drawtext: add 'fix_bounds' option on coords fixing
[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
17@section Filtergraph syntax
18
19A filtergraph can be represented using a textual representation, which
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20is recognized by the @code{-vf} and @code{-af} options in @command{avconv}
21and @command{avplay}, and by the @code{av_parse_graph()} function defined in
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22@file{libavfilter/avfiltergraph}.
23
24A filterchain consists of a sequence of connected filters, each one
25connected to the previous one in the sequence. A filterchain is
26represented by a list of ","-separated filter descriptions.
27
28A filtergraph consists of a sequence of filterchains. A sequence of
29filterchains is represented by a list of ";"-separated filterchain
30descriptions.
31
32A filter is represented by a string of the form:
33[@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
34
35@var{filter_name} is the name of the filter class of which the
36described filter is an instance of, and has to be the name of one of
37the filter classes registered in the program.
38The name of the filter class is optionally followed by a string
39"=@var{arguments}".
40
41@var{arguments} is a string which contains the parameters used to
42initialize the filter instance, and are described in the filter
43descriptions below.
44
45The list of arguments can be quoted using the character "'" as initial
46and ending mark, and the character '\' for escaping the characters
47within the quoted text; otherwise the argument string is considered
48terminated when the next special character (belonging to the set
49"[]=;,") is encountered.
50
51The name and arguments of the filter are optionally preceded and
52followed by a list of link labels.
53A link label allows to name a link and associate it to a filter output
54or input pad. The preceding labels @var{in_link_1}
55... @var{in_link_N}, are associated to the filter input pads,
56the following labels @var{out_link_1} ... @var{out_link_M}, are
57associated to the output pads.
58
59When two link labels with the same name are found in the
60filtergraph, a link between the corresponding input and output pad is
61created.
62
63If an output pad is not labelled, it is linked by default to the first
64unlabelled input pad of the next filter in the filterchain.
65For example in the filterchain:
66@example
67nullsrc, split[L1], [L2]overlay, nullsink
68@end example
69the split filter instance has two output pads, and the overlay filter
70instance two input pads. The first output pad of split is labelled
71"L1", the first input pad of overlay is labelled "L2", and the second
72output pad of split is linked to the second input pad of overlay,
73which are both unlabelled.
74
75In a complete filterchain all the unlabelled filter input and output
76pads must be connected. A filtergraph is considered valid if all the
77filter input and output pads of all the filterchains are connected.
78
79Follows a BNF description for the filtergraph syntax:
80@example
81@var{NAME} ::= sequence of alphanumeric characters and '_'
82@var{LINKLABEL} ::= "[" @var{NAME} "]"
83@var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
84@var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
85@var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
86@var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
87@var{FILTERGRAPH} ::= @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
88@end example
89
90@c man end FILTERGRAPH DESCRIPTION
91
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92@chapter Audio Filters
93@c man begin AUDIO FILTERS
94
f8a45fa1 95When you configure your Libav build, you can disable any of the
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96existing filters using --disable-filters.
97The configure output will show the audio filters included in your
98build.
99
100Below is a description of the currently available audio filters.
101
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102@section anull
103
104Pass the audio source unchanged to the output.
105
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106@c man end AUDIO FILTERS
107
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108@chapter Audio Sources
109@c man begin AUDIO SOURCES
110
111Below is a description of the currently available audio sources.
112
113@section anullsrc
114
115Null audio source, never return audio frames. It is mainly useful as a
116template and to be employed in analysis / debugging tools.
117
118It accepts as optional parameter a string of the form
119@var{sample_rate}:@var{channel_layout}.
120
121@var{sample_rate} specify the sample rate, and defaults to 44100.
122
123@var{channel_layout} specify the channel layout, and can be either an
124integer or a string representing a channel layout. The default value
125of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
126
127Check the channel_layout_map definition in
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128@file{libavcodec/audioconvert.c} for the mapping between strings and
129channel layout values.
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130
131Follow some examples:
132@example
133# set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
134anullsrc=48000:4
135
136# same as
137anullsrc=48000:mono
138@end example
139
140@c man end AUDIO SOURCES
141
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142@chapter Audio Sinks
143@c man begin AUDIO SINKS
144
145Below is a description of the currently available audio sinks.
146
147@section anullsink
148
149Null audio sink, do absolutely nothing with the input audio. It is
150mainly useful as a template and to be employed in analysis / debugging
151tools.
152
153@c man end AUDIO SINKS
154
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155@chapter Video Filters
156@c man begin VIDEO FILTERS
157
f8a45fa1 158When you configure your Libav build, you can disable any of the
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159existing filters using --disable-filters.
160The configure output will show the video filters included in your
161build.
162
163Below is a description of the currently available video filters.
164
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165@section blackframe
166
167Detect frames that are (almost) completely black. Can be useful to
168detect chapter transitions or commercials. Output lines consist of
169the frame number of the detected frame, the percentage of blackness,
170the position in the file if known or -1 and the timestamp in seconds.
171
172In order to display the output lines, you need to set the loglevel at
173least to the AV_LOG_INFO value.
174
175The filter accepts the syntax:
176@example
177blackframe[=@var{amount}:[@var{threshold}]]
178@end example
179
180@var{amount} is the percentage of the pixels that have to be below the
181threshold, and defaults to 98.
182
183@var{threshold} is the threshold below which a pixel value is
184considered black, and defaults to 32.
185
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186@section boxblur
187
188Apply boxblur algorithm to the input video.
189
190This filter accepts the parameters:
191@var{luma_power}:@var{luma_radius}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
192
193Chroma and alpha parameters are optional, if not specified they default
194to the corresponding values set for @var{luma_radius} and
195@var{luma_power}.
196
197@var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
198the radius in pixels of the box used for blurring the corresponding
199input plane. They are expressions, and can contain the following
200constants:
201@table @option
202@item w, h
da9cea77 203the input width and height in pixels
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204
205@item cw, ch
206the input chroma image width and height in pixels
207
208@item hsub, vsub
209horizontal and vertical chroma subsample values. For example for the
210pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
211@end table
212
213The radius must be a non-negative number, and must not be greater than
214the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
215and of @code{min(cw,ch)/2} for the chroma planes.
216
217@var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
218how many times the boxblur filter is applied to the corresponding
219plane.
220
221Some examples follow:
222
223@itemize
224
225@item
226Apply a boxblur filter with luma, chroma, and alpha radius
227set to 2:
228@example
229boxblur=2:1
230@end example
231
232@item
233Set luma radius to 2, alpha and chroma radius to 0
234@example
235boxblur=2:1:0:0:0:0
236@end example
237
238@item
239Set luma and chroma radius to a fraction of the video dimension
240@example
241boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
242@end example
243
244@end itemize
245
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246@section copy
247
248Copy the input source unchanged to the output. Mainly useful for
249testing purposes.
250
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251@section crop
252
75b67a8a 253Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
3275ac6a 254
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255The parameters are expressions containing the following constants:
256
257@table @option
258@item E, PI, PHI
259the corresponding mathematical approximated values for e
260(euler number), pi (greek PI), PHI (golden ratio)
261
262@item x, y
263the computed values for @var{x} and @var{y}. They are evaluated for
264each new frame.
265
266@item in_w, in_h
e83c2dde 267the input width and height
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268
269@item iw, ih
270same as @var{in_w} and @var{in_h}
271
272@item out_w, out_h
e83c2dde 273the output (cropped) width and height
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274
275@item ow, oh
276same as @var{out_w} and @var{out_h}
277
278@item n
279the number of input frame, starting from 0
280
281@item pos
282the position in the file of the input frame, NAN if unknown
283
284@item t
285timestamp expressed in seconds, NAN if the input timestamp is unknown
3275ac6a 286
75b67a8a 287@end table
3275ac6a 288
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289The @var{out_w} and @var{out_h} parameters specify the expressions for
290the width and height of the output (cropped) video. They are
291evaluated just at the configuration of the filter.
3275ac6a 292
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293The default value of @var{out_w} is "in_w", and the default value of
294@var{out_h} is "in_h".
2bc05d35 295
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296The expression for @var{out_w} may depend on the value of @var{out_h},
297and the expression for @var{out_h} may depend on @var{out_w}, but they
298cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
299evaluated after @var{out_w} and @var{out_h}.
2bc05d35 300
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301The @var{x} and @var{y} parameters specify the expressions for the
302position of the top-left corner of the output (non-cropped) area. They
303are evaluated for each frame. If the evaluated value is not valid, it
304is approximated to the nearest valid value.
3275ac6a 305
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306The default value of @var{x} is "(in_w-out_w)/2", and the default
307value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
308the center of the input image.
309
310The expression for @var{x} may depend on @var{y}, and the expression
311for @var{y} may depend on @var{x}.
312
313Follow some examples:
3275ac6a 314@example
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315# crop the central input area with size 100x100
316crop=100:100
317
318# crop the central input area with size 2/3 of the input video
319"crop=2/3*in_w:2/3*in_h"
320
321# crop the input video central square
322crop=in_h
323
324# delimit the rectangle with the top-left corner placed at position
325# 100:100 and the right-bottom corner corresponding to the right-bottom
326# corner of the input image.
327crop=in_w-100:in_h-100:100:100
3275ac6a 328
e6dba1d8 329# crop 10 pixels from the left and right borders, and 20 pixels from
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330# the top and bottom borders
331"crop=in_w-2*10:in_h-2*20"
3275ac6a 332
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333# keep only the bottom right quarter of the input image
334"crop=in_w/2:in_h/2:in_w/2:in_h/2"
335
336# crop height for getting Greek harmony
337"crop=in_w:1/PHI*in_w"
338
339# trembling effect
340"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)"
341
e6dba1d8 342# erratic camera effect depending on timestamp
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343"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
344
345# set x depending on the value of y
346"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
347@end example
3275ac6a 348
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349@section cropdetect
350
351Auto-detect crop size.
352
353Calculate necessary cropping parameters and prints the recommended
354parameters through the logging system. The detected dimensions
355correspond to the non-black area of the input video.
356
357It accepts the syntax:
358@example
3699c1f1 359cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
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360@end example
361
362@table @option
363
364@item limit
365Threshold, which can be optionally specified from nothing (0) to
366everything (255), defaults to 24.
367
368@item round
369Value which the width/height should be divisible by, defaults to
37016. The offset is automatically adjusted to center the video. Use 2 to
371get only even dimensions (needed for 4:2:2 video). 16 is best when
372encoding to most video codecs.
373
374@item reset
375Counter that determines after how many frames cropdetect will reset
376the previously detected largest video area and start over to detect
377the current optimal crop area. Defaults to 0.
378
379This can be useful when channel logos distort the video area. 0
380indicates never reset and return the largest area encountered during
381playback.
382@end table
383
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384@section delogo
385
386Suppress a TV station logo by a simple interpolation of the surrounding
387pixels. Just set a rectangle covering the logo and watch it disappear
388(and sometimes something even uglier appear - your mileage may vary).
389
390The filter accepts parameters as a string of the form
391"@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
392@var{key}=@var{value} pairs, separated by ":".
393
394The description of the accepted parameters follows.
395
396@table @option
397
398@item x, y
399Specify the top left corner coordinates of the logo. They must be
400specified.
401
402@item w, h
403Specify the width and height of the logo to clear. They must be
404specified.
405
406@item band, t
407Specify the thickness of the fuzzy edge of the rectangle (added to
408@var{w} and @var{h}). The default value is 4.
409
410@item show
411When set to 1, a green rectangle is drawn on the screen to simplify
412finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
413@var{band} is set to 4. The default value is 0.
414
415@end table
416
417Some examples follow.
418
419@itemize
420
421@item
422Set a rectangle covering the area with top left corner coordinates 0,0
423and size 100x77, setting a band of size 10:
424@example
425delogo=0:0:100:77:10
426@end example
427
428@item
429As the previous example, but use named options:
430@example
431delogo=x=0:y=0:w=100:h=77:band=10
432@end example
433
434@end itemize
435
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436@section drawbox
437
438Draw a colored box on the input image.
439
440It accepts the syntax:
441@example
442drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
443@end example
444
445@table @option
446
447@item x, y
448Specify the top left corner coordinates of the box. Default to 0.
449
450@item width, height
451Specify the width and height of the box, if 0 they are interpreted as
452the input width and height. Default to 0.
453
454@item color
455Specify the color of the box to write, it can be the name of a color
456(case insensitive match) or a 0xRRGGBB[AA] sequence.
457@end table
458
459Follow some examples:
460@example
461# draw a black box around the edge of the input image
462drawbox
463
464# draw a box with color red and an opacity of 50%
465drawbox=10:20:200:60:red@@0.5"
466@end example
467
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468@section drawtext
469
470Draw text string or text from specified file on top of video using the
471libfreetype library.
472
0c50edb7 473To enable compilation of this filter you need to configure Libav with
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474@code{--enable-libfreetype}.
475
476The filter also recognizes strftime() sequences in the provided text
477and expands them accordingly. Check the documentation of strftime().
478
479The filter accepts parameters as a list of @var{key}=@var{value} pairs,
480separated by ":".
481
482The description of the accepted parameters follows.
483
484@table @option
485
486@item fontfile
487The font file to be used for drawing text. Path must be included.
488This parameter is mandatory.
489
490@item text
491The text string to be drawn. The text must be a sequence of UTF-8
492encoded characters.
493This parameter is mandatory if no file is specified with the parameter
494@var{textfile}.
495
496@item textfile
497A text file containing text to be drawn. The text must be a sequence
498of UTF-8 encoded characters.
499
500This parameter is mandatory if no text string is specified with the
501parameter @var{text}.
502
503If both text and textfile are specified, an error is thrown.
504
505@item x, y
506The offsets where text will be drawn within the video frame.
507Relative to the top/left border of the output image.
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508They accept expressions similar to the @ref{overlay} filter:
509@table @option
510
511@item x, y
512the computed values for @var{x} and @var{y}. They are evaluated for
513each new frame.
514
515@item main_w, main_h
516main input width and height
517
518@item W, H
519same as @var{main_w} and @var{main_h}
520
521@item text_w, text_h
522rendered text width and height
523
524@item w, h
525same as @var{text_w} and @var{text_h}
526
527@item n
528the number of frames processed, starting from 0
529
530@item t
531timestamp expressed in seconds, NAN if the input timestamp is unknown
532
533@end table
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534
535The default value of @var{x} and @var{y} is 0.
536
537@item fontsize
538The font size to be used for drawing text.
539The default value of @var{fontsize} is 16.
540
541@item fontcolor
542The color to be used for drawing fonts.
543Either a string (e.g. "red") or in 0xRRGGBB[AA] format
544(e.g. "0xff000033"), possibly followed by an alpha specifier.
545The default value of @var{fontcolor} is "black".
546
547@item boxcolor
548The color to be used for drawing box around text.
549Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
550(e.g. "0xff00ff"), possibly followed by an alpha specifier.
551The default value of @var{boxcolor} is "white".
552
553@item box
554Used to draw a box around text using background color.
555Value should be either 1 (enable) or 0 (disable).
556The default value of @var{box} is 0.
557
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558@item shadowx, shadowy
559The x and y offsets for the text shadow position with respect to the
560position of the text. They can be either positive or negative
561values. Default value for both is "0".
562
563@item shadowcolor
564The color to be used for drawing a shadow behind the drawn text. It
565can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
566form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
567The default value of @var{shadowcolor} is "black".
568
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569@item ft_load_flags
570Flags to be used for loading the fonts.
571
572The flags map the corresponding flags supported by libfreetype, and are
573a combination of the following values:
574@table @var
575@item default
576@item no_scale
577@item no_hinting
578@item render
579@item no_bitmap
580@item vertical_layout
581@item force_autohint
582@item crop_bitmap
583@item pedantic
584@item ignore_global_advance_width
585@item no_recurse
586@item ignore_transform
587@item monochrome
588@item linear_design
589@item no_autohint
590@item end table
591@end table
592
593Default value is "render".
594
595For more information consult the documentation for the FT_LOAD_*
596libfreetype flags.
597
598@item tabsize
599The size in number of spaces to use for rendering the tab.
600Default value is 4.
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601
602@item fix_bounds
603If true, check and fix text coords to avoid clipping.
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604@end table
605
606For example the command:
607@example
608drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
609@end example
610
611will draw "Test Text" with font FreeSerif, using the default values
612for the optional parameters.
613
614The command:
615@example
616drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
617 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
618@end example
619
620will draw 'Test Text' with font FreeSerif of size 24 at position x=100
621and y=50 (counting from the top-left corner of the screen), text is
622yellow with a red box around it. Both the text and the box have an
623opacity of 20%.
624
625Note that the double quotes are not necessary if spaces are not used
626within the parameter list.
627
628For more information about libfreetype, check:
629@url{http://www.freetype.org/}.
630
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631@section fade
632
633Apply fade-in/out effect to input video.
634
635It accepts the parameters:
636@var{type}:@var{start_frame}:@var{nb_frames}
637
638@var{type} specifies if the effect type, can be either "in" for
639fade-in, or "out" for a fade-out effect.
640
641@var{start_frame} specifies the number of the start frame for starting
642to apply the fade effect.
643
644@var{nb_frames} specifies the number of frames for which the fade
645effect has to last. At the end of the fade-in effect the output video
646will have the same intensity as the input video, at the end of the
647fade-out transition the output video will be completely black.
648
649A few usage examples follow, usable too as test scenarios.
650@example
651# fade in first 30 frames of video
652fade=in:0:30
653
654# fade out last 45 frames of a 200-frame video
655fade=out:155:45
656
657# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
658fade=in:0:25, fade=out:975:25
659
660# make first 5 frames black, then fade in from frame 5-24
661fade=in:5:20
662@end example
663
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664@section fieldorder
665
666Transform the field order of the input video.
667
668It accepts one parameter which specifies the required field order that
669the input interlaced video will be transformed to. The parameter can
670assume one of the following values:
671
672@table @option
673@item 0 or bff
674output bottom field first
675@item 1 or tff
676output top field first
677@end table
678
679Default value is "tff".
680
681Transformation is achieved by shifting the picture content up or down
682by one line, and filling the remaining line with appropriate picture content.
683This method is consistent with most broadcast field order converters.
684
685If the input video is not flagged as being interlaced, or it is already
686flagged as being of the required output field order then this filter does
687not alter the incoming video.
688
689This filter is very useful when converting to or from PAL DV material,
690which is bottom field first.
691
692For example:
693@example
9270b8a3 694./avconv -i in.vob -vf "fieldorder=bff" out.dv
2f84bb42
MH
695@end example
696
7f1af825
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697@section fifo
698
699Buffer input images and send them when they are requested.
700
701This filter is mainly useful when auto-inserted by the libavfilter
702framework.
703
704The filter does not take parameters.
705
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706@section format
707
708Convert the input video to one of the specified pixel formats.
709Libavfilter will try to pick one that is supported for the input to
710the next filter.
711
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712The filter accepts a list of pixel format names, separated by ":",
713for example "yuv420p:monow:rgb24".
3275ac6a 714
f150e4dc 715Some examples follow:
3275ac6a 716@example
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717# convert the input video to the format "yuv420p"
718format=yuv420p
3275ac6a 719
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720# convert the input video to any of the formats in the list
721format=yuv420p:yuv444p:yuv410p
722@end example
3275ac6a 723
f8608dca 724@anchor{frei0r}
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725@section frei0r
726
727Apply a frei0r effect to the input video.
728
729To enable compilation of this filter you need to install the frei0r
f8a45fa1 730header and configure Libav with --enable-frei0r.
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731
732The filter supports the syntax:
733@example
f51aeedd 734@var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
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735@end example
736
737@var{filter_name} is the name to the frei0r effect to load. If the
738environment variable @env{FREI0R_PATH} is defined, the frei0r effect
739is searched in each one of the directories specified by the colon
740separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
741paths, which are in this order: @file{HOME/.frei0r-1/lib/},
742@file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
743
744@var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
745for the frei0r effect.
746
747A frei0r effect parameter can be a boolean (whose values are specified
748with "y" and "n"), a double, a color (specified by the syntax
749@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
750numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
751description), a position (specified by the syntax @var{X}/@var{Y},
752@var{X} and @var{Y} being float numbers) and a string.
753
754The number and kind of parameters depend on the loaded effect. If an
755effect parameter is not specified the default value is set.
756
757Some examples follow:
758@example
759# apply the distort0r effect, set the first two double parameters
760frei0r=distort0r:0.5:0.01
761
762# apply the colordistance effect, takes a color as first parameter
763frei0r=colordistance:0.2/0.3/0.4
764frei0r=colordistance:violet
765frei0r=colordistance:0x112233
766
767# apply the perspective effect, specify the top left and top right
768# image positions
769frei0r=perspective:0.2/0.2:0.8/0.2
770@end example
771
772For more information see:
773@url{http://piksel.org/frei0r}
774
d5f187fd
N
775@section gradfun
776
777Fix the banding artifacts that are sometimes introduced into nearly flat
778regions by truncation to 8bit colordepth.
779Interpolate the gradients that should go where the bands are, and
780dither them.
781
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782This filter is designed for playback only. Do not use it prior to
783lossy compression, because compression tends to lose the dither and
784bring back the bands.
785
d5f187fd
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786The filter takes two optional parameters, separated by ':':
787@var{strength}:@var{radius}
788
789@var{strength} is the maximum amount by which the filter will change
790any one pixel. Also the threshold for detecting nearly flat
791regions. Acceptable values range from .51 to 255, default value is
7921.2, out-of-range values will be clipped to the valid range.
793
794@var{radius} is the neighborhood to fit the gradient to. A larger
795radius makes for smoother gradients, but also prevents the filter from
796modifying the pixels near detailed regions. Acceptable values are
7978-32, default value is 16, out-of-range values will be clipped to the
798valid range.
799
800@example
801# default parameters
802gradfun=1.2:16
803
804# omitting radius
805gradfun=1.2
806@end example
807
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808@section hflip
809
810Flip the input video horizontally.
811
9270b8a3 812For example to horizontally flip the input video with @command{avconv}:
a1e171df 813@example
9270b8a3 814avconv -i in.avi -vf "hflip" out.avi
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815@end example
816
a4dc7aa5
BC
817@section hqdn3d
818
819High precision/quality 3d denoise filter. This filter aims to reduce
820image noise producing smooth images and making still images really
821still. It should enhance compressibility.
822
823It accepts the following optional parameters:
824@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
825
826@table @option
827@item luma_spatial
828a non-negative float number which specifies spatial luma strength,
829defaults to 4.0
830
831@item chroma_spatial
832a non-negative float number which specifies spatial chroma strength,
833defaults to 3.0*@var{luma_spatial}/4.0
834
835@item luma_tmp
836a float number which specifies luma temporal strength, defaults to
8376.0*@var{luma_spatial}/4.0
838
839@item chroma_tmp
840a float number which specifies chroma temporal strength, defaults to
841@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
842@end table
843
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844@section lut, lutrgb, lutyuv
845
846Compute a look-up table for binding each pixel component input value
847to an output value, and apply it to input video.
848
849@var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
850to an RGB input video.
851
852These filters accept in input a ":"-separated list of options, which
853specify the expressions used for computing the lookup table for the
854corresponding pixel component values.
855
856The @var{lut} filter requires either YUV or RGB pixel formats in
857input, and accepts the options:
858@table @option
859@var{c0} (first pixel component)
860@var{c1} (second pixel component)
861@var{c2} (third pixel component)
862@var{c3} (fourth pixel component, corresponds to the alpha component)
863@end table
864
865The exact component associated to each option depends on the format in
866input.
867
868The @var{lutrgb} filter requires RGB pixel formats in input, and
869accepts the options:
870@table @option
871@var{r} (red component)
872@var{g} (green component)
873@var{b} (blue component)
874@var{a} (alpha component)
875@end table
876
877The @var{lutyuv} filter requires YUV pixel formats in input, and
878accepts the options:
879@table @option
880@var{y} (Y/luminance component)
881@var{u} (U/Cb component)
882@var{v} (V/Cr component)
883@var{a} (alpha component)
884@end table
885
886The expressions can contain the following constants and functions:
887
888@table @option
889@item E, PI, PHI
890the corresponding mathematical approximated values for e
891(euler number), pi (greek PI), PHI (golden ratio)
892
893@item w, h
da9cea77 894the input width and height
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895
896@item val
897input value for the pixel component
898
899@item clipval
900the input value clipped in the @var{minval}-@var{maxval} range
901
902@item maxval
903maximum value for the pixel component
904
905@item minval
906minimum value for the pixel component
907
908@item negval
909the negated value for the pixel component value clipped in the
910@var{minval}-@var{maxval} range , it corresponds to the expression
911"maxval-clipval+minval"
912
913@item clip(val)
914the computed value in @var{val} clipped in the
915@var{minval}-@var{maxval} range
916
917@item gammaval(gamma)
918the computed gamma correction value of the pixel component value
919clipped in the @var{minval}-@var{maxval} range, corresponds to the
920expression
921"pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
922
923@end table
924
925All expressions default to "val".
926
927Some examples follow:
928@example
929# negate input video
930lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
931lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
932
933# the above is the same as
934lutrgb="r=negval:g=negval:b=negval"
935lutyuv="y=negval:u=negval:v=negval"
936
937# negate luminance
938lutyuv=negval
939
940# remove chroma components, turns the video into a graytone image
941lutyuv="u=128:v=128"
942
943# apply a luma burning effect
944lutyuv="y=2*val"
945
946# remove green and blue components
947lutrgb="g=0:b=0"
948
949# set a constant alpha channel value on input
950format=rgba,lutrgb=a="maxval-minval/2"
951
952# correct luminance gamma by a 0.5 factor
953lutyuv=y=gammaval(0.5)
954@end example
955
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956@section negate
957
958Negate input video.
959
960This filter accepts an integer in input, if non-zero it negates the
961alpha component (if available). The default value in input is 0.
3275ac6a
SS
962
963Force libavfilter not to use any of the specified pixel formats for the
964input to the next filter.
965
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966The filter accepts a list of pixel format names, separated by ":",
967for example "yuv420p:monow:rgb24".
3275ac6a 968
f150e4dc 969Some examples follow:
3275ac6a 970@example
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SS
971# force libavfilter to use a format different from "yuv420p" for the
972# input to the vflip filter
973noformat=yuv420p,vflip
3275ac6a 974
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SS
975# convert the input video to any of the formats not contained in the list
976noformat=yuv420p:yuv444p:yuv410p
977@end example
3275ac6a
SS
978
979@section null
980
99046339 981Pass the video source unchanged to the output.
3275ac6a 982
cf69ad35 983@section ocv
6ebf0bfc 984
cf69ad35 985Apply video transform using libopencv.
6ebf0bfc
SS
986
987To enable this filter install libopencv library and headers and
f8a45fa1 988configure Libav with --enable-libopencv.
6ebf0bfc 989
cf69ad35
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990The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
991
992@var{filter_name} is the name of the libopencv filter to apply.
993
994@var{filter_params} specifies the parameters to pass to the libopencv
995filter. If not specified the default values are assumed.
996
997Refer to the official libopencv documentation for more precise
da9cea77 998information:
cf69ad35
SS
999@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1000
1001Follows the list of supported libopencv filters.
1002
17fc9493 1003@anchor{dilate}
91cbb6ba
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1004@subsection dilate
1005
1006Dilate an image by using a specific structuring element.
1007This filter corresponds to the libopencv function @code{cvDilate}.
1008
1009It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1010
1011@var{struct_el} represents a structuring element, and has the syntax:
1012@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1013
da9cea77 1014@var{cols} and @var{rows} represent the number of columns and rows of
91cbb6ba
SS
1015the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1016point, and @var{shape} the shape for the structuring element, and
1017can be one of the values "rect", "cross", "ellipse", "custom".
1018
1019If the value for @var{shape} is "custom", it must be followed by a
1020string of the form "=@var{filename}". The file with name
1021@var{filename} is assumed to represent a binary image, with each
1022printable character corresponding to a bright pixel. When a custom
1023@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1024or columns and rows of the read file are assumed instead.
1025
1026The default value for @var{struct_el} is "3x3+0x0/rect".
1027
1028@var{nb_iterations} specifies the number of times the transform is
1029applied to the image, and defaults to 1.
1030
1031Follow some example:
1032@example
1033# use the default values
1034ocv=dilate
1035
1036# dilate using a structuring element with a 5x5 cross, iterate two times
1037ocv=dilate=5x5+2x2/cross:2
1038
1039# read the shape from the file diamond.shape, iterate two times
1040# the file diamond.shape may contain a pattern of characters like this:
1041# *
1042# ***
1043# *****
1044# ***
1045# *
1046# the specified cols and rows are ignored (but not the anchor point coordinates)
1047ocv=0x0+2x2/custom=diamond.shape:2
1048@end example
1049
17fc9493
SS
1050@subsection erode
1051
1052Erode an image by using a specific structuring element.
1053This filter corresponds to the libopencv function @code{cvErode}.
1054
1055The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4c989761 1056with the same syntax and semantics as the @ref{dilate} filter.
17fc9493 1057
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SS
1058@subsection smooth
1059
1060Smooth the input video.
1061
1062The filter takes the following parameters:
6ebf0bfc
SS
1063@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1064
1065@var{type} is the type of smooth filter to apply, and can be one of
58d94364 1066the following values: "blur", "blur_no_scale", "median", "gaussian",
6ebf0bfc
SS
1067"bilateral". The default value is "gaussian".
1068
1069@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1070parameters whose meanings depend on smooth type. @var{param1} and
1071@var{param2} accept integer positive values or 0, @var{param3} and
1072@var{param4} accept float values.
1073
1074The default value for @var{param1} is 3, the default value for the
1075other parameters is 0.
1076
58d94364 1077These parameters correspond to the parameters assigned to the
cf69ad35 1078libopencv function @code{cvSmooth}.
6ebf0bfc 1079
2cf74eca 1080@anchor{overlay}
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SS
1081@section overlay
1082
1083Overlay one video on top of another.
1084
1085It takes two inputs and one output, the first input is the "main"
1086video on which the second input is overlayed.
1087
1088It accepts the parameters: @var{x}:@var{y}.
1089
1090@var{x} is the x coordinate of the overlayed video on the main video,
1091@var{y} is the y coordinate. The parameters are expressions containing
1092the following parameters:
1093
1094@table @option
1095@item main_w, main_h
1096main input width and height
1097
1098@item W, H
1099same as @var{main_w} and @var{main_h}
1100
1101@item overlay_w, overlay_h
1102overlay input width and height
1103
1104@item w, h
1105same as @var{overlay_w} and @var{overlay_h}
1106@end table
1107
1108Be aware that frames are taken from each input video in timestamp
1109order, hence, if their initial timestamps differ, it is a a good idea
1110to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1111have them begin in the same zero timestamp, as it does the example for
1112the @var{movie} filter.
1113
1114Follow some examples:
1115@example
1116# draw the overlay at 10 pixels from the bottom right
1117# corner of the main video.
1118overlay=main_w-overlay_w-10:main_h-overlay_h-10
1119
1120# insert a transparent PNG logo in the bottom left corner of the input
aa8ac53b 1121movie=logo.png [logo];
58935b25
SS
1122[in][logo] overlay=10:main_h-overlay_h-10 [out]
1123
1124# insert 2 different transparent PNG logos (second logo on bottom
1125# right corner):
aa8ac53b
SS
1126movie=logo1.png [logo1];
1127movie=logo2.png [logo2];
58935b25
SS
1128[in][logo1] overlay=10:H-h-10 [in+logo1];
1129[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
1130
1131# add a transparent color layer on top of the main video,
1132# WxH specifies the size of the main input to the overlay filter
1133color=red@.3:WxH [over]; [in][over] overlay [out]
1134@end example
1135
b0641ab7 1136You can chain together more overlays but the efficiency of such
58935b25
SS
1137approach is yet to be tested.
1138
3275ac6a
SS
1139@section pad
1140
1141Add paddings to the input image, and places the original input at the
1142given coordinates @var{x}, @var{y}.
1143
1144It accepts the following parameters:
1145@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1146
73a4f7c2
SS
1147The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1148expressions containing the following constants:
1149
1150@table @option
1151@item E, PI, PHI
1152the corresponding mathematical approximated values for e
1153(euler number), pi (greek PI), phi (golden ratio)
1154
1155@item in_w, in_h
e83c2dde 1156the input video width and height
73a4f7c2
SS
1157
1158@item iw, ih
1159same as @var{in_w} and @var{in_h}
1160
1161@item out_w, out_h
e83c2dde 1162the output width and height, that is the size of the padded area as
73a4f7c2
SS
1163specified by the @var{width} and @var{height} expressions
1164
1165@item ow, oh
1166same as @var{out_w} and @var{out_h}
1167
1168@item x, y
1169x and y offsets as specified by the @var{x} and @var{y}
1170expressions, or NAN if not yet specified
1171
1172@item a
1173input display aspect ratio, same as @var{iw} / @var{ih}
1174
1175@item hsub, vsub
1176horizontal and vertical chroma subsample values. For example for the
1177pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1178@end table
1179
3275ac6a
SS
1180Follows the description of the accepted parameters.
1181
1182@table @option
1183@item width, height
1184
1185Specify the size of the output image with the paddings added. If the
1186value for @var{width} or @var{height} is 0, the corresponding input size
1187is used for the output.
1188
73a4f7c2 1189The @var{width} expression can reference the value set by the
da9cea77 1190@var{height} expression, and vice versa.
73a4f7c2 1191
3275ac6a
SS
1192The default value of @var{width} and @var{height} is 0.
1193
1194@item x, y
1195
1196Specify the offsets where to place the input image in the padded area
1197with respect to the top/left border of the output image.
1198
73a4f7c2 1199The @var{x} expression can reference the value set by the @var{y}
da9cea77 1200expression, and vice versa.
73a4f7c2 1201
3275ac6a
SS
1202The default value of @var{x} and @var{y} is 0.
1203
1204@item color
1205
1206Specify the color of the padded area, it can be the name of a color
1207(case insensitive match) or a 0xRRGGBB[AA] sequence.
1208
b1094275 1209The default value of @var{color} is "black".
3275ac6a
SS
1210
1211@end table
1212
73a4f7c2 1213Some examples follow:
3d17f4b9
SS
1214
1215@example
1216# Add paddings with color "violet" to the input video. Output video
1217# size is 640x480, the top-left corner of the input video is placed at
aeefbf61 1218# column 0, row 40.
3d17f4b9 1219pad=640:480:0:40:violet
73a4f7c2
SS
1220
1221# pad the input to get an output with dimensions increased bt 3/2,
1222# and put the input video at the center of the padded area
1223pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1224
1225# pad the input to get a squared output with size equal to the maximum
1226# value between the input width and height, and put the input video at
1227# the center of the padded area
1228pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1229
1230# pad the input to get a final w/h ratio of 16:9
1231pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1232
1233# double output size and put the input video in the bottom-right
1234# corner of the output padded area
1235pad="2*iw:2*ih:ow-iw:oh-ih"
3d17f4b9
SS
1236@end example
1237
ce2e4ae3
SS
1238@section pixdesctest
1239
1240Pixel format descriptor test filter, mainly useful for internal
1241testing. The output video should be equal to the input video.
1242
1243For example:
1244@example
1245format=monow, pixdesctest
1246@end example
1247
1248can be used to test the monowhite pixel format descriptor definition.
1249
3275ac6a
SS
1250@section scale
1251
1252Scale the input video to @var{width}:@var{height} and/or convert the image format.
1253
68e23c08
SS
1254The parameters @var{width} and @var{height} are expressions containing
1255the following constants:
3275ac6a 1256
68e23c08
SS
1257@table @option
1258@item E, PI, PHI
1259the corresponding mathematical approximated values for e
1260(euler number), pi (greek PI), phi (golden ratio)
1261
1262@item in_w, in_h
e83c2dde 1263the input width and height
68e23c08
SS
1264
1265@item iw, ih
1266same as @var{in_w} and @var{in_h}
1267
1268@item out_w, out_h
e83c2dde 1269the output (cropped) width and height
68e23c08
SS
1270
1271@item ow, oh
1272same as @var{out_w} and @var{out_h}
3275ac6a 1273
46b29397 1274@item dar, a
68e23c08
SS
1275input display aspect ratio, same as @var{iw} / @var{ih}
1276
46b29397
SS
1277@item sar
1278input sample aspect ratio
1279
68e23c08
SS
1280@item hsub, vsub
1281horizontal and vertical chroma subsample values. For example for the
1282pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1283@end table
3275ac6a
SS
1284
1285If the input image format is different from the format requested by
1286the next filter, the scale filter will convert the input to the
1287requested format.
1288
1289If the value for @var{width} or @var{height} is 0, the respective input
1290size is used for the output.
1291
1292If the value for @var{width} or @var{height} is -1, the scale filter will
1293use, for the respective output size, a value that maintains the aspect
1294ratio of the input image.
1295
1296The default value of @var{width} and @var{height} is 0.
1297
68e23c08
SS
1298Some examples follow:
1299@example
1300# scale the input video to a size of 200x100.
1301scale=200:100
1302
1303# scale the input to 2x
1304scale=2*iw:2*ih
1305# the above is the same as
1306scale=2*in_w:2*in_h
1307
1308# scale the input to half size
1309scale=iw/2:ih/2
1310
1311# increase the width, and set the height to the same size
1312scale=3/2*iw:ow
1313
1314# seek for Greek harmony
1315scale=iw:1/PHI*iw
1316scale=ih*PHI:ih
1317
1318# increase the height, and set the width to 3/2 of the height
1319scale=3/2*oh:3/5*ih
1320
1321# increase the size, but make the size a multiple of the chroma
1322scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1323
1324# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1325scale='min(500\, iw*3/2):-1'
1326@end example
1327
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1328@section select
1329Select frames to pass in output.
1330
1331It accepts in input an expression, which is evaluated for each input
1332frame. If the expression is evaluated to a non-zero value, the frame
1333is selected and passed to the output, otherwise it is discarded.
1334
1335The expression can contain the following constants:
1336
1337@table @option
1338@item PI
1339Greek PI
1340
1341@item PHI
1342golden ratio
1343
1344@item E
1345Euler number
1346
1347@item n
1348the sequential number of the filtered frame, starting from 0
1349
1350@item selected_n
1351the sequential number of the selected frame, starting from 0
1352
1353@item prev_selected_n
1354the sequential number of the last selected frame, NAN if undefined
1355
1356@item TB
1357timebase of the input timestamps
1358
1359@item pts
1360the PTS (Presentation TimeStamp) of the filtered video frame,
1361expressed in @var{TB} units, NAN if undefined
1362
1363@item t
1364the PTS (Presentation TimeStamp) of the filtered video frame,
1365expressed in seconds, NAN if undefined
1366
1367@item prev_pts
1368the PTS of the previously filtered video frame, NAN if undefined
1369
1370@item prev_selected_pts
1371the PTS of the last previously filtered video frame, NAN if undefined
1372
1373@item prev_selected_t
1374the PTS of the last previously selected video frame, NAN if undefined
1375
1376@item start_pts
1377the PTS of the first video frame in the video, NAN if undefined
1378
1379@item start_t
1380the time of the first video frame in the video, NAN if undefined
1381
1382@item pict_type
1383the type of the filtered frame, can assume one of the following
1384values:
1385@table @option
1386@item I
1387@item P
1388@item B
1389@item S
1390@item SI
1391@item SP
1392@item BI
1393@end table
1394
1395@item interlace_type
1396the frame interlace type, can assume one of the following values:
1397@table @option
1398@item PROGRESSIVE
1399the frame is progressive (not interlaced)
1400@item TOPFIRST
1401the frame is top-field-first
1402@item BOTTOMFIRST
1403the frame is bottom-field-first
1404@end table
1405
1406@item key
14071 if the filtered frame is a key-frame, 0 otherwise
1408
1409@item pos
1410the position in the file of the filtered frame, -1 if the information
1411is not available (e.g. for synthetic video)
1412@end table
1413
1414The default value of the select expression is "1".
1415
1416Some examples follow:
1417
1418@example
1419# select all frames in input
1420select
1421
1422# the above is the same as:
1423select=1
1424
1425# skip all frames:
1426select=0
1427
1428# select only I-frames
1429select='eq(pict_type\,I)'
1430
1431# select one frame every 100
1432select='not(mod(n\,100))'
1433
1434# select only frames contained in the 10-20 time interval
1435select='gte(t\,10)*lte(t\,20)'
1436
1437# select only I frames contained in the 10-20 time interval
1438select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
1439
1440# select frames with a minimum distance of 10 seconds
1441select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
1442@end example
1443
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1444@anchor{setdar}
1445@section setdar
1446
1447Set the Display Aspect Ratio for the filter output video.
1448
1449This is done by changing the specified Sample (aka Pixel) Aspect
1450Ratio, according to the following equation:
1451@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1452
1453Keep in mind that this filter does not modify the pixel dimensions of
1454the video frame. Also the display aspect ratio set by this filter may
1455be changed by later filters in the filterchain, e.g. in case of
1456scaling or if another "setdar" or a "setsar" filter is applied.
1457
1458The filter accepts a parameter string which represents the wanted
1459display aspect ratio.
1460The parameter can be a floating point number string, or an expression
1461of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1462numerator and denominator of the aspect ratio.
1463If the parameter is not specified, it is assumed the value "0:1".
1464
1465For example to change the display aspect ratio to 16:9, specify:
1466@example
1467setdar=16:9
1468# the above is equivalent to
1469setdar=1.77777
1470@end example
1471
4c989761 1472See also the @ref{setsar} filter documentation.
2fd8756b 1473
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1474@section setpts
1475
1476Change the PTS (presentation timestamp) of the input video frames.
1477
1478Accept in input an expression evaluated through the eval API, which
1479can contain the following constants:
1480
1481@table @option
1482@item PTS
1483the presentation timestamp in input
1484
1485@item PI
1486Greek PI
1487
1488@item PHI
1489golden ratio
1490
1491@item E
1492Euler number
1493
1494@item N
1495the count of the input frame, starting from 0.
1496
1497@item STARTPTS
1498the PTS of the first video frame
1499
1500@item INTERLACED
1501tell if the current frame is interlaced
1502
1503@item POS
1504original position in the file of the frame, or undefined if undefined
1505for the current frame
1506
1507@item PREV_INPTS
1508previous input PTS
1509
1510@item PREV_OUTPTS
1511previous output PTS
1512
1513@end table
1514
1515Some examples follow:
1516
1517@example
1518# start counting PTS from zero
1519setpts=PTS-STARTPTS
1520
1521# fast motion
1522setpts=0.5*PTS
1523
1524# slow motion
1525setpts=2.0*PTS
1526
1527# fixed rate 25 fps
1528setpts=N/(25*TB)
1529
1530# fixed rate 25 fps with some jitter
1531setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1532@end example
1533
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1534@anchor{setsar}
1535@section setsar
1536
1537Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1538
1539Note that as a consequence of the application of this filter, the
1540output display aspect ratio will change according to the following
1541equation:
1542@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1543
1544Keep in mind that the sample aspect ratio set by this filter may be
1545changed by later filters in the filterchain, e.g. if another "setsar"
1546or a "setdar" filter is applied.
1547
1548The filter accepts a parameter string which represents the wanted
1549sample aspect ratio.
1550The parameter can be a floating point number string, or an expression
1551of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1552numerator and denominator of the aspect ratio.
1553If the parameter is not specified, it is assumed the value "0:1".
1554
1555For example to change the sample aspect ratio to 10:11, specify:
1556@example
1557setsar=10:11
1558@end example
1559
d89e3b36
SS
1560@section settb
1561
1562Set the timebase to use for the output frames timestamps.
1563It is mainly useful for testing timebase configuration.
1564
1565It accepts in input an arithmetic expression representing a rational.
1566The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1567default timebase), and "intb" (the input timebase).
1568
1569The default value for the input is "intb".
1570
1571Follow some examples.
1572
1573@example
1574# set the timebase to 1/25
1575settb=1/25
1576
1577# set the timebase to 1/10
1578settb=0.1
1579
1580#set the timebase to 1001/1000
1581settb=1+0.001
1582
1583#set the timebase to 2*intb
1584settb=2*intb
1585
1586#set the default timebase value
1587settb=AVTB
1588@end example
1589
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1590@section showinfo
1591
1592Show a line containing various information for each input video frame.
1593The input video is not modified.
1594
1595The shown line contains a sequence of key/value pairs of the form
1596@var{key}:@var{value}.
1597
1598A description of each shown parameter follows:
1599
1600@table @option
1601@item n
1602sequential number of the input frame, starting from 0
1603
1604@item pts
1605Presentation TimeStamp of the input frame, expressed as a number of
1606time base units. The time base unit depends on the filter input pad.
1607
1608@item pts_time
1609Presentation TimeStamp of the input frame, expressed as a number of
1610seconds
1611
1612@item pos
1613position of the frame in the input stream, -1 if this information in
da9cea77 1614unavailable and/or meaningless (for example in case of synthetic video)
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SS
1615
1616@item fmt
1617pixel format name
1618
1619@item sar
1620sample aspect ratio of the input frame, expressed in the form
1621@var{num}/@var{den}
1622
1623@item s
1624size of the input frame, expressed in the form
1625@var{width}x@var{height}
1626
1627@item i
1628interlaced mode ("P" for "progressive", "T" for top field first, "B"
1629for bottom field first)
1630
1631@item iskey
16321 if the frame is a key frame, 0 otherwise
1633
1634@item type
1635picture type of the input frame ("I" for an I-frame, "P" for a
1636P-frame, "B" for a B-frame, "?" for unknown type).
1637Check also the documentation of the @code{AVPictureType} enum and of
1638the @code{av_get_picture_type_char} function defined in
1639@file{libavutil/avutil.h}.
1640
1641@item checksum
1642Adler-32 checksum of all the planes of the input frame
1643
1644@item plane_checksum
1645Adler-32 checksum of each plane of the input frame, expressed in the form
1646"[@var{c0} @var{c1} @var{c2} @var{c3}]"
1647@end table
1648
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1649@section slicify
1650
1651Pass the images of input video on to next video filter as multiple
1652slices.
1653
1654@example
9270b8a3 1655./avconv -i in.avi -vf "slicify=32" out.avi
3275ac6a
SS
1656@end example
1657
1658The filter accepts the slice height as parameter. If the parameter is
1659not specified it will use the default value of 16.
1660
1661Adding this in the beginning of filter chains should make filtering
1662faster due to better use of the memory cache.
1663
43945b27
SS
1664@section transpose
1665
1666Transpose rows with columns in the input video and optionally flip it.
1667
1668It accepts a parameter representing an integer, which can assume the
1669values:
1670
1671@table @samp
1672@item 0
1673Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1674@example
1675L.R L.l
1676. . -> . .
1677l.r R.r
1678@end example
1679
1680@item 1
1681Rotate by 90 degrees clockwise, that is:
1682@example
1683L.R l.L
1684. . -> . .
1685l.r r.R
1686@end example
1687
1688@item 2
1689Rotate by 90 degrees counterclockwise, that is:
1690@example
1691L.R R.r
1692. . -> . .
1693l.r L.l
1694@end example
1695
1696@item 3
1697Rotate by 90 degrees clockwise and vertically flip, that is:
1698@example
1699L.R r.R
1700. . -> . .
1701l.r l.L
1702@end example
1703@end table
1704
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1705@section unsharp
1706
843b5fd0
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1707Sharpen or blur the input video.
1708
1709It accepts the following parameters:
1710@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
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SS
1711
1712Negative values for the amount will blur the input video, while positive
1713values will sharpen. All parameters are optional and default to the
1ee20141 1714equivalent of the string '5:5:1.0:5:5:0.0'.
3275ac6a
SS
1715
1716@table @option
1717
1718@item luma_msize_x
1719Set the luma matrix horizontal size. It can be an integer between 3
1720and 13, default value is 5.
1721
1722@item luma_msize_y
1723Set the luma matrix vertical size. It can be an integer between 3
1724and 13, default value is 5.
1725
1726@item luma_amount
1727Set the luma effect strength. It can be a float number between -2.0
1728and 5.0, default value is 1.0.
1729
1730@item chroma_msize_x
1731Set the chroma matrix horizontal size. It can be an integer between 3
1ee20141 1732and 13, default value is 5.
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SS
1733
1734@item chroma_msize_y
1735Set the chroma matrix vertical size. It can be an integer between 3
1ee20141 1736and 13, default value is 5.
3275ac6a
SS
1737
1738@item luma_amount
1739Set the chroma effect strength. It can be a float number between -2.0
1740and 5.0, default value is 0.0.
1741
1742@end table
1743
1744@example
1745# Strong luma sharpen effect parameters
1746unsharp=7:7:2.5
1747
1748# Strong blur of both luma and chroma parameters
1749unsharp=7:7:-2:7:7:-2
1750
9270b8a3
LB
1751# Use the default values with @command{avconv}
1752./avconv -i in.avi -vf "unsharp" out.mp4
3275ac6a
SS
1753@end example
1754
1755@section vflip
1756
1757Flip the input video vertically.
1758
1759@example
9270b8a3 1760./avconv -i in.avi -vf "vflip" out.avi
3275ac6a
SS
1761@end example
1762
acbac567
MN
1763@section yadif
1764
1653027a
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1765Deinterlace the input video ("yadif" means "yet another deinterlacing
1766filter").
acbac567 1767
ab09df9d 1768It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
acbac567 1769
1653027a
SS
1770@var{mode} specifies the interlacing mode to adopt, accepts one of the
1771following values:
acbac567 1772
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1773@table @option
1774@item 0
1775output 1 frame for each frame
1776@item 1
1777output 1 frame for each field
1778@item 2
1779like 0 but skips spatial interlacing check
1780@item 3
1781like 1 but skips spatial interlacing check
1782@end table
acbac567
MN
1783
1784Default value is 0.
1785
1653027a
SS
1786@var{parity} specifies the picture field parity assumed for the input
1787interlaced video, accepts one of the following values:
acbac567 1788
1653027a
SS
1789@table @option
1790@item 0
1653027a 1791assume top field first
4703a7b5
SS
1792@item 1
1793assume bottom field first
1653027a
SS
1794@item -1
1795enable automatic detection
acbac567
MN
1796@end table
1797
1653027a 1798Default value is -1.
a51c71bb
BC
1799If interlacing is unknown or decoder does not export this information,
1800top field first will be assumed.
1653027a 1801
b0641ab7 1802@var{auto} specifies if deinterlacer should trust the interlaced flag
ab09df9d
JP
1803and only deinterlace frames marked as interlaced
1804
1805@table @option
1806@item 0
1807deinterlace all frames
1808@item 1
1809only deinterlace frames marked as interlaced
1810@end table
1811
1812Default value is 0.
1813
3275ac6a
SS
1814@c man end VIDEO FILTERS
1815
1816@chapter Video Sources
1817@c man begin VIDEO SOURCES
1818
1819Below is a description of the currently available video sources.
1820
24413399
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1821@section buffer
1822
1823Buffer video frames, and make them available to the filter chain.
1824
1825This source is mainly intended for a programmatic use, in particular
ac1a31ab 1826through the interface defined in @file{libavfilter/vsrc_buffer.h}.
24413399
SS
1827
1828It accepts the following parameters:
7a11c82f 1829@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
24413399 1830
da9cea77 1831All the parameters need to be explicitly defined.
24413399
SS
1832
1833Follows the list of the accepted parameters.
1834
1835@table @option
1836
1837@item width, height
1838Specify the width and height of the buffered video frames.
1839
1840@item pix_fmt_string
24413399
SS
1841A string representing the pixel format of the buffered video frames.
1842It may be a number corresponding to a pixel format, or a pixel format
1843name.
1844
94498ec9
SS
1845@item timebase_num, timebase_den
1846Specify numerator and denomitor of the timebase assumed by the
1847timestamps of the buffered frames.
7a11c82f
MN
1848
1849@item sample_aspect_ratio.num, sample_aspect_ratio.den
1850Specify numerator and denominator of the sample aspect ratio assumed
1851by the video frames.
24413399
SS
1852@end table
1853
1854For example:
1855@example
7a11c82f 1856buffer=320:240:yuv410p:1:24:1:1
24413399
SS
1857@end example
1858
1859will instruct the source to accept video frames with size 320x240 and
7a11c82f
MN
1860with format "yuv410p", assuming 1/24 as the timestamps timebase and
1861square pixels (1:1 sample aspect ratio).
94498ec9
SS
1862Since the pixel format with name "yuv410p" corresponds to the number 6
1863(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1864this example corresponds to:
24413399 1865@example
94498ec9 1866buffer=320:240:6:1:24
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1867@end example
1868
23ccf3c7
SS
1869@section color
1870
1871Provide an uniformly colored input.
1872
1873It accepts the following parameters:
b5f47309 1874@var{color}:@var{frame_size}:@var{frame_rate}
23ccf3c7
SS
1875
1876Follows the description of the accepted parameters.
1877
1878@table @option
1879
1880@item color
1881Specify the color of the source. It can be the name of a color (case
1882insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1883alpha specifier. The default value is "black".
1884
1885@item frame_size
1886Specify the size of the sourced video, it may be a string of the form
e83c2dde 1887@var{width}x@var{height}, or the name of a size abbreviation. The
23ccf3c7
SS
1888default value is "320x240".
1889
1890@item frame_rate
1891Specify the frame rate of the sourced video, as the number of frames
1892generated per second. It has to be a string in the format
1893@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1894number or a valid video frame rate abbreviation. The default value is
1895"25".
1896
1897@end table
1898
1899For example the following graph description will generate a red source
1900with an opacity of 0.2, with size "qcif" and a frame rate of 10
1901frames per second, which will be overlayed over the source connected
1902to the pad with identifier "in".
1903
1904@example
1905"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1906@end example
1907
9409c381
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1908@section movie
1909
1910Read a video stream from a movie container.
1911
1912It accepts the syntax: @var{movie_name}[:@var{options}] where
1913@var{movie_name} is the name of the resource to read (not necessarily
1914a file but also a device or a stream accessed through some protocol),
1915and @var{options} is an optional sequence of @var{key}=@var{value}
1916pairs, separated by ":".
1917
1918The description of the accepted options follows.
1919
1920@table @option
1921
1922@item format_name, f
1923Specifies the format assumed for the movie to read, and can be either
1924the name of a container or an input device. If not specified the
1925format is guessed from @var{movie_name} or by probing.
1926
1927@item seek_point, sp
1928Specifies the seek point in seconds, the frames will be output
1929starting from this seek point, the parameter is evaluated with
1930@code{av_strtod} so the numerical value may be suffixed by an IS
1931postfix. Default value is "0".
1932
1933@item stream_index, si
1934Specifies the index of the video stream to read. If the value is -1,
1935the best suited video stream will be automatically selected. Default
1936value is "-1".
1937
1938@end table
1939
1940This filter allows to overlay a second video on top of main input of
1941a filtergraph as shown in this graph:
1942@example
1943input -----------> deltapts0 --> overlay --> output
1944 ^
1945 |
1946movie --> scale--> deltapts1 -------+
1947@end example
1948
1949Some examples follow:
1950@example
1951# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1952# on top of the input labelled as "in".
1953movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1954[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1955
1956# read from a video4linux2 device, and overlay it on top of the input
1957# labelled as "in"
1958movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1959[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1960
1961@end example
1962
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1963@section nullsrc
1964
1965Null video source, never return images. It is mainly useful as a
1966template and to be employed in analysis / debugging tools.
1967
1968It accepts as optional parameter a string of the form
16134b7c 1969@var{width}:@var{height}:@var{timebase}.
3275ac6a 1970
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1971@var{width} and @var{height} specify the size of the configured
1972source. The default values of @var{width} and @var{height} are
1973respectively 352 and 288 (corresponding to the CIF size format).
1974
1975@var{timebase} specifies an arithmetic expression representing a
1976timebase. The expression can contain the constants "PI", "E", "PHI",
1977"AVTB" (the default timebase), and defaults to the value "AVTB".
3275ac6a 1978
f8608dca
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1979@section frei0r_src
1980
1981Provide a frei0r source.
1982
1983To enable compilation of this filter you need to install the frei0r
f8a45fa1 1984header and configure Libav with --enable-frei0r.
f8608dca
SS
1985
1986The source supports the syntax:
1987@example
1988@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1989@end example
1990
1991@var{size} is the size of the video to generate, may be a string of the
1992form @var{width}x@var{height} or a frame size abbreviation.
1993@var{rate} is the rate of the video to generate, may be a string of
1994the form @var{num}/@var{den} or a frame rate abbreviation.
1995@var{src_name} is the name to the frei0r source to load. For more
1996information regarding frei0r and how to set the parameters read the
4c989761 1997section @ref{frei0r} in the description of the video filters.
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1998
1999Some examples follow:
2000@example
2001# generate a frei0r partik0l source with size 200x200 and framerate 10
2002# which is overlayed on the overlay filter main input
2003frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
2004@end example
2005
ec2ac927 2006@section rgbtestsrc, testsrc
0244879f 2007
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2008The @code{rgbtestsrc} source generates an RGB test pattern useful for
2009detecting RGB vs BGR issues. You should see a red, green and blue
2010stripe from top to bottom.
0244879f 2011
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2012The @code{testsrc} source generates a test video pattern, showing a
2013color pattern, a scrolling gradient and a timestamp. This is mainly
2014intended for testing purposes.
2015
2016Both sources accept an optional sequence of @var{key}=@var{value} pairs,
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2017separated by ":". The description of the accepted options follows.
2018
2019@table @option
2020
2021@item size, s
2022Specify the size of the sourced video, it may be a string of the form
da9cea77 2023@var{width}x@var{height}, or the name of a size abbreviation. The
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2024default value is "320x240".
2025
2026@item rate, r
2027Specify the frame rate of the sourced video, as the number of frames
2028generated per second. It has to be a string in the format
2029@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2030number or a valid video frame rate abbreviation. The default value is
2031"25".
2032
2033@item sar
2034Set the sample aspect ratio of the sourced video.
2035
2036@item duration
2037Set the video duration of the sourced video. The accepted syntax is:
2038@example
2039[-]HH[:MM[:SS[.m...]]]
2040[-]S+[.m...]
2041@end example
2042See also the function @code{av_parse_time()}.
2043
2044If not specified, or the expressed duration is negative, the video is
2045supposed to be generated forever.
2046@end table
2047
2048For example the following:
2049@example
2050testsrc=duration=5.3:size=qcif:rate=10
2051@end example
2052
2053will generate a video with a duration of 5.3 seconds, with size
2054176x144 and a framerate of 10 frames per second.
2055
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2056@c man end VIDEO SOURCES
2057
2058@chapter Video Sinks
2059@c man begin VIDEO SINKS
2060
2061Below is a description of the currently available video sinks.
2062
2063@section nullsink
2064
2065Null video sink, do absolutely nothing with the input video. It is
2066mainly useful as a template and to be employed in analysis / debugging
2067tools.
2068
2069@c man end VIDEO SINKS
2070