lavfi: add lavr-based audio resampling filter.
[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
24@file{libavfilter/avfiltergraph.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
44initialize the filter instance, and are described in the filter
45descriptions below.
46
47The list of arguments can be quoted using the character "'" as initial
48and ending mark, and the character '\' for escaping the characters
49within the quoted text; otherwise the argument string is considered
50terminated when the next special character (belonging to the set
51"[]=;,") is encountered.
52
53The name and arguments of the filter are optionally preceded and
54followed by a list of link labels.
55A link label allows to name a link and associate it to a filter output
56or input pad. The preceding labels @var{in_link_1}
57... @var{in_link_N}, are associated to the filter input pads,
58the following labels @var{out_link_1} ... @var{out_link_M}, are
59associated to the output pads.
60
61When two link labels with the same name are found in the
62filtergraph, a link between the corresponding input and output pad is
63created.
64
65If an output pad is not labelled, it is linked by default to the first
66unlabelled input pad of the next filter in the filterchain.
67For example in the filterchain:
68@example
69nullsrc, split[L1], [L2]overlay, nullsink
70@end example
71the split filter instance has two output pads, and the overlay filter
72instance two input pads. The first output pad of split is labelled
73"L1", the first input pad of overlay is labelled "L2", and the second
74output pad of split is linked to the second input pad of overlay,
75which are both unlabelled.
76
77In a complete filterchain all the unlabelled filter input and output
78pads must be connected. A filtergraph is considered valid if all the
79filter input and output pads of all the filterchains are connected.
80
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81Libavfilter will automatically insert scale filters where format
82conversion is required. It is possible to specify swscale flags
83for those automatically inserted scalers by prepending
84@code{sws_flags=@var{flags};}
85to the filtergraph description.
86
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87Follows a BNF description for the filtergraph syntax:
88@example
89@var{NAME} ::= sequence of alphanumeric characters and '_'
90@var{LINKLABEL} ::= "[" @var{NAME} "]"
91@var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
92@var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
93@var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
94@var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
12e7e1d0 95@var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
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96@end example
97
98@c man end FILTERGRAPH DESCRIPTION
99
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100@chapter Audio Filters
101@c man begin AUDIO FILTERS
102
f8a45fa1 103When you configure your Libav build, you can disable any of the
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104existing filters using --disable-filters.
105The configure output will show the audio filters included in your
106build.
107
108Below is a description of the currently available audio filters.
109
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110@section anull
111
112Pass the audio source unchanged to the output.
113
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114@section resample
115Convert the audio sample format, sample rate and channel layout. This filter is
116not meant to be used directly, it is inserted automatically by libavfilter
117whenever conversion is needed. Use the @var{aformat} filter to force a specific
118conversion.
119
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120@c man end AUDIO FILTERS
121
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122@chapter Audio Sources
123@c man begin AUDIO SOURCES
124
125Below is a description of the currently available audio sources.
126
127@section anullsrc
128
129Null audio source, never return audio frames. It is mainly useful as a
130template and to be employed in analysis / debugging tools.
131
132It accepts as optional parameter a string of the form
133@var{sample_rate}:@var{channel_layout}.
134
135@var{sample_rate} specify the sample rate, and defaults to 44100.
136
137@var{channel_layout} specify the channel layout, and can be either an
138integer or a string representing a channel layout. The default value
139of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
140
141Check the channel_layout_map definition in
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142@file{libavcodec/audioconvert.c} for the mapping between strings and
143channel layout values.
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144
145Follow some examples:
146@example
147# set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
148anullsrc=48000:4
149
150# same as
151anullsrc=48000:mono
152@end example
153
154@c man end AUDIO SOURCES
155
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156@chapter Audio Sinks
157@c man begin AUDIO SINKS
158
159Below is a description of the currently available audio sinks.
160
161@section anullsink
162
163Null audio sink, do absolutely nothing with the input audio. It is
164mainly useful as a template and to be employed in analysis / debugging
165tools.
166
167@c man end AUDIO SINKS
168
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169@chapter Video Filters
170@c man begin VIDEO FILTERS
171
f8a45fa1 172When you configure your Libav build, you can disable any of the
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173existing filters using --disable-filters.
174The configure output will show the video filters included in your
175build.
176
177Below is a description of the currently available video filters.
178
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179@section blackframe
180
181Detect frames that are (almost) completely black. Can be useful to
182detect chapter transitions or commercials. Output lines consist of
183the frame number of the detected frame, the percentage of blackness,
184the position in the file if known or -1 and the timestamp in seconds.
185
186In order to display the output lines, you need to set the loglevel at
187least to the AV_LOG_INFO value.
188
189The filter accepts the syntax:
190@example
191blackframe[=@var{amount}:[@var{threshold}]]
192@end example
193
194@var{amount} is the percentage of the pixels that have to be below the
195threshold, and defaults to 98.
196
197@var{threshold} is the threshold below which a pixel value is
198considered black, and defaults to 32.
199
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200@section boxblur
201
202Apply boxblur algorithm to the input video.
203
204This filter accepts the parameters:
205@var{luma_power}:@var{luma_radius}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
206
207Chroma and alpha parameters are optional, if not specified they default
208to the corresponding values set for @var{luma_radius} and
209@var{luma_power}.
210
211@var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
212the radius in pixels of the box used for blurring the corresponding
213input plane. They are expressions, and can contain the following
214constants:
215@table @option
216@item w, h
da9cea77 217the input width and height in pixels
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218
219@item cw, ch
220the input chroma image width and height in pixels
221
222@item hsub, vsub
223horizontal and vertical chroma subsample values. For example for the
224pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
225@end table
226
227The radius must be a non-negative number, and must not be greater than
228the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
229and of @code{min(cw,ch)/2} for the chroma planes.
230
231@var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
232how many times the boxblur filter is applied to the corresponding
233plane.
234
235Some examples follow:
236
237@itemize
238
239@item
240Apply a boxblur filter with luma, chroma, and alpha radius
241set to 2:
242@example
243boxblur=2:1
244@end example
245
246@item
247Set luma radius to 2, alpha and chroma radius to 0
248@example
249boxblur=2:1:0:0:0:0
250@end example
251
252@item
253Set luma and chroma radius to a fraction of the video dimension
254@example
255boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
256@end example
257
258@end itemize
259
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260@section copy
261
262Copy the input source unchanged to the output. Mainly useful for
263testing purposes.
264
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265@section crop
266
75b67a8a 267Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
3275ac6a 268
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269The parameters are expressions containing the following constants:
270
271@table @option
272@item E, PI, PHI
273the corresponding mathematical approximated values for e
274(euler number), pi (greek PI), PHI (golden ratio)
275
276@item x, y
277the computed values for @var{x} and @var{y}. They are evaluated for
278each new frame.
279
280@item in_w, in_h
e83c2dde 281the input width and height
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282
283@item iw, ih
284same as @var{in_w} and @var{in_h}
285
286@item out_w, out_h
e83c2dde 287the output (cropped) width and height
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288
289@item ow, oh
290same as @var{out_w} and @var{out_h}
291
292@item n
293the number of input frame, starting from 0
294
295@item pos
296the position in the file of the input frame, NAN if unknown
297
298@item t
299timestamp expressed in seconds, NAN if the input timestamp is unknown
3275ac6a 300
75b67a8a 301@end table
3275ac6a 302
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303The @var{out_w} and @var{out_h} parameters specify the expressions for
304the width and height of the output (cropped) video. They are
305evaluated just at the configuration of the filter.
3275ac6a 306
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307The default value of @var{out_w} is "in_w", and the default value of
308@var{out_h} is "in_h".
2bc05d35 309
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310The expression for @var{out_w} may depend on the value of @var{out_h},
311and the expression for @var{out_h} may depend on @var{out_w}, but they
312cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
313evaluated after @var{out_w} and @var{out_h}.
2bc05d35 314
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315The @var{x} and @var{y} parameters specify the expressions for the
316position of the top-left corner of the output (non-cropped) area. They
317are evaluated for each frame. If the evaluated value is not valid, it
318is approximated to the nearest valid value.
3275ac6a 319
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320The default value of @var{x} is "(in_w-out_w)/2", and the default
321value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
322the center of the input image.
323
324The expression for @var{x} may depend on @var{y}, and the expression
325for @var{y} may depend on @var{x}.
326
327Follow some examples:
3275ac6a 328@example
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329# crop the central input area with size 100x100
330crop=100:100
331
332# crop the central input area with size 2/3 of the input video
333"crop=2/3*in_w:2/3*in_h"
334
335# crop the input video central square
336crop=in_h
337
338# delimit the rectangle with the top-left corner placed at position
339# 100:100 and the right-bottom corner corresponding to the right-bottom
340# corner of the input image.
341crop=in_w-100:in_h-100:100:100
3275ac6a 342
e6dba1d8 343# crop 10 pixels from the left and right borders, and 20 pixels from
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344# the top and bottom borders
345"crop=in_w-2*10:in_h-2*20"
3275ac6a 346
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347# keep only the bottom right quarter of the input image
348"crop=in_w/2:in_h/2:in_w/2:in_h/2"
349
350# crop height for getting Greek harmony
351"crop=in_w:1/PHI*in_w"
352
353# trembling effect
354"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)"
355
e6dba1d8 356# erratic camera effect depending on timestamp
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357"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)"
358
359# set x depending on the value of y
360"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
361@end example
3275ac6a 362
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363@section cropdetect
364
365Auto-detect crop size.
366
367Calculate necessary cropping parameters and prints the recommended
368parameters through the logging system. The detected dimensions
369correspond to the non-black area of the input video.
370
371It accepts the syntax:
372@example
3699c1f1 373cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
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374@end example
375
376@table @option
377
378@item limit
379Threshold, which can be optionally specified from nothing (0) to
380everything (255), defaults to 24.
381
382@item round
383Value which the width/height should be divisible by, defaults to
38416. The offset is automatically adjusted to center the video. Use 2 to
385get only even dimensions (needed for 4:2:2 video). 16 is best when
386encoding to most video codecs.
387
388@item reset
389Counter that determines after how many frames cropdetect will reset
390the previously detected largest video area and start over to detect
391the current optimal crop area. Defaults to 0.
392
393This can be useful when channel logos distort the video area. 0
394indicates never reset and return the largest area encountered during
395playback.
396@end table
397
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398@section delogo
399
400Suppress a TV station logo by a simple interpolation of the surrounding
401pixels. Just set a rectangle covering the logo and watch it disappear
402(and sometimes something even uglier appear - your mileage may vary).
403
404The filter accepts parameters as a string of the form
405"@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
406@var{key}=@var{value} pairs, separated by ":".
407
408The description of the accepted parameters follows.
409
410@table @option
411
412@item x, y
413Specify the top left corner coordinates of the logo. They must be
414specified.
415
416@item w, h
417Specify the width and height of the logo to clear. They must be
418specified.
419
420@item band, t
421Specify the thickness of the fuzzy edge of the rectangle (added to
422@var{w} and @var{h}). The default value is 4.
423
424@item show
425When set to 1, a green rectangle is drawn on the screen to simplify
426finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
427@var{band} is set to 4. The default value is 0.
428
429@end table
430
431Some examples follow.
432
433@itemize
434
435@item
436Set a rectangle covering the area with top left corner coordinates 0,0
437and size 100x77, setting a band of size 10:
438@example
439delogo=0:0:100:77:10
440@end example
441
442@item
443As the previous example, but use named options:
444@example
445delogo=x=0:y=0:w=100:h=77:band=10
446@end example
447
448@end itemize
449
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450@section drawbox
451
452Draw a colored box on the input image.
453
454It accepts the syntax:
455@example
456drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
457@end example
458
459@table @option
460
461@item x, y
462Specify the top left corner coordinates of the box. Default to 0.
463
464@item width, height
465Specify the width and height of the box, if 0 they are interpreted as
466the input width and height. Default to 0.
467
468@item color
469Specify the color of the box to write, it can be the name of a color
470(case insensitive match) or a 0xRRGGBB[AA] sequence.
471@end table
472
473Follow some examples:
474@example
475# draw a black box around the edge of the input image
476drawbox
477
478# draw a box with color red and an opacity of 50%
479drawbox=10:20:200:60:red@@0.5"
480@end example
481
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482@section drawtext
483
484Draw text string or text from specified file on top of video using the
485libfreetype library.
486
0c50edb7 487To enable compilation of this filter you need to configure Libav with
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488@code{--enable-libfreetype}.
489
490The filter also recognizes strftime() sequences in the provided text
491and expands them accordingly. Check the documentation of strftime().
492
493The filter accepts parameters as a list of @var{key}=@var{value} pairs,
494separated by ":".
495
496The description of the accepted parameters follows.
497
498@table @option
499
500@item fontfile
501The font file to be used for drawing text. Path must be included.
502This parameter is mandatory.
503
504@item text
505The text string to be drawn. The text must be a sequence of UTF-8
506encoded characters.
507This parameter is mandatory if no file is specified with the parameter
508@var{textfile}.
509
510@item textfile
511A text file containing text to be drawn. The text must be a sequence
512of UTF-8 encoded characters.
513
514This parameter is mandatory if no text string is specified with the
515parameter @var{text}.
516
517If both text and textfile are specified, an error is thrown.
518
519@item x, y
520The offsets where text will be drawn within the video frame.
521Relative to the top/left border of the output image.
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522They accept expressions similar to the @ref{overlay} filter:
523@table @option
524
525@item x, y
526the computed values for @var{x} and @var{y}. They are evaluated for
527each new frame.
528
529@item main_w, main_h
530main input width and height
531
532@item W, H
533same as @var{main_w} and @var{main_h}
534
535@item text_w, text_h
536rendered text width and height
537
538@item w, h
539same as @var{text_w} and @var{text_h}
540
541@item n
542the number of frames processed, starting from 0
543
544@item t
545timestamp expressed in seconds, NAN if the input timestamp is unknown
546
547@end table
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548
549The default value of @var{x} and @var{y} is 0.
550
551@item fontsize
552The font size to be used for drawing text.
553The default value of @var{fontsize} is 16.
554
555@item fontcolor
556The color to be used for drawing fonts.
557Either a string (e.g. "red") or in 0xRRGGBB[AA] format
558(e.g. "0xff000033"), possibly followed by an alpha specifier.
559The default value of @var{fontcolor} is "black".
560
561@item boxcolor
562The color to be used for drawing box around text.
563Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
564(e.g. "0xff00ff"), possibly followed by an alpha specifier.
565The default value of @var{boxcolor} is "white".
566
567@item box
568Used to draw a box around text using background color.
569Value should be either 1 (enable) or 0 (disable).
570The default value of @var{box} is 0.
571
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572@item shadowx, shadowy
573The x and y offsets for the text shadow position with respect to the
574position of the text. They can be either positive or negative
575values. Default value for both is "0".
576
577@item shadowcolor
578The color to be used for drawing a shadow behind the drawn text. It
579can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
580form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
581The default value of @var{shadowcolor} is "black".
582
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583@item ft_load_flags
584Flags to be used for loading the fonts.
585
586The flags map the corresponding flags supported by libfreetype, and are
587a combination of the following values:
588@table @var
589@item default
590@item no_scale
591@item no_hinting
592@item render
593@item no_bitmap
594@item vertical_layout
595@item force_autohint
596@item crop_bitmap
597@item pedantic
598@item ignore_global_advance_width
599@item no_recurse
600@item ignore_transform
601@item monochrome
602@item linear_design
603@item no_autohint
604@item end table
605@end table
606
607Default value is "render".
608
609For more information consult the documentation for the FT_LOAD_*
610libfreetype flags.
611
612@item tabsize
613The size in number of spaces to use for rendering the tab.
614Default value is 4.
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615
616@item fix_bounds
617If true, check and fix text coords to avoid clipping.
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618@end table
619
620For example the command:
621@example
622drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
623@end example
624
625will draw "Test Text" with font FreeSerif, using the default values
626for the optional parameters.
627
628The command:
629@example
630drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
631 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
632@end example
633
634will draw 'Test Text' with font FreeSerif of size 24 at position x=100
635and y=50 (counting from the top-left corner of the screen), text is
636yellow with a red box around it. Both the text and the box have an
637opacity of 20%.
638
639Note that the double quotes are not necessary if spaces are not used
640within the parameter list.
641
642For more information about libfreetype, check:
643@url{http://www.freetype.org/}.
644
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645@section fade
646
647Apply fade-in/out effect to input video.
648
649It accepts the parameters:
650@var{type}:@var{start_frame}:@var{nb_frames}
651
652@var{type} specifies if the effect type, can be either "in" for
653fade-in, or "out" for a fade-out effect.
654
655@var{start_frame} specifies the number of the start frame for starting
656to apply the fade effect.
657
658@var{nb_frames} specifies the number of frames for which the fade
659effect has to last. At the end of the fade-in effect the output video
660will have the same intensity as the input video, at the end of the
661fade-out transition the output video will be completely black.
662
663A few usage examples follow, usable too as test scenarios.
664@example
665# fade in first 30 frames of video
666fade=in:0:30
667
668# fade out last 45 frames of a 200-frame video
669fade=out:155:45
670
671# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
672fade=in:0:25, fade=out:975:25
673
674# make first 5 frames black, then fade in from frame 5-24
675fade=in:5:20
676@end example
677
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678@section fieldorder
679
680Transform the field order of the input video.
681
682It accepts one parameter which specifies the required field order that
683the input interlaced video will be transformed to. The parameter can
684assume one of the following values:
685
686@table @option
687@item 0 or bff
688output bottom field first
689@item 1 or tff
690output top field first
691@end table
692
693Default value is "tff".
694
695Transformation is achieved by shifting the picture content up or down
696by one line, and filling the remaining line with appropriate picture content.
697This method is consistent with most broadcast field order converters.
698
699If the input video is not flagged as being interlaced, or it is already
700flagged as being of the required output field order then this filter does
701not alter the incoming video.
702
703This filter is very useful when converting to or from PAL DV material,
704which is bottom field first.
705
706For example:
707@example
9270b8a3 708./avconv -i in.vob -vf "fieldorder=bff" out.dv
2f84bb42
MH
709@end example
710
7f1af825
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711@section fifo
712
713Buffer input images and send them when they are requested.
714
715This filter is mainly useful when auto-inserted by the libavfilter
716framework.
717
718The filter does not take parameters.
719
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720@section format
721
722Convert the input video to one of the specified pixel formats.
723Libavfilter will try to pick one that is supported for the input to
724the next filter.
725
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726The filter accepts a list of pixel format names, separated by ":",
727for example "yuv420p:monow:rgb24".
3275ac6a 728
f150e4dc 729Some examples follow:
3275ac6a 730@example
f150e4dc
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731# convert the input video to the format "yuv420p"
732format=yuv420p
3275ac6a 733
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734# convert the input video to any of the formats in the list
735format=yuv420p:yuv444p:yuv410p
736@end example
3275ac6a 737
f8608dca 738@anchor{frei0r}
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739@section frei0r
740
741Apply a frei0r effect to the input video.
742
743To enable compilation of this filter you need to install the frei0r
f8a45fa1 744header and configure Libav with --enable-frei0r.
47941088
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745
746The filter supports the syntax:
747@example
f51aeedd 748@var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
47941088
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749@end example
750
751@var{filter_name} is the name to the frei0r effect to load. If the
752environment variable @env{FREI0R_PATH} is defined, the frei0r effect
753is searched in each one of the directories specified by the colon
754separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
755paths, which are in this order: @file{HOME/.frei0r-1/lib/},
756@file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
757
758@var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
759for the frei0r effect.
760
761A frei0r effect parameter can be a boolean (whose values are specified
762with "y" and "n"), a double, a color (specified by the syntax
763@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
764numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
765description), a position (specified by the syntax @var{X}/@var{Y},
766@var{X} and @var{Y} being float numbers) and a string.
767
768The number and kind of parameters depend on the loaded effect. If an
769effect parameter is not specified the default value is set.
770
771Some examples follow:
772@example
773# apply the distort0r effect, set the first two double parameters
774frei0r=distort0r:0.5:0.01
775
776# apply the colordistance effect, takes a color as first parameter
777frei0r=colordistance:0.2/0.3/0.4
778frei0r=colordistance:violet
779frei0r=colordistance:0x112233
780
781# apply the perspective effect, specify the top left and top right
782# image positions
783frei0r=perspective:0.2/0.2:0.8/0.2
784@end example
785
786For more information see:
787@url{http://piksel.org/frei0r}
788
d5f187fd
N
789@section gradfun
790
791Fix the banding artifacts that are sometimes introduced into nearly flat
792regions by truncation to 8bit colordepth.
793Interpolate the gradients that should go where the bands are, and
794dither them.
795
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796This filter is designed for playback only. Do not use it prior to
797lossy compression, because compression tends to lose the dither and
798bring back the bands.
799
d5f187fd
N
800The filter takes two optional parameters, separated by ':':
801@var{strength}:@var{radius}
802
803@var{strength} is the maximum amount by which the filter will change
804any one pixel. Also the threshold for detecting nearly flat
805regions. Acceptable values range from .51 to 255, default value is
8061.2, out-of-range values will be clipped to the valid range.
807
808@var{radius} is the neighborhood to fit the gradient to. A larger
809radius makes for smoother gradients, but also prevents the filter from
810modifying the pixels near detailed regions. Acceptable values are
8118-32, default value is 16, out-of-range values will be clipped to the
812valid range.
813
814@example
815# default parameters
816gradfun=1.2:16
817
818# omitting radius
819gradfun=1.2
820@end example
821
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822@section hflip
823
824Flip the input video horizontally.
825
9270b8a3 826For example to horizontally flip the input video with @command{avconv}:
a1e171df 827@example
9270b8a3 828avconv -i in.avi -vf "hflip" out.avi
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829@end example
830
a4dc7aa5
BC
831@section hqdn3d
832
833High precision/quality 3d denoise filter. This filter aims to reduce
834image noise producing smooth images and making still images really
835still. It should enhance compressibility.
836
837It accepts the following optional parameters:
838@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
839
840@table @option
841@item luma_spatial
842a non-negative float number which specifies spatial luma strength,
843defaults to 4.0
844
845@item chroma_spatial
846a non-negative float number which specifies spatial chroma strength,
847defaults to 3.0*@var{luma_spatial}/4.0
848
849@item luma_tmp
850a float number which specifies luma temporal strength, defaults to
8516.0*@var{luma_spatial}/4.0
852
853@item chroma_tmp
854a float number which specifies chroma temporal strength, defaults to
855@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
856@end table
857
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858@section lut, lutrgb, lutyuv
859
860Compute a look-up table for binding each pixel component input value
861to an output value, and apply it to input video.
862
863@var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
864to an RGB input video.
865
866These filters accept in input a ":"-separated list of options, which
867specify the expressions used for computing the lookup table for the
868corresponding pixel component values.
869
870The @var{lut} filter requires either YUV or RGB pixel formats in
871input, and accepts the options:
872@table @option
873@var{c0} (first pixel component)
874@var{c1} (second pixel component)
875@var{c2} (third pixel component)
876@var{c3} (fourth pixel component, corresponds to the alpha component)
877@end table
878
879The exact component associated to each option depends on the format in
880input.
881
882The @var{lutrgb} filter requires RGB pixel formats in input, and
883accepts the options:
884@table @option
885@var{r} (red component)
886@var{g} (green component)
887@var{b} (blue component)
888@var{a} (alpha component)
889@end table
890
891The @var{lutyuv} filter requires YUV pixel formats in input, and
892accepts the options:
893@table @option
894@var{y} (Y/luminance component)
895@var{u} (U/Cb component)
896@var{v} (V/Cr component)
897@var{a} (alpha component)
898@end table
899
900The expressions can contain the following constants and functions:
901
902@table @option
903@item E, PI, PHI
904the corresponding mathematical approximated values for e
905(euler number), pi (greek PI), PHI (golden ratio)
906
907@item w, h
da9cea77 908the input width and height
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SS
909
910@item val
911input value for the pixel component
912
913@item clipval
914the input value clipped in the @var{minval}-@var{maxval} range
915
916@item maxval
917maximum value for the pixel component
918
919@item minval
920minimum value for the pixel component
921
922@item negval
923the negated value for the pixel component value clipped in the
924@var{minval}-@var{maxval} range , it corresponds to the expression
925"maxval-clipval+minval"
926
927@item clip(val)
928the computed value in @var{val} clipped in the
929@var{minval}-@var{maxval} range
930
931@item gammaval(gamma)
932the computed gamma correction value of the pixel component value
933clipped in the @var{minval}-@var{maxval} range, corresponds to the
934expression
935"pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
936
937@end table
938
939All expressions default to "val".
940
941Some examples follow:
942@example
943# negate input video
944lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
945lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
946
947# the above is the same as
948lutrgb="r=negval:g=negval:b=negval"
949lutyuv="y=negval:u=negval:v=negval"
950
951# negate luminance
952lutyuv=negval
953
954# remove chroma components, turns the video into a graytone image
955lutyuv="u=128:v=128"
956
957# apply a luma burning effect
958lutyuv="y=2*val"
959
960# remove green and blue components
961lutrgb="g=0:b=0"
962
963# set a constant alpha channel value on input
964format=rgba,lutrgb=a="maxval-minval/2"
965
966# correct luminance gamma by a 0.5 factor
967lutyuv=y=gammaval(0.5)
968@end example
969
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SS
970@section negate
971
972Negate input video.
973
974This filter accepts an integer in input, if non-zero it negates the
975alpha component (if available). The default value in input is 0.
3275ac6a
SS
976
977Force libavfilter not to use any of the specified pixel formats for the
978input to the next filter.
979
b1094275
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980The filter accepts a list of pixel format names, separated by ":",
981for example "yuv420p:monow:rgb24".
3275ac6a 982
f150e4dc 983Some examples follow:
3275ac6a 984@example
f150e4dc
SS
985# force libavfilter to use a format different from "yuv420p" for the
986# input to the vflip filter
987noformat=yuv420p,vflip
3275ac6a 988
f150e4dc
SS
989# convert the input video to any of the formats not contained in the list
990noformat=yuv420p:yuv444p:yuv410p
991@end example
3275ac6a
SS
992
993@section null
994
99046339 995Pass the video source unchanged to the output.
3275ac6a 996
cf69ad35 997@section ocv
6ebf0bfc 998
cf69ad35 999Apply video transform using libopencv.
6ebf0bfc
SS
1000
1001To enable this filter install libopencv library and headers and
f8a45fa1 1002configure Libav with --enable-libopencv.
6ebf0bfc 1003
cf69ad35
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1004The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1005
1006@var{filter_name} is the name of the libopencv filter to apply.
1007
1008@var{filter_params} specifies the parameters to pass to the libopencv
1009filter. If not specified the default values are assumed.
1010
1011Refer to the official libopencv documentation for more precise
da9cea77 1012information:
cf69ad35
SS
1013@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1014
1015Follows the list of supported libopencv filters.
1016
17fc9493 1017@anchor{dilate}
91cbb6ba
SS
1018@subsection dilate
1019
1020Dilate an image by using a specific structuring element.
1021This filter corresponds to the libopencv function @code{cvDilate}.
1022
1023It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1024
1025@var{struct_el} represents a structuring element, and has the syntax:
1026@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1027
da9cea77 1028@var{cols} and @var{rows} represent the number of columns and rows of
91cbb6ba
SS
1029the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1030point, and @var{shape} the shape for the structuring element, and
1031can be one of the values "rect", "cross", "ellipse", "custom".
1032
1033If the value for @var{shape} is "custom", it must be followed by a
1034string of the form "=@var{filename}". The file with name
1035@var{filename} is assumed to represent a binary image, with each
1036printable character corresponding to a bright pixel. When a custom
1037@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1038or columns and rows of the read file are assumed instead.
1039
1040The default value for @var{struct_el} is "3x3+0x0/rect".
1041
1042@var{nb_iterations} specifies the number of times the transform is
1043applied to the image, and defaults to 1.
1044
1045Follow some example:
1046@example
1047# use the default values
1048ocv=dilate
1049
1050# dilate using a structuring element with a 5x5 cross, iterate two times
1051ocv=dilate=5x5+2x2/cross:2
1052
1053# read the shape from the file diamond.shape, iterate two times
1054# the file diamond.shape may contain a pattern of characters like this:
1055# *
1056# ***
1057# *****
1058# ***
1059# *
1060# the specified cols and rows are ignored (but not the anchor point coordinates)
1061ocv=0x0+2x2/custom=diamond.shape:2
1062@end example
1063
17fc9493
SS
1064@subsection erode
1065
1066Erode an image by using a specific structuring element.
1067This filter corresponds to the libopencv function @code{cvErode}.
1068
1069The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
4c989761 1070with the same syntax and semantics as the @ref{dilate} filter.
17fc9493 1071
cf69ad35
SS
1072@subsection smooth
1073
1074Smooth the input video.
1075
1076The filter takes the following parameters:
6ebf0bfc
SS
1077@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1078
1079@var{type} is the type of smooth filter to apply, and can be one of
58d94364 1080the following values: "blur", "blur_no_scale", "median", "gaussian",
6ebf0bfc
SS
1081"bilateral". The default value is "gaussian".
1082
1083@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1084parameters whose meanings depend on smooth type. @var{param1} and
1085@var{param2} accept integer positive values or 0, @var{param3} and
1086@var{param4} accept float values.
1087
1088The default value for @var{param1} is 3, the default value for the
1089other parameters is 0.
1090
58d94364 1091These parameters correspond to the parameters assigned to the
cf69ad35 1092libopencv function @code{cvSmooth}.
6ebf0bfc 1093
2cf74eca 1094@anchor{overlay}
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SS
1095@section overlay
1096
1097Overlay one video on top of another.
1098
1099It takes two inputs and one output, the first input is the "main"
1100video on which the second input is overlayed.
1101
1102It accepts the parameters: @var{x}:@var{y}.
1103
1104@var{x} is the x coordinate of the overlayed video on the main video,
1105@var{y} is the y coordinate. The parameters are expressions containing
1106the following parameters:
1107
1108@table @option
1109@item main_w, main_h
1110main input width and height
1111
1112@item W, H
1113same as @var{main_w} and @var{main_h}
1114
1115@item overlay_w, overlay_h
1116overlay input width and height
1117
1118@item w, h
1119same as @var{overlay_w} and @var{overlay_h}
1120@end table
1121
1122Be aware that frames are taken from each input video in timestamp
1123order, hence, if their initial timestamps differ, it is a a good idea
1124to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1125have them begin in the same zero timestamp, as it does the example for
1126the @var{movie} filter.
1127
1128Follow some examples:
1129@example
1130# draw the overlay at 10 pixels from the bottom right
1131# corner of the main video.
1132overlay=main_w-overlay_w-10:main_h-overlay_h-10
1133
1134# insert a transparent PNG logo in the bottom left corner of the input
7ce118ba 1135avconv -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
58935b25
SS
1136
1137# insert 2 different transparent PNG logos (second logo on bottom
1138# right corner):
7ce118ba
AK
1139avconv -i input -i logo1 -i logo2 -filter_complex
1140'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
58935b25
SS
1141
1142# add a transparent color layer on top of the main video,
1143# WxH specifies the size of the main input to the overlay filter
1144color=red@.3:WxH [over]; [in][over] overlay [out]
1145@end example
1146
b0641ab7 1147You can chain together more overlays but the efficiency of such
58935b25
SS
1148approach is yet to be tested.
1149
3275ac6a
SS
1150@section pad
1151
1152Add paddings to the input image, and places the original input at the
1153given coordinates @var{x}, @var{y}.
1154
1155It accepts the following parameters:
1156@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1157
73a4f7c2
SS
1158The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1159expressions containing the following constants:
1160
1161@table @option
1162@item E, PI, PHI
1163the corresponding mathematical approximated values for e
1164(euler number), pi (greek PI), phi (golden ratio)
1165
1166@item in_w, in_h
e83c2dde 1167the input video width and height
73a4f7c2
SS
1168
1169@item iw, ih
1170same as @var{in_w} and @var{in_h}
1171
1172@item out_w, out_h
e83c2dde 1173the output width and height, that is the size of the padded area as
73a4f7c2
SS
1174specified by the @var{width} and @var{height} expressions
1175
1176@item ow, oh
1177same as @var{out_w} and @var{out_h}
1178
1179@item x, y
1180x and y offsets as specified by the @var{x} and @var{y}
1181expressions, or NAN if not yet specified
1182
1183@item a
1184input display aspect ratio, same as @var{iw} / @var{ih}
1185
1186@item hsub, vsub
1187horizontal and vertical chroma subsample values. For example for the
1188pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1189@end table
1190
3275ac6a
SS
1191Follows the description of the accepted parameters.
1192
1193@table @option
1194@item width, height
1195
1196Specify the size of the output image with the paddings added. If the
1197value for @var{width} or @var{height} is 0, the corresponding input size
1198is used for the output.
1199
73a4f7c2 1200The @var{width} expression can reference the value set by the
da9cea77 1201@var{height} expression, and vice versa.
73a4f7c2 1202
3275ac6a
SS
1203The default value of @var{width} and @var{height} is 0.
1204
1205@item x, y
1206
1207Specify the offsets where to place the input image in the padded area
1208with respect to the top/left border of the output image.
1209
73a4f7c2 1210The @var{x} expression can reference the value set by the @var{y}
da9cea77 1211expression, and vice versa.
73a4f7c2 1212
3275ac6a
SS
1213The default value of @var{x} and @var{y} is 0.
1214
1215@item color
1216
1217Specify the color of the padded area, it can be the name of a color
1218(case insensitive match) or a 0xRRGGBB[AA] sequence.
1219
b1094275 1220The default value of @var{color} is "black".
3275ac6a
SS
1221
1222@end table
1223
73a4f7c2 1224Some examples follow:
3d17f4b9
SS
1225
1226@example
1227# Add paddings with color "violet" to the input video. Output video
1228# size is 640x480, the top-left corner of the input video is placed at
aeefbf61 1229# column 0, row 40.
3d17f4b9 1230pad=640:480:0:40:violet
73a4f7c2
SS
1231
1232# pad the input to get an output with dimensions increased bt 3/2,
1233# and put the input video at the center of the padded area
1234pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1235
1236# pad the input to get a squared output with size equal to the maximum
1237# value between the input width and height, and put the input video at
1238# the center of the padded area
1239pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1240
1241# pad the input to get a final w/h ratio of 16:9
1242pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1243
1244# double output size and put the input video in the bottom-right
1245# corner of the output padded area
1246pad="2*iw:2*ih:ow-iw:oh-ih"
3d17f4b9
SS
1247@end example
1248
ce2e4ae3
SS
1249@section pixdesctest
1250
1251Pixel format descriptor test filter, mainly useful for internal
1252testing. The output video should be equal to the input video.
1253
1254For example:
1255@example
1256format=monow, pixdesctest
1257@end example
1258
1259can be used to test the monowhite pixel format descriptor definition.
1260
3275ac6a
SS
1261@section scale
1262
1263Scale the input video to @var{width}:@var{height} and/or convert the image format.
1264
68e23c08
SS
1265The parameters @var{width} and @var{height} are expressions containing
1266the following constants:
3275ac6a 1267
68e23c08
SS
1268@table @option
1269@item E, PI, PHI
1270the corresponding mathematical approximated values for e
1271(euler number), pi (greek PI), phi (golden ratio)
1272
1273@item in_w, in_h
e83c2dde 1274the input width and height
68e23c08
SS
1275
1276@item iw, ih
1277same as @var{in_w} and @var{in_h}
1278
1279@item out_w, out_h
e83c2dde 1280the output (cropped) width and height
68e23c08
SS
1281
1282@item ow, oh
1283same as @var{out_w} and @var{out_h}
3275ac6a 1284
46b29397 1285@item dar, a
68e23c08
SS
1286input display aspect ratio, same as @var{iw} / @var{ih}
1287
46b29397
SS
1288@item sar
1289input sample aspect ratio
1290
68e23c08
SS
1291@item hsub, vsub
1292horizontal and vertical chroma subsample values. For example for the
1293pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1294@end table
3275ac6a
SS
1295
1296If the input image format is different from the format requested by
1297the next filter, the scale filter will convert the input to the
1298requested format.
1299
1300If the value for @var{width} or @var{height} is 0, the respective input
1301size is used for the output.
1302
1303If the value for @var{width} or @var{height} is -1, the scale filter will
1304use, for the respective output size, a value that maintains the aspect
1305ratio of the input image.
1306
1307The default value of @var{width} and @var{height} is 0.
1308
68e23c08
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1309Some examples follow:
1310@example
1311# scale the input video to a size of 200x100.
1312scale=200:100
1313
1314# scale the input to 2x
1315scale=2*iw:2*ih
1316# the above is the same as
1317scale=2*in_w:2*in_h
1318
1319# scale the input to half size
1320scale=iw/2:ih/2
1321
1322# increase the width, and set the height to the same size
1323scale=3/2*iw:ow
1324
1325# seek for Greek harmony
1326scale=iw:1/PHI*iw
1327scale=ih*PHI:ih
1328
1329# increase the height, and set the width to 3/2 of the height
1330scale=3/2*oh:3/5*ih
1331
1332# increase the size, but make the size a multiple of the chroma
1333scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1334
1335# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1336scale='min(500\, iw*3/2):-1'
1337@end example
1338
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1339@section select
1340Select frames to pass in output.
1341
1342It accepts in input an expression, which is evaluated for each input
1343frame. If the expression is evaluated to a non-zero value, the frame
1344is selected and passed to the output, otherwise it is discarded.
1345
1346The expression can contain the following constants:
1347
1348@table @option
1349@item PI
1350Greek PI
1351
1352@item PHI
1353golden ratio
1354
1355@item E
1356Euler number
1357
1358@item n
1359the sequential number of the filtered frame, starting from 0
1360
1361@item selected_n
1362the sequential number of the selected frame, starting from 0
1363
1364@item prev_selected_n
1365the sequential number of the last selected frame, NAN if undefined
1366
1367@item TB
1368timebase of the input timestamps
1369
1370@item pts
1371the PTS (Presentation TimeStamp) of the filtered video frame,
1372expressed in @var{TB} units, NAN if undefined
1373
1374@item t
1375the PTS (Presentation TimeStamp) of the filtered video frame,
1376expressed in seconds, NAN if undefined
1377
1378@item prev_pts
1379the PTS of the previously filtered video frame, NAN if undefined
1380
1381@item prev_selected_pts
1382the PTS of the last previously filtered video frame, NAN if undefined
1383
1384@item prev_selected_t
1385the PTS of the last previously selected video frame, NAN if undefined
1386
1387@item start_pts
1388the PTS of the first video frame in the video, NAN if undefined
1389
1390@item start_t
1391the time of the first video frame in the video, NAN if undefined
1392
1393@item pict_type
1394the type of the filtered frame, can assume one of the following
1395values:
1396@table @option
1397@item I
1398@item P
1399@item B
1400@item S
1401@item SI
1402@item SP
1403@item BI
1404@end table
1405
1406@item interlace_type
1407the frame interlace type, can assume one of the following values:
1408@table @option
1409@item PROGRESSIVE
1410the frame is progressive (not interlaced)
1411@item TOPFIRST
1412the frame is top-field-first
1413@item BOTTOMFIRST
1414the frame is bottom-field-first
1415@end table
1416
1417@item key
14181 if the filtered frame is a key-frame, 0 otherwise
1419
1420@item pos
1421the position in the file of the filtered frame, -1 if the information
1422is not available (e.g. for synthetic video)
1423@end table
1424
1425The default value of the select expression is "1".
1426
1427Some examples follow:
1428
1429@example
1430# select all frames in input
1431select
1432
1433# the above is the same as:
1434select=1
1435
1436# skip all frames:
1437select=0
1438
1439# select only I-frames
1440select='eq(pict_type\,I)'
1441
1442# select one frame every 100
1443select='not(mod(n\,100))'
1444
1445# select only frames contained in the 10-20 time interval
1446select='gte(t\,10)*lte(t\,20)'
1447
1448# select only I frames contained in the 10-20 time interval
1449select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
1450
1451# select frames with a minimum distance of 10 seconds
1452select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
1453@end example
1454
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1455@anchor{setdar}
1456@section setdar
1457
1458Set the Display Aspect Ratio for the filter output video.
1459
1460This is done by changing the specified Sample (aka Pixel) Aspect
1461Ratio, according to the following equation:
1462@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1463
1464Keep in mind that this filter does not modify the pixel dimensions of
1465the video frame. Also the display aspect ratio set by this filter may
1466be changed by later filters in the filterchain, e.g. in case of
1467scaling or if another "setdar" or a "setsar" filter is applied.
1468
1469The filter accepts a parameter string which represents the wanted
1470display aspect ratio.
1471The parameter can be a floating point number string, or an expression
1472of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1473numerator and denominator of the aspect ratio.
1474If the parameter is not specified, it is assumed the value "0:1".
1475
1476For example to change the display aspect ratio to 16:9, specify:
1477@example
1478setdar=16:9
1479# the above is equivalent to
1480setdar=1.77777
1481@end example
1482
4c989761 1483See also the @ref{setsar} filter documentation.
2fd8756b 1484
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1485@section setpts
1486
1487Change the PTS (presentation timestamp) of the input video frames.
1488
1489Accept in input an expression evaluated through the eval API, which
1490can contain the following constants:
1491
1492@table @option
1493@item PTS
1494the presentation timestamp in input
1495
1496@item PI
1497Greek PI
1498
1499@item PHI
1500golden ratio
1501
1502@item E
1503Euler number
1504
1505@item N
1506the count of the input frame, starting from 0.
1507
1508@item STARTPTS
1509the PTS of the first video frame
1510
1511@item INTERLACED
1512tell if the current frame is interlaced
1513
1514@item POS
1515original position in the file of the frame, or undefined if undefined
1516for the current frame
1517
1518@item PREV_INPTS
1519previous input PTS
1520
1521@item PREV_OUTPTS
1522previous output PTS
1523
1524@end table
1525
1526Some examples follow:
1527
1528@example
1529# start counting PTS from zero
1530setpts=PTS-STARTPTS
1531
1532# fast motion
1533setpts=0.5*PTS
1534
1535# slow motion
1536setpts=2.0*PTS
1537
1538# fixed rate 25 fps
1539setpts=N/(25*TB)
1540
1541# fixed rate 25 fps with some jitter
1542setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1543@end example
1544
2fd8756b
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1545@anchor{setsar}
1546@section setsar
1547
1548Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1549
1550Note that as a consequence of the application of this filter, the
1551output display aspect ratio will change according to the following
1552equation:
1553@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1554
1555Keep in mind that the sample aspect ratio set by this filter may be
1556changed by later filters in the filterchain, e.g. if another "setsar"
1557or a "setdar" filter is applied.
1558
1559The filter accepts a parameter string which represents the wanted
1560sample aspect ratio.
1561The parameter can be a floating point number string, or an expression
1562of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1563numerator and denominator of the aspect ratio.
1564If the parameter is not specified, it is assumed the value "0:1".
1565
1566For example to change the sample aspect ratio to 10:11, specify:
1567@example
1568setsar=10:11
1569@end example
1570
d89e3b36
SS
1571@section settb
1572
1573Set the timebase to use for the output frames timestamps.
1574It is mainly useful for testing timebase configuration.
1575
1576It accepts in input an arithmetic expression representing a rational.
1577The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1578default timebase), and "intb" (the input timebase).
1579
1580The default value for the input is "intb".
1581
1582Follow some examples.
1583
1584@example
1585# set the timebase to 1/25
1586settb=1/25
1587
1588# set the timebase to 1/10
1589settb=0.1
1590
1591#set the timebase to 1001/1000
1592settb=1+0.001
1593
1594#set the timebase to 2*intb
1595settb=2*intb
1596
1597#set the default timebase value
1598settb=AVTB
1599@end example
1600
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1601@section showinfo
1602
1603Show a line containing various information for each input video frame.
1604The input video is not modified.
1605
1606The shown line contains a sequence of key/value pairs of the form
1607@var{key}:@var{value}.
1608
1609A description of each shown parameter follows:
1610
1611@table @option
1612@item n
1613sequential number of the input frame, starting from 0
1614
1615@item pts
1616Presentation TimeStamp of the input frame, expressed as a number of
1617time base units. The time base unit depends on the filter input pad.
1618
1619@item pts_time
1620Presentation TimeStamp of the input frame, expressed as a number of
1621seconds
1622
1623@item pos
1624position of the frame in the input stream, -1 if this information in
da9cea77 1625unavailable and/or meaningless (for example in case of synthetic video)
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SS
1626
1627@item fmt
1628pixel format name
1629
1630@item sar
1631sample aspect ratio of the input frame, expressed in the form
1632@var{num}/@var{den}
1633
1634@item s
1635size of the input frame, expressed in the form
1636@var{width}x@var{height}
1637
1638@item i
1639interlaced mode ("P" for "progressive", "T" for top field first, "B"
1640for bottom field first)
1641
1642@item iskey
16431 if the frame is a key frame, 0 otherwise
1644
1645@item type
1646picture type of the input frame ("I" for an I-frame, "P" for a
1647P-frame, "B" for a B-frame, "?" for unknown type).
1648Check also the documentation of the @code{AVPictureType} enum and of
1649the @code{av_get_picture_type_char} function defined in
1650@file{libavutil/avutil.h}.
1651
1652@item checksum
1653Adler-32 checksum of all the planes of the input frame
1654
1655@item plane_checksum
1656Adler-32 checksum of each plane of the input frame, expressed in the form
1657"[@var{c0} @var{c1} @var{c2} @var{c3}]"
1658@end table
1659
3275ac6a
SS
1660@section slicify
1661
1662Pass the images of input video on to next video filter as multiple
1663slices.
1664
1665@example
9270b8a3 1666./avconv -i in.avi -vf "slicify=32" out.avi
3275ac6a
SS
1667@end example
1668
1669The filter accepts the slice height as parameter. If the parameter is
1670not specified it will use the default value of 16.
1671
1672Adding this in the beginning of filter chains should make filtering
1673faster due to better use of the memory cache.
1674
fd18ee0f
AK
1675@section split
1676
1677Split input video into several identical outputs.
1678
1679The filter accepts a single parameter which specifies the number of outputs. If
1680unspecified, it defaults to 2.
1681
1682For example
1683@example
1684avconv -i INPUT -filter_complex split=5 OUTPUT
1685@end example
1686will create 5 copies of the input video.
1687
43945b27
SS
1688@section transpose
1689
1690Transpose rows with columns in the input video and optionally flip it.
1691
1692It accepts a parameter representing an integer, which can assume the
1693values:
1694
1695@table @samp
1696@item 0
1697Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1698@example
1699L.R L.l
1700. . -> . .
1701l.r R.r
1702@end example
1703
1704@item 1
1705Rotate by 90 degrees clockwise, that is:
1706@example
1707L.R l.L
1708. . -> . .
1709l.r r.R
1710@end example
1711
1712@item 2
1713Rotate by 90 degrees counterclockwise, that is:
1714@example
1715L.R R.r
1716. . -> . .
1717l.r L.l
1718@end example
1719
1720@item 3
1721Rotate by 90 degrees clockwise and vertically flip, that is:
1722@example
1723L.R r.R
1724. . -> . .
1725l.r l.L
1726@end example
1727@end table
1728
3275ac6a
SS
1729@section unsharp
1730
843b5fd0
SS
1731Sharpen or blur the input video.
1732
1733It accepts the following parameters:
1734@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
3275ac6a
SS
1735
1736Negative values for the amount will blur the input video, while positive
1737values will sharpen. All parameters are optional and default to the
1ee20141 1738equivalent of the string '5:5:1.0:5:5:0.0'.
3275ac6a
SS
1739
1740@table @option
1741
1742@item luma_msize_x
1743Set the luma matrix horizontal size. It can be an integer between 3
1744and 13, default value is 5.
1745
1746@item luma_msize_y
1747Set the luma matrix vertical size. It can be an integer between 3
1748and 13, default value is 5.
1749
1750@item luma_amount
1751Set the luma effect strength. It can be a float number between -2.0
1752and 5.0, default value is 1.0.
1753
1754@item chroma_msize_x
1755Set the chroma matrix horizontal size. It can be an integer between 3
1ee20141 1756and 13, default value is 5.
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SS
1757
1758@item chroma_msize_y
1759Set the chroma matrix vertical size. It can be an integer between 3
1ee20141 1760and 13, default value is 5.
3275ac6a
SS
1761
1762@item luma_amount
1763Set the chroma effect strength. It can be a float number between -2.0
1764and 5.0, default value is 0.0.
1765
1766@end table
1767
1768@example
1769# Strong luma sharpen effect parameters
1770unsharp=7:7:2.5
1771
1772# Strong blur of both luma and chroma parameters
1773unsharp=7:7:-2:7:7:-2
1774
9270b8a3
LB
1775# Use the default values with @command{avconv}
1776./avconv -i in.avi -vf "unsharp" out.mp4
3275ac6a
SS
1777@end example
1778
1779@section vflip
1780
1781Flip the input video vertically.
1782
1783@example
9270b8a3 1784./avconv -i in.avi -vf "vflip" out.avi
3275ac6a
SS
1785@end example
1786
acbac567
MN
1787@section yadif
1788
1653027a
SS
1789Deinterlace the input video ("yadif" means "yet another deinterlacing
1790filter").
acbac567 1791
ab09df9d 1792It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
acbac567 1793
1653027a
SS
1794@var{mode} specifies the interlacing mode to adopt, accepts one of the
1795following values:
acbac567 1796
1653027a
SS
1797@table @option
1798@item 0
1799output 1 frame for each frame
1800@item 1
1801output 1 frame for each field
1802@item 2
1803like 0 but skips spatial interlacing check
1804@item 3
1805like 1 but skips spatial interlacing check
1806@end table
acbac567
MN
1807
1808Default value is 0.
1809
1653027a
SS
1810@var{parity} specifies the picture field parity assumed for the input
1811interlaced video, accepts one of the following values:
acbac567 1812
1653027a
SS
1813@table @option
1814@item 0
1653027a 1815assume top field first
4703a7b5
SS
1816@item 1
1817assume bottom field first
1653027a
SS
1818@item -1
1819enable automatic detection
acbac567
MN
1820@end table
1821
1653027a 1822Default value is -1.
a51c71bb
BC
1823If interlacing is unknown or decoder does not export this information,
1824top field first will be assumed.
1653027a 1825
b0641ab7 1826@var{auto} specifies if deinterlacer should trust the interlaced flag
ab09df9d
JP
1827and only deinterlace frames marked as interlaced
1828
1829@table @option
1830@item 0
1831deinterlace all frames
1832@item 1
1833only deinterlace frames marked as interlaced
1834@end table
1835
1836Default value is 0.
1837
3275ac6a
SS
1838@c man end VIDEO FILTERS
1839
1840@chapter Video Sources
1841@c man begin VIDEO SOURCES
1842
1843Below is a description of the currently available video sources.
1844
24413399
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1845@section buffer
1846
1847Buffer video frames, and make them available to the filter chain.
1848
1849This source is mainly intended for a programmatic use, in particular
ac1a31ab 1850through the interface defined in @file{libavfilter/vsrc_buffer.h}.
24413399
SS
1851
1852It accepts the following parameters:
7a11c82f 1853@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 1854
da9cea77 1855All the parameters need to be explicitly defined.
24413399
SS
1856
1857Follows the list of the accepted parameters.
1858
1859@table @option
1860
1861@item width, height
1862Specify the width and height of the buffered video frames.
1863
1864@item pix_fmt_string
24413399
SS
1865A string representing the pixel format of the buffered video frames.
1866It may be a number corresponding to a pixel format, or a pixel format
1867name.
1868
94498ec9
SS
1869@item timebase_num, timebase_den
1870Specify numerator and denomitor of the timebase assumed by the
1871timestamps of the buffered frames.
7a11c82f
MN
1872
1873@item sample_aspect_ratio.num, sample_aspect_ratio.den
1874Specify numerator and denominator of the sample aspect ratio assumed
1875by the video frames.
24413399
SS
1876@end table
1877
1878For example:
1879@example
7a11c82f 1880buffer=320:240:yuv410p:1:24:1:1
24413399
SS
1881@end example
1882
1883will instruct the source to accept video frames with size 320x240 and
7a11c82f
MN
1884with format "yuv410p", assuming 1/24 as the timestamps timebase and
1885square pixels (1:1 sample aspect ratio).
94498ec9
SS
1886Since the pixel format with name "yuv410p" corresponds to the number 6
1887(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1888this example corresponds to:
24413399 1889@example
94498ec9 1890buffer=320:240:6:1:24
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SS
1891@end example
1892
23ccf3c7
SS
1893@section color
1894
1895Provide an uniformly colored input.
1896
1897It accepts the following parameters:
b5f47309 1898@var{color}:@var{frame_size}:@var{frame_rate}
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SS
1899
1900Follows the description of the accepted parameters.
1901
1902@table @option
1903
1904@item color
1905Specify the color of the source. It can be the name of a color (case
1906insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1907alpha specifier. The default value is "black".
1908
1909@item frame_size
1910Specify the size of the sourced video, it may be a string of the form
e83c2dde 1911@var{width}x@var{height}, or the name of a size abbreviation. The
23ccf3c7
SS
1912default value is "320x240".
1913
1914@item frame_rate
1915Specify the frame rate of the sourced video, as the number of frames
1916generated per second. It has to be a string in the format
1917@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1918number or a valid video frame rate abbreviation. The default value is
1919"25".
1920
1921@end table
1922
1923For example the following graph description will generate a red source
1924with an opacity of 0.2, with size "qcif" and a frame rate of 10
1925frames per second, which will be overlayed over the source connected
1926to the pad with identifier "in".
1927
1928@example
1929"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1930@end example
1931
9409c381
SS
1932@section movie
1933
1934Read a video stream from a movie container.
1935
1936It accepts the syntax: @var{movie_name}[:@var{options}] where
1937@var{movie_name} is the name of the resource to read (not necessarily
1938a file but also a device or a stream accessed through some protocol),
1939and @var{options} is an optional sequence of @var{key}=@var{value}
1940pairs, separated by ":".
1941
1942The description of the accepted options follows.
1943
1944@table @option
1945
1946@item format_name, f
1947Specifies the format assumed for the movie to read, and can be either
1948the name of a container or an input device. If not specified the
1949format is guessed from @var{movie_name} or by probing.
1950
1951@item seek_point, sp
1952Specifies the seek point in seconds, the frames will be output
1953starting from this seek point, the parameter is evaluated with
1954@code{av_strtod} so the numerical value may be suffixed by an IS
1955postfix. Default value is "0".
1956
1957@item stream_index, si
1958Specifies the index of the video stream to read. If the value is -1,
1959the best suited video stream will be automatically selected. Default
1960value is "-1".
1961
1962@end table
1963
1964This filter allows to overlay a second video on top of main input of
1965a filtergraph as shown in this graph:
1966@example
1967input -----------> deltapts0 --> overlay --> output
1968 ^
1969 |
1970movie --> scale--> deltapts1 -------+
1971@end example
1972
1973Some examples follow:
1974@example
1975# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1976# on top of the input labelled as "in".
1977movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1978[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1979
1980# read from a video4linux2 device, and overlay it on top of the input
1981# labelled as "in"
1982movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1983[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1984
1985@end example
1986
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1987@section nullsrc
1988
1989Null video source, never return images. It is mainly useful as a
1990template and to be employed in analysis / debugging tools.
1991
1992It accepts as optional parameter a string of the form
16134b7c 1993@var{width}:@var{height}:@var{timebase}.
3275ac6a 1994
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SS
1995@var{width} and @var{height} specify the size of the configured
1996source. The default values of @var{width} and @var{height} are
1997respectively 352 and 288 (corresponding to the CIF size format).
1998
1999@var{timebase} specifies an arithmetic expression representing a
2000timebase. The expression can contain the constants "PI", "E", "PHI",
2001"AVTB" (the default timebase), and defaults to the value "AVTB".
3275ac6a 2002
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2003@section frei0r_src
2004
2005Provide a frei0r source.
2006
2007To enable compilation of this filter you need to install the frei0r
f8a45fa1 2008header and configure Libav with --enable-frei0r.
f8608dca
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2009
2010The source supports the syntax:
2011@example
2012@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
2013@end example
2014
2015@var{size} is the size of the video to generate, may be a string of the
2016form @var{width}x@var{height} or a frame size abbreviation.
2017@var{rate} is the rate of the video to generate, may be a string of
2018the form @var{num}/@var{den} or a frame rate abbreviation.
2019@var{src_name} is the name to the frei0r source to load. For more
2020information regarding frei0r and how to set the parameters read the
4c989761 2021section @ref{frei0r} in the description of the video filters.
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2022
2023Some examples follow:
2024@example
2025# generate a frei0r partik0l source with size 200x200 and framerate 10
2026# which is overlayed on the overlay filter main input
2027frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
2028@end example
2029
ec2ac927 2030@section rgbtestsrc, testsrc
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2032The @code{rgbtestsrc} source generates an RGB test pattern useful for
2033detecting RGB vs BGR issues. You should see a red, green and blue
2034stripe from top to bottom.
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2036The @code{testsrc} source generates a test video pattern, showing a
2037color pattern, a scrolling gradient and a timestamp. This is mainly
2038intended for testing purposes.
2039
2040Both sources accept an optional sequence of @var{key}=@var{value} pairs,
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2041separated by ":". The description of the accepted options follows.
2042
2043@table @option
2044
2045@item size, s
2046Specify the size of the sourced video, it may be a string of the form
da9cea77 2047@var{width}x@var{height}, or the name of a size abbreviation. The
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2048default value is "320x240".
2049
2050@item rate, r
2051Specify the frame rate of the sourced video, as the number of frames
2052generated per second. It has to be a string in the format
2053@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2054number or a valid video frame rate abbreviation. The default value is
2055"25".
2056
2057@item sar
2058Set the sample aspect ratio of the sourced video.
2059
2060@item duration
2061Set the video duration of the sourced video. The accepted syntax is:
2062@example
2063[-]HH[:MM[:SS[.m...]]]
2064[-]S+[.m...]
2065@end example
2066See also the function @code{av_parse_time()}.
2067
2068If not specified, or the expressed duration is negative, the video is
2069supposed to be generated forever.
2070@end table
2071
2072For example the following:
2073@example
2074testsrc=duration=5.3:size=qcif:rate=10
2075@end example
2076
2077will generate a video with a duration of 5.3 seconds, with size
2078176x144 and a framerate of 10 frames per second.
2079
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2080@c man end VIDEO SOURCES
2081
2082@chapter Video Sinks
2083@c man begin VIDEO SINKS
2084
2085Below is a description of the currently available video sinks.
2086
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2087@section buffersink
2088
2089Buffer video frames, and make them available to the end of the filter
2090graph.
2091
2092This sink is intended for a programmatic use through the interface defined in
2093@file{libavfilter/buffersink.h}.
2094
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2095@section nullsink
2096
2097Null video sink, do absolutely nothing with the input video. It is
2098mainly useful as a template and to be employed in analysis / debugging
2099tools.
2100
2101@c man end VIDEO SINKS