1 @chapter Filtering Introduction
2 @c man begin FILTERING INTRODUCTION
4 Filtering in FFmpeg is enabled through the libavfilter library.
6 Libavfilter is the filtering API of FFmpeg. It is the substitute of
7 the now deprecated 'vhooks' and started as a Google Summer of Code
10 Audio filtering integration into the main FFmpeg repository is a work in
11 progress, so audio API and ABI should not be considered stable yet.
13 In libavfilter, it is possible for filters to have multiple inputs and
15 To illustrate the sorts of things that are possible, we can
16 use a complex filter graph. For example, the following one:
19 input --> split --> fifo -----------------------> overlay --> output
22 +------> fifo --> crop --> vflip --------+
25 splits the stream in two streams, sends one stream through the crop filter
26 and the vflip filter before merging it back with the other stream by
27 overlaying it on top. You can use the following command to achieve this:
30 ffmpeg -i input -vf "[in] split [T1], fifo, [T2] overlay=0:H/2 [out]; [T1] fifo, crop=iw:ih/2:0:ih/2, vflip [T2]" output
33 The result will be that in output the top half of the video is mirrored
36 Filters are loaded using the @var{-vf} or @var{-af} option passed to
37 @command{ffmpeg} or to @command{ffplay}. Filters in the same linear
38 chain are separated by commas. In our example, @var{split, fifo,
39 overlay} are in one linear chain, and @var{fifo, crop, vflip} are in
40 another. The points where the linear chains join are labeled by names
41 enclosed in square brackets. In our example, that is @var{[T1]} and
42 @var{[T2]}. The special labels @var{[in]} and @var{[out]} are the points
43 where video is input and output.
45 Some filters take in input a list of parameters: they are specified
46 after the filter name and an equal sign, and are separated from each other
49 There exist so-called @var{source filters} that do not have an
50 audio/video input, and @var{sink filters} that will not have audio/video
53 @c man end FILTERING INTRODUCTION
56 @c man begin GRAPH2DOT
58 The @file{graph2dot} program included in the FFmpeg @file{tools}
59 directory can be used to parse a filter graph description and issue a
60 corresponding textual representation in the dot language.
67 to see how to use @file{graph2dot}.
69 You can then pass the dot description to the @file{dot} program (from
70 the graphviz suite of programs) and obtain a graphical representation
73 For example the sequence of commands:
75 echo @var{GRAPH_DESCRIPTION} | \
76 tools/graph2dot -o graph.tmp && \
77 dot -Tpng graph.tmp -o graph.png && \
81 can be used to create and display an image representing the graph
82 described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
83 a complete self-contained graph, with its inputs and outputs explicitly defined.
84 For example if your command line is of the form:
86 ffmpeg -i infile -vf scale=640:360 outfile
88 your @var{GRAPH_DESCRIPTION} string will need to be of the form:
90 nullsrc,scale=640:360,nullsink
92 you may also need to set the @var{nullsrc} parameters and add a @var{format}
93 filter in order to simulate a specific input file.
97 @chapter Filtergraph description
98 @c man begin FILTERGRAPH DESCRIPTION
100 A filtergraph is a directed graph of connected filters. It can contain
101 cycles, and there can be multiple links between a pair of
102 filters. Each link has one input pad on one side connecting it to one
103 filter from which it takes its input, and one output pad on the other
104 side connecting it to the one filter accepting its output.
106 Each filter in a filtergraph is an instance of a filter class
107 registered in the application, which defines the features and the
108 number of input and output pads of the filter.
110 A filter with no input pads is called a "source", a filter with no
111 output pads is called a "sink".
113 @anchor{Filtergraph syntax}
114 @section Filtergraph syntax
116 A filtergraph can be represented using a textual representation, which is
117 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
118 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
119 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
120 @file{libavfilter/avfiltergraph.h}.
122 A filterchain consists of a sequence of connected filters, each one
123 connected to the previous one in the sequence. A filterchain is
124 represented by a list of ","-separated filter descriptions.
126 A filtergraph consists of a sequence of filterchains. A sequence of
127 filterchains is represented by a list of ";"-separated filterchain
130 A filter is represented by a string of the form:
131 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
133 @var{filter_name} is the name of the filter class of which the
134 described filter is an instance of, and has to be the name of one of
135 the filter classes registered in the program.
136 The name of the filter class is optionally followed by a string
139 @var{arguments} is a string which contains the parameters used to
140 initialize the filter instance, and are described in the filter
143 The list of arguments can be quoted using the character "'" as initial
144 and ending mark, and the character '\' for escaping the characters
145 within the quoted text; otherwise the argument string is considered
146 terminated when the next special character (belonging to the set
147 "[]=;,") is encountered.
149 The name and arguments of the filter are optionally preceded and
150 followed by a list of link labels.
151 A link label allows to name a link and associate it to a filter output
152 or input pad. The preceding labels @var{in_link_1}
153 ... @var{in_link_N}, are associated to the filter input pads,
154 the following labels @var{out_link_1} ... @var{out_link_M}, are
155 associated to the output pads.
157 When two link labels with the same name are found in the
158 filtergraph, a link between the corresponding input and output pad is
161 If an output pad is not labelled, it is linked by default to the first
162 unlabelled input pad of the next filter in the filterchain.
163 For example in the filterchain:
165 nullsrc, split[L1], [L2]overlay, nullsink
167 the split filter instance has two output pads, and the overlay filter
168 instance two input pads. The first output pad of split is labelled
169 "L1", the first input pad of overlay is labelled "L2", and the second
170 output pad of split is linked to the second input pad of overlay,
171 which are both unlabelled.
173 In a complete filterchain all the unlabelled filter input and output
174 pads must be connected. A filtergraph is considered valid if all the
175 filter input and output pads of all the filterchains are connected.
177 Libavfilter will automatically insert scale filters where format
178 conversion is required. It is possible to specify swscale flags
179 for those automatically inserted scalers by prepending
180 @code{sws_flags=@var{flags};}
181 to the filtergraph description.
183 Follows a BNF description for the filtergraph syntax:
185 @var{NAME} ::= sequence of alphanumeric characters and '_'
186 @var{LINKLABEL} ::= "[" @var{NAME} "]"
187 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
188 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
189 @var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
190 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
191 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
194 @section Notes on filtergraph escaping
196 Some filter arguments require the use of special characters, typically
197 @code{:} to separate key=value pairs in a named options list. In this
198 case the user should perform a first level escaping when specifying
199 the filter arguments. For example, consider the following literal
200 string to be embedded in the @ref{drawtext} filter arguments:
202 this is a 'string': may contain one, or more, special characters
205 Since @code{:} is special for the filter arguments syntax, it needs to
206 be escaped, so you get:
208 text=this is a \'string\'\: may contain one, or more, special characters
211 A second level of escaping is required when embedding the filter
212 arguments in a filtergraph description, in order to escape all the
213 filtergraph special characters. Thus the example above becomes:
215 drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
218 Finally an additional level of escaping may be needed when writing the
219 filtergraph description in a shell command, which depends on the
220 escaping rules of the adopted shell. For example, assuming that
221 @code{\} is special and needs to be escaped with another @code{\}, the
222 previous string will finally result in:
224 -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
227 Sometimes, it might be more convenient to employ quoting in place of
228 escaping. For example the string:
230 Caesar: tu quoque, Brute, fili mi
233 Can be quoted in the filter arguments as:
235 text='Caesar: tu quoque, Brute, fili mi'
238 And finally inserted in a filtergraph like:
240 drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
243 See the @ref{quoting_and_escaping, Quoting and escaping} section for
244 more information about the escaping and quoting rules adopted by
247 @c man end FILTERGRAPH DESCRIPTION
249 @chapter Audio Filters
250 @c man begin AUDIO FILTERS
252 When you configure your FFmpeg build, you can disable any of the
253 existing filters using @code{--disable-filters}.
254 The configure output will show the audio filters included in your
257 Below is a description of the currently available audio filters.
261 Convert the input audio format to the specified formats.
263 The filter accepts a string of the form:
264 "@var{sample_format}:@var{channel_layout}".
266 @var{sample_format} specifies the sample format, and can be a string or the
267 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
268 suffix for a planar sample format.
270 @var{channel_layout} specifies the channel layout, and can be a string
271 or the corresponding number value defined in @file{libavutil/channel_layout.h}.
273 The special parameter "auto", signifies that the filter will
274 automatically select the output format depending on the output filter.
276 Some examples follow.
280 Convert input to float, planar, stereo:
286 Convert input to unsigned 8-bit, automatically select out channel layout:
294 Convert the input audio to one of the specified formats. The framework will
295 negotiate the most appropriate format to minimize conversions.
297 The filter accepts the following named parameters:
301 A comma-separated list of requested sample formats.
304 A comma-separated list of requested sample rates.
306 @item channel_layouts
307 A comma-separated list of requested channel layouts.
311 If a parameter is omitted, all values are allowed.
313 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
315 aformat=sample_fmts\=u8\,s16:channel_layouts\=stereo
320 Merge two or more audio streams into a single multi-channel stream.
322 The filter accepts the following named options:
327 Set the number of inputs. Default is 2.
331 If the channel layouts of the inputs are disjoint, and therefore compatible,
332 the channel layout of the output will be set accordingly and the channels
333 will be reordered as necessary. If the channel layouts of the inputs are not
334 disjoint, the output will have all the channels of the first input then all
335 the channels of the second input, in that order, and the channel layout of
336 the output will be the default value corresponding to the total number of
339 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
340 is FC+BL+BR, then the output will be in 5.1, with the channels in the
341 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
342 first input, b1 is the first channel of the second input).
344 On the other hand, if both input are in stereo, the output channels will be
345 in the default order: a1, a2, b1, b2, and the channel layout will be
346 arbitrarily set to 4.0, which may or may not be the expected value.
348 All inputs must have the same sample rate, and format.
350 If inputs do not have the same duration, the output will stop with the
353 Example: merge two mono files into a stereo stream:
355 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
358 Example: multiple merges:
361 amovie=input.mkv:si=0 [a0];
362 amovie=input.mkv:si=1 [a1];
363 amovie=input.mkv:si=2 [a2];
364 amovie=input.mkv:si=3 [a3];
365 amovie=input.mkv:si=4 [a4];
366 amovie=input.mkv:si=5 [a5];
367 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
372 Mixes multiple audio inputs into a single output.
376 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
378 will mix 3 input audio streams to a single output with the same duration as the
379 first input and a dropout transition time of 3 seconds.
381 The filter accepts the following named parameters:
385 Number of inputs. If unspecified, it defaults to 2.
388 How to determine the end-of-stream.
392 Duration of longest input. (default)
395 Duration of shortest input.
398 Duration of first input.
402 @item dropout_transition
403 Transition time, in seconds, for volume renormalization when an input
404 stream ends. The default value is 2 seconds.
410 Pass the audio source unchanged to the output.
414 Resample the input audio to the specified sample rate.
416 The filter accepts exactly one parameter, the output sample rate. If not
417 specified then the filter will automatically convert between its input
418 and output sample rates.
420 For example, to resample the input audio to 44100Hz:
425 @section asetnsamples
427 Set the number of samples per each output audio frame.
429 The last output packet may contain a different number of samples, as
430 the filter will flush all the remaining samples when the input audio
433 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
438 @item nb_out_samples, n
439 Set the number of frames per each output audio frame. The number is
440 intended as the number of samples @emph{per each channel}.
441 Default value is 1024.
444 If set to 1, the filter will pad the last audio frame with zeroes, so
445 that the last frame will contain the same number of samples as the
446 previous ones. Default value is 1.
449 For example, to set the number of per-frame samples to 1234 and
450 disable padding for the last frame, use:
452 asetnsamples=n=1234:p=0
457 Show a line containing various information for each input audio frame.
458 The input audio is not modified.
460 The shown line contains a sequence of key/value pairs of the form
461 @var{key}:@var{value}.
463 A description of each shown parameter follows:
467 sequential number of the input frame, starting from 0
470 Presentation timestamp of the input frame, in time base units; the time base
471 depends on the filter input pad, and is usually 1/@var{sample_rate}.
474 presentation timestamp of the input frame in seconds
477 position of the frame in the input stream, -1 if this information in
478 unavailable and/or meaningless (for example in case of synthetic audio)
487 sample rate for the audio frame
490 number of samples (per channel) in the frame
493 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
494 the data is treated as if all the planes were concatenated.
496 @item plane_checksums
497 A list of Adler-32 checksums for each data plane.
502 Split input audio into several identical outputs.
504 The filter accepts a single parameter which specifies the number of outputs. If
505 unspecified, it defaults to 2.
509 [in] asplit [out0][out1]
512 will create two separate outputs from the same input.
514 To create 3 or more outputs, you need to specify the number of
517 [in] asplit=3 [out0][out1][out2]
521 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
523 will create 5 copies of the input audio.
528 Forward two audio streams and control the order the buffers are forwarded.
530 The argument to the filter is an expression deciding which stream should be
531 forwarded next: if the result is negative, the first stream is forwarded; if
532 the result is positive or zero, the second stream is forwarded. It can use
533 the following variables:
537 number of buffers forwarded so far on each stream
539 number of samples forwarded so far on each stream
541 current timestamp of each stream
544 The default value is @code{t1-t2}, which means to always forward the stream
545 that has a smaller timestamp.
547 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
548 input, while avoiding too much of a desynchronization:
550 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
551 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
559 The filter accepts exactly one parameter, the audio tempo. If not
560 specified then the filter will assume nominal 1.0 tempo. Tempo must
561 be in the [0.5, 2.0] range.
563 For example, to slow down audio to 80% tempo:
568 For example, to speed up audio to 125% tempo:
575 Make audio easier to listen to on headphones.
577 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
578 so that when listened to on headphones the stereo image is moved from
579 inside your head (standard for headphones) to outside and in front of
580 the listener (standard for speakers).
586 Mix channels with specific gain levels. The filter accepts the output
587 channel layout followed by a set of channels definitions.
589 This filter is also designed to remap efficiently the channels of an audio
592 The filter accepts parameters of the form:
593 "@var{l}:@var{outdef}:@var{outdef}:..."
597 output channel layout or number of channels
600 output channel specification, of the form:
601 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
604 output channel to define, either a channel name (FL, FR, etc.) or a channel
605 number (c0, c1, etc.)
608 multiplicative coefficient for the channel, 1 leaving the volume unchanged
611 input channel to use, see out_name for details; it is not possible to mix
612 named and numbered input channels
615 If the `=' in a channel specification is replaced by `<', then the gains for
616 that specification will be renormalized so that the total is 1, thus
617 avoiding clipping noise.
619 @subsection Mixing examples
621 For example, if you want to down-mix from stereo to mono, but with a bigger
622 factor for the left channel:
624 pan=1:c0=0.9*c0+0.1*c1
627 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
630 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
633 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
634 that should be preferred (see "-ac" option) unless you have very specific
637 @subsection Remapping examples
639 The channel remapping will be effective if, and only if:
642 @item gain coefficients are zeroes or ones,
643 @item only one input per channel output,
646 If all these conditions are satisfied, the filter will notify the user ("Pure
647 channel mapping detected"), and use an optimized and lossless method to do the
650 For example, if you have a 5.1 source and want a stereo audio stream by
651 dropping the extra channels:
653 pan="stereo: c0=FL : c1=FR"
656 Given the same source, you can also switch front left and front right channels
657 and keep the input channel layout:
659 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
662 If the input is a stereo audio stream, you can mute the front left channel (and
663 still keep the stereo channel layout) with:
668 Still with a stereo audio stream input, you can copy the right channel in both
669 front left and right:
671 pan="stereo: c0=FR : c1=FR"
674 @section silencedetect
676 Detect silence in an audio stream.
678 This filter logs a message when it detects that the input audio volume is less
679 or equal to a noise tolerance value for a duration greater or equal to the
680 minimum detected noise duration.
682 The printed times and duration are expressed in seconds.
686 Set silence duration until notification (default is 2 seconds).
689 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
690 specified value) or amplitude ratio. Default is -60dB, or 0.001.
693 Detect 5 seconds of silence with -50dB noise tolerance:
695 silencedetect=n=-50dB:d=5
698 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
699 tolerance in @file{silence.mp3}:
701 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
705 Synchronize audio data with timestamps by squeezing/stretching it and/or
706 dropping samples/adding silence when needed.
708 The filter accepts the following named parameters:
712 Enable stretching/squeezing the data to make it match the timestamps. Disabled
713 by default. When disabled, time gaps are covered with silence.
716 Minimum difference between timestamps and audio data (in seconds) to trigger
717 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
718 this filter, try setting this parameter to 0.
721 Maximum compensation in samples per second. Relevant only with compensate=1.
725 Assume the first pts should be this value.
726 This allows for padding/trimming at the start of stream. By default, no
727 assumption is made about the first frame's expected pts, so no padding or
728 trimming is done. For example, this could be set to 0 to pad the beginning with
729 silence if an audio stream starts after the video stream.
733 @section channelsplit
734 Split each channel in input audio stream into a separate output stream.
736 This filter accepts the following named parameters:
739 Channel layout of the input stream. Default is "stereo".
742 For example, assuming a stereo input MP3 file
744 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
746 will create an output Matroska file with two audio streams, one containing only
747 the left channel and the other the right channel.
749 To split a 5.1 WAV file into per-channel files
751 ffmpeg -i in.wav -filter_complex
752 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
753 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
754 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
759 Remap input channels to new locations.
761 This filter accepts the following named parameters:
764 Channel layout of the output stream.
767 Map channels from input to output. The argument is a comma-separated list of
768 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
769 @var{in_channel} form. @var{in_channel} can be either the name of the input
770 channel (e.g. FL for front left) or its index in the input channel layout.
771 @var{out_channel} is the name of the output channel or its index in the output
772 channel layout. If @var{out_channel} is not given then it is implicitly an
773 index, starting with zero and increasing by one for each mapping.
776 If no mapping is present, the filter will implicitly map input channels to
777 output channels preserving index.
779 For example, assuming a 5.1+downmix input MOV file
781 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
783 will create an output WAV file tagged as stereo from the downmix channels of
786 To fix a 5.1 WAV improperly encoded in AAC's native channel order
788 ffmpeg -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
792 Join multiple input streams into one multi-channel stream.
794 The filter accepts the following named parameters:
798 Number of input streams. Defaults to 2.
801 Desired output channel layout. Defaults to stereo.
804 Map channels from inputs to output. The argument is a comma-separated list of
805 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
806 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
807 can be either the name of the input channel (e.g. FL for front left) or its
808 index in the specified input stream. @var{out_channel} is the name of the output
812 The filter will attempt to guess the mappings when those are not specified
813 explicitly. It does so by first trying to find an unused matching input channel
814 and if that fails it picks the first unused input channel.
816 E.g. to join 3 inputs (with properly set channel layouts)
818 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
821 To build a 5.1 output from 6 single-channel streams:
823 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
824 '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'
829 Convert the audio sample format, sample rate and channel layout. This filter is
830 not meant to be used directly.
834 Adjust the input audio volume.
836 The filter accepts exactly one parameter @var{vol}, which expresses
837 how the audio volume will be increased or decreased.
839 Output values are clipped to the maximum value.
841 If @var{vol} is expressed as a decimal number, the output audio
842 volume is given by the relation:
844 @var{output_volume} = @var{vol} * @var{input_volume}
847 If @var{vol} is expressed as a decimal number followed by the string
848 "dB", the value represents the requested change in decibels of the
849 input audio power, and the output audio volume is given by the
852 @var{output_volume} = 10^(@var{vol}/20) * @var{input_volume}
855 Otherwise @var{vol} is considered an expression and its evaluated
856 value is used for computing the output audio volume according to the
859 Default value for @var{vol} is 1.0.
865 Half the input audio volume:
870 The above example is equivalent to:
876 Decrease input audio power by 12 decibels:
882 @section volumedetect
884 Detect the volume of the input video.
886 The filter has no parameters. The input is not modified. Statistics about
887 the volume will be printed in the log when the input stream end is reached.
889 In particular it will show the mean volume (root mean square), maximum
890 volume (on a per-sample basis), and the beginning of an histogram of the
891 registered volume values (from the maximum value to a cumulated 1/1000 of
894 All volumes are in decibels relative to the maximum PCM value.
896 Here is an excerpt of the output:
898 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
899 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
900 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
901 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
902 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
903 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
904 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
905 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
906 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
912 The mean square energy is approximately -27 dB, or 10^-2.7.
914 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
916 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
919 In other words, raising the volume by +4 dB does not cause any clipping,
920 raising it by +5 dB causes clipping for 6 samples, etc.
922 @section volume_justin
924 Adjust the input audio volume.
926 The filter accepts the following named parameters:
930 Expresses how the audio volume will be increased or decreased.
932 Output values are clipped to the maximum value.
934 The output audio volume is given by the relation:
936 @var{output_volume} = @var{volume} * @var{input_volume}
939 Default value for @var{volume} is 1.0.
942 Mathematical precision.
944 This determines which input sample formats will be allowed, which affects the
945 precision of the volume scaling.
949 8-bit fixed-point; limits input sample format to U8, S16, and S32.
951 32-bit floating-point; limits input sample format to FLT. (default)
953 64-bit floating-point; limits input sample format to DBL.
961 Halve the input audio volume:
963 volume_justin=volume=0.5
964 volume_justin=volume=1/2
965 volume_justin=volume=-6.0206dB
969 Increase input audio power by 6 decibels using fixed-point precision:
971 volume_justin=volume=6dB:precision=fixed
975 @c man end AUDIO FILTERS
977 @chapter Audio Sources
978 @c man begin AUDIO SOURCES
980 Below is a description of the currently available audio sources.
984 Buffer audio frames, and make them available to the filter chain.
986 This source is mainly intended for a programmatic use, in particular
987 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
989 It accepts the following mandatory parameters:
990 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
995 The sample rate of the incoming audio buffers.
998 The sample format of the incoming audio buffers.
999 Either a sample format name or its corresponging integer representation from
1000 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1002 @item channel_layout
1003 The channel layout of the incoming audio buffers.
1004 Either a channel layout name from channel_layout_map in
1005 @file{libavutil/channel_layout.c} or its corresponding integer representation
1006 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1012 abuffer=44100:s16p:stereo
1015 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1016 Since the sample format with name "s16p" corresponds to the number
1017 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1025 Generate an audio signal specified by an expression.
1027 This source accepts in input one or more expressions (one for each
1028 channel), which are evaluated and used to generate a corresponding
1031 It accepts the syntax: @var{exprs}[::@var{options}].
1032 @var{exprs} is a list of expressions separated by ":", one for each
1033 separate channel. In case the @var{channel_layout} is not
1034 specified, the selected channel layout depends on the number of
1035 provided expressions.
1037 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1040 The description of the accepted options follows.
1044 @item channel_layout, c
1045 Set the channel layout. The number of channels in the specified layout
1046 must be equal to the number of specified expressions.
1049 Set the minimum duration of the sourced audio. See the function
1050 @code{av_parse_time()} for the accepted format.
1051 Note that the resulting duration may be greater than the specified
1052 duration, as the generated audio is always cut at the end of a
1055 If not specified, or the expressed duration is negative, the audio is
1056 supposed to be generated forever.
1059 Set the number of samples per channel per each output frame,
1062 @item sample_rate, s
1063 Specify the sample rate, default to 44100.
1066 Each expression in @var{exprs} can contain the following constants:
1070 number of the evaluated sample, starting from 0
1073 time of the evaluated sample expressed in seconds, starting from 0
1080 @subsection Examples
1092 Generate a sin signal with frequency of 440 Hz, set sample rate to
1095 aevalsrc="sin(440*2*PI*t)::s=8000"
1099 Generate a two channels signal, specify the channel layout (Front
1100 Center + Back Center) explicitly:
1102 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1106 Generate white noise:
1108 aevalsrc="-2+random(0)"
1112 Generate an amplitude modulated signal:
1114 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1118 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1120 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1127 Null audio source, return unprocessed audio frames. It is mainly useful
1128 as a template and to be employed in analysis / debugging tools, or as
1129 the source for filters which ignore the input data (for example the sox
1132 It accepts an optional sequence of @var{key}=@var{value} pairs,
1135 The description of the accepted options follows.
1139 @item sample_rate, s
1140 Specify the sample rate, and defaults to 44100.
1142 @item channel_layout, cl
1144 Specify the channel layout, and can be either an integer or a string
1145 representing a channel layout. The default value of @var{channel_layout}
1148 Check the channel_layout_map definition in
1149 @file{libavutil/channel_layout.c} for the mapping between strings and
1150 channel layout values.
1153 Set the number of samples per requested frames.
1157 Follow some examples:
1159 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1160 anullsrc=r=48000:cl=4
1163 anullsrc=r=48000:cl=mono
1167 Buffer audio frames, and make them available to the filter chain.
1169 This source is not intended to be part of user-supplied graph descriptions but
1170 for insertion by calling programs through the interface defined in
1171 @file{libavfilter/buffersrc.h}.
1173 It accepts the following named parameters:
1177 Timebase which will be used for timestamps of submitted frames. It must be
1178 either a floating-point number or in @var{numerator}/@var{denominator} form.
1184 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1186 @item channel_layout
1187 Channel layout of the audio data, in the form that can be accepted by
1188 @code{av_get_channel_layout()}.
1191 All the parameters need to be explicitly defined.
1195 Synthesize a voice utterance using the libflite library.
1197 To enable compilation of this filter you need to configure FFmpeg with
1198 @code{--enable-libflite}.
1200 Note that the flite library is not thread-safe.
1202 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1205 The description of the accepted parameters follows.
1210 If set to 1, list the names of the available voices and exit
1211 immediately. Default value is 0.
1214 Set the maximum number of samples per frame. Default value is 512.
1217 Set the filename containing the text to speak.
1220 Set the text to speak.
1223 Set the voice to use for the speech synthesis. Default value is
1224 @code{kal}. See also the @var{list_voices} option.
1227 @subsection Examples
1231 Read from file @file{speech.txt}, and synthetize the text using the
1232 standard flite voice:
1234 flite=textfile=speech.txt
1238 Read the specified text selecting the @code{slt} voice:
1240 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1244 Input text to ffmpeg:
1246 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1250 Make @file{ffplay} speak the specified text, using @code{flite} and
1251 the @code{lavfi} device:
1253 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1257 For more information about libflite, check:
1258 @url{http://www.speech.cs.cmu.edu/flite/}
1260 @c man end AUDIO SOURCES
1262 @chapter Audio Sinks
1263 @c man begin AUDIO SINKS
1265 Below is a description of the currently available audio sinks.
1267 @section abuffersink
1269 Buffer audio frames, and make them available to the end of filter chain.
1271 This sink is mainly intended for programmatic use, in particular
1272 through the interface defined in @file{libavfilter/buffersink.h}.
1274 It requires a pointer to an AVABufferSinkContext structure, which
1275 defines the incoming buffers' formats, to be passed as the opaque
1276 parameter to @code{avfilter_init_filter} for initialization.
1280 Null audio sink, do absolutely nothing with the input audio. It is
1281 mainly useful as a template and to be employed in analysis / debugging
1284 @section abuffersink
1285 This sink is intended for programmatic use. Frames that arrive on this sink can
1286 be retrieved by the calling program using the interface defined in
1287 @file{libavfilter/buffersink.h}.
1289 This filter accepts no parameters.
1291 @c man end AUDIO SINKS
1293 @chapter Video Filters
1294 @c man begin VIDEO FILTERS
1296 When you configure your FFmpeg build, you can disable any of the
1297 existing filters using @code{--disable-filters}.
1298 The configure output will show the video filters included in your
1301 Below is a description of the currently available video filters.
1303 @section alphaextract
1305 Extract the alpha component from the input as a grayscale video. This
1306 is especially useful with the @var{alphamerge} filter.
1310 Add or replace the alpha component of the primary input with the
1311 grayscale value of a second input. This is intended for use with
1312 @var{alphaextract} to allow the transmission or storage of frame
1313 sequences that have alpha in a format that doesn't support an alpha
1316 For example, to reconstruct full frames from a normal YUV-encoded video
1317 and a separate video created with @var{alphaextract}, you might use:
1319 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1322 Since this filter is designed for reconstruction, it operates on frame
1323 sequences without considering timestamps, and terminates when either
1324 input reaches end of stream. This will cause problems if your encoding
1325 pipeline drops frames. If you're trying to apply an image as an
1326 overlay to a video stream, consider the @var{overlay} filter instead.
1330 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1331 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1332 Substation Alpha) subtitles files.
1336 Compute the bounding box for the non-black pixels in the input frame
1339 This filter computes the bounding box containing all the pixels with a
1340 luminance value greater than the minimum allowed value.
1341 The parameters describing the bounding box are printed on the filter
1344 @section blackdetect
1346 Detect video intervals that are (almost) completely black. Can be
1347 useful to detect chapter transitions, commercials, or invalid
1348 recordings. Output lines contains the time for the start, end and
1349 duration of the detected black interval expressed in seconds.
1351 In order to display the output lines, you need to set the loglevel at
1352 least to the AV_LOG_INFO value.
1354 This filter accepts a list of options in the form of
1355 @var{key}=@var{value} pairs separated by ":". A description of the
1356 accepted options follows.
1359 @item black_min_duration, d
1360 Set the minimum detected black duration expressed in seconds. It must
1361 be a non-negative floating point number.
1363 Default value is 2.0.
1365 @item picture_black_ratio_th, pic_th
1366 Set the threshold for considering a picture "black".
1367 Express the minimum value for the ratio:
1369 @var{nb_black_pixels} / @var{nb_pixels}
1372 for which a picture is considered black.
1373 Default value is 0.98.
1375 @item pixel_black_th, pix_th
1376 Set the threshold for considering a pixel "black".
1378 The threshold expresses the maximum pixel luminance value for which a
1379 pixel is considered "black". The provided value is scaled according to
1380 the following equation:
1382 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1385 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1386 the input video format, the range is [0-255] for YUV full-range
1387 formats and [16-235] for YUV non full-range formats.
1389 Default value is 0.10.
1392 The following example sets the maximum pixel threshold to the minimum
1393 value, and detects only black intervals of 2 or more seconds:
1395 blackdetect=d=2:pix_th=0.00
1400 Detect frames that are (almost) completely black. Can be useful to
1401 detect chapter transitions or commercials. Output lines consist of
1402 the frame number of the detected frame, the percentage of blackness,
1403 the position in the file if known or -1 and the timestamp in seconds.
1405 In order to display the output lines, you need to set the loglevel at
1406 least to the AV_LOG_INFO value.
1408 The filter accepts the syntax:
1410 blackframe[=@var{amount}:[@var{threshold}]]
1413 @var{amount} is the percentage of the pixels that have to be below the
1414 threshold, and defaults to 98.
1416 @var{threshold} is the threshold below which a pixel value is
1417 considered black, and defaults to 32.
1421 Apply boxblur algorithm to the input video.
1423 This filter accepts the parameters:
1424 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
1426 Chroma and alpha parameters are optional, if not specified they default
1427 to the corresponding values set for @var{luma_radius} and
1430 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
1431 the radius in pixels of the box used for blurring the corresponding
1432 input plane. They are expressions, and can contain the following
1436 the input width and height in pixels
1439 the input chroma image width and height in pixels
1442 horizontal and vertical chroma subsample values. For example for the
1443 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1446 The radius must be a non-negative number, and must not be greater than
1447 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
1448 and of @code{min(cw,ch)/2} for the chroma planes.
1450 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
1451 how many times the boxblur filter is applied to the corresponding
1454 Some examples follow:
1459 Apply a boxblur filter with luma, chroma, and alpha radius
1466 Set luma radius to 2, alpha and chroma radius to 0
1472 Set luma and chroma radius to a fraction of the video dimension
1474 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
1479 @section colormatrix
1481 The colormatrix filter allows conversion between any of the following color
1482 space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m})
1483 and FCC (@var{fcc}).
1485 The syntax of the parameters is @var{source}:@var{destination}:
1488 colormatrix=bt601:smpte240m
1493 Copy the input source unchanged to the output. Mainly useful for
1498 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}
1500 The @var{keep_aspect} parameter is optional, if specified and set to a
1501 non-zero value will force the output display aspect ratio to be the
1502 same of the input, by changing the output sample aspect ratio.
1504 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
1505 expressions containing the following constants:
1509 the computed values for @var{x} and @var{y}. They are evaluated for
1513 the input width and height
1516 same as @var{in_w} and @var{in_h}
1519 the output (cropped) width and height
1522 same as @var{out_w} and @var{out_h}
1525 same as @var{iw} / @var{ih}
1528 input sample aspect ratio
1531 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1534 horizontal and vertical chroma subsample values. For example for the
1535 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1538 the number of input frame, starting from 0
1541 the position in the file of the input frame, NAN if unknown
1544 timestamp expressed in seconds, NAN if the input timestamp is unknown
1548 The @var{out_w} and @var{out_h} parameters specify the expressions for
1549 the width and height of the output (cropped) video. They are
1550 evaluated just at the configuration of the filter.
1552 The default value of @var{out_w} is "in_w", and the default value of
1553 @var{out_h} is "in_h".
1555 The expression for @var{out_w} may depend on the value of @var{out_h},
1556 and the expression for @var{out_h} may depend on @var{out_w}, but they
1557 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
1558 evaluated after @var{out_w} and @var{out_h}.
1560 The @var{x} and @var{y} parameters specify the expressions for the
1561 position of the top-left corner of the output (non-cropped) area. They
1562 are evaluated for each frame. If the evaluated value is not valid, it
1563 is approximated to the nearest valid value.
1565 The default value of @var{x} is "(in_w-out_w)/2", and the default
1566 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
1567 the center of the input image.
1569 The expression for @var{x} may depend on @var{y}, and the expression
1570 for @var{y} may depend on @var{x}.
1572 Follow some examples:
1574 # crop the central input area with size 100x100
1577 # crop the central input area with size 2/3 of the input video
1578 "crop=2/3*in_w:2/3*in_h"
1580 # crop the input video central square
1583 # delimit the rectangle with the top-left corner placed at position
1584 # 100:100 and the right-bottom corner corresponding to the right-bottom
1585 # corner of the input image.
1586 crop=in_w-100:in_h-100:100:100
1588 # crop 10 pixels from the left and right borders, and 20 pixels from
1589 # the top and bottom borders
1590 "crop=in_w-2*10:in_h-2*20"
1592 # keep only the bottom right quarter of the input image
1593 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
1595 # crop height for getting Greek harmony
1596 "crop=in_w:1/PHI*in_w"
1599 "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)"
1601 # erratic camera effect depending on timestamp
1602 "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)"
1604 # set x depending on the value of y
1605 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
1610 Auto-detect crop size.
1612 Calculate necessary cropping parameters and prints the recommended
1613 parameters through the logging system. The detected dimensions
1614 correspond to the non-black area of the input video.
1616 It accepts the syntax:
1618 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
1624 Threshold, which can be optionally specified from nothing (0) to
1625 everything (255), defaults to 24.
1628 Value which the width/height should be divisible by, defaults to
1629 16. The offset is automatically adjusted to center the video. Use 2 to
1630 get only even dimensions (needed for 4:2:2 video). 16 is best when
1631 encoding to most video codecs.
1634 Counter that determines after how many frames cropdetect will reset
1635 the previously detected largest video area and start over to detect
1636 the current optimal crop area. Defaults to 0.
1638 This can be useful when channel logos distort the video area. 0
1639 indicates never reset and return the largest area encountered during
1645 This filter drops frames that do not differ greatly from the previous
1646 frame in order to reduce framerate. The main use of this filter is
1647 for very-low-bitrate encoding (e.g. streaming over dialup modem), but
1648 it could in theory be used for fixing movies that were
1649 inverse-telecined incorrectly.
1651 It accepts the following parameters:
1652 @var{max}:@var{hi}:@var{lo}:@var{frac}.
1657 Set the maximum number of consecutive frames which can be dropped (if
1658 positive), or the minimum interval between dropped frames (if
1659 negative). If the value is 0, the frame is dropped unregarding the
1660 number of previous sequentially dropped frames.
1665 Set the dropping threshold values.
1667 Values for @var{hi} and @var{lo} are for 8x8 pixel blocks and
1668 represent actual pixel value differences, so a threshold of 64
1669 corresponds to 1 unit of difference for each pixel, or the same spread
1670 out differently over the block.
1672 A frame is a candidate for dropping if no 8x8 blocks differ by more
1673 than a threshold of @var{hi}, and if no more than @var{frac} blocks (1
1674 meaning the whole image) differ by more than a threshold of @var{lo}.
1676 Default value for @var{hi} is 64*12, default value for @var{lo} is
1677 64*5, and default value for @var{frac} is 0.33.
1682 Suppress a TV station logo by a simple interpolation of the surrounding
1683 pixels. Just set a rectangle covering the logo and watch it disappear
1684 (and sometimes something even uglier appear - your mileage may vary).
1686 The filter accepts parameters as a string of the form
1687 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
1688 @var{key}=@var{value} pairs, separated by ":".
1690 The description of the accepted parameters follows.
1695 Specify the top left corner coordinates of the logo. They must be
1699 Specify the width and height of the logo to clear. They must be
1703 Specify the thickness of the fuzzy edge of the rectangle (added to
1704 @var{w} and @var{h}). The default value is 4.
1707 When set to 1, a green rectangle is drawn on the screen to simplify
1708 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1709 @var{band} is set to 4. The default value is 0.
1713 Some examples follow.
1718 Set a rectangle covering the area with top left corner coordinates 0,0
1719 and size 100x77, setting a band of size 10:
1721 delogo=0:0:100:77:10
1725 As the previous example, but use named options:
1727 delogo=x=0:y=0:w=100:h=77:band=10
1734 Attempt to fix small changes in horizontal and/or vertical shift. This
1735 filter helps remove camera shake from hand-holding a camera, bumping a
1736 tripod, moving on a vehicle, etc.
1738 The filter accepts parameters as a string of the form
1739 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
1741 A description of the accepted parameters follows.
1746 Specify a rectangular area where to limit the search for motion
1748 If desired the search for motion vectors can be limited to a
1749 rectangular area of the frame defined by its top left corner, width
1750 and height. These parameters have the same meaning as the drawbox
1751 filter which can be used to visualise the position of the bounding
1754 This is useful when simultaneous movement of subjects within the frame
1755 might be confused for camera motion by the motion vector search.
1757 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
1758 then the full frame is used. This allows later options to be set
1759 without specifying the bounding box for the motion vector search.
1761 Default - search the whole frame.
1764 Specify the maximum extent of movement in x and y directions in the
1765 range 0-64 pixels. Default 16.
1768 Specify how to generate pixels to fill blanks at the edge of the
1769 frame. An integer from 0 to 3 as follows:
1772 Fill zeroes at blank locations
1774 Original image at blank locations
1776 Extruded edge value at blank locations
1778 Mirrored edge at blank locations
1781 The default setting is mirror edge at blank locations.
1784 Specify the blocksize to use for motion search. Range 4-128 pixels,
1788 Specify the contrast threshold for blocks. Only blocks with more than
1789 the specified contrast (difference between darkest and lightest
1790 pixels) will be considered. Range 1-255, default 125.
1793 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
1794 search. Default - exhaustive search.
1797 If set then a detailed log of the motion search is written to the
1804 Draw a colored box on the input image.
1806 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1809 The description of the accepted parameters follows.
1813 Specify the top left corner coordinates of the box. Default to 0.
1817 Specify the width and height of the box, if 0 they are interpreted as
1818 the input width and height. Default to 0.
1821 Specify the color of the box to write, it can be the name of a color
1822 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
1823 value @code{invert} is used, the box edge color is the same as the
1824 video with inverted luma.
1827 Set the thickness of the box edge. Default value is @code{4}.
1830 If the key of the first options is omitted, the arguments are
1831 interpreted according to the following syntax:
1833 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}:@var{thickness}
1836 Some examples follow:
1839 Draw a black box around the edge of the input image:
1845 Draw a box with color red and an opacity of 50%:
1847 drawbox=10:20:200:60:red@@0.5
1850 The previous example can be specified as:
1852 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
1856 Fill the box with pink color:
1858 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
1865 Draw text string or text from specified file on top of video using the
1866 libfreetype library.
1868 To enable compilation of this filter you need to configure FFmpeg with
1869 @code{--enable-libfreetype}.
1873 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1876 The description of the accepted parameters follows.
1881 Used to draw a box around text using background color.
1882 Value should be either 1 (enable) or 0 (disable).
1883 The default value of @var{box} is 0.
1886 The color to be used for drawing box around text.
1887 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1888 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1889 The default value of @var{boxcolor} is "white".
1892 Set an expression which specifies if the text should be drawn. If the
1893 expression evaluates to 0, the text is not drawn. This is useful for
1894 specifying that the text should be drawn only when specific conditions
1897 Default value is "1".
1899 See below for the list of accepted constants and functions.
1902 Select how the @var{text} is expanded. Can be either @code{none},
1903 @code{strftime} (default for compatibity reasons but deprecated) or
1904 @code{normal}. See the @ref{drawtext_expansion, Text expansion} section
1908 If true, check and fix text coords to avoid clipping.
1911 The color to be used for drawing fonts.
1912 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1913 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1914 The default value of @var{fontcolor} is "black".
1917 The font file to be used for drawing text. Path must be included.
1918 This parameter is mandatory.
1921 The font size to be used for drawing text.
1922 The default value of @var{fontsize} is 16.
1925 Flags to be used for loading the fonts.
1927 The flags map the corresponding flags supported by libfreetype, and are
1928 a combination of the following values:
1935 @item vertical_layout
1936 @item force_autohint
1939 @item ignore_global_advance_width
1941 @item ignore_transform
1948 Default value is "render".
1950 For more information consult the documentation for the FT_LOAD_*
1954 The color to be used for drawing a shadow behind the drawn text. It
1955 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1956 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1957 The default value of @var{shadowcolor} is "black".
1959 @item shadowx, shadowy
1960 The x and y offsets for the text shadow position with respect to the
1961 position of the text. They can be either positive or negative
1962 values. Default value for both is "0".
1965 The size in number of spaces to use for rendering the tab.
1969 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
1970 format. It can be used with or without text parameter. @var{timecode_rate}
1971 option must be specified.
1973 @item timecode_rate, rate, r
1974 Set the timecode frame rate (timecode only).
1977 The text string to be drawn. The text must be a sequence of UTF-8
1979 This parameter is mandatory if no file is specified with the parameter
1983 A text file containing text to be drawn. The text must be a sequence
1984 of UTF-8 encoded characters.
1986 This parameter is mandatory if no text string is specified with the
1987 parameter @var{text}.
1989 If both @var{text} and @var{textfile} are specified, an error is thrown.
1992 If set to 1, the @var{textfile} will be reloaded before each frame.
1993 Be sure to update it atomically, or it may be read partially, or even fail.
1996 The expressions which specify the offsets where text will be drawn
1997 within the video frame. They are relative to the top/left border of the
2000 The default value of @var{x} and @var{y} is "0".
2002 See below for the list of accepted constants and functions.
2005 The parameters for @var{x} and @var{y} are expressions containing the
2006 following constants and functions:
2010 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2013 horizontal and vertical chroma subsample values. For example for the
2014 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2017 the height of each text line
2025 @item max_glyph_a, ascent
2026 the maximum distance from the baseline to the highest/upper grid
2027 coordinate used to place a glyph outline point, for all the rendered
2029 It is a positive value, due to the grid's orientation with the Y axis
2032 @item max_glyph_d, descent
2033 the maximum distance from the baseline to the lowest grid coordinate
2034 used to place a glyph outline point, for all the rendered glyphs.
2035 This is a negative value, due to the grid's orientation, with the Y axis
2039 maximum glyph height, that is the maximum height for all the glyphs
2040 contained in the rendered text, it is equivalent to @var{ascent} -
2044 maximum glyph width, that is the maximum width for all the glyphs
2045 contained in the rendered text
2048 the number of input frame, starting from 0
2050 @item rand(min, max)
2051 return a random number included between @var{min} and @var{max}
2054 input sample aspect ratio
2057 timestamp expressed in seconds, NAN if the input timestamp is unknown
2060 the height of the rendered text
2063 the width of the rendered text
2066 the x and y offset coordinates where the text is drawn.
2068 These parameters allow the @var{x} and @var{y} expressions to refer
2069 each other, so you can for example specify @code{y=x/dar}.
2072 If libavfilter was built with @code{--enable-fontconfig}, then
2073 @option{fontfile} can be a fontconfig pattern or omitted.
2075 @anchor{drawtext_expansion}
2076 @subsection Text expansion
2078 If @option{expansion} is set to @code{strftime} (which is the default for
2079 now), the filter recognizes strftime() sequences in the provided text and
2080 expands them accordingly. Check the documentation of strftime(). This
2081 feature is deprecated.
2083 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2085 If @option{expansion} is set to @code{normal} (which will be the default),
2086 the following expansion mechanism is used.
2088 The backslash character '\', followed by any character, always expands to
2089 the second character.
2091 Sequence of the form @code{%@{...@}} are expanded. The text between the
2092 braces is a function name, possibly followed by arguments separated by ':'.
2093 If the arguments contain special characters or delimiters (':' or '@}'),
2094 they should be escaped.
2096 Note that they probably must also be escaped as the value for the
2097 @option{text} option in the filter argument string and as the filter
2098 argument in the filter graph description, and possibly also for the shell,
2099 that makes up to four levels of escaping; using a text file avoids these
2102 The following functions are available:
2107 The expression evaluation result.
2109 It must take one argument specifying the expression to be evaluated,
2110 which accepts the same constants and functions as the @var{x} and
2111 @var{y} values. Note that not all constants should be used, for
2112 example the text size is not known when evaluating the expression, so
2113 the constants @var{text_w} and @var{text_h} will have an undefined
2117 The time at which the filter is running, expressed in UTC.
2118 It can accept an argument: a strftime() format string.
2121 The time at which the filter is running, expressed in the local time zone.
2122 It can accept an argument: a strftime() format string.
2125 The frame number, starting from 0.
2128 The timestamp of the current frame, in seconds, with microsecond accuracy.
2132 @subsection Examples
2134 Some examples follow.
2139 Draw "Test Text" with font FreeSerif, using the default values for the
2140 optional parameters.
2143 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2147 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2148 and y=50 (counting from the top-left corner of the screen), text is
2149 yellow with a red box around it. Both the text and the box have an
2153 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2154 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2157 Note that the double quotes are not necessary if spaces are not used
2158 within the parameter list.
2161 Show the text at the center of the video frame:
2163 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2167 Show a text line sliding from right to left in the last row of the video
2168 frame. The file @file{LONG_LINE} is assumed to contain a single line
2171 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2175 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2177 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2181 Draw a single green letter "g", at the center of the input video.
2182 The glyph baseline is placed at half screen height.
2184 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2188 Show text for 1 second every 3 seconds:
2190 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2194 Use fontconfig to set the font. Note that the colons need to be escaped.
2196 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2200 Print the date of a real-time encoding (see strftime(3)):
2202 drawtext='fontfile=FreeSans.ttf:expansion=normal:text=%@{localtime:%a %b %d %Y@}'
2207 For more information about libfreetype, check:
2208 @url{http://www.freetype.org/}.
2210 For more information about fontconfig, check:
2211 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
2215 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
2217 This filter accepts the following optional named parameters:
2221 Set low and high threshold values used by the Canny thresholding
2224 The high threshold selects the "strong" edge pixels, which are then
2225 connected through 8-connectivity with the "weak" edge pixels selected
2226 by the low threshold.
2228 @var{low} and @var{high} threshold values must be choosen in the range
2229 [0,1], and @var{low} should be lesser or equal to @var{high}.
2231 Default value for @var{low} is @code{20/255}, and default value for @var{high}
2237 edgedetect=low=0.1:high=0.4
2242 Apply fade-in/out effect to input video.
2244 It accepts the parameters:
2245 @var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}]
2247 @var{type} specifies if the effect type, can be either "in" for
2248 fade-in, or "out" for a fade-out effect.
2250 @var{start_frame} specifies the number of the start frame for starting
2251 to apply the fade effect.
2253 @var{nb_frames} specifies the number of frames for which the fade
2254 effect has to last. At the end of the fade-in effect the output video
2255 will have the same intensity as the input video, at the end of the
2256 fade-out transition the output video will be completely black.
2258 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
2259 separated by ":". The description of the accepted options follows.
2266 @item start_frame, s
2267 See @var{start_frame}.
2270 See @var{nb_frames}.
2273 If set to 1, fade only alpha channel, if one exists on the input.
2277 A few usage examples follow, usable too as test scenarios.
2279 # fade in first 30 frames of video
2282 # fade out last 45 frames of a 200-frame video
2285 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
2286 fade=in:0:25, fade=out:975:25
2288 # make first 5 frames black, then fade in from frame 5-24
2291 # fade in alpha over first 25 frames of video
2292 fade=in:0:25:alpha=1
2297 Extract a single field from an interlaced image using stride
2298 arithmetic to avoid wasting CPU time. The output frames are marked as
2301 This filter accepts the following named options:
2304 Specify whether to extract the top (if the value is @code{0} or
2305 @code{top}) or the bottom field (if the value is @code{1} or
2309 If the option key is not specified, the first value sets the @var{type}
2310 option. For example:
2322 Transform the field order of the input video.
2324 It accepts one parameter which specifies the required field order that
2325 the input interlaced video will be transformed to. The parameter can
2326 assume one of the following values:
2330 output bottom field first
2332 output top field first
2335 Default value is "tff".
2337 Transformation is achieved by shifting the picture content up or down
2338 by one line, and filling the remaining line with appropriate picture content.
2339 This method is consistent with most broadcast field order converters.
2341 If the input video is not flagged as being interlaced, or it is already
2342 flagged as being of the required output field order then this filter does
2343 not alter the incoming video.
2345 This filter is very useful when converting to or from PAL DV material,
2346 which is bottom field first.
2350 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
2355 Buffer input images and send them when they are requested.
2357 This filter is mainly useful when auto-inserted by the libavfilter
2360 The filter does not take parameters.
2364 Convert the input video to one of the specified pixel formats.
2365 Libavfilter will try to pick one that is supported for the input to
2368 The filter accepts a list of pixel format names, separated by ":",
2369 for example "yuv420p:monow:rgb24".
2371 Some examples follow:
2373 # convert the input video to the format "yuv420p"
2376 # convert the input video to any of the formats in the list
2377 format=yuv420p:yuv444p:yuv410p
2382 Convert the video to specified constant framerate by duplicating or dropping
2383 frames as necessary.
2385 This filter accepts the following named parameters:
2389 Desired output framerate.
2392 Rounding method. The default is @code{near}.
2398 Select one frame every N.
2400 This filter accepts in input a string representing a positive
2401 integer. Default argument is @code{1}.
2406 Apply a frei0r effect to the input video.
2408 To enable compilation of this filter you need to install the frei0r
2409 header and configure FFmpeg with @code{--enable-frei0r}.
2411 The filter supports the syntax:
2413 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
2416 @var{filter_name} is the name of the frei0r effect to load. If the
2417 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
2418 is searched in each one of the directories specified by the colon (or
2419 semicolon on Windows platforms) separated list in @env{FREIOR_PATH},
2420 otherwise in the standard frei0r paths, which are in this order:
2421 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
2422 @file{/usr/lib/frei0r-1/}.
2424 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
2425 for the frei0r effect.
2427 A frei0r effect parameter can be a boolean (whose values are specified
2428 with "y" and "n"), a double, a color (specified by the syntax
2429 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
2430 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
2431 description), a position (specified by the syntax @var{X}/@var{Y},
2432 @var{X} and @var{Y} being float numbers) and a string.
2434 The number and kind of parameters depend on the loaded effect. If an
2435 effect parameter is not specified the default value is set.
2437 Some examples follow:
2441 Apply the distort0r effect, set the first two double parameters:
2443 frei0r=distort0r:0.5:0.01
2447 Apply the colordistance effect, take a color as first parameter:
2449 frei0r=colordistance:0.2/0.3/0.4
2450 frei0r=colordistance:violet
2451 frei0r=colordistance:0x112233
2455 Apply the perspective effect, specify the top left and top right image
2458 frei0r=perspective:0.2/0.2:0.8/0.2
2462 For more information see:
2463 @url{http://frei0r.dyne.org}
2467 The filter takes one, two or three equations as parameter, separated by ':'.
2468 The first equation is mandatory and applies to the luma plane. The two
2469 following are respectively for chroma blue and chroma red planes.
2471 The filter syntax allows named parameters:
2475 the luminance expression
2477 the chrominance blue expression
2479 the chrominance red expression
2482 If one of the chrominance expression is not defined, it falls back on the other
2483 one. If none of them are specified, they will evaluate the luminance
2486 The expressions can use the following variables and functions:
2490 The sequential number of the filtered frame, starting from @code{0}.
2493 The coordinates of the current sample.
2496 The width and height of the image.
2499 Width and height scale depending on the currently filtered plane. It is the
2500 ratio between the corresponding luma plane number of pixels and the current
2501 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2502 @code{0.5,0.5} for chroma planes.
2505 Time of the current frame, expressed in seconds.
2508 Return the value of the pixel at location (@var{x},@var{y}) of the current
2512 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
2516 Return the value of the pixel at location (@var{x},@var{y}) of the
2517 blue-difference chroma plane.
2520 Return the value of the pixel at location (@var{x},@var{y}) of the
2521 red-difference chroma plane.
2524 For functions, if @var{x} and @var{y} are outside the area, the value will be
2525 automatically clipped to the closer edge.
2527 Some examples follow:
2531 Flip the image horizontally:
2537 Generate a bidimensional sine wave, with angle @code{PI/3} and a
2538 wavelength of 100 pixels:
2540 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
2544 Generate a fancy enigmatic moving light:
2546 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
2552 Fix the banding artifacts that are sometimes introduced into nearly flat
2553 regions by truncation to 8bit color depth.
2554 Interpolate the gradients that should go where the bands are, and
2557 This filter is designed for playback only. Do not use it prior to
2558 lossy compression, because compression tends to lose the dither and
2559 bring back the bands.
2561 The filter takes two optional parameters, separated by ':':
2562 @var{strength}:@var{radius}
2564 @var{strength} is the maximum amount by which the filter will change
2565 any one pixel. Also the threshold for detecting nearly flat
2566 regions. Acceptable values range from .51 to 255, default value is
2567 1.2, out-of-range values will be clipped to the valid range.
2569 @var{radius} is the neighborhood to fit the gradient to. A larger
2570 radius makes for smoother gradients, but also prevents the filter from
2571 modifying the pixels near detailed regions. Acceptable values are
2572 8-32, default value is 16, out-of-range values will be clipped to the
2576 # default parameters
2585 Flip the input video horizontally.
2587 For example to horizontally flip the input video with @command{ffmpeg}:
2589 ffmpeg -i in.avi -vf "hflip" out.avi
2594 High precision/quality 3d denoise filter. This filter aims to reduce
2595 image noise producing smooth images and making still images really
2596 still. It should enhance compressibility.
2598 It accepts the following optional parameters:
2599 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
2603 a non-negative float number which specifies spatial luma strength,
2606 @item chroma_spatial
2607 a non-negative float number which specifies spatial chroma strength,
2608 defaults to 3.0*@var{luma_spatial}/4.0
2611 a float number which specifies luma temporal strength, defaults to
2612 6.0*@var{luma_spatial}/4.0
2615 a float number which specifies chroma temporal strength, defaults to
2616 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
2621 Modify the hue and/or the saturation of the input.
2623 This filter accepts the following optional named options:
2627 Specify the hue angle as a number of degrees. It accepts a float
2628 number or an expression, and defaults to 0.0.
2631 Specify the hue angle as a number of degrees. It accepts a float
2632 number or an expression, and defaults to 0.0.
2635 Specify the saturation in the [-10,10] range. It accepts a float number and
2639 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
2640 following constants:
2644 frame count of the input frame starting from 0
2647 presentation timestamp of the input frame expressed in time base units
2650 frame rate of the input video, NAN if the input frame rate is unknown
2653 timestamp expressed in seconds, NAN if the input timestamp is unknown
2656 time base of the input video
2659 The options can also be set using the syntax: @var{hue}:@var{saturation}
2661 In this case @var{hue} is expressed in degrees.
2663 Some examples follow:
2666 Set the hue to 90 degrees and the saturation to 1.0:
2672 Same command but expressing the hue in radians:
2678 Same command without named options, hue must be expressed in degrees:
2684 Note that "h:s" syntax does not support expressions for the values of
2685 h and s, so the following example will issue an error:
2691 Rotate hue and make the saturation swing between 0
2692 and 2 over a period of 1 second:
2694 hue="H=2*PI*t: s=sin(2*PI*t)+1"
2698 Apply a 3 seconds saturation fade-in effect starting at 0:
2703 The general fade-in expression can be written as:
2705 hue="s=min(0\, max((t-START)/DURATION\, 1))"
2709 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
2711 hue="s=max(0\, min(1\, (8-t)/3))"
2714 The general fade-out expression can be written as:
2716 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
2721 @subsection Commands
2723 This filter supports the following command:
2726 Modify the hue and/or the saturation of the input video.
2727 The command accepts the same named options and syntax than when calling the
2728 filter from the command-line.
2730 If a parameter is omitted, it is kept at its current value.
2735 Interlaceing detect filter. This filter tries to detect if the input is
2736 interlaced or progressive. Top or bottom field first.
2738 @section lut, lutrgb, lutyuv
2740 Compute a look-up table for binding each pixel component input value
2741 to an output value, and apply it to input video.
2743 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
2744 to an RGB input video.
2746 These filters accept in input a ":"-separated list of options, which
2747 specify the expressions used for computing the lookup table for the
2748 corresponding pixel component values.
2750 The @var{lut} filter requires either YUV or RGB pixel formats in
2751 input, and accepts the options:
2753 @item @var{c0} (first pixel component)
2754 @item @var{c1} (second pixel component)
2755 @item @var{c2} (third pixel component)
2756 @item @var{c3} (fourth pixel component, corresponds to the alpha component)
2759 The exact component associated to each option depends on the format in
2762 The @var{lutrgb} filter requires RGB pixel formats in input, and
2763 accepts the options:
2765 @item @var{r} (red component)
2766 @item @var{g} (green component)
2767 @item @var{b} (blue component)
2768 @item @var{a} (alpha component)
2771 The @var{lutyuv} filter requires YUV pixel formats in input, and
2772 accepts the options:
2774 @item @var{y} (Y/luminance component)
2775 @item @var{u} (U/Cb component)
2776 @item @var{v} (V/Cr component)
2777 @item @var{a} (alpha component)
2780 The expressions can contain the following constants and functions:
2784 the input width and height
2787 input value for the pixel component
2790 the input value clipped in the @var{minval}-@var{maxval} range
2793 maximum value for the pixel component
2796 minimum value for the pixel component
2799 the negated value for the pixel component value clipped in the
2800 @var{minval}-@var{maxval} range , it corresponds to the expression
2801 "maxval-clipval+minval"
2804 the computed value in @var{val} clipped in the
2805 @var{minval}-@var{maxval} range
2807 @item gammaval(gamma)
2808 the computed gamma correction value of the pixel component value
2809 clipped in the @var{minval}-@var{maxval} range, corresponds to the
2811 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
2815 All expressions default to "val".
2817 Some examples follow:
2819 # negate input video
2820 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
2821 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
2823 # the above is the same as
2824 lutrgb="r=negval:g=negval:b=negval"
2825 lutyuv="y=negval:u=negval:v=negval"
2830 # remove chroma components, turns the video into a graytone image
2831 lutyuv="u=128:v=128"
2833 # apply a luma burning effect
2836 # remove green and blue components
2839 # set a constant alpha channel value on input
2840 format=rgba,lutrgb=a="maxval-minval/2"
2842 # correct luminance gamma by a 0.5 factor
2843 lutyuv=y=gammaval(0.5)
2848 Apply an MPlayer filter to the input video.
2850 This filter provides a wrapper around most of the filters of
2853 This wrapper is considered experimental. Some of the wrapped filters
2854 may not work properly and we may drop support for them, as they will
2855 be implemented natively into FFmpeg. Thus you should avoid
2856 depending on them when writing portable scripts.
2858 The filters accepts the parameters:
2859 @var{filter_name}[:=]@var{filter_params}
2861 @var{filter_name} is the name of a supported MPlayer filter,
2862 @var{filter_params} is a string containing the parameters accepted by
2865 The list of the currently supported filters follows:
2900 The parameter syntax and behavior for the listed filters are the same
2901 of the corresponding MPlayer filters. For detailed instructions check
2902 the "VIDEO FILTERS" section in the MPlayer manual.
2904 Some examples follow:
2907 Adjust gamma, brightness, contrast:
2913 Add temporal noise to input video:
2919 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
2925 This filter accepts an integer in input, if non-zero it negates the
2926 alpha component (if available). The default value in input is 0.
2930 Force libavfilter not to use any of the specified pixel formats for the
2931 input to the next filter.
2933 The filter accepts a list of pixel format names, separated by ":",
2934 for example "yuv420p:monow:rgb24".
2936 Some examples follow:
2938 # force libavfilter to use a format different from "yuv420p" for the
2939 # input to the vflip filter
2940 noformat=yuv420p,vflip
2942 # convert the input video to any of the formats not contained in the list
2943 noformat=yuv420p:yuv444p:yuv410p
2948 Pass the video source unchanged to the output.
2952 Apply video transform using libopencv.
2954 To enable this filter install libopencv library and headers and
2955 configure FFmpeg with @code{--enable-libopencv}.
2957 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
2959 @var{filter_name} is the name of the libopencv filter to apply.
2961 @var{filter_params} specifies the parameters to pass to the libopencv
2962 filter. If not specified the default values are assumed.
2964 Refer to the official libopencv documentation for more precise
2966 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
2968 Follows the list of supported libopencv filters.
2973 Dilate an image by using a specific structuring element.
2974 This filter corresponds to the libopencv function @code{cvDilate}.
2976 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
2978 @var{struct_el} represents a structuring element, and has the syntax:
2979 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
2981 @var{cols} and @var{rows} represent the number of columns and rows of
2982 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
2983 point, and @var{shape} the shape for the structuring element, and
2984 can be one of the values "rect", "cross", "ellipse", "custom".
2986 If the value for @var{shape} is "custom", it must be followed by a
2987 string of the form "=@var{filename}". The file with name
2988 @var{filename} is assumed to represent a binary image, with each
2989 printable character corresponding to a bright pixel. When a custom
2990 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
2991 or columns and rows of the read file are assumed instead.
2993 The default value for @var{struct_el} is "3x3+0x0/rect".
2995 @var{nb_iterations} specifies the number of times the transform is
2996 applied to the image, and defaults to 1.
2998 Follow some example:
3000 # use the default values
3003 # dilate using a structuring element with a 5x5 cross, iterate two times
3004 ocv=dilate=5x5+2x2/cross:2
3006 # read the shape from the file diamond.shape, iterate two times
3007 # the file diamond.shape may contain a pattern of characters like this:
3013 # the specified cols and rows are ignored (but not the anchor point coordinates)
3014 ocv=0x0+2x2/custom=diamond.shape:2
3019 Erode an image by using a specific structuring element.
3020 This filter corresponds to the libopencv function @code{cvErode}.
3022 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
3023 with the same syntax and semantics as the @ref{dilate} filter.
3027 Smooth the input video.
3029 The filter takes the following parameters:
3030 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
3032 @var{type} is the type of smooth filter to apply, and can be one of
3033 the following values: "blur", "blur_no_scale", "median", "gaussian",
3034 "bilateral". The default value is "gaussian".
3036 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
3037 parameters whose meanings depend on smooth type. @var{param1} and
3038 @var{param2} accept integer positive values or 0, @var{param3} and
3039 @var{param4} accept float values.
3041 The default value for @var{param1} is 3, the default value for the
3042 other parameters is 0.
3044 These parameters correspond to the parameters assigned to the
3045 libopencv function @code{cvSmooth}.
3050 Overlay one video on top of another.
3052 It takes two inputs and one output, the first input is the "main"
3053 video on which the second input is overlayed.
3055 It accepts the parameters: @var{x}:@var{y}[:@var{options}].
3057 @var{x} is the x coordinate of the overlayed video on the main video,
3058 @var{y} is the y coordinate. @var{x} and @var{y} are expressions containing
3059 the following parameters:
3062 @item main_w, main_h
3063 main input width and height
3066 same as @var{main_w} and @var{main_h}
3068 @item overlay_w, overlay_h
3069 overlay input width and height
3072 same as @var{overlay_w} and @var{overlay_h}
3075 @var{options} is an optional list of @var{key}=@var{value} pairs,
3078 The description of the accepted options follows.
3082 If set to 1, force the filter to accept inputs in the RGB
3083 color space. Default value is 0.
3086 Be aware that frames are taken from each input video in timestamp
3087 order, hence, if their initial timestamps differ, it is a a good idea
3088 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
3089 have them begin in the same zero timestamp, as it does the example for
3090 the @var{movie} filter.
3092 Follow some examples:
3094 # draw the overlay at 10 pixels from the bottom right
3095 # corner of the main video.
3096 overlay=main_w-overlay_w-10:main_h-overlay_h-10
3098 # insert a transparent PNG logo in the bottom left corner of the input
3099 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
3101 # insert 2 different transparent PNG logos (second logo on bottom
3103 ffmpeg -i input -i logo1 -i logo2 -filter_complex
3104 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
3106 # add a transparent color layer on top of the main video,
3107 # WxH specifies the size of the main input to the overlay filter
3108 color=red@@.3:WxH [over]; [in][over] overlay [out]
3110 # play an original video and a filtered version (here with the deshake filter)
3112 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
3114 # the previous example is the same as:
3115 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
3118 You can chain together more overlays but the efficiency of such
3119 approach is yet to be tested.
3123 Add paddings to the input image, and places the original input at the
3124 given coordinates @var{x}, @var{y}.
3126 It accepts the following parameters:
3127 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
3129 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
3130 expressions containing the following constants:
3134 the input video width and height
3137 same as @var{in_w} and @var{in_h}
3140 the output width and height, that is the size of the padded area as
3141 specified by the @var{width} and @var{height} expressions
3144 same as @var{out_w} and @var{out_h}
3147 x and y offsets as specified by the @var{x} and @var{y}
3148 expressions, or NAN if not yet specified
3151 same as @var{iw} / @var{ih}
3154 input sample aspect ratio
3157 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3160 horizontal and vertical chroma subsample values. For example for the
3161 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3164 Follows the description of the accepted parameters.
3169 Specify the size of the output image with the paddings added. If the
3170 value for @var{width} or @var{height} is 0, the corresponding input size
3171 is used for the output.
3173 The @var{width} expression can reference the value set by the
3174 @var{height} expression, and vice versa.
3176 The default value of @var{width} and @var{height} is 0.
3180 Specify the offsets where to place the input image in the padded area
3181 with respect to the top/left border of the output image.
3183 The @var{x} expression can reference the value set by the @var{y}
3184 expression, and vice versa.
3186 The default value of @var{x} and @var{y} is 0.
3190 Specify the color of the padded area, it can be the name of a color
3191 (case insensitive match) or a 0xRRGGBB[AA] sequence.
3193 The default value of @var{color} is "black".
3197 @subsection Examples
3201 Add paddings with color "violet" to the input video. Output video
3202 size is 640x480, the top-left corner of the input video is placed at
3205 pad=640:480:0:40:violet
3209 Pad the input to get an output with dimensions increased by 3/2,
3210 and put the input video at the center of the padded area:
3212 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
3216 Pad the input to get a squared output with size equal to the maximum
3217 value between the input width and height, and put the input video at
3218 the center of the padded area:
3220 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
3224 Pad the input to get a final w/h ratio of 16:9:
3226 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
3230 In case of anamorphic video, in order to set the output display aspect
3231 correctly, it is necessary to use @var{sar} in the expression,
3232 according to the relation:
3234 (ih * X / ih) * sar = output_dar
3235 X = output_dar / sar
3238 Thus the previous example needs to be modified to:
3240 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
3244 Double output size and put the input video in the bottom-right
3245 corner of the output padded area:
3247 pad="2*iw:2*ih:ow-iw:oh-ih"
3251 @section pixdesctest
3253 Pixel format descriptor test filter, mainly useful for internal
3254 testing. The output video should be equal to the input video.
3258 format=monow, pixdesctest
3261 can be used to test the monowhite pixel format descriptor definition.
3265 Suppress a TV station logo, using an image file to determine which
3266 pixels comprise the logo. It works by filling in the pixels that
3267 comprise the logo with neighboring pixels.
3269 This filter requires one argument which specifies the filter bitmap
3270 file, which can be any image format supported by libavformat. The
3271 width and height of the image file must match those of the video
3272 stream being processed.
3274 Pixels in the provided bitmap image with a value of zero are not
3275 considered part of the logo, non-zero pixels are considered part of
3276 the logo. If you use white (255) for the logo and black (0) for the
3277 rest, you will be safe. For making the filter bitmap, it is
3278 recommended to take a screen capture of a black frame with the logo
3279 visible, and then using a threshold filter followed by the erode
3280 filter once or twice.
3282 If needed, little splotches can be fixed manually. Remember that if
3283 logo pixels are not covered, the filter quality will be much
3284 reduced. Marking too many pixels as part of the logo does not hurt as
3285 much, but it will increase the amount of blurring needed to cover over
3286 the image and will destroy more information than necessary, and extra
3287 pixels will slow things down on a large logo.
3291 Scale (resize) the input video, using the libswscale library.
3293 The scale filter forces the output display aspect ratio to be the same
3294 of the input, by changing the output sample aspect ratio.
3296 This filter accepts a list of named options in the form of
3297 @var{key}=@var{value} pairs separated by ":". If the key for the first
3298 two options is not specified, the assumed keys for the first two
3299 values are @code{w} and @code{h}. If the first option has no key and
3300 can be interpreted like a video size specification, it will be used
3301 to set the video size.
3303 A description of the accepted options follows.
3307 Set the video width expression, default value is @code{iw}. See below
3308 for the list of accepted constants.
3311 Set the video heiht expression, default value is @code{ih}.
3312 See below for the list of accepted constants.
3315 Set the interlacing. It accepts the following values:
3319 force interlaced aware scaling
3322 do not apply interlaced scaling
3325 select interlaced aware scaling depending on whether the source frames
3326 are flagged as interlaced or not
3329 Default value is @code{0}.
3332 Set libswscale scaling flags. If not explictly specified the filter
3333 applies a bilinear scaling algorithm.
3336 Set the video size, the value must be a valid abbreviation or in the
3337 form @var{width}x@var{height}.
3340 The values of the @var{w} and @var{h} options are expressions
3341 containing the following constants:
3345 the input width and height
3348 same as @var{in_w} and @var{in_h}
3351 the output (cropped) width and height
3354 same as @var{out_w} and @var{out_h}
3357 same as @var{iw} / @var{ih}
3360 input sample aspect ratio
3363 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3366 horizontal and vertical chroma subsample values. For example for the
3367 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3370 If the input image format is different from the format requested by
3371 the next filter, the scale filter will convert the input to the
3374 If the value for @var{width} or @var{height} is 0, the respective input
3375 size is used for the output.
3377 If the value for @var{width} or @var{height} is -1, the scale filter will
3378 use, for the respective output size, a value that maintains the aspect
3379 ratio of the input image.
3381 @subsection Examples
3385 Scale the input video to a size of 200x100:
3390 This is equivalent to:
3401 Specify a size abbreviation for the output size:
3406 which can also be written as:
3412 Scale the input to 2x:
3418 The above is the same as:
3424 Scale the input to 2x with forced interlaced scaling:
3426 scale=2*iw:2*ih:interl=1
3430 Scale the input to half size:
3436 Increase the width, and set the height to the same size:
3442 Seek for Greek harmony:
3449 Increase the height, and set the width to 3/2 of the height:
3455 Increase the size, but make the size a multiple of the chroma:
3457 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
3461 Increase the width to a maximum of 500 pixels, keep the same input
3464 scale='min(500\, iw*3/2):-1'
3469 Select frames to pass in output.
3471 It accepts in input an expression, which is evaluated for each input
3472 frame. If the expression is evaluated to a non-zero value, the frame
3473 is selected and passed to the output, otherwise it is discarded.
3475 The expression can contain the following constants:
3479 the sequential number of the filtered frame, starting from 0
3482 the sequential number of the selected frame, starting from 0
3484 @item prev_selected_n
3485 the sequential number of the last selected frame, NAN if undefined
3488 timebase of the input timestamps
3491 the PTS (Presentation TimeStamp) of the filtered video frame,
3492 expressed in @var{TB} units, NAN if undefined
3495 the PTS (Presentation TimeStamp) of the filtered video frame,
3496 expressed in seconds, NAN if undefined
3499 the PTS of the previously filtered video frame, NAN if undefined
3501 @item prev_selected_pts
3502 the PTS of the last previously filtered video frame, NAN if undefined
3504 @item prev_selected_t
3505 the PTS of the last previously selected video frame, NAN if undefined
3508 the PTS of the first video frame in the video, NAN if undefined
3511 the time of the first video frame in the video, NAN if undefined
3514 the type of the filtered frame, can assume one of the following
3526 @item interlace_type
3527 the frame interlace type, can assume one of the following values:
3530 the frame is progressive (not interlaced)
3532 the frame is top-field-first
3534 the frame is bottom-field-first
3538 1 if the filtered frame is a key-frame, 0 otherwise
3541 the position in the file of the filtered frame, -1 if the information
3542 is not available (e.g. for synthetic video)
3545 value between 0 and 1 to indicate a new scene; a low value reflects a low
3546 probability for the current frame to introduce a new scene, while a higher
3547 value means the current frame is more likely to be one (see the example below)
3551 The default value of the select expression is "1".
3553 Some examples follow:
3556 # select all frames in input
3559 # the above is the same as:
3565 # select only I-frames
3566 select='eq(pict_type\,I)'
3568 # select one frame every 100
3569 select='not(mod(n\,100))'
3571 # select only frames contained in the 10-20 time interval
3572 select='gte(t\,10)*lte(t\,20)'
3574 # select only I frames contained in the 10-20 time interval
3575 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
3577 # select frames with a minimum distance of 10 seconds
3578 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
3581 Complete example to create a mosaic of the first scenes:
3584 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
3587 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
3590 @section setdar, setsar
3592 The @code{setdar} filter sets the Display Aspect Ratio for the filter
3595 This is done by changing the specified Sample (aka Pixel) Aspect
3596 Ratio, according to the following equation:
3598 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
3601 Keep in mind that the @code{setdar} filter does not modify the pixel
3602 dimensions of the video frame. Also the display aspect ratio set by
3603 this filter may be changed by later filters in the filterchain,
3604 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
3607 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
3608 the filter output video.
3610 Note that as a consequence of the application of this filter, the
3611 output display aspect ratio will change according to the equation
3614 Keep in mind that the sample aspect ratio set by the @code{setsar}
3615 filter may be changed by later filters in the filterchain, e.g. if
3616 another "setsar" or a "setdar" filter is applied.
3618 The @code{setdar} and @code{setsar} filters accept a string in the
3619 form @var{num}:@var{den} expressing an aspect ratio, or the following
3620 named options, expressed as a sequence of @var{key}=@var{value} pairs,
3625 Set the maximum integer value to use for expressing numerator and
3626 denominator when reducing the expressed aspect ratio to a rational.
3627 Default value is @code{100}.
3630 Set the aspect ratio used by the filter.
3632 The parameter can be a floating point number string, an expression, or
3633 a string of the form @var{num}:@var{den}, where @var{num} and
3634 @var{den} are the numerator and denominator of the aspect ratio. If
3635 the parameter is not specified, it is assumed the value "0".
3636 In case the form "@var{num}:@var{den}" the @code{:} character should
3640 If the keys are omitted in the named options list, the specifed values
3641 are assumed to be @var{ratio} and @var{max} in that order.
3643 For example to change the display aspect ratio to 16:9, specify:
3648 The example above is equivalent to:
3653 To change the sample aspect ratio to 10:11, specify:
3658 To set a display aspect ratio of 16:9, and specify a maximum integer value of
3659 1000 in the aspect ratio reduction, use the command:
3661 setdar=ratio='16:9':max=1000
3666 Force field for the output video frame.
3668 The @code{setfield} filter marks the interlace type field for the
3669 output frames. It does not change the input frame, but only sets the
3670 corresponding property, which affects how the frame is treated by
3671 following filters (e.g. @code{fieldorder} or @code{yadif}).
3673 It accepts a string parameter, which can assume the following values:
3676 Keep the same field property.
3679 Mark the frame as bottom-field-first.
3682 Mark the frame as top-field-first.
3685 Mark the frame as progressive.
3690 Show a line containing various information for each input video frame.
3691 The input video is not modified.
3693 The shown line contains a sequence of key/value pairs of the form
3694 @var{key}:@var{value}.
3696 A description of each shown parameter follows:
3700 sequential number of the input frame, starting from 0
3703 Presentation TimeStamp of the input frame, expressed as a number of
3704 time base units. The time base unit depends on the filter input pad.
3707 Presentation TimeStamp of the input frame, expressed as a number of
3711 position of the frame in the input stream, -1 if this information in
3712 unavailable and/or meaningless (for example in case of synthetic video)
3718 sample aspect ratio of the input frame, expressed in the form
3722 size of the input frame, expressed in the form
3723 @var{width}x@var{height}
3726 interlaced mode ("P" for "progressive", "T" for top field first, "B"
3727 for bottom field first)
3730 1 if the frame is a key frame, 0 otherwise
3733 picture type of the input frame ("I" for an I-frame, "P" for a
3734 P-frame, "B" for a B-frame, "?" for unknown type).
3735 Check also the documentation of the @code{AVPictureType} enum and of
3736 the @code{av_get_picture_type_char} function defined in
3737 @file{libavutil/avutil.h}.
3740 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
3742 @item plane_checksum
3743 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
3744 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
3749 Blur the input video without impacting the outlines.
3751 The filter accepts the following parameters:
3752 @var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
3754 Parameters prefixed by @var{luma} indicate that they work on the
3755 luminance of the pixels whereas parameters prefixed by @var{chroma}
3756 refer to the chrominance of the pixels.
3758 If the chroma parameters are not set, the luma parameters are used for
3759 either the luminance and the chrominance of the pixels.
3761 @var{luma_radius} or @var{chroma_radius} must be a float number in the
3762 range [0.1,5.0] that specifies the variance of the gaussian filter
3763 used to blur the image (slower if larger).
3765 @var{luma_strength} or @var{chroma_strength} must be a float number in
3766 the range [-1.0,1.0] that configures the blurring. A value included in
3767 [0.0,1.0] will blur the image whereas a value included in [-1.0,0.0]
3768 will sharpen the image.
3770 @var{luma_threshold} or @var{chroma_threshold} must be an integer in
3771 the range [-30,30] that is used as a coefficient to determine whether
3772 a pixel should be blurred or not. A value of 0 will filter all the
3773 image, a value included in [0,30] will filter flat areas and a value
3774 included in [-30,0] will filter edges.
3779 Draw subtitles on top of input video using the libass library.
3781 To enable compilation of this filter you need to configure FFmpeg with
3782 @code{--enable-libass}. This filter also requires a build with libavcodec and
3783 libavformat to convert the passed subtitles file to ASS (Advanced Substation
3784 Alpha) subtitles format.
3786 This filter accepts the following named options, expressed as a
3787 sequence of @var{key}=@var{value} pairs, separated by ":".
3791 Set the filename of the subtitle file to read. It must be specified.
3794 Specify the size of the original video, the video for which the ASS file
3795 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
3796 necessary to correctly scale the fonts if the aspect ratio has been changed.
3799 If the first key is not specified, it is assumed that the first value
3800 specifies the @option{filename}.
3802 For example, to render the file @file{sub.srt} on top of the input
3803 video, use the command:
3808 which is equivalent to:
3810 subtitles=filename=sub.srt
3815 Split input video into several identical outputs.
3817 The filter accepts a single parameter which specifies the number of outputs. If
3818 unspecified, it defaults to 2.
3822 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
3824 will create 5 copies of the input video.
3828 [in] split [splitout1][splitout2];
3829 [splitout1] crop=100:100:0:0 [cropout];
3830 [splitout2] pad=200:200:100:100 [padout];
3833 will create two separate outputs from the same input, one cropped and
3838 Scale the input by 2x and smooth using the Super2xSaI (Scale and
3839 Interpolate) pixel art scaling algorithm.
3841 Useful for enlarging pixel art images without reducing sharpness.
3847 Select the most representative frame in a given sequence of consecutive frames.
3849 It accepts as argument the frames batch size to analyze (default @var{N}=100);
3850 in a set of @var{N} frames, the filter will pick one of them, and then handle
3851 the next batch of @var{N} frames until the end.
3853 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
3854 value will result in a higher memory usage, so a high value is not recommended.
3856 The following example extract one picture each 50 frames:
3861 Complete example of a thumbnail creation with @command{ffmpeg}:
3863 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
3868 Tile several successive frames together.
3870 It accepts a list of options in the form of @var{key}=@var{value} pairs
3871 separated by ":". A description of the accepted options follows.
3876 Set the grid size (i.e. the number of lines and columns) in the form
3880 Set the outer border margin in pixels.
3883 Set the inner border thickness (i.e. the number of pixels between frames). For
3884 more advanced padding options (such as having different values for the edges),
3885 refer to the pad video filter.
3888 Set the maximum number of frames to render in the given area. It must be less
3889 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
3890 the area will be used.
3894 Alternatively, the options can be specified as a flat string:
3896 @var{layout}[:@var{nb_frames}[:@var{margin}[:@var{padding}]]]
3898 For example, produce 8×8 PNG tiles of all keyframes (@option{-skip_frame
3901 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
3903 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
3904 duplicating each output frame to accomodate the originally detected frame
3907 Another example to display @code{5} pictures in an area of @code{3x2} frames,
3908 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
3909 mixed flat and named options:
3911 tile=3x2:nb_frames=5:padding=7:margin=2
3916 Perform various types of temporal field interlacing.
3918 Frames are counted starting from 1, so the first input frame is
3921 This filter accepts a single option @option{mode} specifying the mode,
3922 which can be specified either by specyfing @code{mode=VALUE} either
3923 specifying the value alone. Available values are:
3927 Move odd frames into the upper field, even into the lower field,
3928 generating a double height frame at half framerate.
3931 Only output even frames, odd frames are dropped, generating a frame with
3932 unchanged height at half framerate.
3935 Only output odd frames, even frames are dropped, generating a frame with
3936 unchanged height at half framerate.
3939 Expand each frame to full height, but pad alternate lines with black,
3940 generating a frame with double height at the same input framerate.
3942 @item interleave_top, 4
3943 Interleave the upper field from odd frames with the lower field from
3944 even frames, generating a frame with unchanged height at half framerate.
3946 @item interleave_bottom, 5
3947 Interleave the lower field from odd frames with the upper field from
3948 even frames, generating a frame with unchanged height at half framerate.
3950 @item interlacex2, 6
3951 Double frame rate with unchanged height. Frames are inserted each
3952 containing the second temporal field from the previous input frame and
3953 the first temporal field from the next input frame. This mode relies on
3954 the top_field_first flag. Useful for interlaced video displays with no
3955 field synchronisation.
3958 Numeric values are deprecated but are accepted for backward
3959 compatibility reasons.
3961 Default mode is @code{merge}.
3965 Transpose rows with columns in the input video and optionally flip it.
3967 This filter accepts the following named parameters:
3971 Specify the transposition direction. Can assume the following values:
3975 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
3983 Rotate by 90 degrees clockwise, that is:
3991 Rotate by 90 degrees counterclockwise, that is:
3999 Rotate by 90 degrees clockwise and vertically flip, that is:
4007 For values between 4-7, the transposition is only done if the input
4008 video geometry is portrait and not landscape. These values are
4009 deprecated, the @code{passthrough} option should be used instead.
4012 Do not apply the transposition if the input geometry matches the one
4013 specified by the specified value. It accepts the following values:
4016 Always apply transposition.
4018 Preserve portrait geometry (when @var{height} >= @var{width}).
4020 Preserve landscape geometry (when @var{width} >= @var{height}).
4023 Default value is @code{none}.
4028 Sharpen or blur the input video.
4030 It accepts the following parameters:
4031 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
4033 Negative values for the amount will blur the input video, while positive
4034 values will sharpen. All parameters are optional and default to the
4035 equivalent of the string '5:5:1.0:5:5:0.0'.
4040 Set the luma matrix horizontal size. It can be an integer between 3
4041 and 13, default value is 5.
4044 Set the luma matrix vertical size. It can be an integer between 3
4045 and 13, default value is 5.
4048 Set the luma effect strength. It can be a float number between -2.0
4049 and 5.0, default value is 1.0.
4051 @item chroma_msize_x
4052 Set the chroma matrix horizontal size. It can be an integer between 3
4053 and 13, default value is 5.
4055 @item chroma_msize_y
4056 Set the chroma matrix vertical size. It can be an integer between 3
4057 and 13, default value is 5.
4060 Set the chroma effect strength. It can be a float number between -2.0
4061 and 5.0, default value is 0.0.
4066 # Strong luma sharpen effect parameters
4069 # Strong blur of both luma and chroma parameters
4070 unsharp=7:7:-2:7:7:-2
4072 # Use the default values with @command{ffmpeg}
4073 ffmpeg -i in.avi -vf "unsharp" out.mp4
4078 Flip the input video vertically.
4081 ffmpeg -i in.avi -vf "vflip" out.avi
4086 Deinterlace the input video ("yadif" means "yet another deinterlacing
4089 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
4091 @var{mode} specifies the interlacing mode to adopt, accepts one of the
4096 output 1 frame for each frame
4098 output 1 frame for each field
4100 like 0 but skips spatial interlacing check
4102 like 1 but skips spatial interlacing check
4107 @var{parity} specifies the picture field parity assumed for the input
4108 interlaced video, accepts one of the following values:
4112 assume top field first
4114 assume bottom field first
4116 enable automatic detection
4119 Default value is -1.
4120 If interlacing is unknown or decoder does not export this information,
4121 top field first will be assumed.
4123 @var{auto} specifies if deinterlacer should trust the interlaced flag
4124 and only deinterlace frames marked as interlaced
4128 deinterlace all frames
4130 only deinterlace frames marked as interlaced
4135 @c man end VIDEO FILTERS
4137 @chapter Video Sources
4138 @c man begin VIDEO SOURCES
4140 Below is a description of the currently available video sources.
4144 Buffer video frames, and make them available to the filter chain.
4146 This source is mainly intended for a programmatic use, in particular
4147 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
4149 It accepts a list of options in the form of @var{key}=@var{value} pairs
4150 separated by ":". A description of the accepted options follows.
4155 Specify the size (width and height) of the buffered video frames.
4158 A string representing the pixel format of the buffered video frames.
4159 It may be a number corresponding to a pixel format, or a pixel format
4163 Specify the timebase assumed by the timestamps of the buffered frames.
4166 Specify the frame rate expected for the video stream.
4169 Specify the sample aspect ratio assumed by the video frames.
4172 Specify the optional parameters to be used for the scale filter which
4173 is automatically inserted when an input change is detected in the
4174 input size or format.
4179 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
4182 will instruct the source to accept video frames with size 320x240 and
4183 with format "yuv410p", assuming 1/24 as the timestamps timebase and
4184 square pixels (1:1 sample aspect ratio).
4185 Since the pixel format with name "yuv410p" corresponds to the number 6
4186 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
4187 this example corresponds to:
4189 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
4192 Alternatively, the options can be specified as a flat string, but this
4193 syntax is deprecated:
4195 @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}]
4199 Create a pattern generated by an elementary cellular automaton.
4201 The initial state of the cellular automaton can be defined through the
4202 @option{filename}, and @option{pattern} options. If such options are
4203 not specified an initial state is created randomly.
4205 At each new frame a new row in the video is filled with the result of
4206 the cellular automaton next generation. The behavior when the whole
4207 frame is filled is defined by the @option{scroll} option.
4209 This source accepts a list of options in the form of
4210 @var{key}=@var{value} pairs separated by ":". A description of the
4211 accepted options follows.
4215 Read the initial cellular automaton state, i.e. the starting row, from
4217 In the file, each non-whitespace character is considered an alive
4218 cell, a newline will terminate the row, and further characters in the
4219 file will be ignored.
4222 Read the initial cellular automaton state, i.e. the starting row, from
4223 the specified string.
4225 Each non-whitespace character in the string is considered an alive
4226 cell, a newline will terminate the row, and further characters in the
4227 string will be ignored.
4230 Set the video rate, that is the number of frames generated per second.
4233 @item random_fill_ratio, ratio
4234 Set the random fill ratio for the initial cellular automaton row. It
4235 is a floating point number value ranging from 0 to 1, defaults to
4238 This option is ignored when a file or a pattern is specified.
4240 @item random_seed, seed
4241 Set the seed for filling randomly the initial row, must be an integer
4242 included between 0 and UINT32_MAX. If not specified, or if explicitly
4243 set to -1, the filter will try to use a good random seed on a best
4247 Set the cellular automaton rule, it is a number ranging from 0 to 255.
4248 Default value is 110.
4251 Set the size of the output video.
4253 If @option{filename} or @option{pattern} is specified, the size is set
4254 by default to the width of the specified initial state row, and the
4255 height is set to @var{width} * PHI.
4257 If @option{size} is set, it must contain the width of the specified
4258 pattern string, and the specified pattern will be centered in the
4261 If a filename or a pattern string is not specified, the size value
4262 defaults to "320x518" (used for a randomly generated initial state).
4265 If set to 1, scroll the output upward when all the rows in the output
4266 have been already filled. If set to 0, the new generated row will be
4267 written over the top row just after the bottom row is filled.
4270 @item start_full, full
4271 If set to 1, completely fill the output with generated rows before
4272 outputting the first frame.
4273 This is the default behavior, for disabling set the value to 0.
4276 If set to 1, stitch the left and right row edges together.
4277 This is the default behavior, for disabling set the value to 0.
4280 @subsection Examples
4284 Read the initial state from @file{pattern}, and specify an output of
4287 cellauto=f=pattern:s=200x400
4291 Generate a random initial row with a width of 200 cells, with a fill
4294 cellauto=ratio=2/3:s=200x200
4298 Create a pattern generated by rule 18 starting by a single alive cell
4299 centered on an initial row with width 100:
4301 cellauto=p=@@:s=100x400:full=0:rule=18
4305 Specify a more elaborated initial pattern:
4307 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
4314 Generate a Mandelbrot set fractal, and progressively zoom towards the
4315 point specified with @var{start_x} and @var{start_y}.
4317 This source accepts a list of options in the form of
4318 @var{key}=@var{value} pairs separated by ":". A description of the
4319 accepted options follows.
4324 Set the terminal pts value. Default value is 400.
4327 Set the terminal scale value.
4328 Must be a floating point value. Default value is 0.3.
4331 Set the inner coloring mode, that is the algorithm used to draw the
4332 Mandelbrot fractal internal region.
4334 It shall assume one of the following values:
4339 Show time until convergence.
4341 Set color based on point closest to the origin of the iterations.
4346 Default value is @var{mincol}.
4349 Set the bailout value. Default value is 10.0.
4352 Set the maximum of iterations performed by the rendering
4353 algorithm. Default value is 7189.
4356 Set outer coloring mode.
4357 It shall assume one of following values:
4359 @item iteration_count
4360 Set iteration cound mode.
4361 @item normalized_iteration_count
4362 set normalized iteration count mode.
4364 Default value is @var{normalized_iteration_count}.
4367 Set frame rate, expressed as number of frames per second. Default
4371 Set frame size. Default value is "640x480".
4374 Set the initial scale value. Default value is 3.0.
4377 Set the initial x position. Must be a floating point value between
4378 -100 and 100. Default value is -0.743643887037158704752191506114774.
4381 Set the initial y position. Must be a floating point value between
4382 -100 and 100. Default value is -0.131825904205311970493132056385139.
4387 Generate various test patterns, as generated by the MPlayer test filter.
4389 The size of the generated video is fixed, and is 256x256.
4390 This source is useful in particular for testing encoding features.
4392 This source accepts an optional sequence of @var{key}=@var{value} pairs,
4393 separated by ":". The description of the accepted options follows.
4398 Specify the frame rate of the sourced video, as the number of frames
4399 generated per second. It has to be a string in the format
4400 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
4401 number or a valid video frame rate abbreviation. The default value is
4405 Set the video duration of the sourced video. The accepted syntax is:
4410 See also the function @code{av_parse_time()}.
4412 If not specified, or the expressed duration is negative, the video is
4413 supposed to be generated forever.
4417 Set the number or the name of the test to perform. Supported tests are:
4432 Default value is "all", which will cycle through the list of all tests.
4435 For example the following:
4440 will generate a "dc_luma" test pattern.
4444 Provide a frei0r source.
4446 To enable compilation of this filter you need to install the frei0r
4447 header and configure FFmpeg with @code{--enable-frei0r}.
4449 The source supports the syntax:
4451 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
4454 @var{size} is the size of the video to generate, may be a string of the
4455 form @var{width}x@var{height} or a frame size abbreviation.
4456 @var{rate} is the rate of the video to generate, may be a string of
4457 the form @var{num}/@var{den} or a frame rate abbreviation.
4458 @var{src_name} is the name to the frei0r source to load. For more
4459 information regarding frei0r and how to set the parameters read the
4460 section @ref{frei0r} in the description of the video filters.
4462 For example, to generate a frei0r partik0l source with size 200x200
4463 and frame rate 10 which is overlayed on the overlay filter main input:
4465 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
4470 Generate a life pattern.
4472 This source is based on a generalization of John Conway's life game.
4474 The sourced input represents a life grid, each pixel represents a cell
4475 which can be in one of two possible states, alive or dead. Every cell
4476 interacts with its eight neighbours, which are the cells that are
4477 horizontally, vertically, or diagonally adjacent.
4479 At each interaction the grid evolves according to the adopted rule,
4480 which specifies the number of neighbor alive cells which will make a
4481 cell stay alive or born. The @option{rule} option allows to specify
4484 This source accepts a list of options in the form of
4485 @var{key}=@var{value} pairs separated by ":". A description of the
4486 accepted options follows.
4490 Set the file from which to read the initial grid state. In the file,
4491 each non-whitespace character is considered an alive cell, and newline
4492 is used to delimit the end of each row.
4494 If this option is not specified, the initial grid is generated
4498 Set the video rate, that is the number of frames generated per second.
4501 @item random_fill_ratio, ratio
4502 Set the random fill ratio for the initial random grid. It is a
4503 floating point number value ranging from 0 to 1, defaults to 1/PHI.
4504 It is ignored when a file is specified.
4506 @item random_seed, seed
4507 Set the seed for filling the initial random grid, must be an integer
4508 included between 0 and UINT32_MAX. If not specified, or if explicitly
4509 set to -1, the filter will try to use a good random seed on a best
4515 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
4516 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
4517 @var{NS} specifies the number of alive neighbor cells which make a
4518 live cell stay alive, and @var{NB} the number of alive neighbor cells
4519 which make a dead cell to become alive (i.e. to "born").
4520 "s" and "b" can be used in place of "S" and "B", respectively.
4522 Alternatively a rule can be specified by an 18-bits integer. The 9
4523 high order bits are used to encode the next cell state if it is alive
4524 for each number of neighbor alive cells, the low order bits specify
4525 the rule for "borning" new cells. Higher order bits encode for an
4526 higher number of neighbor cells.
4527 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
4528 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
4530 Default value is "S23/B3", which is the original Conway's game of life
4531 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
4532 cells, and will born a new cell if there are three alive cells around
4536 Set the size of the output video.
4538 If @option{filename} is specified, the size is set by default to the
4539 same size of the input file. If @option{size} is set, it must contain
4540 the size specified in the input file, and the initial grid defined in
4541 that file is centered in the larger resulting area.
4543 If a filename is not specified, the size value defaults to "320x240"
4544 (used for a randomly generated initial grid).
4547 If set to 1, stitch the left and right grid edges together, and the
4548 top and bottom edges also. Defaults to 1.
4551 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
4552 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
4553 value from 0 to 255.
4556 Set the color of living (or new born) cells.
4559 Set the color of dead cells. If @option{mold} is set, this is the first color
4560 used to represent a dead cell.
4563 Set mold color, for definitely dead and moldy cells.
4566 @subsection Examples
4570 Read a grid from @file{pattern}, and center it on a grid of size
4573 life=f=pattern:s=300x300
4577 Generate a random grid of size 200x200, with a fill ratio of 2/3:
4579 life=ratio=2/3:s=200x200
4583 Specify a custom rule for evolving a randomly generated grid:
4589 Full example with slow death effect (mold) using @command{ffplay}:
4591 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
4595 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
4597 The @code{color} source provides an uniformly colored input.
4599 The @code{nullsrc} source returns unprocessed video frames. It is
4600 mainly useful to be employed in analysis / debugging tools, or as the
4601 source for filters which ignore the input data.
4603 The @code{rgbtestsrc} source generates an RGB test pattern useful for
4604 detecting RGB vs BGR issues. You should see a red, green and blue
4605 stripe from top to bottom.
4607 The @code{smptebars} source generates a color bars pattern, based on
4608 the SMPTE Engineering Guideline EG 1-1990.
4610 The @code{testsrc} source generates a test video pattern, showing a
4611 color pattern, a scrolling gradient and a timestamp. This is mainly
4612 intended for testing purposes.
4614 These sources accept an optional sequence of @var{key}=@var{value} pairs,
4615 separated by ":". The description of the accepted options follows.
4620 Specify the color of the source, only used in the @code{color}
4621 source. It can be the name of a color (case insensitive match) or a
4622 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
4623 default value is "black".
4626 Specify the size of the sourced video, it may be a string of the form
4627 @var{width}x@var{height}, or the name of a size abbreviation. The
4628 default value is "320x240".
4631 Specify the frame rate of the sourced video, as the number of frames
4632 generated per second. It has to be a string in the format
4633 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
4634 number or a valid video frame rate abbreviation. The default value is
4638 Set the sample aspect ratio of the sourced video.
4641 Set the video duration of the sourced video. The accepted syntax is:
4643 [-]HH[:MM[:SS[.m...]]]
4646 See also the function @code{av_parse_time()}.
4648 If not specified, or the expressed duration is negative, the video is
4649 supposed to be generated forever.
4652 Set the number of decimals to show in the timestamp, only used in the
4653 @code{testsrc} source.
4655 The displayed timestamp value will correspond to the original
4656 timestamp value multiplied by the power of 10 of the specified
4657 value. Default value is 0.
4660 For example the following:
4662 testsrc=duration=5.3:size=qcif:rate=10
4665 will generate a video with a duration of 5.3 seconds, with size
4666 176x144 and a frame rate of 10 frames per second.
4668 The following graph description will generate a red source
4669 with an opacity of 0.2, with size "qcif" and a frame rate of 10
4672 color=c=red@@0.2:s=qcif:r=10
4675 If the input content is to be ignored, @code{nullsrc} can be used. The
4676 following command generates noise in the luminance plane by employing
4677 the @code{geq} filter:
4679 nullsrc=s=256x256, geq=random(1)*255:128:128
4682 @c man end VIDEO SOURCES
4684 @chapter Video Sinks
4685 @c man begin VIDEO SINKS
4687 Below is a description of the currently available video sinks.
4691 Buffer video frames, and make them available to the end of the filter
4694 This sink is mainly intended for a programmatic use, in particular
4695 through the interface defined in @file{libavfilter/buffersink.h}.
4697 It does not require a string parameter in input, but you need to
4698 specify a pointer to a list of supported pixel formats terminated by
4699 -1 in the opaque parameter provided to @code{avfilter_init_filter}
4700 when initializing this sink.
4704 Null video sink, do absolutely nothing with the input video. It is
4705 mainly useful as a template and to be employed in analysis / debugging
4708 @c man end VIDEO SINKS
4710 @chapter Multimedia Filters
4711 @c man begin MULTIMEDIA FILTERS
4713 Below is a description of the currently available multimedia filters.
4715 @section asendcmd, sendcmd
4717 Send commands to filters in the filtergraph.
4719 These filters read commands to be sent to other filters in the
4722 @code{asendcmd} must be inserted between two audio filters,
4723 @code{sendcmd} must be inserted between two video filters, but apart
4724 from that they act the same way.
4726 The specification of commands can be provided in the filter arguments
4727 with the @var{commands} option, or in a file specified by the
4728 @var{filename} option.
4730 These filters accept the following options:
4733 Set the commands to be read and sent to the other filters.
4735 Set the filename of the commands to be read and sent to the other
4739 @subsection Commands syntax
4741 A commands description consists of a sequence of interval
4742 specifications, comprising a list of commands to be executed when a
4743 particular event related to that interval occurs. The occurring event
4744 is typically the current frame time entering or leaving a given time
4747 An interval is specified by the following syntax:
4749 @var{START}[-@var{END}] @var{COMMANDS};
4752 The time interval is specified by the @var{START} and @var{END} times.
4753 @var{END} is optional and defaults to the maximum time.
4755 The current frame time is considered within the specified interval if
4756 it is included in the interval [@var{START}, @var{END}), that is when
4757 the time is greater or equal to @var{START} and is lesser than
4760 @var{COMMANDS} consists of a sequence of one or more command
4761 specifications, separated by ",", relating to that interval. The
4762 syntax of a command specification is given by:
4764 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
4767 @var{FLAGS} is optional and specifies the type of events relating to
4768 the time interval which enable sending the specified command, and must
4769 be a non-null sequence of identifier flags separated by "+" or "|" and
4770 enclosed between "[" and "]".
4772 The following flags are recognized:
4775 The command is sent when the current frame timestamp enters the
4776 specified interval. In other words, the command is sent when the
4777 previous frame timestamp was not in the given interval, and the
4781 The command is sent when the current frame timestamp leaves the
4782 specified interval. In other words, the command is sent when the
4783 previous frame timestamp was in the given interval, and the
4787 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
4790 @var{TARGET} specifies the target of the command, usually the name of
4791 the filter class or a specific filter instance name.
4793 @var{COMMAND} specifies the name of the command for the target filter.
4795 @var{ARG} is optional and specifies the optional list of argument for
4796 the given @var{COMMAND}.
4798 Between one interval specification and another, whitespaces, or
4799 sequences of characters starting with @code{#} until the end of line,
4800 are ignored and can be used to annotate comments.
4802 A simplified BNF description of the commands specification syntax
4805 @var{COMMAND_FLAG} ::= "enter" | "leave"
4806 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
4807 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
4808 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
4809 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
4810 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
4813 @subsection Examples
4817 Specify audio tempo change at second 4:
4819 asendcmd=c='4.0 atempo tempo 1.5',atempo
4823 Specify a list of drawtext and hue commands in a file.
4825 # show text in the interval 5-10
4826 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
4827 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
4829 # desaturate the image in the interval 15-20
4830 15.0-20.0 [enter] hue reinit s=0,
4831 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
4832 [leave] hue reinit s=1,
4833 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
4835 # apply an exponential saturation fade-out effect, starting from time 25
4836 25 [enter] hue s=exp(t-25)
4839 A filtergraph allowing to read and process the above command list
4840 stored in a file @file{test.cmd}, can be specified with:
4842 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
4846 @section asetpts, setpts
4848 Change the PTS (presentation timestamp) of the input frames.
4850 @code{asetpts} works on audio frames, @code{setpts} on video frames.
4852 Accept in input an expression evaluated through the eval API, which
4853 can contain the following constants:
4857 frame rate, only defined for constant frame-rate video
4860 the presentation timestamp in input
4863 the count of the input frame, starting from 0.
4865 @item NB_CONSUMED_SAMPLES
4866 the number of consumed samples, not including the current frame (only
4870 the number of samples in the current frame (only audio)
4876 the PTS of the first frame
4879 the time in seconds of the first frame
4882 tell if the current frame is interlaced
4885 the time in seconds of the current frame
4891 original position in the file of the frame, or undefined if undefined
4892 for the current frame
4898 previous input time in seconds
4904 previous output time in seconds
4907 @subsection Examples
4911 Start counting PTS from zero
4917 Apply fast motion effect:
4923 Apply slow motion effect:
4929 Set fixed rate of 25 frames per second:
4935 Set fixed rate 25 fps with some jitter:
4937 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
4941 Apply an offset of 10 seconds to the input PTS:
4949 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
4950 it unchanged. By default, it logs a message at a frequency of 10Hz with the
4951 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
4952 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
4954 The filter also has a video output (see the @var{video} option) with a real
4955 time graph to observe the loudness evolution. The graphic contains the logged
4956 message mentioned above, so it is not printed anymore when this option is set,
4957 unless the verbose logging is set. The main graphing area contains the
4958 short-term loudness (3 seconds of analysis), and the gauge on the right is for
4959 the momentary loudness (400 milliseconds).
4961 More information about the Loudness Recommendation EBU R128 on
4962 @url{http://tech.ebu.ch/loudness}.
4964 The filter accepts the following named parameters:
4969 Activate the video output. The audio stream is passed unchanged whether this
4970 option is set or no. The video stream will be the first output stream if
4971 activated. Default is @code{0}.
4974 Set the video size. This option is for video only. Default and minimum
4975 resolution is @code{640x480}.
4978 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
4979 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
4980 other integer value between this range is allowed.
4984 Example of real-time graph using @command{ffplay}, with a EBU scale meter +18:
4986 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
4989 Run an analysis with @command{ffmpeg}:
4991 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
4994 @section settb, asettb
4996 Set the timebase to use for the output frames timestamps.
4997 It is mainly useful for testing timebase configuration.
4999 It accepts in input an arithmetic expression representing a rational.
5000 The expression can contain the constants "AVTB" (the
5001 default timebase), "intb" (the input timebase) and "sr" (the sample rate,
5004 The default value for the input is "intb".
5006 @subsection Examples
5010 Set the timebase to 1/25:
5016 Set the timebase to 1/10:
5022 Set the timebase to 1001/1000:
5028 Set the timebase to 2*intb:
5034 Set the default timebase value:
5042 Concatenate audio and video streams, joining them together one after the
5045 The filter works on segments of synchronized video and audio streams. All
5046 segments must have the same number of streams of each type, and that will
5047 also be the number of streams at output.
5049 The filter accepts the following named parameters:
5053 Set the number of segments. Default is 2.
5056 Set the number of output video streams, that is also the number of video
5057 streams in each segment. Default is 1.
5060 Set the number of output audio streams, that is also the number of video
5061 streams in each segment. Default is 0.
5064 Activate unsafe mode: do not fail if segments have a different format.
5068 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
5069 @var{a} audio outputs.
5071 There are @var{n}×(@var{v}+@var{a}) inputs: first the inputs for the first
5072 segment, in the same order as the outputs, then the inputs for the second
5075 Related streams do not always have exactly the same duration, for various
5076 reasons including codec frame size or sloppy authoring. For that reason,
5077 related synchronized streams (e.g. a video and its audio track) should be
5078 concatenated at once. The concat filter will use the duration of the longest
5079 stream in each segment (except the last one), and if necessary pad shorter
5080 audio streams with silence.
5082 For this filter to work correctly, all segments must start at timestamp 0.
5084 All corresponding streams must have the same parameters in all segments; the
5085 filtering system will automatically select a common pixel format for video
5086 streams, and a common sample format, sample rate and channel layout for
5087 audio streams, but other settings, such as resolution, must be converted
5088 explicitly by the user.
5090 Different frame rates are acceptable but will result in variable frame rate
5091 at output; be sure to configure the output file to handle it.
5096 Concatenate an opening, an episode and an ending, all in bilingual version
5097 (video in stream 0, audio in streams 1 and 2):
5099 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
5100 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
5101 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
5102 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
5106 Concatenate two parts, handling audio and video separately, using the
5107 (a)movie sources, and adjusting the resolution:
5109 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
5110 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
5111 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
5113 Note that a desync will happen at the stitch if the audio and video streams
5114 do not have exactly the same duration in the first file.
5118 @section showspectrum
5120 Convert input audio to a video output, representing the audio frequency
5123 The filter accepts the following named parameters:
5126 Specify the video size for the output. Default value is @code{640x480}.
5128 Specify if the spectrum should slide along the window. Default value is
5132 The usage is very similar to the showwaves filter; see the examples in that
5137 Convert input audio to a video output, representing the samples waves.
5139 The filter accepts the following named parameters:
5143 Set the number of samples which are printed on the same column. A
5144 larger value will decrease the frame rate. Must be a positive
5145 integer. This option can be set only if the value for @var{rate}
5146 is not explicitly specified.
5149 Set the (approximate) output frame rate. This is done by setting the
5150 option @var{n}. Default value is "25".
5153 Specify the video size for the output. Default value is "600x240".
5156 Some examples follow.
5159 Output the input file audio and the corresponding video representation
5162 amovie=a.mp3,asplit[out0],showwaves[out1]
5166 Create a synthetic signal and show it with showwaves, forcing a
5167 framerate of 30 frames per second:
5169 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
5173 @c man end MULTIMEDIA FILTERS
5175 @chapter Multimedia Sources
5176 @c man begin MULTIMEDIA SOURCES
5178 Below is a description of the currently available multimedia sources.
5182 This is the same as @ref{src_movie} source, except it selects an audio
5188 Read audio and/or video stream(s) from a movie container.
5190 It accepts the syntax: @var{movie_name}[:@var{options}] where
5191 @var{movie_name} is the name of the resource to read (not necessarily
5192 a file but also a device or a stream accessed through some protocol),
5193 and @var{options} is an optional sequence of @var{key}=@var{value}
5194 pairs, separated by ":".
5196 The description of the accepted options follows.
5200 @item format_name, f
5201 Specifies the format assumed for the movie to read, and can be either
5202 the name of a container or an input device. If not specified the
5203 format is guessed from @var{movie_name} or by probing.
5205 @item seek_point, sp
5206 Specifies the seek point in seconds, the frames will be output
5207 starting from this seek point, the parameter is evaluated with
5208 @code{av_strtod} so the numerical value may be suffixed by an IS
5209 postfix. Default value is "0".
5212 Specifies the streams to read. Several streams can be specified, separated
5213 by "+". The source will then have as many outputs, in the same order. The
5214 syntax is explained in the @ref{Stream specifiers} chapter. Two special
5215 names, "dv" and "da" specify respectively the default (best suited) video
5216 and audio stream. Default is "dv", or "da" if the filter is called as
5219 @item stream_index, si
5220 Specifies the index of the video stream to read. If the value is -1,
5221 the best suited video stream will be automatically selected. Default
5222 value is "-1". Deprecated. If the filter is called "amovie", it will select
5223 audio instead of video.
5226 Specifies how many times to read the stream in sequence.
5227 If the value is less than 1, the stream will be read again and again.
5228 Default value is "1".
5230 Note that when the movie is looped the source timestamps are not
5231 changed, so it will generate non monotonically increasing timestamps.
5234 This filter allows to overlay a second video on top of main input of
5235 a filtergraph as shown in this graph:
5237 input -----------> deltapts0 --> overlay --> output
5240 movie --> scale--> deltapts1 -------+
5243 Some examples follow.
5247 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
5248 on top of the input labelled as "in":
5250 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
5251 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
5255 Read from a video4linux2 device, and overlay it on top of the input
5258 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
5259 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
5263 Read the first video stream and the audio stream with id 0x81 from
5264 dvd.vob; the video is connected to the pad named "video" and the audio is
5265 connected to the pad named "audio":
5267 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
5271 @c man end MULTIMEDIA SOURCES