1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 In libavfilter, it is possible for filters to have multiple inputs and
8 To illustrate the sorts of things that are possible, we can
9 use a complex filter graph. For example, the following one:
12 input --> split ---------------------> overlay --> output
15 +-----> crop --> vflip -------+
18 splits the stream in two streams, sends one stream through the crop filter
19 and the vflip filter before merging it back with the other stream by
20 overlaying it on top. You can use the following command to achieve this:
23 ffmpeg -i input -vf "[in] split [T1], [T2] overlay=0:H/2 [out]; [T1] crop=iw:ih/2:0:ih/2, vflip [T2]" output
26 The result will be that in output the top half of the video is mirrored
29 Filters are loaded using the @var{-vf} or @var{-af} option passed to
30 @command{ffmpeg} or to @command{ffplay}. Filters in the same linear
31 chain are separated by commas. In our example, @var{split,
32 overlay} are in one linear chain, and @var{crop, vflip} are in
33 another. The points where the linear chains join are labeled by names
34 enclosed in square brackets. In our example, that is @var{[T1]} and
35 @var{[T2]}. The special labels @var{[in]} and @var{[out]} are the points
36 where video is input and output.
38 Some filters take in input a list of parameters: they are specified
39 after the filter name and an equal sign, and are separated from each other
42 There exist so-called @var{source filters} that do not have an
43 audio/video input, and @var{sink filters} that will not have audio/video
46 @c man end FILTERING INTRODUCTION
49 @c man begin GRAPH2DOT
51 The @file{graph2dot} program included in the FFmpeg @file{tools}
52 directory can be used to parse a filter graph description and issue a
53 corresponding textual representation in the dot language.
60 to see how to use @file{graph2dot}.
62 You can then pass the dot description to the @file{dot} program (from
63 the graphviz suite of programs) and obtain a graphical representation
66 For example the sequence of commands:
68 echo @var{GRAPH_DESCRIPTION} | \
69 tools/graph2dot -o graph.tmp && \
70 dot -Tpng graph.tmp -o graph.png && \
74 can be used to create and display an image representing the graph
75 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
76 a complete self-contained graph, with its inputs and outputs explicitly defined.
77 For example if your command line is of the form:
79 ffmpeg -i infile -vf scale=640:360 outfile
81 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
83 nullsrc,scale=640:360,nullsink
85 you may also need to set the @var{nullsrc} parameters and add a @var{format}
86 filter in order to simulate a specific input file.
90 @chapter Filtergraph description
91 @c man begin FILTERGRAPH DESCRIPTION
93 A filtergraph is a directed graph of connected filters. It can contain
94 cycles, and there can be multiple links between a pair of
95 filters. Each link has one input pad on one side connecting it to one
96 filter from which it takes its input, and one output pad on the other
97 side connecting it to the one filter accepting its output.
99 Each filter in a filtergraph is an instance of a filter class
100 registered in the application, which defines the features and the
101 number of input and output pads of the filter.
103 A filter with no input pads is called a "source", a filter with no
104 output pads is called a "sink".
106 @anchor{Filtergraph syntax}
107 @section Filtergraph syntax
109 A filtergraph can be represented using a textual representation, which is
110 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
111 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
112 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
113 @file{libavfilter/avfiltergraph.h}.
115 A filterchain consists of a sequence of connected filters, each one
116 connected to the previous one in the sequence. A filterchain is
117 represented by a list of ","-separated filter descriptions.
119 A filtergraph consists of a sequence of filterchains. A sequence of
120 filterchains is represented by a list of ";"-separated filterchain
123 A filter is represented by a string of the form:
124 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
126 @var{filter_name} is the name of the filter class of which the
127 described filter is an instance of, and has to be the name of one of
128 the filter classes registered in the program.
129 The name of the filter class is optionally followed by a string
132 @var{arguments} is a string which contains the parameters used to
133 initialize the filter instance, and are described in the filter
136 The list of arguments can be quoted using the character "'" as initial
137 and ending mark, and the character '\' for escaping the characters
138 within the quoted text; otherwise the argument string is considered
139 terminated when the next special character (belonging to the set
140 "[]=;,") is encountered.
142 The name and arguments of the filter are optionally preceded and
143 followed by a list of link labels.
144 A link label allows to name a link and associate it to a filter output
145 or input pad. The preceding labels @var{in_link_1}
146 ... @var{in_link_N}, are associated to the filter input pads,
147 the following labels @var{out_link_1} ... @var{out_link_M}, are
148 associated to the output pads.
150 When two link labels with the same name are found in the
151 filtergraph, a link between the corresponding input and output pad is
154 If an output pad is not labelled, it is linked by default to the first
155 unlabelled input pad of the next filter in the filterchain.
156 For example in the filterchain:
158 nullsrc, split[L1], [L2]overlay, nullsink
160 the split filter instance has two output pads, and the overlay filter
161 instance two input pads. The first output pad of split is labelled
162 "L1", the first input pad of overlay is labelled "L2", and the second
163 output pad of split is linked to the second input pad of overlay,
164 which are both unlabelled.
166 In a complete filterchain all the unlabelled filter input and output
167 pads must be connected. A filtergraph is considered valid if all the
168 filter input and output pads of all the filterchains are connected.
170 Libavfilter will automatically insert scale filters where format
171 conversion is required. It is possible to specify swscale flags
172 for those automatically inserted scalers by prepending
173 @code{sws_flags=@var{flags};}
174 to the filtergraph description.
176 Follows a BNF description for the filtergraph syntax:
178 @var{NAME} ::= sequence of alphanumeric characters and '_'
179 @var{LINKLABEL} ::= "[" @var{NAME} "]"
180 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
181 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
182 @var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
183 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
184 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
187 @section Notes on filtergraph escaping
189 Some filter arguments require the use of special characters, typically
190 @code{:} to separate key=value pairs in a named options list. In this
191 case the user should perform a first level escaping when specifying
192 the filter arguments. For example, consider the following literal
193 string to be embedded in the @ref{drawtext} filter arguments:
195 this is a 'string': may contain one, or more, special characters
198 Since @code{:} is special for the filter arguments syntax, it needs to
199 be escaped, so you get:
201 text=this is a \'string\'\: may contain one, or more, special characters
204 A second level of escaping is required when embedding the filter
205 arguments in a filtergraph description, in order to escape all the
206 filtergraph special characters. Thus the example above becomes:
208 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
211 Finally an additional level of escaping may be needed when writing the
212 filtergraph description in a shell command, which depends on the
213 escaping rules of the adopted shell. For example, assuming that
214 @code{\} is special and needs to be escaped with another @code{\}, the
215 previous string will finally result in:
217 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
220 Sometimes, it might be more convenient to employ quoting in place of
221 escaping. For example the string:
223 Caesar: tu quoque, Brute, fili mi
226 Can be quoted in the filter arguments as:
228 text='Caesar: tu quoque, Brute, fili mi'
231 And finally inserted in a filtergraph like:
233 drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
236 See the ``Quoting and escaping'' section in the ffmpeg-utils manual
237 for more information about the escaping and quoting rules adopted by
240 @c man end FILTERGRAPH DESCRIPTION
242 @chapter Audio Filters
243 @c man begin AUDIO FILTERS
245 When you configure your FFmpeg build, you can disable any of the
246 existing filters using @code{--disable-filters}.
247 The configure output will show the audio filters included in your
250 Below is a description of the currently available audio filters.
254 Convert the input audio format to the specified formats.
256 The filter accepts a string of the form:
257 "@var{sample_format}:@var{channel_layout}".
259 @var{sample_format} specifies the sample format, and can be a string or the
260 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
261 suffix for a planar sample format.
263 @var{channel_layout} specifies the channel layout, and can be a string
264 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
266 The special parameter "auto", signifies that the filter will
267 automatically select the output format depending on the output filter.
269 Some examples follow.
273 Convert input to float, planar, stereo:
279 Convert input to unsigned 8-bit, automatically select out channel layout:
287 Apply fade-in/out effect to input audio.
289 The filter accepts parameters as a list of @var{key}=@var{value}
290 pairs, separated by ":".
292 A description of the accepted parameters follows.
296 Specify the effect type, can be either @code{in} for fade-in, or
297 @code{out} for a fade-out effect. Default is @code{in}.
299 @item start_sample, ss
300 Specify the number of the start sample for starting to apply the fade
301 effect. Default is 0.
304 Specify the number of samples for which the fade effect has to last. At
305 the end of the fade-in effect the output audio will have the same
306 volume as the input audio, at the end of the fade-out transition
307 the output audio will be silence. Default is 44100.
310 Specify time in seconds for starting to apply the fade
311 effect. Default is 0.
312 If set this option is used instead of @var{start_sample} one.
315 Specify the number of seconds for which the fade effect has to last. At
316 the end of the fade-in effect the output audio will have the same
317 volume as the input audio, at the end of the fade-out transition
318 the output audio will be silence. Default is 0.
319 If set this option is used instead of @var{nb_samples} one.
322 Set cuve for fade transition.
324 @item @var{triangular, linear slope (default)}
326 @item @var{quarter of sine wave}
328 @item @var{half of sine wave}
330 @item @var{exponential sine wave}
332 @item @var{logarithmic}
334 @item @var{inverted parabola}
336 @item @var{quadratic}
340 @item @var{square root}
342 @item @var{cubic root}
350 Fade in first 15 seconds of audio:
356 Fade out last 25 seconds of a 900 seconds audio:
358 afade=t=out:ss=875:d=25
364 Set output format constraints for the input audio. The framework will
365 negotiate the most appropriate format to minimize conversions.
367 The filter accepts the following named parameters:
371 A comma-separated list of requested sample formats.
374 A comma-separated list of requested sample rates.
376 @item channel_layouts
377 A comma-separated list of requested channel layouts.
381 If a parameter is omitted, all values are allowed.
383 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
385 aformat='sample_fmts=u8,s16:channel_layouts=stereo'
390 Merge two or more audio streams into a single multi-channel stream.
392 The filter accepts the following named options:
397 Set the number of inputs. Default is 2.
401 If the channel layouts of the inputs are disjoint, and therefore compatible,
402 the channel layout of the output will be set accordingly and the channels
403 will be reordered as necessary. If the channel layouts of the inputs are not
404 disjoint, the output will have all the channels of the first input then all
405 the channels of the second input, in that order, and the channel layout of
406 the output will be the default value corresponding to the total number of
409 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
410 is FC+BL+BR, then the output will be in 5.1, with the channels in the
411 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
412 first input, b1 is the first channel of the second input).
414 On the other hand, if both input are in stereo, the output channels will be
415 in the default order: a1, a2, b1, b2, and the channel layout will be
416 arbitrarily set to 4.0, which may or may not be the expected value.
418 All inputs must have the same sample rate, and format.
420 If inputs do not have the same duration, the output will stop with the
423 Example: merge two mono files into a stereo stream:
425 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
428 Example: multiple merges:
431 amovie=input.mkv:si=0 [a0];
432 amovie=input.mkv:si=1 [a1];
433 amovie=input.mkv:si=2 [a2];
434 amovie=input.mkv:si=3 [a3];
435 amovie=input.mkv:si=4 [a4];
436 amovie=input.mkv:si=5 [a5];
437 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
442 Mixes multiple audio inputs into a single output.
446 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
448 will mix 3 input audio streams to a single output with the same duration as the
449 first input and a dropout transition time of 3 seconds.
451 The filter accepts the following named parameters:
455 Number of inputs. If unspecified, it defaults to 2.
458 How to determine the end-of-stream.
462 Duration of longest input. (default)
465 Duration of shortest input.
468 Duration of first input.
472 @item dropout_transition
473 Transition time, in seconds, for volume renormalization when an input
474 stream ends. The default value is 2 seconds.
480 Pass the audio source unchanged to the output.
484 Pad the end of a audio stream with silence, this can be used together with
485 -shortest to extend audio streams to the same length as the video stream.
490 Resample the input audio to the specified parameters, using the
491 libswresample library. If none are specified then the filter will
492 automatically convert between its input and output.
494 This filter is also able to stretch/squeeze the audio data to make it match
495 the timestamps or to inject silence / cut out audio to make it match the
496 timestamps, do a combination of both or do neither.
498 The filter accepts the syntax
499 [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate}
500 expresses a sample rate and @var{resampler_options} is a list of
501 @var{key}=@var{value} pairs, separated by ":". See the
502 ffmpeg-resampler manual for the complete list of supported options.
504 For example, to resample the input audio to 44100Hz:
509 To stretch/squeeze samples to the given timestamps, with a maximum of 1000
510 samples per second compensation:
515 @section asetnsamples
517 Set the number of samples per each output audio frame.
519 The last output packet may contain a different number of samples, as
520 the filter will flush all the remaining samples when the input audio
523 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
528 @item nb_out_samples, n
529 Set the number of frames per each output audio frame. The number is
530 intended as the number of samples @emph{per each channel}.
531 Default value is 1024.
534 If set to 1, the filter will pad the last audio frame with zeroes, so
535 that the last frame will contain the same number of samples as the
536 previous ones. Default value is 1.
539 For example, to set the number of per-frame samples to 1234 and
540 disable padding for the last frame, use:
542 asetnsamples=n=1234:p=0
547 Show a line containing various information for each input audio frame.
548 The input audio is not modified.
550 The shown line contains a sequence of key/value pairs of the form
551 @var{key}:@var{value}.
553 A description of each shown parameter follows:
557 sequential number of the input frame, starting from 0
560 Presentation timestamp of the input frame, in time base units; the time base
561 depends on the filter input pad, and is usually 1/@var{sample_rate}.
564 presentation timestamp of the input frame in seconds
567 position of the frame in the input stream, -1 if this information in
568 unavailable and/or meaningless (for example in case of synthetic audio)
577 sample rate for the audio frame
580 number of samples (per channel) in the frame
583 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
584 the data is treated as if all the planes were concatenated.
586 @item plane_checksums
587 A list of Adler-32 checksums for each data plane.
592 Split input audio into several identical outputs.
594 The filter accepts a single parameter which specifies the number of outputs. If
595 unspecified, it defaults to 2.
599 [in] asplit [out0][out1]
602 will create two separate outputs from the same input.
604 To create 3 or more outputs, you need to specify the number of
607 [in] asplit=3 [out0][out1][out2]
611 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
613 will create 5 copies of the input audio.
618 Forward two audio streams and control the order the buffers are forwarded.
620 The argument to the filter is an expression deciding which stream should be
621 forwarded next: if the result is negative, the first stream is forwarded; if
622 the result is positive or zero, the second stream is forwarded. It can use
623 the following variables:
627 number of buffers forwarded so far on each stream
629 number of samples forwarded so far on each stream
631 current timestamp of each stream
634 The default value is @code{t1-t2}, which means to always forward the stream
635 that has a smaller timestamp.
637 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
638 input, while avoiding too much of a desynchronization:
640 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
641 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
649 The filter accepts exactly one parameter, the audio tempo. If not
650 specified then the filter will assume nominal 1.0 tempo. Tempo must
651 be in the [0.5, 2.0] range.
653 For example, to slow down audio to 80% tempo:
658 For example, to speed up audio to 125% tempo:
665 Make audio easier to listen to on headphones.
667 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
668 so that when listened to on headphones the stereo image is moved from
669 inside your head (standard for headphones) to outside and in front of
670 the listener (standard for speakers).
676 Mix channels with specific gain levels. The filter accepts the output
677 channel layout followed by a set of channels definitions.
679 This filter is also designed to remap efficiently the channels of an audio
682 The filter accepts parameters of the form:
683 "@var{l}:@var{outdef}:@var{outdef}:..."
687 output channel layout or number of channels
690 output channel specification, of the form:
691 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
694 output channel to define, either a channel name (FL, FR, etc.) or a channel
695 number (c0, c1, etc.)
698 multiplicative coefficient for the channel, 1 leaving the volume unchanged
701 input channel to use, see out_name for details; it is not possible to mix
702 named and numbered input channels
705 If the `=' in a channel specification is replaced by `<', then the gains for
706 that specification will be renormalized so that the total is 1, thus
707 avoiding clipping noise.
709 @subsection Mixing examples
711 For example, if you want to down-mix from stereo to mono, but with a bigger
712 factor for the left channel:
714 pan=1:c0=0.9*c0+0.1*c1
717 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
720 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
723 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
724 that should be preferred (see "-ac" option) unless you have very specific
727 @subsection Remapping examples
729 The channel remapping will be effective if, and only if:
732 @item gain coefficients are zeroes or ones,
733 @item only one input per channel output,
736 If all these conditions are satisfied, the filter will notify the user ("Pure
737 channel mapping detected"), and use an optimized and lossless method to do the
740 For example, if you have a 5.1 source and want a stereo audio stream by
741 dropping the extra channels:
743 pan="stereo: c0=FL : c1=FR"
746 Given the same source, you can also switch front left and front right channels
747 and keep the input channel layout:
749 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
752 If the input is a stereo audio stream, you can mute the front left channel (and
753 still keep the stereo channel layout) with:
758 Still with a stereo audio stream input, you can copy the right channel in both
759 front left and right:
761 pan="stereo: c0=FR : c1=FR"
764 @section silencedetect
766 Detect silence in an audio stream.
768 This filter logs a message when it detects that the input audio volume is less
769 or equal to a noise tolerance value for a duration greater or equal to the
770 minimum detected noise duration.
772 The printed times and duration are expressed in seconds.
776 Set silence duration until notification (default is 2 seconds).
779 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
780 specified value) or amplitude ratio. Default is -60dB, or 0.001.
783 Detect 5 seconds of silence with -50dB noise tolerance:
785 silencedetect=n=-50dB:d=5
788 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
789 tolerance in @file{silence.mp3}:
791 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
795 Synchronize audio data with timestamps by squeezing/stretching it and/or
796 dropping samples/adding silence when needed.
798 This filter is not built by default, please use @ref{aresample} to do squeezing/stretching.
800 The filter accepts the following named parameters:
804 Enable stretching/squeezing the data to make it match the timestamps. Disabled
805 by default. When disabled, time gaps are covered with silence.
808 Minimum difference between timestamps and audio data (in seconds) to trigger
809 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
810 this filter, try setting this parameter to 0.
813 Maximum compensation in samples per second. Relevant only with compensate=1.
817 Assume the first pts should be this value. The time base is 1 / sample rate.
818 This allows for padding/trimming at the start of stream. By default, no
819 assumption is made about the first frame's expected pts, so no padding or
820 trimming is done. For example, this could be set to 0 to pad the beginning with
821 silence if an audio stream starts after the video stream or to trim any samples
822 with a negative pts due to encoder delay.
826 @section channelsplit
827 Split each channel in input audio stream into a separate output stream.
829 This filter accepts the following named parameters:
832 Channel layout of the input stream. Default is "stereo".
835 For example, assuming a stereo input MP3 file
837 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
839 will create an output Matroska file with two audio streams, one containing only
840 the left channel and the other the right channel.
842 To split a 5.1 WAV file into per-channel files
844 ffmpeg -i in.wav -filter_complex
845 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
846 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
847 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
852 Remap input channels to new locations.
854 This filter accepts the following named parameters:
857 Channel layout of the output stream.
860 Map channels from input to output. The argument is a comma-separated list of
861 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
862 @var{in_channel} form. @var{in_channel} can be either the name of the input
863 channel (e.g. FL for front left) or its index in the input channel layout.
864 @var{out_channel} is the name of the output channel or its index in the output
865 channel layout. If @var{out_channel} is not given then it is implicitly an
866 index, starting with zero and increasing by one for each mapping.
869 If no mapping is present, the filter will implicitly map input channels to
870 output channels preserving index.
872 For example, assuming a 5.1+downmix input MOV file
874 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
876 will create an output WAV file tagged as stereo from the downmix channels of
879 To fix a 5.1 WAV improperly encoded in AAC's native channel order
881 ffmpeg -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
885 Join multiple input streams into one multi-channel stream.
887 The filter accepts the following named parameters:
891 Number of input streams. Defaults to 2.
894 Desired output channel layout. Defaults to stereo.
897 Map channels from inputs to output. The argument is a comma-separated list of
898 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
899 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
900 can be either the name of the input channel (e.g. FL for front left) or its
901 index in the specified input stream. @var{out_channel} is the name of the output
905 The filter will attempt to guess the mappings when those are not specified
906 explicitly. It does so by first trying to find an unused matching input channel
907 and if that fails it picks the first unused input channel.
909 E.g. to join 3 inputs (with properly set channel layouts)
911 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
914 To build a 5.1 output from 6 single-channel streams:
916 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
917 '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'
922 Convert the audio sample format, sample rate and channel layout. This filter is
923 not meant to be used directly.
927 Adjust the input audio volume.
929 The filter accepts the following named parameters. If the key of the
930 first options is omitted, the arguments are interpreted according to
931 the following syntax:
933 volume=@var{volume}:@var{precision}
939 Expresses how the audio volume will be increased or decreased.
941 Output values are clipped to the maximum value.
943 The output audio volume is given by the relation:
945 @var{output_volume} = @var{volume} * @var{input_volume}
948 Default value for @var{volume} is 1.0.
951 Set the mathematical precision.
953 This determines which input sample formats will be allowed, which affects the
954 precision of the volume scaling.
958 8-bit fixed-point; limits input sample format to U8, S16, and S32.
960 32-bit floating-point; limits input sample format to FLT. (default)
962 64-bit floating-point; limits input sample format to DBL.
970 Halve the input audio volume:
974 volume=volume=-6.0206dB
977 In all the above example the named key for @option{volume} can be
978 omitted, for example like in:
984 Increase input audio power by 6 decibels using fixed-point precision:
986 volume=volume=6dB:precision=fixed
990 @section volumedetect
992 Detect the volume of the input video.
994 The filter has no parameters. The input is not modified. Statistics about
995 the volume will be printed in the log when the input stream end is reached.
997 In particular it will show the mean volume (root mean square), maximum
998 volume (on a per-sample basis), and the beginning of an histogram of the
999 registered volume values (from the maximum value to a cumulated 1/1000 of
1002 All volumes are in decibels relative to the maximum PCM value.
1004 Here is an excerpt of the output:
1006 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
1007 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
1008 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
1009 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
1010 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
1011 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
1012 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
1013 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
1014 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
1020 The mean square energy is approximately -27 dB, or 10^-2.7.
1022 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
1024 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
1027 In other words, raising the volume by +4 dB does not cause any clipping,
1028 raising it by +5 dB causes clipping for 6 samples, etc.
1030 @c man end AUDIO FILTERS
1032 @chapter Audio Sources
1033 @c man begin AUDIO SOURCES
1035 Below is a description of the currently available audio sources.
1039 Buffer audio frames, and make them available to the filter chain.
1041 This source is mainly intended for a programmatic use, in particular
1042 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1044 It accepts the following mandatory parameters:
1045 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
1050 The sample rate of the incoming audio buffers.
1053 The sample format of the incoming audio buffers.
1054 Either a sample format name or its corresponging integer representation from
1055 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1057 @item channel_layout
1058 The channel layout of the incoming audio buffers.
1059 Either a channel layout name from channel_layout_map in
1060 @file{libavutil/channel_layout.c} or its corresponding integer representation
1061 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1067 abuffer=44100:s16p:stereo
1070 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1071 Since the sample format with name "s16p" corresponds to the number
1072 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1080 Generate an audio signal specified by an expression.
1082 This source accepts in input one or more expressions (one for each
1083 channel), which are evaluated and used to generate a corresponding
1086 It accepts the syntax: @var{exprs}[::@var{options}].
1087 @var{exprs} is a list of expressions separated by ":", one for each
1088 separate channel. In case the @var{channel_layout} is not
1089 specified, the selected channel layout depends on the number of
1090 provided expressions.
1092 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1095 The description of the accepted options follows.
1099 @item channel_layout, c
1100 Set the channel layout. The number of channels in the specified layout
1101 must be equal to the number of specified expressions.
1104 Set the minimum duration of the sourced audio. See the function
1105 @code{av_parse_time()} for the accepted format.
1106 Note that the resulting duration may be greater than the specified
1107 duration, as the generated audio is always cut at the end of a
1110 If not specified, or the expressed duration is negative, the audio is
1111 supposed to be generated forever.
1114 Set the number of samples per channel per each output frame,
1117 @item sample_rate, s
1118 Specify the sample rate, default to 44100.
1121 Each expression in @var{exprs} can contain the following constants:
1125 number of the evaluated sample, starting from 0
1128 time of the evaluated sample expressed in seconds, starting from 0
1135 @subsection Examples
1147 Generate a sin signal with frequency of 440 Hz, set sample rate to
1150 aevalsrc="sin(440*2*PI*t)::s=8000"
1154 Generate a two channels signal, specify the channel layout (Front
1155 Center + Back Center) explicitly:
1157 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1161 Generate white noise:
1163 aevalsrc="-2+random(0)"
1167 Generate an amplitude modulated signal:
1169 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1173 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1175 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1182 Null audio source, return unprocessed audio frames. It is mainly useful
1183 as a template and to be employed in analysis / debugging tools, or as
1184 the source for filters which ignore the input data (for example the sox
1187 It accepts an optional sequence of @var{key}=@var{value} pairs,
1190 The description of the accepted options follows.
1194 @item sample_rate, s
1195 Specify the sample rate, and defaults to 44100.
1197 @item channel_layout, cl
1199 Specify the channel layout, and can be either an integer or a string
1200 representing a channel layout. The default value of @var{channel_layout}
1203 Check the channel_layout_map definition in
1204 @file{libavutil/channel_layout.c} for the mapping between strings and
1205 channel layout values.
1208 Set the number of samples per requested frames.
1212 Follow some examples:
1214 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1215 anullsrc=r=48000:cl=4
1218 anullsrc=r=48000:cl=mono
1222 Buffer audio frames, and make them available to the filter chain.
1224 This source is not intended to be part of user-supplied graph descriptions but
1225 for insertion by calling programs through the interface defined in
1226 @file{libavfilter/buffersrc.h}.
1228 It accepts the following named parameters:
1232 Timebase which will be used for timestamps of submitted frames. It must be
1233 either a floating-point number or in @var{numerator}/@var{denominator} form.
1239 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1241 @item channel_layout
1242 Channel layout of the audio data, in the form that can be accepted by
1243 @code{av_get_channel_layout()}.
1246 All the parameters need to be explicitly defined.
1250 Synthesize a voice utterance using the libflite library.
1252 To enable compilation of this filter you need to configure FFmpeg with
1253 @code{--enable-libflite}.
1255 Note that the flite library is not thread-safe.
1257 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1260 The description of the accepted parameters follows.
1265 If set to 1, list the names of the available voices and exit
1266 immediately. Default value is 0.
1269 Set the maximum number of samples per frame. Default value is 512.
1272 Set the filename containing the text to speak.
1275 Set the text to speak.
1278 Set the voice to use for the speech synthesis. Default value is
1279 @code{kal}. See also the @var{list_voices} option.
1282 @subsection Examples
1286 Read from file @file{speech.txt}, and synthetize the text using the
1287 standard flite voice:
1289 flite=textfile=speech.txt
1293 Read the specified text selecting the @code{slt} voice:
1295 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1299 Input text to ffmpeg:
1301 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1305 Make @file{ffplay} speak the specified text, using @code{flite} and
1306 the @code{lavfi} device:
1308 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1312 For more information about libflite, check:
1313 @url{http://www.speech.cs.cmu.edu/flite/}
1315 @c man end AUDIO SOURCES
1317 @chapter Audio Sinks
1318 @c man begin AUDIO SINKS
1320 Below is a description of the currently available audio sinks.
1322 @section abuffersink
1324 Buffer audio frames, and make them available to the end of filter chain.
1326 This sink is mainly intended for programmatic use, in particular
1327 through the interface defined in @file{libavfilter/buffersink.h}.
1329 It requires a pointer to an AVABufferSinkContext structure, which
1330 defines the incoming buffers' formats, to be passed as the opaque
1331 parameter to @code{avfilter_init_filter} for initialization.
1335 Null audio sink, do absolutely nothing with the input audio. It is
1336 mainly useful as a template and to be employed in analysis / debugging
1339 @section abuffersink
1340 This sink is intended for programmatic use. Frames that arrive on this sink can
1341 be retrieved by the calling program using the interface defined in
1342 @file{libavfilter/buffersink.h}.
1344 This filter accepts no parameters.
1346 @c man end AUDIO SINKS
1348 @chapter Video Filters
1349 @c man begin VIDEO FILTERS
1351 When you configure your FFmpeg build, you can disable any of the
1352 existing filters using @code{--disable-filters}.
1353 The configure output will show the video filters included in your
1356 Below is a description of the currently available video filters.
1358 @section alphaextract
1360 Extract the alpha component from the input as a grayscale video. This
1361 is especially useful with the @var{alphamerge} filter.
1365 Add or replace the alpha component of the primary input with the
1366 grayscale value of a second input. This is intended for use with
1367 @var{alphaextract} to allow the transmission or storage of frame
1368 sequences that have alpha in a format that doesn't support an alpha
1371 For example, to reconstruct full frames from a normal YUV-encoded video
1372 and a separate video created with @var{alphaextract}, you might use:
1374 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1377 Since this filter is designed for reconstruction, it operates on frame
1378 sequences without considering timestamps, and terminates when either
1379 input reaches end of stream. This will cause problems if your encoding
1380 pipeline drops frames. If you're trying to apply an image as an
1381 overlay to a video stream, consider the @var{overlay} filter instead.
1385 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1386 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1387 Substation Alpha) subtitles files.
1391 Compute the bounding box for the non-black pixels in the input frame
1394 This filter computes the bounding box containing all the pixels with a
1395 luminance value greater than the minimum allowed value.
1396 The parameters describing the bounding box are printed on the filter
1399 @section blackdetect
1401 Detect video intervals that are (almost) completely black. Can be
1402 useful to detect chapter transitions, commercials, or invalid
1403 recordings. Output lines contains the time for the start, end and
1404 duration of the detected black interval expressed in seconds.
1406 In order to display the output lines, you need to set the loglevel at
1407 least to the AV_LOG_INFO value.
1409 This filter accepts a list of options in the form of
1410 @var{key}=@var{value} pairs separated by ":". A description of the
1411 accepted options follows.
1414 @item black_min_duration, d
1415 Set the minimum detected black duration expressed in seconds. It must
1416 be a non-negative floating point number.
1418 Default value is 2.0.
1420 @item picture_black_ratio_th, pic_th
1421 Set the threshold for considering a picture "black".
1422 Express the minimum value for the ratio:
1424 @var{nb_black_pixels} / @var{nb_pixels}
1427 for which a picture is considered black.
1428 Default value is 0.98.
1430 @item pixel_black_th, pix_th
1431 Set the threshold for considering a pixel "black".
1433 The threshold expresses the maximum pixel luminance value for which a
1434 pixel is considered "black". The provided value is scaled according to
1435 the following equation:
1437 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1440 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1441 the input video format, the range is [0-255] for YUV full-range
1442 formats and [16-235] for YUV non full-range formats.
1444 Default value is 0.10.
1447 The following example sets the maximum pixel threshold to the minimum
1448 value, and detects only black intervals of 2 or more seconds:
1450 blackdetect=d=2:pix_th=0.00
1455 Detect frames that are (almost) completely black. Can be useful to
1456 detect chapter transitions or commercials. Output lines consist of
1457 the frame number of the detected frame, the percentage of blackness,
1458 the position in the file if known or -1 and the timestamp in seconds.
1460 In order to display the output lines, you need to set the loglevel at
1461 least to the AV_LOG_INFO value.
1463 The filter accepts the syntax:
1465 blackframe[=@var{amount}:[@var{threshold}]]
1468 @var{amount} is the percentage of the pixels that have to be below the
1469 threshold, and defaults to 98.
1471 @var{threshold} is the threshold below which a pixel value is
1472 considered black, and defaults to 32.
1476 Apply boxblur algorithm to the input video.
1478 This filter accepts the parameters:
1479 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
1481 Chroma and alpha parameters are optional, if not specified they default
1482 to the corresponding values set for @var{luma_radius} and
1485 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
1486 the radius in pixels of the box used for blurring the corresponding
1487 input plane. They are expressions, and can contain the following
1491 the input width and height in pixels
1494 the input chroma image width and height in pixels
1497 horizontal and vertical chroma subsample values. For example for the
1498 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1501 The radius must be a non-negative number, and must not be greater than
1502 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
1503 and of @code{min(cw,ch)/2} for the chroma planes.
1505 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
1506 how many times the boxblur filter is applied to the corresponding
1509 Some examples follow:
1514 Apply a boxblur filter with luma, chroma, and alpha radius
1521 Set luma radius to 2, alpha and chroma radius to 0
1527 Set luma and chroma radius to a fraction of the video dimension
1529 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
1534 @section colormatrix
1536 The colormatrix filter allows conversion between any of the following color
1537 space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m})
1538 and FCC (@var{fcc}).
1540 The syntax of the parameters is @var{source}:@var{destination}:
1543 colormatrix=bt601:smpte240m
1548 Copy the input source unchanged to the output. Mainly useful for
1553 Crop the input video.
1555 This filter accepts a list of @var{key}=@var{value} pairs as argument,
1556 separated by ':'. If the key of the first options is omitted, the
1557 arguments are interpreted according to the syntax
1558 @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}.
1560 A description of the accepted options follows:
1563 Set the crop area width. It defaults to @code{iw}.
1564 This expression is evaluated only once during the filter
1568 Set the crop area width. It defaults to @code{ih}.
1569 This expression is evaluated only once during the filter
1573 Set the expression for the x top-left coordinate of the cropped area.
1574 It defaults to @code{(in_w-out_w)/2}.
1575 This expression is evaluated per-frame.
1578 Set the expression for the y top-left coordinate of the cropped area.
1579 It defaults to @code{(in_h-out_h)/2}.
1580 This expression is evaluated per-frame.
1583 If set to 1 will force the output display aspect ratio
1584 to be the same of the input, by changing the output sample aspect
1585 ratio. It defaults to 0.
1588 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
1589 expressions containing the following constants:
1593 the computed values for @var{x} and @var{y}. They are evaluated for
1597 the input width and height
1600 same as @var{in_w} and @var{in_h}
1603 the output (cropped) width and height
1606 same as @var{out_w} and @var{out_h}
1609 same as @var{iw} / @var{ih}
1612 input sample aspect ratio
1615 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1618 horizontal and vertical chroma subsample values. For example for the
1619 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1622 the number of input frame, starting from 0
1625 the position in the file of the input frame, NAN if unknown
1628 timestamp expressed in seconds, NAN if the input timestamp is unknown
1632 The expression for @var{out_w} may depend on the value of @var{out_h},
1633 and the expression for @var{out_h} may depend on @var{out_w}, but they
1634 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
1635 evaluated after @var{out_w} and @var{out_h}.
1637 The @var{x} and @var{y} parameters specify the expressions for the
1638 position of the top-left corner of the output (non-cropped) area. They
1639 are evaluated for each frame. If the evaluated value is not valid, it
1640 is approximated to the nearest valid value.
1642 The expression for @var{x} may depend on @var{y}, and the expression
1643 for @var{y} may depend on @var{x}.
1645 @subsection Examples
1648 Crop area with size 100x100 at position (12,34).
1653 Using named options, the example above becomes:
1655 crop=w=100:h=100:x=12:y=34
1659 Crop the central input area with size 100x100:
1665 Crop the central input area with size 2/3 of the input video:
1667 crop=2/3*in_w:2/3*in_h
1671 Crop the input video central square:
1677 Delimit the rectangle with the top-left corner placed at position
1678 100:100 and the right-bottom corner corresponding to the right-bottom
1679 corner of the input image:
1681 crop=in_w-100:in_h-100:100:100
1685 Crop 10 pixels from the left and right borders, and 20 pixels from
1686 the top and bottom borders
1688 crop=in_w-2*10:in_h-2*20
1692 Keep only the bottom right quarter of the input image:
1694 crop=in_w/2:in_h/2:in_w/2:in_h/2
1698 Crop height for getting Greek harmony:
1700 crop=in_w:1/PHI*in_w
1704 Appply trembling effect:
1706 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)
1710 Apply erratic camera effect depending on timestamp:
1712 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)"
1716 Set x depending on the value of y:
1718 crop=in_w/2:in_h/2:y:10+10*sin(n/10)
1724 Auto-detect crop size.
1726 Calculate necessary cropping parameters and prints the recommended
1727 parameters through the logging system. The detected dimensions
1728 correspond to the non-black area of the input video.
1730 It accepts the syntax:
1732 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
1738 Threshold, which can be optionally specified from nothing (0) to
1739 everything (255), defaults to 24.
1742 Value which the width/height should be divisible by, defaults to
1743 16. The offset is automatically adjusted to center the video. Use 2 to
1744 get only even dimensions (needed for 4:2:2 video). 16 is best when
1745 encoding to most video codecs.
1748 Counter that determines after how many frames cropdetect will reset
1749 the previously detected largest video area and start over to detect
1750 the current optimal crop area. Defaults to 0.
1752 This can be useful when channel logos distort the video area. 0
1753 indicates never reset and return the largest area encountered during
1759 This filter drops frames that do not differ greatly from the previous
1760 frame in order to reduce framerate. The main use of this filter is
1761 for very-low-bitrate encoding (e.g. streaming over dialup modem), but
1762 it could in theory be used for fixing movies that were
1763 inverse-telecined incorrectly.
1765 It accepts the following parameters:
1766 @var{max}:@var{hi}:@var{lo}:@var{frac}.
1771 Set the maximum number of consecutive frames which can be dropped (if
1772 positive), or the minimum interval between dropped frames (if
1773 negative). If the value is 0, the frame is dropped unregarding the
1774 number of previous sequentially dropped frames.
1779 Set the dropping threshold values.
1781 Values for @var{hi} and @var{lo} are for 8x8 pixel blocks and
1782 represent actual pixel value differences, so a threshold of 64
1783 corresponds to 1 unit of difference for each pixel, or the same spread
1784 out differently over the block.
1786 A frame is a candidate for dropping if no 8x8 blocks differ by more
1787 than a threshold of @var{hi}, and if no more than @var{frac} blocks (1
1788 meaning the whole image) differ by more than a threshold of @var{lo}.
1790 Default value for @var{hi} is 64*12, default value for @var{lo} is
1791 64*5, and default value for @var{frac} is 0.33.
1796 Suppress a TV station logo by a simple interpolation of the surrounding
1797 pixels. Just set a rectangle covering the logo and watch it disappear
1798 (and sometimes something even uglier appear - your mileage may vary).
1800 The filter accepts parameters as a string of the form
1801 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
1802 @var{key}=@var{value} pairs, separated by ":".
1804 The description of the accepted parameters follows.
1809 Specify the top left corner coordinates of the logo. They must be
1813 Specify the width and height of the logo to clear. They must be
1817 Specify the thickness of the fuzzy edge of the rectangle (added to
1818 @var{w} and @var{h}). The default value is 4.
1821 When set to 1, a green rectangle is drawn on the screen to simplify
1822 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1823 @var{band} is set to 4. The default value is 0.
1827 Some examples follow.
1832 Set a rectangle covering the area with top left corner coordinates 0,0
1833 and size 100x77, setting a band of size 10:
1835 delogo=0:0:100:77:10
1839 As the previous example, but use named options:
1841 delogo=x=0:y=0:w=100:h=77:band=10
1848 Attempt to fix small changes in horizontal and/or vertical shift. This
1849 filter helps remove camera shake from hand-holding a camera, bumping a
1850 tripod, moving on a vehicle, etc.
1852 The filter accepts parameters as a string of the form
1853 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
1855 A description of the accepted parameters follows.
1860 Specify a rectangular area where to limit the search for motion
1862 If desired the search for motion vectors can be limited to a
1863 rectangular area of the frame defined by its top left corner, width
1864 and height. These parameters have the same meaning as the drawbox
1865 filter which can be used to visualise the position of the bounding
1868 This is useful when simultaneous movement of subjects within the frame
1869 might be confused for camera motion by the motion vector search.
1871 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
1872 then the full frame is used. This allows later options to be set
1873 without specifying the bounding box for the motion vector search.
1875 Default - search the whole frame.
1878 Specify the maximum extent of movement in x and y directions in the
1879 range 0-64 pixels. Default 16.
1882 Specify how to generate pixels to fill blanks at the edge of the
1883 frame. An integer from 0 to 3 as follows:
1886 Fill zeroes at blank locations
1888 Original image at blank locations
1890 Extruded edge value at blank locations
1892 Mirrored edge at blank locations
1895 The default setting is mirror edge at blank locations.
1898 Specify the blocksize to use for motion search. Range 4-128 pixels,
1902 Specify the contrast threshold for blocks. Only blocks with more than
1903 the specified contrast (difference between darkest and lightest
1904 pixels) will be considered. Range 1-255, default 125.
1907 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
1908 search. Default - exhaustive search.
1911 If set then a detailed log of the motion search is written to the
1918 Draw a colored box on the input image.
1920 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1923 The description of the accepted parameters follows.
1927 Specify the top left corner coordinates of the box. Default to 0.
1931 Specify the width and height of the box, if 0 they are interpreted as
1932 the input width and height. Default to 0.
1935 Specify the color of the box to write, it can be the name of a color
1936 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
1937 value @code{invert} is used, the box edge color is the same as the
1938 video with inverted luma.
1941 Set the thickness of the box edge. Default value is @code{4}.
1944 If the key of the first options is omitted, the arguments are
1945 interpreted according to the syntax
1946 @var{x}:@var{y}:@var{width}:@var{height}:@var{color}:@var{thickness}.
1948 Some examples follow:
1951 Draw a black box around the edge of the input image:
1957 Draw a box with color red and an opacity of 50%:
1959 drawbox=10:20:200:60:red@@0.5
1962 The previous example can be specified as:
1964 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
1968 Fill the box with pink color:
1970 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
1977 Draw text string or text from specified file on top of video using the
1978 libfreetype library.
1980 To enable compilation of this filter you need to configure FFmpeg with
1981 @code{--enable-libfreetype}.
1985 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1988 The description of the accepted parameters follows.
1993 Used to draw a box around text using background color.
1994 Value should be either 1 (enable) or 0 (disable).
1995 The default value of @var{box} is 0.
1998 The color to be used for drawing box around text.
1999 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
2000 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2001 The default value of @var{boxcolor} is "white".
2004 Set an expression which specifies if the text should be drawn. If the
2005 expression evaluates to 0, the text is not drawn. This is useful for
2006 specifying that the text should be drawn only when specific conditions
2009 Default value is "1".
2011 See below for the list of accepted constants and functions.
2014 Select how the @var{text} is expanded. Can be either @code{none},
2015 @code{strftime} (default for compatibity reasons but deprecated) or
2016 @code{normal}. See the @ref{drawtext_expansion, Text expansion} section
2020 If true, check and fix text coords to avoid clipping.
2023 The color to be used for drawing fonts.
2024 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
2025 (e.g. "0xff000033"), possibly followed by an alpha specifier.
2026 The default value of @var{fontcolor} is "black".
2029 The font file to be used for drawing text. Path must be included.
2030 This parameter is mandatory.
2033 The font size to be used for drawing text.
2034 The default value of @var{fontsize} is 16.
2037 Flags to be used for loading the fonts.
2039 The flags map the corresponding flags supported by libfreetype, and are
2040 a combination of the following values:
2047 @item vertical_layout
2048 @item force_autohint
2051 @item ignore_global_advance_width
2053 @item ignore_transform
2060 Default value is "render".
2062 For more information consult the documentation for the FT_LOAD_*
2066 The color to be used for drawing a shadow behind the drawn text. It
2067 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
2068 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
2069 The default value of @var{shadowcolor} is "black".
2071 @item shadowx, shadowy
2072 The x and y offsets for the text shadow position with respect to the
2073 position of the text. They can be either positive or negative
2074 values. Default value for both is "0".
2077 The size in number of spaces to use for rendering the tab.
2081 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
2082 format. It can be used with or without text parameter. @var{timecode_rate}
2083 option must be specified.
2085 @item timecode_rate, rate, r
2086 Set the timecode frame rate (timecode only).
2089 The text string to be drawn. The text must be a sequence of UTF-8
2091 This parameter is mandatory if no file is specified with the parameter
2095 A text file containing text to be drawn. The text must be a sequence
2096 of UTF-8 encoded characters.
2098 This parameter is mandatory if no text string is specified with the
2099 parameter @var{text}.
2101 If both @var{text} and @var{textfile} are specified, an error is thrown.
2104 If set to 1, the @var{textfile} will be reloaded before each frame.
2105 Be sure to update it atomically, or it may be read partially, or even fail.
2108 The expressions which specify the offsets where text will be drawn
2109 within the video frame. They are relative to the top/left border of the
2112 The default value of @var{x} and @var{y} is "0".
2114 See below for the list of accepted constants and functions.
2117 The parameters for @var{x} and @var{y} are expressions containing the
2118 following constants and functions:
2122 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2125 horizontal and vertical chroma subsample values. For example for the
2126 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2129 the height of each text line
2137 @item max_glyph_a, ascent
2138 the maximum distance from the baseline to the highest/upper grid
2139 coordinate used to place a glyph outline point, for all the rendered
2141 It is a positive value, due to the grid's orientation with the Y axis
2144 @item max_glyph_d, descent
2145 the maximum distance from the baseline to the lowest grid coordinate
2146 used to place a glyph outline point, for all the rendered glyphs.
2147 This is a negative value, due to the grid's orientation, with the Y axis
2151 maximum glyph height, that is the maximum height for all the glyphs
2152 contained in the rendered text, it is equivalent to @var{ascent} -
2156 maximum glyph width, that is the maximum width for all the glyphs
2157 contained in the rendered text
2160 the number of input frame, starting from 0
2162 @item rand(min, max)
2163 return a random number included between @var{min} and @var{max}
2166 input sample aspect ratio
2169 timestamp expressed in seconds, NAN if the input timestamp is unknown
2172 the height of the rendered text
2175 the width of the rendered text
2178 the x and y offset coordinates where the text is drawn.
2180 These parameters allow the @var{x} and @var{y} expressions to refer
2181 each other, so you can for example specify @code{y=x/dar}.
2184 If libavfilter was built with @code{--enable-fontconfig}, then
2185 @option{fontfile} can be a fontconfig pattern or omitted.
2187 @anchor{drawtext_expansion}
2188 @subsection Text expansion
2190 If @option{expansion} is set to @code{strftime} (which is the default for
2191 now), the filter recognizes strftime() sequences in the provided text and
2192 expands them accordingly. Check the documentation of strftime(). This
2193 feature is deprecated.
2195 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2197 If @option{expansion} is set to @code{normal} (which will be the default),
2198 the following expansion mechanism is used.
2200 The backslash character '\', followed by any character, always expands to
2201 the second character.
2203 Sequence of the form @code{%@{...@}} are expanded. The text between the
2204 braces is a function name, possibly followed by arguments separated by ':'.
2205 If the arguments contain special characters or delimiters (':' or '@}'),
2206 they should be escaped.
2208 Note that they probably must also be escaped as the value for the
2209 @option{text} option in the filter argument string and as the filter
2210 argument in the filter graph description, and possibly also for the shell,
2211 that makes up to four levels of escaping; using a text file avoids these
2214 The following functions are available:
2219 The expression evaluation result.
2221 It must take one argument specifying the expression to be evaluated,
2222 which accepts the same constants and functions as the @var{x} and
2223 @var{y} values. Note that not all constants should be used, for
2224 example the text size is not known when evaluating the expression, so
2225 the constants @var{text_w} and @var{text_h} will have an undefined
2229 The time at which the filter is running, expressed in UTC.
2230 It can accept an argument: a strftime() format string.
2233 The time at which the filter is running, expressed in the local time zone.
2234 It can accept an argument: a strftime() format string.
2237 The frame number, starting from 0.
2240 The timestamp of the current frame, in seconds, with microsecond accuracy.
2244 @subsection Examples
2246 Some examples follow.
2251 Draw "Test Text" with font FreeSerif, using the default values for the
2252 optional parameters.
2255 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2259 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2260 and y=50 (counting from the top-left corner of the screen), text is
2261 yellow with a red box around it. Both the text and the box have an
2265 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2266 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2269 Note that the double quotes are not necessary if spaces are not used
2270 within the parameter list.
2273 Show the text at the center of the video frame:
2275 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2279 Show a text line sliding from right to left in the last row of the video
2280 frame. The file @file{LONG_LINE} is assumed to contain a single line
2283 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2287 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2289 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2293 Draw a single green letter "g", at the center of the input video.
2294 The glyph baseline is placed at half screen height.
2296 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2300 Show text for 1 second every 3 seconds:
2302 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2306 Use fontconfig to set the font. Note that the colons need to be escaped.
2308 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2312 Print the date of a real-time encoding (see strftime(3)):
2314 drawtext='fontfile=FreeSans.ttf:expansion=normal:text=%@{localtime:%a %b %d %Y@}'
2319 For more information about libfreetype, check:
2320 @url{http://www.freetype.org/}.
2322 For more information about fontconfig, check:
2323 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
2327 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
2329 This filter accepts the following optional named parameters:
2333 Set low and high threshold values used by the Canny thresholding
2336 The high threshold selects the "strong" edge pixels, which are then
2337 connected through 8-connectivity with the "weak" edge pixels selected
2338 by the low threshold.
2340 @var{low} and @var{high} threshold values must be choosen in the range
2341 [0,1], and @var{low} should be lesser or equal to @var{high}.
2343 Default value for @var{low} is @code{20/255}, and default value for @var{high}
2349 edgedetect=low=0.1:high=0.4
2354 Apply fade-in/out effect to input video.
2356 The filter accepts parameters as a list of @var{key}=@var{value}
2357 pairs, separated by ":". If the key of the first options is omitted,
2358 the arguments are interpreted according to the syntax
2359 @var{type}:@var{start_frame}:@var{nb_frames}.
2361 A description of the accepted parameters follows.
2365 Specify if the effect type, can be either @code{in} for fade-in, or
2366 @code{out} for a fade-out effect. Default is @code{in}.
2368 @item start_frame, s
2369 Specify the number of the start frame for starting to apply the fade
2370 effect. Default is 0.
2373 Specify the number of frames for which the fade effect has to last. At
2374 the end of the fade-in effect the output video will have the same
2375 intensity as the input video, at the end of the fade-out transition
2376 the output video will be completely black. Default is 25.
2379 If set to 1, fade only alpha channel, if one exists on the input.
2383 @subsection Examples
2386 Fade in first 30 frames of video:
2391 The command above is equivalent to:
2397 Fade out last 45 frames of a 200-frame video:
2403 Fade in first 25 frames and fade out last 25 frames of a 1000-frame video:
2405 fade=in:0:25, fade=out:975:25
2409 Make first 5 frames black, then fade in from frame 5-24:
2415 Fade in alpha over first 25 frames of video:
2417 fade=in:0:25:alpha=1
2423 Extract a single field from an interlaced image using stride
2424 arithmetic to avoid wasting CPU time. The output frames are marked as
2427 This filter accepts the following named options:
2430 Specify whether to extract the top (if the value is @code{0} or
2431 @code{top}) or the bottom field (if the value is @code{1} or
2435 If the option key is not specified, the first value sets the @var{type}
2436 option. For example:
2448 Transform the field order of the input video.
2450 It accepts one parameter which specifies the required field order that
2451 the input interlaced video will be transformed to. The parameter can
2452 assume one of the following values:
2456 output bottom field first
2458 output top field first
2461 Default value is "tff".
2463 Transformation is achieved by shifting the picture content up or down
2464 by one line, and filling the remaining line with appropriate picture content.
2465 This method is consistent with most broadcast field order converters.
2467 If the input video is not flagged as being interlaced, or it is already
2468 flagged as being of the required output field order then this filter does
2469 not alter the incoming video.
2471 This filter is very useful when converting to or from PAL DV material,
2472 which is bottom field first.
2476 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
2481 Buffer input images and send them when they are requested.
2483 This filter is mainly useful when auto-inserted by the libavfilter
2486 The filter does not take parameters.
2490 Convert the input video to one of the specified pixel formats.
2491 Libavfilter will try to pick one that is supported for the input to
2494 The filter accepts a list of pixel format names, separated by ":",
2495 for example "yuv420p:monow:rgb24".
2497 Some examples follow:
2499 # convert the input video to the format "yuv420p"
2502 # convert the input video to any of the formats in the list
2503 format=yuv420p:yuv444p:yuv410p
2508 Convert the video to specified constant framerate by duplicating or dropping
2509 frames as necessary.
2511 This filter accepts the following named parameters:
2515 Desired output framerate. The default is @code{25}.
2520 Possible values are:
2523 zero round towards 0
2527 round towards -infinity
2529 round towards +infinity
2533 The default is @code{near}.
2537 Alternatively, the options can be specified as a flat string:
2538 @var{fps}[:@var{round}].
2540 See also the @ref{setpts} filter.
2544 Select one frame every N.
2546 This filter accepts in input a string representing a positive
2547 integer. Default argument is @code{1}.
2552 Apply a frei0r effect to the input video.
2554 To enable compilation of this filter you need to install the frei0r
2555 header and configure FFmpeg with @code{--enable-frei0r}.
2557 The filter supports the syntax:
2559 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
2562 @var{filter_name} is the name of the frei0r effect to load. If the
2563 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
2564 is searched in each one of the directories specified by the colon (or
2565 semicolon on Windows platforms) separated list in @env{FREIOR_PATH},
2566 otherwise in the standard frei0r paths, which are in this order:
2567 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
2568 @file{/usr/lib/frei0r-1/}.
2570 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
2571 for the frei0r effect.
2573 A frei0r effect parameter can be a boolean (whose values are specified
2574 with "y" and "n"), a double, a color (specified by the syntax
2575 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
2576 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
2577 description), a position (specified by the syntax @var{X}/@var{Y},
2578 @var{X} and @var{Y} being float numbers) and a string.
2580 The number and kind of parameters depend on the loaded effect. If an
2581 effect parameter is not specified the default value is set.
2583 Some examples follow:
2587 Apply the distort0r effect, set the first two double parameters:
2589 frei0r=distort0r:0.5:0.01
2593 Apply the colordistance effect, take a color as first parameter:
2595 frei0r=colordistance:0.2/0.3/0.4
2596 frei0r=colordistance:violet
2597 frei0r=colordistance:0x112233
2601 Apply the perspective effect, specify the top left and top right image
2604 frei0r=perspective:0.2/0.2:0.8/0.2
2608 For more information see:
2609 @url{http://frei0r.dyne.org}
2613 The filter takes one, two or three equations as parameter, separated by ':'.
2614 The first equation is mandatory and applies to the luma plane. The two
2615 following are respectively for chroma blue and chroma red planes.
2617 The filter syntax allows named parameters:
2621 the luminance expression
2623 the chrominance blue expression
2625 the chrominance red expression
2628 If one of the chrominance expression is not defined, it falls back on the other
2629 one. If none of them are specified, they will evaluate the luminance
2632 The expressions can use the following variables and functions:
2636 The sequential number of the filtered frame, starting from @code{0}.
2639 The coordinates of the current sample.
2642 The width and height of the image.
2645 Width and height scale depending on the currently filtered plane. It is the
2646 ratio between the corresponding luma plane number of pixels and the current
2647 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2648 @code{0.5,0.5} for chroma planes.
2651 Time of the current frame, expressed in seconds.
2654 Return the value of the pixel at location (@var{x},@var{y}) of the current
2658 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
2662 Return the value of the pixel at location (@var{x},@var{y}) of the
2663 blue-difference chroma plane.
2666 Return the value of the pixel at location (@var{x},@var{y}) of the
2667 red-difference chroma plane.
2670 For functions, if @var{x} and @var{y} are outside the area, the value will be
2671 automatically clipped to the closer edge.
2673 Some examples follow:
2677 Flip the image horizontally:
2683 Generate a bidimensional sine wave, with angle @code{PI/3} and a
2684 wavelength of 100 pixels:
2686 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
2690 Generate a fancy enigmatic moving light:
2692 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
2698 Fix the banding artifacts that are sometimes introduced into nearly flat
2699 regions by truncation to 8bit color depth.
2700 Interpolate the gradients that should go where the bands are, and
2703 This filter is designed for playback only. Do not use it prior to
2704 lossy compression, because compression tends to lose the dither and
2705 bring back the bands.
2707 The filter accepts a list of options in the form of @var{key}=@var{value} pairs
2708 separated by ":". A description of the accepted options follows.
2713 The maximum amount by which the filter will change
2714 any one pixel. Also the threshold for detecting nearly flat
2715 regions. Acceptable values range from @code{0.51} to @code{64}, default value
2719 The neighborhood to fit the gradient to. A larger
2720 radius makes for smoother gradients, but also prevents the filter from
2721 modifying the pixels near detailed regions. Acceptable values are
2722 @code{8-32}, default value is @code{16}.
2726 Alternatively, the options can be specified as a flat string:
2727 @var{strength}[:@var{radius}]
2729 @subsection Examples
2733 Apply the filter with a @code{3.5} strength and radius of @code{8}:
2739 Specify radius, omitting the strength (which will fall-back to the default
2749 Flip the input video horizontally.
2751 For example to horizontally flip the input video with @command{ffmpeg}:
2753 ffmpeg -i in.avi -vf "hflip" out.avi
2757 This filter applies a global color histogram equalization on a
2760 It can be used to correct video that has a compressed range of pixel
2761 intensities. The filter redistributes the pixel intensities to
2762 equalize their distribution across the intensity range. It may be
2763 viewed as an "automatically adjusting contrast filter". This filter is
2764 useful only for correcting degraded or poorly captured source
2767 The filter accepts parameters as a list of @var{key}=@var{value}
2768 pairs, separated by ":". If the key of the first options is omitted,
2769 the arguments are interpreted according to syntax
2770 @var{strength}:@var{intensity}:@var{antibanding}.
2772 This filter accepts the following named options:
2776 Determine the amount of equalization to be applied. As the strength
2777 is reduced, the distribution of pixel intensities more-and-more
2778 approaches that of the input frame. The value must be a float number
2779 in the range [0,1] and defaults to 0.200.
2782 Set the maximum intensity that can generated and scale the output
2783 values appropriately. The strength should be set as desired and then
2784 the intensity can be limited if needed to avoid washing-out. The value
2785 must be a float number in the range [0,1] and defaults to 0.210.
2788 Set the antibanding level. If enabled the filter will randomly vary
2789 the luminance of output pixels by a small amount to avoid banding of
2790 the histogram. Possible values are @code{none}, @code{weak} or
2791 @code{strong}. It defaults to @code{none}.
2796 High precision/quality 3d denoise filter. This filter aims to reduce
2797 image noise producing smooth images and making still images really
2798 still. It should enhance compressibility.
2800 It accepts the following optional parameters:
2801 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
2805 a non-negative float number which specifies spatial luma strength,
2808 @item chroma_spatial
2809 a non-negative float number which specifies spatial chroma strength,
2810 defaults to 3.0*@var{luma_spatial}/4.0
2813 a float number which specifies luma temporal strength, defaults to
2814 6.0*@var{luma_spatial}/4.0
2817 a float number which specifies chroma temporal strength, defaults to
2818 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
2823 Modify the hue and/or the saturation of the input.
2825 This filter accepts the following optional named options:
2829 Specify the hue angle as a number of degrees. It accepts a float
2830 number or an expression, and defaults to 0.0.
2833 Specify the hue angle as a number of degrees. It accepts a float
2834 number or an expression, and defaults to 0.0.
2837 Specify the saturation in the [-10,10] range. It accepts a float number and
2841 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
2842 following constants:
2846 frame count of the input frame starting from 0
2849 presentation timestamp of the input frame expressed in time base units
2852 frame rate of the input video, NAN if the input frame rate is unknown
2855 timestamp expressed in seconds, NAN if the input timestamp is unknown
2858 time base of the input video
2861 The options can also be set using the syntax: @var{hue}:@var{saturation}
2863 In this case @var{hue} is expressed in degrees.
2865 Some examples follow:
2868 Set the hue to 90 degrees and the saturation to 1.0:
2874 Same command but expressing the hue in radians:
2880 Same command without named options, hue must be expressed in degrees:
2886 Note that "h:s" syntax does not support expressions for the values of
2887 h and s, so the following example will issue an error:
2893 Rotate hue and make the saturation swing between 0
2894 and 2 over a period of 1 second:
2896 hue="H=2*PI*t: s=sin(2*PI*t)+1"
2900 Apply a 3 seconds saturation fade-in effect starting at 0:
2905 The general fade-in expression can be written as:
2907 hue="s=min(0\, max((t-START)/DURATION\, 1))"
2911 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
2913 hue="s=max(0\, min(1\, (8-t)/3))"
2916 The general fade-out expression can be written as:
2918 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
2923 @subsection Commands
2925 This filter supports the following command:
2928 Modify the hue and/or the saturation of the input video.
2929 The command accepts the same named options and syntax than when calling the
2930 filter from the command-line.
2932 If a parameter is omitted, it is kept at its current value.
2937 Interlaceing detect filter. This filter tries to detect if the input is
2938 interlaced or progressive. Top or bottom field first.
2942 Deinterlace input video by applying Donald Graft's adaptive kernel
2943 deinterling. Work on interlaced parts of a video to produce
2946 This filter accepts parameters as a list of @var{key}=@var{value}
2947 pairs, separated by ":". If the key of the first options is omitted,
2948 the arguments are interpreted according to the following syntax:
2949 @var{thresh}:@var{map}:@var{order}:@var{sharp}:@var{twoway}.
2951 The description of the accepted parameters follows.
2955 Set the threshold which affects the filter's tolerance when
2956 determining if a pixel line must be processed. It must be an integer
2957 in the range [0,255] and defaults to 10. A value of 0 will result in
2958 applying the process on every pixels.
2961 Paint pixels exceeding the threshold value to white if set to 1.
2965 Set the fields order. Swap fields if set to 1, leave fields alone if
2969 Enable additional sharpening if set to 1. Default is 0.
2972 Enable twoway sharpening if set to 1. Default is 0.
2975 @subsection Examples
2979 Apply default values:
2981 kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
2985 Enable additional sharpening:
2991 Paint processed pixels in white:
2997 @section lut, lutrgb, lutyuv
2999 Compute a look-up table for binding each pixel component input value
3000 to an output value, and apply it to input video.
3002 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
3003 to an RGB input video.
3005 These filters accept in input a ":"-separated list of options, which
3006 specify the expressions used for computing the lookup table for the
3007 corresponding pixel component values.
3009 The @var{lut} filter requires either YUV or RGB pixel formats in
3010 input, and accepts the options:
3012 @item @var{c0} (first pixel component)
3013 @item @var{c1} (second pixel component)
3014 @item @var{c2} (third pixel component)
3015 @item @var{c3} (fourth pixel component, corresponds to the alpha component)
3018 The exact component associated to each option depends on the format in
3021 The @var{lutrgb} filter requires RGB pixel formats in input, and
3022 accepts the options:
3024 @item @var{r} (red component)
3025 @item @var{g} (green component)
3026 @item @var{b} (blue component)
3027 @item @var{a} (alpha component)
3030 The @var{lutyuv} filter requires YUV pixel formats in input, and
3031 accepts the options:
3033 @item @var{y} (Y/luminance component)
3034 @item @var{u} (U/Cb component)
3035 @item @var{v} (V/Cr component)
3036 @item @var{a} (alpha component)
3039 The expressions can contain the following constants and functions:
3043 the input width and height
3046 input value for the pixel component
3049 the input value clipped in the @var{minval}-@var{maxval} range
3052 maximum value for the pixel component
3055 minimum value for the pixel component
3058 the negated value for the pixel component value clipped in the
3059 @var{minval}-@var{maxval} range , it corresponds to the expression
3060 "maxval-clipval+minval"
3063 the computed value in @var{val} clipped in the
3064 @var{minval}-@var{maxval} range
3066 @item gammaval(gamma)
3067 the computed gamma correction value of the pixel component value
3068 clipped in the @var{minval}-@var{maxval} range, corresponds to the
3070 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
3074 All expressions default to "val".
3076 Some examples follow:
3078 # negate input video
3079 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
3080 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
3082 # the above is the same as
3083 lutrgb="r=negval:g=negval:b=negval"
3084 lutyuv="y=negval:u=negval:v=negval"
3089 # remove chroma components, turns the video into a graytone image
3090 lutyuv="u=128:v=128"
3092 # apply a luma burning effect
3095 # remove green and blue components
3098 # set a constant alpha channel value on input
3099 format=rgba,lutrgb=a="maxval-minval/2"
3101 # correct luminance gamma by a 0.5 factor
3102 lutyuv=y=gammaval(0.5)
3107 Apply an MPlayer filter to the input video.
3109 This filter provides a wrapper around most of the filters of
3112 This wrapper is considered experimental. Some of the wrapped filters
3113 may not work properly and we may drop support for them, as they will
3114 be implemented natively into FFmpeg. Thus you should avoid
3115 depending on them when writing portable scripts.
3117 The filters accepts the parameters:
3118 @var{filter_name}[:=]@var{filter_params}
3120 @var{filter_name} is the name of a supported MPlayer filter,
3121 @var{filter_params} is a string containing the parameters accepted by
3124 The list of the currently supported filters follows:
3158 The parameter syntax and behavior for the listed filters are the same
3159 of the corresponding MPlayer filters. For detailed instructions check
3160 the "VIDEO FILTERS" section in the MPlayer manual.
3162 Some examples follow:
3165 Adjust gamma, brightness, contrast:
3171 Add temporal noise to input video:
3177 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
3183 This filter accepts an integer in input, if non-zero it negates the
3184 alpha component (if available). The default value in input is 0.
3188 Force libavfilter not to use any of the specified pixel formats for the
3189 input to the next filter.
3191 The filter accepts a list of pixel format names, separated by ":",
3192 for example "yuv420p:monow:rgb24".
3194 Some examples follow:
3196 # force libavfilter to use a format different from "yuv420p" for the
3197 # input to the vflip filter
3198 noformat=yuv420p,vflip
3200 # convert the input video to any of the formats not contained in the list
3201 noformat=yuv420p:yuv444p:yuv410p
3206 Pass the video source unchanged to the output.
3210 Apply video transform using libopencv.
3212 To enable this filter install libopencv library and headers and
3213 configure FFmpeg with @code{--enable-libopencv}.
3215 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
3217 @var{filter_name} is the name of the libopencv filter to apply.
3219 @var{filter_params} specifies the parameters to pass to the libopencv
3220 filter. If not specified the default values are assumed.
3222 Refer to the official libopencv documentation for more precise
3224 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
3226 Follows the list of supported libopencv filters.
3231 Dilate an image by using a specific structuring element.
3232 This filter corresponds to the libopencv function @code{cvDilate}.
3234 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
3236 @var{struct_el} represents a structuring element, and has the syntax:
3237 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
3239 @var{cols} and @var{rows} represent the number of columns and rows of
3240 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
3241 point, and @var{shape} the shape for the structuring element, and
3242 can be one of the values "rect", "cross", "ellipse", "custom".
3244 If the value for @var{shape} is "custom", it must be followed by a
3245 string of the form "=@var{filename}". The file with name
3246 @var{filename} is assumed to represent a binary image, with each
3247 printable character corresponding to a bright pixel. When a custom
3248 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
3249 or columns and rows of the read file are assumed instead.
3251 The default value for @var{struct_el} is "3x3+0x0/rect".
3253 @var{nb_iterations} specifies the number of times the transform is
3254 applied to the image, and defaults to 1.
3256 Follow some example:
3258 # use the default values
3261 # dilate using a structuring element with a 5x5 cross, iterate two times
3262 ocv=dilate=5x5+2x2/cross:2
3264 # read the shape from the file diamond.shape, iterate two times
3265 # the file diamond.shape may contain a pattern of characters like this:
3271 # the specified cols and rows are ignored (but not the anchor point coordinates)
3272 ocv=0x0+2x2/custom=diamond.shape:2
3277 Erode an image by using a specific structuring element.
3278 This filter corresponds to the libopencv function @code{cvErode}.
3280 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
3281 with the same syntax and semantics as the @ref{dilate} filter.
3285 Smooth the input video.
3287 The filter takes the following parameters:
3288 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
3290 @var{type} is the type of smooth filter to apply, and can be one of
3291 the following values: "blur", "blur_no_scale", "median", "gaussian",
3292 "bilateral". The default value is "gaussian".
3294 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
3295 parameters whose meanings depend on smooth type. @var{param1} and
3296 @var{param2} accept integer positive values or 0, @var{param3} and
3297 @var{param4} accept float values.
3299 The default value for @var{param1} is 3, the default value for the
3300 other parameters is 0.
3302 These parameters correspond to the parameters assigned to the
3303 libopencv function @code{cvSmooth}.
3308 Overlay one video on top of another.
3310 It takes two inputs and one output, the first input is the "main"
3311 video on which the second input is overlayed.
3313 This filter accepts a list of @var{key}=@var{value} pairs as argument,
3314 separated by ":". If the key of the first options is omitted, the
3315 arguments are interpreted according to the syntax @var{x}:@var{y}.
3317 A description of the accepted options follows.
3321 Set the expression for the x and y coordinates of the overlayed video
3322 on the main video. Default value is 0.
3324 The @var{x} and @var{y} expressions can contain the following
3327 @item main_w, main_h
3328 main input width and height
3331 same as @var{main_w} and @var{main_h}
3333 @item overlay_w, overlay_h
3334 overlay input width and height
3337 same as @var{overlay_w} and @var{overlay_h}
3341 If set to 1, force the filter to accept inputs in the RGB
3342 color space. Default value is 0.
3345 Be aware that frames are taken from each input video in timestamp
3346 order, hence, if their initial timestamps differ, it is a a good idea
3347 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
3348 have them begin in the same zero timestamp, as it does the example for
3349 the @var{movie} filter.
3351 You can chain together more overlays but you should test the
3352 efficiency of such approach.
3354 @subsection Examples
3358 Draw the overlay at 10 pixels from the bottom right corner of the main
3361 overlay=main_w-overlay_w-10:main_h-overlay_h-10
3364 Using named options the example above becomes:
3366 overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
3370 Insert a transparent PNG logo in the bottom left corner of the input,
3371 using the @command{ffmpeg} tool with the @code{-filter_complex} option:
3373 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
3377 Insert 2 different transparent PNG logos (second logo on bottom
3378 right corner) using the @command{ffmpeg} tool:
3380 ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
3384 Add a transparent color layer on top of the main video, WxH specifies
3385 the size of the main input to the overlay filter:
3387 color=red@@.3:WxH [over]; [in][over] overlay [out]
3391 Play an original video and a filtered version (here with the deshake
3392 filter) side by side using the @command{ffplay} tool:
3394 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
3397 The above command is the same as:
3399 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
3403 Chain several overlays in cascade:
3405 nullsrc=s=200x200 [bg];
3406 testsrc=s=100x100, split=4 [in0][in1][in2][in3];
3407 [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
3408 [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
3409 [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
3410 [in3] null, [mid2] overlay=100:100 [out0]
3417 Add paddings to the input image, and places the original input at the
3418 given coordinates @var{x}, @var{y}.
3420 It accepts the following parameters:
3421 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
3423 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
3424 expressions containing the following constants:
3428 the input video width and height
3431 same as @var{in_w} and @var{in_h}
3434 the output width and height, that is the size of the padded area as
3435 specified by the @var{width} and @var{height} expressions
3438 same as @var{out_w} and @var{out_h}
3441 x and y offsets as specified by the @var{x} and @var{y}
3442 expressions, or NAN if not yet specified
3445 same as @var{iw} / @var{ih}
3448 input sample aspect ratio
3451 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3454 horizontal and vertical chroma subsample values. For example for the
3455 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3458 Follows the description of the accepted parameters.
3463 Specify the size of the output image with the paddings added. If the
3464 value for @var{width} or @var{height} is 0, the corresponding input size
3465 is used for the output.
3467 The @var{width} expression can reference the value set by the
3468 @var{height} expression, and vice versa.
3470 The default value of @var{width} and @var{height} is 0.
3474 Specify the offsets where to place the input image in the padded area
3475 with respect to the top/left border of the output image.
3477 The @var{x} expression can reference the value set by the @var{y}
3478 expression, and vice versa.
3480 The default value of @var{x} and @var{y} is 0.
3484 Specify the color of the padded area, it can be the name of a color
3485 (case insensitive match) or a 0xRRGGBB[AA] sequence.
3487 The default value of @var{color} is "black".
3491 @subsection Examples
3495 Add paddings with color "violet" to the input video. Output video
3496 size is 640x480, the top-left corner of the input video is placed at
3499 pad=640:480:0:40:violet
3503 Pad the input to get an output with dimensions increased by 3/2,
3504 and put the input video at the center of the padded area:
3506 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
3510 Pad the input to get a squared output with size equal to the maximum
3511 value between the input width and height, and put the input video at
3512 the center of the padded area:
3514 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
3518 Pad the input to get a final w/h ratio of 16:9:
3520 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
3524 In case of anamorphic video, in order to set the output display aspect
3525 correctly, it is necessary to use @var{sar} in the expression,
3526 according to the relation:
3528 (ih * X / ih) * sar = output_dar
3529 X = output_dar / sar
3532 Thus the previous example needs to be modified to:
3534 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
3538 Double output size and put the input video in the bottom-right
3539 corner of the output padded area:
3541 pad="2*iw:2*ih:ow-iw:oh-ih"
3545 @section pixdesctest
3547 Pixel format descriptor test filter, mainly useful for internal
3548 testing. The output video should be equal to the input video.
3552 format=monow, pixdesctest
3555 can be used to test the monowhite pixel format descriptor definition.
3559 Enable the specified chain of postprocessing subfilters using libpostproc. This
3560 library should be automatically selected with a GPL build (@code{--enable-gpl}).
3561 Subfilters must be separated by '/' and can be disabled by prepending a '-'.
3562 Each subfilter and some options have a short and a long name that can be used
3563 interchangeably, i.e. dr/dering are the same.
3565 All subfilters share common options to determine their scope:
3569 Honor the quality commands for this subfilter.
3572 Do chrominance filtering, too (default).
3575 Do luminance filtering only (no chrominance).
3578 Do chrominance filtering only (no luminance).
3581 These options can be appended after the subfilter name, separated by a ':'.
3583 Available subfilters are:
3586 @item hb/hdeblock[:difference[:flatness]]
3587 Horizontal deblocking filter
3590 Difference factor where higher values mean more deblocking (default: @code{32}).
3592 Flatness threshold where lower values mean more deblocking (default: @code{39}).
3595 @item vb/vdeblock[:difference[:flatness]]
3596 Vertical deblocking filter
3599 Difference factor where higher values mean more deblocking (default: @code{32}).
3601 Flatness threshold where lower values mean more deblocking (default: @code{39}).
3604 @item ha/hadeblock[:difference[:flatness]]
3605 Accurate horizontal deblocking filter
3608 Difference factor where higher values mean more deblocking (default: @code{32}).
3610 Flatness threshold where lower values mean more deblocking (default: @code{39}).
3613 @item va/vadeblock[:difference[:flatness]]
3614 Accurate vertical deblocking filter
3617 Difference factor where higher values mean more deblocking (default: @code{32}).
3619 Flatness threshold where lower values mean more deblocking (default: @code{39}).
3623 The horizontal and vertical deblocking filters share the difference and
3624 flatness values so you cannot set different horizontal and vertical
3629 Experimental horizontal deblocking filter
3632 Experimental vertical deblocking filter
3637 @item tn/tmpnoise[:threshold1[:threshold2[:threshold3]]], temporal noise reducer
3640 larger -> stronger filtering
3642 larger -> stronger filtering
3644 larger -> stronger filtering
3647 @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction
3650 Stretch luminance to @code{0-255}.
3653 @item lb/linblenddeint
3654 Linear blend deinterlacing filter that deinterlaces the given block by
3655 filtering all lines with a @code{(1 2 1)} filter.
3657 @item li/linipoldeint
3658 Linear interpolating deinterlacing filter that deinterlaces the given block by
3659 linearly interpolating every second line.
3661 @item ci/cubicipoldeint
3662 Cubic interpolating deinterlacing filter deinterlaces the given block by
3663 cubically interpolating every second line.
3665 @item md/mediandeint
3666 Median deinterlacing filter that deinterlaces the given block by applying a
3667 median filter to every second line.
3669 @item fd/ffmpegdeint
3670 FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
3671 second line with a @code{(-1 4 2 4 -1)} filter.
3674 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given
3675 block by filtering all lines with a @code{(-1 2 6 2 -1)} filter.
3677 @item fq/forceQuant[:quantizer]
3678 Overrides the quantizer table from the input with the constant quantizer you
3686 Default pp filter combination (@code{hb:a,vb:a,dr:a})
3689 Fast pp filter combination (@code{h1:a,v1:a,dr:a})
3692 High quality pp filter combination (@code{ha:a:128:7,va:a,dr:a})
3695 @subsection Examples
3699 Apply horizontal and vertical deblocking, deringing and automatic
3700 brightness/contrast:
3706 Apply default filters without brightness/contrast correction:
3712 Apply default filters and temporal denoiser:
3714 pp=default/tmpnoise:1:2:3
3718 Apply deblocking on luminance only, and switch vertical deblocking on or off
3719 automatically depending on available CPU time:
3727 Suppress a TV station logo, using an image file to determine which
3728 pixels comprise the logo. It works by filling in the pixels that
3729 comprise the logo with neighboring pixels.
3731 This filter requires one argument which specifies the filter bitmap
3732 file, which can be any image format supported by libavformat. The
3733 width and height of the image file must match those of the video
3734 stream being processed.
3736 Pixels in the provided bitmap image with a value of zero are not
3737 considered part of the logo, non-zero pixels are considered part of
3738 the logo. If you use white (255) for the logo and black (0) for the
3739 rest, you will be safe. For making the filter bitmap, it is
3740 recommended to take a screen capture of a black frame with the logo
3741 visible, and then using a threshold filter followed by the erode
3742 filter once or twice.
3744 If needed, little splotches can be fixed manually. Remember that if
3745 logo pixels are not covered, the filter quality will be much
3746 reduced. Marking too many pixels as part of the logo does not hurt as
3747 much, but it will increase the amount of blurring needed to cover over
3748 the image and will destroy more information than necessary, and extra
3749 pixels will slow things down on a large logo.
3753 Scale (resize) the input video, using the libswscale library.
3755 The scale filter forces the output display aspect ratio to be the same
3756 of the input, by changing the output sample aspect ratio.
3758 This filter accepts a list of named options in the form of
3759 @var{key}=@var{value} pairs separated by ":". If the key for the first
3760 two options is not specified, the assumed keys for the first two
3761 values are @code{w} and @code{h}. If the first option has no key and
3762 can be interpreted like a video size specification, it will be used
3763 to set the video size.
3765 A description of the accepted options follows.
3769 Set the video width expression, default value is @code{iw}. See below
3770 for the list of accepted constants.
3773 Set the video heiht expression, default value is @code{ih}.
3774 See below for the list of accepted constants.
3777 Set the interlacing. It accepts the following values:
3781 force interlaced aware scaling
3784 do not apply interlaced scaling
3787 select interlaced aware scaling depending on whether the source frames
3788 are flagged as interlaced or not
3791 Default value is @code{0}.
3794 Set libswscale scaling flags. If not explictly specified the filter
3795 applies a bilinear scaling algorithm.
3798 Set the video size, the value must be a valid abbreviation or in the
3799 form @var{width}x@var{height}.
3802 The values of the @var{w} and @var{h} options are expressions
3803 containing the following constants:
3807 the input width and height
3810 same as @var{in_w} and @var{in_h}
3813 the output (cropped) width and height
3816 same as @var{out_w} and @var{out_h}
3819 same as @var{iw} / @var{ih}
3822 input sample aspect ratio
3825 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3828 horizontal and vertical chroma subsample values. For example for the
3829 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3832 If the input image format is different from the format requested by
3833 the next filter, the scale filter will convert the input to the
3836 If the value for @var{width} or @var{height} is 0, the respective input
3837 size is used for the output.
3839 If the value for @var{width} or @var{height} is -1, the scale filter will
3840 use, for the respective output size, a value that maintains the aspect
3841 ratio of the input image.
3843 @subsection Examples
3847 Scale the input video to a size of 200x100:
3852 This is equivalent to:
3863 Specify a size abbreviation for the output size:
3868 which can also be written as:
3874 Scale the input to 2x:
3880 The above is the same as:
3886 Scale the input to 2x with forced interlaced scaling:
3888 scale=2*iw:2*ih:interl=1
3892 Scale the input to half size:
3898 Increase the width, and set the height to the same size:
3904 Seek for Greek harmony:
3911 Increase the height, and set the width to 3/2 of the height:
3917 Increase the size, but make the size a multiple of the chroma:
3919 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
3923 Increase the width to a maximum of 500 pixels, keep the same input
3926 scale='min(500\, iw*3/2):-1'
3930 @section setdar, setsar
3932 The @code{setdar} filter sets the Display Aspect Ratio for the filter
3935 This is done by changing the specified Sample (aka Pixel) Aspect
3936 Ratio, according to the following equation:
3938 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
3941 Keep in mind that the @code{setdar} filter does not modify the pixel
3942 dimensions of the video frame. Also the display aspect ratio set by
3943 this filter may be changed by later filters in the filterchain,
3944 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
3947 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
3948 the filter output video.
3950 Note that as a consequence of the application of this filter, the
3951 output display aspect ratio will change according to the equation
3954 Keep in mind that the sample aspect ratio set by the @code{setsar}
3955 filter may be changed by later filters in the filterchain, e.g. if
3956 another "setsar" or a "setdar" filter is applied.
3958 The @code{setdar} and @code{setsar} filters accept a string in the
3959 form @var{num}:@var{den} expressing an aspect ratio, or the following
3960 named options, expressed as a sequence of @var{key}=@var{value} pairs,
3965 Set the maximum integer value to use for expressing numerator and
3966 denominator when reducing the expressed aspect ratio to a rational.
3967 Default value is @code{100}.
3970 Set the aspect ratio used by the filter.
3972 The parameter can be a floating point number string, an expression, or
3973 a string of the form @var{num}:@var{den}, where @var{num} and
3974 @var{den} are the numerator and denominator of the aspect ratio. If
3975 the parameter is not specified, it is assumed the value "0".
3976 In case the form "@var{num}:@var{den}" the @code{:} character should
3980 If the keys are omitted in the named options list, the specifed values
3981 are assumed to be @var{ratio} and @var{max} in that order.
3983 For example to change the display aspect ratio to 16:9, specify:
3988 The example above is equivalent to:
3993 To change the sample aspect ratio to 10:11, specify:
3998 To set a display aspect ratio of 16:9, and specify a maximum integer value of
3999 1000 in the aspect ratio reduction, use the command:
4001 setdar=ratio='16:9':max=1000
4006 Force field for the output video frame.
4008 The @code{setfield} filter marks the interlace type field for the
4009 output frames. It does not change the input frame, but only sets the
4010 corresponding property, which affects how the frame is treated by
4011 following filters (e.g. @code{fieldorder} or @code{yadif}).
4013 This filter accepts a single option @option{mode}, which can be
4014 specified either by setting @code{mode=VALUE} or setting the value
4015 alone. Available values are:
4019 Keep the same field property.
4022 Mark the frame as bottom-field-first.
4025 Mark the frame as top-field-first.
4028 Mark the frame as progressive.
4033 Show a line containing various information for each input video frame.
4034 The input video is not modified.
4036 The shown line contains a sequence of key/value pairs of the form
4037 @var{key}:@var{value}.
4039 A description of each shown parameter follows:
4043 sequential number of the input frame, starting from 0
4046 Presentation TimeStamp of the input frame, expressed as a number of
4047 time base units. The time base unit depends on the filter input pad.
4050 Presentation TimeStamp of the input frame, expressed as a number of
4054 position of the frame in the input stream, -1 if this information in
4055 unavailable and/or meaningless (for example in case of synthetic video)
4061 sample aspect ratio of the input frame, expressed in the form
4065 size of the input frame, expressed in the form
4066 @var{width}x@var{height}
4069 interlaced mode ("P" for "progressive", "T" for top field first, "B"
4070 for bottom field first)
4073 1 if the frame is a key frame, 0 otherwise
4076 picture type of the input frame ("I" for an I-frame, "P" for a
4077 P-frame, "B" for a B-frame, "?" for unknown type).
4078 Check also the documentation of the @code{AVPictureType} enum and of
4079 the @code{av_get_picture_type_char} function defined in
4080 @file{libavutil/avutil.h}.
4083 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
4085 @item plane_checksum
4086 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
4087 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
4092 Blur the input video without impacting the outlines.
4094 The filter accepts the following parameters:
4095 @var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
4097 Parameters prefixed by @var{luma} indicate that they work on the
4098 luminance of the pixels whereas parameters prefixed by @var{chroma}
4099 refer to the chrominance of the pixels.
4101 If the chroma parameters are not set, the luma parameters are used for
4102 either the luminance and the chrominance of the pixels.
4104 @var{luma_radius} or @var{chroma_radius} must be a float number in the
4105 range [0.1,5.0] that specifies the variance of the gaussian filter
4106 used to blur the image (slower if larger).
4108 @var{luma_strength} or @var{chroma_strength} must be a float number in
4109 the range [-1.0,1.0] that configures the blurring. A value included in
4110 [0.0,1.0] will blur the image whereas a value included in [-1.0,0.0]
4111 will sharpen the image.
4113 @var{luma_threshold} or @var{chroma_threshold} must be an integer in
4114 the range [-30,30] that is used as a coefficient to determine whether
4115 a pixel should be blurred or not. A value of 0 will filter all the
4116 image, a value included in [0,30] will filter flat areas and a value
4117 included in [-30,0] will filter edges.
4122 Draw subtitles on top of input video using the libass library.
4124 To enable compilation of this filter you need to configure FFmpeg with
4125 @code{--enable-libass}. This filter also requires a build with libavcodec and
4126 libavformat to convert the passed subtitles file to ASS (Advanced Substation
4127 Alpha) subtitles format.
4129 This filter accepts the following named options, expressed as a
4130 sequence of @var{key}=@var{value} pairs, separated by ":".
4134 Set the filename of the subtitle file to read. It must be specified.
4137 Specify the size of the original video, the video for which the ASS file
4138 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
4139 necessary to correctly scale the fonts if the aspect ratio has been changed.
4142 If the first key is not specified, it is assumed that the first value
4143 specifies the @option{filename}.
4145 For example, to render the file @file{sub.srt} on top of the input
4146 video, use the command:
4151 which is equivalent to:
4153 subtitles=filename=sub.srt
4158 Split input video into several identical outputs.
4160 The filter accepts a single parameter which specifies the number of outputs. If
4161 unspecified, it defaults to 2.
4165 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
4167 will create 5 copies of the input video.
4171 [in] split [splitout1][splitout2];
4172 [splitout1] crop=100:100:0:0 [cropout];
4173 [splitout2] pad=200:200:100:100 [padout];
4176 will create two separate outputs from the same input, one cropped and
4181 Scale the input by 2x and smooth using the Super2xSaI (Scale and
4182 Interpolate) pixel art scaling algorithm.
4184 Useful for enlarging pixel art images without reducing sharpness.
4190 Select the most representative frame in a given sequence of consecutive frames.
4192 It accepts as argument the frames batch size to analyze (default @var{N}=100);
4193 in a set of @var{N} frames, the filter will pick one of them, and then handle
4194 the next batch of @var{N} frames until the end.
4196 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
4197 value will result in a higher memory usage, so a high value is not recommended.
4199 The following example extract one picture each 50 frames:
4204 Complete example of a thumbnail creation with @command{ffmpeg}:
4206 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
4211 Tile several successive frames together.
4213 It accepts a list of options in the form of @var{key}=@var{value} pairs
4214 separated by ":". A description of the accepted options follows.
4219 Set the grid size (i.e. the number of lines and columns) in the form
4223 Set the outer border margin in pixels.
4226 Set the inner border thickness (i.e. the number of pixels between frames). For
4227 more advanced padding options (such as having different values for the edges),
4228 refer to the pad video filter.
4231 Set the maximum number of frames to render in the given area. It must be less
4232 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
4233 the area will be used.
4237 Alternatively, the options can be specified as a flat string:
4239 @var{layout}[:@var{nb_frames}[:@var{margin}[:@var{padding}]]]
4241 For example, produce 8×8 PNG tiles of all keyframes (@option{-skip_frame
4244 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
4246 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
4247 duplicating each output frame to accomodate the originally detected frame
4250 Another example to display @code{5} pictures in an area of @code{3x2} frames,
4251 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
4252 mixed flat and named options:
4254 tile=3x2:nb_frames=5:padding=7:margin=2
4259 Perform various types of temporal field interlacing.
4261 Frames are counted starting from 1, so the first input frame is
4264 This filter accepts options in the form of @var{key}=@var{value} pairs
4266 Alternatively, the @var{mode} option can be specified as a value alone,
4267 optionally followed by a ":" and further ":" separated @var{key}=@var{value}
4270 A description of the accepted options follows.
4275 Specify the mode of the interlacing. This option can also be specified
4276 as a value alone. See below for a list of values for this option.
4278 Available values are:
4282 Move odd frames into the upper field, even into the lower field,
4283 generating a double height frame at half framerate.
4286 Only output even frames, odd frames are dropped, generating a frame with
4287 unchanged height at half framerate.
4290 Only output odd frames, even frames are dropped, generating a frame with
4291 unchanged height at half framerate.
4294 Expand each frame to full height, but pad alternate lines with black,
4295 generating a frame with double height at the same input framerate.
4297 @item interleave_top, 4
4298 Interleave the upper field from odd frames with the lower field from
4299 even frames, generating a frame with unchanged height at half framerate.
4301 @item interleave_bottom, 5
4302 Interleave the lower field from odd frames with the upper field from
4303 even frames, generating a frame with unchanged height at half framerate.
4305 @item interlacex2, 6
4306 Double frame rate with unchanged height. Frames are inserted each
4307 containing the second temporal field from the previous input frame and
4308 the first temporal field from the next input frame. This mode relies on
4309 the top_field_first flag. Useful for interlaced video displays with no
4310 field synchronisation.
4313 Numeric values are deprecated but are accepted for backward
4314 compatibility reasons.
4316 Default mode is @code{merge}.
4319 Specify flags influencing the filter process.
4321 Available value for @var{flags} is:
4324 @item low_pass_filter, vlfp
4325 Enable vertical low-pass filtering in the filter.
4326 Vertical low-pass filtering is required when creating an interlaced
4327 destination from a progressive source which contains high-frequency
4328 vertical detail. Filtering will reduce interlace 'twitter' and Moire
4331 Vertical low-pass filtering can only be enabled for @option{mode}
4332 @var{interleave_top} and @var{interleave_bottom}.
4339 Transpose rows with columns in the input video and optionally flip it.
4341 The filter accepts parameters as a list of @var{key}=@var{value}
4342 pairs, separated by ':'. If the key of the first options is omitted,
4343 the arguments are interpreted according to the syntax
4344 @var{dir}:@var{passthrough}.
4348 Specify the transposition direction. Can assume the following values:
4352 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
4360 Rotate by 90 degrees clockwise, that is:
4368 Rotate by 90 degrees counterclockwise, that is:
4376 Rotate by 90 degrees clockwise and vertically flip, that is:
4384 For values between 4-7, the transposition is only done if the input
4385 video geometry is portrait and not landscape. These values are
4386 deprecated, the @code{passthrough} option should be used instead.
4389 Do not apply the transposition if the input geometry matches the one
4390 specified by the specified value. It accepts the following values:
4393 Always apply transposition.
4395 Preserve portrait geometry (when @var{height} >= @var{width}).
4397 Preserve landscape geometry (when @var{width} >= @var{height}).
4400 Default value is @code{none}.
4403 For example to rotate by 90 degrees clockwise and preserve portrait
4406 transpose=dir=1:passthrough=portrait
4409 The command above can also be specified as:
4411 transpose=1:portrait
4416 Sharpen or blur the input video.
4418 It accepts the following parameters:
4419 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
4421 Negative values for the amount will blur the input video, while positive
4422 values will sharpen. All parameters are optional and default to the
4423 equivalent of the string '5:5:1.0:5:5:0.0'.
4428 Set the luma matrix horizontal size. It can be an integer between 3
4429 and 13, default value is 5.
4432 Set the luma matrix vertical size. It can be an integer between 3
4433 and 13, default value is 5.
4436 Set the luma effect strength. It can be a float number between -2.0
4437 and 5.0, default value is 1.0.
4439 @item chroma_msize_x
4440 Set the chroma matrix horizontal size. It can be an integer between 3
4441 and 13, default value is 5.
4443 @item chroma_msize_y
4444 Set the chroma matrix vertical size. It can be an integer between 3
4445 and 13, default value is 5.
4448 Set the chroma effect strength. It can be a float number between -2.0
4449 and 5.0, default value is 0.0.
4454 # Strong luma sharpen effect parameters
4457 # Strong blur of both luma and chroma parameters
4458 unsharp=7:7:-2:7:7:-2
4460 # Use the default values with @command{ffmpeg}
4461 ffmpeg -i in.avi -vf "unsharp" out.mp4
4466 Flip the input video vertically.
4469 ffmpeg -i in.avi -vf "vflip" out.avi
4474 Deinterlace the input video ("yadif" means "yet another deinterlacing
4477 The filter accepts parameters as a list of @var{key}=@var{value}
4478 pairs, separated by ":". If the key of the first options is omitted,
4479 the arguments are interpreted according to syntax
4480 @var{mode}:@var{parity}:@var{deint}.
4482 The description of the accepted parameters follows.
4486 Specify the interlacing mode to adopt. Accept one of the following
4491 output 1 frame for each frame
4493 output 1 frame for each field
4494 @item 2, send_frame_nospatial
4495 like @code{send_frame} but skip spatial interlacing check
4496 @item 3, send_field_nospatial
4497 like @code{send_field} but skip spatial interlacing check
4500 Default value is @code{send_frame}.
4503 Specify the picture field parity assumed for the input interlaced
4504 video. Accept one of the following values:
4508 assume top field first
4510 assume bottom field first
4512 enable automatic detection
4515 Default value is @code{auto}.
4516 If interlacing is unknown or decoder does not export this information,
4517 top field first will be assumed.
4520 Specify which frames to deinterlace. Accept one of the following
4525 deinterlace all frames
4527 only deinterlace frames marked as interlaced
4530 Default value is @code{all}.
4533 @c man end VIDEO FILTERS
4535 @chapter Video Sources
4536 @c man begin VIDEO SOURCES
4538 Below is a description of the currently available video sources.
4542 Buffer video frames, and make them available to the filter chain.
4544 This source is mainly intended for a programmatic use, in particular
4545 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
4547 It accepts a list of options in the form of @var{key}=@var{value} pairs
4548 separated by ":". A description of the accepted options follows.
4553 Specify the size (width and height) of the buffered video frames.
4556 A string representing the pixel format of the buffered video frames.
4557 It may be a number corresponding to a pixel format, or a pixel format
4561 Specify the timebase assumed by the timestamps of the buffered frames.
4564 Specify the frame rate expected for the video stream.
4567 Specify the sample aspect ratio assumed by the video frames.
4570 Specify the optional parameters to be used for the scale filter which
4571 is automatically inserted when an input change is detected in the
4572 input size or format.
4577 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
4580 will instruct the source to accept video frames with size 320x240 and
4581 with format "yuv410p", assuming 1/24 as the timestamps timebase and
4582 square pixels (1:1 sample aspect ratio).
4583 Since the pixel format with name "yuv410p" corresponds to the number 6
4584 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
4585 this example corresponds to:
4587 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
4590 Alternatively, the options can be specified as a flat string, but this
4591 syntax is deprecated:
4593 @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}]
4597 Create a pattern generated by an elementary cellular automaton.
4599 The initial state of the cellular automaton can be defined through the
4600 @option{filename}, and @option{pattern} options. If such options are
4601 not specified an initial state is created randomly.
4603 At each new frame a new row in the video is filled with the result of
4604 the cellular automaton next generation. The behavior when the whole
4605 frame is filled is defined by the @option{scroll} option.
4607 This source accepts a list of options in the form of
4608 @var{key}=@var{value} pairs separated by ":". A description of the
4609 accepted options follows.
4613 Read the initial cellular automaton state, i.e. the starting row, from
4615 In the file, each non-whitespace character is considered an alive
4616 cell, a newline will terminate the row, and further characters in the
4617 file will be ignored.
4620 Read the initial cellular automaton state, i.e. the starting row, from
4621 the specified string.
4623 Each non-whitespace character in the string is considered an alive
4624 cell, a newline will terminate the row, and further characters in the
4625 string will be ignored.
4628 Set the video rate, that is the number of frames generated per second.
4631 @item random_fill_ratio, ratio
4632 Set the random fill ratio for the initial cellular automaton row. It
4633 is a floating point number value ranging from 0 to 1, defaults to
4636 This option is ignored when a file or a pattern is specified.
4638 @item random_seed, seed
4639 Set the seed for filling randomly the initial row, must be an integer
4640 included between 0 and UINT32_MAX. If not specified, or if explicitly
4641 set to -1, the filter will try to use a good random seed on a best
4645 Set the cellular automaton rule, it is a number ranging from 0 to 255.
4646 Default value is 110.
4649 Set the size of the output video.
4651 If @option{filename} or @option{pattern} is specified, the size is set
4652 by default to the width of the specified initial state row, and the
4653 height is set to @var{width} * PHI.
4655 If @option{size} is set, it must contain the width of the specified
4656 pattern string, and the specified pattern will be centered in the
4659 If a filename or a pattern string is not specified, the size value
4660 defaults to "320x518" (used for a randomly generated initial state).
4663 If set to 1, scroll the output upward when all the rows in the output
4664 have been already filled. If set to 0, the new generated row will be
4665 written over the top row just after the bottom row is filled.
4668 @item start_full, full
4669 If set to 1, completely fill the output with generated rows before
4670 outputting the first frame.
4671 This is the default behavior, for disabling set the value to 0.
4674 If set to 1, stitch the left and right row edges together.
4675 This is the default behavior, for disabling set the value to 0.
4678 @subsection Examples
4682 Read the initial state from @file{pattern}, and specify an output of
4685 cellauto=f=pattern:s=200x400
4689 Generate a random initial row with a width of 200 cells, with a fill
4692 cellauto=ratio=2/3:s=200x200
4696 Create a pattern generated by rule 18 starting by a single alive cell
4697 centered on an initial row with width 100:
4699 cellauto=p=@@:s=100x400:full=0:rule=18
4703 Specify a more elaborated initial pattern:
4705 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
4712 Generate a Mandelbrot set fractal, and progressively zoom towards the
4713 point specified with @var{start_x} and @var{start_y}.
4715 This source accepts a list of options in the form of
4716 @var{key}=@var{value} pairs separated by ":". A description of the
4717 accepted options follows.
4722 Set the terminal pts value. Default value is 400.
4725 Set the terminal scale value.
4726 Must be a floating point value. Default value is 0.3.
4729 Set the inner coloring mode, that is the algorithm used to draw the
4730 Mandelbrot fractal internal region.
4732 It shall assume one of the following values:
4737 Show time until convergence.
4739 Set color based on point closest to the origin of the iterations.
4744 Default value is @var{mincol}.
4747 Set the bailout value. Default value is 10.0.
4750 Set the maximum of iterations performed by the rendering
4751 algorithm. Default value is 7189.
4754 Set outer coloring mode.
4755 It shall assume one of following values:
4757 @item iteration_count
4758 Set iteration cound mode.
4759 @item normalized_iteration_count
4760 set normalized iteration count mode.
4762 Default value is @var{normalized_iteration_count}.
4765 Set frame rate, expressed as number of frames per second. Default
4769 Set frame size. Default value is "640x480".
4772 Set the initial scale value. Default value is 3.0.
4775 Set the initial x position. Must be a floating point value between
4776 -100 and 100. Default value is -0.743643887037158704752191506114774.
4779 Set the initial y position. Must be a floating point value between
4780 -100 and 100. Default value is -0.131825904205311970493132056385139.
4785 Generate various test patterns, as generated by the MPlayer test filter.
4787 The size of the generated video is fixed, and is 256x256.
4788 This source is useful in particular for testing encoding features.
4790 This source accepts an optional sequence of @var{key}=@var{value} pairs,
4791 separated by ":". The description of the accepted options follows.
4796 Specify the frame rate of the sourced video, as the number of frames
4797 generated per second. It has to be a string in the format
4798 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
4799 number or a valid video frame rate abbreviation. The default value is
4803 Set the video duration of the sourced video. The accepted syntax is:
4808 See also the function @code{av_parse_time()}.
4810 If not specified, or the expressed duration is negative, the video is
4811 supposed to be generated forever.
4815 Set the number or the name of the test to perform. Supported tests are:
4830 Default value is "all", which will cycle through the list of all tests.
4833 For example the following:
4838 will generate a "dc_luma" test pattern.
4842 Provide a frei0r source.
4844 To enable compilation of this filter you need to install the frei0r
4845 header and configure FFmpeg with @code{--enable-frei0r}.
4847 The source supports the syntax:
4849 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
4852 @var{size} is the size of the video to generate, may be a string of the
4853 form @var{width}x@var{height} or a frame size abbreviation.
4854 @var{rate} is the rate of the video to generate, may be a string of
4855 the form @var{num}/@var{den} or a frame rate abbreviation.
4856 @var{src_name} is the name to the frei0r source to load. For more
4857 information regarding frei0r and how to set the parameters read the
4858 section @ref{frei0r} in the description of the video filters.
4860 For example, to generate a frei0r partik0l source with size 200x200
4861 and frame rate 10 which is overlayed on the overlay filter main input:
4863 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
4868 Generate a life pattern.
4870 This source is based on a generalization of John Conway's life game.
4872 The sourced input represents a life grid, each pixel represents a cell
4873 which can be in one of two possible states, alive or dead. Every cell
4874 interacts with its eight neighbours, which are the cells that are
4875 horizontally, vertically, or diagonally adjacent.
4877 At each interaction the grid evolves according to the adopted rule,
4878 which specifies the number of neighbor alive cells which will make a
4879 cell stay alive or born. The @option{rule} option allows to specify
4882 This source accepts a list of options in the form of
4883 @var{key}=@var{value} pairs separated by ":". A description of the
4884 accepted options follows.
4888 Set the file from which to read the initial grid state. In the file,
4889 each non-whitespace character is considered an alive cell, and newline
4890 is used to delimit the end of each row.
4892 If this option is not specified, the initial grid is generated
4896 Set the video rate, that is the number of frames generated per second.
4899 @item random_fill_ratio, ratio
4900 Set the random fill ratio for the initial random grid. It is a
4901 floating point number value ranging from 0 to 1, defaults to 1/PHI.
4902 It is ignored when a file is specified.
4904 @item random_seed, seed
4905 Set the seed for filling the initial random grid, must be an integer
4906 included between 0 and UINT32_MAX. If not specified, or if explicitly
4907 set to -1, the filter will try to use a good random seed on a best
4913 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
4914 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
4915 @var{NS} specifies the number of alive neighbor cells which make a
4916 live cell stay alive, and @var{NB} the number of alive neighbor cells
4917 which make a dead cell to become alive (i.e. to "born").
4918 "s" and "b" can be used in place of "S" and "B", respectively.
4920 Alternatively a rule can be specified by an 18-bits integer. The 9
4921 high order bits are used to encode the next cell state if it is alive
4922 for each number of neighbor alive cells, the low order bits specify
4923 the rule for "borning" new cells. Higher order bits encode for an
4924 higher number of neighbor cells.
4925 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
4926 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
4928 Default value is "S23/B3", which is the original Conway's game of life
4929 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
4930 cells, and will born a new cell if there are three alive cells around
4934 Set the size of the output video.
4936 If @option{filename} is specified, the size is set by default to the
4937 same size of the input file. If @option{size} is set, it must contain
4938 the size specified in the input file, and the initial grid defined in
4939 that file is centered in the larger resulting area.
4941 If a filename is not specified, the size value defaults to "320x240"
4942 (used for a randomly generated initial grid).
4945 If set to 1, stitch the left and right grid edges together, and the
4946 top and bottom edges also. Defaults to 1.
4949 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
4950 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
4951 value from 0 to 255.
4954 Set the color of living (or new born) cells.
4957 Set the color of dead cells. If @option{mold} is set, this is the first color
4958 used to represent a dead cell.
4961 Set mold color, for definitely dead and moldy cells.
4964 @subsection Examples
4968 Read a grid from @file{pattern}, and center it on a grid of size
4971 life=f=pattern:s=300x300
4975 Generate a random grid of size 200x200, with a fill ratio of 2/3:
4977 life=ratio=2/3:s=200x200
4981 Specify a custom rule for evolving a randomly generated grid:
4987 Full example with slow death effect (mold) using @command{ffplay}:
4989 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
4993 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
4995 The @code{color} source provides an uniformly colored input.
4997 The @code{nullsrc} source returns unprocessed video frames. It is
4998 mainly useful to be employed in analysis / debugging tools, or as the
4999 source for filters which ignore the input data.
5001 The @code{rgbtestsrc} source generates an RGB test pattern useful for
5002 detecting RGB vs BGR issues. You should see a red, green and blue
5003 stripe from top to bottom.
5005 The @code{smptebars} source generates a color bars pattern, based on
5006 the SMPTE Engineering Guideline EG 1-1990.
5008 The @code{testsrc} source generates a test video pattern, showing a
5009 color pattern, a scrolling gradient and a timestamp. This is mainly
5010 intended for testing purposes.
5012 These sources accept an optional sequence of @var{key}=@var{value} pairs,
5013 separated by ":". The description of the accepted options follows.
5018 Specify the color of the source, only used in the @code{color}
5019 source. It can be the name of a color (case insensitive match) or a
5020 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
5021 default value is "black".
5024 Specify the size of the sourced video, it may be a string of the form
5025 @var{width}x@var{height}, or the name of a size abbreviation. The
5026 default value is "320x240".
5029 Specify the frame rate of the sourced video, as the number of frames
5030 generated per second. It has to be a string in the format
5031 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
5032 number or a valid video frame rate abbreviation. The default value is
5036 Set the sample aspect ratio of the sourced video.
5039 Set the video duration of the sourced video. The accepted syntax is:
5041 [-]HH[:MM[:SS[.m...]]]
5044 See also the function @code{av_parse_time()}.
5046 If not specified, or the expressed duration is negative, the video is
5047 supposed to be generated forever.
5050 Set the number of decimals to show in the timestamp, only used in the
5051 @code{testsrc} source.
5053 The displayed timestamp value will correspond to the original
5054 timestamp value multiplied by the power of 10 of the specified
5055 value. Default value is 0.
5058 For example the following:
5060 testsrc=duration=5.3:size=qcif:rate=10
5063 will generate a video with a duration of 5.3 seconds, with size
5064 176x144 and a frame rate of 10 frames per second.
5066 The following graph description will generate a red source
5067 with an opacity of 0.2, with size "qcif" and a frame rate of 10
5070 color=c=red@@0.2:s=qcif:r=10
5073 If the input content is to be ignored, @code{nullsrc} can be used. The
5074 following command generates noise in the luminance plane by employing
5075 the @code{geq} filter:
5077 nullsrc=s=256x256, geq=random(1)*255:128:128
5080 @c man end VIDEO SOURCES
5082 @chapter Video Sinks
5083 @c man begin VIDEO SINKS
5085 Below is a description of the currently available video sinks.
5089 Buffer video frames, and make them available to the end of the filter
5092 This sink is mainly intended for a programmatic use, in particular
5093 through the interface defined in @file{libavfilter/buffersink.h}.
5095 It does not require a string parameter in input, but you need to
5096 specify a pointer to a list of supported pixel formats terminated by
5097 -1 in the opaque parameter provided to @code{avfilter_init_filter}
5098 when initializing this sink.
5102 Null video sink, do absolutely nothing with the input video. It is
5103 mainly useful as a template and to be employed in analysis / debugging
5106 @c man end VIDEO SINKS
5108 @chapter Multimedia Filters
5109 @c man begin MULTIMEDIA FILTERS
5111 Below is a description of the currently available multimedia filters.
5113 @section aselect, select
5114 Select frames to pass in output.
5116 These filters accept a single option @option{expr} or @option{e}
5117 specifying the select expression, which can be specified either by
5118 specyfing @code{expr=VALUE} or specifying the expression
5121 The select expression is evaluated for each input frame. If the
5122 evaluation result is a non-zero value, the frame is selected and
5123 passed to the output, otherwise it is discarded.
5125 The expression can contain the following constants:
5129 the sequential number of the filtered frame, starting from 0
5132 the sequential number of the selected frame, starting from 0
5134 @item prev_selected_n
5135 the sequential number of the last selected frame, NAN if undefined
5138 timebase of the input timestamps
5141 the PTS (Presentation TimeStamp) of the filtered video frame,
5142 expressed in @var{TB} units, NAN if undefined
5145 the PTS (Presentation TimeStamp) of the filtered video frame,
5146 expressed in seconds, NAN if undefined
5149 the PTS of the previously filtered video frame, NAN if undefined
5151 @item prev_selected_pts
5152 the PTS of the last previously filtered video frame, NAN if undefined
5154 @item prev_selected_t
5155 the PTS of the last previously selected video frame, NAN if undefined
5158 the PTS of the first video frame in the video, NAN if undefined
5161 the time of the first video frame in the video, NAN if undefined
5163 @item pict_type @emph{(video only)}
5164 the type of the filtered frame, can assume one of the following
5176 @item interlace_type @emph{(video only)}
5177 the frame interlace type, can assume one of the following values:
5180 the frame is progressive (not interlaced)
5182 the frame is top-field-first
5184 the frame is bottom-field-first
5187 @item consumed_sample_n @emph{(audio only)}
5188 the number of selected samples before the current frame
5190 @item samples_n @emph{(audio only)}
5191 the number of samples in the current frame
5193 @item sample_rate @emph{(audio only)}
5194 the input sample rate
5197 1 if the filtered frame is a key-frame, 0 otherwise
5200 the position in the file of the filtered frame, -1 if the information
5201 is not available (e.g. for synthetic video)
5203 @item scene @emph{(video only)}
5204 value between 0 and 1 to indicate a new scene; a low value reflects a low
5205 probability for the current frame to introduce a new scene, while a higher
5206 value means the current frame is more likely to be one (see the example below)
5210 The default value of the select expression is "1".
5212 @subsection Examples
5216 Select all frames in input:
5221 The example above is the same as:
5233 Select only I-frames:
5235 select='eq(pict_type\,I)'
5239 Select one frame every 100:
5241 select='not(mod(n\,100))'
5245 Select only frames contained in the 10-20 time interval:
5247 select='gte(t\,10)*lte(t\,20)'
5251 Select only I frames contained in the 10-20 time interval:
5253 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
5257 Select frames with a minimum distance of 10 seconds:
5259 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
5263 Use aselect to select only audio frames with samples number > 100:
5265 aselect='gt(samples_n\,100)'
5269 Create a mosaic of the first scenes:
5271 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
5274 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
5278 @section asendcmd, sendcmd
5280 Send commands to filters in the filtergraph.
5282 These filters read commands to be sent to other filters in the
5285 @code{asendcmd} must be inserted between two audio filters,
5286 @code{sendcmd} must be inserted between two video filters, but apart
5287 from that they act the same way.
5289 The specification of commands can be provided in the filter arguments
5290 with the @var{commands} option, or in a file specified by the
5291 @var{filename} option.
5293 These filters accept the following options:
5296 Set the commands to be read and sent to the other filters.
5298 Set the filename of the commands to be read and sent to the other
5302 @subsection Commands syntax
5304 A commands description consists of a sequence of interval
5305 specifications, comprising a list of commands to be executed when a
5306 particular event related to that interval occurs. The occurring event
5307 is typically the current frame time entering or leaving a given time
5310 An interval is specified by the following syntax:
5312 @var{START}[-@var{END}] @var{COMMANDS};
5315 The time interval is specified by the @var{START} and @var{END} times.
5316 @var{END} is optional and defaults to the maximum time.
5318 The current frame time is considered within the specified interval if
5319 it is included in the interval [@var{START}, @var{END}), that is when
5320 the time is greater or equal to @var{START} and is lesser than
5323 @var{COMMANDS} consists of a sequence of one or more command
5324 specifications, separated by ",", relating to that interval. The
5325 syntax of a command specification is given by:
5327 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
5330 @var{FLAGS} is optional and specifies the type of events relating to
5331 the time interval which enable sending the specified command, and must
5332 be a non-null sequence of identifier flags separated by "+" or "|" and
5333 enclosed between "[" and "]".
5335 The following flags are recognized:
5338 The command is sent when the current frame timestamp enters the
5339 specified interval. In other words, the command is sent when the
5340 previous frame timestamp was not in the given interval, and the
5344 The command is sent when the current frame timestamp leaves the
5345 specified interval. In other words, the command is sent when the
5346 previous frame timestamp was in the given interval, and the
5350 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
5353 @var{TARGET} specifies the target of the command, usually the name of
5354 the filter class or a specific filter instance name.
5356 @var{COMMAND} specifies the name of the command for the target filter.
5358 @var{ARG} is optional and specifies the optional list of argument for
5359 the given @var{COMMAND}.
5361 Between one interval specification and another, whitespaces, or
5362 sequences of characters starting with @code{#} until the end of line,
5363 are ignored and can be used to annotate comments.
5365 A simplified BNF description of the commands specification syntax
5368 @var{COMMAND_FLAG} ::= "enter" | "leave"
5369 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
5370 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
5371 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
5372 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
5373 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
5376 @subsection Examples
5380 Specify audio tempo change at second 4:
5382 asendcmd=c='4.0 atempo tempo 1.5',atempo
5386 Specify a list of drawtext and hue commands in a file.
5388 # show text in the interval 5-10
5389 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
5390 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
5392 # desaturate the image in the interval 15-20
5393 15.0-20.0 [enter] hue reinit s=0,
5394 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
5395 [leave] hue reinit s=1,
5396 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
5398 # apply an exponential saturation fade-out effect, starting from time 25
5399 25 [enter] hue s=exp(t-25)
5402 A filtergraph allowing to read and process the above command list
5403 stored in a file @file{test.cmd}, can be specified with:
5405 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
5410 @section asetpts, setpts
5412 Change the PTS (presentation timestamp) of the input frames.
5414 @code{asetpts} works on audio frames, @code{setpts} on video frames.
5416 Accept in input an expression evaluated through the eval API, which
5417 can contain the following constants:
5421 frame rate, only defined for constant frame-rate video
5424 the presentation timestamp in input
5427 the count of the input frame, starting from 0.
5429 @item NB_CONSUMED_SAMPLES
5430 the number of consumed samples, not including the current frame (only
5434 the number of samples in the current frame (only audio)
5440 the PTS of the first frame
5443 the time in seconds of the first frame
5446 tell if the current frame is interlaced
5449 the time in seconds of the current frame
5455 original position in the file of the frame, or undefined if undefined
5456 for the current frame
5462 previous input time in seconds
5468 previous output time in seconds
5471 @subsection Examples
5475 Start counting PTS from zero
5481 Apply fast motion effect:
5487 Apply slow motion effect:
5493 Set fixed rate of 25 frames per second:
5499 Set fixed rate 25 fps with some jitter:
5501 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
5505 Apply an offset of 10 seconds to the input PTS:
5513 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
5514 it unchanged. By default, it logs a message at a frequency of 10Hz with the
5515 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
5516 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
5518 The filter also has a video output (see the @var{video} option) with a real
5519 time graph to observe the loudness evolution. The graphic contains the logged
5520 message mentioned above, so it is not printed anymore when this option is set,
5521 unless the verbose logging is set. The main graphing area contains the
5522 short-term loudness (3 seconds of analysis), and the gauge on the right is for
5523 the momentary loudness (400 milliseconds).
5525 More information about the Loudness Recommendation EBU R128 on
5526 @url{http://tech.ebu.ch/loudness}.
5528 The filter accepts the following named parameters:
5533 Activate the video output. The audio stream is passed unchanged whether this
5534 option is set or no. The video stream will be the first output stream if
5535 activated. Default is @code{0}.
5538 Set the video size. This option is for video only. Default and minimum
5539 resolution is @code{640x480}.
5542 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
5543 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
5544 other integer value between this range is allowed.
5548 Example of real-time graph using @command{ffplay}, with a EBU scale meter +18:
5550 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
5553 Run an analysis with @command{ffmpeg}:
5555 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
5558 @section settb, asettb
5560 Set the timebase to use for the output frames timestamps.
5561 It is mainly useful for testing timebase configuration.
5563 It accepts in input an arithmetic expression representing a rational.
5564 The expression can contain the constants "AVTB" (the
5565 default timebase), "intb" (the input timebase) and "sr" (the sample rate,
5568 The default value for the input is "intb".
5570 @subsection Examples
5574 Set the timebase to 1/25:
5580 Set the timebase to 1/10:
5586 Set the timebase to 1001/1000:
5592 Set the timebase to 2*intb:
5598 Set the default timebase value:
5606 Concatenate audio and video streams, joining them together one after the
5609 The filter works on segments of synchronized video and audio streams. All
5610 segments must have the same number of streams of each type, and that will
5611 also be the number of streams at output.
5613 The filter accepts the following named parameters:
5617 Set the number of segments. Default is 2.
5620 Set the number of output video streams, that is also the number of video
5621 streams in each segment. Default is 1.
5624 Set the number of output audio streams, that is also the number of video
5625 streams in each segment. Default is 0.
5628 Activate unsafe mode: do not fail if segments have a different format.
5632 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
5633 @var{a} audio outputs.
5635 There are @var{n}×(@var{v}+@var{a}) inputs: first the inputs for the first
5636 segment, in the same order as the outputs, then the inputs for the second
5639 Related streams do not always have exactly the same duration, for various
5640 reasons including codec frame size or sloppy authoring. For that reason,
5641 related synchronized streams (e.g. a video and its audio track) should be
5642 concatenated at once. The concat filter will use the duration of the longest
5643 stream in each segment (except the last one), and if necessary pad shorter
5644 audio streams with silence.
5646 For this filter to work correctly, all segments must start at timestamp 0.
5648 All corresponding streams must have the same parameters in all segments; the
5649 filtering system will automatically select a common pixel format for video
5650 streams, and a common sample format, sample rate and channel layout for
5651 audio streams, but other settings, such as resolution, must be converted
5652 explicitly by the user.
5654 Different frame rates are acceptable but will result in variable frame rate
5655 at output; be sure to configure the output file to handle it.
5660 Concatenate an opening, an episode and an ending, all in bilingual version
5661 (video in stream 0, audio in streams 1 and 2):
5663 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
5664 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
5665 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
5666 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
5670 Concatenate two parts, handling audio and video separately, using the
5671 (a)movie sources, and adjusting the resolution:
5673 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
5674 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
5675 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
5677 Note that a desync will happen at the stitch if the audio and video streams
5678 do not have exactly the same duration in the first file.
5682 @section showspectrum
5684 Convert input audio to a video output, representing the audio frequency
5687 The filter accepts the following named parameters:
5690 Specify the video size for the output. Default value is @code{640x480}.
5692 Specify if the spectrum should slide along the window. Default value is
5696 The usage is very similar to the showwaves filter; see the examples in that
5701 Convert input audio to a video output, representing the samples waves.
5703 The filter accepts the following named parameters:
5707 Set the number of samples which are printed on the same column. A
5708 larger value will decrease the frame rate. Must be a positive
5709 integer. This option can be set only if the value for @var{rate}
5710 is not explicitly specified.
5713 Set the (approximate) output frame rate. This is done by setting the
5714 option @var{n}. Default value is "25".
5717 Specify the video size for the output. Default value is "600x240".
5720 Some examples follow.
5723 Output the input file audio and the corresponding video representation
5726 amovie=a.mp3,asplit[out0],showwaves[out1]
5730 Create a synthetic signal and show it with showwaves, forcing a
5731 framerate of 30 frames per second:
5733 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
5737 @c man end MULTIMEDIA FILTERS
5739 @chapter Multimedia Sources
5740 @c man begin MULTIMEDIA SOURCES
5742 Below is a description of the currently available multimedia sources.
5746 This is the same as @ref{movie} source, except it selects an audio
5752 Read audio and/or video stream(s) from a movie container.
5754 It accepts the syntax: @var{movie_name}[:@var{options}] where
5755 @var{movie_name} is the name of the resource to read (not necessarily
5756 a file but also a device or a stream accessed through some protocol),
5757 and @var{options} is an optional sequence of @var{key}=@var{value}
5758 pairs, separated by ":".
5760 The description of the accepted options follows.
5764 @item format_name, f
5765 Specifies the format assumed for the movie to read, and can be either
5766 the name of a container or an input device. If not specified the
5767 format is guessed from @var{movie_name} or by probing.
5769 @item seek_point, sp
5770 Specifies the seek point in seconds, the frames will be output
5771 starting from this seek point, the parameter is evaluated with
5772 @code{av_strtod} so the numerical value may be suffixed by an IS
5773 postfix. Default value is "0".
5776 Specifies the streams to read. Several streams can be specified,
5777 separated by "+". The source will then have as many outputs, in the
5778 same order. The syntax is explained in the ``Stream specifiers''
5779 section in the ffmpeg manual. Two special names, "dv" and "da" specify
5780 respectively the default (best suited) video and audio stream. Default
5781 is "dv", or "da" if the filter is called as "amovie".
5783 @item stream_index, si
5784 Specifies the index of the video stream to read. If the value is -1,
5785 the best suited video stream will be automatically selected. Default
5786 value is "-1". Deprecated. If the filter is called "amovie", it will select
5787 audio instead of video.
5790 Specifies how many times to read the stream in sequence.
5791 If the value is less than 1, the stream will be read again and again.
5792 Default value is "1".
5794 Note that when the movie is looped the source timestamps are not
5795 changed, so it will generate non monotonically increasing timestamps.
5798 This filter allows to overlay a second video on top of main input of
5799 a filtergraph as shown in this graph:
5801 input -----------> deltapts0 --> overlay --> output
5804 movie --> scale--> deltapts1 -------+
5807 Some examples follow.
5811 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
5812 on top of the input labelled as "in":
5814 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
5815 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
5819 Read from a video4linux2 device, and overlay it on top of the input
5822 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
5823 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
5827 Read the first video stream and the audio stream with id 0x81 from
5828 dvd.vob; the video is connected to the pad named "video" and the audio is
5829 connected to the pad named "audio":
5831 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
5835 @c man end MULTIMEDIA SOURCES