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.
86 @chapter Filtergraph description
87 @c man begin FILTERGRAPH DESCRIPTION
89 A filtergraph is a directed graph of connected filters. It can contain
90 cycles, and there can be multiple links between a pair of
91 filters. Each link has one input pad on one side connecting it to one
92 filter from which it takes its input, and one output pad on the other
93 side connecting it to the one filter accepting its output.
95 Each filter in a filtergraph is an instance of a filter class
96 registered in the application, which defines the features and the
97 number of input and output pads of the filter.
99 A filter with no input pads is called a "source", a filter with no
100 output pads is called a "sink".
102 @anchor{Filtergraph syntax}
103 @section Filtergraph syntax
105 A filtergraph can be represented using a textual representation, which is
106 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
107 options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
108 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
109 @file{libavfilter/avfiltergraph.h}.
111 A filterchain consists of a sequence of connected filters, each one
112 connected to the previous one in the sequence. A filterchain is
113 represented by a list of ","-separated filter descriptions.
115 A filtergraph consists of a sequence of filterchains. A sequence of
116 filterchains is represented by a list of ";"-separated filterchain
119 A filter is represented by a string of the form:
120 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
122 @var{filter_name} is the name of the filter class of which the
123 described filter is an instance of, and has to be the name of one of
124 the filter classes registered in the program.
125 The name of the filter class is optionally followed by a string
128 @var{arguments} is a string which contains the parameters used to
129 initialize the filter instance, and are described in the filter
132 The list of arguments can be quoted using the character "'" as initial
133 and ending mark, and the character '\' for escaping the characters
134 within the quoted text; otherwise the argument string is considered
135 terminated when the next special character (belonging to the set
136 "[]=;,") is encountered.
138 The name and arguments of the filter are optionally preceded and
139 followed by a list of link labels.
140 A link label allows to name a link and associate it to a filter output
141 or input pad. The preceding labels @var{in_link_1}
142 ... @var{in_link_N}, are associated to the filter input pads,
143 the following labels @var{out_link_1} ... @var{out_link_M}, are
144 associated to the output pads.
146 When two link labels with the same name are found in the
147 filtergraph, a link between the corresponding input and output pad is
150 If an output pad is not labelled, it is linked by default to the first
151 unlabelled input pad of the next filter in the filterchain.
152 For example in the filterchain:
154 nullsrc, split[L1], [L2]overlay, nullsink
156 the split filter instance has two output pads, and the overlay filter
157 instance two input pads. The first output pad of split is labelled
158 "L1", the first input pad of overlay is labelled "L2", and the second
159 output pad of split is linked to the second input pad of overlay,
160 which are both unlabelled.
162 In a complete filterchain all the unlabelled filter input and output
163 pads must be connected. A filtergraph is considered valid if all the
164 filter input and output pads of all the filterchains are connected.
166 Libavfilter will automatically insert scale filters where format
167 conversion is required. It is possible to specify swscale flags
168 for those automatically inserted scalers by prepending
169 @code{sws_flags=@var{flags};}
170 to the filtergraph description.
172 Follows a BNF description for the filtergraph syntax:
174 @var{NAME} ::= sequence of alphanumeric characters and '_'
175 @var{LINKLABEL} ::= "[" @var{NAME} "]"
176 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
177 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
178 @var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
179 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
180 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
183 @c man end FILTERGRAPH DESCRIPTION
185 @chapter Audio Filters
186 @c man begin AUDIO FILTERS
188 When you configure your FFmpeg build, you can disable any of the
189 existing filters using @code{--disable-filters}.
190 The configure output will show the audio filters included in your
193 Below is a description of the currently available audio filters.
197 Convert the input audio format to the specified formats.
199 The filter accepts a string of the form:
200 "@var{sample_format}:@var{channel_layout}".
202 @var{sample_format} specifies the sample format, and can be a string or the
203 corresponding numeric value defined in @file{libavutil/samplefmt.h}. Use 'p'
204 suffix for a planar sample format.
206 @var{channel_layout} specifies the channel layout, and can be a string
207 or the corresponding number value defined in @file{libavutil/audioconvert.h}.
209 The special parameter "auto", signifies that the filter will
210 automatically select the output format depending on the output filter.
212 Some examples follow.
216 Convert input to float, planar, stereo:
222 Convert input to unsigned 8-bit, automatically select out channel layout:
230 Convert the input audio to one of the specified formats. The framework will
231 negotiate the most appropriate format to minimize conversions.
233 The filter accepts the following named parameters:
237 A comma-separated list of requested sample formats.
240 A comma-separated list of requested sample rates.
242 @item channel_layouts
243 A comma-separated list of requested channel layouts.
247 If a parameter is omitted, all values are allowed.
249 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
251 aformat=sample_fmts\=u8\,s16:channel_layouts\=stereo
256 Merge two or more audio streams into a single multi-channel stream.
258 The filter accepts the following named options:
263 Set the number of inputs. Default is 2.
267 If the channel layouts of the inputs are disjoint, and therefore compatible,
268 the channel layout of the output will be set accordingly and the channels
269 will be reordered as necessary. If the channel layouts of the inputs are not
270 disjoint, the output will have all the channels of the first input then all
271 the channels of the second input, in that order, and the channel layout of
272 the output will be the default value corresponding to the total number of
275 For example, if the first input is in 2.1 (FL+FR+LF) and the second input
276 is FC+BL+BR, then the output will be in 5.1, with the channels in the
277 following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
278 first input, b1 is the first channel of the second input).
280 On the other hand, if both input are in stereo, the output channels will be
281 in the default order: a1, a2, b1, b2, and the channel layout will be
282 arbitrarily set to 4.0, which may or may not be the expected value.
284 All inputs must have the same sample rate, and format.
286 If inputs do not have the same duration, the output will stop with the
289 Example: merge two mono files into a stereo stream:
291 amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
294 Example: multiple merges:
297 amovie=input.mkv:si=0 [a0];
298 amovie=input.mkv:si=1 [a1];
299 amovie=input.mkv:si=2 [a2];
300 amovie=input.mkv:si=3 [a3];
301 amovie=input.mkv:si=4 [a4];
302 amovie=input.mkv:si=5 [a5];
303 [a0][a1][a2][a3][a4][a5] amerge=inputs=6" -c:a pcm_s16le output.mkv
308 Mixes multiple audio inputs into a single output.
312 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
314 will mix 3 input audio streams to a single output with the same duration as the
315 first input and a dropout transition time of 3 seconds.
317 The filter accepts the following named parameters:
321 Number of inputs. If unspecified, it defaults to 2.
324 How to determine the end-of-stream.
328 Duration of longest input. (default)
331 Duration of shortest input.
334 Duration of first input.
338 @item dropout_transition
339 Transition time, in seconds, for volume renormalization when an input
340 stream ends. The default value is 2 seconds.
346 Pass the audio source unchanged to the output.
350 Resample the input audio to the specified sample rate.
352 The filter accepts exactly one parameter, the output sample rate. If not
353 specified then the filter will automatically convert between its input
354 and output sample rates.
356 For example, to resample the input audio to 44100Hz:
361 @section asetnsamples
363 Set the number of samples per each output audio frame.
365 The last output packet may contain a different number of samples, as
366 the filter will flush all the remaining samples when the input audio
369 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
374 @item nb_out_samples, n
375 Set the number of frames per each output audio frame. The number is
376 intended as the number of samples @emph{per each channel}.
377 Default value is 1024.
380 If set to 1, the filter will pad the last audio frame with zeroes, so
381 that the last frame will contain the same number of samples as the
382 previous ones. Default value is 1.
385 For example, to set the number of per-frame samples to 1234 and
386 disable padding for the last frame, use:
388 asetnsamples=n=1234:p=0
393 Show a line containing various information for each input audio frame.
394 The input audio is not modified.
396 The shown line contains a sequence of key/value pairs of the form
397 @var{key}:@var{value}.
399 A description of each shown parameter follows:
403 sequential number of the input frame, starting from 0
406 presentation TimeStamp of the input frame, expressed as a number of
407 time base units. The time base unit depends on the filter input pad, and
408 is usually 1/@var{sample_rate}.
411 presentation TimeStamp of the input frame, expressed as a number of
415 position of the frame in the input stream, -1 if this information in
416 unavailable and/or meaningless (for example in case of synthetic audio)
422 channel layout description
425 number of samples (per each channel) contained in the filtered frame
428 sample rate for the audio frame
431 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
434 Adler-32 checksum (printed in hexadecimal) for each input frame plane,
435 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3} @var{c4} @var{c5}
441 Split input audio into several identical outputs.
443 The filter accepts a single parameter which specifies the number of outputs. If
444 unspecified, it defaults to 2.
448 [in] asplit [out0][out1]
451 will create two separate outputs from the same input.
453 To create 3 or more outputs, you need to specify the number of
456 [in] asplit=3 [out0][out1][out2]
460 ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
462 will create 5 copies of the input audio.
467 Forward two audio streams and control the order the buffers are forwarded.
469 The argument to the filter is an expression deciding which stream should be
470 forwarded next: if the result is negative, the first stream is forwarded; if
471 the result is positive or zero, the second stream is forwarded. It can use
472 the following variables:
476 number of buffers forwarded so far on each stream
478 number of samples forwarded so far on each stream
480 current timestamp of each stream
483 The default value is @code{t1-t2}, which means to always forward the stream
484 that has a smaller timestamp.
486 Example: stress-test @code{amerge} by randomly sending buffers on the wrong
487 input, while avoiding too much of a desynchronization:
489 amovie=file.ogg [a] ; amovie=file.mp3 [b] ;
490 [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ;
498 The filter accepts exactly one parameter, the audio tempo. If not
499 specified then the filter will assume nominal 1.0 tempo. Tempo must
500 be in the [0.5, 2.0] range.
502 For example, to slow down audio to 80% tempo:
507 For example, to speed up audio to 125% tempo:
514 Make audio easier to listen to on headphones.
516 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
517 so that when listened to on headphones the stereo image is moved from
518 inside your head (standard for headphones) to outside and in front of
519 the listener (standard for speakers).
525 Mix channels with specific gain levels. The filter accepts the output
526 channel layout followed by a set of channels definitions.
528 This filter is also designed to remap efficiently the channels of an audio
531 The filter accepts parameters of the form:
532 "@var{l}:@var{outdef}:@var{outdef}:..."
536 output channel layout or number of channels
539 output channel specification, of the form:
540 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
543 output channel to define, either a channel name (FL, FR, etc.) or a channel
544 number (c0, c1, etc.)
547 multiplicative coefficient for the channel, 1 leaving the volume unchanged
550 input channel to use, see out_name for details; it is not possible to mix
551 named and numbered input channels
554 If the `=' in a channel specification is replaced by `<', then the gains for
555 that specification will be renormalized so that the total is 1, thus
556 avoiding clipping noise.
558 @subsection Mixing examples
560 For example, if you want to down-mix from stereo to mono, but with a bigger
561 factor for the left channel:
563 pan=1:c0=0.9*c0+0.1*c1
566 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
569 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
572 Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system
573 that should be preferred (see "-ac" option) unless you have very specific
576 @subsection Remapping examples
578 The channel remapping will be effective if, and only if:
581 @item gain coefficients are zeroes or ones,
582 @item only one input per channel output,
585 If all these conditions are satisfied, the filter will notify the user ("Pure
586 channel mapping detected"), and use an optimized and lossless method to do the
589 For example, if you have a 5.1 source and want a stereo audio stream by
590 dropping the extra channels:
592 pan="stereo: c0=FL : c1=FR"
595 Given the same source, you can also switch front left and front right channels
596 and keep the input channel layout:
598 pan="5.1: c0=c1 : c1=c0 : c2=c2 : c3=c3 : c4=c4 : c5=c5"
601 If the input is a stereo audio stream, you can mute the front left channel (and
602 still keep the stereo channel layout) with:
607 Still with a stereo audio stream input, you can copy the right channel in both
608 front left and right:
610 pan="stereo: c0=FR : c1=FR"
613 @section silencedetect
615 Detect silence in an audio stream.
617 This filter logs a message when it detects that the input audio volume is less
618 or equal to a noise tolerance value for a duration greater or equal to the
619 minimum detected noise duration.
621 The printed times and duration are expressed in seconds.
625 Set silence duration until notification (default is 2 seconds).
628 Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
629 specified value) or amplitude ratio. Default is -60dB, or 0.001.
632 Detect 5 seconds of silence with -50dB noise tolerance:
634 silencedetect=n=-50dB:d=5
637 Complete example with @command{ffmpeg} to detect silence with 0.0001 noise
638 tolerance in @file{silence.mp3}:
640 ffmpeg -f lavfi -i amovie=silence.mp3,silencedetect=noise=0.0001 -f null -
645 Adjust the input audio volume.
647 The filter accepts exactly one parameter @var{vol}, which expresses
648 how the audio volume will be increased or decreased.
650 Output values are clipped to the maximum value.
652 If @var{vol} is expressed as a decimal number, the output audio
653 volume is given by the relation:
655 @var{output_volume} = @var{vol} * @var{input_volume}
658 If @var{vol} is expressed as a decimal number followed by the string
659 "dB", the value represents the requested change in decibels of the
660 input audio power, and the output audio volume is given by the
663 @var{output_volume} = 10^(@var{vol}/20) * @var{input_volume}
666 Otherwise @var{vol} is considered an expression and its evaluated
667 value is used for computing the output audio volume according to the
670 Default value for @var{vol} is 1.0.
676 Half the input audio volume:
681 The above example is equivalent to:
687 Decrease input audio power by 12 decibels:
694 Synchronize audio data with timestamps by squeezing/stretching it and/or
695 dropping samples/adding silence when needed.
697 The filter accepts the following named parameters:
701 Enable stretching/squeezing the data to make it match the timestamps.
704 Minimum difference between timestamps and audio data (in seconds) to trigger
705 adding/dropping samples.
708 Maximum compensation in samples per second.
711 Assume the first pts should be this value.
712 This allows for padding/trimming at the start of stream. By default, no
713 assumption is made about the first frame's expected pts, so no padding or
714 trimming is done. For example, this could be set to 0 to pad the beginning with
715 silence if an audio stream starts after the video stream.
719 @section channelsplit
720 Split each channel in input audio stream into a separate output stream.
722 This filter accepts the following named parameters:
725 Channel layout of the input stream. Default is "stereo".
728 For example, assuming a stereo input MP3 file
730 ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
732 will create an output Matroska file with two audio streams, one containing only
733 the left channel and the other the right channel.
735 To split a 5.1 WAV file into per-channel files
737 ffmpeg -i in.wav -filter_complex
738 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
739 -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
740 front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
745 Remap input channels to new locations.
747 This filter accepts the following named parameters:
750 Channel layout of the output stream.
753 Map channels from input to output. The argument is a comma-separated list of
754 mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
755 @var{in_channel} form. @var{in_channel} can be either the name of the input
756 channel (e.g. FL for front left) or its index in the input channel layout.
757 @var{out_channel} is the name of the output channel or its index in the output
758 channel layout. If @var{out_channel} is not given then it is implicitly an
759 index, starting with zero and increasing by one for each mapping.
762 If no mapping is present, the filter will implicitly map input channels to
763 output channels preserving index.
765 For example, assuming a 5.1+downmix input MOV file
767 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL\,DR-FR' out.wav
769 will create an output WAV file tagged as stereo from the downmix channels of
772 To fix a 5.1 WAV improperly encoded in AAC's native channel order
774 ffmpeg -i in.wav -filter 'channelmap=1\,2\,0\,5\,3\,4:channel_layout=5.1' out.wav
778 Join multiple input streams into one multi-channel stream.
780 The filter accepts the following named parameters:
784 Number of input streams. Defaults to 2.
787 Desired output channel layout. Defaults to stereo.
790 Map channels from inputs to output. The argument is a comma-separated list of
791 mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
792 form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
793 can be either the name of the input channel (e.g. FL for front left) or its
794 index in the specified input stream. @var{out_channel} is the name of the output
798 The filter will attempt to guess the mappings when those are not specified
799 explicitly. It does so by first trying to find an unused matching input channel
800 and if that fails it picks the first unused input channel.
802 E.g. to join 3 inputs (with properly set channel layouts)
804 ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
807 To build a 5.1 output from 6 single-channel streams:
809 ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
810 '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'
815 Convert the audio sample format, sample rate and channel layout. This filter is
816 not meant to be used directly.
818 @c man end AUDIO FILTERS
820 @chapter Audio Sources
821 @c man begin AUDIO SOURCES
823 Below is a description of the currently available audio sources.
827 Buffer audio frames, and make them available to the filter chain.
829 This source is mainly intended for a programmatic use, in particular
830 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
832 It accepts the following mandatory parameters:
833 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}
838 The sample rate of the incoming audio buffers.
841 The sample format of the incoming audio buffers.
842 Either a sample format name or its corresponging integer representation from
843 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
846 The channel layout of the incoming audio buffers.
847 Either a channel layout name from channel_layout_map in
848 @file{libavutil/audioconvert.c} or its corresponding integer representation
849 from the AV_CH_LAYOUT_* macros in @file{libavutil/audioconvert.h}
855 abuffer=44100:s16p:stereo
858 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
859 Since the sample format with name "s16p" corresponds to the number
860 6 and the "stereo" channel layout corresponds to the value 0x3, this is
868 Generate an audio signal specified by an expression.
870 This source accepts in input one or more expressions (one for each
871 channel), which are evaluated and used to generate a corresponding
874 It accepts the syntax: @var{exprs}[::@var{options}].
875 @var{exprs} is a list of expressions separated by ":", one for each
876 separate channel. In case the @var{channel_layout} is not
877 specified, the selected channel layout depends on the number of
878 provided expressions.
880 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
883 The description of the accepted options follows.
887 @item channel_layout, c
888 Set the channel layout. The number of channels in the specified layout
889 must be equal to the number of specified expressions.
892 Set the minimum duration of the sourced audio. See the function
893 @code{av_parse_time()} for the accepted format.
894 Note that the resulting duration may be greater than the specified
895 duration, as the generated audio is always cut at the end of a
898 If not specified, or the expressed duration is negative, the audio is
899 supposed to be generated forever.
902 Set the number of samples per channel per each output frame,
906 Specify the sample rate, default to 44100.
909 Each expression in @var{exprs} can contain the following constants:
913 number of the evaluated sample, starting from 0
916 time of the evaluated sample expressed in seconds, starting from 0
935 Generate a sin signal with frequency of 440 Hz, set sample rate to
938 aevalsrc="sin(440*2*PI*t)::s=8000"
942 Generate a two channels signal, specify the channel layout (Front
943 Center + Back Center) explicitly:
945 aevalsrc="sin(420*2*PI*t):cos(430*2*PI*t)::c=FC|BC"
949 Generate white noise:
951 aevalsrc="-2+random(0)"
955 Generate an amplitude modulated signal:
957 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
961 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
963 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
970 Null audio source, return unprocessed audio frames. It is mainly useful
971 as a template and to be employed in analysis / debugging tools, or as
972 the source for filters which ignore the input data (for example the sox
975 It accepts an optional sequence of @var{key}=@var{value} pairs,
978 The description of the accepted options follows.
983 Specify the sample rate, and defaults to 44100.
985 @item channel_layout, cl
987 Specify the channel layout, and can be either an integer or a string
988 representing a channel layout. The default value of @var{channel_layout}
991 Check the channel_layout_map definition in
992 @file{libavcodec/audioconvert.c} for the mapping between strings and
993 channel layout values.
996 Set the number of samples per requested frames.
1000 Follow some examples:
1002 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
1003 anullsrc=r=48000:cl=4
1006 anullsrc=r=48000:cl=mono
1010 Buffer audio frames, and make them available to the filter chain.
1012 This source is not intended to be part of user-supplied graph descriptions but
1013 for insertion by calling programs through the interface defined in
1014 @file{libavfilter/buffersrc.h}.
1016 It accepts the following named parameters:
1020 Timebase which will be used for timestamps of submitted frames. It must be
1021 either a floating-point number or in @var{numerator}/@var{denominator} form.
1027 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
1029 @item channel_layout
1030 Channel layout of the audio data, in the form that can be accepted by
1031 @code{av_get_channel_layout()}.
1034 All the parameters need to be explicitly defined.
1038 Synthesize a voice utterance using the libflite library.
1040 To enable compilation of this filter you need to configure FFmpeg with
1041 @code{--enable-libflite}.
1043 Note that the flite library is not thread-safe.
1045 The source accepts parameters as a list of @var{key}=@var{value} pairs,
1048 The description of the accepted parameters follows.
1053 If set to 1, list the names of the available voices and exit
1054 immediately. Default value is 0.
1057 Set the maximum number of samples per frame. Default value is 512.
1060 Set the filename containing the text to speak.
1063 Set the text to speak.
1066 Set the voice to use for the speech synthesis. Default value is
1067 @code{kal}. See also the @var{list_voices} option.
1074 Read from file @file{speech.txt}, and synthetize the text using the
1075 standard flite voice:
1077 flite=textfile=speech.txt
1081 Read the specified text selecting the @code{slt} voice:
1083 flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
1087 Make @file{ffplay} speech the specified text, using @code{flite} and
1088 the @code{lavfi} device:
1090 ffplay -f lavfi flite='No more be grieved for which that thou hast done.'
1094 For more information about libflite, check:
1095 @url{http://www.speech.cs.cmu.edu/flite/}
1097 @c man end AUDIO SOURCES
1099 @chapter Audio Sinks
1100 @c man begin AUDIO SINKS
1102 Below is a description of the currently available audio sinks.
1104 @section abuffersink
1106 Buffer audio frames, and make them available to the end of filter chain.
1108 This sink is mainly intended for programmatic use, in particular
1109 through the interface defined in @file{libavfilter/buffersink.h}.
1111 It requires a pointer to an AVABufferSinkContext structure, which
1112 defines the incoming buffers' formats, to be passed as the opaque
1113 parameter to @code{avfilter_init_filter} for initialization.
1117 Null audio sink, do absolutely nothing with the input audio. It is
1118 mainly useful as a template and to be employed in analysis / debugging
1121 @section abuffersink
1122 This sink is intended for programmatic use. Frames that arrive on this sink can
1123 be retrieved by the calling program using the interface defined in
1124 @file{libavfilter/buffersink.h}.
1126 This filter accepts no parameters.
1128 @c man end AUDIO SINKS
1130 @chapter Video Filters
1131 @c man begin VIDEO FILTERS
1133 When you configure your FFmpeg build, you can disable any of the
1134 existing filters using @code{--disable-filters}.
1135 The configure output will show the video filters included in your
1138 Below is a description of the currently available video filters.
1140 @section alphaextract
1142 Extract the alpha component from the input as a grayscale video. This
1143 is especially useful with the @var{alphamerge} filter.
1147 Add or replace the alpha component of the primary input with the
1148 grayscale value of a second input. This is intended for use with
1149 @var{alphaextract} to allow the transmission or storage of frame
1150 sequences that have alpha in a format that doesn't support an alpha
1153 For example, to reconstruct full frames from a normal YUV-encoded video
1154 and a separate video created with @var{alphaextract}, you might use:
1156 movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
1159 Since this filter is designed for reconstruction, it operates on frame
1160 sequences without considering timestamps, and terminates when either
1161 input reaches end of stream. This will cause problems if your encoding
1162 pipeline drops frames. If you're trying to apply an image as an
1163 overlay to a video stream, consider the @var{overlay} filter instead.
1167 Draw ASS (Advanced Substation Alpha) subtitles on top of input video
1168 using the libass library.
1170 To enable compilation of this filter you need to configure FFmpeg with
1171 @code{--enable-libass}.
1173 This filter accepts the syntax: @var{ass_filename}[:@var{options}],
1174 where @var{ass_filename} is the filename of the ASS file to read, and
1175 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1178 A description of the accepted options follows.
1182 Specifies the size of the original video, the video for which the ASS file
1183 was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
1184 necessary to correctly scale the fonts if the aspect ratio has been changed.
1187 For example, to render the file @file{sub.ass} on top of the input
1188 video, use the command:
1195 Compute the bounding box for the non-black pixels in the input frame
1198 This filter computes the bounding box containing all the pixels with a
1199 luminance value greater than the minimum allowed value.
1200 The parameters describing the bounding box are printed on the filter
1203 @section blackdetect
1205 Detect video intervals that are (almost) completely black. Can be
1206 useful to detect chapter transitions, commercials, or invalid
1207 recordings. Output lines contains the time for the start, end and
1208 duration of the detected black interval expressed in seconds.
1210 In order to display the output lines, you need to set the loglevel at
1211 least to the AV_LOG_INFO value.
1213 This filter accepts a list of options in the form of
1214 @var{key}=@var{value} pairs separated by ":". A description of the
1215 accepted options follows.
1218 @item black_min_duration, d
1219 Set the minimum detected black duration expressed in seconds. It must
1220 be a non-negative floating point number.
1222 Default value is 2.0.
1224 @item picture_black_ratio_th, pic_th
1225 Set the threshold for considering a picture "black".
1226 Express the minimum value for the ratio:
1228 @var{nb_black_pixels} / @var{nb_pixels}
1231 for which a picture is considered black.
1232 Default value is 0.98.
1234 @item pixel_black_th, pix_th
1235 Set the threshold for considering a pixel "black".
1237 The threshold expresses the maximum pixel luminance value for which a
1238 pixel is considered "black". The provided value is scaled according to
1239 the following equation:
1241 @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size}
1244 @var{luminance_range_size} and @var{luminance_minimum_value} depend on
1245 the input video format, the range is [0-255] for YUV full-range
1246 formats and [16-235] for YUV non full-range formats.
1248 Default value is 0.10.
1251 The following example sets the maximum pixel threshold to the minimum
1252 value, and detects only black intervals of 2 or more seconds:
1254 blackdetect=d=2:pix_th=0.00
1259 Detect frames that are (almost) completely black. Can be useful to
1260 detect chapter transitions or commercials. Output lines consist of
1261 the frame number of the detected frame, the percentage of blackness,
1262 the position in the file if known or -1 and the timestamp in seconds.
1264 In order to display the output lines, you need to set the loglevel at
1265 least to the AV_LOG_INFO value.
1267 The filter accepts the syntax:
1269 blackframe[=@var{amount}:[@var{threshold}]]
1272 @var{amount} is the percentage of the pixels that have to be below the
1273 threshold, and defaults to 98.
1275 @var{threshold} is the threshold below which a pixel value is
1276 considered black, and defaults to 32.
1280 Apply boxblur algorithm to the input video.
1282 This filter accepts the parameters:
1283 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
1285 Chroma and alpha parameters are optional, if not specified they default
1286 to the corresponding values set for @var{luma_radius} and
1289 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
1290 the radius in pixels of the box used for blurring the corresponding
1291 input plane. They are expressions, and can contain the following
1295 the input width and height in pixels
1298 the input chroma image width and height in pixels
1301 horizontal and vertical chroma subsample values. For example for the
1302 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1305 The radius must be a non-negative number, and must not be greater than
1306 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
1307 and of @code{min(cw,ch)/2} for the chroma planes.
1309 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
1310 how many times the boxblur filter is applied to the corresponding
1313 Some examples follow:
1318 Apply a boxblur filter with luma, chroma, and alpha radius
1325 Set luma radius to 2, alpha and chroma radius to 0
1331 Set luma and chroma radius to a fraction of the video dimension
1333 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
1338 @section colormatrix
1340 The colormatrix filter allows conversion between any of the following color
1341 space: BT.709 (@var{bt709}), BT.601 (@var{bt601}), SMPTE-240M (@var{smpte240m})
1342 and FCC (@var{fcc}).
1344 The syntax of the parameters is @var{source}:@var{destination}:
1347 colormatrix=bt601:smpte240m
1352 Copy the input source unchanged to the output. Mainly useful for
1357 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}:@var{keep_aspect}
1359 The @var{keep_aspect} parameter is optional, if specified and set to a
1360 non-zero value will force the output display aspect ratio to be the
1361 same of the input, by changing the output sample aspect ratio.
1363 The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are
1364 expressions containing the following constants:
1368 the computed values for @var{x} and @var{y}. They are evaluated for
1372 the input width and height
1375 same as @var{in_w} and @var{in_h}
1378 the output (cropped) width and height
1381 same as @var{out_w} and @var{out_h}
1384 same as @var{iw} / @var{ih}
1387 input sample aspect ratio
1390 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1393 horizontal and vertical chroma subsample values. For example for the
1394 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1397 the number of input frame, starting from 0
1400 the position in the file of the input frame, NAN if unknown
1403 timestamp expressed in seconds, NAN if the input timestamp is unknown
1407 The @var{out_w} and @var{out_h} parameters specify the expressions for
1408 the width and height of the output (cropped) video. They are
1409 evaluated just at the configuration of the filter.
1411 The default value of @var{out_w} is "in_w", and the default value of
1412 @var{out_h} is "in_h".
1414 The expression for @var{out_w} may depend on the value of @var{out_h},
1415 and the expression for @var{out_h} may depend on @var{out_w}, but they
1416 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
1417 evaluated after @var{out_w} and @var{out_h}.
1419 The @var{x} and @var{y} parameters specify the expressions for the
1420 position of the top-left corner of the output (non-cropped) area. They
1421 are evaluated for each frame. If the evaluated value is not valid, it
1422 is approximated to the nearest valid value.
1424 The default value of @var{x} is "(in_w-out_w)/2", and the default
1425 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
1426 the center of the input image.
1428 The expression for @var{x} may depend on @var{y}, and the expression
1429 for @var{y} may depend on @var{x}.
1431 Follow some examples:
1433 # crop the central input area with size 100x100
1436 # crop the central input area with size 2/3 of the input video
1437 "crop=2/3*in_w:2/3*in_h"
1439 # crop the input video central square
1442 # delimit the rectangle with the top-left corner placed at position
1443 # 100:100 and the right-bottom corner corresponding to the right-bottom
1444 # corner of the input image.
1445 crop=in_w-100:in_h-100:100:100
1447 # crop 10 pixels from the left and right borders, and 20 pixels from
1448 # the top and bottom borders
1449 "crop=in_w-2*10:in_h-2*20"
1451 # keep only the bottom right quarter of the input image
1452 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
1454 # crop height for getting Greek harmony
1455 "crop=in_w:1/PHI*in_w"
1458 "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)"
1460 # erratic camera effect depending on timestamp
1461 "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)"
1463 # set x depending on the value of y
1464 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
1469 Auto-detect crop size.
1471 Calculate necessary cropping parameters and prints the recommended
1472 parameters through the logging system. The detected dimensions
1473 correspond to the non-black area of the input video.
1475 It accepts the syntax:
1477 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
1483 Threshold, which can be optionally specified from nothing (0) to
1484 everything (255), defaults to 24.
1487 Value which the width/height should be divisible by, defaults to
1488 16. The offset is automatically adjusted to center the video. Use 2 to
1489 get only even dimensions (needed for 4:2:2 video). 16 is best when
1490 encoding to most video codecs.
1493 Counter that determines after how many frames cropdetect will reset
1494 the previously detected largest video area and start over to detect
1495 the current optimal crop area. Defaults to 0.
1497 This can be useful when channel logos distort the video area. 0
1498 indicates never reset and return the largest area encountered during
1504 Suppress a TV station logo by a simple interpolation of the surrounding
1505 pixels. Just set a rectangle covering the logo and watch it disappear
1506 (and sometimes something even uglier appear - your mileage may vary).
1508 The filter accepts parameters as a string of the form
1509 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
1510 @var{key}=@var{value} pairs, separated by ":".
1512 The description of the accepted parameters follows.
1517 Specify the top left corner coordinates of the logo. They must be
1521 Specify the width and height of the logo to clear. They must be
1525 Specify the thickness of the fuzzy edge of the rectangle (added to
1526 @var{w} and @var{h}). The default value is 4.
1529 When set to 1, a green rectangle is drawn on the screen to simplify
1530 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1531 @var{band} is set to 4. The default value is 0.
1535 Some examples follow.
1540 Set a rectangle covering the area with top left corner coordinates 0,0
1541 and size 100x77, setting a band of size 10:
1543 delogo=0:0:100:77:10
1547 As the previous example, but use named options:
1549 delogo=x=0:y=0:w=100:h=77:band=10
1556 Attempt to fix small changes in horizontal and/or vertical shift. This
1557 filter helps remove camera shake from hand-holding a camera, bumping a
1558 tripod, moving on a vehicle, etc.
1560 The filter accepts parameters as a string of the form
1561 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
1563 A description of the accepted parameters follows.
1568 Specify a rectangular area where to limit the search for motion
1570 If desired the search for motion vectors can be limited to a
1571 rectangular area of the frame defined by its top left corner, width
1572 and height. These parameters have the same meaning as the drawbox
1573 filter which can be used to visualise the position of the bounding
1576 This is useful when simultaneous movement of subjects within the frame
1577 might be confused for camera motion by the motion vector search.
1579 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
1580 then the full frame is used. This allows later options to be set
1581 without specifying the bounding box for the motion vector search.
1583 Default - search the whole frame.
1586 Specify the maximum extent of movement in x and y directions in the
1587 range 0-64 pixels. Default 16.
1590 Specify how to generate pixels to fill blanks at the edge of the
1591 frame. An integer from 0 to 3 as follows:
1594 Fill zeroes at blank locations
1596 Original image at blank locations
1598 Extruded edge value at blank locations
1600 Mirrored edge at blank locations
1603 The default setting is mirror edge at blank locations.
1606 Specify the blocksize to use for motion search. Range 4-128 pixels,
1610 Specify the contrast threshold for blocks. Only blocks with more than
1611 the specified contrast (difference between darkest and lightest
1612 pixels) will be considered. Range 1-255, default 125.
1615 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
1616 search. Default - exhaustive search.
1619 If set then a detailed log of the motion search is written to the
1626 Draw a colored box on the input image.
1628 It accepts the syntax:
1630 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
1636 Specify the top left corner coordinates of the box. Default to 0.
1639 Specify the width and height of the box, if 0 they are interpreted as
1640 the input width and height. Default to 0.
1643 Specify the color of the box to write, it can be the name of a color
1644 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1647 Follow some examples:
1649 # draw a black box around the edge of the input image
1652 # draw a box with color red and an opacity of 50%
1653 drawbox=10:20:200:60:red@@0.5"
1658 Draw text string or text from specified file on top of video using the
1659 libfreetype library.
1661 To enable compilation of this filter you need to configure FFmpeg with
1662 @code{--enable-libfreetype}.
1664 The filter also recognizes strftime() sequences in the provided text
1665 and expands them accordingly. Check the documentation of strftime().
1667 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
1670 The description of the accepted parameters follows.
1675 Used to draw a box around text using background color.
1676 Value should be either 1 (enable) or 0 (disable).
1677 The default value of @var{box} is 0.
1680 The color to be used for drawing box around text.
1681 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1682 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1683 The default value of @var{boxcolor} is "white".
1686 Set an expression which specifies if the text should be drawn. If the
1687 expression evaluates to 0, the text is not drawn. This is useful for
1688 specifying that the text should be drawn only when specific conditions
1691 Default value is "1".
1693 See below for the list of accepted constants and functions.
1696 If true, check and fix text coords to avoid clipping.
1699 The color to be used for drawing fonts.
1700 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1701 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1702 The default value of @var{fontcolor} is "black".
1705 The font file to be used for drawing text. Path must be included.
1706 This parameter is mandatory.
1709 The font size to be used for drawing text.
1710 The default value of @var{fontsize} is 16.
1713 Flags to be used for loading the fonts.
1715 The flags map the corresponding flags supported by libfreetype, and are
1716 a combination of the following values:
1723 @item vertical_layout
1724 @item force_autohint
1727 @item ignore_global_advance_width
1729 @item ignore_transform
1736 Default value is "render".
1738 For more information consult the documentation for the FT_LOAD_*
1742 The color to be used for drawing a shadow behind the drawn text. It
1743 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1744 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1745 The default value of @var{shadowcolor} is "black".
1747 @item shadowx, shadowy
1748 The x and y offsets for the text shadow position with respect to the
1749 position of the text. They can be either positive or negative
1750 values. Default value for both is "0".
1753 The size in number of spaces to use for rendering the tab.
1757 Set the initial timecode representation in "hh:mm:ss[:;.]ff"
1758 format. It can be used with or without text parameter. @var{timecode_rate}
1759 option must be specified.
1761 @item timecode_rate, rate, r
1762 Set the timecode frame rate (timecode only).
1765 The text string to be drawn. The text must be a sequence of UTF-8
1767 This parameter is mandatory if no file is specified with the parameter
1771 A text file containing text to be drawn. The text must be a sequence
1772 of UTF-8 encoded characters.
1774 This parameter is mandatory if no text string is specified with the
1775 parameter @var{text}.
1777 If both @var{text} and @var{textfile} are specified, an error is thrown.
1780 The expressions which specify the offsets where text will be drawn
1781 within the video frame. They are relative to the top/left border of the
1784 The default value of @var{x} and @var{y} is "0".
1786 See below for the list of accepted constants and functions.
1789 The parameters for @var{x} and @var{y} are expressions containing the
1790 following constants and functions:
1794 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
1797 horizontal and vertical chroma subsample values. For example for the
1798 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1801 the height of each text line
1809 @item max_glyph_a, ascent
1810 the maximum distance from the baseline to the highest/upper grid
1811 coordinate used to place a glyph outline point, for all the rendered
1813 It is a positive value, due to the grid's orientation with the Y axis
1816 @item max_glyph_d, descent
1817 the maximum distance from the baseline to the lowest grid coordinate
1818 used to place a glyph outline point, for all the rendered glyphs.
1819 This is a negative value, due to the grid's orientation, with the Y axis
1823 maximum glyph height, that is the maximum height for all the glyphs
1824 contained in the rendered text, it is equivalent to @var{ascent} -
1828 maximum glyph width, that is the maximum width for all the glyphs
1829 contained in the rendered text
1832 the number of input frame, starting from 0
1834 @item rand(min, max)
1835 return a random number included between @var{min} and @var{max}
1838 input sample aspect ratio
1841 timestamp expressed in seconds, NAN if the input timestamp is unknown
1844 the height of the rendered text
1847 the width of the rendered text
1850 the x and y offset coordinates where the text is drawn.
1852 These parameters allow the @var{x} and @var{y} expressions to refer
1853 each other, so you can for example specify @code{y=x/dar}.
1856 If libavfilter was built with @code{--enable-fontconfig}, then
1857 @option{fontfile} can be a fontconfig pattern or omitted.
1859 Some examples follow.
1864 Draw "Test Text" with font FreeSerif, using the default values for the
1865 optional parameters.
1868 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1872 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
1873 and y=50 (counting from the top-left corner of the screen), text is
1874 yellow with a red box around it. Both the text and the box have an
1878 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1879 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1882 Note that the double quotes are not necessary if spaces are not used
1883 within the parameter list.
1886 Show the text at the center of the video frame:
1888 drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
1892 Show a text line sliding from right to left in the last row of the video
1893 frame. The file @file{LONG_LINE} is assumed to contain a single line
1896 drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
1900 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
1902 drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
1906 Draw a single green letter "g", at the center of the input video.
1907 The glyph baseline is placed at half screen height.
1909 drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
1913 Show text for 1 second every 3 seconds:
1915 drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:draw=lt(mod(t\\,3)\\,1):text='blink'"
1919 Use fontconfig to set the font. Note that the colons need to be escaped.
1921 drawtext='fontfile=Linux Libertine O-40\\:style=Semibold:text=FFmpeg'
1926 For more information about libfreetype, check:
1927 @url{http://www.freetype.org/}.
1929 For more information about fontconfig, check:
1930 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.
1934 Apply fade-in/out effect to input video.
1936 It accepts the parameters:
1937 @var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}]
1939 @var{type} specifies if the effect type, can be either "in" for
1940 fade-in, or "out" for a fade-out effect.
1942 @var{start_frame} specifies the number of the start frame for starting
1943 to apply the fade effect.
1945 @var{nb_frames} specifies the number of frames for which the fade
1946 effect has to last. At the end of the fade-in effect the output video
1947 will have the same intensity as the input video, at the end of the
1948 fade-out transition the output video will be completely black.
1950 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1951 separated by ":". The description of the accepted options follows.
1958 @item start_frame, s
1959 See @var{start_frame}.
1962 See @var{nb_frames}.
1965 If set to 1, fade only alpha channel, if one exists on the input.
1969 A few usage examples follow, usable too as test scenarios.
1971 # fade in first 30 frames of video
1974 # fade out last 45 frames of a 200-frame video
1977 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
1978 fade=in:0:25, fade=out:975:25
1980 # make first 5 frames black, then fade in from frame 5-24
1983 # fade in alpha over first 25 frames of video
1984 fade=in:0:25:alpha=1
1989 Transform the field order of the input video.
1991 It accepts one parameter which specifies the required field order that
1992 the input interlaced video will be transformed to. The parameter can
1993 assume one of the following values:
1997 output bottom field first
1999 output top field first
2002 Default value is "tff".
2004 Transformation is achieved by shifting the picture content up or down
2005 by one line, and filling the remaining line with appropriate picture content.
2006 This method is consistent with most broadcast field order converters.
2008 If the input video is not flagged as being interlaced, or it is already
2009 flagged as being of the required output field order then this filter does
2010 not alter the incoming video.
2012 This filter is very useful when converting to or from PAL DV material,
2013 which is bottom field first.
2017 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
2022 Buffer input images and send them when they are requested.
2024 This filter is mainly useful when auto-inserted by the libavfilter
2027 The filter does not take parameters.
2031 Convert the input video to one of the specified pixel formats.
2032 Libavfilter will try to pick one that is supported for the input to
2035 The filter accepts a list of pixel format names, separated by ":",
2036 for example "yuv420p:monow:rgb24".
2038 Some examples follow:
2040 # convert the input video to the format "yuv420p"
2043 # convert the input video to any of the formats in the list
2044 format=yuv420p:yuv444p:yuv410p
2049 Convert the video to specified constant framerate by duplicating or dropping
2050 frames as necessary.
2052 This filter accepts the following named parameters:
2056 Desired output framerate.
2063 Apply a frei0r effect to the input video.
2065 To enable compilation of this filter you need to install the frei0r
2066 header and configure FFmpeg with @code{--enable-frei0r}.
2068 The filter supports the syntax:
2070 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
2073 @var{filter_name} is the name to the frei0r effect to load. If the
2074 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
2075 is searched in each one of the directories specified by the colon
2076 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
2077 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
2078 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
2080 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
2081 for the frei0r effect.
2083 A frei0r effect parameter can be a boolean (whose values are specified
2084 with "y" and "n"), a double, a color (specified by the syntax
2085 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
2086 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
2087 description), a position (specified by the syntax @var{X}/@var{Y},
2088 @var{X} and @var{Y} being float numbers) and a string.
2090 The number and kind of parameters depend on the loaded effect. If an
2091 effect parameter is not specified the default value is set.
2093 Some examples follow:
2097 Apply the distort0r effect, set the first two double parameters:
2099 frei0r=distort0r:0.5:0.01
2103 Apply the colordistance effect, takes a color as first parameter:
2105 frei0r=colordistance:0.2/0.3/0.4
2106 frei0r=colordistance:violet
2107 frei0r=colordistance:0x112233
2111 Apply the perspective effect, specify the top left and top right image
2114 frei0r=perspective:0.2/0.2:0.8/0.2
2118 For more information see:
2119 @url{http://frei0r.dyne.org}
2123 Fix the banding artifacts that are sometimes introduced into nearly flat
2124 regions by truncation to 8bit color depth.
2125 Interpolate the gradients that should go where the bands are, and
2128 This filter is designed for playback only. Do not use it prior to
2129 lossy compression, because compression tends to lose the dither and
2130 bring back the bands.
2132 The filter takes two optional parameters, separated by ':':
2133 @var{strength}:@var{radius}
2135 @var{strength} is the maximum amount by which the filter will change
2136 any one pixel. Also the threshold for detecting nearly flat
2137 regions. Acceptable values range from .51 to 255, default value is
2138 1.2, out-of-range values will be clipped to the valid range.
2140 @var{radius} is the neighborhood to fit the gradient to. A larger
2141 radius makes for smoother gradients, but also prevents the filter from
2142 modifying the pixels near detailed regions. Acceptable values are
2143 8-32, default value is 16, out-of-range values will be clipped to the
2147 # default parameters
2156 Flip the input video horizontally.
2158 For example to horizontally flip the input video with @command{ffmpeg}:
2160 ffmpeg -i in.avi -vf "hflip" out.avi
2165 High precision/quality 3d denoise filter. This filter aims to reduce
2166 image noise producing smooth images and making still images really
2167 still. It should enhance compressibility.
2169 It accepts the following optional parameters:
2170 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
2174 a non-negative float number which specifies spatial luma strength,
2177 @item chroma_spatial
2178 a non-negative float number which specifies spatial chroma strength,
2179 defaults to 3.0*@var{luma_spatial}/4.0
2182 a float number which specifies luma temporal strength, defaults to
2183 6.0*@var{luma_spatial}/4.0
2186 a float number which specifies chroma temporal strength, defaults to
2187 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
2192 Interlaceing detect filter. This filter tries to detect if the input is
2193 interlaced or progressive. Top or bottom field first.
2195 @section lut, lutrgb, lutyuv
2197 Compute a look-up table for binding each pixel component input value
2198 to an output value, and apply it to input video.
2200 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
2201 to an RGB input video.
2203 These filters accept in input a ":"-separated list of options, which
2204 specify the expressions used for computing the lookup table for the
2205 corresponding pixel component values.
2207 The @var{lut} filter requires either YUV or RGB pixel formats in
2208 input, and accepts the options:
2211 first pixel component
2213 second pixel component
2215 third pixel component
2217 fourth pixel component, corresponds to the alpha component
2220 The exact component associated to each option depends on the format in
2223 The @var{lutrgb} filter requires RGB pixel formats in input, and
2224 accepts the options:
2236 The @var{lutyuv} filter requires YUV pixel formats in input, and
2237 accepts the options:
2240 Y/luminance component
2249 The expressions can contain the following constants and functions:
2253 the input width and height
2256 input value for the pixel component
2259 the input value clipped in the @var{minval}-@var{maxval} range
2262 maximum value for the pixel component
2265 minimum value for the pixel component
2268 the negated value for the pixel component value clipped in the
2269 @var{minval}-@var{maxval} range , it corresponds to the expression
2270 "maxval-clipval+minval"
2273 the computed value in @var{val} clipped in the
2274 @var{minval}-@var{maxval} range
2276 @item gammaval(gamma)
2277 the computed gamma correction value of the pixel component value
2278 clipped in the @var{minval}-@var{maxval} range, corresponds to the
2280 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
2284 All expressions default to "val".
2286 Some examples follow:
2288 # negate input video
2289 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
2290 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
2292 # the above is the same as
2293 lutrgb="r=negval:g=negval:b=negval"
2294 lutyuv="y=negval:u=negval:v=negval"
2299 # remove chroma components, turns the video into a graytone image
2300 lutyuv="u=128:v=128"
2302 # apply a luma burning effect
2305 # remove green and blue components
2308 # set a constant alpha channel value on input
2309 format=rgba,lutrgb=a="maxval-minval/2"
2311 # correct luminance gamma by a 0.5 factor
2312 lutyuv=y=gammaval(0.5)
2317 Apply an MPlayer filter to the input video.
2319 This filter provides a wrapper around most of the filters of
2322 This wrapper is considered experimental. Some of the wrapped filters
2323 may not work properly and we may drop support for them, as they will
2324 be implemented natively into FFmpeg. Thus you should avoid
2325 depending on them when writing portable scripts.
2327 The filters accepts the parameters:
2328 @var{filter_name}[:=]@var{filter_params}
2330 @var{filter_name} is the name of a supported MPlayer filter,
2331 @var{filter_params} is a string containing the parameters accepted by
2334 The list of the currently supported filters follows:
2383 The parameter syntax and behavior for the listed filters are the same
2384 of the corresponding MPlayer filters. For detailed instructions check
2385 the "VIDEO FILTERS" section in the MPlayer manual.
2387 Some examples follow:
2389 # adjust gamma, brightness, contrast
2392 # tweak hue and saturation
2396 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
2402 This filter accepts an integer in input, if non-zero it negates the
2403 alpha component (if available). The default value in input is 0.
2407 Force libavfilter not to use any of the specified pixel formats for the
2408 input to the next filter.
2410 The filter accepts a list of pixel format names, separated by ":",
2411 for example "yuv420p:monow:rgb24".
2413 Some examples follow:
2415 # force libavfilter to use a format different from "yuv420p" for the
2416 # input to the vflip filter
2417 noformat=yuv420p,vflip
2419 # convert the input video to any of the formats not contained in the list
2420 noformat=yuv420p:yuv444p:yuv410p
2425 Pass the video source unchanged to the output.
2429 Apply video transform using libopencv.
2431 To enable this filter install libopencv library and headers and
2432 configure FFmpeg with @code{--enable-libopencv}.
2434 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
2436 @var{filter_name} is the name of the libopencv filter to apply.
2438 @var{filter_params} specifies the parameters to pass to the libopencv
2439 filter. If not specified the default values are assumed.
2441 Refer to the official libopencv documentation for more precise
2443 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
2445 Follows the list of supported libopencv filters.
2450 Dilate an image by using a specific structuring element.
2451 This filter corresponds to the libopencv function @code{cvDilate}.
2453 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
2455 @var{struct_el} represents a structuring element, and has the syntax:
2456 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
2458 @var{cols} and @var{rows} represent the number of columns and rows of
2459 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
2460 point, and @var{shape} the shape for the structuring element, and
2461 can be one of the values "rect", "cross", "ellipse", "custom".
2463 If the value for @var{shape} is "custom", it must be followed by a
2464 string of the form "=@var{filename}". The file with name
2465 @var{filename} is assumed to represent a binary image, with each
2466 printable character corresponding to a bright pixel. When a custom
2467 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
2468 or columns and rows of the read file are assumed instead.
2470 The default value for @var{struct_el} is "3x3+0x0/rect".
2472 @var{nb_iterations} specifies the number of times the transform is
2473 applied to the image, and defaults to 1.
2475 Follow some example:
2477 # use the default values
2480 # dilate using a structuring element with a 5x5 cross, iterate two times
2481 ocv=dilate=5x5+2x2/cross:2
2483 # read the shape from the file diamond.shape, iterate two times
2484 # the file diamond.shape may contain a pattern of characters like this:
2490 # the specified cols and rows are ignored (but not the anchor point coordinates)
2491 ocv=0x0+2x2/custom=diamond.shape:2
2496 Erode an image by using a specific structuring element.
2497 This filter corresponds to the libopencv function @code{cvErode}.
2499 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
2500 with the same syntax and semantics as the @ref{dilate} filter.
2504 Smooth the input video.
2506 The filter takes the following parameters:
2507 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
2509 @var{type} is the type of smooth filter to apply, and can be one of
2510 the following values: "blur", "blur_no_scale", "median", "gaussian",
2511 "bilateral". The default value is "gaussian".
2513 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
2514 parameters whose meanings depend on smooth type. @var{param1} and
2515 @var{param2} accept integer positive values or 0, @var{param3} and
2516 @var{param4} accept float values.
2518 The default value for @var{param1} is 3, the default value for the
2519 other parameters is 0.
2521 These parameters correspond to the parameters assigned to the
2522 libopencv function @code{cvSmooth}.
2527 Overlay one video on top of another.
2529 It takes two inputs and one output, the first input is the "main"
2530 video on which the second input is overlayed.
2532 It accepts the parameters: @var{x}:@var{y}[:@var{options}].
2534 @var{x} is the x coordinate of the overlayed video on the main video,
2535 @var{y} is the y coordinate. @var{x} and @var{y} are expressions containing
2536 the following parameters:
2539 @item main_w, main_h
2540 main input width and height
2543 same as @var{main_w} and @var{main_h}
2545 @item overlay_w, overlay_h
2546 overlay input width and height
2549 same as @var{overlay_w} and @var{overlay_h}
2552 @var{options} is an optional list of @var{key}=@var{value} pairs,
2555 The description of the accepted options follows.
2559 If set to 1, force the filter to accept inputs in the RGB
2560 color space. Default value is 0.
2563 Be aware that frames are taken from each input video in timestamp
2564 order, hence, if their initial timestamps differ, it is a a good idea
2565 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
2566 have them begin in the same zero timestamp, as it does the example for
2567 the @var{movie} filter.
2569 Follow some examples:
2571 # draw the overlay at 10 pixels from the bottom right
2572 # corner of the main video.
2573 overlay=main_w-overlay_w-10:main_h-overlay_h-10
2575 # insert a transparent PNG logo in the bottom left corner of the input
2576 ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
2578 # insert 2 different transparent PNG logos (second logo on bottom
2580 ffmpeg -i input -i logo1 -i logo2 -filter_complex
2581 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
2583 # add a transparent color layer on top of the main video,
2584 # WxH specifies the size of the main input to the overlay filter
2585 color=red@.3:WxH [over]; [in][over] overlay [out]
2587 # play an original video and a filtered version (here with the deshake filter)
2589 ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
2591 # the previous example is the same as:
2592 ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
2595 You can chain together more overlays but the efficiency of such
2596 approach is yet to be tested.
2600 Add paddings to the input image, and places the original input at the
2601 given coordinates @var{x}, @var{y}.
2603 It accepts the following parameters:
2604 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
2606 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
2607 expressions containing the following constants:
2611 the input video width and height
2614 same as @var{in_w} and @var{in_h}
2617 the output width and height, that is the size of the padded area as
2618 specified by the @var{width} and @var{height} expressions
2621 same as @var{out_w} and @var{out_h}
2624 x and y offsets as specified by the @var{x} and @var{y}
2625 expressions, or NAN if not yet specified
2628 same as @var{iw} / @var{ih}
2631 input sample aspect ratio
2634 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2637 horizontal and vertical chroma subsample values. For example for the
2638 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2641 Follows the description of the accepted parameters.
2646 Specify the size of the output image with the paddings added. If the
2647 value for @var{width} or @var{height} is 0, the corresponding input size
2648 is used for the output.
2650 The @var{width} expression can reference the value set by the
2651 @var{height} expression, and vice versa.
2653 The default value of @var{width} and @var{height} is 0.
2657 Specify the offsets where to place the input image in the padded area
2658 with respect to the top/left border of the output image.
2660 The @var{x} expression can reference the value set by the @var{y}
2661 expression, and vice versa.
2663 The default value of @var{x} and @var{y} is 0.
2667 Specify the color of the padded area, it can be the name of a color
2668 (case insensitive match) or a 0xRRGGBB[AA] sequence.
2670 The default value of @var{color} is "black".
2674 Some examples follow:
2677 # Add paddings with color "violet" to the input video. Output video
2678 # size is 640x480, the top-left corner of the input video is placed at
2680 pad=640:480:0:40:violet
2682 # pad the input to get an output with dimensions increased bt 3/2,
2683 # and put the input video at the center of the padded area
2684 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
2686 # pad the input to get a squared output with size equal to the maximum
2687 # value between the input width and height, and put the input video at
2688 # the center of the padded area
2689 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
2691 # pad the input to get a final w/h ratio of 16:9
2692 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
2694 # for anamorphic video, in order to set the output display aspect ratio,
2695 # it is necessary to use sar in the expression, according to the relation:
2696 # (ih * X / ih) * sar = output_dar
2697 # X = output_dar / sar
2698 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
2700 # double output size and put the input video in the bottom-right
2701 # corner of the output padded area
2702 pad="2*iw:2*ih:ow-iw:oh-ih"
2705 @section pixdesctest
2707 Pixel format descriptor test filter, mainly useful for internal
2708 testing. The output video should be equal to the input video.
2712 format=monow, pixdesctest
2715 can be used to test the monowhite pixel format descriptor definition.
2719 Suppress a TV station logo, using an image file to determine which
2720 pixels comprise the logo. It works by filling in the pixels that
2721 comprise the logo with neighboring pixels.
2723 This filter requires one argument which specifies the filter bitmap
2724 file, which can be any image format supported by libavformat. The
2725 width and height of the image file must match those of the video
2726 stream being processed.
2728 Pixels in the provided bitmap image with a value of zero are not
2729 considered part of the logo, non-zero pixels are considered part of
2730 the logo. If you use white (255) for the logo and black (0) for the
2731 rest, you will be safe. For making the filter bitmap, it is
2732 recommended to take a screen capture of a black frame with the logo
2733 visible, and then using a threshold filter followed by the erode
2734 filter once or twice.
2736 If needed, little splotches can be fixed manually. Remember that if
2737 logo pixels are not covered, the filter quality will be much
2738 reduced. Marking too many pixels as part of the logo does not hurt as
2739 much, but it will increase the amount of blurring needed to cover over
2740 the image and will destroy more information than necessary, and extra
2741 pixels will slow things down on a large logo.
2745 Scale the input video to @var{width}:@var{height}[:@var{interl}=@{1|-1@}] and/or convert the image format.
2747 The scale filter forces the output display aspect ratio to be the same
2748 of the input, by changing the output sample aspect ratio.
2750 The parameters @var{width} and @var{height} are expressions containing
2751 the following constants:
2755 the input width and height
2758 same as @var{in_w} and @var{in_h}
2761 the output (cropped) width and height
2764 same as @var{out_w} and @var{out_h}
2767 same as @var{iw} / @var{ih}
2770 input sample aspect ratio
2773 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2776 horizontal and vertical chroma subsample values. For example for the
2777 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2780 If the input image format is different from the format requested by
2781 the next filter, the scale filter will convert the input to the
2784 If the value for @var{width} or @var{height} is 0, the respective input
2785 size is used for the output.
2787 If the value for @var{width} or @var{height} is -1, the scale filter will
2788 use, for the respective output size, a value that maintains the aspect
2789 ratio of the input image.
2791 The default value of @var{width} and @var{height} is 0.
2793 Valid values for the optional parameter @var{interl} are:
2797 force interlaced aware scaling
2800 select interlaced aware scaling depending on whether the source frames
2801 are flagged as interlaced or not
2804 Unless @var{interl} is set to one of the above options, interlaced scaling will not be used.
2806 Some examples follow:
2808 # scale the input video to a size of 200x100.
2811 # scale the input to 2x
2813 # the above is the same as
2816 # scale the input to 2x with forced interlaced scaling
2817 scale=2*iw:2*ih:interl=1
2819 # scale the input to half size
2822 # increase the width, and set the height to the same size
2825 # seek for Greek harmony
2829 # increase the height, and set the width to 3/2 of the height
2832 # increase the size, but make the size a multiple of the chroma
2833 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
2835 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
2836 scale='min(500\, iw*3/2):-1'
2840 Select frames to pass in output.
2842 It accepts in input an expression, which is evaluated for each input
2843 frame. If the expression is evaluated to a non-zero value, the frame
2844 is selected and passed to the output, otherwise it is discarded.
2846 The expression can contain the following constants:
2850 the sequential number of the filtered frame, starting from 0
2853 the sequential number of the selected frame, starting from 0
2855 @item prev_selected_n
2856 the sequential number of the last selected frame, NAN if undefined
2859 timebase of the input timestamps
2862 the PTS (Presentation TimeStamp) of the filtered video frame,
2863 expressed in @var{TB} units, NAN if undefined
2866 the PTS (Presentation TimeStamp) of the filtered video frame,
2867 expressed in seconds, NAN if undefined
2870 the PTS of the previously filtered video frame, NAN if undefined
2872 @item prev_selected_pts
2873 the PTS of the last previously filtered video frame, NAN if undefined
2875 @item prev_selected_t
2876 the PTS of the last previously selected video frame, NAN if undefined
2879 the PTS of the first video frame in the video, NAN if undefined
2882 the time of the first video frame in the video, NAN if undefined
2885 the type of the filtered frame, can assume one of the following
2897 @item interlace_type
2898 the frame interlace type, can assume one of the following values:
2901 the frame is progressive (not interlaced)
2903 the frame is top-field-first
2905 the frame is bottom-field-first
2909 1 if the filtered frame is a key-frame, 0 otherwise
2912 the position in the file of the filtered frame, -1 if the information
2913 is not available (e.g. for synthetic video)
2916 value between 0 and 1 to indicate a new scene; a low value reflects a low
2917 probability for the current frame to introduce a new scene, while a higher
2918 value means the current frame is more likely to be one (see the example below)
2922 The default value of the select expression is "1".
2924 Some examples follow:
2927 # select all frames in input
2930 # the above is the same as:
2936 # select only I-frames
2937 select='eq(pict_type\,I)'
2939 # select one frame every 100
2940 select='not(mod(n\,100))'
2942 # select only frames contained in the 10-20 time interval
2943 select='gte(t\,10)*lte(t\,20)'
2945 # select only I frames contained in the 10-20 time interval
2946 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2948 # select frames with a minimum distance of 10 seconds
2949 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2952 Complete example to create a mosaic of the first scenes:
2955 ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
2958 Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane
2961 @section setdar, setsar
2963 The @code{setdar} filter sets the Display Aspect Ratio for the filter
2966 This is done by changing the specified Sample (aka Pixel) Aspect
2967 Ratio, according to the following equation:
2969 @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR}
2972 Keep in mind that the @code{setdar} filter does not modify the pixel
2973 dimensions of the video frame. Also the display aspect ratio set by
2974 this filter may be changed by later filters in the filterchain,
2975 e.g. in case of scaling or if another "setdar" or a "setsar" filter is
2978 The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for
2979 the filter output video.
2981 Note that as a consequence of the application of this filter, the
2982 output display aspect ratio will change according to the equation
2985 Keep in mind that the sample aspect ratio set by the @code{setsar}
2986 filter may be changed by later filters in the filterchain, e.g. if
2987 another "setsar" or a "setdar" filter is applied.
2989 The @code{setdar} and @code{setsar} filters accept a parameter string
2990 which represents the wanted aspect ratio. The parameter can
2991 be a floating point number string, an expression, or a string of the form
2992 @var{num}:@var{den}, where @var{num} and @var{den} are the numerator
2993 and denominator of the aspect ratio. If the parameter is not
2994 specified, it is assumed the value "0:1".
2996 For example to change the display aspect ratio to 16:9, specify:
3001 The example above is equivalent to:
3006 To change the sample aspect ratio to 10:11, specify:
3013 Force field for the output video frame.
3015 The @code{setfield} filter marks the interlace type field for the
3016 output frames. It does not change the input frame, but only sets the
3017 corresponding property, which affects how the frame is treated by
3018 following filters (e.g. @code{fieldorder} or @code{yadif}).
3020 It accepts a string parameter, which can assume the following values:
3023 Keep the same field property.
3026 Mark the frame as bottom-field-first.
3029 Mark the frame as top-field-first.
3032 Mark the frame as progressive.
3035 @section asetpts, setpts
3037 Change the PTS (presentation timestamp) of the input frames.
3039 @code{asetpts} works on audio frames, @code{setpts} on video frames.
3041 Accept in input an expression evaluated through the eval API, which
3042 can contain the following constants:
3046 the presentation timestamp in input
3049 the count of the input frame, starting from 0.
3051 @item NB_CONSUMED_SAMPLES
3052 the number of consumed samples, not including the current frame (only
3056 the number of samples in the current frame (only audio)
3062 the PTS of the first video frame
3065 tell if the current frame is interlaced
3071 original position in the file of the frame, or undefined if undefined
3072 for the current frame
3082 Some examples follow:
3085 # start counting PTS from zero
3097 # fixed rate 25 fps with some jitter
3098 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
3100 # apply an offset of 10 seconds to the input PTS
3104 @section settb, asettb
3106 Set the timebase to use for the output frames timestamps.
3107 It is mainly useful for testing timebase configuration.
3109 It accepts in input an arithmetic expression representing a rational.
3110 The expression can contain the constants "AVTB" (the
3111 default timebase), "intb" (the input timebase) and "sr" (the sample rate,
3114 The default value for the input is "intb".
3116 Follow some examples.
3119 # set the timebase to 1/25
3122 # set the timebase to 1/10
3125 #set the timebase to 1001/1000
3128 #set the timebase to 2*intb
3131 #set the default timebase value
3137 Show a line containing various information for each input video frame.
3138 The input video is not modified.
3140 The shown line contains a sequence of key/value pairs of the form
3141 @var{key}:@var{value}.
3143 A description of each shown parameter follows:
3147 sequential number of the input frame, starting from 0
3150 Presentation TimeStamp of the input frame, expressed as a number of
3151 time base units. The time base unit depends on the filter input pad.
3154 Presentation TimeStamp of the input frame, expressed as a number of
3158 position of the frame in the input stream, -1 if this information in
3159 unavailable and/or meaningless (for example in case of synthetic video)
3165 sample aspect ratio of the input frame, expressed in the form
3169 size of the input frame, expressed in the form
3170 @var{width}x@var{height}
3173 interlaced mode ("P" for "progressive", "T" for top field first, "B"
3174 for bottom field first)
3177 1 if the frame is a key frame, 0 otherwise
3180 picture type of the input frame ("I" for an I-frame, "P" for a
3181 P-frame, "B" for a B-frame, "?" for unknown type).
3182 Check also the documentation of the @code{AVPictureType} enum and of
3183 the @code{av_get_picture_type_char} function defined in
3184 @file{libavutil/avutil.h}.
3187 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
3189 @item plane_checksum
3190 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
3191 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
3196 Pass the images of input video on to next video filter as multiple
3200 ffmpeg -i in.avi -vf "slicify=32" out.avi
3203 The filter accepts the slice height as parameter. If the parameter is
3204 not specified it will use the default value of 16.
3206 Adding this in the beginning of filter chains should make filtering
3207 faster due to better use of the memory cache.
3211 Split input video into several identical outputs.
3213 The filter accepts a single parameter which specifies the number of outputs. If
3214 unspecified, it defaults to 2.
3218 ffmpeg -i INPUT -filter_complex split=5 OUTPUT
3220 will create 5 copies of the input video.
3224 [in] split [splitout1][splitout2];
3225 [splitout1] crop=100:100:0:0 [cropout];
3226 [splitout2] pad=200:200:100:100 [padout];
3229 will create two separate outputs from the same input, one cropped and
3234 Scale the input by 2x and smooth using the Super2xSaI (Scale and
3235 Interpolate) pixel art scaling algorithm.
3237 Useful for enlarging pixel art images without reducing sharpness.
3243 Select the most representative frame in a given sequence of consecutive frames.
3245 It accepts as argument the frames batch size to analyze (default @var{N}=100);
3246 in a set of @var{N} frames, the filter will pick one of them, and then handle
3247 the next batch of @var{N} frames until the end.
3249 Since the filter keeps track of the whole frames sequence, a bigger @var{N}
3250 value will result in a higher memory usage, so a high value is not recommended.
3252 The following example extract one picture each 50 frames:
3257 Complete example of a thumbnail creation with @command{ffmpeg}:
3259 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
3264 Tile several successive frames together.
3266 It accepts as argument the tile size (i.e. the number of lines and columns)
3267 in the form "@var{w}x@var{h}".
3269 For example, produce 8×8 PNG tiles of all keyframes (@option{-skip_frame
3272 ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
3274 The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from
3275 duplicating each output frame to accomodate the originally detected frame
3280 Perform various types of temporal field interlacing.
3282 Frames are counted starting from 1, so the first input frame is
3285 This filter accepts a single parameter specifying the mode. Available
3290 Move odd frames into the upper field, even into the lower field,
3291 generating a double height frame at half framerate.
3294 Only output even frames, odd frames are dropped, generating a frame with
3295 unchanged height at half framerate.
3298 Only output odd frames, even frames are dropped, generating a frame with
3299 unchanged height at half framerate.
3302 Expand each frame to full height, but pad alternate lines with black,
3303 generating a frame with double height at the same input framerate.
3305 @item interleave_top, 4
3306 Interleave the upper field from odd frames with the lower field from
3307 even frames, generating a frame with unchanged height at half framerate.
3309 @item interleave_bottom, 5
3310 Interleave the lower field from odd frames with the upper field from
3311 even frames, generating a frame with unchanged height at half framerate.
3313 @item interlacex2, 6
3314 Double frame rate with unchanged height. Frames are inserted each
3315 containing the second temporal field from the previous input frame and
3316 the first temporal field from the next input frame. This mode relies on
3317 the top_field_first flag. Useful for interlaced video displays with no
3318 field synchronisation.
3321 Numeric values are deprecated but are accepted for backward
3322 compatibility reasons.
3324 Default mode is @code{merge}.
3328 Transpose rows with columns in the input video and optionally flip it.
3330 It accepts a parameter representing an integer, which can assume the
3335 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
3343 Rotate by 90 degrees clockwise, that is:
3351 Rotate by 90 degrees counterclockwise, that is:
3359 Rotate by 90 degrees clockwise and vertically flip, that is:
3369 Sharpen or blur the input video.
3371 It accepts the following parameters:
3372 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
3374 Negative values for the amount will blur the input video, while positive
3375 values will sharpen. All parameters are optional and default to the
3376 equivalent of the string '5:5:1.0:5:5:0.0'.
3381 Set the luma matrix horizontal size. It can be an integer between 3
3382 and 13, default value is 5.
3385 Set the luma matrix vertical size. It can be an integer between 3
3386 and 13, default value is 5.
3389 Set the luma effect strength. It can be a float number between -2.0
3390 and 5.0, default value is 1.0.
3392 @item chroma_msize_x
3393 Set the chroma matrix horizontal size. It can be an integer between 3
3394 and 13, default value is 5.
3396 @item chroma_msize_y
3397 Set the chroma matrix vertical size. It can be an integer between 3
3398 and 13, default value is 5.
3401 Set the chroma effect strength. It can be a float number between -2.0
3402 and 5.0, default value is 0.0.
3407 # Strong luma sharpen effect parameters
3410 # Strong blur of both luma and chroma parameters
3411 unsharp=7:7:-2:7:7:-2
3413 # Use the default values with @command{ffmpeg}
3414 ffmpeg -i in.avi -vf "unsharp" out.mp4
3419 Flip the input video vertically.
3422 ffmpeg -i in.avi -vf "vflip" out.avi
3427 Deinterlace the input video ("yadif" means "yet another deinterlacing
3430 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
3432 @var{mode} specifies the interlacing mode to adopt, accepts one of the
3437 output 1 frame for each frame
3439 output 1 frame for each field
3441 like 0 but skips spatial interlacing check
3443 like 1 but skips spatial interlacing check
3448 @var{parity} specifies the picture field parity assumed for the input
3449 interlaced video, accepts one of the following values:
3453 assume top field first
3455 assume bottom field first
3457 enable automatic detection
3460 Default value is -1.
3461 If interlacing is unknown or decoder does not export this information,
3462 top field first will be assumed.
3464 @var{auto} specifies if deinterlacer should trust the interlaced flag
3465 and only deinterlace frames marked as interlaced
3469 deinterlace all frames
3471 only deinterlace frames marked as interlaced
3476 @c man end VIDEO FILTERS
3478 @chapter Video Sources
3479 @c man begin VIDEO SOURCES
3481 Below is a description of the currently available video sources.
3485 Buffer video frames, and make them available to the filter chain.
3487 This source is mainly intended for a programmatic use, in particular
3488 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
3490 It accepts a list of options in the form of @var{key}=@var{value} pairs
3491 separated by ":". A descroption of the accepted options follows.
3496 Specify the size (width and height) of the buffered video frames.
3499 A string representing the pixel format of the buffered video frames.
3500 It may be a number corresponding to a pixel format, or a pixel format
3504 Specify the timebase assumed by the timestamps of the buffered frames.
3507 Specify the frame rate expected for the video stream.
3510 Specify the sample aspect ratio assumed by the video frames.
3513 Specify the optional parameters to be used for the scale filter which
3514 is automatically inserted when an input change is detected in the
3515 input size or format.
3520 buffer=size=320x240:pix_fmt=yuv410p:time_base=1/24:pixel_aspect=1/1
3523 will instruct the source to accept video frames with size 320x240 and
3524 with format "yuv410p", assuming 1/24 as the timestamps timebase and
3525 square pixels (1:1 sample aspect ratio).
3526 Since the pixel format with name "yuv410p" corresponds to the number 6
3527 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
3528 this example corresponds to:
3530 buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
3533 Alternatively, the options can be specified as a flat string, but this
3534 syntax is deprecated:
3536 @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}]
3540 Create a pattern generated by an elementary cellular automaton.
3542 The initial state of the cellular automaton can be defined through the
3543 @option{filename}, and @option{pattern} options. If such options are
3544 not specified an initial state is created randomly.
3546 At each new frame a new row in the video is filled with the result of
3547 the cellular automaton next generation. The behavior when the whole
3548 frame is filled is defined by the @option{scroll} option.
3550 This source accepts a list of options in the form of
3551 @var{key}=@var{value} pairs separated by ":". A description of the
3552 accepted options follows.
3556 Read the initial cellular automaton state, i.e. the starting row, from
3558 In the file, each non-whitespace character is considered an alive
3559 cell, a newline will terminate the row, and further characters in the
3560 file will be ignored.
3563 Read the initial cellular automaton state, i.e. the starting row, from
3564 the specified string.
3566 Each non-whitespace character in the string is considered an alive
3567 cell, a newline will terminate the row, and further characters in the
3568 string will be ignored.
3571 Set the video rate, that is the number of frames generated per second.
3574 @item random_fill_ratio, ratio
3575 Set the random fill ratio for the initial cellular automaton row. It
3576 is a floating point number value ranging from 0 to 1, defaults to
3579 This option is ignored when a file or a pattern is specified.
3581 @item random_seed, seed
3582 Set the seed for filling randomly the initial row, must be an integer
3583 included between 0 and UINT32_MAX. If not specified, or if explicitly
3584 set to -1, the filter will try to use a good random seed on a best
3588 Set the cellular automaton rule, it is a number ranging from 0 to 255.
3589 Default value is 110.
3592 Set the size of the output video.
3594 If @option{filename} or @option{pattern} is specified, the size is set
3595 by default to the width of the specified initial state row, and the
3596 height is set to @var{width} * PHI.
3598 If @option{size} is set, it must contain the width of the specified
3599 pattern string, and the specified pattern will be centered in the
3602 If a filename or a pattern string is not specified, the size value
3603 defaults to "320x518" (used for a randomly generated initial state).
3606 If set to 1, scroll the output upward when all the rows in the output
3607 have been already filled. If set to 0, the new generated row will be
3608 written over the top row just after the bottom row is filled.
3611 @item start_full, full
3612 If set to 1, completely fill the output with generated rows before
3613 outputting the first frame.
3614 This is the default behavior, for disabling set the value to 0.
3617 If set to 1, stitch the left and right row edges together.
3618 This is the default behavior, for disabling set the value to 0.
3621 @subsection Examples
3625 Read the initial state from @file{pattern}, and specify an output of
3628 cellauto=f=pattern:s=200x400
3632 Generate a random initial row with a width of 200 cells, with a fill
3635 cellauto=ratio=2/3:s=200x200
3639 Create a pattern generated by rule 18 starting by a single alive cell
3640 centered on an initial row with width 100:
3642 cellauto=p=@@:s=100x400:full=0:rule=18
3646 Specify a more elaborated initial pattern:
3648 cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18
3655 Generate a Mandelbrot set fractal, and progressively zoom towards the
3656 point specified with @var{start_x} and @var{start_y}.
3658 This source accepts a list of options in the form of
3659 @var{key}=@var{value} pairs separated by ":". A description of the
3660 accepted options follows.
3665 Set the terminal pts value. Default value is 400.
3668 Set the terminal scale value.
3669 Must be a floating point value. Default value is 0.3.
3672 Set the inner coloring mode, that is the algorithm used to draw the
3673 Mandelbrot fractal internal region.
3675 It shall assume one of the following values:
3680 Show time until convergence.
3682 Set color based on point closest to the origin of the iterations.
3687 Default value is @var{mincol}.
3690 Set the bailout value. Default value is 10.0.
3693 Set the maximum of iterations performed by the rendering
3694 algorithm. Default value is 7189.
3697 Set outer coloring mode.
3698 It shall assume one of following values:
3700 @item iteration_count
3701 Set iteration cound mode.
3702 @item normalized_iteration_count
3703 set normalized iteration count mode.
3705 Default value is @var{normalized_iteration_count}.
3708 Set frame rate, expressed as number of frames per second. Default
3712 Set frame size. Default value is "640x480".
3715 Set the initial scale value. Default value is 3.0.
3718 Set the initial x position. Must be a floating point value between
3719 -100 and 100. Default value is -0.743643887037158704752191506114774.
3722 Set the initial y position. Must be a floating point value between
3723 -100 and 100. Default value is -0.131825904205311970493132056385139.
3728 Generate various test patterns, as generated by the MPlayer test filter.
3730 The size of the generated video is fixed, and is 256x256.
3731 This source is useful in particular for testing encoding features.
3733 This source accepts an optional sequence of @var{key}=@var{value} pairs,
3734 separated by ":". The description of the accepted options follows.
3739 Specify the frame rate of the sourced video, as the number of frames
3740 generated per second. It has to be a string in the format
3741 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3742 number or a valid video frame rate abbreviation. The default value is
3746 Set the video duration of the sourced video. The accepted syntax is:
3751 See also the function @code{av_parse_time()}.
3753 If not specified, or the expressed duration is negative, the video is
3754 supposed to be generated forever.
3758 Set the number or the name of the test to perform. Supported tests are:
3773 Default value is "all", which will cycle through the list of all tests.
3776 For example the following:
3781 will generate a "dc_luma" test pattern.
3785 Provide a frei0r source.
3787 To enable compilation of this filter you need to install the frei0r
3788 header and configure FFmpeg with @code{--enable-frei0r}.
3790 The source supports the syntax:
3792 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
3795 @var{size} is the size of the video to generate, may be a string of the
3796 form @var{width}x@var{height} or a frame size abbreviation.
3797 @var{rate} is the rate of the video to generate, may be a string of
3798 the form @var{num}/@var{den} or a frame rate abbreviation.
3799 @var{src_name} is the name to the frei0r source to load. For more
3800 information regarding frei0r and how to set the parameters read the
3801 section @ref{frei0r} in the description of the video filters.
3803 For example, to generate a frei0r partik0l source with size 200x200
3804 and frame rate 10 which is overlayed on the overlay filter main input:
3806 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
3811 Generate a life pattern.
3813 This source is based on a generalization of John Conway's life game.
3815 The sourced input represents a life grid, each pixel represents a cell
3816 which can be in one of two possible states, alive or dead. Every cell
3817 interacts with its eight neighbours, which are the cells that are
3818 horizontally, vertically, or diagonally adjacent.
3820 At each interaction the grid evolves according to the adopted rule,
3821 which specifies the number of neighbor alive cells which will make a
3822 cell stay alive or born. The @option{rule} option allows to specify
3825 This source accepts a list of options in the form of
3826 @var{key}=@var{value} pairs separated by ":". A description of the
3827 accepted options follows.
3831 Set the file from which to read the initial grid state. In the file,
3832 each non-whitespace character is considered an alive cell, and newline
3833 is used to delimit the end of each row.
3835 If this option is not specified, the initial grid is generated
3839 Set the video rate, that is the number of frames generated per second.
3842 @item random_fill_ratio, ratio
3843 Set the random fill ratio for the initial random grid. It is a
3844 floating point number value ranging from 0 to 1, defaults to 1/PHI.
3845 It is ignored when a file is specified.
3847 @item random_seed, seed
3848 Set the seed for filling the initial random grid, must be an integer
3849 included between 0 and UINT32_MAX. If not specified, or if explicitly
3850 set to -1, the filter will try to use a good random seed on a best
3856 A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}",
3857 where @var{NS} and @var{NB} are sequences of numbers in the range 0-8,
3858 @var{NS} specifies the number of alive neighbor cells which make a
3859 live cell stay alive, and @var{NB} the number of alive neighbor cells
3860 which make a dead cell to become alive (i.e. to "born").
3861 "s" and "b" can be used in place of "S" and "B", respectively.
3863 Alternatively a rule can be specified by an 18-bits integer. The 9
3864 high order bits are used to encode the next cell state if it is alive
3865 for each number of neighbor alive cells, the low order bits specify
3866 the rule for "borning" new cells. Higher order bits encode for an
3867 higher number of neighbor cells.
3868 For example the number 6153 = @code{(12<<9)+9} specifies a stay alive
3869 rule of 12 and a born rule of 9, which corresponds to "S23/B03".
3871 Default value is "S23/B3", which is the original Conway's game of life
3872 rule, and will keep a cell alive if it has 2 or 3 neighbor alive
3873 cells, and will born a new cell if there are three alive cells around
3877 Set the size of the output video.
3879 If @option{filename} is specified, the size is set by default to the
3880 same size of the input file. If @option{size} is set, it must contain
3881 the size specified in the input file, and the initial grid defined in
3882 that file is centered in the larger resulting area.
3884 If a filename is not specified, the size value defaults to "320x240"
3885 (used for a randomly generated initial grid).
3888 If set to 1, stitch the left and right grid edges together, and the
3889 top and bottom edges also. Defaults to 1.
3892 Set cell mold speed. If set, a dead cell will go from @option{death_color} to
3893 @option{mold_color} with a step of @option{mold}. @option{mold} can have a
3894 value from 0 to 255.
3897 Set the color of living (or new born) cells.
3900 Set the color of dead cells. If @option{mold} is set, this is the first color
3901 used to represent a dead cell.
3904 Set mold color, for definitely dead and moldy cells.
3907 @subsection Examples
3911 Read a grid from @file{pattern}, and center it on a grid of size
3914 life=f=pattern:s=300x300
3918 Generate a random grid of size 200x200, with a fill ratio of 2/3:
3920 life=ratio=2/3:s=200x200
3924 Specify a custom rule for evolving a randomly generated grid:
3930 Full example with slow death effect (mold) using @command{ffplay}:
3932 ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
3936 @section color, nullsrc, rgbtestsrc, smptebars, testsrc
3938 The @code{color} source provides an uniformly colored input.
3940 The @code{nullsrc} source returns unprocessed video frames. It is
3941 mainly useful to be employed in analysis / debugging tools, or as the
3942 source for filters which ignore the input data.
3944 The @code{rgbtestsrc} source generates an RGB test pattern useful for
3945 detecting RGB vs BGR issues. You should see a red, green and blue
3946 stripe from top to bottom.
3948 The @code{smptebars} source generates a color bars pattern, based on
3949 the SMPTE Engineering Guideline EG 1-1990.
3951 The @code{testsrc} source generates a test video pattern, showing a
3952 color pattern, a scrolling gradient and a timestamp. This is mainly
3953 intended for testing purposes.
3955 These sources accept an optional sequence of @var{key}=@var{value} pairs,
3956 separated by ":". The description of the accepted options follows.
3961 Specify the color of the source, only used in the @code{color}
3962 source. It can be the name of a color (case insensitive match) or a
3963 0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The
3964 default value is "black".
3967 Specify the size of the sourced video, it may be a string of the form
3968 @var{width}x@var{height}, or the name of a size abbreviation. The
3969 default value is "320x240".
3972 Specify the frame rate of the sourced video, as the number of frames
3973 generated per second. It has to be a string in the format
3974 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
3975 number or a valid video frame rate abbreviation. The default value is
3979 Set the sample aspect ratio of the sourced video.
3982 Set the video duration of the sourced video. The accepted syntax is:
3984 [-]HH[:MM[:SS[.m...]]]
3987 See also the function @code{av_parse_time()}.
3989 If not specified, or the expressed duration is negative, the video is
3990 supposed to be generated forever.
3993 Set the number of decimals to show in the timestamp, only used in the
3994 @code{testsrc} source.
3996 The displayed timestamp value will correspond to the original
3997 timestamp value multiplied by the power of 10 of the specified
3998 value. Default value is 0.
4001 For example the following:
4003 testsrc=duration=5.3:size=qcif:rate=10
4006 will generate a video with a duration of 5.3 seconds, with size
4007 176x144 and a frame rate of 10 frames per second.
4009 The following graph description will generate a red source
4010 with an opacity of 0.2, with size "qcif" and a frame rate of 10
4013 color=c=red@@0.2:s=qcif:r=10
4016 If the input content is to be ignored, @code{nullsrc} can be used. The
4017 following command generates noise in the luminance plane by employing
4018 the @code{mp=geq} filter:
4020 nullsrc=s=256x256, mp=geq=random(1)*255:128:128
4023 @c man end VIDEO SOURCES
4025 @chapter Video Sinks
4026 @c man begin VIDEO SINKS
4028 Below is a description of the currently available video sinks.
4032 Buffer video frames, and make them available to the end of the filter
4035 This sink is mainly intended for a programmatic use, in particular
4036 through the interface defined in @file{libavfilter/buffersink.h}.
4038 It does not require a string parameter in input, but you need to
4039 specify a pointer to a list of supported pixel formats terminated by
4040 -1 in the opaque parameter provided to @code{avfilter_init_filter}
4041 when initializing this sink.
4045 Null video sink, do absolutely nothing with the input video. It is
4046 mainly useful as a template and to be employed in analysis / debugging
4049 @c man end VIDEO SINKS
4051 @chapter Multimedia Filters
4052 @c man begin MULTIMEDIA FILTERS
4054 Below is a description of the currently available multimedia filters.
4058 Concatenate audio and video streams, joining them together one after the
4061 The filter works on segments of synchronized video and audio streams. All
4062 segments must have the same number of streams of each type, and that will
4063 also be the number of streams at output.
4065 The filter accepts the following named parameters:
4069 Set the number of segments. Default is 2.
4072 Set the number of output video streams, that is also the number of video
4073 streams in each segment. Default is 1.
4076 Set the number of output audio streams, that is also the number of video
4077 streams in each segment. Default is 0.
4081 The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then
4082 @var{a} audio outputs.
4084 There are @var{n}×(@var{v}+@var{a}) inputs: first the inputs for the first
4085 segment, in the same order as the outputs, then the inputs for the second
4088 Related streams do not always have exactly the same duration, for various
4089 reasons including codec frame size or sloppy authoring. For that reason,
4090 related synchronized streams (e.g. a video and its audio track) should be
4091 concatenated at once. The concat filter will use the duration of the longest
4092 stream in each segment (except the last one), and if necessary pad shorter
4093 audio streams with silence.
4095 For this filter to work correctly, all segments must start at timestamp 0.
4097 All corresponding streams must have the same parameters in all segments; the
4098 filtering system will automatically select a common pixel format for video
4099 streams, and a common sample format, sample rate and channel layout for
4100 audio streams, but other settings, such as resolution, must be converted
4101 explicitly by the user.
4103 Different frame rates are acceptable but will result in variable frame rate
4104 at output; be sure to configure the output file to handle it.
4109 Concatenate an opening, an episode and an ending, all in bilingual version
4110 (video in stream 0, audio in streams 1 and 2):
4112 ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
4113 '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
4114 concat=n=3:v=1:a=2 [v] [a1] [a2]' \
4115 -map '[v]' -map '[a1]' -map '[a2]' output.mkv
4119 Concatenate two parts, handling audio and video separately, using the
4120 (a)movie sources, and adjusting the resolution:
4122 movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
4123 movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
4124 [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
4126 Note that a desync will happen at the stitch if the audio and video streams
4127 do not have exactly the same duration in the first file.
4133 Convert input audio to a video output, representing the samples waves.
4135 The filter accepts the following named parameters:
4139 Set the number of samples which are printed on the same column. A
4140 larger value will decrease the frame rate. Must be a positive
4141 integer. This option can be set only if the value for @var{rate}
4142 is not explicitly specified.
4145 Set the (approximate) output frame rate. This is done by setting the
4146 option @var{n}. Default value is "25".
4149 Specify the video size for the output. Default value is "600x240".
4152 Some examples follow.
4155 Output the input file audio and the corresponding video representation
4158 amovie=a.mp3,asplit[out0],showwaves[out1]
4162 Create a synthetic signal and show it with showwaves, forcing a
4163 framerate of 30 frames per second:
4165 aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
4169 @c man end MULTIMEDIA FILTERS
4171 @chapter Multimedia Sources
4172 @c man begin MULTIMEDIA SOURCES
4174 Below is a description of the currently available multimedia sources.
4178 This is the same as @ref{src_movie} source, except it selects an audio
4184 Read audio and/or video stream(s) from a movie container.
4186 It accepts the syntax: @var{movie_name}[:@var{options}] where
4187 @var{movie_name} is the name of the resource to read (not necessarily
4188 a file but also a device or a stream accessed through some protocol),
4189 and @var{options} is an optional sequence of @var{key}=@var{value}
4190 pairs, separated by ":".
4192 The description of the accepted options follows.
4196 @item format_name, f
4197 Specifies the format assumed for the movie to read, and can be either
4198 the name of a container or an input device. If not specified the
4199 format is guessed from @var{movie_name} or by probing.
4201 @item seek_point, sp
4202 Specifies the seek point in seconds, the frames will be output
4203 starting from this seek point, the parameter is evaluated with
4204 @code{av_strtod} so the numerical value may be suffixed by an IS
4205 postfix. Default value is "0".
4208 Specifies the streams to read. Several streams can be specified, separated
4209 by "+". The source will then have as many outputs, in the same order. The
4210 syntax is explained in the @ref{Stream specifiers} chapter. Two special
4211 names, "dv" and "da" specify respectively the default (best suited) video
4212 and audio stream. Default is "dv", or "da" if the filter is called as
4215 @item stream_index, si
4216 Specifies the index of the video stream to read. If the value is -1,
4217 the best suited video stream will be automatically selected. Default
4218 value is "-1". Deprecated. If the filter is called "amovie", it will select
4219 audio instead of video.
4222 Specifies how many times to read the stream in sequence.
4223 If the value is less than 1, the stream will be read again and again.
4224 Default value is "1".
4226 Note that when the movie is looped the source timestamps are not
4227 changed, so it will generate non monotonically increasing timestamps.
4230 This filter allows to overlay a second video on top of main input of
4231 a filtergraph as shown in this graph:
4233 input -----------> deltapts0 --> overlay --> output
4236 movie --> scale--> deltapts1 -------+
4239 Some examples follow.
4243 Skip 3.2 seconds from the start of the avi file in.avi, and overlay it
4244 on top of the input labelled as "in":
4246 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
4247 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
4251 Read from a video4linux2 device, and overlay it on top of the input
4254 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
4255 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
4259 Read the first video stream and the audio stream with id 0x81 from
4260 dvd.vob; the video is connected to the pad named "video" and the audio is
4261 connected to the pad named "audio":
4263 movie=dvd.vob:s=v:0+#0x81 [video] [audio]
4267 @c man end MULTIMEDIA SOURCES