af_volume: implement replaygain pre-amplification
[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
637@item replaygain_preamp
638Pre-amplification gain in dB to apply to the selected replaygain gain.
639
640Default value for @var{replaygain_preamp} is 0.0.
641
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642@end table
643
644@subsection Examples
645
646@itemize
647@item
648Halve the input audio volume:
649@example
650volume=volume=0.5
651volume=volume=1/2
652volume=volume=-6.0206dB
653@end example
654
655@item
656Increase input audio power by 6 decibels using fixed-point precision:
657@example
658volume=volume=6dB:precision=fixed
659@end example
660@end itemize
661
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662@c man end AUDIO FILTERS
663
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664@chapter Audio Sources
665@c man begin AUDIO SOURCES
666
667Below is a description of the currently available audio sources.
668
669@section anullsrc
670
671Null audio source, never return audio frames. It is mainly useful as a
672template and to be employed in analysis / debugging tools.
673
674It accepts as optional parameter a string of the form
675@var{sample_rate}:@var{channel_layout}.
676
677@var{sample_rate} specify the sample rate, and defaults to 44100.
678
679@var{channel_layout} specify the channel layout, and can be either an
680integer or a string representing a channel layout. The default value
681of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
682
683Check the channel_layout_map definition in
a903f8f0 684@file{libavutil/channel_layout.c} for the mapping between strings and
6ef93402 685channel layout values.
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686
687Follow some examples:
688@example
689# set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
690anullsrc=48000:4
691
692# same as
693anullsrc=48000:mono
694@end example
695
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696@section abuffer
697Buffer audio frames, and make them available to the filter chain.
698
699This source is not intended to be part of user-supplied graph descriptions but
700for insertion by calling programs through the interface defined in
701@file{libavfilter/buffersrc.h}.
702
703It accepts the following named parameters:
704@table @option
705
706@item time_base
707Timebase which will be used for timestamps of submitted frames. It must be
708either a floating-point number or in @var{numerator}/@var{denominator} form.
709
710@item sample_rate
711Audio sample rate.
712
713@item sample_fmt
714Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
715
716@item channel_layout
717Channel layout of the audio data, in the form that can be accepted by
718@code{av_get_channel_layout()}.
719@end table
720
721All the parameters need to be explicitly defined.
722
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723@c man end AUDIO SOURCES
724
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725@chapter Audio Sinks
726@c man begin AUDIO SINKS
727
728Below is a description of the currently available audio sinks.
729
730@section anullsink
731
732Null audio sink, do absolutely nothing with the input audio. It is
733mainly useful as a template and to be employed in analysis / debugging
734tools.
735
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736@section abuffersink
737This sink is intended for programmatic use. Frames that arrive on this sink can
738be retrieved by the calling program using the interface defined in
739@file{libavfilter/buffersink.h}.
740
741This filter accepts no parameters.
742
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743@c man end AUDIO SINKS
744
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745@chapter Video Filters
746@c man begin VIDEO FILTERS
747
f8a45fa1 748When you configure your Libav build, you can disable any of the
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749existing filters using --disable-filters.
750The configure output will show the video filters included in your
751build.
752
753Below is a description of the currently available video filters.
754
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755@section blackframe
756
757Detect frames that are (almost) completely black. Can be useful to
758detect chapter transitions or commercials. Output lines consist of
759the frame number of the detected frame, the percentage of blackness,
760the position in the file if known or -1 and the timestamp in seconds.
761
762In order to display the output lines, you need to set the loglevel at
763least to the AV_LOG_INFO value.
764
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765The filter accepts the following options:
766
767@table @option
768
769@item amount
770The percentage of the pixels that have to be below the threshold, defaults to
77198.
13fabd7a 772
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773@item threshold
774Threshold below which a pixel value is considered black, defaults to 32.
13fabd7a 775
62dcdb02 776@end table
13fabd7a 777
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778@section boxblur
779
780Apply boxblur algorithm to the input video.
781
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782This filter accepts the following options:
783
784@table @option
785
786@item luma_radius
787@item luma_power
788@item chroma_radius
789@item chroma_power
790@item alpha_radius
791@item alpha_power
792
793@end table
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794
795Chroma and alpha parameters are optional, if not specified they default
796to the corresponding values set for @var{luma_radius} and
797@var{luma_power}.
798
799@var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
800the radius in pixels of the box used for blurring the corresponding
801input plane. They are expressions, and can contain the following
802constants:
803@table @option
804@item w, h
da9cea77 805the input width and height in pixels
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806
807@item cw, ch
808the input chroma image width and height in pixels
809
810@item hsub, vsub
811horizontal and vertical chroma subsample values. For example for the
812pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
813@end table
814
815The radius must be a non-negative number, and must not be greater than
816the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
817and of @code{min(cw,ch)/2} for the chroma planes.
818
819@var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
820how many times the boxblur filter is applied to the corresponding
821plane.
822
823Some examples follow:
824
825@itemize
826
827@item
828Apply a boxblur filter with luma, chroma, and alpha radius
829set to 2:
830@example
51def31d 831boxblur=luma_radius=2:luma_power=1
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832@end example
833
834@item
835Set luma radius to 2, alpha and chroma radius to 0
836@example
837boxblur=2:1:0:0:0:0
838@end example
839
840@item
841Set luma and chroma radius to a fraction of the video dimension
842@example
51def31d 843boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
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844@end example
845
846@end itemize
847
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848@section copy
849
850Copy the input source unchanged to the output. Mainly useful for
851testing purposes.
852
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853@section crop
854
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855Crop the input video to given dimensions.
856
857This filter accepts the following options:
858
859@table @option
860
861@item out_w
862Width of the output video.
863
864@item out_h
865Height of the output video.
866
867@item x
868Horizontal position, in the input video, of the left edge of the output video.
869
870@item y
871Vertical position, in the input video, of the top edge of the output video.
872
873@end table
3275ac6a 874
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875The parameters are expressions containing the following constants:
876
877@table @option
878@item E, PI, PHI
879the corresponding mathematical approximated values for e
880(euler number), pi (greek PI), PHI (golden ratio)
881
882@item x, y
883the computed values for @var{x} and @var{y}. They are evaluated for
884each new frame.
885
886@item in_w, in_h
e83c2dde 887the input width and height
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888
889@item iw, ih
890same as @var{in_w} and @var{in_h}
891
892@item out_w, out_h
e83c2dde 893the output (cropped) width and height
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894
895@item ow, oh
896same as @var{out_w} and @var{out_h}
897
898@item n
899the number of input frame, starting from 0
900
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901@item t
902timestamp expressed in seconds, NAN if the input timestamp is unknown
3275ac6a 903
75b67a8a 904@end table
3275ac6a 905
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906The @var{out_w} and @var{out_h} parameters specify the expressions for
907the width and height of the output (cropped) video. They are
908evaluated just at the configuration of the filter.
3275ac6a 909
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910The default value of @var{out_w} is "in_w", and the default value of
911@var{out_h} is "in_h".
2bc05d35 912
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913The expression for @var{out_w} may depend on the value of @var{out_h},
914and the expression for @var{out_h} may depend on @var{out_w}, but they
915cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
916evaluated after @var{out_w} and @var{out_h}.
2bc05d35 917
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918The @var{x} and @var{y} parameters specify the expressions for the
919position of the top-left corner of the output (non-cropped) area. They
920are evaluated for each frame. If the evaluated value is not valid, it
921is approximated to the nearest valid value.
3275ac6a 922
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923The default value of @var{x} is "(in_w-out_w)/2", and the default
924value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
925the center of the input image.
926
927The expression for @var{x} may depend on @var{y}, and the expression
928for @var{y} may depend on @var{x}.
929
930Follow some examples:
3275ac6a 931@example
75b67a8a 932# crop the central input area with size 100x100
fba0156a 933crop=out_w=100:out_h=100
75b67a8a
SS
934
935# crop the central input area with size 2/3 of the input video
fba0156a 936"crop=out_w=2/3*in_w:out_h=2/3*in_h"
75b67a8a
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937
938# crop the input video central square
fba0156a 939crop=out_w=in_h
75b67a8a
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940
941# delimit the rectangle with the top-left corner placed at position
942# 100:100 and the right-bottom corner corresponding to the right-bottom
943# corner of the input image.
fba0156a 944crop=out_w=in_w-100:out_h=in_h-100:x=100:y=100
3275ac6a 945
e6dba1d8 946# crop 10 pixels from the left and right borders, and 20 pixels from
75b67a8a 947# the top and bottom borders
fba0156a 948"crop=out_w=in_w-2*10:out_h=in_h-2*20"
3275ac6a 949
75b67a8a 950# keep only the bottom right quarter of the input image
fba0156a 951"crop=out_w=in_w/2:out_h=in_h/2:x=in_w/2:y=in_h/2"
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952
953# crop height for getting Greek harmony
fba0156a 954"crop=out_w=in_w:out_h=1/PHI*in_w"
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955
956# trembling effect
957"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)"
958
e6dba1d8 959# erratic camera effect depending on timestamp
fba0156a 960"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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961
962# set x depending on the value of y
963"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
964@end example
3275ac6a 965
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966@section cropdetect
967
968Auto-detect crop size.
969
970Calculate necessary cropping parameters and prints the recommended
971parameters through the logging system. The detected dimensions
972correspond to the non-black area of the input video.
973
460e7b4f 974This filter accepts the following options:
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975
976@table @option
977
978@item limit
979Threshold, which can be optionally specified from nothing (0) to
980everything (255), defaults to 24.
981
982@item round
983Value which the width/height should be divisible by, defaults to
98416. The offset is automatically adjusted to center the video. Use 2 to
985get only even dimensions (needed for 4:2:2 video). 16 is best when
986encoding to most video codecs.
987
988@item reset
989Counter that determines after how many frames cropdetect will reset
990the previously detected largest video area and start over to detect
991the current optimal crop area. Defaults to 0.
992
993This can be useful when channel logos distort the video area. 0
994indicates never reset and return the largest area encountered during
995playback.
996@end table
997
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998@section delogo
999
1000Suppress a TV station logo by a simple interpolation of the surrounding
1001pixels. Just set a rectangle covering the logo and watch it disappear
1002(and sometimes something even uglier appear - your mileage may vary).
1003
63e58c55 1004This filter accepts the following options:
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1005@table @option
1006
1007@item x, y
1008Specify the top left corner coordinates of the logo. They must be
1009specified.
1010
1011@item w, h
1012Specify the width and height of the logo to clear. They must be
1013specified.
1014
1015@item band, t
1016Specify the thickness of the fuzzy edge of the rectangle (added to
1017@var{w} and @var{h}). The default value is 4.
1018
1019@item show
1020When set to 1, a green rectangle is drawn on the screen to simplify
1021finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
1022@var{band} is set to 4. The default value is 0.
1023
1024@end table
1025
1026Some examples follow.
1027
1028@itemize
1029
1030@item
1031Set a rectangle covering the area with top left corner coordinates 0,0
1032and size 100x77, setting a band of size 10:
1033@example
b157be1f
SS
1034delogo=x=0:y=0:w=100:h=77:band=10
1035@end example
1036
1037@end itemize
1038
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1039@section drawbox
1040
1041Draw a colored box on the input image.
1042
335c3129 1043This filter accepts the following options:
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SS
1044
1045@table @option
1046
1047@item x, y
1048Specify the top left corner coordinates of the box. Default to 0.
1049
1050@item width, height
1051Specify the width and height of the box, if 0 they are interpreted as
1052the input width and height. Default to 0.
1053
1054@item color
1055Specify the color of the box to write, it can be the name of a color
1056(case insensitive match) or a 0xRRGGBB[AA] sequence.
1057@end table
1058
1059Follow some examples:
1060@example
1061# draw a black box around the edge of the input image
1062drawbox
1063
1064# draw a box with color red and an opacity of 50%
335c3129 1065drawbox=x=10:y=20:width=200:height=60:color=red@@0.5"
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SS
1066@end example
1067
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1068@section drawtext
1069
1070Draw text string or text from specified file on top of video using the
1071libfreetype library.
1072
0c50edb7 1073To enable compilation of this filter you need to configure Libav with
a5b64584
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1074@code{--enable-libfreetype}.
1075
1076The filter also recognizes strftime() sequences in the provided text
1077and expands them accordingly. Check the documentation of strftime().
1078
a5b64584
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1079The description of the accepted parameters follows.
1080
1081@table @option
1082
1083@item fontfile
1084The font file to be used for drawing text. Path must be included.
1085This parameter is mandatory.
1086
1087@item text
1088The text string to be drawn. The text must be a sequence of UTF-8
1089encoded characters.
1090This parameter is mandatory if no file is specified with the parameter
1091@var{textfile}.
1092
1093@item textfile
1094A text file containing text to be drawn. The text must be a sequence
1095of UTF-8 encoded characters.
1096
1097This parameter is mandatory if no text string is specified with the
1098parameter @var{text}.
1099
1100If both text and textfile are specified, an error is thrown.
1101
1102@item x, y
1103The offsets where text will be drawn within the video frame.
1104Relative to the top/left border of the output image.
2cf74eca
LB
1105They accept expressions similar to the @ref{overlay} filter:
1106@table @option
1107
1108@item x, y
1109the computed values for @var{x} and @var{y}. They are evaluated for
1110each new frame.
1111
1112@item main_w, main_h
1113main input width and height
1114
1115@item W, H
1116same as @var{main_w} and @var{main_h}
1117
1118@item text_w, text_h
1119rendered text width and height
1120
1121@item w, h
1122same as @var{text_w} and @var{text_h}
1123
1124@item n
1125the number of frames processed, starting from 0
1126
1127@item t
1128timestamp expressed in seconds, NAN if the input timestamp is unknown
1129
1130@end table
a5b64584
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1131
1132The default value of @var{x} and @var{y} is 0.
1133
1134@item fontsize
1135The font size to be used for drawing text.
1136The default value of @var{fontsize} is 16.
1137
1138@item fontcolor
1139The color to be used for drawing fonts.
1140Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1141(e.g. "0xff000033"), possibly followed by an alpha specifier.
1142The default value of @var{fontcolor} is "black".
1143
1144@item boxcolor
1145The color to be used for drawing box around text.
1146Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1147(e.g. "0xff00ff"), possibly followed by an alpha specifier.
1148The default value of @var{boxcolor} is "white".
1149
1150@item box
1151Used to draw a box around text using background color.
1152Value should be either 1 (enable) or 0 (disable).
1153The default value of @var{box} is 0.
1154
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SS
1155@item shadowx, shadowy
1156The x and y offsets for the text shadow position with respect to the
1157position of the text. They can be either positive or negative
1158values. Default value for both is "0".
1159
1160@item shadowcolor
1161The color to be used for drawing a shadow behind the drawn text. It
1162can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1163form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1164The default value of @var{shadowcolor} is "black".
1165
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1166@item ft_load_flags
1167Flags to be used for loading the fonts.
1168
1169The flags map the corresponding flags supported by libfreetype, and are
1170a combination of the following values:
1171@table @var
1172@item default
1173@item no_scale
1174@item no_hinting
1175@item render
1176@item no_bitmap
1177@item vertical_layout
1178@item force_autohint
1179@item crop_bitmap
1180@item pedantic
1181@item ignore_global_advance_width
1182@item no_recurse
1183@item ignore_transform
1184@item monochrome
1185@item linear_design
1186@item no_autohint
1187@item end table
1188@end table
1189
1190Default value is "render".
1191
1192For more information consult the documentation for the FT_LOAD_*
1193libfreetype flags.
1194
1195@item tabsize
1196The size in number of spaces to use for rendering the tab.
1197Default value is 4.
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AU
1198
1199@item fix_bounds
1200If true, check and fix text coords to avoid clipping.
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1201@end table
1202
1203For example the command:
1204@example
1205drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1206@end example
1207
1208will draw "Test Text" with font FreeSerif, using the default values
1209for the optional parameters.
1210
1211The command:
1212@example
1213drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1214 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1215@end example
1216
1217will draw 'Test Text' with font FreeSerif of size 24 at position x=100
1218and y=50 (counting from the top-left corner of the screen), text is
1219yellow with a red box around it. Both the text and the box have an
1220opacity of 20%.
1221
1222Note that the double quotes are not necessary if spaces are not used
1223within the parameter list.
1224
1225For more information about libfreetype, check:
1226@url{http://www.freetype.org/}.
1227
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1228@section fade
1229
1230Apply fade-in/out effect to input video.
1231
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1232This filter accepts the following options:
1233
1234@table @option
aadfc9ee 1235
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1236@item type
1237The effect type -- can be either "in" for fade-in, or "out" for a fade-out
1238effect.
aadfc9ee 1239
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1240@item start_frame
1241The number of the start frame for starting to apply the fade effect.
aadfc9ee 1242
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1243@item nb_frames
1244The number of frames for which the fade effect has to last. At the end of the
1245fade-in effect the output video will have the same intensity as the input video,
1246at the end of the fade-out transition the output video will be completely black.
1247
1248@end table
aadfc9ee
BM
1249
1250A few usage examples follow, usable too as test scenarios.
1251@example
1252# fade in first 30 frames of video
b9dfee9f 1253fade=type=in:nb_frames=30
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1254
1255# fade out last 45 frames of a 200-frame video
b9dfee9f 1256fade=type=out:start_frame=155:nb_frames=45
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1257
1258# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
b9dfee9f 1259fade=type=in:start_frame=0:nb_frames=25, fade=type=out:start_frame=975:nb_frames=25
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1260
1261# make first 5 frames black, then fade in from frame 5-24
b9dfee9f 1262fade=type=in:start_frame=5:nb_frames=20
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BM
1263@end example
1264
2f84bb42
MH
1265@section fieldorder
1266
1267Transform the field order of the input video.
1268
a39c1540 1269This filter accepts the following options:
2f84bb42
MH
1270
1271@table @option
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AK
1272
1273@item order
1274Output field order. Valid values are @var{tff} for top field first or @var{bff}
1275for bottom field first.
2f84bb42
MH
1276@end table
1277
1278Default value is "tff".
1279
1280Transformation is achieved by shifting the picture content up or down
1281by one line, and filling the remaining line with appropriate picture content.
1282This method is consistent with most broadcast field order converters.
1283
1284If the input video is not flagged as being interlaced, or it is already
1285flagged as being of the required output field order then this filter does
1286not alter the incoming video.
1287
1288This filter is very useful when converting to or from PAL DV material,
1289which is bottom field first.
1290
1291For example:
1292@example
a39c1540 1293./avconv -i in.vob -vf "fieldorder=order=bff" out.dv
2f84bb42
MH
1294@end example
1295
7f1af825
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1296@section fifo
1297
1298Buffer input images and send them when they are requested.
1299
1300This filter is mainly useful when auto-inserted by the libavfilter
1301framework.
1302
1303The filter does not take parameters.
1304
3275ac6a
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1305@section format
1306
1307Convert the input video to one of the specified pixel formats.
1308Libavfilter will try to pick one that is supported for the input to
1309the next filter.
1310
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1311This filter accepts the following parameters:
1312@table @option
1313
1314@item pix_fmts
1315A '|'-separated list of pixel format names, for example
1316"pix_fmts=yuv420p|monow|rgb24".
1317
1318@end table
3275ac6a 1319
f150e4dc 1320Some examples follow:
3275ac6a 1321@example
f150e4dc 1322# convert the input video to the format "yuv420p"
e67a87ea 1323format=pix_fmts=yuv420p
3275ac6a 1324
f150e4dc 1325# convert the input video to any of the formats in the list
e67a87ea 1326format=pix_fmts=yuv420p|yuv444p|yuv410p
f150e4dc 1327@end example
3275ac6a 1328
dd249245 1329@anchor{fps}
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1330@section fps
1331
1332Convert the video to specified constant framerate by duplicating or dropping
1333frames as necessary.
1334
1335This filter accepts the following named parameters:
1336@table @option
1337
1338@item fps
1339Desired output framerate.
1340
545a0b80
JR
1341@item start_time
1342Assume the first PTS should be the given value, in seconds. This allows for
1343padding/trimming at the start of stream. By default, no assumption is made
1344about the first frame's expected PTS, so no padding or trimming is done.
1345For example, this could be set to 0 to pad the beginning with duplicates of
1346the first frame if a video stream starts after the audio stream or to trim any
1347frames with a negative PTS.
1348
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1349@end table
1350
a7d0e7ea
VG
1351@section framepack
1352
1353Pack two different video streams into a stereoscopic video, setting proper
1354metadata on supported codecs. The two views should have the same size and
1355framerate and processing will stop when the shorter video ends. Please note
1356that you may conveniently adjust view properties with the @ref{scale} and
1357@ref{fps} filters.
1358
1359This filter accepts the following named parameters:
1360@table @option
1361
1362@item format
1363Desired packing format. Supported values are:
1364
1365@table @option
1366
1367@item sbs
1368Views are next to each other (default).
1369
1370@item tab
1371Views are on top of each other.
1372
1373@item lines
1374Views are packed by line.
1375
1376@item columns
1377Views are eacked by column.
1378
1379@item frameseq
1380Views are temporally interleaved.
1381
1382@end table
1383
1384@end table
1385
1386Some examples follow:
1387
1388@example
1389# Convert left and right views into a frame sequential video.
1390avconv -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
1391
1392# Convert views into a side-by-side video with the same output resolution as the input.
1393avconv -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
1394@end example
1395
f8608dca 1396@anchor{frei0r}
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1397@section frei0r
1398
1399Apply a frei0r effect to the input video.
1400
1401To enable compilation of this filter you need to install the frei0r
f8a45fa1 1402header and configure Libav with --enable-frei0r.
47941088 1403
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1404This filter accepts the following options:
1405
1406@table @option
1407
1408@item filter_name
1409The name to the frei0r effect to load. If the environment variable
1410@env{FREI0R_PATH} is defined, the frei0r effect is searched in each one of the
1411directories specified by the colon separated list in @env{FREIOR_PATH},
1412otherwise in the standard frei0r paths, which are in this order:
1413@file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/},
1414@file{/usr/lib/frei0r-1/}.
47941088 1415
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1416@item filter_params
1417A '|'-separated list of parameters to pass to the frei0r effect.
47941088 1418
5aa1a668 1419@end table
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1420
1421A frei0r effect parameter can be a boolean (whose values are specified
1422with "y" and "n"), a double, a color (specified by the syntax
1423@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1424numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1425description), a position (specified by the syntax @var{X}/@var{Y},
1426@var{X} and @var{Y} being float numbers) and a string.
1427
1428The number and kind of parameters depend on the loaded effect. If an
1429effect parameter is not specified the default value is set.
1430
1431Some examples follow:
1432@example
1433# apply the distort0r effect, set the first two double parameters
5aa1a668 1434frei0r=filter_name=distort0r:filter_params=0.5|0.01
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1435
1436# apply the colordistance effect, takes a color as first parameter
1437frei0r=colordistance:0.2/0.3/0.4
1438frei0r=colordistance:violet
1439frei0r=colordistance:0x112233
1440
1441# apply the perspective effect, specify the top left and top right
1442# image positions
5aa1a668 1443frei0r=perspective:0.2/0.2|0.8/0.2
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1444@end example
1445
1446For more information see:
1447@url{http://piksel.org/frei0r}
1448
d5f187fd
N
1449@section gradfun
1450
1451Fix the banding artifacts that are sometimes introduced into nearly flat
1452regions by truncation to 8bit colordepth.
1453Interpolate the gradients that should go where the bands are, and
1454dither them.
1455
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1456This filter is designed for playback only. Do not use it prior to
1457lossy compression, because compression tends to lose the dither and
1458bring back the bands.
1459
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1460This filter accepts the following options:
1461
1462@table @option
d5f187fd 1463
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1464@item strength
1465The maximum amount by which the filter will change any one pixel. Also the
1466threshold for detecting nearly flat regions. Acceptable values range from .51 to
146764, default value is 1.2, out-of-range values will be clipped to the valid
1468range.
d5f187fd 1469
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1470@item radius
1471The neighborhood to fit the gradient to. A larger radius makes for smoother
1472gradients, but also prevents the filter from modifying the pixels near detailed
1473regions. Acceptable values are 8-32, default value is 16, out-of-range values
1474will be clipped to the valid range.
1475
1476@end table
d5f187fd
N
1477
1478@example
1479# default parameters
7ed833d7 1480gradfun=strength=1.2:radius=16
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N
1481
1482# omitting radius
1483gradfun=1.2
1484@end example
1485
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1486@section hflip
1487
1488Flip the input video horizontally.
1489
9270b8a3 1490For example to horizontally flip the input video with @command{avconv}:
a1e171df 1491@example
9270b8a3 1492avconv -i in.avi -vf "hflip" out.avi
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1493@end example
1494
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1495@section hqdn3d
1496
1497High precision/quality 3d denoise filter. This filter aims to reduce
1498image noise producing smooth images and making still images really
1499still. It should enhance compressibility.
1500
1501It accepts the following optional parameters:
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1502
1503@table @option
1504@item luma_spatial
1505a non-negative float number which specifies spatial luma strength,
1506defaults to 4.0
1507
1508@item chroma_spatial
1509a non-negative float number which specifies spatial chroma strength,
1510defaults to 3.0*@var{luma_spatial}/4.0
1511
1512@item luma_tmp
1513a float number which specifies luma temporal strength, defaults to
15146.0*@var{luma_spatial}/4.0
1515
1516@item chroma_tmp
1517a float number which specifies chroma temporal strength, defaults to
1518@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1519@end table
1520
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1521@section interlace
1522
1523Simple interlacing filter from progressive contents. This interleaves upper (or
1524lower) lines from odd frames with lower (or upper) lines from even frames,
35b05c51 1525halving the frame rate and preserving image height. A vertical lowpass filter
c91488ab 1526is always applied in order to avoid twitter effects and reduce moiré patterns.
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1527
1528@example
1529 Original Original New Frame
1530 Frame 'j' Frame 'j+1' (tff)
1531 ========== =========== ==================
1532 Line 0 --------------------> Frame 'j' Line 0
1533 Line 1 Line 1 ----> Frame 'j+1' Line 1
1534 Line 2 ---------------------> Frame 'j' Line 2
1535 Line 3 Line 3 ----> Frame 'j+1' Line 3
1536 ... ... ...
1537New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
1538@end example
1539
1540It accepts the following optional parameters:
1541
1542@table @option
1543@item scan
1544determines whether the interlaced frame is taken from the even (tff - default)
1545or odd (bff) lines of the progressive frame.
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1546@end table
1547
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1548@section lut, lutrgb, lutyuv
1549
1550Compute a look-up table for binding each pixel component input value
1551to an output value, and apply it to input video.
1552
1553@var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1554to an RGB input video.
1555
20b46f8f 1556These filters accept the following options:
8fe0c527 1557@table @option
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1558@item @var{c0} (first pixel component)
1559@item @var{c1} (second pixel component)
1560@item @var{c2} (third pixel component)
1561@item @var{c3} (fourth pixel component, corresponds to the alpha component)
8fe0c527 1562
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1563@item @var{r} (red component)
1564@item @var{g} (green component)
1565@item @var{b} (blue component)
1566@item @var{a} (alpha component)
8fe0c527 1567
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1568@item @var{y} (Y/luminance component)
1569@item @var{u} (U/Cb component)
1570@item @var{v} (V/Cr component)
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1571@end table
1572
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1573Each of them specifies the expression to use for computing the lookup table for
1574the corresponding pixel component values.
1575
1576The exact component associated to each of the @var{c*} options depends on the
1577format in input.
1578
1579The @var{lut} filter requires either YUV or RGB pixel formats in input,
1580@var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV.
1581
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1582The expressions can contain the following constants and functions:
1583
1584@table @option
1585@item E, PI, PHI
1586the corresponding mathematical approximated values for e
1587(euler number), pi (greek PI), PHI (golden ratio)
1588
1589@item w, h
da9cea77 1590the input width and height
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1591
1592@item val
1593input value for the pixel component
1594
1595@item clipval
1596the input value clipped in the @var{minval}-@var{maxval} range
1597
1598@item maxval
1599maximum value for the pixel component
1600
1601@item minval
1602minimum value for the pixel component
1603
1604@item negval
1605the negated value for the pixel component value clipped in the
1606@var{minval}-@var{maxval} range , it corresponds to the expression
1607"maxval-clipval+minval"
1608
1609@item clip(val)
1610the computed value in @var{val} clipped in the
1611@var{minval}-@var{maxval} range
1612
1613@item gammaval(gamma)
1614the computed gamma correction value of the pixel component value
1615clipped in the @var{minval}-@var{maxval} range, corresponds to the
1616expression
1617"pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1618
1619@end table
1620
1621All expressions default to "val".
1622
1623Some examples follow:
1624@example
1625# negate input video
1626lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1627lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1628
1629# the above is the same as
1630lutrgb="r=negval:g=negval:b=negval"
1631lutyuv="y=negval:u=negval:v=negval"
1632
1633# negate luminance
1634lutyuv=negval
1635
1636# remove chroma components, turns the video into a graytone image
1637lutyuv="u=128:v=128"
1638
1639# apply a luma burning effect
1640lutyuv="y=2*val"
1641
1642# remove green and blue components
1643lutrgb="g=0:b=0"
1644
1645# set a constant alpha channel value on input
1646format=rgba,lutrgb=a="maxval-minval/2"
1647
1648# correct luminance gamma by a 0.5 factor
1649lutyuv=y=gammaval(0.5)
1650@end example
1651
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1652@section negate
1653
1654Negate input video.
1655
1656This filter accepts an integer in input, if non-zero it negates the
1657alpha component (if available). The default value in input is 0.
3275ac6a 1658
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1659@section noformat
1660
3275ac6a
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1661Force libavfilter not to use any of the specified pixel formats for the
1662input to the next filter.
1663
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1664This filter accepts the following parameters:
1665@table @option
1666
1667@item pix_fmts
1668A '|'-separated list of pixel format names, for example
1669"pix_fmts=yuv420p|monow|rgb24".
1670
1671@end table
3275ac6a 1672
f150e4dc 1673Some examples follow:
3275ac6a 1674@example
f150e4dc
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1675# force libavfilter to use a format different from "yuv420p" for the
1676# input to the vflip filter
e67a87ea 1677noformat=pix_fmts=yuv420p,vflip
3275ac6a 1678
f150e4dc 1679# convert the input video to any of the formats not contained in the list
e67a87ea 1680noformat=yuv420p|yuv444p|yuv410p
f150e4dc 1681@end example
3275ac6a
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1682
1683@section null
1684
99046339 1685Pass the video source unchanged to the output.
3275ac6a 1686
cf69ad35 1687@section ocv
6ebf0bfc 1688
cf69ad35 1689Apply video transform using libopencv.
6ebf0bfc
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1690
1691To enable this filter install libopencv library and headers and
f8a45fa1 1692configure Libav with --enable-libopencv.
6ebf0bfc 1693
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1694This filter accepts the following parameters:
1695
1696@table @option
cf69ad35 1697
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1698@item filter_name
1699The name of the libopencv filter to apply.
cf69ad35 1700
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1701@item filter_params
1702The parameters to pass to the libopencv filter. If not specified the default
1703values are assumed.
1704
1705@end table
cf69ad35
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1706
1707Refer to the official libopencv documentation for more precise
da9cea77 1708information:
cf69ad35
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1709@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1710
1711Follows the list of supported libopencv filters.
1712
17fc9493 1713@anchor{dilate}
91cbb6ba
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1714@subsection dilate
1715
1716Dilate an image by using a specific structuring element.
1717This filter corresponds to the libopencv function @code{cvDilate}.
1718
ee0e8d4b 1719It accepts the parameters: @var{struct_el}|@var{nb_iterations}.
91cbb6ba
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1720
1721@var{struct_el} represents a structuring element, and has the syntax:
1722@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1723
da9cea77 1724@var{cols} and @var{rows} represent the number of columns and rows of
91cbb6ba
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1725the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1726point, and @var{shape} the shape for the structuring element, and
1727can be one of the values "rect", "cross", "ellipse", "custom".
1728
1729If the value for @var{shape} is "custom", it must be followed by a
1730string of the form "=@var{filename}". The file with name
1731@var{filename} is assumed to represent a binary image, with each
1732printable character corresponding to a bright pixel. When a custom
1733@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1734or columns and rows of the read file are assumed instead.
1735
1736The default value for @var{struct_el} is "3x3+0x0/rect".
1737
1738@var{nb_iterations} specifies the number of times the transform is
1739applied to the image, and defaults to 1.
1740
1741Follow some example:
1742@example
1743# use the default values
1744ocv=dilate
1745
1746# dilate using a structuring element with a 5x5 cross, iterate two times
ee0e8d4b 1747ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
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1748
1749# read the shape from the file diamond.shape, iterate two times
1750# the file diamond.shape may contain a pattern of characters like this:
1751# *
1752# ***
1753# *****
1754# ***
1755# *
1756# the specified cols and rows are ignored (but not the anchor point coordinates)
ee0e8d4b 1757ocv=dilate:0x0+2x2/custom=diamond.shape|2
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1758@end example
1759
17fc9493
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1760@subsection erode
1761
1762Erode an image by using a specific structuring element.
1763This filter corresponds to the libopencv function @code{cvErode}.
1764
1765The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4c989761 1766with the same syntax and semantics as the @ref{dilate} filter.
17fc9493 1767
cf69ad35
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1768@subsection smooth
1769
1770Smooth the input video.
1771
1772The filter takes the following parameters:
ee0e8d4b 1773@var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}.
6ebf0bfc
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1774
1775@var{type} is the type of smooth filter to apply, and can be one of
58d94364 1776the following values: "blur", "blur_no_scale", "median", "gaussian",
6ebf0bfc
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1777"bilateral". The default value is "gaussian".
1778
1779@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1780parameters whose meanings depend on smooth type. @var{param1} and
1781@var{param2} accept integer positive values or 0, @var{param3} and
1782@var{param4} accept float values.
1783
1784The default value for @var{param1} is 3, the default value for the
1785other parameters is 0.
1786
58d94364 1787These parameters correspond to the parameters assigned to the
cf69ad35 1788libopencv function @code{cvSmooth}.
6ebf0bfc 1789
2cf74eca 1790@anchor{overlay}
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1791@section overlay
1792
1793Overlay one video on top of another.
1794
1795It takes two inputs and one output, the first input is the "main"
1796video on which the second input is overlayed.
1797
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1798This filter accepts the following parameters:
1799
1800@table @option
1801
1802@item x
1803The horizontal position of the left edge of the overlaid video on the main video.
1804
1805@item y
1806The vertical position of the top edge of the overlaid video on the main video.
1807
1808@end table
58935b25 1809
9087eaf1 1810The parameters are expressions containing the following parameters:
58935b25
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1811
1812@table @option
1813@item main_w, main_h
1814main input width and height
1815
1816@item W, H
1817same as @var{main_w} and @var{main_h}
1818
1819@item overlay_w, overlay_h
1820overlay input width and height
1821
1822@item w, h
1823same as @var{overlay_w} and @var{overlay_h}
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1824
1825@item eof_action
1826The action to take when EOF is encountered on the secondary input, accepts one
1827of the following values:
1828
1829@table @option
1830@item repeat
1831repeat the last frame (the default)
1832@item endall
1833end both streams
1834@item pass
1835pass through the main input
1836@end table
1837
58935b25
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1838@end table
1839
1840Be aware that frames are taken from each input video in timestamp
1841order, hence, if their initial timestamps differ, it is a a good idea
1842to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1843have them begin in the same zero timestamp, as it does the example for
1844the @var{movie} filter.
1845
1846Follow some examples:
1847@example
1848# draw the overlay at 10 pixels from the bottom right
1849# corner of the main video.
9087eaf1 1850overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
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1851
1852# insert a transparent PNG logo in the bottom left corner of the input
9087eaf1 1853avconv -i input -i logo -filter_complex 'overlay=x=10:y=main_h-overlay_h-10' output
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1854
1855# insert 2 different transparent PNG logos (second logo on bottom
1856# right corner):
7ce118ba 1857avconv -i input -i logo1 -i logo2 -filter_complex
9087eaf1 1858'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
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1859
1860# add a transparent color layer on top of the main video,
1861# WxH specifies the size of the main input to the overlay filter
1862color=red@.3:WxH [over]; [in][over] overlay [out]
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1863
1864# mask 10-20 seconds of a video by applying the delogo filter to a section
1865avconv -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
1866-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]'
1867masked.avi
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1868@end example
1869
b0641ab7 1870You can chain together more overlays but the efficiency of such
58935b25
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1871approach is yet to be tested.
1872
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1873@section pad
1874
1875Add paddings to the input image, and places the original input at the
1876given coordinates @var{x}, @var{y}.
1877
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1878This filter accepts the following parameters:
1879
1880@table @option
1881@item width, height
1882
1883Specify the size of the output image with the paddings added. If the
1884value for @var{width} or @var{height} is 0, the corresponding input size
1885is used for the output.
1886
1887The @var{width} expression can reference the value set by the
1888@var{height} expression, and vice versa.
1889
1890The default value of @var{width} and @var{height} is 0.
1891
1892@item x, y
1893
1894Specify the offsets where to place the input image in the padded area
1895with respect to the top/left border of the output image.
1896
1897The @var{x} expression can reference the value set by the @var{y}
1898expression, and vice versa.
1899
1900The default value of @var{x} and @var{y} is 0.
1901
1902@item color
1903
1904Specify the color of the padded area, it can be the name of a color
1905(case insensitive match) or a 0xRRGGBB[AA] sequence.
1906
1907The default value of @var{color} is "black".
1908
1909@end table
3275ac6a 1910
73a4f7c2
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1911The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1912expressions containing the following constants:
1913
1914@table @option
1915@item E, PI, PHI
1916the corresponding mathematical approximated values for e
1917(euler number), pi (greek PI), phi (golden ratio)
1918
1919@item in_w, in_h
e83c2dde 1920the input video width and height
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1921
1922@item iw, ih
1923same as @var{in_w} and @var{in_h}
1924
1925@item out_w, out_h
e83c2dde 1926the output width and height, that is the size of the padded area as
73a4f7c2
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1927specified by the @var{width} and @var{height} expressions
1928
1929@item ow, oh
1930same as @var{out_w} and @var{out_h}
1931
1932@item x, y
1933x and y offsets as specified by the @var{x} and @var{y}
1934expressions, or NAN if not yet specified
1935
1936@item a
1937input display aspect ratio, same as @var{iw} / @var{ih}
1938
1939@item hsub, vsub
1940horizontal and vertical chroma subsample values. For example for the
1941pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1942@end table
1943
73a4f7c2 1944Some examples follow:
3d17f4b9
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1945
1946@example
1947# Add paddings with color "violet" to the input video. Output video
1948# size is 640x480, the top-left corner of the input video is placed at
aeefbf61 1949# column 0, row 40.
40c885c5 1950pad=width=640:height=480:x=0:y=40:color=violet
73a4f7c2
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1951
1952# pad the input to get an output with dimensions increased bt 3/2,
1953# and put the input video at the center of the padded area
1954pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1955
1956# pad the input to get a squared output with size equal to the maximum
1957# value between the input width and height, and put the input video at
1958# the center of the padded area
1959pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1960
1961# pad the input to get a final w/h ratio of 16:9
1962pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1963
1964# double output size and put the input video in the bottom-right
1965# corner of the output padded area
1966pad="2*iw:2*ih:ow-iw:oh-ih"
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1967@end example
1968
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1969@section pixdesctest
1970
1971Pixel format descriptor test filter, mainly useful for internal
1972testing. The output video should be equal to the input video.
1973
1974For example:
1975@example
1976format=monow, pixdesctest
1977@end example
1978
1979can be used to test the monowhite pixel format descriptor definition.
1980
dd249245 1981@anchor{scale}
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1982@section scale
1983
c334c113 1984Scale the input video and/or convert the image format.
3275ac6a 1985
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1986This filter accepts the following options:
1987
1988@table @option
1989
1990@item w
1991Output video width.
1992
1993@item h
1994Output video height.
1995
1996@end table
1997
1998The parameters @var{w} and @var{h} are expressions containing
68e23c08 1999the following constants:
3275ac6a 2000
68e23c08
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2001@table @option
2002@item E, PI, PHI
2003the corresponding mathematical approximated values for e
2004(euler number), pi (greek PI), phi (golden ratio)
2005
2006@item in_w, in_h
e83c2dde 2007the input width and height
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2008
2009@item iw, ih
2010same as @var{in_w} and @var{in_h}
2011
2012@item out_w, out_h
e83c2dde 2013the output (cropped) width and height
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2014
2015@item ow, oh
2016same as @var{out_w} and @var{out_h}
3275ac6a 2017
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2018@item a
2019same as @var{iw} / @var{ih}
68e23c08 2020
46b29397
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2021@item sar
2022input sample aspect ratio
2023
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2024@item dar
2025input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
2026
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2027@item hsub, vsub
2028horizontal and vertical chroma subsample values. For example for the
2029pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2030@end table
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SS
2031
2032If the input image format is different from the format requested by
2033the next filter, the scale filter will convert the input to the
2034requested format.
2035
c334c113 2036If the value for @var{w} or @var{h} is 0, the respective input
3275ac6a
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2037size is used for the output.
2038
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2039If the value for @var{w} or @var{h} is -1, the scale filter will use, for the
2040respective output size, a value that maintains the aspect ratio of the input
2041image.
3275ac6a 2042
c334c113 2043The default value of @var{w} and @var{h} is 0.
3275ac6a 2044
68e23c08
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2045Some examples follow:
2046@example
2047# scale the input video to a size of 200x100.
c334c113 2048scale=w=200:h=100
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2049
2050# scale the input to 2x
c334c113 2051scale=w=2*iw:h=2*ih
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2052# the above is the same as
2053scale=2*in_w:2*in_h
2054
2055# scale the input to half size
c334c113 2056scale=w=iw/2:h=ih/2
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SS
2057
2058# increase the width, and set the height to the same size
2059scale=3/2*iw:ow
2060
2061# seek for Greek harmony
2062scale=iw:1/PHI*iw
2063scale=ih*PHI:ih
2064
2065# increase the height, and set the width to 3/2 of the height
c334c113 2066scale=w=3/2*oh:h=3/5*ih
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2067
2068# increase the size, but make the size a multiple of the chroma
2069scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
2070
2071# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
c334c113 2072scale=w='min(500\, iw*3/2):h=-1'
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2073@end example
2074
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2075@section select
2076Select frames to pass in output.
2077
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2078This filter accepts the following options:
2079
2080@table @option
2081
2082@item expr
2083An expression, which is evaluated for each input frame. If the expression is
2084evaluated to a non-zero value, the frame is selected and passed to the output,
2085otherwise it is discarded.
2086
2087@end table
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2088
2089The expression can contain the following constants:
2090
2091@table @option
2092@item PI
2093Greek PI
2094
2095@item PHI
2096golden ratio
2097
2098@item E
2099Euler number
2100
2101@item n
2102the sequential number of the filtered frame, starting from 0
2103
2104@item selected_n
2105the sequential number of the selected frame, starting from 0
2106
2107@item prev_selected_n
2108the sequential number of the last selected frame, NAN if undefined
2109
2110@item TB
2111timebase of the input timestamps
2112
2113@item pts
2114the PTS (Presentation TimeStamp) of the filtered video frame,
2115expressed in @var{TB} units, NAN if undefined
2116
2117@item t
2118the PTS (Presentation TimeStamp) of the filtered video frame,
2119expressed in seconds, NAN if undefined
2120
2121@item prev_pts
2122the PTS of the previously filtered video frame, NAN if undefined
2123
2124@item prev_selected_pts
2125the PTS of the last previously filtered video frame, NAN if undefined
2126
2127@item prev_selected_t
2128the PTS of the last previously selected video frame, NAN if undefined
2129
2130@item start_pts
2131the PTS of the first video frame in the video, NAN if undefined
2132
2133@item start_t
2134the time of the first video frame in the video, NAN if undefined
2135
2136@item pict_type
2137the type of the filtered frame, can assume one of the following
2138values:
2139@table @option
2140@item I
2141@item P
2142@item B
2143@item S
2144@item SI
2145@item SP
2146@item BI
2147@end table
2148
2149@item interlace_type
2150the frame interlace type, can assume one of the following values:
2151@table @option
2152@item PROGRESSIVE
2153the frame is progressive (not interlaced)
2154@item TOPFIRST
2155the frame is top-field-first
2156@item BOTTOMFIRST
2157the frame is bottom-field-first
2158@end table
2159
2160@item key
21611 if the filtered frame is a key-frame, 0 otherwise
2162
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2163@end table
2164
2165The default value of the select expression is "1".
2166
2167Some examples follow:
2168
2169@example
2170# select all frames in input
2171select
2172
2173# the above is the same as:
95f1f56a 2174select=expr=1
d763fb7d
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2175
2176# skip all frames:
95f1f56a 2177select=expr=0
d763fb7d
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2178
2179# select only I-frames
95f1f56a 2180select='expr=eq(pict_type\,I)'
d763fb7d
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2181
2182# select one frame every 100
2183select='not(mod(n\,100))'
2184
2185# select only frames contained in the 10-20 time interval
2186select='gte(t\,10)*lte(t\,20)'
2187
2188# select only I frames contained in the 10-20 time interval
2189select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2190
2191# select frames with a minimum distance of 10 seconds
2192select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2193@end example
2194
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2195@anchor{setdar}
2196@section setdar
2197
2198Set the Display Aspect Ratio for the filter output video.
2199
2200This is done by changing the specified Sample (aka Pixel) Aspect
2201Ratio, according to the following equation:
2202@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2203
2204Keep in mind that this filter does not modify the pixel dimensions of
2205the video frame. Also the display aspect ratio set by this filter may
2206be changed by later filters in the filterchain, e.g. in case of
2207scaling or if another "setdar" or a "setsar" filter is applied.
2208
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2209This filter accepts the following options:
2210
2211@table @option
2212
2213@item dar
34a0ac41 2214Output display aspect ratio.
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2215
2216@end table
2fd8756b 2217
34a0ac41
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2218The parameter @var{dar} is an expression containing
2219the following constants:
2220
2221@table @option
2222@item E, PI, PHI
2223the corresponding mathematical approximated values for e
2224(euler number), pi (greek PI), phi (golden ratio)
2225
2226@item w, h
2227the input width and height
2228
2229@item a
2230same as @var{w} / @var{h}
2231
2232@item sar
2233input sample aspect ratio
2234
2235@item dar
2236input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2237
2238@item hsub, vsub
2239horizontal and vertical chroma subsample values. For example for the
2240pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2241@end table
2242
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2243For example to change the display aspect ratio to 16:9, specify:
2244@example
2831b307 2245setdar=dar=16/9
2fd8756b 2246# the above is equivalent to
2831b307 2247setdar=dar=1.77777
2fd8756b
SS
2248@end example
2249
4c989761 2250See also the @ref{setsar} filter documentation.
2fd8756b 2251
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2252@section setpts
2253
2254Change the PTS (presentation timestamp) of the input video frames.
2255
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2256This filter accepts the following options:
2257
2258@table @option
2259
2260@item expr
2261The expression which is evaluated for each frame to construct its timestamp.
2262
2263@end table
2264
2265The expression is evaluated through the eval API and can contain the following
2266constants:
a532bb39
SS
2267
2268@table @option
2269@item PTS
2270the presentation timestamp in input
2271
2272@item PI
2273Greek PI
2274
2275@item PHI
2276golden ratio
2277
2278@item E
2279Euler number
2280
2281@item N
2282the count of the input frame, starting from 0.
2283
2284@item STARTPTS
2285the PTS of the first video frame
2286
2287@item INTERLACED
2288tell if the current frame is interlaced
2289
a532bb39
SS
2290@item PREV_INPTS
2291previous input PTS
2292
2293@item PREV_OUTPTS
2294previous output PTS
2295
0b55b16a
VP
2296@item RTCTIME
2297wallclock (RTC) time in microseconds
2298
2299@item RTCSTART
2300wallclock (RTC) time at the start of the movie in microseconds
2301
0ebfdae0
CW
2302@item TB
2303timebase of the input timestamps
2304
a532bb39
SS
2305@end table
2306
2307Some examples follow:
2308
2309@example
2310# start counting PTS from zero
33b97faa 2311setpts=expr=PTS-STARTPTS
a532bb39
SS
2312
2313# fast motion
33b97faa 2314setpts=expr=0.5*PTS
a532bb39
SS
2315
2316# slow motion
2317setpts=2.0*PTS
2318
2319# fixed rate 25 fps
2320setpts=N/(25*TB)
2321
2322# fixed rate 25 fps with some jitter
2323setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
0b55b16a
VP
2324
2325# generate timestamps from a "live source" and rebase onto the current timebase
2326setpts='(RTCTIME - RTCSTART) / (TB * 1000000)"
a532bb39
SS
2327@end example
2328
2fd8756b
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2329@anchor{setsar}
2330@section setsar
2331
2332Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
2333
2334Note that as a consequence of the application of this filter, the
2335output display aspect ratio will change according to the following
2336equation:
2337@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2338
2339Keep in mind that the sample aspect ratio set by this filter may be
2340changed by later filters in the filterchain, e.g. if another "setsar"
2341or a "setdar" filter is applied.
2342
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2343This filter accepts the following options:
2344
2345@table @option
2346
2347@item sar
34a0ac41 2348Output sample aspect ratio.
2831b307
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2349
2350@end table
2fd8756b 2351
34a0ac41
RP
2352The parameter @var{sar} is an expression containing
2353the following constants:
2354
2355@table @option
2356@item E, PI, PHI
2357the corresponding mathematical approximated values for e
2358(euler number), pi (greek PI), phi (golden ratio)
2359
2360@item w, h
2361the input width and height
2362
2363@item a
2364same as @var{w} / @var{h}
2365
2366@item sar
2367input sample aspect ratio
2368
2369@item dar
2370input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
2371
2372@item hsub, vsub
2373horizontal and vertical chroma subsample values. For example for the
2374pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
2375@end table
2376
2fd8756b
SS
2377For example to change the sample aspect ratio to 10:11, specify:
2378@example
2831b307 2379setsar=sar=10/11
2fd8756b
SS
2380@end example
2381
d89e3b36
SS
2382@section settb
2383
2384Set the timebase to use for the output frames timestamps.
2385It is mainly useful for testing timebase configuration.
2386
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2387This filter accepts the following options:
2388
2389@table @option
2390
2391@item expr
2392The expression which is evaluated into the output timebase.
2393
2394@end table
2395
d89e3b36
SS
2396The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
2397default timebase), and "intb" (the input timebase).
2398
2399The default value for the input is "intb".
2400
2401Follow some examples.
2402
2403@example
2404# set the timebase to 1/25
ffea3b00 2405settb=expr=1/25
d89e3b36
SS
2406
2407# set the timebase to 1/10
ffea3b00 2408settb=expr=0.1
d89e3b36
SS
2409
2410#set the timebase to 1001/1000
2411settb=1+0.001
2412
2413#set the timebase to 2*intb
2414settb=2*intb
2415
2416#set the default timebase value
2417settb=AVTB
2418@end example
2419
ee42716b
SS
2420@section showinfo
2421
2422Show a line containing various information for each input video frame.
2423The input video is not modified.
2424
2425The shown line contains a sequence of key/value pairs of the form
2426@var{key}:@var{value}.
2427
2428A description of each shown parameter follows:
2429
2430@table @option
2431@item n
2432sequential number of the input frame, starting from 0
2433
2434@item pts
2435Presentation TimeStamp of the input frame, expressed as a number of
2436time base units. The time base unit depends on the filter input pad.
2437
2438@item pts_time
2439Presentation TimeStamp of the input frame, expressed as a number of
2440seconds
2441
2442@item pos
2443position of the frame in the input stream, -1 if this information in
da9cea77 2444unavailable and/or meaningless (for example in case of synthetic video)
ee42716b
SS
2445
2446@item fmt
2447pixel format name
2448
2449@item sar
2450sample aspect ratio of the input frame, expressed in the form
2451@var{num}/@var{den}
2452
2453@item s
2454size of the input frame, expressed in the form
2455@var{width}x@var{height}
2456
2457@item i
2458interlaced mode ("P" for "progressive", "T" for top field first, "B"
2459for bottom field first)
2460
2461@item iskey
24621 if the frame is a key frame, 0 otherwise
2463
2464@item type
2465picture type of the input frame ("I" for an I-frame, "P" for a
2466P-frame, "B" for a B-frame, "?" for unknown type).
2467Check also the documentation of the @code{AVPictureType} enum and of
2468the @code{av_get_picture_type_char} function defined in
2469@file{libavutil/avutil.h}.
2470
2471@item checksum
2472Adler-32 checksum of all the planes of the input frame
2473
2474@item plane_checksum
2475Adler-32 checksum of each plane of the input frame, expressed in the form
2476"[@var{c0} @var{c1} @var{c2} @var{c3}]"
2477@end table
2478
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2479@section shuffleplanes
2480
2481Reorder and/or duplicate video planes.
2482
2483This filter accepts the following options:
2484
2485@table @option
2486
2487@item map0
2488The index of the input plane to be used as the first output plane.
2489
2490@item map1
2491The index of the input plane to be used as the second output plane.
2492
2493@item map2
2494The index of the input plane to be used as the third output plane.
2495
2496@item map3
2497The index of the input plane to be used as the fourth output plane.
2498
2499@end table
2500
2501The first plane has the index 0. The default is to keep the input unchanged.
2502
2503E.g.
2504@example
2505avconv -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
2506@end example
2507swaps the second and third planes of the input.
2508
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2509@section split
2510
2511Split input video into several identical outputs.
2512
2513The filter accepts a single parameter which specifies the number of outputs. If
2514unspecified, it defaults to 2.
2515
2516For example
2517@example
2518avconv -i INPUT -filter_complex split=5 OUTPUT
2519@end example
2520will create 5 copies of the input video.
2521
43945b27
SS
2522@section transpose
2523
2524Transpose rows with columns in the input video and optionally flip it.
2525
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2526This filter accepts the following options:
2527
2528@table @option
2529
2530@item dir
2531The direction of the transpose.
2532
2533@end table
2534
2535The direction can assume the following values:
43945b27
SS
2536
2537@table @samp
0c2466de 2538@item cclock_flip
43945b27
SS
2539Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2540@example
2541L.R L.l
2542. . -> . .
2543l.r R.r
2544@end example
2545
0c2466de 2546@item clock
43945b27
SS
2547Rotate by 90 degrees clockwise, that is:
2548@example
2549L.R l.L
2550. . -> . .
2551l.r r.R
2552@end example
2553
0c2466de 2554@item cclock
43945b27
SS
2555Rotate by 90 degrees counterclockwise, that is:
2556@example
2557L.R R.r
2558. . -> . .
2559l.r L.l
2560@end example
2561
0c2466de 2562@item clock_flip
43945b27
SS
2563Rotate by 90 degrees clockwise and vertically flip, that is:
2564@example
2565L.R r.R
2566. . -> . .
2567l.r l.L
2568@end example
2569@end table
2570
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2571@section trim
2572Trim the input so that the output contains one continuous subpart of the input.
2573
2574This filter accepts the following options:
2575@table @option
2576@item start
2577Timestamp (in seconds) of the start of the kept section. I.e. the frame with the
2578timestamp @var{start} will be the first frame in the output.
2579
2580@item end
2581Timestamp (in seconds) of the first frame that will be dropped. I.e. the frame
2582immediately preceding the one with the timestamp @var{end} will be the last
2583frame in the output.
2584
2585@item start_pts
2586Same as @var{start}, except this option sets the start timestamp in timebase
2587units instead of seconds.
2588
2589@item end_pts
2590Same as @var{end}, except this option sets the end timestamp in timebase units
2591instead of seconds.
2592
2593@item duration
2594Maximum duration of the output in seconds.
2595
2596@item start_frame
2597Number of the first frame that should be passed to output.
2598
2599@item end_frame
2600Number of the first frame that should be dropped.
2601@end table
2602
2603Note that the first two sets of the start/end options and the @option{duration}
2604option look at the frame timestamp, while the _frame variants simply count the
2605frames that pass through the filter. Also note that this filter does not modify
2606the timestamps. If you wish that the output timestamps start at zero, insert a
2607setpts filter after the trim filter.
2608
2609If multiple start or end options are set, this filter tries to be greedy and
2610keep all the frames that match at least one of the specified constraints. To keep
2611only the part that matches all the constraints at once, chain multiple trim
2612filters.
2613
2614The defaults are such that all the input is kept. So it is possible to set e.g.
2615just the end values to keep everything before the specified time.
2616
2617Examples:
2618@itemize
2619@item
2620drop everything except the second minute of input
2621@example
2622avconv -i INPUT -vf trim=60:120
2623@end example
2624
2625@item
2626keep only the first second
2627@example
2628avconv -i INPUT -vf trim=duration=1
2629@end example
2630
2631@end itemize
3275ac6a
SS
2632@section unsharp
2633
843b5fd0
SS
2634Sharpen or blur the input video.
2635
2636It accepts the following parameters:
3275ac6a
SS
2637
2638@table @option
2639
2640@item luma_msize_x
2641Set the luma matrix horizontal size. It can be an integer between 3
2642and 13, default value is 5.
2643
2644@item luma_msize_y
2645Set the luma matrix vertical size. It can be an integer between 3
2646and 13, default value is 5.
2647
2648@item luma_amount
2649Set the luma effect strength. It can be a float number between -2.0
2650and 5.0, default value is 1.0.
2651
2652@item chroma_msize_x
2653Set the chroma matrix horizontal size. It can be an integer between 3
1ee20141 2654and 13, default value is 5.
3275ac6a
SS
2655
2656@item chroma_msize_y
2657Set the chroma matrix vertical size. It can be an integer between 3
1ee20141 2658and 13, default value is 5.
3275ac6a 2659
2725f2d4 2660@item chroma_amount
3275ac6a
SS
2661Set the chroma effect strength. It can be a float number between -2.0
2662and 5.0, default value is 0.0.
2663
2664@end table
2665
b83e9efc
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2666Negative values for the amount will blur the input video, while positive
2667values will sharpen. All parameters are optional and default to the
2668equivalent of the string '5:5:1.0:5:5:0.0'.
2669
3275ac6a
SS
2670@example
2671# Strong luma sharpen effect parameters
b83e9efc 2672unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
3275ac6a
SS
2673
2674# Strong blur of both luma and chroma parameters
2675unsharp=7:7:-2:7:7:-2
2676
9270b8a3
LB
2677# Use the default values with @command{avconv}
2678./avconv -i in.avi -vf "unsharp" out.mp4
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2679@end example
2680
2681@section vflip
2682
2683Flip the input video vertically.
2684
2685@example
9270b8a3 2686./avconv -i in.avi -vf "vflip" out.avi
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2687@end example
2688
acbac567
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2689@section yadif
2690
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2691Deinterlace the input video ("yadif" means "yet another deinterlacing
2692filter").
acbac567 2693
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2694This filter accepts the following options:
2695
2696@table @option
acbac567 2697
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2698@item mode
2699The interlacing mode to adopt, accepts one of the following values:
acbac567 2700
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2701@table @option
2702@item 0
2703output 1 frame for each frame
2704@item 1
2705output 1 frame for each field
2706@item 2
2707like 0 but skips spatial interlacing check
2708@item 3
2709like 1 but skips spatial interlacing check
2710@end table
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2711
2712Default value is 0.
2713
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2714@item parity
2715The picture field parity assumed for the input interlaced video, accepts one of
2716the following values:
acbac567 2717
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2718@table @option
2719@item 0
1653027a 2720assume top field first
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2721@item 1
2722assume bottom field first
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2723@item -1
2724enable automatic detection
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2725@end table
2726
1653027a 2727Default value is -1.
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2728If interlacing is unknown or decoder does not export this information,
2729top field first will be assumed.
1653027a 2730
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2731@item auto
2732Whether deinterlacer should trust the interlaced flag and only deinterlace
2733frames marked as interlaced
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2734
2735@table @option
2736@item 0
2737deinterlace all frames
2738@item 1
2739only deinterlace frames marked as interlaced
2740@end table
2741
2742Default value is 0.
2743
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2744@end table
2745
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2746@c man end VIDEO FILTERS
2747
2748@chapter Video Sources
2749@c man begin VIDEO SOURCES
2750
2751Below is a description of the currently available video sources.
2752
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2753@section buffer
2754
2755Buffer video frames, and make them available to the filter chain.
2756
2757This source is mainly intended for a programmatic use, in particular
ac1a31ab 2758through the interface defined in @file{libavfilter/vsrc_buffer.h}.
24413399 2759
d28cb849 2760This filter accepts the following parameters:
24413399 2761
d28cb849 2762@table @option
24413399 2763
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2764@item width
2765Input video width.
24413399 2766
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2767@item height
2768Input video height.
24413399 2769
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2770@item pix_fmt
2771Name of the input video pixel format.
24413399 2772
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2773@item time_base
2774The time base used for input timestamps.
24413399 2775
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2776@item sar
2777Sample (pixel) aspect ratio of the input video.
7a11c82f 2778
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2779@end table
2780
2781For example:
2782@example
d28cb849 2783buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
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2784@end example
2785
2786will instruct the source to accept video frames with size 320x240 and
7a11c82f
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2787with format "yuv410p", assuming 1/24 as the timestamps timebase and
2788square pixels (1:1 sample aspect ratio).
24413399 2789
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2790@section color
2791
2792Provide an uniformly colored input.
2793
2794It accepts the following parameters:
23ccf3c7
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2795
2796@table @option
2797
2798@item color
2799Specify the color of the source. It can be the name of a color (case
2800insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2801alpha specifier. The default value is "black".
2802
7bc1a883 2803@item size
23ccf3c7 2804Specify the size of the sourced video, it may be a string of the form
e83c2dde 2805@var{width}x@var{height}, or the name of a size abbreviation. The
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2806default value is "320x240".
2807
7bc1a883 2808@item framerate
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2809Specify the frame rate of the sourced video, as the number of frames
2810generated per second. It has to be a string in the format
2811@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2812number or a valid video frame rate abbreviation. The default value is
2813"25".
2814
2815@end table
2816
2817For example the following graph description will generate a red source
2818with an opacity of 0.2, with size "qcif" and a frame rate of 10
2819frames per second, which will be overlayed over the source connected
2820to the pad with identifier "in".
2821
2822@example
2823"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2824@end example
2825
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2826@section movie
2827
2828Read a video stream from a movie container.
2829
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2830Note that this source is a hack that bypasses the standard input path. It can be
2831useful in applications that do not support arbitrary filter graphs, but its use
2832is discouraged in those that do. Specifically in @command{avconv} this filter
2833should never be used, the @option{-filter_complex} option fully replaces it.
2834
a42d6e6c 2835This filter accepts the following options:
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2836
2837@table @option
2838
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2839@item filename
2840The name of the resource to read (not necessarily a file but also a device or a
2841stream accessed through some protocol).
2842
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2843@item format_name, f
2844Specifies the format assumed for the movie to read, and can be either
2845the name of a container or an input device. If not specified the
2846format is guessed from @var{movie_name} or by probing.
2847
2848@item seek_point, sp
2849Specifies the seek point in seconds, the frames will be output
2850starting from this seek point, the parameter is evaluated with
2851@code{av_strtod} so the numerical value may be suffixed by an IS
2852postfix. Default value is "0".
2853
2854@item stream_index, si
2855Specifies the index of the video stream to read. If the value is -1,
2856the best suited video stream will be automatically selected. Default
2857value is "-1".
2858
2859@end table
2860
2861This filter allows to overlay a second video on top of main input of
2862a filtergraph as shown in this graph:
2863@example
2864input -----------> deltapts0 --> overlay --> output
2865 ^
2866 |
2867movie --> scale--> deltapts1 -------+
2868@end example
2869
2870Some examples follow:
2871@example
2872# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
2873# on top of the input labelled as "in".
2874movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2875[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2876
2877# read from a video4linux2 device, and overlay it on top of the input
2878# labelled as "in"
2879movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2880[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2881
2882@end example
2883
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2884@section nullsrc
2885
2886Null video source, never return images. It is mainly useful as a
2887template and to be employed in analysis / debugging tools.
2888
2889It accepts as optional parameter a string of the form
16134b7c 2890@var{width}:@var{height}:@var{timebase}.
3275ac6a 2891
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2892@var{width} and @var{height} specify the size of the configured
2893source. The default values of @var{width} and @var{height} are
2894respectively 352 and 288 (corresponding to the CIF size format).
2895
2896@var{timebase} specifies an arithmetic expression representing a
2897timebase. The expression can contain the constants "PI", "E", "PHI",
2898"AVTB" (the default timebase), and defaults to the value "AVTB".
3275ac6a 2899
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2900@section frei0r_src
2901
2902Provide a frei0r source.
2903
2904To enable compilation of this filter you need to install the frei0r
f8a45fa1 2905header and configure Libav with --enable-frei0r.
f8608dca 2906
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2907This source accepts the following options:
2908
2909@table @option
2910
2911@item size
2912The size of the video to generate, may be a string of the form
2913@var{width}x@var{height} or a frame size abbreviation.
f8608dca 2914
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2915@item framerate
2916Framerate of the generated video, may be a string of the form
2917@var{num}/@var{den} or a frame rate abbreviation.
2918
2919@item filter_name
2920The name to the frei0r source to load. For more information regarding frei0r and
2921how to set the parameters read the section @ref{frei0r} in the description of
2922the video filters.
2923
2924@item filter_params
2925A '|'-separated list of parameters to pass to the frei0r source.
2926
2927@end table
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2928
2929Some examples follow:
2930@example
2931# generate a frei0r partik0l source with size 200x200 and framerate 10
2932# which is overlayed on the overlay filter main input
5aa1a668 2933frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
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2934@end example
2935
ec2ac927 2936@section rgbtestsrc, testsrc
0244879f 2937
ec2ac927
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2938The @code{rgbtestsrc} source generates an RGB test pattern useful for
2939detecting RGB vs BGR issues. You should see a red, green and blue
2940stripe from top to bottom.
0244879f 2941
ec2ac927
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2942The @code{testsrc} source generates a test video pattern, showing a
2943color pattern, a scrolling gradient and a timestamp. This is mainly
2944intended for testing purposes.
2945
7b3eb745 2946The sources accept the following options:
0244879f
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2947
2948@table @option
2949
2950@item size, s
2951Specify the size of the sourced video, it may be a string of the form
da9cea77 2952@var{width}x@var{height}, or the name of a size abbreviation. The
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2953default value is "320x240".
2954
2955@item rate, r
2956Specify the frame rate of the sourced video, as the number of frames
2957generated per second. It has to be a string in the format
2958@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2959number or a valid video frame rate abbreviation. The default value is
2960"25".
2961
2962@item sar
2963Set the sample aspect ratio of the sourced video.
2964
2965@item duration
2966Set the video duration of the sourced video. The accepted syntax is:
2967@example
2968[-]HH[:MM[:SS[.m...]]]
2969[-]S+[.m...]
2970@end example
2971See also the function @code{av_parse_time()}.
2972
2973If not specified, or the expressed duration is negative, the video is
2974supposed to be generated forever.
2975@end table
2976
2977For example the following:
2978@example
2979testsrc=duration=5.3:size=qcif:rate=10
2980@end example
2981
2982will generate a video with a duration of 5.3 seconds, with size
2983176x144 and a framerate of 10 frames per second.
2984
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2985@c man end VIDEO SOURCES
2986
2987@chapter Video Sinks
2988@c man begin VIDEO SINKS
2989
2990Below is a description of the currently available video sinks.
2991
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2992@section buffersink
2993
2994Buffer video frames, and make them available to the end of the filter
2995graph.
2996
2997This sink is intended for a programmatic use through the interface defined in
2998@file{libavfilter/buffersink.h}.
2999
3275ac6a
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3000@section nullsink
3001
3002Null video sink, do absolutely nothing with the input video. It is
3003mainly useful as a template and to be employed in analysis / debugging
3004tools.
3005
3006@c man end VIDEO SINKS