af_volume: support using replaygain frame side data
[libav.git] / doc / filters.texi
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1@chapter Filtergraph description
2@c man begin FILTERGRAPH DESCRIPTION
3
4A filtergraph is a directed graph of connected filters. It can contain
5cycles, and there can be multiple links between a pair of
6filters. Each link has one input pad on one side connecting it to one
7filter from which it takes its input, and one output pad on the other
8side connecting it to the one filter accepting its output.
9
10Each filter in a filtergraph is an instance of a filter class
11registered in the application, which defines the features and the
12number of input and output pads of the filter.
13
14A filter with no input pads is called a "source", a filter with no
15output pads is called a "sink".
16
3b266da3 17@anchor{Filtergraph syntax}
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18@section Filtergraph syntax
19
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20A filtergraph can be represented using a textual representation, which is
21recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
22options in @command{avconv} and @option{-vf} in @command{avplay}, and by the
23@code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
38f0c078 24@file{libavfilter/avfilter.h}.
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25
26A filterchain consists of a sequence of connected filters, each one
27connected to the previous one in the sequence. A filterchain is
28represented by a list of ","-separated filter descriptions.
29
30A filtergraph consists of a sequence of filterchains. A sequence of
31filterchains is represented by a list of ";"-separated filterchain
32descriptions.
33
34A filter is represented by a string of the form:
35[@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
36
37@var{filter_name} is the name of the filter class of which the
38described filter is an instance of, and has to be the name of one of
39the filter classes registered in the program.
40The name of the filter class is optionally followed by a string
41"=@var{arguments}".
42
43@var{arguments} is a string which contains the parameters used to
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44initialize the filter instance. It may have one of the two allowed forms:
45@itemize
46
47@item
48A ':'-separated list of @var{key=value} pairs.
49
50@item
51A ':'-separated list of @var{value}. In this case, the keys are assumed to be
52the option names in the order they are declared. E.g. the @code{fade} filter
53declares three options in this order -- @option{type}, @option{start_frame} and
54@option{nb_frames}. Then the parameter list @var{in:0:30} means that the value
55@var{in} is assigned to the option @option{type}, @var{0} to
56@option{start_frame} and @var{30} to @option{nb_frames}.
57
58@end itemize
59
60If the option value itself is a list of items (e.g. the @code{format} filter
61takes a list of pixel formats), the items in the list are usually separated by
62'|'.
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63
64The list of arguments can be quoted using the character "'" as initial
65and ending mark, and the character '\' for escaping the characters
66within the quoted text; otherwise the argument string is considered
67terminated when the next special character (belonging to the set
68"[]=;,") is encountered.
69
70The name and arguments of the filter are optionally preceded and
71followed by a list of link labels.
72A link label allows to name a link and associate it to a filter output
73or input pad. The preceding labels @var{in_link_1}
74... @var{in_link_N}, are associated to the filter input pads,
75the following labels @var{out_link_1} ... @var{out_link_M}, are
76associated to the output pads.
77
78When two link labels with the same name are found in the
79filtergraph, a link between the corresponding input and output pad is
80created.
81
82If an output pad is not labelled, it is linked by default to the first
83unlabelled input pad of the next filter in the filterchain.
84For example in the filterchain:
85@example
86nullsrc, split[L1], [L2]overlay, nullsink
87@end example
88the split filter instance has two output pads, and the overlay filter
89instance two input pads. The first output pad of split is labelled
90"L1", the first input pad of overlay is labelled "L2", and the second
91output pad of split is linked to the second input pad of overlay,
92which are both unlabelled.
93
94In a complete filterchain all the unlabelled filter input and output
95pads must be connected. A filtergraph is considered valid if all the
96filter input and output pads of all the filterchains are connected.
97
dd249245 98Libavfilter will automatically insert @ref{scale} filters where format
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99conversion is required. It is possible to specify swscale flags
100for those automatically inserted scalers by prepending
101@code{sws_flags=@var{flags};}
102to the filtergraph description.
103
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104Follows a BNF description for the filtergraph syntax:
105@example
106@var{NAME} ::= sequence of alphanumeric characters and '_'
107@var{LINKLABEL} ::= "[" @var{NAME} "]"
108@var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
109@var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
b5ad422b 110@var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}]
1ebe5c4c 111@var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
12e7e1d0 112@var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
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113@end example
114
115@c man end FILTERGRAPH DESCRIPTION
116
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117@chapter Audio Filters
118@c man begin AUDIO FILTERS
119
f8a45fa1 120When you configure your Libav build, you can disable any of the
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121existing filters using --disable-filters.
122The configure output will show the audio filters included in your
123build.
124
125Below is a description of the currently available audio filters.
126
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127@section aformat
128
129Convert the input audio to one of the specified formats. The framework will
130negotiate the most appropriate format to minimize conversions.
131
132The filter accepts the following named parameters:
133@table @option
134
135@item sample_fmts
0af7fe1f 136A '|'-separated list of requested sample formats.
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137
138@item sample_rates
0af7fe1f 139A '|'-separated list of requested sample rates.
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140
141@item channel_layouts
0af7fe1f 142A '|'-separated list of requested channel layouts.
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143
144@end table
145
146If a parameter is omitted, all values are allowed.
147
148For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
149@example
0af7fe1f 150aformat=sample_fmts=u8|s16:channel_layouts=stereo
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151@end example
152
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153@section amix
154
155Mixes multiple audio inputs into a single output.
156
157For example
158@example
159avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
160@end example
161will mix 3 input audio streams to a single output with the same duration as the
162first input and a dropout transition time of 3 seconds.
163
164The filter accepts the following named parameters:
165@table @option
166
167@item inputs
168Number of inputs. If unspecified, it defaults to 2.
169
170@item duration
171How to determine the end-of-stream.
172@table @option
173
174@item longest
175Duration of longest input. (default)
176
177@item shortest
178Duration of shortest input.
179
180@item first
181Duration of first input.
182
183@end table
184
185@item dropout_transition
186Transition time, in seconds, for volume renormalization when an input
187stream ends. The default value is 2 seconds.
188
189@end table
190
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191@section anull
192
193Pass the audio source unchanged to the output.
194
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195@section asetpts
196
197Change the PTS (presentation timestamp) of the input audio frames.
198
199This filter accepts the following options:
200
201@table @option
202
203@item expr
204The expression which is evaluated for each frame to construct its timestamp.
205
206@end table
207
208The expression is evaluated through the eval API and can contain the following
209constants:
210
211@table @option
212@item PTS
213the presentation timestamp in input
214
215@item PI
216Greek PI
217
218@item PHI
219golden ratio
220
221@item E
222Euler number
223
224@item N
225Number of the audio samples pass through the filter so far, starting at 0.
226
227@item S
228Number of the audio samples in the current frame.
229
230@item SR
231Audio sample rate.
232
233@item STARTPTS
234the PTS of the first frame
235
236@item PREV_INPTS
237previous input PTS
238
239@item PREV_OUTPTS
240previous output PTS
241
242@item RTCTIME
243wallclock (RTC) time in microseconds
244
245@item RTCSTART
246wallclock (RTC) time at the start of the movie in microseconds
247
248@end table
249
250Some examples follow:
251
252@example
253# start counting PTS from zero
254asetpts=expr=PTS-STARTPTS
255
256#generate timestamps by counting samples
257asetpts=expr=N/SR/TB
258
259# generate timestamps from a "live source" and rebase onto the current timebase
260asetpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
261@end example
262
263
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264@section ashowinfo
265
266Show a line containing various information for each input audio frame.
267The input audio is not modified.
268
269The shown line contains a sequence of key/value pairs of the form
270@var{key}:@var{value}.
271
272A description of each shown parameter follows:
273
274@table @option
275@item n
276sequential number of the input frame, starting from 0
277
278@item pts
279Presentation timestamp of the input frame, in time base units; the time base
280depends on the filter input pad, and is usually 1/@var{sample_rate}.
281
282@item pts_time
283presentation timestamp of the input frame in seconds
284
285@item fmt
286sample format
287
288@item chlayout
289channel layout
290
291@item rate
292sample rate for the audio frame
293
294@item nb_samples
295number of samples (per channel) in the frame
296
297@item checksum
298Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio
299the data is treated as if all the planes were concatenated.
300
301@item plane_checksums
302A list of Adler-32 checksums for each data plane.
303@end table
304
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305@section asplit
306
307Split input audio into several identical outputs.
308
309The filter accepts a single parameter which specifies the number of outputs. If
310unspecified, it defaults to 2.
311
312For example
313@example
314avconv -i INPUT -filter_complex asplit=5 OUTPUT
315@end example
316will create 5 copies of the input audio.
317
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318@section asyncts
319Synchronize audio data with timestamps by squeezing/stretching it and/or
320dropping samples/adding silence when needed.
321
322The filter accepts the following named parameters:
323@table @option
324
325@item compensate
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326Enable stretching/squeezing the data to make it match the timestamps. Disabled
327by default. When disabled, time gaps are covered with silence.
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328
329@item min_delta
330Minimum difference between timestamps and audio data (in seconds) to trigger
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331adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
332this filter, try setting this parameter to 0.
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333
334@item max_comp
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335Maximum compensation in samples per second. Relevant only with compensate=1.
336Default value 500.
9f26421b 337
70d71b58 338@item first_pts
b35e5d98 339Assume the first pts should be this value. The time base is 1 / sample rate.
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340This allows for padding/trimming at the start of stream. By default, no
341assumption is made about the first frame's expected pts, so no padding or
342trimming is done. For example, this could be set to 0 to pad the beginning with
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343silence if an audio stream starts after the video stream or to trim any samples
344with a negative pts due to encoder delay.
70d71b58 345
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346@end table
347
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348@section atrim
349Trim the input so that the output contains one continuous subpart of the input.
350
351This filter accepts the following options:
352@table @option
353@item start
354Timestamp (in seconds) of the start of the kept section. I.e. the audio sample
355with the timestamp @var{start} will be the first sample in the output.
356
357@item end
358Timestamp (in seconds) of the first audio sample that will be dropped. I.e. the
359audio sample immediately preceding the one with the timestamp @var{end} will be
360the last sample in the output.
361
362@item start_pts
363Same as @var{start}, except this option sets the start timestamp in samples
364instead of seconds.
365
366@item end_pts
367Same as @var{end}, except this option sets the end timestamp in samples instead
368of seconds.
369
370@item duration
371Maximum duration of the output in seconds.
372
373@item start_sample
374Number of the first sample that should be passed to output.
375
376@item end_sample
377Number of the first sample that should be dropped.
378@end table
379
380Note that the first two sets of the start/end options and the @option{duration}
381option look at the frame timestamp, while the _sample options simply count the
382samples that pass through the filter. So start/end_pts and start/end_sample will
383give different results when the timestamps are wrong, inexact or do not start at
384zero. Also note that this filter does not modify the timestamps. If you wish
385that the output timestamps start at zero, insert the asetpts filter after the
386atrim filter.
387
388If multiple start or end options are set, this filter tries to be greedy and
389keep all samples that match at least one of the specified constraints. To keep
390only the part that matches all the constraints at once, chain multiple atrim
391filters.
392
393The defaults are such that all the input is kept. So it is possible to set e.g.
394just the end values to keep everything before the specified time.
395
396Examples:
397@itemize
398@item
399drop everything except the second minute of input
400@example
401avconv -i INPUT -af atrim=60:120
402@end example
403
404@item
405keep only the first 1000 samples
406@example
407avconv -i INPUT -af atrim=end_sample=1000
408@end example
409
410@end itemize
411
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412@section channelsplit
413Split each channel in input audio stream into a separate output stream.
414
415This filter accepts the following named parameters:
416@table @option
417@item channel_layout
418Channel layout of the input stream. Default is "stereo".
419@end table
420
421For example, assuming a stereo input MP3 file
422@example
423avconv -i in.mp3 -filter_complex channelsplit out.mkv
424@end example
425will create an output Matroska file with two audio streams, one containing only
426the left channel and the other the right channel.
427
428To split a 5.1 WAV file into per-channel files
429@example
430avconv -i in.wav -filter_complex
431'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
432-map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
433front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
434side_right.wav
435@end example
436
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437@section channelmap
438Remap input channels to new locations.
439
440This filter accepts the following named parameters:
441@table @option
442@item channel_layout
443Channel layout of the output stream.
444
445@item map
ba8efac9 446Map channels from input to output. The argument is a '|'-separated list of
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447mappings, each in the @code{@var{in_channel}-@var{out_channel}} or
448@var{in_channel} form. @var{in_channel} can be either the name of the input
449channel (e.g. FL for front left) or its index in the input channel layout.
450@var{out_channel} is the name of the output channel or its index in the output
451channel layout. If @var{out_channel} is not given then it is implicitly an
452index, starting with zero and increasing by one for each mapping.
453@end table
454
455If no mapping is present, the filter will implicitly map input channels to
456output channels preserving index.
457
458For example, assuming a 5.1+downmix input MOV file
459@example
ba8efac9 460avconv -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
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461@end example
462will create an output WAV file tagged as stereo from the downmix channels of
463the input.
464
465To fix a 5.1 WAV improperly encoded in AAC's native channel order
466@example
ba8efac9 467avconv -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav
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468@end example
469
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470@section compand
471Compress or expand audio dynamic range.
472
473A description of the accepted options follows.
474
475@table @option
476
477@item attacks
478@item decays
479Set list of times in seconds for each channel over which the instantaneous level
480of the input signal is averaged to determine its volume. @var{attacks} refers to
481increase of volume and @var{decays} refers to decrease of volume. For most
482situations, the attack time (response to the audio getting louder) should be
483shorter than the decay time because the human ear is more sensitive to sudden
484loud audio than sudden soft audio. A typical value for attack is 0.3 seconds and
485a typical value for decay is 0.8 seconds.
486
487@item points
488Set list of points for the transfer function, specified in dB relative to the
489maximum possible signal amplitude. Each key points list must be defined using
490the following syntax: @code{x0/y0|x1/y1|x2/y2|....}
491
492The input values must be in strictly increasing order but the transfer function
493does not have to be monotonically rising. The point @code{0/0} is assumed but
494may be overridden (by @code{0/out-dBn}). Typical values for the transfer
495function are @code{-70/-70|-60/-20}.
496
497@item soft-knee
498Set the curve radius in dB for all joints. Defaults to 0.01.
499
500@item gain
501Set additional gain in dB to be applied at all points on the transfer function.
502This allows easy adjustment of the overall gain. Defaults to 0.
503
504@item volume
505Set initial volume in dB to be assumed for each channel when filtering starts.
506This permits the user to supply a nominal level initially, so that, for
507example, a very large gain is not applied to initial signal levels before the
508companding has begun to operate. A typical value for audio which is initially
509quiet is -90 dB. Defaults to 0.
510
511@item delay
512Set delay in seconds. The input audio is analyzed immediately, but audio is
513delayed before being fed to the volume adjuster. Specifying a delay
514approximately equal to the attack/decay times allows the filter to effectively
515operate in predictive rather than reactive mode. Defaults to 0.
516
517@end table
518
519@subsection Examples
520
521@itemize
522@item
523Make music with both quiet and loud passages suitable for listening in a noisy
524environment:
525@example
526compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2
527@end example
528
529@item
530Noise gate for when the noise is at a lower level than the signal:
531@example
532compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1
533@end example
534
535@item
536Here is another noise gate, this time for when the noise is at a higher level
537than the signal (making it, in some ways, similar to squelch):
538@example
539compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1
540@end example
541@end itemize
542
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543@section join
544Join multiple input streams into one multi-channel stream.
545
546The filter accepts the following named parameters:
547@table @option
548
549@item inputs
550Number of input streams. Defaults to 2.
551
552@item channel_layout
553Desired output channel layout. Defaults to stereo.
554
555@item map
dd7fc37c 556Map channels from inputs to output. The argument is a '|'-separated list of
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557mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}}
558form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel}
7a8059eb 559can be either the name of the input channel (e.g. FL for front left) or its
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560index in the specified input stream. @var{out_channel} is the name of the output
561channel.
562@end table
563
564The filter will attempt to guess the mappings when those are not specified
565explicitly. It does so by first trying to find an unused matching input channel
566and if that fails it picks the first unused input channel.
567
568E.g. to join 3 inputs (with properly set channel layouts)
569@example
570avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
571@end example
572
573To build a 5.1 output from 6 single-channel streams:
574@example
575avconv -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
dd7fc37c 576'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'
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577out
578@end example
579
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580@section resample
581Convert the audio sample format, sample rate and channel layout. This filter is
582not meant to be used directly, it is inserted automatically by libavfilter
583whenever conversion is needed. Use the @var{aformat} filter to force a specific
584conversion.
585
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586@section volume
587
588Adjust the input audio volume.
589
590The filter accepts the following named parameters:
591@table @option
592
593@item volume
594Expresses how the audio volume will be increased or decreased.
595
596Output values are clipped to the maximum value.
597
598The output audio volume is given by the relation:
599@example
600@var{output_volume} = @var{volume} * @var{input_volume}
601@end example
602
603Default value for @var{volume} is 1.0.
604
605@item precision
606Mathematical precision.
607
608This determines which input sample formats will be allowed, which affects the
609precision of the volume scaling.
610
611@table @option
612@item fixed
6138-bit fixed-point; limits input sample format to U8, S16, and S32.
614@item float
61532-bit floating-point; limits input sample format to FLT. (default)
616@item double
61764-bit floating-point; limits input sample format to DBL.
618@end table
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619
620@item replaygain
621Behaviour on encountering ReplayGain side data in input frames.
622
623@table @option
624@item drop
625Remove ReplayGain side data, ignoring its contents (the default).
626
627@item ignore
628Ignore ReplayGain side data, but leave it in the frame.
629
630@item track
631Prefer track gain, if present.
632
633@item album
634Prefer album gain, if present.
635@end table
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636@end table
637
638@subsection Examples
639
640@itemize
641@item
642Halve the input audio volume:
643@example
644volume=volume=0.5
645volume=volume=1/2
646volume=volume=-6.0206dB
647@end example
648
649@item
650Increase input audio power by 6 decibels using fixed-point precision:
651@example
652volume=volume=6dB:precision=fixed
653@end example
654@end itemize
655
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656@c man end AUDIO FILTERS
657
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658@chapter Audio Sources
659@c man begin AUDIO SOURCES
660
661Below is a description of the currently available audio sources.
662
663@section anullsrc
664
665Null audio source, never return audio frames. It is mainly useful as a
666template and to be employed in analysis / debugging tools.
667
668It accepts as optional parameter a string of the form
669@var{sample_rate}:@var{channel_layout}.
670
671@var{sample_rate} specify the sample rate, and defaults to 44100.
672
673@var{channel_layout} specify the channel layout, and can be either an
674integer or a string representing a channel layout. The default value
675of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
676
677Check the channel_layout_map definition in
a903f8f0 678@file{libavutil/channel_layout.c} for the mapping between strings and
6ef93402 679channel layout values.
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680
681Follow some examples:
682@example
683# set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
684anullsrc=48000:4
685
686# same as
687anullsrc=48000:mono
688@end example
689
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690@section abuffer
691Buffer audio frames, and make them available to the filter chain.
692
693This source is not intended to be part of user-supplied graph descriptions but
694for insertion by calling programs through the interface defined in
695@file{libavfilter/buffersrc.h}.
696
697It accepts the following named parameters:
698@table @option
699
700@item time_base
701Timebase which will be used for timestamps of submitted frames. It must be
702either a floating-point number or in @var{numerator}/@var{denominator} form.
703
704@item sample_rate
705Audio sample rate.
706
707@item sample_fmt
708Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
709
710@item channel_layout
711Channel layout of the audio data, in the form that can be accepted by
712@code{av_get_channel_layout()}.
713@end table
714
715All the parameters need to be explicitly defined.
716
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717@c man end AUDIO SOURCES
718
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719@chapter Audio Sinks
720@c man begin AUDIO SINKS
721
722Below is a description of the currently available audio sinks.
723
724@section anullsink
725
726Null audio sink, do absolutely nothing with the input audio. It is
727mainly useful as a template and to be employed in analysis / debugging
728tools.
729
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730@section abuffersink
731This sink is intended for programmatic use. Frames that arrive on this sink can
732be retrieved by the calling program using the interface defined in
733@file{libavfilter/buffersink.h}.
734
735This filter accepts no parameters.
736
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737@c man end AUDIO SINKS
738
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739@chapter Video Filters
740@c man begin VIDEO FILTERS
741
f8a45fa1 742When you configure your Libav build, you can disable any of the
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743existing filters using --disable-filters.
744The configure output will show the video filters included in your
745build.
746
747Below is a description of the currently available video filters.
748
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749@section blackframe
750
751Detect frames that are (almost) completely black. Can be useful to
752detect chapter transitions or commercials. Output lines consist of
753the frame number of the detected frame, the percentage of blackness,
754the position in the file if known or -1 and the timestamp in seconds.
755
756In order to display the output lines, you need to set the loglevel at
757least to the AV_LOG_INFO value.
758
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759The filter accepts the following options:
760
761@table @option
762
763@item amount
764The percentage of the pixels that have to be below the threshold, defaults to
76598.
13fabd7a 766
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767@item threshold
768Threshold below which a pixel value is considered black, defaults to 32.
13fabd7a 769
62dcdb02 770@end table
13fabd7a 771
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772@section boxblur
773
774Apply boxblur algorithm to the input video.
775
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776This filter accepts the following options:
777
778@table @option
779
780@item luma_radius
781@item luma_power
782@item chroma_radius
783@item chroma_power
784@item alpha_radius
785@item alpha_power
786
787@end table
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788
789Chroma and alpha parameters are optional, if not specified they default
790to the corresponding values set for @var{luma_radius} and
791@var{luma_power}.
792
793@var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
794the radius in pixels of the box used for blurring the corresponding
795input plane. They are expressions, and can contain the following
796constants:
797@table @option
798@item w, h
da9cea77 799the input width and height in pixels
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800
801@item cw, ch
802the input chroma image width and height in pixels
803
804@item hsub, vsub
805horizontal and vertical chroma subsample values. For example for the
806pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
807@end table
808
809The radius must be a non-negative number, and must not be greater than
810the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
811and of @code{min(cw,ch)/2} for the chroma planes.
812
813@var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
814how many times the boxblur filter is applied to the corresponding
815plane.
816
817Some examples follow:
818
819@itemize
820
821@item
822Apply a boxblur filter with luma, chroma, and alpha radius
823set to 2:
824@example
51def31d 825boxblur=luma_radius=2:luma_power=1
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826@end example
827
828@item
829Set luma radius to 2, alpha and chroma radius to 0
830@example
831boxblur=2:1:0:0:0:0
832@end example
833
834@item
835Set luma and chroma radius to a fraction of the video dimension
836@example
51def31d 837boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
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838@end example
839
840@end itemize
841
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842@section copy
843
844Copy the input source unchanged to the output. Mainly useful for
845testing purposes.
846
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847@section crop
848
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849Crop the input video to given dimensions.
850
851This filter accepts the following options:
852
853@table @option
854
855@item out_w
856Width of the output video.
857
858@item out_h
859Height of the output video.
860
861@item x
862Horizontal position, in the input video, of the left edge of the output video.
863
864@item y
865Vertical position, in the input video, of the top edge of the output video.
866
867@end table
3275ac6a 868
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869The parameters are expressions containing the following constants:
870
871@table @option
872@item E, PI, PHI
873the corresponding mathematical approximated values for e
874(euler number), pi (greek PI), PHI (golden ratio)
875
876@item x, y
877the computed values for @var{x} and @var{y}. They are evaluated for
878each new frame.
879
880@item in_w, in_h
e83c2dde 881the input width and height
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882
883@item iw, ih
884same as @var{in_w} and @var{in_h}
885
886@item out_w, out_h
e83c2dde 887the output (cropped) width and height
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888
889@item ow, oh
890same as @var{out_w} and @var{out_h}
891
892@item n
893the number of input frame, starting from 0
894
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895@item t
896timestamp expressed in seconds, NAN if the input timestamp is unknown
3275ac6a 897
75b67a8a 898@end table
3275ac6a 899
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900The @var{out_w} and @var{out_h} parameters specify the expressions for
901the width and height of the output (cropped) video. They are
902evaluated just at the configuration of the filter.
3275ac6a 903
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904The default value of @var{out_w} is "in_w", and the default value of
905@var{out_h} is "in_h".
2bc05d35 906
75b67a8a
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907The expression for @var{out_w} may depend on the value of @var{out_h},
908and the expression for @var{out_h} may depend on @var{out_w}, but they
909cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
910evaluated after @var{out_w} and @var{out_h}.
2bc05d35 911
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912The @var{x} and @var{y} parameters specify the expressions for the
913position of the top-left corner of the output (non-cropped) area. They
914are evaluated for each frame. If the evaluated value is not valid, it
915is approximated to the nearest valid value.
3275ac6a 916
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917The default value of @var{x} is "(in_w-out_w)/2", and the default
918value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
919the center of the input image.
920
921The expression for @var{x} may depend on @var{y}, and the expression
922for @var{y} may depend on @var{x}.
923
924Follow some examples:
3275ac6a 925@example
75b67a8a 926# crop the central input area with size 100x100
fba0156a 927crop=out_w=100:out_h=100
75b67a8a
SS
928
929# crop the central input area with size 2/3 of the input video
fba0156a 930"crop=out_w=2/3*in_w:out_h=2/3*in_h"
75b67a8a
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931
932# crop the input video central square
fba0156a 933crop=out_w=in_h
75b67a8a
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934
935# delimit the rectangle with the top-left corner placed at position
936# 100:100 and the right-bottom corner corresponding to the right-bottom
937# corner of the input image.
fba0156a 938crop=out_w=in_w-100:out_h=in_h-100:x=100:y=100
3275ac6a 939
e6dba1d8 940# crop 10 pixels from the left and right borders, and 20 pixels from
75b67a8a 941# the top and bottom borders
fba0156a 942"crop=out_w=in_w-2*10:out_h=in_h-2*20"
3275ac6a 943
75b67a8a 944# keep only the bottom right quarter of the input image
fba0156a 945"crop=out_w=in_w/2:out_h=in_h/2:x=in_w/2:y=in_h/2"
75b67a8a
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946
947# crop height for getting Greek harmony
fba0156a 948"crop=out_w=in_w:out_h=1/PHI*in_w"
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949
950# trembling effect
951"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)"
952
e6dba1d8 953# erratic camera effect depending on timestamp
fba0156a 954"crop=out_w=in_w/2:out_h=in_h/2:x=(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):y=(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
75b67a8a
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955
956# set x depending on the value of y
957"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
958@end example
3275ac6a 959
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960@section cropdetect
961
962Auto-detect crop size.
963
964Calculate necessary cropping parameters and prints the recommended
965parameters through the logging system. The detected dimensions
966correspond to the non-black area of the input video.
967
460e7b4f 968This filter accepts the following options:
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969
970@table @option
971
972@item limit
973Threshold, which can be optionally specified from nothing (0) to
974everything (255), defaults to 24.
975
976@item round
977Value which the width/height should be divisible by, defaults to
97816. The offset is automatically adjusted to center the video. Use 2 to
979get only even dimensions (needed for 4:2:2 video). 16 is best when
980encoding to most video codecs.
981
982@item reset
983Counter that determines after how many frames cropdetect will reset
984the previously detected largest video area and start over to detect
985the current optimal crop area. Defaults to 0.
986
987This can be useful when channel logos distort the video area. 0
988indicates never reset and return the largest area encountered during
989playback.
990@end table
991
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992@section delogo
993
994Suppress a TV station logo by a simple interpolation of the surrounding
995pixels. Just set a rectangle covering the logo and watch it disappear
996(and sometimes something even uglier appear - your mileage may vary).
997
63e58c55 998This filter accepts the following options:
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999@table @option
1000
1001@item x, y
1002Specify the top left corner coordinates of the logo. They must be
1003specified.
1004
1005@item w, h
1006Specify the width and height of the logo to clear. They must be
1007specified.
1008
1009@item band, t
1010Specify the thickness of the fuzzy edge of the rectangle (added to
1011@var{w} and @var{h}). The default value is 4.
1012
1013@item show
1014When set to 1, a green rectangle is drawn on the screen to simplify
1015finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1016@var{band} is set to 4. The default value is 0.
1017
1018@end table
1019
1020Some examples follow.
1021
1022@itemize
1023
1024@item
1025Set a rectangle covering the area with top left corner coordinates 0,0
1026and size 100x77, setting a band of size 10:
1027@example
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SS
1028delogo=x=0:y=0:w=100:h=77:band=10
1029@end example
1030
1031@end itemize
1032
e40032e2
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1033@section drawbox
1034
1035Draw a colored box on the input image.
1036
335c3129 1037This filter accepts the following options:
e40032e2
SS
1038
1039@table @option
1040
1041@item x, y
1042Specify the top left corner coordinates of the box. Default to 0.
1043
1044@item width, height
1045Specify the width and height of the box, if 0 they are interpreted as
1046the input width and height. Default to 0.
1047
1048@item color
1049Specify the color of the box to write, it can be the name of a color
1050(case insensitive match) or a 0xRRGGBB[AA] sequence.
1051@end table
1052
1053Follow some examples:
1054@example
1055# draw a black box around the edge of the input image
1056drawbox
1057
1058# draw a box with color red and an opacity of 50%
335c3129 1059drawbox=x=10:y=20:width=200:height=60:color=red@@0.5"
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SS
1060@end example
1061
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1062@section drawtext
1063
1064Draw text string or text from specified file on top of video using the
1065libfreetype library.
1066
0c50edb7 1067To enable compilation of this filter you need to configure Libav with
a5b64584
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1068@code{--enable-libfreetype}.
1069
1070The filter also recognizes strftime() sequences in the provided text
1071and expands them accordingly. Check the documentation of strftime().
1072
a5b64584
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1073The description of the accepted parameters follows.
1074
1075@table @option
1076
1077@item fontfile
1078The font file to be used for drawing text. Path must be included.
1079This parameter is mandatory.
1080
1081@item text
1082The text string to be drawn. The text must be a sequence of UTF-8
1083encoded characters.
1084This parameter is mandatory if no file is specified with the parameter
1085@var{textfile}.
1086
1087@item textfile
1088A text file containing text to be drawn. The text must be a sequence
1089of UTF-8 encoded characters.
1090
1091This parameter is mandatory if no text string is specified with the
1092parameter @var{text}.
1093
1094If both text and textfile are specified, an error is thrown.
1095
1096@item x, y
1097The offsets where text will be drawn within the video frame.
1098Relative to the top/left border of the output image.
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LB
1099They accept expressions similar to the @ref{overlay} filter:
1100@table @option
1101
1102@item x, y
1103the computed values for @var{x} and @var{y}. They are evaluated for
1104each new frame.
1105
1106@item main_w, main_h
1107main input width and height
1108
1109@item W, H
1110same as @var{main_w} and @var{main_h}
1111
1112@item text_w, text_h
1113rendered text width and height
1114
1115@item w, h
1116same as @var{text_w} and @var{text_h}
1117
1118@item n
1119the number of frames processed, starting from 0
1120
1121@item t
1122timestamp expressed in seconds, NAN if the input timestamp is unknown
1123
1124@end table
a5b64584
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1125
1126The default value of @var{x} and @var{y} is 0.
1127
1128@item fontsize
1129The font size to be used for drawing text.
1130The default value of @var{fontsize} is 16.
1131
1132@item fontcolor
1133The color to be used for drawing fonts.
1134Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1135(e.g. "0xff000033"), possibly followed by an alpha specifier.
1136The default value of @var{fontcolor} is "black".
1137
1138@item boxcolor
1139The color to be used for drawing box around text.
1140Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1141(e.g. "0xff00ff"), possibly followed by an alpha specifier.
1142The default value of @var{boxcolor} is "white".
1143
1144@item box
1145Used to draw a box around text using background color.
1146Value should be either 1 (enable) or 0 (disable).
1147The default value of @var{box} is 0.
1148
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SS
1149@item shadowx, shadowy
1150The x and y offsets for the text shadow position with respect to the
1151position of the text. They can be either positive or negative
1152values. Default value for both is "0".
1153
1154@item shadowcolor
1155The color to be used for drawing a shadow behind the drawn text. It
1156can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1157form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1158The default value of @var{shadowcolor} is "black".
1159
a5b64584
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1160@item ft_load_flags
1161Flags to be used for loading the fonts.
1162
1163The flags map the corresponding flags supported by libfreetype, and are
1164a combination of the following values:
1165@table @var
1166@item default
1167@item no_scale
1168@item no_hinting
1169@item render
1170@item no_bitmap
1171@item vertical_layout
1172@item force_autohint
1173@item crop_bitmap
1174@item pedantic
1175@item ignore_global_advance_width
1176@item no_recurse
1177@item ignore_transform
1178@item monochrome
1179@item linear_design
1180@item no_autohint
1181@item end table
1182@end table
1183
1184Default value is "render".
1185
1186For more information consult the documentation for the FT_LOAD_*
1187libfreetype flags.
1188
1189@item tabsize
1190The size in number of spaces to use for rendering the tab.
1191Default value is 4.
e496c45d
AU
1192
1193@item fix_bounds
1194If true, check and fix text coords to avoid clipping.
a5b64584
SS
1195@end table
1196
1197For example the command:
1198@example
1199drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1200@end example
1201
1202will draw "Test Text" with font FreeSerif, using the default values
1203for the optional parameters.
1204
1205The command:
1206@example
1207drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1208 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1209@end example
1210
1211will draw 'Test Text' with font FreeSerif of size 24 at position x=100
1212and y=50 (counting from the top-left corner of the screen), text is
1213yellow with a red box around it. Both the text and the box have an
1214opacity of 20%.
1215
1216Note that the double quotes are not necessary if spaces are not used
1217within the parameter list.
1218
1219For more information about libfreetype, check:
1220@url{http://www.freetype.org/}.
1221
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1222@section fade
1223
1224Apply fade-in/out effect to input video.
1225
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1226This filter accepts the following options:
1227
1228@table @option
aadfc9ee 1229
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1230@item type
1231The effect type -- can be either "in" for fade-in, or "out" for a fade-out
1232effect.
aadfc9ee 1233
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1234@item start_frame
1235The number of the start frame for starting to apply the fade effect.
aadfc9ee 1236
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1237@item nb_frames
1238The number of frames for which the fade effect has to last. At the end of the
1239fade-in effect the output video will have the same intensity as the input video,
1240at the end of the fade-out transition the output video will be completely black.
1241
1242@end table
aadfc9ee
BM
1243
1244A few usage examples follow, usable too as test scenarios.
1245@example
1246# fade in first 30 frames of video
b9dfee9f 1247fade=type=in:nb_frames=30
aadfc9ee
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1248
1249# fade out last 45 frames of a 200-frame video
b9dfee9f 1250fade=type=out:start_frame=155:nb_frames=45
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1251
1252# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
b9dfee9f 1253fade=type=in:start_frame=0:nb_frames=25, fade=type=out:start_frame=975:nb_frames=25
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1254
1255# make first 5 frames black, then fade in from frame 5-24
b9dfee9f 1256fade=type=in:start_frame=5:nb_frames=20
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BM
1257@end example
1258
2f84bb42
MH
1259@section fieldorder
1260
1261Transform the field order of the input video.
1262
a39c1540 1263This filter accepts the following options:
2f84bb42
MH
1264
1265@table @option
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AK
1266
1267@item order
1268Output field order. Valid values are @var{tff} for top field first or @var{bff}
1269for bottom field first.
2f84bb42
MH
1270@end table
1271
1272Default value is "tff".
1273
1274Transformation is achieved by shifting the picture content up or down
1275by one line, and filling the remaining line with appropriate picture content.
1276This method is consistent with most broadcast field order converters.
1277
1278If the input video is not flagged as being interlaced, or it is already
1279flagged as being of the required output field order then this filter does
1280not alter the incoming video.
1281
1282This filter is very useful when converting to or from PAL DV material,
1283which is bottom field first.
1284
1285For example:
1286@example
a39c1540 1287./avconv -i in.vob -vf "fieldorder=order=bff" out.dv
2f84bb42
MH
1288@end example
1289
7f1af825
SS
1290@section fifo
1291
1292Buffer input images and send them when they are requested.
1293
1294This filter is mainly useful when auto-inserted by the libavfilter
1295framework.
1296
1297The filter does not take parameters.
1298
3275ac6a
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1299@section format
1300
1301Convert the input video to one of the specified pixel formats.
1302Libavfilter will try to pick one that is supported for the input to
1303the next filter.
1304
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1305This filter accepts the following parameters:
1306@table @option
1307
1308@item pix_fmts
1309A '|'-separated list of pixel format names, for example
1310"pix_fmts=yuv420p|monow|rgb24".
1311
1312@end table
3275ac6a 1313
f150e4dc 1314Some examples follow:
3275ac6a 1315@example
f150e4dc 1316# convert the input video to the format "yuv420p"
e67a87ea 1317format=pix_fmts=yuv420p
3275ac6a 1318
f150e4dc 1319# convert the input video to any of the formats in the list
e67a87ea 1320format=pix_fmts=yuv420p|yuv444p|yuv410p
f150e4dc 1321@end example
3275ac6a 1322
dd249245 1323@anchor{fps}
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1324@section fps
1325
1326Convert the video to specified constant framerate by duplicating or dropping
1327frames as necessary.
1328
1329This filter accepts the following named parameters:
1330@table @option
1331
1332@item fps
1333Desired output framerate.
1334
545a0b80
JR
1335@item start_time
1336Assume the first PTS should be the given value, in seconds. This allows for
1337padding/trimming at the start of stream. By default, no assumption is made
1338about the first frame's expected PTS, so no padding or trimming is done.
1339For example, this could be set to 0 to pad the beginning with duplicates of
1340the first frame if a video stream starts after the audio stream or to trim any
1341frames with a negative PTS.
1342
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1343@end table
1344
a7d0e7ea
VG
1345@section framepack
1346
1347Pack two different video streams into a stereoscopic video, setting proper
1348metadata on supported codecs. The two views should have the same size and
1349framerate and processing will stop when the shorter video ends. Please note
1350that you may conveniently adjust view properties with the @ref{scale} and
1351@ref{fps} filters.
1352
1353This filter accepts the following named parameters:
1354@table @option
1355
1356@item format
1357Desired packing format. Supported values are:
1358
1359@table @option
1360
1361@item sbs
1362Views are next to each other (default).
1363
1364@item tab
1365Views are on top of each other.
1366
1367@item lines
1368Views are packed by line.
1369
1370@item columns
1371Views are eacked by column.
1372
1373@item frameseq
1374Views are temporally interleaved.
1375
1376@end table
1377
1378@end table
1379
1380Some examples follow:
1381
1382@example
1383# Convert left and right views into a frame sequential video.
1384avconv -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
1385
1386# Convert views into a side-by-side video with the same output resolution as the input.
1387avconv -i LEFT -i RIGHT -filter_complex [0:v]scale=w=iw/2[left],[1:v]scale=w=iw/2[right],[left][right]framepack=sbs OUTPUT
1388@end example
1389
f8608dca 1390@anchor{frei0r}
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1391@section frei0r
1392
1393Apply a frei0r effect to the input video.
1394
1395To enable compilation of this filter you need to install the frei0r
f8a45fa1 1396header and configure Libav with --enable-frei0r.
47941088 1397
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1398This filter accepts the following options:
1399
1400@table @option
1401
1402@item filter_name
1403The name to the frei0r effect to load. If the environment variable
1404@env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
1405directories specified by the colon separated list in @env{FREIOR_PATH},
1406otherwise in the standard frei0r paths, which are in this order:
1407@file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
1408@file{/usr/lib/frei0r-1/}.
47941088 1409
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1410@item filter_params
1411A '|'-separated list of parameters to pass to the frei0r effect.
47941088 1412
5aa1a668 1413@end table
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1414
1415A frei0r effect parameter can be a boolean (whose values are specified
1416with "y" and "n"), a double, a color (specified by the syntax
1417@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1418numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1419description), a position (specified by the syntax @var{X}/@var{Y},
1420@var{X} and @var{Y} being float numbers) and a string.
1421
1422The number and kind of parameters depend on the loaded effect. If an
1423effect parameter is not specified the default value is set.
1424
1425Some examples follow:
1426@example
1427# apply the distort0r effect, set the first two double parameters
5aa1a668 1428frei0r=filter_name=distort0r:filter_params=0.5|0.01
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1429
1430# apply the colordistance effect, takes a color as first parameter
1431frei0r=colordistance:0.2/0.3/0.4
1432frei0r=colordistance:violet
1433frei0r=colordistance:0x112233
1434
1435# apply the perspective effect, specify the top left and top right
1436# image positions
5aa1a668 1437frei0r=perspective:0.2/0.2|0.8/0.2
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1438@end example
1439
1440For more information see:
1441@url{http://piksel.org/frei0r}
1442
d5f187fd
N
1443@section gradfun
1444
1445Fix the banding artifacts that are sometimes introduced into nearly flat
1446regions by truncation to 8bit colordepth.
1447Interpolate the gradients that should go where the bands are, and
1448dither them.
1449
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1450This filter is designed for playback only. Do not use it prior to
1451lossy compression, because compression tends to lose the dither and
1452bring back the bands.
1453
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1454This filter accepts the following options:
1455
1456@table @option
d5f187fd 1457
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1458@item strength
1459The maximum amount by which the filter will change any one pixel. Also the
1460threshold for detecting nearly flat regions. Acceptable values range from .51 to
146164, default value is 1.2, out-of-range values will be clipped to the valid
1462range.
d5f187fd 1463
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1464@item radius
1465The neighborhood to fit the gradient to. A larger radius makes for smoother
1466gradients, but also prevents the filter from modifying the pixels near detailed
1467regions. Acceptable values are 8-32, default value is 16, out-of-range values
1468will be clipped to the valid range.
1469
1470@end table
d5f187fd
N
1471
1472@example
1473# default parameters
7ed833d7 1474gradfun=strength=1.2:radius=16
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N
1475
1476# omitting radius
1477gradfun=1.2
1478@end example
1479
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1480@section hflip
1481
1482Flip the input video horizontally.
1483
9270b8a3 1484For example to horizontally flip the input video with @command{avconv}:
a1e171df 1485@example
9270b8a3 1486avconv -i in.avi -vf "hflip" out.avi
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1487@end example
1488
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1489@section hqdn3d
1490
1491High precision/quality 3d denoise filter. This filter aims to reduce
1492image noise producing smooth images and making still images really
1493still. It should enhance compressibility.
1494
1495It accepts the following optional parameters:
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1496
1497@table @option
1498@item luma_spatial
1499a non-negative float number which specifies spatial luma strength,
1500defaults to 4.0
1501
1502@item chroma_spatial
1503a non-negative float number which specifies spatial chroma strength,
1504defaults to 3.0*@var{luma_spatial}/4.0
1505
1506@item luma_tmp
1507a float number which specifies luma temporal strength, defaults to
15086.0*@var{luma_spatial}/4.0
1509
1510@item chroma_tmp
1511a float number which specifies chroma temporal strength, defaults to
1512@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1513@end table
1514
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1515@section interlace
1516
1517Simple interlacing filter from progressive contents. This interleaves upper (or
1518lower) lines from odd frames with lower (or upper) lines from even frames,
35b05c51 1519halving the frame rate and preserving image height. A vertical lowpass filter
c91488ab 1520is always applied in order to avoid twitter effects and reduce moiré patterns.
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1521
1522@example
1523 Original Original New Frame
1524 Frame 'j' Frame 'j+1' (tff)
1525 ========== =========== ==================
1526 Line 0 --------------------> Frame 'j' Line 0
1527 Line 1 Line 1 ----> Frame 'j+1' Line 1
1528 Line 2 ---------------------> Frame 'j' Line 2
1529 Line 3 Line 3 ----> Frame 'j+1' Line 3
1530 ... ... ...
1531New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
1532@end example
1533
1534It accepts the following optional parameters:
1535
1536@table @option
1537@item scan
1538determines whether the interlaced frame is taken from the even (tff - default)
1539or odd (bff) lines of the progressive frame.
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VG
1540@end table
1541
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1542@section lut, lutrgb, lutyuv
1543
1544Compute a look-up table for binding each pixel component input value
1545to an output value, and apply it to input video.
1546
1547@var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1548to an RGB input video.
1549
20b46f8f 1550These filters accept the following options:
8fe0c527 1551@table @option
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1552@item @var{c0} (first pixel component)
1553@item @var{c1} (second pixel component)
1554@item @var{c2} (third pixel component)
1555@item @var{c3} (fourth pixel component, corresponds to the alpha component)
8fe0c527 1556
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1557@item @var{r} (red component)
1558@item @var{g} (green component)
1559@item @var{b} (blue component)
1560@item @var{a} (alpha component)
8fe0c527 1561
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1562@item @var{y} (Y/luminance component)
1563@item @var{u} (U/Cb component)
1564@item @var{v} (V/Cr component)
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1565@end table
1566
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1567Each of them specifies the expression to use for computing the lookup table for
1568the corresponding pixel component values.
1569
1570The exact component associated to each of the @var{c*} options depends on the
1571format in input.
1572
1573The @var{lut} filter requires either YUV or RGB pixel formats in input,
1574@var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
1575
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1576The expressions can contain the following constants and functions:
1577
1578@table @option
1579@item E, PI, PHI
1580the corresponding mathematical approximated values for e
1581(euler number), pi (greek PI), PHI (golden ratio)
1582
1583@item w, h
da9cea77 1584the input width and height
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1585
1586@item val
1587input value for the pixel component
1588
1589@item clipval
1590the input value clipped in the @var{minval}-@var{maxval} range
1591
1592@item maxval
1593maximum value for the pixel component
1594
1595@item minval
1596minimum value for the pixel component
1597
1598@item negval
1599the negated value for the pixel component value clipped in the
1600@var{minval}-@var{maxval} range , it corresponds to the expression
1601"maxval-clipval+minval"
1602
1603@item clip(val)
1604the computed value in @var{val} clipped in the
1605@var{minval}-@var{maxval} range
1606
1607@item gammaval(gamma)
1608the computed gamma correction value of the pixel component value
1609clipped in the @var{minval}-@var{maxval} range, corresponds to the
1610expression
1611"pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1612
1613@end table
1614
1615All expressions default to "val".
1616
1617Some examples follow:
1618@example
1619# negate input video
1620lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1621lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1622
1623# the above is the same as
1624lutrgb="r=negval:g=negval:b=negval"
1625lutyuv="y=negval:u=negval:v=negval"
1626
1627# negate luminance
1628lutyuv=negval
1629
1630# remove chroma components, turns the video into a graytone image
1631lutyuv="u=128:v=128"
1632
1633# apply a luma burning effect
1634lutyuv="y=2*val"
1635
1636# remove green and blue components
1637lutrgb="g=0:b=0"
1638
1639# set a constant alpha channel value on input
1640format=rgba,lutrgb=a="maxval-minval/2"
1641
1642# correct luminance gamma by a 0.5 factor
1643lutyuv=y=gammaval(0.5)
1644@end example
1645
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1646@section negate
1647
1648Negate input video.
1649
1650This filter accepts an integer in input, if non-zero it negates the
1651alpha component (if available). The default value in input is 0.
3275ac6a 1652
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1653@section noformat
1654
3275ac6a
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1655Force libavfilter not to use any of the specified pixel formats for the
1656input to the next filter.
1657
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1658This filter accepts the following parameters:
1659@table @option
1660
1661@item pix_fmts
1662A '|'-separated list of pixel format names, for example
1663"pix_fmts=yuv420p|monow|rgb24".
1664
1665@end table
3275ac6a 1666
f150e4dc 1667Some examples follow:
3275ac6a 1668@example
f150e4dc
SS
1669# force libavfilter to use a format different from "yuv420p" for the
1670# input to the vflip filter
e67a87ea 1671noformat=pix_fmts=yuv420p,vflip
3275ac6a 1672
f150e4dc 1673# convert the input video to any of the formats not contained in the list
e67a87ea 1674noformat=yuv420p|yuv444p|yuv410p
f150e4dc 1675@end example
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1676
1677@section null
1678
99046339 1679Pass the video source unchanged to the output.
3275ac6a 1680
cf69ad35 1681@section ocv
6ebf0bfc 1682
cf69ad35 1683Apply video transform using libopencv.
6ebf0bfc
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1684
1685To enable this filter install libopencv library and headers and
f8a45fa1 1686configure Libav with --enable-libopencv.
6ebf0bfc 1687
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1688This filter accepts the following parameters:
1689
1690@table @option
cf69ad35 1691
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1692@item filter_name
1693The name of the libopencv filter to apply.
cf69ad35 1694
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1695@item filter_params
1696The parameters to pass to the libopencv filter. If not specified the default
1697values are assumed.
1698
1699@end table
cf69ad35
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1700
1701Refer to the official libopencv documentation for more precise
da9cea77 1702information:
cf69ad35
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1703@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1704
1705Follows the list of supported libopencv filters.
1706
17fc9493 1707@anchor{dilate}
91cbb6ba
SS
1708@subsection dilate
1709
1710Dilate an image by using a specific structuring element.
1711This filter corresponds to the libopencv function @code{cvDilate}.
1712
ee0e8d4b 1713It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
91cbb6ba
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1714
1715@var{struct_el} represents a structuring element, and has the syntax:
1716@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1717
da9cea77 1718@var{cols} and @var{rows} represent the number of columns and rows of
91cbb6ba
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1719the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1720point, and @var{shape} the shape for the structuring element, and
1721can be one of the values "rect", "cross", "ellipse", "custom".
1722
1723If the value for @var{shape} is "custom", it must be followed by a
1724string of the form "=@var{filename}". The file with name
1725@var{filename} is assumed to represent a binary image, with each
1726printable character corresponding to a bright pixel. When a custom
1727@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1728or columns and rows of the read file are assumed instead.
1729
1730The default value for @var{struct_el} is "3x3+0x0/rect".
1731
1732@var{nb_iterations} specifies the number of times the transform is
1733applied to the image, and defaults to 1.
1734
1735Follow some example:
1736@example
1737# use the default values
1738ocv=dilate
1739
1740# dilate using a structuring element with a 5x5 cross, iterate two times
ee0e8d4b 1741ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
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1742
1743# read the shape from the file diamond.shape, iterate two times
1744# the file diamond.shape may contain a pattern of characters like this:
1745# *
1746# ***
1747# *****
1748# ***
1749# *
1750# the specified cols and rows are ignored (but not the anchor point coordinates)
ee0e8d4b 1751ocv=dilate:0x0+2x2/custom=diamond.shape|2
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1752@end example
1753
17fc9493
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1754@subsection erode
1755
1756Erode an image by using a specific structuring element.
1757This filter corresponds to the libopencv function @code{cvErode}.
1758
1759The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4c989761 1760with the same syntax and semantics as the @ref{dilate} filter.
17fc9493 1761
cf69ad35
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1762@subsection smooth
1763
1764Smooth the input video.
1765
1766The filter takes the following parameters:
ee0e8d4b 1767@var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
6ebf0bfc
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1768
1769@var{type} is the type of smooth filter to apply, and can be one of
58d94364 1770the following values: "blur", "blur_no_scale", "median", "gaussian",
6ebf0bfc
SS
1771"bilateral". The default value is "gaussian".
1772
1773@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1774parameters whose meanings depend on smooth type. @var{param1} and
1775@var{param2} accept integer positive values or 0, @var{param3} and
1776@var{param4} accept float values.
1777
1778The default value for @var{param1} is 3, the default value for the
1779other parameters is 0.
1780
58d94364 1781These parameters correspond to the parameters assigned to the
cf69ad35 1782libopencv function @code{cvSmooth}.
6ebf0bfc 1783
2cf74eca 1784@anchor{overlay}
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1785@section overlay
1786
1787Overlay one video on top of another.
1788
1789It takes two inputs and one output, the first input is the "main"
1790video on which the second input is overlayed.
1791
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1792This filter accepts the following parameters:
1793
1794@table @option
1795
1796@item x
1797The horizontal position of the left edge of the overlaid video on the main video.
1798
1799@item y
1800The vertical position of the top edge of the overlaid video on the main video.
1801
1802@end table
58935b25 1803
9087eaf1 1804The parameters are expressions containing the following parameters:
58935b25
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1805
1806@table @option
1807@item main_w, main_h
1808main input width and height
1809
1810@item W, H
1811same as @var{main_w} and @var{main_h}
1812
1813@item overlay_w, overlay_h
1814overlay input width and height
1815
1816@item w, h
1817same as @var{overlay_w} and @var{overlay_h}
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1818
1819@item eof_action
1820The action to take when EOF is encountered on the secondary input, accepts one
1821of the following values:
1822
1823@table @option
1824@item repeat
1825repeat the last frame (the default)
1826@item endall
1827end both streams
1828@item pass
1829pass through the main input
1830@end table
1831
58935b25
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1832@end table
1833
1834Be aware that frames are taken from each input video in timestamp
1835order, hence, if their initial timestamps differ, it is a a good idea
1836to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1837have them begin in the same zero timestamp, as it does the example for
1838the @var{movie} filter.
1839
1840Follow some examples:
1841@example
1842# draw the overlay at 10 pixels from the bottom right
1843# corner of the main video.
9087eaf1 1844overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
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1845
1846# insert a transparent PNG logo in the bottom left corner of the input
9087eaf1 1847avconv -i input -i logo -filter_complex 'overlay=x=10:y=main_h-overlay_h-10' output
58935b25
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1848
1849# insert 2 different transparent PNG logos (second logo on bottom
1850# right corner):
7ce118ba 1851avconv -i input -i logo1 -i logo2 -filter_complex
9087eaf1 1852'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
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1853
1854# add a transparent color layer on top of the main video,
1855# WxH specifies the size of the main input to the overlay filter
1856color=red@.3:WxH [over]; [in][over] overlay [out]
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1857
1858# mask 10-20 seconds of a video by applying the delogo filter to a section
1859avconv -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
1860-vf '[in]split[split_main][split_delogo];[split_delogo]trim=start=360:end=371,delogo=0:0:640:480[delogoed];[split_main][delogoed]overlay=eof_action=pass[out]'
1861masked.avi
58935b25
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1862@end example
1863
b0641ab7 1864You can chain together more overlays but the efficiency of such
58935b25
SS
1865approach is yet to be tested.
1866
3275ac6a
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1867@section pad
1868
1869Add paddings to the input image, and places the original input at the
1870given coordinates @var{x}, @var{y}.
1871
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1872This filter accepts the following parameters:
1873
1874@table @option
1875@item width, height
1876
1877Specify the size of the output image with the paddings added. If the
1878value for @var{width} or @var{height} is 0, the corresponding input size
1879is used for the output.
1880
1881The @var{width} expression can reference the value set by the
1882@var{height} expression, and vice versa.
1883
1884The default value of @var{width} and @var{height} is 0.
1885
1886@item x, y
1887
1888Specify the offsets where to place the input image in the padded area
1889with respect to the top/left border of the output image.
1890
1891The @var{x} expression can reference the value set by the @var{y}
1892expression, and vice versa.
1893
1894The default value of @var{x} and @var{y} is 0.
1895
1896@item color
1897
1898Specify the color of the padded area, it can be the name of a color
1899(case insensitive match) or a 0xRRGGBB[AA] sequence.
1900
1901The default value of @var{color} is "black".
1902
1903@end table
3275ac6a 1904
73a4f7c2
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1905The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1906expressions containing the following constants:
1907
1908@table @option
1909@item E, PI, PHI
1910the corresponding mathematical approximated values for e
1911(euler number), pi (greek PI), phi (golden ratio)
1912
1913@item in_w, in_h
e83c2dde 1914the input video width and height
73a4f7c2
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1915
1916@item iw, ih
1917same as @var{in_w} and @var{in_h}
1918
1919@item out_w, out_h
e83c2dde 1920the output width and height, that is the size of the padded area as
73a4f7c2
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1921specified by the @var{width} and @var{height} expressions
1922
1923@item ow, oh
1924same as @var{out_w} and @var{out_h}
1925
1926@item x, y
1927x and y offsets as specified by the @var{x} and @var{y}
1928expressions, or NAN if not yet specified
1929
1930@item a
1931input display aspect ratio, same as @var{iw} / @var{ih}
1932
1933@item hsub, vsub
1934horizontal and vertical chroma subsample values. For example for the
1935pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1936@end table
1937
73a4f7c2 1938Some examples follow:
3d17f4b9
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1939
1940@example
1941# Add paddings with color "violet" to the input video. Output video
1942# size is 640x480, the top-left corner of the input video is placed at
aeefbf61 1943# column 0, row 40.
40c885c5 1944pad=width=640:height=480:x=0:y=40:color=violet
73a4f7c2
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1945
1946# pad the input to get an output with dimensions increased bt 3/2,
1947# and put the input video at the center of the padded area
1948pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1949
1950# pad the input to get a squared output with size equal to the maximum
1951# value between the input width and height, and put the input video at
1952# the center of the padded area
1953pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1954
1955# pad the input to get a final w/h ratio of 16:9
1956pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1957
1958# double output size and put the input video in the bottom-right
1959# corner of the output padded area
1960pad="2*iw:2*ih:ow-iw:oh-ih"
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1961@end example
1962
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1963@section pixdesctest
1964
1965Pixel format descriptor test filter, mainly useful for internal
1966testing. The output video should be equal to the input video.
1967
1968For example:
1969@example
1970format=monow, pixdesctest
1971@end example
1972
1973can be used to test the monowhite pixel format descriptor definition.
1974
dd249245 1975@anchor{scale}
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1976@section scale
1977
c334c113 1978Scale the input video and/or convert the image format.
3275ac6a 1979
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1980This filter accepts the following options:
1981
1982@table @option
1983
1984@item w
1985Output video width.
1986
1987@item h
1988Output video height.
1989
1990@end table
1991
1992The parameters @var{w} and @var{h} are expressions containing
68e23c08 1993the following constants:
3275ac6a 1994
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1995@table @option
1996@item E, PI, PHI
1997the corresponding mathematical approximated values for e
1998(euler number), pi (greek PI), phi (golden ratio)
1999
2000@item in_w, in_h
e83c2dde 2001the input width and height
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2002
2003@item iw, ih
2004same as @var{in_w} and @var{in_h}
2005
2006@item out_w, out_h
e83c2dde 2007the output (cropped) width and height
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2008
2009@item ow, oh
2010same as @var{out_w} and @var{out_h}
3275ac6a 2011
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2012@item a
2013same as @var{iw} / @var{ih}
68e23c08 2014
46b29397
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2015@item sar
2016input sample aspect ratio
2017
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2018@item dar
2019input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2020
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2021@item hsub, vsub
2022horizontal and vertical chroma subsample values. For example for the
2023pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2024@end table
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2025
2026If the input image format is different from the format requested by
2027the next filter, the scale filter will convert the input to the
2028requested format.
2029
c334c113 2030If the value for @var{w} or @var{h} is 0, the respective input
3275ac6a
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2031size is used for the output.
2032
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2033If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
2034respective output size, a value that maintains the aspect ratio of the input
2035image.
3275ac6a 2036
c334c113 2037The default value of @var{w} and @var{h} is 0.
3275ac6a 2038
68e23c08
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2039Some examples follow:
2040@example
2041# scale the input video to a size of 200x100.
c334c113 2042scale=w=200:h=100
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2043
2044# scale the input to 2x
c334c113 2045scale=w=2*iw:h=2*ih
68e23c08
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2046# the above is the same as
2047scale=2*in_w:2*in_h
2048
2049# scale the input to half size
c334c113 2050scale=w=iw/2:h=ih/2
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2051
2052# increase the width, and set the height to the same size
2053scale=3/2*iw:ow
2054
2055# seek for Greek harmony
2056scale=iw:1/PHI*iw
2057scale=ih*PHI:ih
2058
2059# increase the height, and set the width to 3/2 of the height
c334c113 2060scale=w=3/2*oh:h=3/5*ih
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SS
2061
2062# increase the size, but make the size a multiple of the chroma
2063scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
2064
2065# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
c334c113 2066scale=w='min(500\, iw*3/2):h=-1'
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2067@end example
2068
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2069@section select
2070Select frames to pass in output.
2071
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2072This filter accepts the following options:
2073
2074@table @option
2075
2076@item expr
2077An expression, which is evaluated for each input frame. If the expression is
2078evaluated to a non-zero value, the frame is selected and passed to the output,
2079otherwise it is discarded.
2080
2081@end table
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2082
2083The expression can contain the following constants:
2084
2085@table @option
2086@item PI
2087Greek PI
2088
2089@item PHI
2090golden ratio
2091
2092@item E
2093Euler number
2094
2095@item n
2096the sequential number of the filtered frame, starting from 0
2097
2098@item selected_n
2099the sequential number of the selected frame, starting from 0
2100
2101@item prev_selected_n
2102the sequential number of the last selected frame, NAN if undefined
2103
2104@item TB
2105timebase of the input timestamps
2106
2107@item pts
2108the PTS (Presentation TimeStamp) of the filtered video frame,
2109expressed in @var{TB} units, NAN if undefined
2110
2111@item t
2112the PTS (Presentation TimeStamp) of the filtered video frame,
2113expressed in seconds, NAN if undefined
2114
2115@item prev_pts
2116the PTS of the previously filtered video frame, NAN if undefined
2117
2118@item prev_selected_pts
2119the PTS of the last previously filtered video frame, NAN if undefined
2120
2121@item prev_selected_t
2122the PTS of the last previously selected video frame, NAN if undefined
2123
2124@item start_pts
2125the PTS of the first video frame in the video, NAN if undefined
2126
2127@item start_t
2128the time of the first video frame in the video, NAN if undefined
2129
2130@item pict_type
2131the type of the filtered frame, can assume one of the following
2132values:
2133@table @option
2134@item I
2135@item P
2136@item B
2137@item S
2138@item SI
2139@item SP
2140@item BI
2141@end table
2142
2143@item interlace_type
2144the frame interlace type, can assume one of the following values:
2145@table @option
2146@item PROGRESSIVE
2147the frame is progressive (not interlaced)
2148@item TOPFIRST
2149the frame is top-field-first
2150@item BOTTOMFIRST
2151the frame is bottom-field-first
2152@end table
2153
2154@item key
21551 if the filtered frame is a key-frame, 0 otherwise
2156
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2157@end table
2158
2159The default value of the select expression is "1".
2160
2161Some examples follow:
2162
2163@example
2164# select all frames in input
2165select
2166
2167# the above is the same as:
95f1f56a 2168select=expr=1
d763fb7d
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2169
2170# skip all frames:
95f1f56a 2171select=expr=0
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2172
2173# select only I-frames
95f1f56a 2174select='expr=eq(pict_type\,I)'
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2175
2176# select one frame every 100
2177select='not(mod(n\,100))'
2178
2179# select only frames contained in the 10-20 time interval
2180select='gte(t\,10)*lte(t\,20)'
2181
2182# select only I frames contained in the 10-20 time interval
2183select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2184
2185# select frames with a minimum distance of 10 seconds
2186select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2187@end example
2188
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2189@anchor{setdar}
2190@section setdar
2191
2192Set the Display Aspect Ratio for the filter output video.
2193
2194This is done by changing the specified Sample (aka Pixel) Aspect
2195Ratio, according to the following equation:
2196@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2197
2198Keep in mind that this filter does not modify the pixel dimensions of
2199the video frame. Also the display aspect ratio set by this filter may
2200be changed by later filters in the filterchain, e.g. in case of
2201scaling or if another "setdar" or a "setsar" filter is applied.
2202
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2203This filter accepts the following options:
2204
2205@table @option
2206
2207@item dar
34a0ac41 2208Output display aspect ratio.
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2209
2210@end table
2fd8756b 2211
34a0ac41
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2212The parameter @var{dar} is an expression containing
2213the following constants:
2214
2215@table @option
2216@item E, PI, PHI
2217the corresponding mathematical approximated values for e
2218(euler number), pi (greek PI), phi (golden ratio)
2219
2220@item w, h
2221the input width and height
2222
2223@item a
2224same as @var{w} / @var{h}
2225
2226@item sar
2227input sample aspect ratio
2228
2229@item dar
2230input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2231
2232@item hsub, vsub
2233horizontal and vertical chroma subsample values. For example for the
2234pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2235@end table
2236
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2237For example to change the display aspect ratio to 16:9, specify:
2238@example
2831b307 2239setdar=dar=16/9
2fd8756b 2240# the above is equivalent to
2831b307 2241setdar=dar=1.77777
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2242@end example
2243
4c989761 2244See also the @ref{setsar} filter documentation.
2fd8756b 2245
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2246@section setpts
2247
2248Change the PTS (presentation timestamp) of the input video frames.
2249
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2250This filter accepts the following options:
2251
2252@table @option
2253
2254@item expr
2255The expression which is evaluated for each frame to construct its timestamp.
2256
2257@end table
2258
2259The expression is evaluated through the eval API and can contain the following
2260constants:
a532bb39
SS
2261
2262@table @option
2263@item PTS
2264the presentation timestamp in input
2265
2266@item PI
2267Greek PI
2268
2269@item PHI
2270golden ratio
2271
2272@item E
2273Euler number
2274
2275@item N
2276the count of the input frame, starting from 0.
2277
2278@item STARTPTS
2279the PTS of the first video frame
2280
2281@item INTERLACED
2282tell if the current frame is interlaced
2283
a532bb39
SS
2284@item PREV_INPTS
2285previous input PTS
2286
2287@item PREV_OUTPTS
2288previous output PTS
2289
0b55b16a
VP
2290@item RTCTIME
2291wallclock (RTC) time in microseconds
2292
2293@item RTCSTART
2294wallclock (RTC) time at the start of the movie in microseconds
2295
0ebfdae0
CW
2296@item TB
2297timebase of the input timestamps
2298
a532bb39
SS
2299@end table
2300
2301Some examples follow:
2302
2303@example
2304# start counting PTS from zero
33b97faa 2305setpts=expr=PTS-STARTPTS
a532bb39
SS
2306
2307# fast motion
33b97faa 2308setpts=expr=0.5*PTS
a532bb39
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2309
2310# slow motion
2311setpts=2.0*PTS
2312
2313# fixed rate 25 fps
2314setpts=N/(25*TB)
2315
2316# fixed rate 25 fps with some jitter
2317setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
0b55b16a
VP
2318
2319# generate timestamps from a "live source" and rebase onto the current timebase
2320setpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
a532bb39
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2321@end example
2322
2fd8756b
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2323@anchor{setsar}
2324@section setsar
2325
2326Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
2327
2328Note that as a consequence of the application of this filter, the
2329output display aspect ratio will change according to the following
2330equation:
2331@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2332
2333Keep in mind that the sample aspect ratio set by this filter may be
2334changed by later filters in the filterchain, e.g. if another "setsar"
2335or a "setdar" filter is applied.
2336
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2337This filter accepts the following options:
2338
2339@table @option
2340
2341@item sar
34a0ac41 2342Output sample aspect ratio.
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2343
2344@end table
2fd8756b 2345
34a0ac41
RP
2346The parameter @var{sar} is an expression containing
2347the following constants:
2348
2349@table @option
2350@item E, PI, PHI
2351the corresponding mathematical approximated values for e
2352(euler number), pi (greek PI), phi (golden ratio)
2353
2354@item w, h
2355the input width and height
2356
2357@item a
2358same as @var{w} / @var{h}
2359
2360@item sar
2361input sample aspect ratio
2362
2363@item dar
2364input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2365
2366@item hsub, vsub
2367horizontal and vertical chroma subsample values. For example for the
2368pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2369@end table
2370
2fd8756b
SS
2371For example to change the sample aspect ratio to 10:11, specify:
2372@example
2831b307 2373setsar=sar=10/11
2fd8756b
SS
2374@end example
2375
d89e3b36
SS
2376@section settb
2377
2378Set the timebase to use for the output frames timestamps.
2379It is mainly useful for testing timebase configuration.
2380
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2381This filter accepts the following options:
2382
2383@table @option
2384
2385@item expr
2386The expression which is evaluated into the output timebase.
2387
2388@end table
2389
d89e3b36
SS
2390The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
2391default timebase), and "intb" (the input timebase).
2392
2393The default value for the input is "intb".
2394
2395Follow some examples.
2396
2397@example
2398# set the timebase to 1/25
ffea3b00 2399settb=expr=1/25
d89e3b36
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2400
2401# set the timebase to 1/10
ffea3b00 2402settb=expr=0.1
d89e3b36
SS
2403
2404#set the timebase to 1001/1000
2405settb=1+0.001
2406
2407#set the timebase to 2*intb
2408settb=2*intb
2409
2410#set the default timebase value
2411settb=AVTB
2412@end example
2413
ee42716b
SS
2414@section showinfo
2415
2416Show a line containing various information for each input video frame.
2417The input video is not modified.
2418
2419The shown line contains a sequence of key/value pairs of the form
2420@var{key}:@var{value}.
2421
2422A description of each shown parameter follows:
2423
2424@table @option
2425@item n
2426sequential number of the input frame, starting from 0
2427
2428@item pts
2429Presentation TimeStamp of the input frame, expressed as a number of
2430time base units. The time base unit depends on the filter input pad.
2431
2432@item pts_time
2433Presentation TimeStamp of the input frame, expressed as a number of
2434seconds
2435
2436@item pos
2437position of the frame in the input stream, -1 if this information in
da9cea77 2438unavailable and/or meaningless (for example in case of synthetic video)
ee42716b
SS
2439
2440@item fmt
2441pixel format name
2442
2443@item sar
2444sample aspect ratio of the input frame, expressed in the form
2445@var{num}/@var{den}
2446
2447@item s
2448size of the input frame, expressed in the form
2449@var{width}x@var{height}
2450
2451@item i
2452interlaced mode ("P" for "progressive", "T" for top field first, "B"
2453for bottom field first)
2454
2455@item iskey
24561 if the frame is a key frame, 0 otherwise
2457
2458@item type
2459picture type of the input frame ("I" for an I-frame, "P" for a
2460P-frame, "B" for a B-frame, "?" for unknown type).
2461Check also the documentation of the @code{AVPictureType} enum and of
2462the @code{av_get_picture_type_char} function defined in
2463@file{libavutil/avutil.h}.
2464
2465@item checksum
2466Adler-32 checksum of all the planes of the input frame
2467
2468@item plane_checksum
2469Adler-32 checksum of each plane of the input frame, expressed in the form
2470"[@var{c0} @var{c1} @var{c2} @var{c3}]"
2471@end table
2472
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2473@section shuffleplanes
2474
2475Reorder and/or duplicate video planes.
2476
2477This filter accepts the following options:
2478
2479@table @option
2480
2481@item map0
2482The index of the input plane to be used as the first output plane.
2483
2484@item map1
2485The index of the input plane to be used as the second output plane.
2486
2487@item map2
2488The index of the input plane to be used as the third output plane.
2489
2490@item map3
2491The index of the input plane to be used as the fourth output plane.
2492
2493@end table
2494
2495The first plane has the index 0. The default is to keep the input unchanged.
2496
2497E.g.
2498@example
2499avconv -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
2500@end example
2501swaps the second and third planes of the input.
2502
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2503@section split
2504
2505Split input video into several identical outputs.
2506
2507The filter accepts a single parameter which specifies the number of outputs. If
2508unspecified, it defaults to 2.
2509
2510For example
2511@example
2512avconv -i INPUT -filter_complex split=5 OUTPUT
2513@end example
2514will create 5 copies of the input video.
2515
43945b27
SS
2516@section transpose
2517
2518Transpose rows with columns in the input video and optionally flip it.
2519
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2520This filter accepts the following options:
2521
2522@table @option
2523
2524@item dir
2525The direction of the transpose.
2526
2527@end table
2528
2529The direction can assume the following values:
43945b27
SS
2530
2531@table @samp
0c2466de 2532@item cclock_flip
43945b27
SS
2533Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2534@example
2535L.R L.l
2536. . -> . .
2537l.r R.r
2538@end example
2539
0c2466de 2540@item clock
43945b27
SS
2541Rotate by 90 degrees clockwise, that is:
2542@example
2543L.R l.L
2544. . -> . .
2545l.r r.R
2546@end example
2547
0c2466de 2548@item cclock
43945b27
SS
2549Rotate by 90 degrees counterclockwise, that is:
2550@example
2551L.R R.r
2552. . -> . .
2553l.r L.l
2554@end example
2555
0c2466de 2556@item clock_flip
43945b27
SS
2557Rotate by 90 degrees clockwise and vertically flip, that is:
2558@example
2559L.R r.R
2560. . -> . .
2561l.r l.L
2562@end example
2563@end table
2564
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2565@section trim
2566Trim the input so that the output contains one continuous subpart of the input.
2567
2568This filter accepts the following options:
2569@table @option
2570@item start
2571Timestamp (in seconds) of the start of the kept section. I.e. the frame with the
2572timestamp @var{start} will be the first frame in the output.
2573
2574@item end
2575Timestamp (in seconds) of the first frame that will be dropped. I.e. the frame
2576immediately preceding the one with the timestamp @var{end} will be the last
2577frame in the output.
2578
2579@item start_pts
2580Same as @var{start}, except this option sets the start timestamp in timebase
2581units instead of seconds.
2582
2583@item end_pts
2584Same as @var{end}, except this option sets the end timestamp in timebase units
2585instead of seconds.
2586
2587@item duration
2588Maximum duration of the output in seconds.
2589
2590@item start_frame
2591Number of the first frame that should be passed to output.
2592
2593@item end_frame
2594Number of the first frame that should be dropped.
2595@end table
2596
2597Note that the first two sets of the start/end options and the @option{duration}
2598option look at the frame timestamp, while the _frame variants simply count the
2599frames that pass through the filter. Also note that this filter does not modify
2600the timestamps. If you wish that the output timestamps start at zero, insert a
2601setpts filter after the trim filter.
2602
2603If multiple start or end options are set, this filter tries to be greedy and
2604keep all the frames that match at least one of the specified constraints. To keep
2605only the part that matches all the constraints at once, chain multiple trim
2606filters.
2607
2608The defaults are such that all the input is kept. So it is possible to set e.g.
2609just the end values to keep everything before the specified time.
2610
2611Examples:
2612@itemize
2613@item
2614drop everything except the second minute of input
2615@example
2616avconv -i INPUT -vf trim=60:120
2617@end example
2618
2619@item
2620keep only the first second
2621@example
2622avconv -i INPUT -vf trim=duration=1
2623@end example
2624
2625@end itemize
3275ac6a
SS
2626@section unsharp
2627
843b5fd0
SS
2628Sharpen or blur the input video.
2629
2630It accepts the following parameters:
3275ac6a
SS
2631
2632@table @option
2633
2634@item luma_msize_x
2635Set the luma matrix horizontal size. It can be an integer between 3
2636and 13, default value is 5.
2637
2638@item luma_msize_y
2639Set the luma matrix vertical size. It can be an integer between 3
2640and 13, default value is 5.
2641
2642@item luma_amount
2643Set the luma effect strength. It can be a float number between -2.0
2644and 5.0, default value is 1.0.
2645
2646@item chroma_msize_x
2647Set the chroma matrix horizontal size. It can be an integer between 3
1ee20141 2648and 13, default value is 5.
3275ac6a
SS
2649
2650@item chroma_msize_y
2651Set the chroma matrix vertical size. It can be an integer between 3
1ee20141 2652and 13, default value is 5.
3275ac6a 2653
2725f2d4 2654@item chroma_amount
3275ac6a
SS
2655Set the chroma effect strength. It can be a float number between -2.0
2656and 5.0, default value is 0.0.
2657
2658@end table
2659
b83e9efc
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2660Negative values for the amount will blur the input video, while positive
2661values will sharpen. All parameters are optional and default to the
2662equivalent of the string '5:5:1.0:5:5:0.0'.
2663
3275ac6a
SS
2664@example
2665# Strong luma sharpen effect parameters
b83e9efc 2666unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
3275ac6a
SS
2667
2668# Strong blur of both luma and chroma parameters
2669unsharp=7:7:-2:7:7:-2
2670
9270b8a3
LB
2671# Use the default values with @command{avconv}
2672./avconv -i in.avi -vf "unsharp" out.mp4
3275ac6a
SS
2673@end example
2674
2675@section vflip
2676
2677Flip the input video vertically.
2678
2679@example
9270b8a3 2680./avconv -i in.avi -vf "vflip" out.avi
3275ac6a
SS
2681@end example
2682
acbac567
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2683@section yadif
2684
1653027a
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2685Deinterlace the input video ("yadif" means "yet another deinterlacing
2686filter").
acbac567 2687
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2688This filter accepts the following options:
2689
2690@table @option
acbac567 2691
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2692@item mode
2693The interlacing mode to adopt, accepts one of the following values:
acbac567 2694
1653027a
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2695@table @option
2696@item 0
2697output 1 frame for each frame
2698@item 1
2699output 1 frame for each field
2700@item 2
2701like 0 but skips spatial interlacing check
2702@item 3
2703like 1 but skips spatial interlacing check
2704@end table
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2705
2706Default value is 0.
2707
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2708@item parity
2709The picture field parity assumed for the input interlaced video, accepts one of
2710the following values:
acbac567 2711
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2712@table @option
2713@item 0
1653027a 2714assume top field first
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2715@item 1
2716assume bottom field first
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2717@item -1
2718enable automatic detection
acbac567
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2719@end table
2720
1653027a 2721Default value is -1.
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2722If interlacing is unknown or decoder does not export this information,
2723top field first will be assumed.
1653027a 2724
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2725@item auto
2726Whether deinterlacer should trust the interlaced flag and only deinterlace
2727frames marked as interlaced
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2728
2729@table @option
2730@item 0
2731deinterlace all frames
2732@item 1
2733only deinterlace frames marked as interlaced
2734@end table
2735
2736Default value is 0.
2737
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2738@end table
2739
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2740@c man end VIDEO FILTERS
2741
2742@chapter Video Sources
2743@c man begin VIDEO SOURCES
2744
2745Below is a description of the currently available video sources.
2746
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2747@section buffer
2748
2749Buffer video frames, and make them available to the filter chain.
2750
2751This source is mainly intended for a programmatic use, in particular
ac1a31ab 2752through the interface defined in @file{libavfilter/vsrc_buffer.h}.
24413399 2753
d28cb849 2754This filter accepts the following parameters:
24413399 2755
d28cb849 2756@table @option
24413399 2757
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2758@item width
2759Input video width.
24413399 2760
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2761@item height
2762Input video height.
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2764@item pix_fmt
2765Name of the input video pixel format.
24413399 2766
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2767@item time_base
2768The time base used for input timestamps.
24413399 2769
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2770@item sar
2771Sample (pixel) aspect ratio of the input video.
7a11c82f 2772
24413399
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2773@end table
2774
2775For example:
2776@example
d28cb849 2777buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
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2778@end example
2779
2780will instruct the source to accept video frames with size 320x240 and
7a11c82f
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2781with format "yuv410p", assuming 1/24 as the timestamps timebase and
2782square pixels (1:1 sample aspect ratio).
24413399 2783
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2784@section color
2785
2786Provide an uniformly colored input.
2787
2788It accepts the following parameters:
23ccf3c7
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2789
2790@table @option
2791
2792@item color
2793Specify the color of the source. It can be the name of a color (case
2794insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2795alpha specifier. The default value is "black".
2796
7bc1a883 2797@item size
23ccf3c7 2798Specify the size of the sourced video, it may be a string of the form
e83c2dde 2799@var{width}x@var{height}, or the name of a size abbreviation. The
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2800default value is "320x240".
2801
7bc1a883 2802@item framerate
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2803Specify the frame rate of the sourced video, as the number of frames
2804generated per second. It has to be a string in the format
2805@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2806number or a valid video frame rate abbreviation. The default value is
2807"25".
2808
2809@end table
2810
2811For example the following graph description will generate a red source
2812with an opacity of 0.2, with size "qcif" and a frame rate of 10
2813frames per second, which will be overlayed over the source connected
2814to the pad with identifier "in".
2815
2816@example
2817"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2818@end example
2819
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2820@section movie
2821
2822Read a video stream from a movie container.
2823
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2824Note that this source is a hack that bypasses the standard input path. It can be
2825useful in applications that do not support arbitrary filter graphs, but its use
2826is discouraged in those that do. Specifically in @command{avconv} this filter
2827should never be used, the @option{-filter_complex} option fully replaces it.
2828
a42d6e6c 2829This filter accepts the following options:
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2830
2831@table @option
2832
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2833@item filename
2834The name of the resource to read (not necessarily a file but also a device or a
2835stream accessed through some protocol).
2836
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2837@item format_name, f
2838Specifies the format assumed for the movie to read, and can be either
2839the name of a container or an input device. If not specified the
2840format is guessed from @var{movie_name} or by probing.
2841
2842@item seek_point, sp
2843Specifies the seek point in seconds, the frames will be output
2844starting from this seek point, the parameter is evaluated with
2845@code{av_strtod} so the numerical value may be suffixed by an IS
2846postfix. Default value is "0".
2847
2848@item stream_index, si
2849Specifies the index of the video stream to read. If the value is -1,
2850the best suited video stream will be automatically selected. Default
2851value is "-1".
2852
2853@end table
2854
2855This filter allows to overlay a second video on top of main input of
2856a filtergraph as shown in this graph:
2857@example
2858input -----------> deltapts0 --> overlay --> output
2859 ^
2860 |
2861movie --> scale--> deltapts1 -------+
2862@end example
2863
2864Some examples follow:
2865@example
2866# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
2867# on top of the input labelled as "in".
2868movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2869[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2870
2871# read from a video4linux2 device, and overlay it on top of the input
2872# labelled as "in"
2873movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2874[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2875
2876@end example
2877
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2878@section nullsrc
2879
2880Null video source, never return images. It is mainly useful as a
2881template and to be employed in analysis / debugging tools.
2882
2883It accepts as optional parameter a string of the form
16134b7c 2884@var{width}:@var{height}:@var{timebase}.
3275ac6a 2885
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2886@var{width} and @var{height} specify the size of the configured
2887source. The default values of @var{width} and @var{height} are
2888respectively 352 and 288 (corresponding to the CIF size format).
2889
2890@var{timebase} specifies an arithmetic expression representing a
2891timebase. The expression can contain the constants "PI", "E", "PHI",
2892"AVTB" (the default timebase), and defaults to the value "AVTB".
3275ac6a 2893
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2894@section frei0r_src
2895
2896Provide a frei0r source.
2897
2898To enable compilation of this filter you need to install the frei0r
f8a45fa1 2899header and configure Libav with --enable-frei0r.
f8608dca 2900
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2901This source accepts the following options:
2902
2903@table @option
2904
2905@item size
2906The size of the video to generate, may be a string of the form
2907@var{width}x@var{height} or a frame size abbreviation.
f8608dca 2908
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2909@item framerate
2910Framerate of the generated video, may be a string of the form
2911@var{num}/@var{den} or a frame rate abbreviation.
2912
2913@item filter_name
2914The name to the frei0r source to load. For more information regarding frei0r and
2915how to set the parameters read the section @ref{frei0r} in the description of
2916the video filters.
2917
2918@item filter_params
2919A '|'-separated list of parameters to pass to the frei0r source.
2920
2921@end table
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2922
2923Some examples follow:
2924@example
2925# generate a frei0r partik0l source with size 200x200 and framerate 10
2926# which is overlayed on the overlay filter main input
5aa1a668 2927frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
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2928@end example
2929
ec2ac927 2930@section rgbtestsrc, testsrc
0244879f 2931
ec2ac927
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2932The @code{rgbtestsrc} source generates an RGB test pattern useful for
2933detecting RGB vs BGR issues. You should see a red, green and blue
2934stripe from top to bottom.
0244879f 2935
ec2ac927
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2936The @code{testsrc} source generates a test video pattern, showing a
2937color pattern, a scrolling gradient and a timestamp. This is mainly
2938intended for testing purposes.
2939
7b3eb745 2940The sources accept the following options:
0244879f
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2941
2942@table @option
2943
2944@item size, s
2945Specify the size of the sourced video, it may be a string of the form
da9cea77 2946@var{width}x@var{height}, or the name of a size abbreviation. The
0244879f
SS
2947default value is "320x240".
2948
2949@item rate, r
2950Specify the frame rate of the sourced video, as the number of frames
2951generated per second. It has to be a string in the format
2952@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2953number or a valid video frame rate abbreviation. The default value is
2954"25".
2955
2956@item sar
2957Set the sample aspect ratio of the sourced video.
2958
2959@item duration
2960Set the video duration of the sourced video. The accepted syntax is:
2961@example
2962[-]HH[:MM[:SS[.m...]]]
2963[-]S+[.m...]
2964@end example
2965See also the function @code{av_parse_time()}.
2966
2967If not specified, or the expressed duration is negative, the video is
2968supposed to be generated forever.
2969@end table
2970
2971For example the following:
2972@example
2973testsrc=duration=5.3:size=qcif:rate=10
2974@end example
2975
2976will generate a video with a duration of 5.3 seconds, with size
2977176x144 and a framerate of 10 frames per second.
2978
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2979@c man end VIDEO SOURCES
2980
2981@chapter Video Sinks
2982@c man begin VIDEO SINKS
2983
2984Below is a description of the currently available video sinks.
2985
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2986@section buffersink
2987
2988Buffer video frames, and make them available to the end of the filter
2989graph.
2990
2991This sink is intended for a programmatic use through the interface defined in
2992@file{libavfilter/buffersink.h}.
2993
3275ac6a
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2994@section nullsink
2995
2996Null video sink, do absolutely nothing with the input video. It is
2997mainly useful as a template and to be employed in analysis / debugging
2998tools.
2999
3000@c man end VIDEO SINKS