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 parameters. If none are specified
415 then the filter will automatically convert between its input
418 This filter is also able to stretch/squeeze the audio data to make it match
419 the timestamps or to inject silence / cut out audio to make it match the
420 timestamps, do a combination of both or do neither.
422 The filter accepts the following named parameters:
426 Minimum difference between timestamps and audio data (in seconds) to trigger
427 stretching/squeezing/filling or trimming of the data to make it match the
428 timestamps. The default is that stretching/squeezing/filling and
429 trimming is disabled (min_comp = infinite).
432 Minimum difference between timestamps and audio data (in seconds) to trigger
433 adding/dropping samples to make it match the timestamps.
434 This option effectively is a threshold to select between hard (trim/fill) and
435 soft (squeeze/stretch) compensation. Note that all compensation is by default
436 disabled through min_comp.
437 The default is 0.1 seconds.
440 Maximum stretch/squeeze factor.
443 @item tsf, internal_sample_fmt
444 Internal sampling format.
445 Default is automatic selection
447 @item clev, center_mix_level
448 center mix level, for rematrixing
451 @item slev, surround_mix_level
452 surround mix level, for rematrixing
455 @item rmvol, rematrix_volume
460 Low frequency effects mix level.
463 @item matrix_encoding
464 matrixed stereo encoding
467 No matrixed stereo encoding
470 Dolby matrixed stereo encoding
473 Dolby Pro Logic II matrixed stereo encoding
476 Default value is @code{none}.
480 For example, to resample the input audio to 44100Hz:
485 @section asetnsamples
487 Set the number of samples per each output audio frame.
489 The last output packet may contain a different number of samples, as
490 the filter will flush all the remaining samples when the input audio
493 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
498 @item nb_out_samples, n
499 Set the number of frames per each output audio frame. The number is
500 intended as the number of samples @emph{per each channel}.
501 Default value is 1024.
504 If set to 1, the filter will pad the last audio frame with zeroes, so
505 that the last frame will contain the same number of samples as the
506 previous ones. Default value is 1.
509 For example, to set the number of per-frame samples to 1234 and
510 disable padding for the last frame, use:
512 asetnsamples=n=1234:p=0
517 Show a line containing various information for each input audio frame.
518 The input audio is not modified.
520 The shown line contains a sequence of key/value pairs of the form
521 @var{key}:@var{value}.
523 A description of each shown parameter follows:
527 sequential number of the input frame, starting from 0
530 Presentation timestamp of the input frame, in time base units; the time base
531 depends on the filter input pad, and is usually 1/@var{sample_rate}.
534 presentation timestamp of the input frame in seconds
537 position of the frame in the input stream, -1 if this information in
538 unavailable and/or meaningless (for example in case of synthetic audio)
547 sample rate for the audio frame
550 number of samples (per channel) in the frame
553 Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
554 the data is treated as if all the planes were concatenated.
556 @item plane_checksums
557 A list of Adler-32 checksums for each data plane.
562 Split input audio into several identical outputs.
564 The filter accepts a single parameter which specifies the number of outputs. If
565 unspecified, it defaults to 2.
569 [in] asplit [out0][out1]
572 will create two separate outputs from the same input.
574 To create 3 or more outputs, you need to specify the number of
577 [in] asplit=3 [out0][out1][out2]
581 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
583 will create 5 copies of the input audio.
588 Forward two audio streams and control the order the buffers are forwarded.
590 The argument to the filter is an expression deciding which stream should be
591 forwarded next: if the result is negative, the first stream is forwarded; if
592 the result is positive or zero, the second stream is forwarded. It can use
593 the following variables:
597 number of buffers forwarded so far on each stream
599 number of samples forwarded so far on each stream
601 current timestamp of each stream
604 The default value is @code{t1-t2}, which means to always forward the stream
605 that has a smaller timestamp.
607 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
608 input, while avoiding too much of a desynchronization:
610 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
611 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
619 The filter accepts exactly one parameter, the audio tempo. If not
620 specified then the filter will assume nominal 1.0 tempo. Tempo must
621 be in the [0.5, 2.0] range.
623 For example, to slow down audio to 80% tempo:
628 For example, to speed up audio to 125% tempo:
635 Make audio easier to listen to on headphones.
637 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
638 so that when listened to on headphones the stereo image is moved from
639 inside your head (standard for headphones) to outside and in front of
640 the listener (standard for speakers).
646 Mix channels with specific gain levels. The filter accepts the output
647 channel layout followed by a set of channels definitions.
649 This filter is also designed to remap efficiently the channels of an audio
652 The filter accepts parameters of the form:
653 "@var{l}:@var{outdef}:@var{outdef}:..."
657 output channel layout or number of channels
660 output channel specification, of the form:
661 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
664 output channel to define, either a channel name (FL, FR, etc.) or a channel
665 number (c0, c1, etc.)
668 multiplicative coefficient for the channel, 1 leaving the volume unchanged
671 input channel to use, see out_name for details; it is not possible to mix
672 named and numbered input channels
675 If the `=' in a channel specification is replaced by `<', then the gains for
676 that specification will be renormalized so that the total is 1, thus
677 avoiding clipping noise.
679 @subsection Mixing examples
681 For example, if you want to down-mix from stereo to mono, but with a bigger
682 factor for the left channel:
684 pan=1:c0=0.9*c0+0.1*c1
687 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
690 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
693 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
694 that should be preferred (see "-ac" option) unless you have very specific
697 @subsection Remapping examples
699 The channel remapping will be effective if, and only if:
702 @item gain coefficients are zeroes or ones,
703 @item only one input per channel output,
706 If all these conditions are satisfied, the filter will notify the user ("Pure
707 channel mapping detected"), and use an optimized and lossless method to do the
710 For example, if you have a 5.1 source and want a stereo audio stream by
711 dropping the extra channels:
713 pan="stereo: c0=FL : c1=FR"
716 Given the same source, you can also switch front left and front right channels
717 and keep the input channel layout:
719 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
722 If the input is a stereo audio stream, you can mute the front left channel (and
723 still keep the stereo channel layout) with:
728 Still with a stereo audio stream input, you can copy the right channel in both
729 front left and right:
731 pan="stereo: c0=FR : c1=FR"
734 @section silencedetect
736 Detect silence in an audio stream.
738 This filter logs a message when it detects that the input audio volume is less
739 or equal to a noise tolerance value for a duration greater or equal to the
740 minimum detected noise duration.
742 The printed times and duration are expressed in seconds.
746 Set silence duration until notification (default is 2 seconds).
749 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
750 specified value) or amplitude ratio. Default is -60dB, or 0.001.
753 Detect 5 seconds of silence with -50dB noise tolerance:
755 silencedetect=n=-50dB:d=5
758 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
759 tolerance in @file{silence.mp3}:
761 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
765 Synchronize audio data with timestamps by squeezing/stretching it and/or
766 dropping samples/adding silence when needed.
768 The filter accepts the following named parameters:
772 Enable stretching/squeezing the data to make it match the timestamps. Disabled
773 by default. When disabled, time gaps are covered with silence.
776 Minimum difference between timestamps and audio data (in seconds) to trigger
777 adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
778 this filter, try setting this parameter to 0.
781 Maximum compensation in samples per second. Relevant only with compensate=1.
785 Assume the first pts should be this value.
786 This allows for padding/trimming at the start of stream. By default, no
787 assumption is made about the first frame's expected pts, so no padding or
788 trimming is done. For example, this could be set to 0 to pad the beginning with
789 silence if an audio stream starts after the video stream.
793 @section channelsplit
794 Split each channel in input audio stream into a separate output stream.
796 This filter accepts the following named parameters:
799 Channel layout of the input stream. Default is "stereo".
802 For example, assuming a stereo input MP3 file
804 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
806 will create an output Matroska file with two audio streams, one containing only
807 the left channel and the other the right channel.
809 To split a 5.1 WAV file into per-channel files
811 ffmpeg -i in.wav -filter_complex
812 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
813 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
814 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
819 Remap input channels to new locations.
821 This filter accepts the following named parameters:
824 Channel layout of the output stream.
827 Map channels from input to output. The argument is a comma-separated list of
828 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
829 @var{in_channel} form. @var{in_channel} can be either the name of the input
830 channel (e.g. FL for front left) or its index in the input channel layout.
831 @var{out_channel} is the name of the output channel or its index in the output
832 channel layout. If @var{out_channel} is not given then it is implicitly an
833 index, starting with zero and increasing by one for each mapping.
836 If no mapping is present, the filter will implicitly map input channels to
837 output channels preserving index.
839 For example, assuming a 5.1+downmix input MOV file
841 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
843 will create an output WAV file tagged as stereo from the downmix channels of
846 To fix a 5.1 WAV improperly encoded in AAC's native channel order
848 ffmpeg -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
852 Join multiple input streams into one multi-channel stream.
854 The filter accepts the following named parameters:
858 Number of input streams. Defaults to 2.
861 Desired output channel layout. Defaults to stereo.
864 Map channels from inputs to output. The argument is a comma-separated list of
865 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
866 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
867 can be either the name of the input channel (e.g. FL for front left) or its
868 index in the specified input stream. @var{out_channel} is the name of the output
872 The filter will attempt to guess the mappings when those are not specified
873 explicitly. It does so by first trying to find an unused matching input channel
874 and if that fails it picks the first unused input channel.
876 E.g. to join 3 inputs (with properly set channel layouts)
878 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
881 To build a 5.1 output from 6 single-channel streams:
883 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
884 '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'
889 Convert the audio sample format, sample rate and channel layout. This filter is
890 not meant to be used directly.
894 Adjust the input audio volume.
896 The filter accepts the following named parameters. If the key of the
897 first options is omitted, the arguments are interpreted according to
898 the following syntax:
900 volume=@var{volume}:@var{precision}
906 Expresses how the audio volume will be increased or decreased.
908 Output values are clipped to the maximum value.
910 The output audio volume is given by the relation:
912 @var{output_volume} = @var{volume} * @var{input_volume}
915 Default value for @var{volume} is 1.0.
918 Set the mathematical precision.
920 This determines which input sample formats will be allowed, which affects the
921 precision of the volume scaling.
925 8-bit fixed-point; limits input sample format to U8, S16, and S32.
927 32-bit floating-point; limits input sample format to FLT. (default)
929 64-bit floating-point; limits input sample format to DBL.
937 Halve the input audio volume:
941 volume=volume=-6.0206dB
944 In all the above example the named key for @option{volume} can be
945 omitted, for example like in:
951 Increase input audio power by 6 decibels using fixed-point precision:
953 volume=volume=6dB:precision=fixed
957 @section volumedetect
959 Detect the volume of the input video.
961 The filter has no parameters. The input is not modified. Statistics about
962 the volume will be printed in the log when the input stream end is reached.
964 In particular it will show the mean volume (root mean square), maximum
965 volume (on a per-sample basis), and the beginning of an histogram of the
966 registered volume values (from the maximum value to a cumulated 1/1000 of
969 All volumes are in decibels relative to the maximum PCM value.
971 Here is an excerpt of the output:
973 [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB
974 [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB
975 [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6
976 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62
977 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286
978 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042
979 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551
980 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609
981 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409
987 The mean square energy is approximately -27 dB, or 10^-2.7.
989 The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
991 There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
994 In other words, raising the volume by +4 dB does not cause any clipping,
995 raising it by +5 dB causes clipping for 6 samples, etc.
997 @c man end AUDIO FILTERS
999 @chapter Audio Sources
1000 @c man begin AUDIO SOURCES
1002 Below is a description of the currently available audio sources.
1006 Buffer audio frames, and make them available to the filter chain.
1008 This source is mainly intended for a programmatic use, in particular
1009 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
1011 It accepts the following mandatory parameters:
1012 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
1017 The sample rate of the incoming audio buffers.
1020 The sample format of the incoming audio buffers.
1021 Either a sample format name or its corresponging integer representation from
1022 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
1024 @item channel_layout
1025 The channel layout of the incoming audio buffers.
1026 Either a channel layout name from channel_layout_map in
1027 @file{libavutil/channel_layout.c} or its corresponding integer representation
1028 from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h}
1034 abuffer=44100:s16p:stereo
1037 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
1038 Since the sample format with name "s16p" corresponds to the number
1039 6 and the "stereo" channel layout corresponds to the value 0x3, this is
1047 Generate an audio signal specified by an expression.
1049 This source accepts in input one or more expressions (one for each
1050 channel), which are evaluated and used to generate a corresponding
1053 It accepts the syntax: @var{exprs}[::@var{options}].
1054 @var{exprs} is a list of expressions separated by ":", one for each
1055 separate channel. In case the @var{channel_layout} is not
1056 specified, the selected channel layout depends on the number of
1057 provided expressions.
1059 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1062 The description of the accepted options follows.
1066 @item channel_layout, c
1067 Set the channel layout. The number of channels in the specified layout
1068 must be equal to the number of specified expressions.
1071 Set the minimum duration of the sourced audio. See the function
1072 @code{av_parse_time()} for the accepted format.
1073 Note that the resulting duration may be greater than the specified
1074 duration, as the generated audio is always cut at the end of a
1077 If not specified, or the expressed duration is negative, the audio is
1078 supposed to be generated forever.
1081 Set the number of samples per channel per each output frame,
1084 @item sample_rate, s
1085 Specify the sample rate, default to 44100.
1088 Each expression in @var{exprs} can contain the following constants:
1092 number of the evaluated sample, starting from 0
1095 time of the evaluated sample expressed in seconds, starting from 0
1102 @subsection Examples
1114 Generate a sin signal with frequency of 440 Hz, set sample rate to
1117 aevalsrc="sin(440*2*PI*t)::s=8000"
1121 Generate a two channels signal, specify the channel layout (Front
1122 Center + Back Center) explicitly:
1124 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
1128 Generate white noise:
1130 aevalsrc="-2+random(0)"
1134 Generate an amplitude modulated signal:
1136 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
1140 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
1142 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
1149 Null audio source, return unprocessed audio frames. It is mainly useful
1150 as a template and to be employed in analysis / debugging tools, or as
1151 the source for filters which ignore the input data (for example the sox
1154 It accepts an optional sequence of @var{key}=@var{value} pairs,
1157 The description of the accepted options follows.
1161 @item sample_rate, s
1162 Specify the sample rate, and defaults to 44100.
1164 @item channel_layout, cl
1166 Specify the channel layout, and can be either an integer or a string
1167 representing a channel layout. The default value of @var{channel_layout}
1170 Check the channel_layout_map definition in
1171 @file{libavutil/channel_layout.c} for the mapping between strings and
1172 channel layout values.
1175 Set the number of samples per requested frames.
1179 Follow some examples:
1181 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1182 anullsrc=r=48000:cl=4
1185 anullsrc=r=48000:cl=mono
1189 Buffer audio frames, and make them available to the filter chain.
1191 This source is not intended to be part of user-supplied graph descriptions but
1192 for insertion by calling programs through the interface defined in
1193 @file{libavfilter/buffersrc.h}.
1195 It accepts the following named parameters:
1199 Timebase which will be used for timestamps of submitted frames. It must be
1200 either a floating-point number or in @var{numerator}/@var{denominator} form.
1206 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1208 @item channel_layout
1209 Channel layout of the audio data, in the form that can be accepted by
1210 @code{av_get_channel_layout()}.
1213 All the parameters need to be explicitly defined.
1217 Synthesize a voice utterance using the libflite library.
1219 To enable compilation of this filter you need to configure FFmpeg with
1220 @code{--enable-libflite}.
1222 Note that the flite library is not thread-safe.
1224 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1227 The description of the accepted parameters follows.
1232 If set to 1, list the names of the available voices and exit
1233 immediately. Default value is 0.
1236 Set the maximum number of samples per frame. Default value is 512.
1239 Set the filename containing the text to speak.
1242 Set the text to speak.
1245 Set the voice to use for the speech synthesis. Default value is
1246 @code{kal}. See also the @var{list_voices} option.
1249 @subsection Examples
1253 Read from file @file{speech.txt}, and synthetize the text using the
1254 standard flite voice:
1256 flite=textfile=speech.txt
1260 Read the specified text selecting the @code{slt} voice:
1262 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1266 Input text to ffmpeg:
1268 ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1272 Make @file{ffplay} speak the specified text, using @code{flite} and
1273 the @code{lavfi} device:
1275 ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
1279 For more information about libflite, check:
1280 @url{http://www.speech.cs.cmu.edu/flite/}
1282 @c man end AUDIO SOURCES
1284 @chapter Audio Sinks
1285 @c man begin AUDIO SINKS
1287 Below is a description of the currently available audio sinks.
1289 @section abuffersink
1291 Buffer audio frames, and make them available to the end of filter chain.
1293 This sink is mainly intended for programmatic use, in particular
1294 through the interface defined in @file{libavfilter/buffersink.h}.
1296 It requires a pointer to an AVABufferSinkContext structure, which
1297 defines the incoming buffers' formats, to be passed as the opaque
1298 parameter to @code{avfilter_init_filter} for initialization.
1302 Null audio sink, do absolutely nothing with the input audio. It is
1303 mainly useful as a template and to be employed in analysis / debugging
1306 @section abuffersink
1307 This sink is intended for programmatic use. Frames that arrive on this sink can
1308 be retrieved by the calling program using the interface defined in
1309 @file{libavfilter/buffersink.h}.
1311 This filter accepts no parameters.
1313 @c man end AUDIO SINKS
1315 @chapter Video Filters
1316 @c man begin VIDEO FILTERS
1318 When you configure your FFmpeg build, you can disable any of the
1319 existing filters using @code{--disable-filters}.
1320 The configure output will show the video filters included in your
1323 Below is a description of the currently available video filters.
1325 @section alphaextract
1327 Extract the alpha component from the input as a grayscale video. This
1328 is especially useful with the @var{alphamerge} filter.
1332 Add or replace the alpha component of the primary input with the
1333 grayscale value of a second input. This is intended for use with
1334 @var{alphaextract} to allow the transmission or storage of frame
1335 sequences that have alpha in a format that doesn't support an alpha
1338 For example, to reconstruct full frames from a normal YUV-encoded video
1339 and a separate video created with @var{alphaextract}, you might use:
1341 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1344 Since this filter is designed for reconstruction, it operates on frame
1345 sequences without considering timestamps, and terminates when either
1346 input reaches end of stream. This will cause problems if your encoding
1347 pipeline drops frames. If you're trying to apply an image as an
1348 overlay to a video stream, consider the @var{overlay} filter instead.
1352 Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
1353 and libavformat to work. On the other hand, it is limited to ASS (Advanced
1354 Substation Alpha) subtitles files.
1358 Compute the bounding box for the non-black pixels in the input frame
1361 This filter computes the bounding box containing all the pixels with a
1362 luminance value greater than the minimum allowed value.
1363 The parameters describing the bounding box are printed on the filter
1366 @section blackdetect
1368 Detect video intervals that are (almost) completely black. Can be
1369 useful to detect chapter transitions, commercials, or invalid
1370 recordings. Output lines contains the time for the start, end and
1371 duration of the detected black interval expressed in seconds.
1373 In order to display the output lines, you need to set the loglevel at
1374 least to the AV_LOG_INFO value.
1376 This filter accepts a list of options in the form of
1377 @var{key}=@var{value} pairs separated by ":". A description of the
1378 accepted options follows.
1381 @item black_min_duration, d
1382 Set the minimum detected black duration expressed in seconds. It must
1383 be a non-negative floating point number.
1385 Default value is 2.0.
1387 @item picture_black_ratio_th, pic_th
1388 Set the threshold for considering a picture "black".
1389 Express the minimum value for the ratio:
1391 @var{nb_black_pixels} / @var{nb_pixels}
1394 for which a picture is considered black.
1395 Default value is 0.98.
1397 @item pixel_black_th, pix_th
1398 Set the threshold for considering a pixel "black".
1400 The threshold expresses the maximum pixel luminance value for which a
1401 pixel is considered "black". The provided value is scaled according to
1402 the following equation:
1404 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1407 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1408 the input video format, the range is [0-255] for YUV full-range
1409 formats and [16-235] for YUV non full-range formats.
1411 Default value is 0.10.
1414 The following example sets the maximum pixel threshold to the minimum
1415 value, and detects only black intervals of 2 or more seconds:
1417 blackdetect=d=2:pix_th=0.00
1422 Detect frames that are (almost) completely black. Can be useful to
1423 detect chapter transitions or commercials. Output lines consist of
1424 the frame number of the detected frame, the percentage of blackness,
1425 the position in the file if known or -1 and the timestamp in seconds.
1427 In order to display the output lines, you need to set the loglevel at
1428 least to the AV_LOG_INFO value.
1430 The filter accepts the syntax:
1432 blackframe[=@var{amount}:[@var{threshold}]]
1435 @var{amount} is the percentage of the pixels that have to be below the
1436 threshold, and defaults to 98.
1438 @var{threshold} is the threshold below which a pixel value is
1439 considered black, and defaults to 32.
1443 Apply boxblur algorithm to the input video.
1445 This filter accepts the parameters:
1446 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
1448 Chroma and alpha parameters are optional, if not specified they default
1449 to the corresponding values set for @var{luma_radius} and
1452 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
1453 the radius in pixels of the box used for blurring the corresponding
1454 input plane. They are expressions, and can contain the following
1458 the input width and height in pixels
1461 the input chroma image width and height in pixels
1464 horizontal and vertical chroma subsample values. For example for the
1465 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1468 The radius must be a non-negative number, and must not be greater than
1469 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
1470 and of @code{min(cw,ch)/2} for the chroma planes.
1472 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
1473 how many times the boxblur filter is applied to the corresponding
1476 Some examples follow:
1481 Apply a boxblur filter with luma, chroma, and alpha radius
1488 Set luma radius to 2, alpha and chroma radius to 0
1494 Set luma and chroma radius to a fraction of the video dimension
1496 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
1501 @section colormatrix
1503 The colormatrix filter allows conversion between any of the following color
1504 space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m})
1505 and FCC (@var{fcc}).
1507 The syntax of the parameters is @var{source}:@var{destination}:
1510 colormatrix=bt601:smpte240m
1515 Copy the input source unchanged to the output. Mainly useful for
1520 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}
1522 The @var{keep_aspect} parameter is optional, if specified and set to a
1523 non-zero value will force the output display aspect ratio to be the
1524 same of the input, by changing the output sample aspect ratio.
1526 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
1527 expressions containing the following constants:
1531 the computed values for @var{x} and @var{y}. They are evaluated for
1535 the input width and height
1538 same as @var{in_w} and @var{in_h}
1541 the output (cropped) width and height
1544 same as @var{out_w} and @var{out_h}
1547 same as @var{iw} / @var{ih}
1550 input sample aspect ratio
1553 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1556 horizontal and vertical chroma subsample values. For example for the
1557 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1560 the number of input frame, starting from 0
1563 the position in the file of the input frame, NAN if unknown
1566 timestamp expressed in seconds, NAN if the input timestamp is unknown
1570 The @var{out_w} and @var{out_h} parameters specify the expressions for
1571 the width and height of the output (cropped) video. They are
1572 evaluated just at the configuration of the filter.
1574 The default value of @var{out_w} is "in_w", and the default value of
1575 @var{out_h} is "in_h".
1577 The expression for @var{out_w} may depend on the value of @var{out_h},
1578 and the expression for @var{out_h} may depend on @var{out_w}, but they
1579 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
1580 evaluated after @var{out_w} and @var{out_h}.
1582 The @var{x} and @var{y} parameters specify the expressions for the
1583 position of the top-left corner of the output (non-cropped) area. They
1584 are evaluated for each frame. If the evaluated value is not valid, it
1585 is approximated to the nearest valid value.
1587 The default value of @var{x} is "(in_w-out_w)/2", and the default
1588 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
1589 the center of the input image.
1591 The expression for @var{x} may depend on @var{y}, and the expression
1592 for @var{y} may depend on @var{x}.
1594 Follow some examples:
1596 # crop the central input area with size 100x100
1599 # crop the central input area with size 2/3 of the input video
1600 "crop=2/3*in_w:2/3*in_h"
1602 # crop the input video central square
1605 # delimit the rectangle with the top-left corner placed at position
1606 # 100:100 and the right-bottom corner corresponding to the right-bottom
1607 # corner of the input image.
1608 crop=in_w-100:in_h-100:100:100
1610 # crop 10 pixels from the left and right borders, and 20 pixels from
1611 # the top and bottom borders
1612 "crop=in_w-2*10:in_h-2*20"
1614 # keep only the bottom right quarter of the input image
1615 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
1617 # crop height for getting Greek harmony
1618 "crop=in_w:1/PHI*in_w"
1621 "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)"
1623 # erratic camera effect depending on timestamp
1624 "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)"
1626 # set x depending on the value of y
1627 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
1632 Auto-detect crop size.
1634 Calculate necessary cropping parameters and prints the recommended
1635 parameters through the logging system. The detected dimensions
1636 correspond to the non-black area of the input video.
1638 It accepts the syntax:
1640 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
1646 Threshold, which can be optionally specified from nothing (0) to
1647 everything (255), defaults to 24.
1650 Value which the width/height should be divisible by, defaults to
1651 16. The offset is automatically adjusted to center the video. Use 2 to
1652 get only even dimensions (needed for 4:2:2 video). 16 is best when
1653 encoding to most video codecs.
1656 Counter that determines after how many frames cropdetect will reset
1657 the previously detected largest video area and start over to detect
1658 the current optimal crop area. Defaults to 0.
1660 This can be useful when channel logos distort the video area. 0
1661 indicates never reset and return the largest area encountered during
1667 This filter drops frames that do not differ greatly from the previous
1668 frame in order to reduce framerate. The main use of this filter is
1669 for very-low-bitrate encoding (e.g. streaming over dialup modem), but
1670 it could in theory be used for fixing movies that were
1671 inverse-telecined incorrectly.
1673 It accepts the following parameters:
1674 @var{max}:@var{hi}:@var{lo}:@var{frac}.
1679 Set the maximum number of consecutive frames which can be dropped (if
1680 positive), or the minimum interval between dropped frames (if
1681 negative). If the value is 0, the frame is dropped unregarding the
1682 number of previous sequentially dropped frames.
1687 Set the dropping threshold values.
1689 Values for @var{hi} and @var{lo} are for 8x8 pixel blocks and
1690 represent actual pixel value differences, so a threshold of 64
1691 corresponds to 1 unit of difference for each pixel, or the same spread
1692 out differently over the block.
1694 A frame is a candidate for dropping if no 8x8 blocks differ by more
1695 than a threshold of @var{hi}, and if no more than @var{frac} blocks (1
1696 meaning the whole image) differ by more than a threshold of @var{lo}.
1698 Default value for @var{hi} is 64*12, default value for @var{lo} is
1699 64*5, and default value for @var{frac} is 0.33.
1704 Suppress a TV station logo by a simple interpolation of the surrounding
1705 pixels. Just set a rectangle covering the logo and watch it disappear
1706 (and sometimes something even uglier appear - your mileage may vary).
1708 The filter accepts parameters as a string of the form
1709 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
1710 @var{key}=@var{value} pairs, separated by ":".
1712 The description of the accepted parameters follows.
1717 Specify the top left corner coordinates of the logo. They must be
1721 Specify the width and height of the logo to clear. They must be
1725 Specify the thickness of the fuzzy edge of the rectangle (added to
1726 @var{w} and @var{h}). The default value is 4.
1729 When set to 1, a green rectangle is drawn on the screen to simplify
1730 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1731 @var{band} is set to 4. The default value is 0.
1735 Some examples follow.
1740 Set a rectangle covering the area with top left corner coordinates 0,0
1741 and size 100x77, setting a band of size 10:
1743 delogo=0:0:100:77:10
1747 As the previous example, but use named options:
1749 delogo=x=0:y=0:w=100:h=77:band=10
1756 Attempt to fix small changes in horizontal and/or vertical shift. This
1757 filter helps remove camera shake from hand-holding a camera, bumping a
1758 tripod, moving on a vehicle, etc.
1760 The filter accepts parameters as a string of the form
1761 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
1763 A description of the accepted parameters follows.
1768 Specify a rectangular area where to limit the search for motion
1770 If desired the search for motion vectors can be limited to a
1771 rectangular area of the frame defined by its top left corner, width
1772 and height. These parameters have the same meaning as the drawbox
1773 filter which can be used to visualise the position of the bounding
1776 This is useful when simultaneous movement of subjects within the frame
1777 might be confused for camera motion by the motion vector search.
1779 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
1780 then the full frame is used. This allows later options to be set
1781 without specifying the bounding box for the motion vector search.
1783 Default - search the whole frame.
1786 Specify the maximum extent of movement in x and y directions in the
1787 range 0-64 pixels. Default 16.
1790 Specify how to generate pixels to fill blanks at the edge of the
1791 frame. An integer from 0 to 3 as follows:
1794 Fill zeroes at blank locations
1796 Original image at blank locations
1798 Extruded edge value at blank locations
1800 Mirrored edge at blank locations
1803 The default setting is mirror edge at blank locations.
1806 Specify the blocksize to use for motion search. Range 4-128 pixels,
1810 Specify the contrast threshold for blocks. Only blocks with more than
1811 the specified contrast (difference between darkest and lightest
1812 pixels) will be considered. Range 1-255, default 125.
1815 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
1816 search. Default - exhaustive search.
1819 If set then a detailed log of the motion search is written to the
1826 Draw a colored box on the input image.
1828 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1831 The description of the accepted parameters follows.
1835 Specify the top left corner coordinates of the box. Default to 0.
1839 Specify the width and height of the box, if 0 they are interpreted as
1840 the input width and height. Default to 0.
1843 Specify the color of the box to write, it can be the name of a color
1844 (case insensitive match) or a 0xRRGGBB[AA] sequence. If the special
1845 value @code{invert} is used, the box edge color is the same as the
1846 video with inverted luma.
1849 Set the thickness of the box edge. Default value is @code{4}.
1852 If the key of the first options is omitted, the arguments are
1853 interpreted according to the following syntax:
1855 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}:@var{thickness}
1858 Some examples follow:
1861 Draw a black box around the edge of the input image:
1867 Draw a box with color red and an opacity of 50%:
1869 drawbox=10:20:200:60:red@@0.5
1872 The previous example can be specified as:
1874 drawbox=x=10:y=20:w=200:h=60:color=red@@0.5
1878 Fill the box with pink color:
1880 drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max
1887 Draw text string or text from specified file on top of video using the
1888 libfreetype library.
1890 To enable compilation of this filter you need to configure FFmpeg with
1891 @code{--enable-libfreetype}.
1895 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1898 The description of the accepted parameters follows.
1903 Used to draw a box around text using background color.
1904 Value should be either 1 (enable) or 0 (disable).
1905 The default value of @var{box} is 0.
1908 The color to be used for drawing box around text.
1909 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1910 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1911 The default value of @var{boxcolor} is "white".
1914 Set an expression which specifies if the text should be drawn. If the
1915 expression evaluates to 0, the text is not drawn. This is useful for
1916 specifying that the text should be drawn only when specific conditions
1919 Default value is "1".
1921 See below for the list of accepted constants and functions.
1924 Select how the @var{text} is expanded. Can be either @code{none},
1925 @code{strftime} (default for compatibity reasons but deprecated) or
1926 @code{normal}. See the @ref{drawtext_expansion, Text expansion} section
1930 If true, check and fix text coords to avoid clipping.
1933 The color to be used for drawing fonts.
1934 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1935 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1936 The default value of @var{fontcolor} is "black".
1939 The font file to be used for drawing text. Path must be included.
1940 This parameter is mandatory.
1943 The font size to be used for drawing text.
1944 The default value of @var{fontsize} is 16.
1947 Flags to be used for loading the fonts.
1949 The flags map the corresponding flags supported by libfreetype, and are
1950 a combination of the following values:
1957 @item vertical_layout
1958 @item force_autohint
1961 @item ignore_global_advance_width
1963 @item ignore_transform
1970 Default value is "render".
1972 For more information consult the documentation for the FT_LOAD_*
1976 The color to be used for drawing a shadow behind the drawn text. It
1977 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1978 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1979 The default value of @var{shadowcolor} is "black".
1981 @item shadowx, shadowy
1982 The x and y offsets for the text shadow position with respect to the
1983 position of the text. They can be either positive or negative
1984 values. Default value for both is "0".
1987 The size in number of spaces to use for rendering the tab.
1991 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
1992 format. It can be used with or without text parameter. @var{timecode_rate}
1993 option must be specified.
1995 @item timecode_rate, rate, r
1996 Set the timecode frame rate (timecode only).
1999 The text string to be drawn. The text must be a sequence of UTF-8
2001 This parameter is mandatory if no file is specified with the parameter
2005 A text file containing text to be drawn. The text must be a sequence
2006 of UTF-8 encoded characters.
2008 This parameter is mandatory if no text string is specified with the
2009 parameter @var{text}.
2011 If both @var{text} and @var{textfile} are specified, an error is thrown.
2014 If set to 1, the @var{textfile} will be reloaded before each frame.
2015 Be sure to update it atomically, or it may be read partially, or even fail.
2018 The expressions which specify the offsets where text will be drawn
2019 within the video frame. They are relative to the top/left border of the
2022 The default value of @var{x} and @var{y} is "0".
2024 See below for the list of accepted constants and functions.
2027 The parameters for @var{x} and @var{y} are expressions containing the
2028 following constants and functions:
2032 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2035 horizontal and vertical chroma subsample values. For example for the
2036 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2039 the height of each text line
2047 @item max_glyph_a, ascent
2048 the maximum distance from the baseline to the highest/upper grid
2049 coordinate used to place a glyph outline point, for all the rendered
2051 It is a positive value, due to the grid's orientation with the Y axis
2054 @item max_glyph_d, descent
2055 the maximum distance from the baseline to the lowest grid coordinate
2056 used to place a glyph outline point, for all the rendered glyphs.
2057 This is a negative value, due to the grid's orientation, with the Y axis
2061 maximum glyph height, that is the maximum height for all the glyphs
2062 contained in the rendered text, it is equivalent to @var{ascent} -
2066 maximum glyph width, that is the maximum width for all the glyphs
2067 contained in the rendered text
2070 the number of input frame, starting from 0
2072 @item rand(min, max)
2073 return a random number included between @var{min} and @var{max}
2076 input sample aspect ratio
2079 timestamp expressed in seconds, NAN if the input timestamp is unknown
2082 the height of the rendered text
2085 the width of the rendered text
2088 the x and y offset coordinates where the text is drawn.
2090 These parameters allow the @var{x} and @var{y} expressions to refer
2091 each other, so you can for example specify @code{y=x/dar}.
2094 If libavfilter was built with @code{--enable-fontconfig}, then
2095 @option{fontfile} can be a fontconfig pattern or omitted.
2097 @anchor{drawtext_expansion}
2098 @subsection Text expansion
2100 If @option{expansion} is set to @code{strftime} (which is the default for
2101 now), the filter recognizes strftime() sequences in the provided text and
2102 expands them accordingly. Check the documentation of strftime(). This
2103 feature is deprecated.
2105 If @option{expansion} is set to @code{none}, the text is printed verbatim.
2107 If @option{expansion} is set to @code{normal} (which will be the default),
2108 the following expansion mechanism is used.
2110 The backslash character '\', followed by any character, always expands to
2111 the second character.
2113 Sequence of the form @code{%@{...@}} are expanded. The text between the
2114 braces is a function name, possibly followed by arguments separated by ':'.
2115 If the arguments contain special characters or delimiters (':' or '@}'),
2116 they should be escaped.
2118 Note that they probably must also be escaped as the value for the
2119 @option{text} option in the filter argument string and as the filter
2120 argument in the filter graph description, and possibly also for the shell,
2121 that makes up to four levels of escaping; using a text file avoids these
2124 The following functions are available:
2129 The expression evaluation result.
2131 It must take one argument specifying the expression to be evaluated,
2132 which accepts the same constants and functions as the @var{x} and
2133 @var{y} values. Note that not all constants should be used, for
2134 example the text size is not known when evaluating the expression, so
2135 the constants @var{text_w} and @var{text_h} will have an undefined
2139 The time at which the filter is running, expressed in UTC.
2140 It can accept an argument: a strftime() format string.
2143 The time at which the filter is running, expressed in the local time zone.
2144 It can accept an argument: a strftime() format string.
2147 The frame number, starting from 0.
2150 The timestamp of the current frame, in seconds, with microsecond accuracy.
2154 @subsection Examples
2156 Some examples follow.
2161 Draw "Test Text" with font FreeSerif, using the default values for the
2162 optional parameters.
2165 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
2169 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
2170 and y=50 (counting from the top-left corner of the screen), text is
2171 yellow with a red box around it. Both the text and the box have an
2175 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
2176 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
2179 Note that the double quotes are not necessary if spaces are not used
2180 within the parameter list.
2183 Show the text at the center of the video frame:
2185 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
2189 Show a text line sliding from right to left in the last row of the video
2190 frame. The file @file{LONG_LINE} is assumed to contain a single line
2193 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
2197 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
2199 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
2203 Draw a single green letter "g", at the center of the input video.
2204 The glyph baseline is placed at half screen height.
2206 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
2210 Show text for 1 second every 3 seconds:
2212 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\,3)\,1):text='blink'"
2216 Use fontconfig to set the font. Note that the colons need to be escaped.
2218 drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
2222 Print the date of a real-time encoding (see strftime(3)):
2224 drawtext='fontfile=FreeSans.ttf:expansion=normal:text=%@{localtime:%a %b %d %Y@}'
2229 For more information about libfreetype, check:
2230 @url{http://www.freetype.org/}.
2232 For more information about fontconfig, check:
2233 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
2237 Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
2239 This filter accepts the following optional named parameters:
2243 Set low and high threshold values used by the Canny thresholding
2246 The high threshold selects the "strong" edge pixels, which are then
2247 connected through 8-connectivity with the "weak" edge pixels selected
2248 by the low threshold.
2250 @var{low} and @var{high} threshold values must be choosen in the range
2251 [0,1], and @var{low} should be lesser or equal to @var{high}.
2253 Default value for @var{low} is @code{20/255}, and default value for @var{high}
2259 edgedetect=low=0.1:high=0.4
2264 Apply fade-in/out effect to input video.
2266 It accepts the parameters:
2267 @var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}]
2269 @var{type} specifies if the effect type, can be either "in" for
2270 fade-in, or "out" for a fade-out effect.
2272 @var{start_frame} specifies the number of the start frame for starting
2273 to apply the fade effect.
2275 @var{nb_frames} specifies the number of frames for which the fade
2276 effect has to last. At the end of the fade-in effect the output video
2277 will have the same intensity as the input video, at the end of the
2278 fade-out transition the output video will be completely black.
2280 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
2281 separated by ":". The description of the accepted options follows.
2288 @item start_frame, s
2289 See @var{start_frame}.
2292 See @var{nb_frames}.
2295 If set to 1, fade only alpha channel, if one exists on the input.
2299 A few usage examples follow, usable too as test scenarios.
2301 # fade in first 30 frames of video
2304 # fade out last 45 frames of a 200-frame video
2307 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
2308 fade=in:0:25, fade=out:975:25
2310 # make first 5 frames black, then fade in from frame 5-24
2313 # fade in alpha over first 25 frames of video
2314 fade=in:0:25:alpha=1
2319 Extract a single field from an interlaced image using stride
2320 arithmetic to avoid wasting CPU time. The output frames are marked as
2323 This filter accepts the following named options:
2326 Specify whether to extract the top (if the value is @code{0} or
2327 @code{top}) or the bottom field (if the value is @code{1} or
2331 If the option key is not specified, the first value sets the @var{type}
2332 option. For example:
2344 Transform the field order of the input video.
2346 It accepts one parameter which specifies the required field order that
2347 the input interlaced video will be transformed to. The parameter can
2348 assume one of the following values:
2352 output bottom field first
2354 output top field first
2357 Default value is "tff".
2359 Transformation is achieved by shifting the picture content up or down
2360 by one line, and filling the remaining line with appropriate picture content.
2361 This method is consistent with most broadcast field order converters.
2363 If the input video is not flagged as being interlaced, or it is already
2364 flagged as being of the required output field order then this filter does
2365 not alter the incoming video.
2367 This filter is very useful when converting to or from PAL DV material,
2368 which is bottom field first.
2372 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
2377 Buffer input images and send them when they are requested.
2379 This filter is mainly useful when auto-inserted by the libavfilter
2382 The filter does not take parameters.
2386 Convert the input video to one of the specified pixel formats.
2387 Libavfilter will try to pick one that is supported for the input to
2390 The filter accepts a list of pixel format names, separated by ":",
2391 for example "yuv420p:monow:rgb24".
2393 Some examples follow:
2395 # convert the input video to the format "yuv420p"
2398 # convert the input video to any of the formats in the list
2399 format=yuv420p:yuv444p:yuv410p
2404 Convert the video to specified constant framerate by duplicating or dropping
2405 frames as necessary.
2407 This filter accepts the following named parameters:
2411 Desired output framerate. The default is @code{25}.
2416 Possible values are:
2419 zero round towards 0
2423 round towards -infinity
2425 round towards +infinity
2429 The default is @code{near}.
2433 Alternatively, the options can be specified as a flat string:
2434 @var{fps}[:@var{round}].
2436 See also the @ref{setpts} filter.
2440 Select one frame every N.
2442 This filter accepts in input a string representing a positive
2443 integer. Default argument is @code{1}.
2448 Apply a frei0r effect to the input video.
2450 To enable compilation of this filter you need to install the frei0r
2451 header and configure FFmpeg with @code{--enable-frei0r}.
2453 The filter supports the syntax:
2455 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
2458 @var{filter_name} is the name of the frei0r effect to load. If the
2459 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
2460 is searched in each one of the directories specified by the colon (or
2461 semicolon on Windows platforms) separated list in @env{FREIOR_PATH},
2462 otherwise in the standard frei0r paths, which are in this order:
2463 @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
2464 @file{/usr/lib/frei0r-1/}.
2466 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
2467 for the frei0r effect.
2469 A frei0r effect parameter can be a boolean (whose values are specified
2470 with "y" and "n"), a double, a color (specified by the syntax
2471 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
2472 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
2473 description), a position (specified by the syntax @var{X}/@var{Y},
2474 @var{X} and @var{Y} being float numbers) and a string.
2476 The number and kind of parameters depend on the loaded effect. If an
2477 effect parameter is not specified the default value is set.
2479 Some examples follow:
2483 Apply the distort0r effect, set the first two double parameters:
2485 frei0r=distort0r:0.5:0.01
2489 Apply the colordistance effect, take a color as first parameter:
2491 frei0r=colordistance:0.2/0.3/0.4
2492 frei0r=colordistance:violet
2493 frei0r=colordistance:0x112233
2497 Apply the perspective effect, specify the top left and top right image
2500 frei0r=perspective:0.2/0.2:0.8/0.2
2504 For more information see:
2505 @url{http://frei0r.dyne.org}
2509 The filter takes one, two or three equations as parameter, separated by ':'.
2510 The first equation is mandatory and applies to the luma plane. The two
2511 following are respectively for chroma blue and chroma red planes.
2513 The filter syntax allows named parameters:
2517 the luminance expression
2519 the chrominance blue expression
2521 the chrominance red expression
2524 If one of the chrominance expression is not defined, it falls back on the other
2525 one. If none of them are specified, they will evaluate the luminance
2528 The expressions can use the following variables and functions:
2532 The sequential number of the filtered frame, starting from @code{0}.
2535 The coordinates of the current sample.
2538 The width and height of the image.
2541 Width and height scale depending on the currently filtered plane. It is the
2542 ratio between the corresponding luma plane number of pixels and the current
2543 plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and
2544 @code{0.5,0.5} for chroma planes.
2547 Time of the current frame, expressed in seconds.
2550 Return the value of the pixel at location (@var{x},@var{y}) of the current
2554 Return the value of the pixel at location (@var{x},@var{y}) of the luminance
2558 Return the value of the pixel at location (@var{x},@var{y}) of the
2559 blue-difference chroma plane.
2562 Return the value of the pixel at location (@var{x},@var{y}) of the
2563 red-difference chroma plane.
2566 For functions, if @var{x} and @var{y} are outside the area, the value will be
2567 automatically clipped to the closer edge.
2569 Some examples follow:
2573 Flip the image horizontally:
2579 Generate a bidimensional sine wave, with angle @code{PI/3} and a
2580 wavelength of 100 pixels:
2582 geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
2586 Generate a fancy enigmatic moving light:
2588 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
2594 Fix the banding artifacts that are sometimes introduced into nearly flat
2595 regions by truncation to 8bit color depth.
2596 Interpolate the gradients that should go where the bands are, and
2599 This filter is designed for playback only. Do not use it prior to
2600 lossy compression, because compression tends to lose the dither and
2601 bring back the bands.
2603 The filter takes two optional parameters, separated by ':':
2604 @var{strength}:@var{radius}
2606 @var{strength} is the maximum amount by which the filter will change
2607 any one pixel. Also the threshold for detecting nearly flat
2608 regions. Acceptable values range from .51 to 255, default value is
2609 1.2, out-of-range values will be clipped to the valid range.
2611 @var{radius} is the neighborhood to fit the gradient to. A larger
2612 radius makes for smoother gradients, but also prevents the filter from
2613 modifying the pixels near detailed regions. Acceptable values are
2614 8-32, default value is 16, out-of-range values will be clipped to the
2618 # default parameters
2627 Flip the input video horizontally.
2629 For example to horizontally flip the input video with @command{ffmpeg}:
2631 ffmpeg -i in.avi -vf "hflip" out.avi
2636 High precision/quality 3d denoise filter. This filter aims to reduce
2637 image noise producing smooth images and making still images really
2638 still. It should enhance compressibility.
2640 It accepts the following optional parameters:
2641 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
2645 a non-negative float number which specifies spatial luma strength,
2648 @item chroma_spatial
2649 a non-negative float number which specifies spatial chroma strength,
2650 defaults to 3.0*@var{luma_spatial}/4.0
2653 a float number which specifies luma temporal strength, defaults to
2654 6.0*@var{luma_spatial}/4.0
2657 a float number which specifies chroma temporal strength, defaults to
2658 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
2663 Modify the hue and/or the saturation of the input.
2665 This filter accepts the following optional named options:
2669 Specify the hue angle as a number of degrees. It accepts a float
2670 number or an expression, and defaults to 0.0.
2673 Specify the hue angle as a number of degrees. It accepts a float
2674 number or an expression, and defaults to 0.0.
2677 Specify the saturation in the [-10,10] range. It accepts a float number and
2681 The @var{h}, @var{H} and @var{s} parameters are expressions containing the
2682 following constants:
2686 frame count of the input frame starting from 0
2689 presentation timestamp of the input frame expressed in time base units
2692 frame rate of the input video, NAN if the input frame rate is unknown
2695 timestamp expressed in seconds, NAN if the input timestamp is unknown
2698 time base of the input video
2701 The options can also be set using the syntax: @var{hue}:@var{saturation}
2703 In this case @var{hue} is expressed in degrees.
2705 Some examples follow:
2708 Set the hue to 90 degrees and the saturation to 1.0:
2714 Same command but expressing the hue in radians:
2720 Same command without named options, hue must be expressed in degrees:
2726 Note that "h:s" syntax does not support expressions for the values of
2727 h and s, so the following example will issue an error:
2733 Rotate hue and make the saturation swing between 0
2734 and 2 over a period of 1 second:
2736 hue="H=2*PI*t: s=sin(2*PI*t)+1"
2740 Apply a 3 seconds saturation fade-in effect starting at 0:
2745 The general fade-in expression can be written as:
2747 hue="s=min(0\, max((t-START)/DURATION\, 1))"
2751 Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
2753 hue="s=max(0\, min(1\, (8-t)/3))"
2756 The general fade-out expression can be written as:
2758 hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
2763 @subsection Commands
2765 This filter supports the following command:
2768 Modify the hue and/or the saturation of the input video.
2769 The command accepts the same named options and syntax than when calling the
2770 filter from the command-line.
2772 If a parameter is omitted, it is kept at its current value.
2777 Interlaceing detect filter. This filter tries to detect if the input is
2778 interlaced or progressive. Top or bottom field first.
2780 @section lut, lutrgb, lutyuv
2782 Compute a look-up table for binding each pixel component input value
2783 to an output value, and apply it to input video.
2785 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
2786 to an RGB input video.
2788 These filters accept in input a ":"-separated list of options, which
2789 specify the expressions used for computing the lookup table for the
2790 corresponding pixel component values.
2792 The @var{lut} filter requires either YUV or RGB pixel formats in
2793 input, and accepts the options:
2795 @item @var{c0} (first pixel component)
2796 @item @var{c1} (second pixel component)
2797 @item @var{c2} (third pixel component)
2798 @item @var{c3} (fourth pixel component, corresponds to the alpha component)
2801 The exact component associated to each option depends on the format in
2804 The @var{lutrgb} filter requires RGB pixel formats in input, and
2805 accepts the options:
2807 @item @var{r} (red component)
2808 @item @var{g} (green component)
2809 @item @var{b} (blue component)
2810 @item @var{a} (alpha component)
2813 The @var{lutyuv} filter requires YUV pixel formats in input, and
2814 accepts the options:
2816 @item @var{y} (Y/luminance component)
2817 @item @var{u} (U/Cb component)
2818 @item @var{v} (V/Cr component)
2819 @item @var{a} (alpha component)
2822 The expressions can contain the following constants and functions:
2826 the input width and height
2829 input value for the pixel component
2832 the input value clipped in the @var{minval}-@var{maxval} range
2835 maximum value for the pixel component
2838 minimum value for the pixel component
2841 the negated value for the pixel component value clipped in the
2842 @var{minval}-@var{maxval} range , it corresponds to the expression
2843 "maxval-clipval+minval"
2846 the computed value in @var{val} clipped in the
2847 @var{minval}-@var{maxval} range
2849 @item gammaval(gamma)
2850 the computed gamma correction value of the pixel component value
2851 clipped in the @var{minval}-@var{maxval} range, corresponds to the
2853 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
2857 All expressions default to "val".
2859 Some examples follow:
2861 # negate input video
2862 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
2863 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
2865 # the above is the same as
2866 lutrgb="r=negval:g=negval:b=negval"
2867 lutyuv="y=negval:u=negval:v=negval"
2872 # remove chroma components, turns the video into a graytone image
2873 lutyuv="u=128:v=128"
2875 # apply a luma burning effect
2878 # remove green and blue components
2881 # set a constant alpha channel value on input
2882 format=rgba,lutrgb=a="maxval-minval/2"
2884 # correct luminance gamma by a 0.5 factor
2885 lutyuv=y=gammaval(0.5)
2890 Apply an MPlayer filter to the input video.
2892 This filter provides a wrapper around most of the filters of
2895 This wrapper is considered experimental. Some of the wrapped filters
2896 may not work properly and we may drop support for them, as they will
2897 be implemented natively into FFmpeg. Thus you should avoid
2898 depending on them when writing portable scripts.
2900 The filters accepts the parameters:
2901 @var{filter_name}[:=]@var{filter_params}
2903 @var{filter_name} is the name of a supported MPlayer filter,
2904 @var{filter_params} is a string containing the parameters accepted by
2907 The list of the currently supported filters follows:
2941 The parameter syntax and behavior for the listed filters are the same
2942 of the corresponding MPlayer filters. For detailed instructions check
2943 the "VIDEO FILTERS" section in the MPlayer manual.
2945 Some examples follow:
2948 Adjust gamma, brightness, contrast:
2954 Add temporal noise to input video:
2960 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
2966 This filter accepts an integer in input, if non-zero it negates the
2967 alpha component (if available). The default value in input is 0.
2971 Force libavfilter not to use any of the specified pixel formats for the
2972 input to the next filter.
2974 The filter accepts a list of pixel format names, separated by ":",
2975 for example "yuv420p:monow:rgb24".
2977 Some examples follow:
2979 # force libavfilter to use a format different from "yuv420p" for the
2980 # input to the vflip filter
2981 noformat=yuv420p,vflip
2983 # convert the input video to any of the formats not contained in the list
2984 noformat=yuv420p:yuv444p:yuv410p
2989 Pass the video source unchanged to the output.
2993 Apply video transform using libopencv.
2995 To enable this filter install libopencv library and headers and
2996 configure FFmpeg with @code{--enable-libopencv}.
2998 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
3000 @var{filter_name} is the name of the libopencv filter to apply.
3002 @var{filter_params} specifies the parameters to pass to the libopencv
3003 filter. If not specified the default values are assumed.
3005 Refer to the official libopencv documentation for more precise
3007 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
3009 Follows the list of supported libopencv filters.
3014 Dilate an image by using a specific structuring element.
3015 This filter corresponds to the libopencv function @code{cvDilate}.
3017 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
3019 @var{struct_el} represents a structuring element, and has the syntax:
3020 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
3022 @var{cols} and @var{rows} represent the number of columns and rows of
3023 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
3024 point, and @var{shape} the shape for the structuring element, and
3025 can be one of the values "rect", "cross", "ellipse", "custom".
3027 If the value for @var{shape} is "custom", it must be followed by a
3028 string of the form "=@var{filename}". The file with name
3029 @var{filename} is assumed to represent a binary image, with each
3030 printable character corresponding to a bright pixel. When a custom
3031 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
3032 or columns and rows of the read file are assumed instead.
3034 The default value for @var{struct_el} is "3x3+0x0/rect".
3036 @var{nb_iterations} specifies the number of times the transform is
3037 applied to the image, and defaults to 1.
3039 Follow some example:
3041 # use the default values
3044 # dilate using a structuring element with a 5x5 cross, iterate two times
3045 ocv=dilate=5x5+2x2/cross:2
3047 # read the shape from the file diamond.shape, iterate two times
3048 # the file diamond.shape may contain a pattern of characters like this:
3054 # the specified cols and rows are ignored (but not the anchor point coordinates)
3055 ocv=0x0+2x2/custom=diamond.shape:2
3060 Erode an image by using a specific structuring element.
3061 This filter corresponds to the libopencv function @code{cvErode}.
3063 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
3064 with the same syntax and semantics as the @ref{dilate} filter.
3068 Smooth the input video.
3070 The filter takes the following parameters:
3071 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
3073 @var{type} is the type of smooth filter to apply, and can be one of
3074 the following values: "blur", "blur_no_scale", "median", "gaussian",
3075 "bilateral". The default value is "gaussian".
3077 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
3078 parameters whose meanings depend on smooth type. @var{param1} and
3079 @var{param2} accept integer positive values or 0, @var{param3} and
3080 @var{param4} accept float values.
3082 The default value for @var{param1} is 3, the default value for the
3083 other parameters is 0.
3085 These parameters correspond to the parameters assigned to the
3086 libopencv function @code{cvSmooth}.
3091 Overlay one video on top of another.
3093 It takes two inputs and one output, the first input is the "main"
3094 video on which the second input is overlayed.
3096 It accepts the parameters: @var{x}:@var{y}[:@var{options}].
3098 @var{x} is the x coordinate of the overlayed video on the main video,
3099 @var{y} is the y coordinate. @var{x} and @var{y} are expressions containing
3100 the following parameters:
3103 @item main_w, main_h
3104 main input width and height
3107 same as @var{main_w} and @var{main_h}
3109 @item overlay_w, overlay_h
3110 overlay input width and height
3113 same as @var{overlay_w} and @var{overlay_h}
3116 @var{options} is an optional list of @var{key}=@var{value} pairs,
3119 The description of the accepted options follows.
3123 If set to 1, force the filter to accept inputs in the RGB
3124 color space. Default value is 0.
3127 Be aware that frames are taken from each input video in timestamp
3128 order, hence, if their initial timestamps differ, it is a a good idea
3129 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
3130 have them begin in the same zero timestamp, as it does the example for
3131 the @var{movie} filter.
3133 Follow some examples:
3135 # draw the overlay at 10 pixels from the bottom right
3136 # corner of the main video.
3137 overlay=main_w-overlay_w-10:main_h-overlay_h-10
3139 # insert a transparent PNG logo in the bottom left corner of the input
3140 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
3142 # insert 2 different transparent PNG logos (second logo on bottom
3144 ffmpeg -i input -i logo1 -i logo2 -filter_complex
3145 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
3147 # add a transparent color layer on top of the main video,
3148 # WxH specifies the size of the main input to the overlay filter
3149 color=red@@.3:WxH [over]; [in][over] overlay [out]
3151 # play an original video and a filtered version (here with the deshake filter)
3153 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
3155 # the previous example is the same as:
3156 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
3159 You can chain together more overlays but the efficiency of such
3160 approach is yet to be tested.
3164 Add paddings to the input image, and places the original input at the
3165 given coordinates @var{x}, @var{y}.
3167 It accepts the following parameters:
3168 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
3170 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
3171 expressions containing the following constants:
3175 the input video width and height
3178 same as @var{in_w} and @var{in_h}
3181 the output width and height, that is the size of the padded area as
3182 specified by the @var{width} and @var{height} expressions
3185 same as @var{out_w} and @var{out_h}
3188 x and y offsets as specified by the @var{x} and @var{y}
3189 expressions, or NAN if not yet specified
3192 same as @var{iw} / @var{ih}
3195 input sample aspect ratio
3198 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3201 horizontal and vertical chroma subsample values. For example for the
3202 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3205 Follows the description of the accepted parameters.
3210 Specify the size of the output image with the paddings added. If the
3211 value for @var{width} or @var{height} is 0, the corresponding input size
3212 is used for the output.
3214 The @var{width} expression can reference the value set by the
3215 @var{height} expression, and vice versa.
3217 The default value of @var{width} and @var{height} is 0.
3221 Specify the offsets where to place the input image in the padded area
3222 with respect to the top/left border of the output image.
3224 The @var{x} expression can reference the value set by the @var{y}
3225 expression, and vice versa.
3227 The default value of @var{x} and @var{y} is 0.
3231 Specify the color of the padded area, it can be the name of a color
3232 (case insensitive match) or a 0xRRGGBB[AA] sequence.
3234 The default value of @var{color} is "black".
3238 @subsection Examples
3242 Add paddings with color "violet" to the input video. Output video
3243 size is 640x480, the top-left corner of the input video is placed at
3246 pad=640:480:0:40:violet
3250 Pad the input to get an output with dimensions increased by 3/2,
3251 and put the input video at the center of the padded area:
3253 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
3257 Pad the input to get a squared output with size equal to the maximum
3258 value between the input width and height, and put the input video at
3259 the center of the padded area:
3261 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
3265 Pad the input to get a final w/h ratio of 16:9:
3267 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
3271 In case of anamorphic video, in order to set the output display aspect
3272 correctly, it is necessary to use @var{sar} in the expression,
3273 according to the relation:
3275 (ih * X / ih) * sar = output_dar
3276 X = output_dar / sar
3279 Thus the previous example needs to be modified to:
3281 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
3285 Double output size and put the input video in the bottom-right
3286 corner of the output padded area:
3288 pad="2*iw:2*ih:ow-iw:oh-ih"
3292 @section pixdesctest
3294 Pixel format descriptor test filter, mainly useful for internal
3295 testing. The output video should be equal to the input video.
3299 format=monow, pixdesctest
3302 can be used to test the monowhite pixel format descriptor definition.
3306 Suppress a TV station logo, using an image file to determine which
3307 pixels comprise the logo. It works by filling in the pixels that
3308 comprise the logo with neighboring pixels.
3310 This filter requires one argument which specifies the filter bitmap
3311 file, which can be any image format supported by libavformat. The
3312 width and height of the image file must match those of the video
3313 stream being processed.
3315 Pixels in the provided bitmap image with a value of zero are not
3316 considered part of the logo, non-zero pixels are considered part of
3317 the logo. If you use white (255) for the logo and black (0) for the
3318 rest, you will be safe. For making the filter bitmap, it is
3319 recommended to take a screen capture of a black frame with the logo
3320 visible, and then using a threshold filter followed by the erode
3321 filter once or twice.
3323 If needed, little splotches can be fixed manually. Remember that if
3324 logo pixels are not covered, the filter quality will be much
3325 reduced. Marking too many pixels as part of the logo does not hurt as
3326 much, but it will increase the amount of blurring needed to cover over
3327 the image and will destroy more information than necessary, and extra
3328 pixels will slow things down on a large logo.
3332 Scale (resize) the input video, using the libswscale library.
3334 The scale filter forces the output display aspect ratio to be the same
3335 of the input, by changing the output sample aspect ratio.
3337 This filter accepts a list of named options in the form of
3338 @var{key}=@var{value} pairs separated by ":". If the key for the first
3339 two options is not specified, the assumed keys for the first two
3340 values are @code{w} and @code{h}. If the first option has no key and
3341 can be interpreted like a video size specification, it will be used
3342 to set the video size.
3344 A description of the accepted options follows.
3348 Set the video width expression, default value is @code{iw}. See below
3349 for the list of accepted constants.
3352 Set the video heiht expression, default value is @code{ih}.
3353 See below for the list of accepted constants.
3356 Set the interlacing. It accepts the following values:
3360 force interlaced aware scaling
3363 do not apply interlaced scaling
3366 select interlaced aware scaling depending on whether the source frames
3367 are flagged as interlaced or not
3370 Default value is @code{0}.
3373 Set libswscale scaling flags. If not explictly specified the filter
3374 applies a bilinear scaling algorithm.
3377 Set the video size, the value must be a valid abbreviation or in the
3378 form @var{width}x@var{height}.
3381 The values of the @var{w} and @var{h} options are expressions
3382 containing the following constants:
3386 the input width and height
3389 same as @var{in_w} and @var{in_h}
3392 the output (cropped) width and height
3395 same as @var{out_w} and @var{out_h}
3398 same as @var{iw} / @var{ih}
3401 input sample aspect ratio
3404 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
3407 horizontal and vertical chroma subsample values. For example for the
3408 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
3411 If the input image format is different from the format requested by
3412 the next filter, the scale filter will convert the input to the
3415 If the value for @var{width} or @var{height} is 0, the respective input
3416 size is used for the output.
3418 If the value for @var{width} or @var{height} is -1, the scale filter will
3419 use, for the respective output size, a value that maintains the aspect
3420 ratio of the input image.
3422 @subsection Examples
3426 Scale the input video to a size of 200x100:
3431 This is equivalent to:
3442 Specify a size abbreviation for the output size:
3447 which can also be written as:
3453 Scale the input to 2x:
3459 The above is the same as:
3465 Scale the input to 2x with forced interlaced scaling:
3467 scale=2*iw:2*ih:interl=1
3471 Scale the input to half size:
3477 Increase the width, and set the height to the same size:
3483 Seek for Greek harmony:
3490 Increase the height, and set the width to 3/2 of the height:
3496 Increase the size, but make the size a multiple of the chroma:
3498 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
3502 Increase the width to a maximum of 500 pixels, keep the same input
3505 scale='min(500\, iw*3/2):-1'
3510 Select frames to pass in output.
3512 It accepts in input an expression, which is evaluated for each input
3513 frame. If the expression is evaluated to a non-zero value, the frame
3514 is selected and passed to the output, otherwise it is discarded.
3516 The expression can contain the following constants:
3520 the sequential number of the filtered frame, starting from 0
3523 the sequential number of the selected frame, starting from 0
3525 @item prev_selected_n
3526 the sequential number of the last selected frame, NAN if undefined
3529 timebase of the input timestamps
3532 the PTS (Presentation TimeStamp) of the filtered video frame,
3533 expressed in @var{TB} units, NAN if undefined
3536 the PTS (Presentation TimeStamp) of the filtered video frame,
3537 expressed in seconds, NAN if undefined
3540 the PTS of the previously filtered video frame, NAN if undefined
3542 @item prev_selected_pts
3543 the PTS of the last previously filtered video frame, NAN if undefined
3545 @item prev_selected_t
3546 the PTS of the last previously selected video frame, NAN if undefined
3549 the PTS of the first video frame in the video, NAN if undefined
3552 the time of the first video frame in the video, NAN if undefined
3555 the type of the filtered frame, can assume one of the following
3567 @item interlace_type
3568 the frame interlace type, can assume one of the following values:
3571 the frame is progressive (not interlaced)
3573 the frame is top-field-first
3575 the frame is bottom-field-first
3579 1 if the filtered frame is a key-frame, 0 otherwise
3582 the position in the file of the filtered frame, -1 if the information
3583 is not available (e.g. for synthetic video)
3586 value between 0 and 1 to indicate a new scene; a low value reflects a low
3587 probability for the current frame to introduce a new scene, while a higher
3588 value means the current frame is more likely to be one (see the example below)
3592 The default value of the select expression is "1".
3594 Some examples follow:
3597 # select all frames in input
3600 # the above is the same as:
3606 # select only I-frames
3607 select='eq(pict_type\,I)'
3609 # select one frame every 100
3610 select='not(mod(n\,100))'
3612 # select only frames contained in the 10-20 time interval
3613 select='gte(t\,10)*lte(t\,20)'
3615 # select only I frames contained in the 10-20 time interval
3616 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
3618 # select frames with a minimum distance of 10 seconds
3619 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
3622 Complete example to create a mosaic of the first scenes:
3625 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
3628 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
3631 @section setdar, setsar
3633 The @code{setdar} filter sets the Display Aspect Ratio for the filter
3636 This is done by changing the specified Sample (aka Pixel) Aspect
3637 Ratio, according to the following equation:
3639 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
3642 Keep in mind that the @code{setdar} filter does not modify the pixel
3643 dimensions of the video frame. Also the display aspect ratio set by
3644 this filter may be changed by later filters in the filterchain,
3645 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
3648 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
3649 the filter output video.
3651 Note that as a consequence of the application of this filter, the
3652 output display aspect ratio will change according to the equation
3655 Keep in mind that the sample aspect ratio set by the @code{setsar}
3656 filter may be changed by later filters in the filterchain, e.g. if
3657 another "setsar" or a "setdar" filter is applied.
3659 The @code{setdar} and @code{setsar} filters accept a string in the
3660 form @var{num}:@var{den} expressing an aspect ratio, or the following
3661 named options, expressed as a sequence of @var{key}=@var{value} pairs,
3666 Set the maximum integer value to use for expressing numerator and
3667 denominator when reducing the expressed aspect ratio to a rational.
3668 Default value is @code{100}.
3671 Set the aspect ratio used by the filter.
3673 The parameter can be a floating point number string, an expression, or
3674 a string of the form @var{num}:@var{den}, where @var{num} and
3675 @var{den} are the numerator and denominator of the aspect ratio. If
3676 the parameter is not specified, it is assumed the value "0".
3677 In case the form "@var{num}:@var{den}" the @code{:} character should
3681 If the keys are omitted in the named options list, the specifed values
3682 are assumed to be @var{ratio} and @var{max} in that order.
3684 For example to change the display aspect ratio to 16:9, specify:
3689 The example above is equivalent to:
3694 To change the sample aspect ratio to 10:11, specify:
3699 To set a display aspect ratio of 16:9, and specify a maximum integer value of
3700 1000 in the aspect ratio reduction, use the command:
3702 setdar=ratio='16:9':max=1000
3707 Force field for the output video frame.
3709 The @code{setfield} filter marks the interlace type field for the
3710 output frames. It does not change the input frame, but only sets the
3711 corresponding property, which affects how the frame is treated by
3712 following filters (e.g. @code{fieldorder} or @code{yadif}).
3714 This filter accepts a single option @option{mode}, which can be
3715 specified either by setting @code{mode=VALUE} either setting the
3716 value alone. Available values are:
3720 Keep the same field property.
3723 Mark the frame as bottom-field-first.
3726 Mark the frame as top-field-first.
3729 Mark the frame as progressive.
3734 Show a line containing various information for each input video frame.
3735 The input video is not modified.
3737 The shown line contains a sequence of key/value pairs of the form
3738 @var{key}:@var{value}.
3740 A description of each shown parameter follows:
3744 sequential number of the input frame, starting from 0
3747 Presentation TimeStamp of the input frame, expressed as a number of
3748 time base units. The time base unit depends on the filter input pad.
3751 Presentation TimeStamp of the input frame, expressed as a number of
3755 position of the frame in the input stream, -1 if this information in
3756 unavailable and/or meaningless (for example in case of synthetic video)
3762 sample aspect ratio of the input frame, expressed in the form
3766 size of the input frame, expressed in the form
3767 @var{width}x@var{height}
3770 interlaced mode ("P" for "progressive", "T" for top field first, "B"
3771 for bottom field first)
3774 1 if the frame is a key frame, 0 otherwise
3777 picture type of the input frame ("I" for an I-frame, "P" for a
3778 P-frame, "B" for a B-frame, "?" for unknown type).
3779 Check also the documentation of the @code{AVPictureType} enum and of
3780 the @code{av_get_picture_type_char} function defined in
3781 @file{libavutil/avutil.h}.
3784 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
3786 @item plane_checksum
3787 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
3788 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
3793 Blur the input video without impacting the outlines.
3795 The filter accepts the following parameters:
3796 @var{luma_radius}:@var{luma_strength}:@var{luma_threshold}[:@var{chroma_radius}:@var{chroma_strength}:@var{chroma_threshold}]
3798 Parameters prefixed by @var{luma} indicate that they work on the
3799 luminance of the pixels whereas parameters prefixed by @var{chroma}
3800 refer to the chrominance of the pixels.
3802 If the chroma parameters are not set, the luma parameters are used for
3803 either the luminance and the chrominance of the pixels.
3805 @var{luma_radius} or @var{chroma_radius} must be a float number in the
3806 range [0.1,5.0] that specifies the variance of the gaussian filter
3807 used to blur the image (slower if larger).
3809 @var{luma_strength} or @var{chroma_strength} must be a float number in
3810 the range [-1.0,1.0] that configures the blurring. A value included in
3811 [0.0,1.0] will blur the image whereas a value included in [-1.0,0.0]
3812 will sharpen the image.
3814 @var{luma_threshold} or @var{chroma_threshold} must be an integer in
3815 the range [-30,30] that is used as a coefficient to determine whether
3816 a pixel should be blurred or not. A value of 0 will filter all the
3817 image, a value included in [0,30] will filter flat areas and a value
3818 included in [-30,0] will filter edges.
3823 Draw subtitles on top of input video using the libass library.
3825 To enable compilation of this filter you need to configure FFmpeg with
3826 @code{--enable-libass}. This filter also requires a build with libavcodec and
3827 libavformat to convert the passed subtitles file to ASS (Advanced Substation
3828 Alpha) subtitles format.
3830 This filter accepts the following named options, expressed as a
3831 sequence of @var{key}=@var{value} pairs, separated by ":".
3835 Set the filename of the subtitle file to read. It must be specified.
3838 Specify the size of the original video, the video for which the ASS file
3839 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
3840 necessary to correctly scale the fonts if the aspect ratio has been changed.
3843 If the first key is not specified, it is assumed that the first value
3844 specifies the @option{filename}.
3846 For example, to render the file @file{sub.srt} on top of the input
3847 video, use the command:
3852 which is equivalent to:
3854 subtitles=filename=sub.srt
3859 Split input video into several identical outputs.
3861 The filter accepts a single parameter which specifies the number of outputs. If
3862 unspecified, it defaults to 2.
3866 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
3868 will create 5 copies of the input video.
3872 [in] split [splitout1][splitout2];
3873 [splitout1] crop=100:100:0:0 [cropout];
3874 [splitout2] pad=200:200:100:100 [padout];
3877 will create two separate outputs from the same input, one cropped and
3882 Scale the input by 2x and smooth using the Super2xSaI (Scale and
3883 Interpolate) pixel art scaling algorithm.
3885 Useful for enlarging pixel art images without reducing sharpness.
3891 Select the most representative frame in a given sequence of consecutive frames.
3893 It accepts as argument the frames batch size to analyze (default @var{N}=100);
3894 in a set of @var{N} frames, the filter will pick one of them, and then handle
3895 the next batch of @var{N} frames until the end.
3897 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
3898 value will result in a higher memory usage, so a high value is not recommended.
3900 The following example extract one picture each 50 frames:
3905 Complete example of a thumbnail creation with @command{ffmpeg}:
3907 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
3912 Tile several successive frames together.
3914 It accepts a list of options in the form of @var{key}=@var{value} pairs
3915 separated by ":". A description of the accepted options follows.
3920 Set the grid size (i.e. the number of lines and columns) in the form
3924 Set the outer border margin in pixels.
3927 Set the inner border thickness (i.e. the number of pixels between frames). For
3928 more advanced padding options (such as having different values for the edges),
3929 refer to the pad video filter.
3932 Set the maximum number of frames to render in the given area. It must be less
3933 than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all
3934 the area will be used.
3938 Alternatively, the options can be specified as a flat string:
3940 @var{layout}[:@var{nb_frames}[:@var{margin}[:@var{padding}]]]
3942 For example, produce 8×8 PNG tiles of all keyframes (@option{-skip_frame
3945 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
3947 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
3948 duplicating each output frame to accomodate the originally detected frame
3951 Another example to display @code{5} pictures in an area of @code{3x2} frames,
3952 with @code{7} pixels between them, and @code{2} pixels of initial margin, using
3953 mixed flat and named options:
3955 tile=3x2:nb_frames=5:padding=7:margin=2
3960 Perform various types of temporal field interlacing.
3962 Frames are counted starting from 1, so the first input frame is
3965 This filter accepts a single option @option{mode} specifying the mode,
3966 which can be specified either by specyfing @code{mode=VALUE} either
3967 specifying the value alone. Available values are:
3971 Move odd frames into the upper field, even into the lower field,
3972 generating a double height frame at half framerate.
3975 Only output even frames, odd frames are dropped, generating a frame with
3976 unchanged height at half framerate.
3979 Only output odd frames, even frames are dropped, generating a frame with
3980 unchanged height at half framerate.
3983 Expand each frame to full height, but pad alternate lines with black,
3984 generating a frame with double height at the same input framerate.
3986 @item interleave_top, 4
3987 Interleave the upper field from odd frames with the lower field from
3988 even frames, generating a frame with unchanged height at half framerate.
3990 @item interleave_bottom, 5
3991 Interleave the lower field from odd frames with the upper field from
3992 even frames, generating a frame with unchanged height at half framerate.
3994 @item interlacex2, 6
3995 Double frame rate with unchanged height. Frames are inserted each
3996 containing the second temporal field from the previous input frame and
3997 the first temporal field from the next input frame. This mode relies on
3998 the top_field_first flag. Useful for interlaced video displays with no
3999 field synchronisation.
4002 Numeric values are deprecated but are accepted for backward
4003 compatibility reasons.
4005 Default mode is @code{merge}.
4009 Transpose rows with columns in the input video and optionally flip it.
4011 This filter accepts the following named parameters:
4015 Specify the transposition direction. Can assume the following values:
4019 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
4027 Rotate by 90 degrees clockwise, that is:
4035 Rotate by 90 degrees counterclockwise, that is:
4043 Rotate by 90 degrees clockwise and vertically flip, that is:
4051 For values between 4-7, the transposition is only done if the input
4052 video geometry is portrait and not landscape. These values are
4053 deprecated, the @code{passthrough} option should be used instead.
4056 Do not apply the transposition if the input geometry matches the one
4057 specified by the specified value. It accepts the following values:
4060 Always apply transposition.
4062 Preserve portrait geometry (when @var{height} >= @var{width}).
4064 Preserve landscape geometry (when @var{width} >= @var{height}).
4067 Default value is @code{none}.
4072 Sharpen or blur the input video.
4074 It accepts the following parameters:
4075 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
4077 Negative values for the amount will blur the input video, while positive
4078 values will sharpen. All parameters are optional and default to the
4079 equivalent of the string '5:5:1.0:5:5:0.0'.
4084 Set the luma matrix horizontal size. It can be an integer between 3
4085 and 13, default value is 5.
4088 Set the luma matrix vertical size. It can be an integer between 3
4089 and 13, default value is 5.
4092 Set the luma effect strength. It can be a float number between -2.0
4093 and 5.0, default value is 1.0.
4095 @item chroma_msize_x
4096 Set the chroma matrix horizontal size. It can be an integer between 3
4097 and 13, default value is 5.
4099 @item chroma_msize_y
4100 Set the chroma matrix vertical size. It can be an integer between 3
4101 and 13, default value is 5.
4104 Set the chroma effect strength. It can be a float number between -2.0
4105 and 5.0, default value is 0.0.
4110 # Strong luma sharpen effect parameters
4113 # Strong blur of both luma and chroma parameters
4114 unsharp=7:7:-2:7:7:-2
4116 # Use the default values with @command{ffmpeg}
4117 ffmpeg -i in.avi -vf "unsharp" out.mp4
4122 Flip the input video vertically.
4125 ffmpeg -i in.avi -vf "vflip" out.avi
4130 Deinterlace the input video ("yadif" means "yet another deinterlacing
4133 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
4135 @var{mode} specifies the interlacing mode to adopt, accepts one of the
4140 output 1 frame for each frame
4142 output 1 frame for each field
4144 like 0 but skips spatial interlacing check
4146 like 1 but skips spatial interlacing check
4151 @var{parity} specifies the picture field parity assumed for the input
4152 interlaced video, accepts one of the following values:
4156 assume top field first
4158 assume bottom field first
4160 enable automatic detection
4163 Default value is -1.
4164 If interlacing is unknown or decoder does not export this information,
4165 top field first will be assumed.
4167 @var{auto} specifies if deinterlacer should trust the interlaced flag
4168 and only deinterlace frames marked as interlaced
4172 deinterlace all frames
4174 only deinterlace frames marked as interlaced
4179 @c man end VIDEO FILTERS
4181 @chapter Video Sources
4182 @c man begin VIDEO SOURCES
4184 Below is a description of the currently available video sources.
4188 Buffer video frames, and make them available to the filter chain.
4190 This source is mainly intended for a programmatic use, in particular
4191 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
4193 It accepts a list of options in the form of @var{key}=@var{value} pairs
4194 separated by ":". A description of the accepted options follows.
4199 Specify the size (width and height) of the buffered video frames.
4202 A string representing the pixel format of the buffered video frames.
4203 It may be a number corresponding to a pixel format, or a pixel format
4207 Specify the timebase assumed by the timestamps of the buffered frames.
4210 Specify the frame rate expected for the video stream.
4213 Specify the sample aspect ratio assumed by the video frames.
4216 Specify the optional parameters to be used for the scale filter which
4217 is automatically inserted when an input change is detected in the
4218 input size or format.
4223 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
4226 will instruct the source to accept video frames with size 320x240 and
4227 with format "yuv410p", assuming 1/24 as the timestamps timebase and
4228 square pixels (1:1 sample aspect ratio).
4229 Since the pixel format with name "yuv410p" corresponds to the number 6
4230 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}),
4231 this example corresponds to:
4233 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
4236 Alternatively, the options can be specified as a flat string, but this
4237 syntax is deprecated:
4239 @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}]
4243 Create a pattern generated by an elementary cellular automaton.
4245 The initial state of the cellular automaton can be defined through the
4246 @option{filename}, and @option{pattern} options. If such options are
4247 not specified an initial state is created randomly.
4249 At each new frame a new row in the video is filled with the result of
4250 the cellular automaton next generation. The behavior when the whole
4251 frame is filled is defined by the @option{scroll} option.
4253 This source accepts a list of options in the form of
4254 @var{key}=@var{value} pairs separated by ":". A description of the
4255 accepted options follows.
4259 Read the initial cellular automaton state, i.e. the starting row, from
4261 In the file, each non-whitespace character is considered an alive
4262 cell, a newline will terminate the row, and further characters in the
4263 file will be ignored.
4266 Read the initial cellular automaton state, i.e. the starting row, from
4267 the specified string.
4269 Each non-whitespace character in the string is considered an alive
4270 cell, a newline will terminate the row, and further characters in the
4271 string will be ignored.
4274 Set the video rate, that is the number of frames generated per second.
4277 @item random_fill_ratio, ratio
4278 Set the random fill ratio for the initial cellular automaton row. It
4279 is a floating point number value ranging from 0 to 1, defaults to
4282 This option is ignored when a file or a pattern is specified.
4284 @item random_seed, seed
4285 Set the seed for filling randomly the initial row, must be an integer
4286 included between 0 and UINT32_MAX. If not specified, or if explicitly
4287 set to -1, the filter will try to use a good random seed on a best
4291 Set the cellular automaton rule, it is a number ranging from 0 to 255.
4292 Default value is 110.
4295 Set the size of the output video.
4297 If @option{filename} or @option{pattern} is specified, the size is set
4298 by default to the width of the specified initial state row, and the
4299 height is set to @var{width} * PHI.
4301 If @option{size} is set, it must contain the width of the specified
4302 pattern string, and the specified pattern will be centered in the
4305 If a filename or a pattern string is not specified, the size value
4306 defaults to "320x518" (used for a randomly generated initial state).
4309 If set to 1, scroll the output upward when all the rows in the output
4310 have been already filled. If set to 0, the new generated row will be
4311 written over the top row just after the bottom row is filled.
4314 @item start_full, full
4315 If set to 1, completely fill the output with generated rows before
4316 outputting the first frame.
4317 This is the default behavior, for disabling set the value to 0.
4320 If set to 1, stitch the left and right row edges together.
4321 This is the default behavior, for disabling set the value to 0.
4324 @subsection Examples
4328 Read the initial state from @file{pattern}, and specify an output of
4331 cellauto=f=pattern:s=200x400
4335 Generate a random initial row with a width of 200 cells, with a fill
4338 cellauto=ratio=2/3:s=200x200
4342 Create a pattern generated by rule 18 starting by a single alive cell
4343 centered on an initial row with width 100:
4345 cellauto=p=@@:s=100x400:full=0:rule=18
4349 Specify a more elaborated initial pattern:
4351 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
4358 Generate a Mandelbrot set fractal, and progressively zoom towards the
4359 point specified with @var{start_x} and @var{start_y}.
4361 This source accepts a list of options in the form of
4362 @var{key}=@var{value} pairs separated by ":". A description of the
4363 accepted options follows.
4368 Set the terminal pts value. Default value is 400.
4371 Set the terminal scale value.
4372 Must be a floating point value. Default value is 0.3.
4375 Set the inner coloring mode, that is the algorithm used to draw the
4376 Mandelbrot fractal internal region.
4378 It shall assume one of the following values:
4383 Show time until convergence.
4385 Set color based on point closest to the origin of the iterations.
4390 Default value is @var{mincol}.
4393 Set the bailout value. Default value is 10.0.
4396 Set the maximum of iterations performed by the rendering
4397 algorithm. Default value is 7189.
4400 Set outer coloring mode.
4401 It shall assume one of following values:
4403 @item iteration_count
4404 Set iteration cound mode.
4405 @item normalized_iteration_count
4406 set normalized iteration count mode.
4408 Default value is @var{normalized_iteration_count}.
4411 Set frame rate, expressed as number of frames per second. Default
4415 Set frame size. Default value is "640x480".
4418 Set the initial scale value. Default value is 3.0.
4421 Set the initial x position. Must be a floating point value between
4422 -100 and 100. Default value is -0.743643887037158704752191506114774.
4425 Set the initial y position. Must be a floating point value between
4426 -100 and 100. Default value is -0.131825904205311970493132056385139.
4431 Generate various test patterns, as generated by the MPlayer test filter.
4433 The size of the generated video is fixed, and is 256x256.
4434 This source is useful in particular for testing encoding features.
4436 This source accepts an optional sequence of @var{key}=@var{value} pairs,
4437 separated by ":". The description of the accepted options follows.
4442 Specify the frame rate of the sourced video, as the number of frames
4443 generated per second. It has to be a string in the format
4444 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
4445 number or a valid video frame rate abbreviation. The default value is
4449 Set the video duration of the sourced video. The accepted syntax is:
4454 See also the function @code{av_parse_time()}.
4456 If not specified, or the expressed duration is negative, the video is
4457 supposed to be generated forever.
4461 Set the number or the name of the test to perform. Supported tests are:
4476 Default value is "all", which will cycle through the list of all tests.
4479 For example the following:
4484 will generate a "dc_luma" test pattern.
4488 Provide a frei0r source.
4490 To enable compilation of this filter you need to install the frei0r
4491 header and configure FFmpeg with @code{--enable-frei0r}.
4493 The source supports the syntax:
4495 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
4498 @var{size} is the size of the video to generate, may be a string of the
4499 form @var{width}x@var{height} or a frame size abbreviation.
4500 @var{rate} is the rate of the video to generate, may be a string of
4501 the form @var{num}/@var{den} or a frame rate abbreviation.
4502 @var{src_name} is the name to the frei0r source to load. For more
4503 information regarding frei0r and how to set the parameters read the
4504 section @ref{frei0r} in the description of the video filters.
4506 For example, to generate a frei0r partik0l source with size 200x200
4507 and frame rate 10 which is overlayed on the overlay filter main input:
4509 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
4514 Generate a life pattern.
4516 This source is based on a generalization of John Conway's life game.
4518 The sourced input represents a life grid, each pixel represents a cell
4519 which can be in one of two possible states, alive or dead. Every cell
4520 interacts with its eight neighbours, which are the cells that are
4521 horizontally, vertically, or diagonally adjacent.
4523 At each interaction the grid evolves according to the adopted rule,
4524 which specifies the number of neighbor alive cells which will make a
4525 cell stay alive or born. The @option{rule} option allows to specify
4528 This source accepts a list of options in the form of
4529 @var{key}=@var{value} pairs separated by ":". A description of the
4530 accepted options follows.
4534 Set the file from which to read the initial grid state. In the file,
4535 each non-whitespace character is considered an alive cell, and newline
4536 is used to delimit the end of each row.
4538 If this option is not specified, the initial grid is generated
4542 Set the video rate, that is the number of frames generated per second.
4545 @item random_fill_ratio, ratio
4546 Set the random fill ratio for the initial random grid. It is a
4547 floating point number value ranging from 0 to 1, defaults to 1/PHI.
4548 It is ignored when a file is specified.
4550 @item random_seed, seed
4551 Set the seed for filling the initial random grid, must be an integer
4552 included between 0 and UINT32_MAX. If not specified, or if explicitly
4553 set to -1, the filter will try to use a good random seed on a best
4559 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
4560 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
4561 @var{NS} specifies the number of alive neighbor cells which make a
4562 live cell stay alive, and @var{NB} the number of alive neighbor cells
4563 which make a dead cell to become alive (i.e. to "born").
4564 "s" and "b" can be used in place of "S" and "B", respectively.
4566 Alternatively a rule can be specified by an 18-bits integer. The 9
4567 high order bits are used to encode the next cell state if it is alive
4568 for each number of neighbor alive cells, the low order bits specify
4569 the rule for "borning" new cells. Higher order bits encode for an
4570 higher number of neighbor cells.
4571 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
4572 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
4574 Default value is "S23/B3", which is the original Conway's game of life
4575 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
4576 cells, and will born a new cell if there are three alive cells around
4580 Set the size of the output video.
4582 If @option{filename} is specified, the size is set by default to the
4583 same size of the input file. If @option{size} is set, it must contain
4584 the size specified in the input file, and the initial grid defined in
4585 that file is centered in the larger resulting area.
4587 If a filename is not specified, the size value defaults to "320x240"
4588 (used for a randomly generated initial grid).
4591 If set to 1, stitch the left and right grid edges together, and the
4592 top and bottom edges also. Defaults to 1.
4595 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
4596 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
4597 value from 0 to 255.
4600 Set the color of living (or new born) cells.
4603 Set the color of dead cells. If @option{mold} is set, this is the first color
4604 used to represent a dead cell.
4607 Set mold color, for definitely dead and moldy cells.
4610 @subsection Examples
4614 Read a grid from @file{pattern}, and center it on a grid of size
4617 life=f=pattern:s=300x300
4621 Generate a random grid of size 200x200, with a fill ratio of 2/3:
4623 life=ratio=2/3:s=200x200
4627 Specify a custom rule for evolving a randomly generated grid:
4633 Full example with slow death effect (mold) using @command{ffplay}:
4635 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
4639 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
4641 The @code{color} source provides an uniformly colored input.
4643 The @code{nullsrc} source returns unprocessed video frames. It is
4644 mainly useful to be employed in analysis / debugging tools, or as the
4645 source for filters which ignore the input data.
4647 The @code{rgbtestsrc} source generates an RGB test pattern useful for
4648 detecting RGB vs BGR issues. You should see a red, green and blue
4649 stripe from top to bottom.
4651 The @code{smptebars} source generates a color bars pattern, based on
4652 the SMPTE Engineering Guideline EG 1-1990.
4654 The @code{testsrc} source generates a test video pattern, showing a
4655 color pattern, a scrolling gradient and a timestamp. This is mainly
4656 intended for testing purposes.
4658 These sources accept an optional sequence of @var{key}=@var{value} pairs,
4659 separated by ":". The description of the accepted options follows.
4664 Specify the color of the source, only used in the @code{color}
4665 source. It can be the name of a color (case insensitive match) or a
4666 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
4667 default value is "black".
4670 Specify the size of the sourced video, it may be a string of the form
4671 @var{width}x@var{height}, or the name of a size abbreviation. The
4672 default value is "320x240".
4675 Specify the frame rate of the sourced video, as the number of frames
4676 generated per second. It has to be a string in the format
4677 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
4678 number or a valid video frame rate abbreviation. The default value is
4682 Set the sample aspect ratio of the sourced video.
4685 Set the video duration of the sourced video. The accepted syntax is:
4687 [-]HH[:MM[:SS[.m...]]]
4690 See also the function @code{av_parse_time()}.
4692 If not specified, or the expressed duration is negative, the video is
4693 supposed to be generated forever.
4696 Set the number of decimals to show in the timestamp, only used in the
4697 @code{testsrc} source.
4699 The displayed timestamp value will correspond to the original
4700 timestamp value multiplied by the power of 10 of the specified
4701 value. Default value is 0.
4704 For example the following:
4706 testsrc=duration=5.3:size=qcif:rate=10
4709 will generate a video with a duration of 5.3 seconds, with size
4710 176x144 and a frame rate of 10 frames per second.
4712 The following graph description will generate a red source
4713 with an opacity of 0.2, with size "qcif" and a frame rate of 10
4716 color=c=red@@0.2:s=qcif:r=10
4719 If the input content is to be ignored, @code{nullsrc} can be used. The
4720 following command generates noise in the luminance plane by employing
4721 the @code{geq} filter:
4723 nullsrc=s=256x256, geq=random(1)*255:128:128
4726 @c man end VIDEO SOURCES
4728 @chapter Video Sinks
4729 @c man begin VIDEO SINKS
4731 Below is a description of the currently available video sinks.
4735 Buffer video frames, and make them available to the end of the filter
4738 This sink is mainly intended for a programmatic use, in particular
4739 through the interface defined in @file{libavfilter/buffersink.h}.
4741 It does not require a string parameter in input, but you need to
4742 specify a pointer to a list of supported pixel formats terminated by
4743 -1 in the opaque parameter provided to @code{avfilter_init_filter}
4744 when initializing this sink.
4748 Null video sink, do absolutely nothing with the input video. It is
4749 mainly useful as a template and to be employed in analysis / debugging
4752 @c man end VIDEO SINKS
4754 @chapter Multimedia Filters
4755 @c man begin MULTIMEDIA FILTERS
4757 Below is a description of the currently available multimedia filters.
4759 @section asendcmd, sendcmd
4761 Send commands to filters in the filtergraph.
4763 These filters read commands to be sent to other filters in the
4766 @code{asendcmd} must be inserted between two audio filters,
4767 @code{sendcmd} must be inserted between two video filters, but apart
4768 from that they act the same way.
4770 The specification of commands can be provided in the filter arguments
4771 with the @var{commands} option, or in a file specified by the
4772 @var{filename} option.
4774 These filters accept the following options:
4777 Set the commands to be read and sent to the other filters.
4779 Set the filename of the commands to be read and sent to the other
4783 @subsection Commands syntax
4785 A commands description consists of a sequence of interval
4786 specifications, comprising a list of commands to be executed when a
4787 particular event related to that interval occurs. The occurring event
4788 is typically the current frame time entering or leaving a given time
4791 An interval is specified by the following syntax:
4793 @var{START}[-@var{END}] @var{COMMANDS};
4796 The time interval is specified by the @var{START} and @var{END} times.
4797 @var{END} is optional and defaults to the maximum time.
4799 The current frame time is considered within the specified interval if
4800 it is included in the interval [@var{START}, @var{END}), that is when
4801 the time is greater or equal to @var{START} and is lesser than
4804 @var{COMMANDS} consists of a sequence of one or more command
4805 specifications, separated by ",", relating to that interval. The
4806 syntax of a command specification is given by:
4808 [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG}
4811 @var{FLAGS} is optional and specifies the type of events relating to
4812 the time interval which enable sending the specified command, and must
4813 be a non-null sequence of identifier flags separated by "+" or "|" and
4814 enclosed between "[" and "]".
4816 The following flags are recognized:
4819 The command is sent when the current frame timestamp enters the
4820 specified interval. In other words, the command is sent when the
4821 previous frame timestamp was not in the given interval, and the
4825 The command is sent when the current frame timestamp leaves the
4826 specified interval. In other words, the command is sent when the
4827 previous frame timestamp was in the given interval, and the
4831 If @var{FLAGS} is not specified, a default value of @code{[enter]} is
4834 @var{TARGET} specifies the target of the command, usually the name of
4835 the filter class or a specific filter instance name.
4837 @var{COMMAND} specifies the name of the command for the target filter.
4839 @var{ARG} is optional and specifies the optional list of argument for
4840 the given @var{COMMAND}.
4842 Between one interval specification and another, whitespaces, or
4843 sequences of characters starting with @code{#} until the end of line,
4844 are ignored and can be used to annotate comments.
4846 A simplified BNF description of the commands specification syntax
4849 @var{COMMAND_FLAG} ::= "enter" | "leave"
4850 @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}]
4851 @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}]
4852 @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}]
4853 @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS}
4854 @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}]
4857 @subsection Examples
4861 Specify audio tempo change at second 4:
4863 asendcmd=c='4.0 atempo tempo 1.5',atempo
4867 Specify a list of drawtext and hue commands in a file.
4869 # show text in the interval 5-10
4870 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
4871 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
4873 # desaturate the image in the interval 15-20
4874 15.0-20.0 [enter] hue reinit s=0,
4875 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
4876 [leave] hue reinit s=1,
4877 [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
4879 # apply an exponential saturation fade-out effect, starting from time 25
4880 25 [enter] hue s=exp(t-25)
4883 A filtergraph allowing to read and process the above command list
4884 stored in a file @file{test.cmd}, can be specified with:
4886 sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
4891 @section asetpts, setpts
4893 Change the PTS (presentation timestamp) of the input frames.
4895 @code{asetpts} works on audio frames, @code{setpts} on video frames.
4897 Accept in input an expression evaluated through the eval API, which
4898 can contain the following constants:
4902 frame rate, only defined for constant frame-rate video
4905 the presentation timestamp in input
4908 the count of the input frame, starting from 0.
4910 @item NB_CONSUMED_SAMPLES
4911 the number of consumed samples, not including the current frame (only
4915 the number of samples in the current frame (only audio)
4921 the PTS of the first frame
4924 the time in seconds of the first frame
4927 tell if the current frame is interlaced
4930 the time in seconds of the current frame
4936 original position in the file of the frame, or undefined if undefined
4937 for the current frame
4943 previous input time in seconds
4949 previous output time in seconds
4952 @subsection Examples
4956 Start counting PTS from zero
4962 Apply fast motion effect:
4968 Apply slow motion effect:
4974 Set fixed rate of 25 frames per second:
4980 Set fixed rate 25 fps with some jitter:
4982 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
4986 Apply an offset of 10 seconds to the input PTS:
4994 EBU R128 scanner filter. This filter takes an audio stream as input and outputs
4995 it unchanged. By default, it logs a message at a frequency of 10Hz with the
4996 Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
4997 Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
4999 The filter also has a video output (see the @var{video} option) with a real
5000 time graph to observe the loudness evolution. The graphic contains the logged
5001 message mentioned above, so it is not printed anymore when this option is set,
5002 unless the verbose logging is set. The main graphing area contains the
5003 short-term loudness (3 seconds of analysis), and the gauge on the right is for
5004 the momentary loudness (400 milliseconds).
5006 More information about the Loudness Recommendation EBU R128 on
5007 @url{http://tech.ebu.ch/loudness}.
5009 The filter accepts the following named parameters:
5014 Activate the video output. The audio stream is passed unchanged whether this
5015 option is set or no. The video stream will be the first output stream if
5016 activated. Default is @code{0}.
5019 Set the video size. This option is for video only. Default and minimum
5020 resolution is @code{640x480}.
5023 Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
5024 @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
5025 other integer value between this range is allowed.
5029 Example of real-time graph using @command{ffplay}, with a EBU scale meter +18:
5031 ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
5034 Run an analysis with @command{ffmpeg}:
5036 ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
5039 @section settb, asettb
5041 Set the timebase to use for the output frames timestamps.
5042 It is mainly useful for testing timebase configuration.
5044 It accepts in input an arithmetic expression representing a rational.
5045 The expression can contain the constants "AVTB" (the
5046 default timebase), "intb" (the input timebase) and "sr" (the sample rate,
5049 The default value for the input is "intb".
5051 @subsection Examples
5055 Set the timebase to 1/25:
5061 Set the timebase to 1/10:
5067 Set the timebase to 1001/1000:
5073 Set the timebase to 2*intb:
5079 Set the default timebase value:
5087 Concatenate audio and video streams, joining them together one after the
5090 The filter works on segments of synchronized video and audio streams. All
5091 segments must have the same number of streams of each type, and that will
5092 also be the number of streams at output.
5094 The filter accepts the following named parameters:
5098 Set the number of segments. Default is 2.
5101 Set the number of output video streams, that is also the number of video
5102 streams in each segment. Default is 1.
5105 Set the number of output audio streams, that is also the number of video
5106 streams in each segment. Default is 0.
5109 Activate unsafe mode: do not fail if segments have a different format.
5113 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
5114 @var{a} audio outputs.
5116 There are @var{n}×(@var{v}+@var{a}) inputs: first the inputs for the first
5117 segment, in the same order as the outputs, then the inputs for the second
5120 Related streams do not always have exactly the same duration, for various
5121 reasons including codec frame size or sloppy authoring. For that reason,
5122 related synchronized streams (e.g. a video and its audio track) should be
5123 concatenated at once. The concat filter will use the duration of the longest
5124 stream in each segment (except the last one), and if necessary pad shorter
5125 audio streams with silence.
5127 For this filter to work correctly, all segments must start at timestamp 0.
5129 All corresponding streams must have the same parameters in all segments; the
5130 filtering system will automatically select a common pixel format for video
5131 streams, and a common sample format, sample rate and channel layout for
5132 audio streams, but other settings, such as resolution, must be converted
5133 explicitly by the user.
5135 Different frame rates are acceptable but will result in variable frame rate
5136 at output; be sure to configure the output file to handle it.
5141 Concatenate an opening, an episode and an ending, all in bilingual version
5142 (video in stream 0, audio in streams 1 and 2):
5144 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
5145 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
5146 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
5147 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
5151 Concatenate two parts, handling audio and video separately, using the
5152 (a)movie sources, and adjusting the resolution:
5154 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
5155 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
5156 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
5158 Note that a desync will happen at the stitch if the audio and video streams
5159 do not have exactly the same duration in the first file.
5163 @section showspectrum
5165 Convert input audio to a video output, representing the audio frequency
5168 The filter accepts the following named parameters:
5171 Specify the video size for the output. Default value is @code{640x480}.
5173 Specify if the spectrum should slide along the window. Default value is
5177 The usage is very similar to the showwaves filter; see the examples in that
5182 Convert input audio to a video output, representing the samples waves.
5184 The filter accepts the following named parameters:
5188 Set the number of samples which are printed on the same column. A
5189 larger value will decrease the frame rate. Must be a positive
5190 integer. This option can be set only if the value for @var{rate}
5191 is not explicitly specified.
5194 Set the (approximate) output frame rate. This is done by setting the
5195 option @var{n}. Default value is "25".
5198 Specify the video size for the output. Default value is "600x240".
5201 Some examples follow.
5204 Output the input file audio and the corresponding video representation
5207 amovie=a.mp3,asplit[out0],showwaves[out1]
5211 Create a synthetic signal and show it with showwaves, forcing a
5212 framerate of 30 frames per second:
5214 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
5218 @c man end MULTIMEDIA FILTERS
5220 @chapter Multimedia Sources
5221 @c man begin MULTIMEDIA SOURCES
5223 Below is a description of the currently available multimedia sources.
5227 This is the same as @ref{src_movie} source, except it selects an audio
5233 Read audio and/or video stream(s) from a movie container.
5235 It accepts the syntax: @var{movie_name}[:@var{options}] where
5236 @var{movie_name} is the name of the resource to read (not necessarily
5237 a file but also a device or a stream accessed through some protocol),
5238 and @var{options} is an optional sequence of @var{key}=@var{value}
5239 pairs, separated by ":".
5241 The description of the accepted options follows.
5245 @item format_name, f
5246 Specifies the format assumed for the movie to read, and can be either
5247 the name of a container or an input device. If not specified the
5248 format is guessed from @var{movie_name} or by probing.
5250 @item seek_point, sp
5251 Specifies the seek point in seconds, the frames will be output
5252 starting from this seek point, the parameter is evaluated with
5253 @code{av_strtod} so the numerical value may be suffixed by an IS
5254 postfix. Default value is "0".
5257 Specifies the streams to read. Several streams can be specified, separated
5258 by "+". The source will then have as many outputs, in the same order. The
5259 syntax is explained in the @ref{Stream specifiers} chapter. Two special
5260 names, "dv" and "da" specify respectively the default (best suited) video
5261 and audio stream. Default is "dv", or "da" if the filter is called as
5264 @item stream_index, si
5265 Specifies the index of the video stream to read. If the value is -1,
5266 the best suited video stream will be automatically selected. Default
5267 value is "-1". Deprecated. If the filter is called "amovie", it will select
5268 audio instead of video.
5271 Specifies how many times to read the stream in sequence.
5272 If the value is less than 1, the stream will be read again and again.
5273 Default value is "1".
5275 Note that when the movie is looped the source timestamps are not
5276 changed, so it will generate non monotonically increasing timestamps.
5279 This filter allows to overlay a second video on top of main input of
5280 a filtergraph as shown in this graph:
5282 input -----------> deltapts0 --> overlay --> output
5285 movie --> scale--> deltapts1 -------+
5288 Some examples follow.
5292 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
5293 on top of the input labelled as "in":
5295 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
5296 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
5300 Read from a video4linux2 device, and overlay it on top of the input
5303 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
5304 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
5308 Read the first video stream and the audio stream with id 0x81 from
5309 dvd.vob; the video is connected to the pad named "video" and the audio is
5310 connected to the pad named "audio":
5312 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
5316 @c man end MULTIMEDIA SOURCES