined, it falls back on the other
2385 one. If none of them are specified, they will evaluate the luminance
2388 The expressions can use the following variables and functions:
2392 The sequential number of the filtered frame, starting from @code{0}.
2395 The coordinates of the current sample.
2398 The width and height of the image.
2401 Width and height scale depending on the currently filtered plane. It is the
2402 ratio between the corresponding luma plane number of pixels and the current
2403 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2404 @code{0.5,0.5} for chroma planes.
2407 Return the value of the pixel at location (@var{x},@var{y}) of the current
2411 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
2415 Return the value of the pixel at location (@var{x},@var{y}) of the
2416 blue-difference chroma plane.
2419 Return the value of the pixel at location (@var{x},@var{y}) of the
2420 red-difference chroma plane.
2423 For functions, if @var{x} and @var{y} are outside the area, the value will be
2424 automatically clipped to the closer edge.
2426 Some examples follow:
2430 Flip the image horizontally:
2436 Generate a fancy enigmatic moving light:
2438 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
2444 Fix the banding artifacts that are sometimes introduced into nearly flat
2445 regions by truncation to 8bit color depth.
2446 Interpolate the gradients that should go where the bands are, and
2449 This filter is designed for playback only. Do not use it prior to
2450 lossy compression, because compression tends to lose the dither and
2451 bring back the bands.
2453 The filter takes two optional parameters, separated by ':':
2454 @var{strength}:@var{radius}
2456 @var{strength} is the maximum amount by which the filter will change
2457 any one pixel. Also the threshold for detecting nearly flat
2458 regions. Acceptable values range from .51 to 255, default value is
2459 1.2, out-of-range values will be clipped to the valid range.
2461 @var{radius} is the neighborhood to fit the gradient to. A larger
2462 radius makes for smoother gradients, but also prevents the filter from
2463 modifying the pixels near detailed regions. Acceptable values are
2464 8-32, default value is 16, out-of-range values will be clipped to the
2468 # default parameters
2477 Flip the input video horizontally.
2479 For example to horizontally flip the input video with @command{ffmpeg}:
2481 ffmpeg -i in.avi -vf "hflip" out.avi
2486 High precision/quality 3d denoise filter. This filter aims to reduce
2487 image noise producing smooth images and making still images really
2488 still. It should enhance compressibility.
2490 It accepts the following optional parameters:
2491 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
2495 a non-negative float number which specifies spatial luma strength,
2498 @item chroma_spatial
2499 a non-negative float number which specifies spatial chroma strength,
2500 defaults to 3.0*@var{luma_spatial}/4.0
2503 a float number which specifies luma temporal strength, defaults to
2504 6.0*@var{luma_spatial}/4.0
2507 a float number which specifies chroma temporal strength, defaults to
2508 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
2513 Modify the hue and/or the saturation of the input.
2515 This filter accepts the following optional named options:
2519 Specify the hue angle as a number of degrees. It accepts a float
2520 number or an expression, and defaults to 0.0.
2523 Specify the hue angle as a number of degrees. It accepts a float
2524 number or an expression, and defaults to 0.0.
2527 Specify the saturation in the [-10,10] range. It accepts a float number and
2531 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
2532 following constants:
2536 frame count of the input frame starting from 0
2539 presentation timestamp of the input frame expressed in time base units
2542 frame rate of the input video, NAN if the input frame rate is unknown
2545 timestamp expressed in seconds, NAN if the input timestamp is unknown
2548 time base of the input video
2551 The options can also be set using the syntax: @var{hue}:@var{saturation}
2553 In this case @var{hue} is expressed in degrees.
2555 Some examples follow:
2558 Set the hue to 90 degrees and the saturation to 1.0:
2564 Same command but expressing the hue in radians:
2570 Same command without named options, hue must be expressed in degrees:
2576 Note that "h:s" syntax does not support expressions for the values of
2577 h and s, so the following example will issue an error:
2583 Rotate hue and make the saturation swing between 0
2584 and 2 over a period of 1 second:
2586 hue="H=2*PI*t: s=sin(2*PI*t)+1"
2590 Apply a 3 seconds saturation fade-in effect starting at 0:
2595 The general fade-in expression can be written as:
2597 hue="s=min(0\, max((t-START)/DURATION\, 1))"
2601 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
2603 hue="s=max(0\, min(1\, (8-t)/3))"
2606 The general fade-out expression can be written as:
2608 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
2613 @subsection Commands
2615 This filter supports the following command:
2618 Modify the hue and/or the saturation of the input video.
2619 The command accepts the same named options and syntax than when calling the
2620 filter from the command-line.
2622 If a parameter is omitted, it is kept at its current value.
2627 Interlaceing detect filter. This filter tries to detect if the input is
2628 interlaced or progressive. Top or bottom field first.
2630 @section lut, lutrgb, lutyuv
2632 Compute a look-up table for binding each pixel component input value
2633 to an output value, and apply it to input video.
2635 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
2636 to an RGB input video.
2638 These filters accept in input a ":"-separated list of options, which
2639 specify the expressions used for computing the lookup table for the
2640 corresponding pixel component values.
2642 The @var{lut} filter requires either YUV or RGB pixel formats in
2643 input, and accepts the options:
2645 @item @var{c0} (first pixel component)
2646 @item @var{c1} (second pixel component)
2647 @item @var{c2} (third pixel component)
2648 @item @var{c3} (fourth pixel component, corresponds to the alpha component)
2651 The exact component associated to each option depends on the format in
2654 The @var{lutrgb} filter requires RGB pixel formats in input, and
2655 accepts the options:
2657 @item @var{r} (red component)
2658 @item @var{g} (green component)
2659 @item @var{b} (blue component)
2660 @item @var{a} (alpha component)
2663 The @var{lutyuv} filter requires YUV pixel formats in input, and
2664 accepts the options:
2666 @item @var{y} (Y/luminance component)
2667 @item @var{u} (U/Cb component)
2668 @item @var{v} (V/Cr component)
2669 @item @var{a} (alpha component)
2672 The expressions can contain the following constants and functions:
2676 the input width and height
2679 input value for the pixel component
2682 the input value clipped in the @var{minval}-@var{maxval} range
2685 maximum value for the pixel component
2688 minimum value for the pixel component
2691 the negated value for the pixel component value clipped in the
2692 @var{minval}-@var{maxval} range , it corresponds to the expression
2693 "maxval-clipval+minval"
2696 the computed value in @var{val} clipped in the
2697 @var{minval}-@var{maxval} range
2699 @item gammaval(gamma)
2700 the computed gamma correction value of the pixel component value
2701 clipped in the @var{minval}-@var{maxval} range, corresponds to the
2703 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
2707 All expressions default to "val".
2709 Some examples follow:
2711 # negate input video
2712 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
2713 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
2715 # the above is the same as
2716 lutrgb="r=negval:g=negval:b=negval"
2717 lutyuv="y=negval:u=negval:v=negval"
2722 # remove chroma components, turns the video into a graytone image
2723 lutyuv="u=128:v=128"
2725 # apply a luma burning effect
2728 # remove green and blue components
2731 # set a constant alpha channel value on input
2732 format=rgba,lutrgb=a="maxval-minval/2"
2734 # correct luminance gamma by a 0.5 factor
2735 lutyuv=y=gammaval(0.5)
2740 Apply an MPlayer filter to the input video.
2742 This filter provides a wrapper around most of the filters of
2745 This wrapper is considered experimental. Some of the wrapped filters
2746 may not work properly and we may drop support for them, as they will
2747 be implemented natively into FFmpeg. Thus you should avoid
2748 depending on them when writing portable scripts.
2750 The filters accepts the parameters:
2751 @var{filter_name}[:=]@var{filter_params}
2753 @var{filter_name} is the name of a supported MPlayer filter,
2754 @var{filter_params} is a string containing the parameters accepted by
2757 The list of the currently supported filters follows:
2792 The parameter syntax and behavior for the listed filters are the same
2793 of the corresponding MPlayer filters. For detailed instructions check
2794 the "VIDEO FILTERS" section in the MPlayer manual.
2796 Some examples follow:
2799 Adjust gamma, brightness, contrast:
2805 Add temporal noise to input video:
2811 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
2817 This filter accepts an integer in input, if non-zero it negates the
2818 alpha component (if available). The default value in input is 0.
2822 Force libavfilter not to use any of the specified pixel formats for the
2823 input to the next filter.
2825 The filter accepts a list of pixel format names, separated by ":",
2826 for example "yuv420p:monow:rgb24".
2828 Some examples follow:
2830 # force libavfilter to use a format different from "yuv420p" for the
2831 # input to the vflip filter
2832 noformat=yuv420p,vflip
2834 # convert the input video to any of the formats not contained in the list
2835 noformat=yuv420p:yuv444p:yuv410p
2840 Pass the video source unchanged to the output.
2844 Apply video transform using libopencv.
2846 To enable this filter install libopencv library and headers and
2847 configure FFmpeg with @code{--enable-libopencv}.
2849 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
2851 @var{filter_name} is the name of the libopencv filter to apply.
2853 @var{filter_params} specifies the parameters to pass to the libopencv
2854 filter. If not specified the default values are assumed.
2856 Refer to the official libopencv documentation for more precise
2858 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
2860 Follows the list of supported libopencv filters.
2865 Dilate an image by using a specific structuring element.
2866 This filter corresponds to the libopencv function @code{cvDilate}.
2868 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
2870 @var{struct_el} represents a structuring element, and has the syntax:
2871 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
2873 @var{cols} and @var{rows} represent the number of columns and rows of
2874 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
2875 point, and @var{shape} the shape for the structuring element, and
2876 can be one of the values "rect", "cross", "ellipse", "custom".
2878 If the value for @var{shape} is "custom", it must be followed by a
2879 string of the form "=@var{filename}". The file with name
2880 @var{filename} is assumed to represent a binary image, with each
2881 printable character corresponding to a bright pixel. When a custom
2882 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
2883 or columns and rows of the read file are assumed instead.
2885 The default value for @var{struct_el} is "3x3+0x0/rect".
2887 @var{nb_iterations} specifies the number of times the transform is
2888 applied to the image, and defaults to 1.
2890 Follow some example:
2892 # use the default values
2895 # dilate using a structuring element with a 5x5 cross, iterate two times
2896 ocv=dilate=5x5+2x2/cross:2
2898 # read the shape from the file diamond.shape, iterate two times
2899 # the file diamond.shape may contain a pattern of characters like this:
2905 # the specified cols and rows are ignored (but not the anchor point coordinates)
2906 ocv=0x0+2x2/custom=diamond.shape:2
2911 Erode an image by using a specific structuring element.
2912 This filter corresponds to the libopencv function @code{cvErode}.
2914 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
2915 with the same syntax and semantics as the @ref{dilate} filter.
2919 Smooth the input video.
2921 The filter takes the following parameters:
2922 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
2924 @var{type} is the type of smooth filter to apply, and can be one of
2925 the following values: "blur", "blur_no_scale", "median", "gaussian",
2926 "bilateral". The default value is "gaussian".
2928 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
2929 parameters whose meanings depend on smooth type. @var{param1} and
2930 @var{param2} accept integer positive values or 0, @var{param3} and
2931 @var{param4} accept float values.
2933 The default value for @var{param1} is 3, the default value for the
2934 other parameters is 0.
2936 These parameters correspond to the parameters assigned to the
2937 libopencv function @code{cvSmooth}.
2942 Overlay one video on top of another.
2944 It takes two inputs and one output, the first input is the "main"
2945 video on which the second input is overlayed.
2947 It accepts the parameters: @var{x}:@var{y}[:@var{options}].
2949 @var{x} is the x coordinate of the overlayed video on the main video,
2950 @var{y} is the y coordinate. @var{x} and @var{y} are expressions containing
2951 the following parameters:
2954 @item main_w, main_h
2955 main input width and height
2958 same as @var{main_w} and @var{main_h}
2960 @item overlay_w, overlay_h
2961 overlay input width and height
2964 same as @var{overlay_w} and @var{overlay_h}
2967 @var{options} is an optional list of @var{key}=@var{value} pairs,
2970 The description of the accepted options follows.
2974 If set to 1, force the filter to accept inputs in the RGB
2975 color space. Default value is 0.
2978 Be aware that frames are taken from each input video in timestamp
2979 order, hence, if their initial timestamps differ, it is a a good idea
2980 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
2981 have them begin in the same zero timestamp, as it does the example for
2982 the @var{movie} filter.
2984 Follow some examples:
2986 # draw the overlay at 10 pixels from the bottom right
2987 # corner of the main video.
2988 overlay=main_w-overlay_w-10:main_h-overlay_h-10
2990 # insert a transparent PNG logo in the bottom left corner of the input
2991 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
2993 # insert 2 different transparent PNG logos (second logo on bottom
2995 ffmpeg -i input -i logo1 -i logo2 -filter_complex
2996 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
2998 # add a transparent color layer on top of the main video,
2999 # WxH specifies the size of the main input to the overlay filter
3000 color=red@@.3:WxH [over]; [in][over] overlay [out]
3002 # play an original video and a filtered version (here with the deshake filter)
3004 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
3006 # the previous example is the same as:
3007 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
3010 You can chain together more overlays but the efficiency of such
3011 approach is yet to be tested.
3015 Add paddings to the input image, and places the original input at the
3016 given coordinates @var{x}, @var{y}.
3018 It accepts the following parameters:
3019 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
3021 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
3022 expressions containing the following constants:
3026 the input video width and height
3029 same as @var{in_w} and @var{in_h}
3032 the output width and height, that is the size of the padded area as
3033 specified by the @var{width} and @var{height} expressions
3036 same as @var{out_w} and @var{out_h}
3039 x and y offsets as specified by the @var{x} and @var{y}
3040 expressions, or NAN if not yet specified
3043 same as @var{iw} / @var{ih}
3046 input sample aspect ratio
3049 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3052 horizontal and vertical chroma subsample values. For example for the
3053 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3056 Follows the description of the accepted parameters.
3061 Specify the size of the output image with the paddings added. If the
3062 value for @var{width} or @var{height} is 0, the corresponding input size
3063 is used for the output.
3065 The @var{width} expression can reference the value set by the
3066 @var{height} expression, and vice versa.
3068 The default value of @var{width} and @var{height} is 0.
3072 Specify the offsets where to place the input image in the padded area
3073 with respect to the top/left border of the output image.
3075 The @var{x} expression can reference the value set by the @var{y}
3076 expression, and vice versa.
3078 The default value of @var{x} and @var{y} is 0.
3082 Specify the color of the padded area, it can be the name of a color
3083 (case insensitive match) or a 0xRRGGBB[AA] sequence.
3085 The default value of @var{color} is "black".
3089 @subsection Examples
3093 Add paddings with color "violet" to the input video. Output video
3094 size is 640x480, the top-left corner of the input video is placed at
3097 pad=640:480:0:40:violet
3101 Pad the input to get an output with dimensions increased by 3/2,
3102 and put the input video at the center of the padded area:
3104 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
3108 Pad the input to get a squared output with size equal to the maximum
3109 value between the input width and height, and put the input video at
3110 the center of the padded area:
3112 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
3116 Pad the input to get a final w/h ratio of 16:9:
3118 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
3122 In case of anamorphic video, in order to set the output display aspect
3123 correctly, it is necessary to use @var{sar} in the expression,
3124 according to the relation:
3126 (ih * X / ih) * sar = output_dar
3127 X = output_dar / sar
3130 Thus the previous example needs to be modified to:
3132 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
3136 Double output size and put the input video in the bottom-right
3137 corner of the output padded area:
3139 pad="2*iw:2*ih:ow-iw:oh-ih"
3143 @section pixdesctest
3145 Pixel format descriptor test filter, mainly useful for internal
3146 testing. The output video should be equal to the input video.
3150 format=monow, pixdesctest
3153 can be used to test the monowhite pixel format descriptor definition.
3157 Suppress a TV station logo, using an image file to determine which
3158 pixels comprise the logo. It works by filling in the pixels that
3159 comprise the logo with neighboring pixels.
3161 This filter requires one argument which specifies the filter bitmap
3162 file, which can be any image format supported by libavformat. The
3163 width and height of the image file must match those of the video
3164 stream being processed.
3166 Pixels in the provided bitmap image with a value of zero are not
3167 considered part of the logo, non-zero pixels are considered part of
3168 the logo. If you use white (255) for the logo and black (0) for the
3169 rest, you will be safe. For making the filter bitmap, it is
3170 recommended to take a screen capture of a black frame with the logo
3171 visible, and then using a threshold filter followed by the erode
3172 filter once or twice.
3174 If needed, little splotches can be fixed manually. Remember that if
3175 logo pixels are not covered, the filter quality will be much
3176 reduced. Marking too many pixels as part of the logo does not hurt as
3177 much, but it will increase the amount of blurring needed to cover over
3178 the image and will destroy more information than necessary, and extra
3179 pixels will slow things down on a large logo.
3183 Scale (resize) the input video, using the libswscale library.
3185 The scale filter forces the output display aspect ratio to be the same
3186 of the input, by changing the output sample aspect ratio.
3188 This filter accepts a list of named options in the form of
3189 @var{key}=@var{value} pairs separated by ":". If the key for the first
3190 two options is not specified, the assumed keys for the first two
3191 values are @code{w} and @code{h}. If the first option has no key and
3192 can be interpreted like a video size specification, it will be used
3193 to set the video size.
3195 A description of the accepted options follows.
3199 Set the video width expression, default value is @code{iw}. See below
3200 for the list of accepted constants.
3203 Set the video heiht expression, default value is @code{ih}.
3204 See below for the list of accepted constants.
3207 Set the interlacing. It accepts the following values:
3211 force interlaced aware scaling
3214 do not apply interlaced scaling
3217 select interlaced aware scaling depending on whether the source frames
3218 are flagged as interlaced or not
3221 Default value is @code{0}.
3224 Set libswscale scaling flags. If not explictly specified the filter
3225 applies a bilinear scaling algorithm.
3228 Set the video size, the value must be a valid abbreviation or in the
3229 form @var{width}x@var{height}.
3232 The values of the @var{w} and @var{h} options are expressions
3233 containing the following constants:
3237 the input width and height
3240 same as @var{in_w} and @var{in_h}
3243 the output (cropped) width and height
3246 same as @var{out_w} and @var{out_h}
3249 same as @var{iw} / @var{ih}
3252 input sample aspect ratio
3255 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3258 horizontal and vertical chroma subsample values. For example for the
3259 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3262 If the input image format is different from the format requested by
3263 the next filter, the scale filter will convert the input to the
3266 If the value for @var{width} or @var{height} is 0, the respective input
3267 size is used for the output.
3269 If the value for @var{width} or @var{height} is -1, the scale filter will
3270 use, for the respective output size, a value that maintains the aspect
3271 ratio of the input image.
3273 @subsection Examples
3277 Scale the input video to a size of 200x100:
3282 This is equivalent to:
3293 Specify a size abbreviation for the output size:
3298 which can also be written as:
3304 Scale the input to 2x:
3310 The above is the same as:
3316 Scale the input to 2x with forced interlaced scaling:
3318 scale=2*iw:2*ih:interl=1
3322 Scale the input to half size:
3328 Increase the width, and set the height to the same size:
3334 Seek for Greek harmony:
3341 Increase the height, and set the width to 3/2 of the height:
3347 Increase the size, but make the size a multiple of the chroma:
3349 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
3353 Increase the width to a maximum of 500 pixels, keep the same input
3356 scale='min(500\, iw*3/2):-1'
3361 Select frames to pass in output.
3363 It accepts in input an expression, which is evaluated for each input
3364 frame. If the expression is evaluated to a non-zero value, the frame
3365 is selected and passed to the output, otherwise it is discarded.
3367 The expression can contain the following constants:
3371 the sequential number of the filtered frame, starting from 0
3374 the sequential number of the selected frame, starting from 0
3376 @item prev_selected_n
3377 the sequential number of the last selected frame, NAN if undefined
3380 timebase of the input timestamps
3383 the PTS (Presentation TimeStamp) of the filtered video frame,
3384 expressed in @var{TB} units, NAN if undefined
3387 the PTS (Presentation TimeStamp) of the filtered video frame,
3388 expressed in seconds, NAN if undefined
3391 the PTS of the previously filtered video frame, NAN if undefined
3393 @item prev_selected_pts
3394 the PTS of the last previously filtered video frame, NAN if undefined
3396 @item prev_selected_t
3397 the PTS of the last previously selected video frame, NAN if undefined
3400 the PTS of the first video frame in the video, NAN if undefined
3403 the time of the first video frame in the video, NAN if undefined
3406 the type of the filtered frame, can assume one of the following
3418 @item interlace_type
3419 the frame interlace type, can assume one of the following values:
3422 the frame is progressive (not interlaced)
3424 the frame is top-field-first
3426 the frame is bottom-field-first
3430 1 if the filtered frame is a key-frame, 0 otherwise
3433 the position in the file of the filtered frame, -1 if the information
3434 is not available (e.g. for synthetic video)
3437 value between 0 and 1 to indicate a new scene; a low value reflects a low
3438 probability for the current frame to introduce a new scene, while a higher
3439 value means the current frame is more likely to be one (see the example below)
3443 The default value of the select expression is "1".
3445 Some examples follow:
3448 # select all frames in input
3451 # the above is the same as:
3457 # select only I-frames
3458 select='eq(pict_type\,I)'
3460 # select one frame every 100
3461 select='not(mod(n\,100))'
3463 # select only frames contained in the 10-20 time interval
3464 select='gte(t\,10)*lte(t\,20)'
3466 # select only I frames contained in the 10-20 time interval
3467 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
3469 # select frames with a minimum distance of 10 seconds
3470 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
3473 Complete example to create a mosaic of the first scenes:
3476 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
3479 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
3482 @section setdar, setsar
3484 The @code{setdar} filter sets the Display Aspect Ratio for the filter
3487 This is done by changing the specified Sample (aka Pixel) Aspect
3488 Ratio, according to the following equation:
3490 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
3493 Keep in mind that the @code{setdar} filter does not modify the pixel
3494 dimensions of the video frame. Also the display aspect ratio set by
3495 this filter may be changed by later filters in the filterchain,
3496 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
3499 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
3500 the filter output video.
3502 Note that as a consequence of the application of this filter, the
3503 output display aspect ratio will change according to the equation
3506 Keep in mind that the sample aspect ratio set by the @code{setsar}
3507 filter may be changed by later filters in the filterchain, e.g. if
3508 another "setsar" or a "setdar" filter is applied.
3510 The @code{setdar} and @code{setsar} filters accept a string in the
3511 form @var{num}:@var{den} expressing an aspect ratio, or the following
3512 named options, expressed as a sequence of @var{key}=@var{value} pairs,
3517 Set the maximum integer value to use for expressing numerator and
3518 denominator when reducing the expressed aspect ratio to a rational.
3519 Default value is @code{100}.
3522 Set the aspect ratio used by the filter.
3524 The parameter can be a floating point number string, an expression, or
3525 a string of the form @var{num}:@var{den}, where @var{num} and
3526 @var{den} are the numerator and denominator of the aspect ratio. If
3527 the parameter is not specified, it is assumed the value "0".
3528 In case the form "@var{num}:@var{den}" the @code{:} character should
3532 If the keys are omitted in the named options list, the specifed values
3533 are assumed to be @var{ratio} and @var{max} in that order.
3535 For example to change the display aspect ratio to 16:9, specify:
3540 The example above is equivalent to:
3545 To change the sample aspect ratio to 10:11, specify:
3550 To set a display aspect ratio of 16:9, and specify a maximum integer value of
3551 1000 in the aspect ratio reduction, use the command:
3553 setdar=ratio='16:9':max=1000
3558 Force field for the output video frame.
3560 The @code{setfield} filter marks the interlace type field for the
3561 output frames. It does not change the input frame, but only sets the
3562 corresponding property, which affects how the frame is treated by
3563 following filters (e.g. @code{fieldorder} or @code{yadif}).
3565 It accepts a string parameter, which can assume the following values:
3568 Keep the same field property.
3571 Mark the frame as bottom-field-first.
3574 Mark the frame as top-field-first.
3577 Mark the frame as progressive.
3582 Show a line containing various information for each input video frame.
3583 The input video is not modified.
3585 The shown line contains a sequence of key/value pairs of the form
3586 @var{key}:@var{value}.
3588 A description of each shown parameter follows:
3592 sequential number of the input frame, starting from 0
3595 Presentation TimeStamp of the input frame, expressed as a number of
3596 time base units. The time base unit depends on the filter input pad.
3599 Presentation TimeStamp of the input frame, expressed as a number of
3603 position of the frame in the input stream, -1 if this information in
3604 unavailable and/or meaningless (for example in case of synthetic video)
3610 sample aspect ratio of the input frame, expressed in the form
3614 size of the input frame, expressed in the form
3615 @var{width}x@var{height}
3618 interlaced mode ("P" for "progressive", "T" for top field first, "B"
3619 for bottom field first)
3622 1 if the frame is a key frame, 0 otherwise
3625 picture type of the input frame ("I" for an I-frame, "P" for a
3626 P-frame, "B" for a B-frame, "?" for unknown type).
3627 Check also the documentation of the @code{AVPictureType} enum and of
3628 the @code{av_get_picture_type_char} function defined in
3629 @file{libavutil/avutil.h}.
3632 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
3634 @item plane_checksum
3635 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
3636 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
3641 Pass the images of input video on to next video filter as multiple
3645 ffmpeg -i in.avi -vf "slicify=32" out.avi
3648 The filter accepts the slice height as parameter. If the parameter is
3649 not specified it will use the default value of 16.
3651 Adding this in the beginning of filter chains should make filtering
3652 faster due to better use of the memory cache.
3656 Blur the input video without impacting the outlines.
3658 The filter accepts the following parameters:
3659 @var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
3661 Parameters prefixed by @var{luma} indicate that they work on the
3662 luminance of the pixels whereas parameters prefixed by @var{chroma}
3663 refer to the chrominance of the pixels.
3665 If the chroma parameters are not set, the luma parameters are used for
3666 either the luminance and the chrominance of the pixels.
3668 @var{luma_radius} or @var{chroma_radius} must be a float number in the
3669 range [0.1,5.0] that specifies the variance of the gaussian filter
3670 used to blur the image (slower if larger).
3672 @var{luma_strength} or @var{chroma_strength} must be a float number in
3673 the range [-1.0,1.0] that configures the blurring. A value included in
3674 [0.0,1.0] will blur the image whereas a value included in [-1.0,0.0]
3675 will sharpen the image.
3677 @var{luma_threshold} or @var{chroma_threshold} must be an integer in
3678 the range [-30,30] that is used as a coefficient to determine whether
3679 a pixel should be blurred or not. A value of 0 will filter all the
3680 image, a value included in [0,30] will filter flat areas and a value
3681 included in [-30,0] will filter edges.
3685 Split input video into several identical outputs.
3687 The filter accepts a single parameter which specifies the number of outputs. If
3688 unspecified, it defaults to 2.
3692 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
3694 will create 5 copies of the input video.
3698 [in] split [splitout1][splitout2];
3699 [splitout1] crop=100:100:0:0 [cropout];
3700 [splitout2] pad=200:200:100:100 [padout];
3703 will create two separate outputs from the same input, one cropped and
3708 Scale the input by 2x and smooth using the Super2xSaI (Scale and
3709 Interpolate) pixel art scaling algorithm.
3711 Useful for enlarging pixel art images without reducing sharpness.
3717 Select the most representative frame in a given sequence of consecutive frames.
3719 It accepts as argument the frames batch size to analyze (default @var{N}=100);
3720 in a set of @var{N} frames, the filter will pick one of them, and then handle
3721 the next batch of @var{N} frames until the end.
3723 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
3724 value will result in a higher memory usage, so a high value is not recommended.
3726 The following example extract one picture each 50 frames:
3731 Complete example of a thumbnail creation with @command{ffmpeg}:
3733 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
3738 Tile several successive frames together.
3740 It accepts a list of options in the form of @var{key}=@var{value} pairs
3741 separated by ":". A description of the accepted options follows.
3746 Set the grid size (i.e. the number of lines and columns) in the form
3750 Set the outer border margin in pixels.
3753 Set the inner border thickness (i.e. the number of pixels between frames). For
3754 more advanced padding options (such as having different values for the edges),
3755 refer to the pad video filter.
3758 Set the maximum number of frames to render in the given area. It must be less
3759 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
3760 the area will be used.
3764 Alternatively, the options can be specified as a flat string:
3766 @var{layout}[:@var{nb_frames}[:@var{margin}[:@var{padding}]]]
3768 For example, produce 8×8 PNG tiles of all keyframes (@option{-skip_frame
3771 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
3773 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
3774 duplicating each output frame to accomodate the originally detected frame
3777 Another example to display @code{5} pictures in an area of @code{3x2} frames,
3778 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
3779 mixed flat and named options:
3781 tile=3x2:nb_frames=5:padding=7:margin=2
3786 Perform various types of temporal field interlacing.
3788 Frames are counted starting from 1, so the first input frame is
3791 This filter accepts a single parameter specifying the mode. Available
3796 Move odd frames into the upper field, even into the lower field,
3797 generating a double height frame at half framerate.
3800 Only output even frames, odd frames are dropped, generating a frame with
3801 unchanged height at half framerate.
3804 Only output odd frames, even frames are dropped, generating a frame with
3805 unchanged height at half framerate.
3808 Expand each frame to full height, but pad alternate lines with black,
3809 generating a frame with double height at the same input framerate.
3811 @item interleave_top, 4
3812 Interleave the upper field from odd frames with the lower field from
3813 even frames, generating a frame with unchanged height at half framerate.
3815 @item interleave_bottom, 5
3816 Interleave the lower field from odd frames with the upper field from
3817 even frames, generating a frame with unchanged height at half framerate.
3819 @item interlacex2, 6
3820 Double frame rate with unchanged height. Frames are inserted each
3821 containing the second temporal field from the previous input frame and
3822 the first temporal field from the next input frame. This mode relies on
3823 the top_field_first flag. Useful for interlaced video displays with no
3824 field synchronisation.
3827 Numeric values are deprecated but are accepted for backward
3828 compatibility reasons.
3830 Default mode is @code{merge}.
3834 Transpose rows with columns in the input video and optionally flip it.
3836 This filter accepts the following named parameters:
3840 Specify the transposition direction. Can assume the following values:
3844 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
3852 Rotate by 90 degrees clockwise, that is:
3860 Rotate by 90 degrees counterclockwise, that is:
3868 Rotate by 90 degrees clockwise and vertically flip, that is:
3876 For values between 4-7, the transposition is only done if the input
3877 video geometry is portrait and not landscape. These values are
3878 deprecated, the @code{passthrough} option should be used instead.
3881 Do not apply the transposition if the input geometry matches the one
3882 specified by the specified value. It accepts the following values:
3885 Always apply transposition.
3887 Preserve portrait geometry (when @var{height} >= @var{width}).
3889 Preserve landscape geometry (when @var{width} >= @var{height}).
3892 Default value is @code{none}.
3897 Sharpen or blur the input video.
3899 It accepts the following parameters:
3900 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
3902 Negative values for the amount will blur the input video, while positive
3903 values will sharpen. All parameters are optional and default to the
3904 equivalent of the string '5:5:1.0:5:5:0.0'.
3909 Set the luma matrix horizontal size. It can be an integer between 3
3910 and 13, default value is 5.
3913 Set the luma matrix vertical size. It can be an integer between 3
3914 and 13, default value is 5.
3917 Set the luma effect strength. It can be a float number between -2.0
3918 and 5.0, default value is 1.0.
3920 @item chroma_msize_x
3921 Set the chroma matrix horizontal size. It can be an integer between 3
3922 and 13, default value is 5.
3924 @item chroma_msize_y
3925 Set the chroma matrix vertical size. It can be an integer between 3
3926 and 13, default value is 5.
3929 Set the chroma effect strength. It can be a float number between -2.0
3930 and 5.0, default value is 0.0.
3935 # Strong luma sharpen effect parameters
3938 # Strong blur of both luma and chroma parameters
3939 unsharp=7:7:-2:7:7:-2
3941 # Use the default values with @command{ffmpeg}
3942 ffmpeg -i in.avi -vf "unsharp" out.mp4
3947 Flip the input video vertically.
3950 ffmpeg -i in.avi -vf "vflip" out.avi
3955 Deinterlace the input video ("yadif" means "yet another deinterlacing
3958 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
3960 @var{mode} specifies the interlacing mode to adopt, accepts one of the
3965 output 1 frame for each frame
3967 output 1 frame for each field
3969 like 0 but skips spatial interlacing check
3971 like 1 but skips spatial interlacing check
3976 @var{parity} specifies the picture field parity assumed for the input
3977 interlaced video, accepts one of the following values:
3981 assume top field first
3983 assume bottom field first
3985 enable automatic detection
3988 Default value is -1.
3989 If interlacing is unknown or decoder does not export this information,
3990 top field first will be assumed.
3992 @var{auto} specifies if deinterlacer should trust the interlaced flag
3993 and only deinterlace frames marked as interlaced
3997 deinterlace all frames
3999 only deinterlace frames marked as interlaced
4004 @c man end VIDEO FILTERS
4006 @chapter Video Sources
4007 @c man begin VIDEO SOURCES
4009 Below is a description of the currently available video sources.
4013 Buffer video frames, and make them available to the filter chain.
4015 This source is mainly intended for a programmatic use, in particular
4016 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
4018 It accepts a list of options in the form of @var{key}=@var{value} pairs
4019 separated by ":". A description of the accepted options follows.
4024 Specify the size (width and height) of the buffered video frames.
4027 A string representing the pixel format of the buffered video frames.
4028 It may be a number corresponding to a pixel format, or a pixel format
4032 Specify the timebase assumed by the timestamps of the buffered frames.
4035 Specify the frame rate expected for the video stream.
4038 Specify the sample aspect ratio assumed by the video frames.
4041 Specify the optional parameters to be used for the scale filter which
4042 is automatically inserted when an input change is detected in the
4043 input size or format.
4048 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
4051 will instruct the source to accept video frames with size 320x240 and
4052 with format "yuv410p", assuming 1/24 as the timestamps timebase and
4053 square pixels (1:1 sample aspect ratio).
4054 Since the pixel format with name "yuv410p" corresponds to the number 6
4055 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
4056 this example corresponds to:
4058 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
4061 Alternatively, the options can be specified as a flat string, but this
4062 syntax is deprecated:
4064 @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}]
4068 Create a pattern generated by an elementary cellular automaton.
4070 The initial state of the cellular automaton can be defined through the
4071 @option{filename}, and @option{pattern} options. If such options are
4072 not specified an initial state is created randomly.
4074 At each new frame a new row in the video is filled with the result of
4075 the cellular automaton next generation. The behavior when the whole
4076 frame is filled is defined by the @option{scroll} option.
4078 This source accepts a list of options in the form of
4079 @var{key}=@var{value} pairs separated by ":". A description of the
4080 accepted options follows.
4084 Read the initial cellular automaton state, i.e. the starting row, from
4086 In the file, each non-whitespace character is considered an alive
4087 cell, a newline will terminate the row, and further characters in the
4088 file will be ignored.
4091 Read the initial cellular automaton state, i.e. the starting row, from
4092 the specified string.
4094 Each non-whitespace character in the string is considered an alive
4095 cell, a newline will terminate the row, and further characters in the
4096 string will be ignored.
4099 Set the video rate, that is the number of frames generated per second.
4102 @item random_fill_ratio, ratio
4103 Set the random fill ratio for the initial cellular automaton row. It
4104 is a floating point number value ranging from 0 to 1, defaults to
4107 This option is ignored when a file or a pattern is specified.
4109 @item random_seed, seed
4110 Set the seed for filling randomly the initial row, must be an integer
4111 included between 0 and UINT32_MAX. If not specified, or if explicitly
4112 set to -1, the filter will try to use a good random seed on a best
4116 Set the cellular automaton rule, it is a number ranging from 0 to 255.
4117 Default value is 110.
4120 Set the size of the output video.
4122 If @option{filename} or @option{pattern} is specified, the size is set
4123 by default to the width of the specified initial state row, and the
4124 height is set to @var{width} * PHI.
4126 If @option{size} is set, it must contain the width of the specified
4127 pattern string, and the specified pattern will be centered in the
4130 If a filename or a pattern string is not specified, the size value
4131 defaults to "320x518" (used for a randomly generated initial state).
4134 If set to 1, scroll the output upward when all the rows in the output
4135 have been already filled. If set to 0, the new generated row will be
4136 written over the top row just after the bottom row is filled.
4139 @item start_full, full
4140 If set to 1, completely fill the output with generated rows before
4141 outputting the first frame.
4142 This is the default behavior, for disabling set the value to 0.
4145 If set to 1, stitch the left and right row edges together.
4146 This is the default behavior, for disabling set the value to 0.
4149 @subsection Examples
4153 Read the initial state from @file{pattern}, and specify an output of
4156 cellauto=f=pattern:s=200x400
4160 Generate a random initial row with a width of 200 cells, with a fill
4163 cellauto=ratio=2/3:s=200x200
4167 Create a pattern generated by rule 18 starting by a single alive cell
4168 centered on an initial row with width 100:
4170 cellauto=p=@@:s=100x400:full=0:rule=18
4174 Specify a more elaborated initial pattern:
4176 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
4183 Generate a Mandelbrot set fractal, and progressively zoom towards the
4184 point specified with @var{start_x} and @var{start_y}.
4186 This source accepts a list of options in the form of
4187 @var{key}=@var{value} pairs separated by ":". A description of the
4188 accepted options follows.
4193 Set the terminal pts value. Default value is 400.
4196 Set the terminal scale value.
4197 Must be a floating point value. Default value is 0.3.
4200 Set the inner coloring mode, that is the algorithm used to draw the
4201 Mandelbrot fractal internal region.
4203 It shall assume one of the following values:
4208 Show time until convergence.
4210 Set color based on point closest to the origin of the iterations.
4215 Default value is @var{mincol}.
4218 Set the bailout value. Default value is 10.0.
4221 Set the maximum of iterations performed by the rendering
4222 algorithm. Default value is 7189.
4225 Set outer coloring mode.
4226 It shall assume one of following values:
4228 @item iteration_count
4229 Set iteration cound mode.
4230 @item normalized_iteration_count
4231 set normalized iteration count mode.
4233 Default value is @var{normalized_iteration_count}.
4236 Set frame rate, expressed as number of frames per second. Default
4240 Set frame size. Default value is "640x480".
4243 Set the initial scale value. Default value is 3.0.
4246 Set the initial x position. Must be a floating point value between
4247 -100 and 100. Default value is -0.743643887037158704752191506114774.
4250 Set the initial y position. Must be a floating point value between
4251 -100 and 100. Default value is -0.131825904205311970493132056385139.
4256 Generate various test patterns, as generated by the MPlayer test filter.
4258 The size of the generated video is fixed, and is 256x256.
4259 This source is useful in particular for testing encoding features.
4261 This source accepts an optional sequence of @var{key}=@var{value} pairs,
4262 separated by ":". The description of the accepted options follows.
4267 Specify the frame rate of the sourced video, as the number of frames
4268 generated per second. It has to be a string in the format
4269 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
4270 number or a valid video frame rate abbreviation. The default value is
4274 Set the video duration of the sourced video. The accepted syntax is:
4279 See also the function @code{av_parse_time()}.
4281 If not specified, or the expressed duration is negative, the video is
4282 supposed to be generated forever.
4286 Set the number or the name of the test to perform. Supported tests are:
4301 Default value is "all", which will cycle through the list of all tests.
4304 For example the following:
4309 will generate a "dc_luma" test pattern.
4313 Provide a frei0r source.
4315 To enable compilation of this filter you need to install the frei0r
4316 header and configure FFmpeg with @code{--enable-frei0r}.
4318 The source supports the syntax:
4320 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
4323 @var{size} is the size of the video to generate, may be a string of the
4324 form @var{width}x@var{height} or a frame size abbreviation.
4325 @var{rate} is the rate of the video to generate, may be a string of
4326 the form @var{num}/@var{den} or a frame rate abbreviation.
4327 @var{src_name} is the name to the frei0r source to load. For more
4328 information regarding frei0r and how to set the parameters read the
4329 section @ref{frei0r} in the description of the video filters.
4331 For example, to generate a frei0r partik0l source with size 200x200
4332 and frame rate 10 which is overlayed on the overlay filter main input:
4334 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
4339 Generate a life pattern.
4341 This source is based on a generalization of John Conway's life game.
4343 The sourced input represents a life grid, each pixel represents a cell
4344 which can be in one of two possible states, alive or dead. Every cell
4345 interacts with its eight neighbours, which are the cells that are
4346 horizontally, vertically, or diagonally adjacent.
4348 At each interaction the grid evolves according to the adopted rule,
4349 which specifies the number of neighbor alive cells which will make a
4350 cell stay alive or born. The @option{rule} option allows to specify
4353 This source accepts a list of options in the form of
4354 @var{key}=@var{value} pairs separated by ":". A description of the
4355 accepted options follows.
4359 Set the file from which to read the initial grid state. In the file,
4360 each non-whitespace character is considered an alive cell, and newline
4361 is used to delimit the end of each row.
4363 If this option is not specified, the initial grid is generated
4367 Set the video rate, that is the number of frames generated per second.
4370 @item random_fill_ratio, ratio
4371 Set the random fill ratio for the initial random grid. It is a
4372 floating point number value ranging from 0 to 1, defaults to 1/PHI.
4373 It is ignored when a file is specified.
4375 @item random_seed, seed
4376 Set the seed for filling the initial random grid, must be an integer
4377 included between 0 and UINT32_MAX. If not specified, or if explicitly
4378 set to -1, the filter will try to use a good random seed on a best
4384 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
4385 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
4386 @var{NS} specifies the number of alive neighbor cells which make a
4387 live cell stay alive, and @var{NB} the number of alive neighbor cells
4388 which make a dead cell to become alive (i.e. to "born").
4389 "s" and "b" can be used in place of "S" and "B", respectively.
4391 Alternatively a rule can be specified by an 18-bits integer. The 9
4392 high order bits are used to encode the next cell state if it is alive
4393 for each number of neighbor alive cells, the low order bits specify
4394 the rule for "borning" new cells. Higher order bits encode for an
4395 higher number of neighbor cells.
4396 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
4397 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
4399 Default value is "S23/B3", which is the original Conway's game of life
4400 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
4401 cells, and will born a new cell if there are three alive cells around
4405 Set the size of the output video.
4407 If @option{filename} is specified, the size is set by default to the
4408 same size of the input file. If @option{size} is set, it must contain
4409 the size specified in the input file, and the initial grid defined in
4410 that file is centered in the larger resulting area.
4412 If a filename is not specified, the size value defaults to "320x240"
4413 (used for a randomly generated initial grid).
4416 If set to 1, stitch the left and right grid edges together, and the
4417 top and bottom edges also. Defaults to 1.
4420 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
4421 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
4422 value from 0 to 255.
4425 Set the color of living (or new born) cells.
4428 Set the color of dead cells. If @option{mold} is set, this is the first color
4429 used to represent a dead cell.
4432 Set mold color, for definitely dead and moldy cells.
4435 @subsection Examples
4439 Read a grid from @file{pattern}, and center it on a grid of size
4442 life=f=pattern:s=300x300
4446 Generate a random grid of size 200x200, with a fill ratio of 2/3:
4448 life=ratio=2/3:s=200x200
4452 Specify a custom rule for evolving a randomly generated grid:
4458 Full example with slow death effect (mold) using @command{ffplay}:
4460 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
4464 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
4466 The @code{color} source provides an uniformly colored input.
4468 The @code{nullsrc} source returns unprocessed video frames. It is
4469 mainly useful to be employed in analysis / debugging tools, or as the
4470 source for filters which ignore the input data.
4472 The @code{rgbtestsrc} source generates an RGB test pattern useful for
4473 detecting RGB vs BGR issues. You should see a red, green and blue
4474 stripe from top to bottom.
4476 The @code{smptebars} source generates a color bars pattern, based on
4477 the SMPTE Engineering Guideline EG 1-1990.
4479 The @code{testsrc} source generates a test video pattern, showing a
4480 color pattern, a scrolling gradient and a timestamp. This is mainly
4481 intended for testing purposes.
4483 These sources accept an optional sequence of @var{key}=@var{value} pairs,
4484 separated by ":". The description of the accepted options follows.
4489 Specify the color of the source, only used in the @code{color}
4490 source. It can be the name of a color (case insensitive match) or a
4491 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
4492 default value is "black".
4495 Specify the size of the sourced video, it may be a string of the form
4496 @var{width}x@var{height}, or the name of a size abbreviation. The
4497 default value is "320x240".
4500 Specify the frame rate of the sourced video, as the number of frames
4501 generated per second. It has to be a string in the format
4502 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
4503 number or a valid video frame rate abbreviation. The default value is
4507 Set the sample aspect ratio of the sourced video.
4510 Set the video duration of the sourced video. The accepted syntax is:
4512 [-]HH[:MM[:SS[.m...]]]
4515 See also the function @code{av_parse_time()}.
4517 If not specified, or the expressed duration is negative, the video is
4518 supposed to be generated forever.
4521 Set the number of decimals to show in the timestamp, only used in the
4522 @code{testsrc} source.
4524 The displayed timestamp value will correspond to the original
4525 timestamp value multiplied by the power of 10 of the specified
4526 value. Default value is 0.
4529 For example the following:
4531 testsrc=duration=5.3:size=qcif:rate=10
4534 will generate a video with a duration of 5.3 seconds, with size
4535 176x144 and a frame rate of 10 frames per second.
4537 The following graph description will generate a red source
4538 with an opacity of 0.2, with size "qcif" and a frame rate of 10
4541 color=c=red@@0.2:s=qcif:r=10
4544 If the input content is to be ignored, @code{nullsrc} can be used. The
4545 following command generates noise in the luminance plane by employing
4546 the @code{geq} filter:
4548 nullsrc=s=256x256, geq=random(1)*255:128:128
4551 @c man end VIDEO SOURCES
4553 @chapter Video Sinks
4554 @c man begin VIDEO SINKS
4556 Below is a description of the currently available video sinks.
4560 Buffer video frames, and make them available to the end of the filter
4563 This sink is mainly intended for a programmatic use, in particular
4564 through the interface defined in @file{libavfilter/buffersink.h}.
4566 It does not require a string parameter in input, but you need to
4567 specify a pointer to a list of supported pixel formats terminated by
4568 -1 in the opaque parameter provided to @code{avfilter_init_filter}
4569 when initializing this sink.
4573 Null video sink, do absolutely nothing with the input video. It is
4574 mainly useful as a template and to be employed in analysis / debugging
4577 @c man end VIDEO SINKS
4579 @chapter Multimedia Filters
4580 @c man begin MULTIMEDIA FILTERS
4582 Below is a description of the currently available multimedia filters.
4584 @section asendcmd, sendcmd
4586 Send commands to filters in the filtergraph.
4588 These filters read commands to be sent to other filters in the
4591 @code{asendcmd} must be inserted between two audio filters,
4592 @code{sendcmd} must be inserted between two video filters, but apart
4593 from that they act the same way.
4595 The specification of commands can be provided in the filter arguments
4596 with the @var{commands} option, or in a file specified by the
4597 @var{filename} option.
4599 These filters accept the following options:
4602 Set the commands to be read and sent to the other filters.
4604 Set the filename of the commands to be read and sent to the other
4608 @subsection Commands syntax
4610 A commands description consists of a sequence of interval
4611 specifications, comprising a list of commands to be executed when a
4612 particular event related to that interval occurs. The occurring event
4613 is typically the current frame time entering or leaving a given time
4616 An interval is specified by the following syntax:
4618 @var{START}[-@var{END}] @var{COMMANDS};
4621 The time interval is specified by the @var{START} and @var{END} times.
4622 @var{END} is optional and defaults to the maximum time.
4624 The current frame time is considered within the specified interval if
4625 it is included in the interval [@var{START}, @var{END}), that is when
4626 the time is greater or equal to @var{START} and is lesser than
4629 @var{COMMANDS} consists of a sequence of one or more command
4630 specifications, separated by ",", relating to that interval. The
4631 syntax of a command specification is given by:
4633 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
4636 @var{FLAGS} is optional and specifies the type of events relating to
4637 the time interval which enable sending the specified command, and must
4638 be a non-null sequence of identifier flags separated by "+" or "|" and
4639 enclosed between "[" and "]".
4641 The following flags are recognized:
4644 The command is sent when the current frame timestamp enters the
4645 specified interval. In other words, the command is sent when the
4646 previous frame timestamp was not in the given interval, and the
4650 The command is sent when the current frame timestamp leaves the
4651 specified interval. In other words, the command is sent when the
4652 previous frame timestamp was in the given interval, and the
4656 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
4659 @var{TARGET} specifies the target of the command, usually the name of
4660 the filter class or a specific filter instance name.
4662 @var{COMMAND} specifies the name of the command for the target filter.
4664 @var{ARG} is optional and specifies the optional list of argument for
4665 the given @var{COMMAND}.
4667 Between one interval specification and another, whitespaces, or
4668 sequences of characters starting with @code{#} until the end of line,
4669 are ignored and can be used to annotate comments.
4671 A simplified BNF description of the commands specification syntax
4674 @var{COMMAND_FLAG} ::= "enter" | "leave"
4675 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
4676 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
4677 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
4678 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
4679 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
4682 @subsection Examples
4686 Specify audio tempo change at second 4:
4688 asendcmd=c='4.0 atempo tempo 1.5',atempo
4692 Specify a list of drawtext and hue commands in a file.
4694 # show text in the interval 5-10
4695 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
4696 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
4698 # desaturate the image in the interval 15-20
4699 15.0-20.0 [enter] hue reinit s=0,
4700 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
4701 [leave] hue reinit s=1,
4702 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
4704 # apply an exponential saturation fade-out effect, starting from time 25
4705 25 [enter] hue s=exp(t-25)
4708 A filtergraph allowing to read and process the above command list
4709 stored in a file @file{test.cmd}, can be specified with:
4711 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
4715 @section asetpts, setpts
4717 Change the PTS (presentation timestamp) of the input frames.
4719 @code{asetpts} works on audio frames, @code{setpts} on video frames.
4721 Accept in input an expression evaluated through the eval API, which
4722 can contain the following constants:
4726 frame rate, only defined for constant frame-rate video
4729 the presentation timestamp in input
4732 the count of the input frame, starting from 0.
4734 @item NB_CONSUMED_SAMPLES
4735 the number of consumed samples, not including the current frame (only
4739 the number of samples in the current frame (only audio)
4745 the PTS of the first frame
4748 the time in seconds of the first frame
4751 tell if the current frame is interlaced
4754 the time in seconds of the current frame
4760 original position in the file of the frame, or undefined if undefined
4761 for the current frame
4767 previous input time in seconds
4773 previous output time in seconds
4776 @subsection Examples
4780 Start counting PTS from zero
4786 Apply fast motion effect:
4792 Apply slow motion effect:
4798 Set fixed rate of 25 frames per second:
4804 Set fixed rate 25 fps with some jitter:
4806 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
4810 Apply an offset of 10 seconds to the input PTS:
4818 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
4819 it unchanged. By default, it logs a message at a frequency of 10Hz with the
4820 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
4821 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
4823 The filter also has a video output (see the @var{video} option) with a real
4824 time graph to observe the loudness evolution. The graphic contains the logged
4825 message mentioned above, so it is not printed anymore when this option is set,
4826 unless the verbose logging is set. The main graphing area contains the
4827 short-term loudness (3 seconds of analysis), and the gauge on the right is for
4828 the momentary loudness (400 milliseconds).
4830 More information about the Loudness Recommendation EBU R128 on
4831 @url{http://tech.ebu.ch/loudness}.
4833 The filter accepts the following named parameters:
4838 Activate the video output. The audio stream is passed unchanged whether this
4839 option is set or no. The video stream will be the first output stream if
4840 activated. Default is @code{0}.
4843 Set the video size. This option is for video only. Default and minimum
4844 resolution is @code{640x480}.
4847 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
4848 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
4849 other integer value between this range is allowed.
4853 Example of real-time graph using @command{ffplay}, with a EBU scale meter +18:
4855 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
4858 Run an analysis with @command{ffmpeg}:
4860 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
4863 @section settb, asettb
4865 Set the timebase to use for the output frames timestamps.
4866 It is mainly useful for testing timebase configuration.
4868 It accepts in input an arithmetic expression representing a rational.
4869 The expression can contain the constants "AVTB" (the
4870 default timebase), "intb" (the input timebase) and "sr" (the sample rate,
4873 The default value for the input is "intb".
4875 @subsection Examples
4879 Set the timebase to 1/25:
4885 Set the timebase to 1/10:
4891 Set the timebase to 1001/1000:
4897 Set the timebase to 2*intb:
4903 Set the default timebase value:
4911 Concatenate audio and video streams, joining them together one after the
4914 The filter works on segments of synchronized video and audio streams. All
4915 segments must have the same number of streams of each type, and that will
4916 also be the number of streams at output.
4918 The filter accepts the following named parameters:
4922 Set the number of segments. Default is 2.
4925 Set the number of output video streams, that is also the number of video
4926 streams in each segment. Default is 1.
4929 Set the number of output audio streams, that is also the number of video
4930 streams in each segment. Default is 0.
4933 Activate unsafe mode: do not fail if segments have a different format.
4937 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
4938 @var{a} audio outputs.
4940 There are @var{n}×(@var{v}+@var{a}) inputs: first the inputs for the first
4941 segment, in the same order as the outputs, then the inputs for the second
4944 Related streams do not always have exactly the same duration, for various
4945 reasons including codec frame size or sloppy authoring. For that reason,
4946 related synchronized streams (e.g. a video and its audio track) should be
4947 concatenated at once. The concat filter will use the duration of the longest
4948 stream in each segment (except the last one), and if necessary pad shorter
4949 audio streams with silence.
4951 For this filter to work correctly, all segments must start at timestamp 0.
4953 All corresponding streams must have the same parameters in all segments; the
4954 filtering system will automatically select a common pixel format for video
4955 streams, and a common sample format, sample rate and channel layout for
4956 audio streams, but other settings, such as resolution, must be converted
4957 explicitly by the user.
4959 Different frame rates are acceptable but will result in variable frame rate
4960 at output; be sure to configure the output file to handle it.
4965 Concatenate an opening, an episode and an ending, all in bilingual version
4966 (video in stream 0, audio in streams 1 and 2):
4968 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
4969 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
4970 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
4971 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
4975 Concatenate two parts, handling audio and video separately, using the
4976 (a)movie sources, and adjusting the resolution:
4978 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
4979 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
4980 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
4982 Note that a desync will happen at the stitch if the audio and video streams
4983 do not have exactly the same duration in the first file.
4987 @section showspectrum
4989 Convert input audio to a video output, representing the audio frequency
4992 The filter accepts the following named parameters:
4995 Specify the video size for the output. Default value is @code{640x480}.
4997 Specify if the spectrum should slide along the window. Default value is
5001 The usage is very similar to the showwaves filter; see the examples in that
5006 Convert input audio to a video output, representing the samples waves.
5008 The filter accepts the following named parameters:
5012 Set the number of samples which are printed on the same column. A
5013 larger value will decrease the frame rate. Must be a positive
5014 integer. This option can be set only if the value for @var{rate}
5015 is not explicitly specified.
5018 Set the (approximate) output frame rate. This is done by setting the
5019 option @var{n}. Default value is "25".
5022 Specify the video size for the output. Default value is "600x240".
5025 Some examples follow.
5028 Output the input file audio and the corresponding video representation
5031 amovie=a.mp3,asplit[out0],showwaves[out1]
5035 Create a synthetic signal and show it with showwaves, forcing a
5036 framerate of 30 frames per second:
5038 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
5042 @c man end MULTIMEDIA FILTERS
5044 @chapter Multimedia Sources
5045 @c man begin MULTIMEDIA SOURCES
5047 Below is a description of the currently available multimedia sources.
5051 This is the same as @ref{src_movie} source, except it selects an audio
5057 Read audio and/or video stream(s) from a movie container.
5059 It accepts the syntax: @var{movie_name}[:@var{options}] where
5060 @var{movie_name} is the name of the resource to read (not necessarily
5061 a file but also a device or a stream accessed through some protocol),
5062 and @var{options} is an optional sequence of @var{key}=@var{value}
5063 pairs, separated by ":".
5065 The description of the accepted options follows.
5069 @item format_name, f
5070 Specifies the format assumed for the movie to read, and can be either
5071 the name of a container or an input device. If not specified the
5072 format is guessed from @var{movie_name} or by probing.
5074 @item seek_point, sp
5075 Specifies the seek point in seconds, the frames will be output
5076 starting from this seek point, the parameter is evaluated with
5077 @code{av_strtod} so the numerical value may be suffixed by an IS
5078 postfix. Default value is "0".
5081 Specifies the streams to read. Several streams can be specified, separated
5082 by "+". The source will then have as many outputs, in the same order. The
5083 syntax is explained in the @ref{Stream specifiers} chapter. Two special
5084 names, "dv" and "da" specify respectively the default (best suited) video
5085 and audio stream. Default is "dv", or "da" if the filter is called as
5088 @item stream_index, si
5089 Specifies the index of the video stream to read. If the value is -1,
5090 the best suited video stream will be automatically selected. Default
5091 value is "-1". Deprecated. If the filter is called "amovie", it will select
5092 audio instead of video.
5095 Specifies how many times to read the stream in sequence.
5096 If the value is less than 1, the stream will be read again and again.
5097 Default value is "1".
5099 Note that when the movie is looped the source timestamps are not
5100 changed, so it will generate non monotonically increasing timestamps.
5103 This filter allows to overlay a second video on top of main input of
5104 a filtergraph as shown in this graph:
5106 input -----------> deltapts0 --> overlay --> output
5109 movie --> scale--> deltapts1 -------+
5112 Some examples follow.
5116 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
5117 on top of the input labelled as "in":
5119 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
5120 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
5124 Read from a video4linux2 device, and overlay it on top of the input
5127 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
5128 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
5132 Read the first video stream and the audio stream with id 0x81 from
5133 dvd.vob; the video is connected to the pad named "video" and the audio is
5134 connected to the pad named "audio":
5136 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
5140 @c man end MULTIMEDIA SOURCES