Statistics
| Branch: | Revision:

ffmpeg / doc / filters.texi @ 2ccbb342

History | View | Annotate | Download (42.4 KB)

1
@chapter Filtergraph description
2
@c man begin FILTERGRAPH DESCRIPTION
3

    
4
A filtergraph is a directed graph of connected filters. It can contain
5
cycles, and there can be multiple links between a pair of
6
filters. Each link has one input pad on one side connecting it to one
7
filter from which it takes its input, and one output pad on the other
8
side connecting it to the one filter accepting its output.
9

    
10
Each filter in a filtergraph is an instance of a filter class
11
registered in the application, which defines the features and the
12
number of input and output pads of the filter.
13

    
14
A filter with no input pads is called a "source", a filter with no
15
output pads is called a "sink".
16

    
17
@section Filtergraph syntax
18

    
19
A filtergraph can be represented using a textual representation, which
20
is recognized by the @code{-vf} and @code{-af} options of the ff*
21
tools, and by the @code{av_parse_graph()} function defined in
22
@file{libavfilter/avfiltergraph}.
23

    
24
A filterchain consists of a sequence of connected filters, each one
25
connected to the previous one in the sequence. A filterchain is
26
represented by a list of ","-separated filter descriptions.
27

    
28
A filtergraph consists of a sequence of filterchains. A sequence of
29
filterchains is represented by a list of ";"-separated filterchain
30
descriptions.
31

    
32
A 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
36
described filter is an instance of, and has to be the name of one of
37
the filter classes registered in the program.
38
The 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
42
initialize the filter instance, and are described in the filter
43
descriptions below.
44

    
45
The list of arguments can be quoted using the character "'" as initial
46
and ending mark, and the character '\' for escaping the characters
47
within the quoted text; otherwise the argument string is considered
48
terminated when the next special character (belonging to the set
49
"[]=;,") is encountered.
50

    
51
The name and arguments of the filter are optionally preceded and
52
followed by a list of link labels.
53
A link label allows to name a link and associate it to a filter output
54
or input pad. The preceding labels @var{in_link_1}
55
... @var{in_link_N}, are associated to the filter input pads,
56
the following labels @var{out_link_1} ... @var{out_link_M}, are
57
associated to the output pads.
58

    
59
When two link labels with the same name are found in the
60
filtergraph, a link between the corresponding input and output pad is
61
created.
62

    
63
If an output pad is not labelled, it is linked by default to the first
64
unlabelled input pad of the next filter in the filterchain.
65
For example in the filterchain:
66
@example
67
nullsrc, split[L1], [L2]overlay, nullsink
68
@end example
69
the split filter instance has two output pads, and the overlay filter
70
instance 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
72
output pad of split is linked to the second input pad of overlay,
73
which are both unlabelled.
74

    
75
In a complete filterchain all the unlabelled filter input and output
76
pads must be connected. A filtergraph is considered valid if all the
77
filter input and output pads of all the filterchains are connected.
78

    
79
Follows 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

    
92
@chapter Audio Filters
93
@c man begin AUDIO FILTERS
94

    
95
When you configure your FFmpeg build, you can disable any of the
96
existing filters using --disable-filters.
97
The configure output will show the audio filters included in your
98
build.
99

    
100
Below is a description of the currently available audio filters.
101

    
102
@section anull
103

    
104
Pass the audio source unchanged to the output.
105

    
106
@c man end AUDIO FILTERS
107

    
108
@chapter Audio Sources
109
@c man begin AUDIO SOURCES
110

    
111
Below is a description of the currently available audio sources.
112

    
113
@section anullsrc
114

    
115
Null audio source, never return audio frames. It is mainly useful as a
116
template and to be employed in analysis / debugging tools.
117

    
118
It 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
124
integer or a string representing a channel layout. The default value
125
of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
126

    
127
Check the channel_layout_map definition in
128
@file{libavcodec/audioconvert.c} for the mapping between strings and
129
channel layout values.
130

    
131
Follow some examples:
132
@example
133
#  set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
134
anullsrc=48000:4
135

    
136
# same as
137
anullsrc=48000:mono
138
@end example
139

    
140
@c man end AUDIO SOURCES
141

    
142
@chapter Audio Sinks
143
@c man begin AUDIO SINKS
144

    
145
Below is a description of the currently available audio sinks.
146

    
147
@section anullsink
148

    
149
Null audio sink, do absolutely nothing with the input audio. It is
150
mainly useful as a template and to be employed in analysis / debugging
151
tools.
152

    
153
@c man end AUDIO SINKS
154

    
155
@chapter Video Filters
156
@c man begin VIDEO FILTERS
157

    
158
When you configure your FFmpeg build, you can disable any of the
159
existing filters using --disable-filters.
160
The configure output will show the video filters included in your
161
build.
162

    
163
Below is a description of the currently available video filters.
164

    
165
@section blackframe
166

    
167
Detect frames that are (almost) completely black. Can be useful to
168
detect chapter transitions or commercials. Output lines consist of
169
the frame number of the detected frame, the percentage of blackness,
170
the position in the file if known or -1 and the timestamp in seconds.
171

    
172
In order to display the output lines, you need to set the loglevel at
173
least to the AV_LOG_INFO value.
174

    
175
The filter accepts the syntax:
176
@example
177
blackframe[=@var{amount}:[@var{threshold}]]
178
@end example
179

    
180
@var{amount} is the percentage of the pixels that have to be below the
181
threshold, and defaults to 98.
182

    
183
@var{threshold} is the threshold below which a pixel value is
184
considered black, and defaults to 32.
185

    
186
@section copy
187

    
188
Copy the input source unchanged to the output. Mainly useful for
189
testing purposes.
190

    
191
@section crop
192

    
193
Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
194

    
195
The parameters are expressions containing the following constants:
196

    
197
@table @option
198
@item E, PI, PHI
199
the corresponding mathematical approximated values for e
200
(euler number), pi (greek PI), PHI (golden ratio)
201

    
202
@item x, y
203
the computed values for @var{x} and @var{y}. They are evaluated for
204
each new frame.
205

    
206
@item in_w, in_h
207
the input width and heigth
208

    
209
@item iw, ih
210
same as @var{in_w} and @var{in_h}
211

    
212
@item out_w, out_h
213
the output (cropped) width and heigth
214

    
215
@item ow, oh
216
same as @var{out_w} and @var{out_h}
217

    
218
@item n
219
the number of input frame, starting from 0
220

    
221
@item pos
222
the position in the file of the input frame, NAN if unknown
223

    
224
@item t
225
timestamp expressed in seconds, NAN if the input timestamp is unknown
226

    
227
@end table
228

    
229
The @var{out_w} and @var{out_h} parameters specify the expressions for
230
the width and height of the output (cropped) video. They are
231
evaluated just at the configuration of the filter.
232

    
233
The default value of @var{out_w} is "in_w", and the default value of
234
@var{out_h} is "in_h".
235

    
236
The expression for @var{out_w} may depend on the value of @var{out_h},
237
and the expression for @var{out_h} may depend on @var{out_w}, but they
238
cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
239
evaluated after @var{out_w} and @var{out_h}.
240

    
241
The @var{x} and @var{y} parameters specify the expressions for the
242
position of the top-left corner of the output (non-cropped) area. They
243
are evaluated for each frame. If the evaluated value is not valid, it
244
is approximated to the nearest valid value.
245

    
246
The default value of @var{x} is "(in_w-out_w)/2", and the default
247
value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
248
the center of the input image.
249

    
250
The expression for @var{x} may depend on @var{y}, and the expression
251
for @var{y} may depend on @var{x}.
252

    
253
Follow some examples:
254
@example
255
# crop the central input area with size 100x100
256
crop=100:100
257

    
258
# crop the central input area with size 2/3 of the input video
259
"crop=2/3*in_w:2/3*in_h"
260

    
261
# crop the input video central square
262
crop=in_h
263

    
264
# delimit the rectangle with the top-left corner placed at position
265
# 100:100 and the right-bottom corner corresponding to the right-bottom
266
# corner of the input image.
267
crop=in_w-100:in_h-100:100:100
268

    
269
# crop 10 pixels from the left and right borders, and 20 pixels from
270
# the top and bottom borders
271
"crop=in_w-2*10:in_h-2*20"
272

    
273
# keep only the bottom right quarter of the input image
274
"crop=in_w/2:in_h/2:in_w/2:in_h/2"
275

    
276
# crop height for getting Greek harmony
277
"crop=in_w:1/PHI*in_w"
278

    
279
# trembling effect
280
"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)"
281

    
282
# erratic camera effect depending on timestamp
283
"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)"
284

    
285
# set x depending on the value of y
286
"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
287
@end example
288

    
289
@section cropdetect
290

    
291
Auto-detect crop size.
292

    
293
Calculate necessary cropping parameters and prints the recommended
294
parameters through the logging system. The detected dimensions
295
correspond to the non-black area of the input video.
296

    
297
It accepts the syntax:
298
@example
299
cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
300
@end example
301

    
302
@table @option
303

    
304
@item limit
305
Threshold, which can be optionally specified from nothing (0) to
306
everything (255), defaults to 24.
307

    
308
@item round
309
Value which the width/height should be divisible by, defaults to
310
16. The offset is automatically adjusted to center the video. Use 2 to
311
get only even dimensions (needed for 4:2:2 video). 16 is best when
312
encoding to most video codecs.
313

    
314
@item reset
315
Counter that determines after how many frames cropdetect will reset
316
the previously detected largest video area and start over to detect
317
the current optimal crop area. Defaults to 0.
318

    
319
This can be useful when channel logos distort the video area. 0
320
indicates never reset and return the largest area encountered during
321
playback.
322
@end table
323

    
324
@section drawbox
325

    
326
Draw a colored box on the input image.
327

    
328
It accepts the syntax:
329
@example
330
drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
331
@end example
332

    
333
@table @option
334

    
335
@item x, y
336
Specify the top left corner coordinates of the box. Default to 0.
337

    
338
@item width, height
339
Specify the width and height of the box, if 0 they are interpreted as
340
the input width and height. Default to 0.
341

    
342
@item color
343
Specify the color of the box to write, it can be the name of a color
344
(case insensitive match) or a 0xRRGGBB[AA] sequence.
345
@end table
346

    
347
Follow some examples:
348
@example
349
# draw a black box around the edge of the input image
350
drawbox
351

    
352
# draw a box with color red and an opacity of 50%
353
drawbox=10:20:200:60:red@@0.5"
354
@end example
355

    
356
@section drawtext
357

    
358
Draw text string or text from specified file on top of video using the
359
libfreetype library.
360

    
361
To enable compilation of this filter you need to configure FFmpeg with
362
@code{--enable-libfreetype}.
363

    
364
The filter also recognizes strftime() sequences in the provided text
365
and expands them accordingly. Check the documentation of strftime().
366

    
367
The filter accepts parameters as a list of @var{key}=@var{value} pairs,
368
separated by ":".
369

    
370
The description of the accepted parameters follows.
371

    
372
@table @option
373

    
374
@item fontfile
375
The font file to be used for drawing text. Path must be included.
376
This parameter is mandatory.
377

    
378
@item text
379
The text string to be drawn. The text must be a sequence of UTF-8
380
encoded characters.
381
This parameter is mandatory if no file is specified with the parameter
382
@var{textfile}.
383

    
384
@item textfile
385
A text file containing text to be drawn. The text must be a sequence
386
of UTF-8 encoded characters.
387

    
388
This parameter is mandatory if no text string is specified with the
389
parameter @var{text}.
390

    
391
If both text and textfile are specified, an error is thrown.
392

    
393
@item x, y
394
The offsets where text will be drawn within the video frame.
395
Relative to the top/left border of the output image.
396

    
397
The default value of @var{x} and @var{y} is 0.
398

    
399
@item fontsize
400
The font size to be used for drawing text.
401
The default value of @var{fontsize} is 16.
402

    
403
@item fontcolor
404
The color to be used for drawing fonts.
405
Either a string (e.g. "red") or in 0xRRGGBB[AA] format
406
(e.g. "0xff000033"), possibly followed by an alpha specifier.
407
The default value of @var{fontcolor} is "black".
408

    
409
@item boxcolor
410
The color to be used for drawing box around text.
411
Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
412
(e.g. "0xff00ff"), possibly followed by an alpha specifier.
413

    
414
The default value of @var{bgcolor} is "white".
415

    
416
@item box
417
Used to draw a box around text using background color.
418
Value should be either 1 (enable) or 0 (disable).
419
The default value of @var{box} is 0.
420

    
421
@item ft_load_flags
422
Flags to be used for loading the fonts.
423

    
424
The flags map the corresponding flags supported by libfreetype, and are
425
a combination of the following values:
426
@table @var
427
@item default
428
@item no_scale
429
@item no_hinting
430
@item render
431
@item no_bitmap
432
@item vertical_layout
433
@item force_autohint
434
@item crop_bitmap
435
@item pedantic
436
@item ignore_global_advance_width
437
@item no_recurse
438
@item ignore_transform
439
@item monochrome
440
@item linear_design
441
@item no_autohint
442
@item end table
443
@end table
444

    
445
Default value is "render".
446

    
447
For more information consult the documentation for the FT_LOAD_*
448
libfreetype flags.
449

    
450
@item tabsize
451
The size in number of spaces to use for rendering the tab.
452
Default value is 4.
453
@end table
454

    
455
For example the command:
456
@example
457
drawtext="fontfile=FreeSerif.ttf: text='Test Text': x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: boxcolor=red@@0.2: box=1"
458
@end example
459

    
460
will draw 'Test Text' with font FreeSerif of size 24 at position
461
(100,50), text color is yellow, and draw a red box around text. Both
462
the text and the box have an opacity of 20%.
463

    
464
Note that the double quotes are not necessary if spaces are not used
465
within the parameter list.
466

    
467
For more information about libfreetype, check:
468
@url{http://www.freetype.org/}.
469

    
470
@section fade
471

    
472
Apply fade-in/out effect to input video.
473

    
474
It accepts the parameters:
475
@var{type}:@var{start_frame}:@var{nb_frames}
476

    
477
@var{type} specifies if the effect type, can be either "in" for
478
fade-in, or "out" for a fade-out effect.
479

    
480
@var{start_frame} specifies the number of the start frame for starting
481
to apply the fade effect.
482

    
483
@var{nb_frames} specifies the number of frames for which the fade
484
effect has to last. At the end of the fade-in effect the output video
485
will have the same intensity as the input video, at the end of the
486
fade-out transition the output video will be completely black.
487

    
488
A few usage examples follow, usable too as test scenarios.
489
@example
490
# fade in first 30 frames of video
491
fade=in:0:30
492

    
493
# fade out last 45 frames of a 200-frame video
494
fade=out:155:45
495

    
496
# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
497
fade=in:0:25, fade=out:975:25
498

    
499
# make first 5 frames black, then fade in from frame 5-24
500
fade=in:5:20
501
@end example
502

    
503
@section fifo
504

    
505
Buffer input images and send them when they are requested.
506

    
507
This filter is mainly useful when auto-inserted by the libavfilter
508
framework.
509

    
510
The filter does not take parameters.
511

    
512
@section format
513

    
514
Convert the input video to one of the specified pixel formats.
515
Libavfilter will try to pick one that is supported for the input to
516
the next filter.
517

    
518
The filter accepts a list of pixel format names, separated by ":",
519
for example "yuv420p:monow:rgb24".
520

    
521
Some examples follow:
522
@example
523
# convert the input video to the format "yuv420p"
524
format=yuv420p
525

    
526
# convert the input video to any of the formats in the list
527
format=yuv420p:yuv444p:yuv410p
528
@end example
529

    
530
@anchor{frei0r}
531
@section frei0r
532

    
533
Apply a frei0r effect to the input video.
534

    
535
To enable compilation of this filter you need to install the frei0r
536
header and configure FFmpeg with --enable-frei0r.
537

    
538
The filter supports the syntax:
539
@example
540
@var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
541
@end example
542

    
543
@var{filter_name} is the name to the frei0r effect to load. If the
544
environment variable @env{FREI0R_PATH} is defined, the frei0r effect
545
is searched in each one of the directories specified by the colon
546
separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
547
paths, which are in this order: @file{HOME/.frei0r-1/lib/},
548
@file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
549

    
550
@var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
551
for the frei0r effect.
552

    
553
A frei0r effect parameter can be a boolean (whose values are specified
554
with "y" and "n"), a double, a color (specified by the syntax
555
@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
556
numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
557
description), a position (specified by the syntax @var{X}/@var{Y},
558
@var{X} and @var{Y} being float numbers) and a string.
559

    
560
The number and kind of parameters depend on the loaded effect. If an
561
effect parameter is not specified the default value is set.
562

    
563
Some examples follow:
564
@example
565
# apply the distort0r effect, set the first two double parameters
566
frei0r=distort0r:0.5:0.01
567

    
568
# apply the colordistance effect, takes a color as first parameter
569
frei0r=colordistance:0.2/0.3/0.4
570
frei0r=colordistance:violet
571
frei0r=colordistance:0x112233
572

    
573
# apply the perspective effect, specify the top left and top right
574
# image positions
575
frei0r=perspective:0.2/0.2:0.8/0.2
576
@end example
577

    
578
For more information see:
579
@url{http://piksel.org/frei0r}
580

    
581
@section gradfun
582

    
583
Fix the banding artifacts that are sometimes introduced into nearly flat
584
regions by truncation to 8bit colordepth.
585
Interpolate the gradients that should go where the bands are, and
586
dither them.
587

    
588
The filter takes two optional parameters, separated by ':':
589
@var{strength}:@var{radius}
590

    
591
@var{strength} is the maximum amount by which the filter will change
592
any one pixel. Also the threshold for detecting nearly flat
593
regions. Acceptable values range from .51 to 255, default value is
594
1.2, out-of-range values will be clipped to the valid range.
595

    
596
@var{radius} is the neighborhood to fit the gradient to. A larger
597
radius makes for smoother gradients, but also prevents the filter from
598
modifying the pixels near detailed regions. Acceptable values are
599
8-32, default value is 16, out-of-range values will be clipped to the
600
valid range.
601

    
602
@example
603
# default parameters
604
gradfun=1.2:16
605

    
606
# omitting radius
607
gradfun=1.2
608
@end example
609

    
610
@section hflip
611

    
612
Flip the input video horizontally.
613

    
614
For example to horizontally flip the video in input with
615
@file{ffmpeg}:
616
@example
617
ffmpeg -i in.avi -vf "hflip" out.avi
618
@end example
619

    
620
@section hqdn3d
621

    
622
High precision/quality 3d denoise filter. This filter aims to reduce
623
image noise producing smooth images and making still images really
624
still. It should enhance compressibility.
625

    
626
It accepts the following optional parameters:
627
@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
628

    
629
@table @option
630
@item luma_spatial
631
a non-negative float number which specifies spatial luma strength,
632
defaults to 4.0
633

    
634
@item chroma_spatial
635
a non-negative float number which specifies spatial chroma strength,
636
defaults to 3.0*@var{luma_spatial}/4.0
637

    
638
@item luma_tmp
639
a float number which specifies luma temporal strength, defaults to
640
6.0*@var{luma_spatial}/4.0
641

    
642
@item chroma_tmp
643
a float number which specifies chroma temporal strength, defaults to
644
@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
645
@end table
646

    
647
@section mp
648

    
649
Apply an MPlayer filter to the input video.
650

    
651
This filter provides a wrapper around most of the filters of
652
MPlayer/MEncoder.
653

    
654
This wrapper is considered experimental. Some of the wrapped filters
655
may not work properly and we may drop support for them, as they will
656
be implemented natively into FFmpeg. Thus you should avoid
657
depending on them when writing portable scripts.
658

    
659
The filters accepts the parameters:
660
@var{filter_name}[:=]@var{filter_params}
661

    
662
@var{filter_name} is the name of a supported MPlayer filter,
663
@var{filter_params} is a string containing the parameters accepted by
664
the named filter.
665

    
666
The list of the currently supported filters follows:
667
@table @var
668
@item 2xsai
669
@item blackframe
670
@item boxblur
671
@item cropdetect
672
@item decimate
673
@item delogo
674
@item denoise3d
675
@item detc
676
@item dint
677
@item divtc
678
@item down3dright
679
@item dsize
680
@item eq2
681
@item eq
682
@item field
683
@item fil
684
@item fixpts
685
@item framestep
686
@item fspp
687
@item geq
688
@item gradfun
689
@item harddup
690
@item hqdn3d
691
@item hue
692
@item il
693
@item ilpack
694
@item ivtc
695
@item kerndeint
696
@item mcdeint
697
@item mirror
698
@item noise
699
@item ow
700
@item palette
701
@item perspective
702
@item phase
703
@item pp7
704
@item pullup
705
@item qp
706
@item rectangle
707
@item remove_logo
708
@item rgbtest
709
@item rotate
710
@item sab
711
@item screenshot
712
@item smartblur
713
@item softpulldown
714
@item softskip
715
@item spp
716
@item swapuv
717
@item telecine
718
@item test
719
@item tile
720
@item tinterlace
721
@item unsharp
722
@item uspp
723
@item yuvcsp
724
@item yvu9
725
@end table
726

    
727
The parameter syntax and behavior for the listed filters are the same
728
of the corresponding MPlayer filters. For detailed instructions check
729
the "VIDEO FILTERS" section in the MPlayer manual.
730

    
731
Some examples follow:
732
@example
733
# remove a logo by interpolating the surrounding pixels
734
mp=delogo=200:200:80:20:1
735

    
736
# adjust gamma, brightness, contrast
737
mp=eq2=1.0:2:0.5
738

    
739
# tweak hue and saturation
740
mp=hue=100:-10
741
@end example
742

    
743
See also mplayer(1), @url{http://www.mplayerhq.hu/}.
744

    
745
@section noformat
746

    
747
Force libavfilter not to use any of the specified pixel formats for the
748
input to the next filter.
749

    
750
The filter accepts a list of pixel format names, separated by ":",
751
for example "yuv420p:monow:rgb24".
752

    
753
Some examples follow:
754
@example
755
# force libavfilter to use a format different from "yuv420p" for the
756
# input to the vflip filter
757
noformat=yuv420p,vflip
758

    
759
# convert the input video to any of the formats not contained in the list
760
noformat=yuv420p:yuv444p:yuv410p
761
@end example
762

    
763
@section null
764

    
765
Pass the video source unchanged to the output.
766

    
767
@section ocv
768

    
769
Apply video transform using libopencv.
770

    
771
To enable this filter install libopencv library and headers and
772
configure FFmpeg with --enable-libopencv.
773

    
774
The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
775

    
776
@var{filter_name} is the name of the libopencv filter to apply.
777

    
778
@var{filter_params} specifies the parameters to pass to the libopencv
779
filter. If not specified the default values are assumed.
780

    
781
Refer to the official libopencv documentation for more precise
782
informations:
783
@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
784

    
785
Follows the list of supported libopencv filters.
786

    
787
@anchor{dilate}
788
@subsection dilate
789

    
790
Dilate an image by using a specific structuring element.
791
This filter corresponds to the libopencv function @code{cvDilate}.
792

    
793
It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
794

    
795
@var{struct_el} represents a structuring element, and has the syntax:
796
@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
797

    
798
@var{cols} and @var{rows} represent the number of colums and rows of
799
the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
800
point, and @var{shape} the shape for the structuring element, and
801
can be one of the values "rect", "cross", "ellipse", "custom".
802

    
803
If the value for @var{shape} is "custom", it must be followed by a
804
string of the form "=@var{filename}". The file with name
805
@var{filename} is assumed to represent a binary image, with each
806
printable character corresponding to a bright pixel. When a custom
807
@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
808
or columns and rows of the read file are assumed instead.
809

    
810
The default value for @var{struct_el} is "3x3+0x0/rect".
811

    
812
@var{nb_iterations} specifies the number of times the transform is
813
applied to the image, and defaults to 1.
814

    
815
Follow some example:
816
@example
817
# use the default values
818
ocv=dilate
819

    
820
# dilate using a structuring element with a 5x5 cross, iterate two times
821
ocv=dilate=5x5+2x2/cross:2
822

    
823
# read the shape from the file diamond.shape, iterate two times
824
# the file diamond.shape may contain a pattern of characters like this:
825
#   *
826
#  ***
827
# *****
828
#  ***
829
#   *
830
# the specified cols and rows are ignored (but not the anchor point coordinates)
831
ocv=0x0+2x2/custom=diamond.shape:2
832
@end example
833

    
834
@subsection erode
835

    
836
Erode an image by using a specific structuring element.
837
This filter corresponds to the libopencv function @code{cvErode}.
838

    
839
The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
840
with the same meaning and use of those of the dilate filter
841
(@pxref{dilate}).
842

    
843
@subsection smooth
844

    
845
Smooth the input video.
846

    
847
The filter takes the following parameters:
848
@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
849

    
850
@var{type} is the type of smooth filter to apply, and can be one of
851
the following values: "blur", "blur_no_scale", "median", "gaussian",
852
"bilateral". The default value is "gaussian".
853

    
854
@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
855
parameters whose meanings depend on smooth type. @var{param1} and
856
@var{param2} accept integer positive values or 0, @var{param3} and
857
@var{param4} accept float values.
858

    
859
The default value for @var{param1} is 3, the default value for the
860
other parameters is 0.
861

    
862
These parameters correspond to the parameters assigned to the
863
libopencv function @code{cvSmooth}.
864

    
865
@section overlay
866

    
867
Overlay one video on top of another.
868

    
869
It takes two inputs and one output, the first input is the "main"
870
video on which the second input is overlayed.
871

    
872
It accepts the parameters: @var{x}:@var{y}.
873

    
874
@var{x} is the x coordinate of the overlayed video on the main video,
875
@var{y} is the y coordinate. The parameters are expressions containing
876
the following parameters:
877

    
878
@table @option
879
@item main_w, main_h
880
main input width and height
881

    
882
@item W, H
883
same as @var{main_w} and @var{main_h}
884

    
885
@item overlay_w, overlay_h
886
overlay input width and height
887

    
888
@item w, h
889
same as @var{overlay_w} and @var{overlay_h}
890
@end table
891

    
892
Be aware that frames are taken from each input video in timestamp
893
order, hence, if their initial timestamps differ, it is a a good idea
894
to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
895
have them begin in the same zero timestamp, as it does the example for
896
the @var{movie} filter.
897

    
898
Follow some examples:
899
@example
900
# draw the overlay at 10 pixels from the bottom right
901
# corner of the main video.
902
overlay=main_w-overlay_w-10:main_h-overlay_h-10
903

    
904
# insert a transparent PNG logo in the bottom left corner of the input
905
movie=logo.png [logo];
906
[in][logo] overlay=10:main_h-overlay_h-10 [out]
907

    
908
# insert 2 different transparent PNG logos (second logo on bottom
909
# right corner):
910
movie=logo1.png [logo1];
911
movie=logo2.png [logo2];
912
[in][logo1]       overlay=10:H-h-10 [in+logo1];
913
[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
914

    
915
# add a transparent color layer on top of the main video,
916
# WxH specifies the size of the main input to the overlay filter
917
color=red@.3:WxH [over]; [in][over] overlay [out]
918
@end example
919

    
920
You can chain togheter more overlays but the efficiency of such
921
approach is yet to be tested.
922

    
923
@section pad
924

    
925
Add paddings to the input image, and places the original input at the
926
given coordinates @var{x}, @var{y}.
927

    
928
It accepts the following parameters:
929
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
930

    
931
Follows the description of the accepted parameters.
932

    
933
@table @option
934
@item width, height
935

    
936
Specify the size of the output image with the paddings added. If the
937
value for @var{width} or @var{height} is 0, the corresponding input size
938
is used for the output.
939

    
940
The default value of @var{width} and @var{height} is 0.
941

    
942
@item x, y
943

    
944
Specify the offsets where to place the input image in the padded area
945
with respect to the top/left border of the output image.
946

    
947
The default value of @var{x} and @var{y} is 0.
948

    
949
@item color
950

    
951
Specify the color of the padded area, it can be the name of a color
952
(case insensitive match) or a 0xRRGGBB[AA] sequence.
953

    
954
The default value of @var{color} is "black".
955

    
956
@end table
957

    
958
For example:
959

    
960
@example
961
# Add paddings with color "violet" to the input video. Output video
962
# size is 640x480, the top-left corner of the input video is placed at
963
# row 0, column 40.
964
pad=640:480:0:40:violet
965
@end example
966

    
967
@section pixdesctest
968

    
969
Pixel format descriptor test filter, mainly useful for internal
970
testing. The output video should be equal to the input video.
971

    
972
For example:
973
@example
974
format=monow, pixdesctest
975
@end example
976

    
977
can be used to test the monowhite pixel format descriptor definition.
978

    
979
@section scale
980

    
981
Scale the input video to @var{width}:@var{height} and/or convert the image format.
982

    
983
For example the command:
984

    
985
@example
986
./ffmpeg -i in.avi -vf "scale=200:100" out.avi
987
@end example
988

    
989
will scale the input video to a size of 200x100.
990

    
991
If the input image format is different from the format requested by
992
the next filter, the scale filter will convert the input to the
993
requested format.
994

    
995
If the value for @var{width} or @var{height} is 0, the respective input
996
size is used for the output.
997

    
998
If the value for @var{width} or @var{height} is -1, the scale filter will
999
use, for the respective output size, a value that maintains the aspect
1000
ratio of the input image.
1001

    
1002
The default value of @var{width} and @var{height} is 0.
1003

    
1004
@anchor{setdar}
1005
@section setdar
1006

    
1007
Set the Display Aspect Ratio for the filter output video.
1008

    
1009
This is done by changing the specified Sample (aka Pixel) Aspect
1010
Ratio, according to the following equation:
1011
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1012

    
1013
Keep in mind that this filter does not modify the pixel dimensions of
1014
the video frame. Also the display aspect ratio set by this filter may
1015
be changed by later filters in the filterchain, e.g. in case of
1016
scaling or if another "setdar" or a "setsar" filter is applied.
1017

    
1018
The filter accepts a parameter string which represents the wanted
1019
display aspect ratio.
1020
The parameter can be a floating point number string, or an expression
1021
of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1022
numerator and denominator of the aspect ratio.
1023
If the parameter is not specified, it is assumed the value "0:1".
1024

    
1025
For example to change the display aspect ratio to 16:9, specify:
1026
@example
1027
setdar=16:9
1028
# the above is equivalent to
1029
setdar=1.77777
1030
@end example
1031

    
1032
See also the "setsar" filter documentation (@pxref{setsar}).
1033

    
1034
@section setpts
1035

    
1036
Change the PTS (presentation timestamp) of the input video frames.
1037

    
1038
Accept in input an expression evaluated through the eval API, which
1039
can contain the following constants:
1040

    
1041
@table @option
1042
@item PTS
1043
the presentation timestamp in input
1044

    
1045
@item PI
1046
Greek PI
1047

    
1048
@item PHI
1049
golden ratio
1050

    
1051
@item E
1052
Euler number
1053

    
1054
@item N
1055
the count of the input frame, starting from 0.
1056

    
1057
@item STARTPTS
1058
the PTS of the first video frame
1059

    
1060
@item INTERLACED
1061
tell if the current frame is interlaced
1062

    
1063
@item POS
1064
original position in the file of the frame, or undefined if undefined
1065
for the current frame
1066

    
1067
@item PREV_INPTS
1068
previous input PTS
1069

    
1070
@item PREV_OUTPTS
1071
previous output PTS
1072

    
1073
@end table
1074

    
1075
Some examples follow:
1076

    
1077
@example
1078
# start counting PTS from zero
1079
setpts=PTS-STARTPTS
1080

    
1081
# fast motion
1082
setpts=0.5*PTS
1083

    
1084
# slow motion
1085
setpts=2.0*PTS
1086

    
1087
# fixed rate 25 fps
1088
setpts=N/(25*TB)
1089

    
1090
# fixed rate 25 fps with some jitter
1091
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1092
@end example
1093

    
1094
@anchor{setsar}
1095
@section setsar
1096

    
1097
Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1098

    
1099
Note that as a consequence of the application of this filter, the
1100
output display aspect ratio will change according to the following
1101
equation:
1102
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1103

    
1104
Keep in mind that the sample aspect ratio set by this filter may be
1105
changed by later filters in the filterchain, e.g. if another "setsar"
1106
or a "setdar" filter is applied.
1107

    
1108
The filter accepts a parameter string which represents the wanted
1109
sample aspect ratio.
1110
The parameter can be a floating point number string, or an expression
1111
of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1112
numerator and denominator of the aspect ratio.
1113
If the parameter is not specified, it is assumed the value "0:1".
1114

    
1115
For example to change the sample aspect ratio to 10:11, specify:
1116
@example
1117
setsar=10:11
1118
@end example
1119

    
1120
@section settb
1121

    
1122
Set the timebase to use for the output frames timestamps.
1123
It is mainly useful for testing timebase configuration.
1124

    
1125
It accepts in input an arithmetic expression representing a rational.
1126
The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1127
default timebase), and "intb" (the input timebase).
1128

    
1129
The default value for the input is "intb".
1130

    
1131
Follow some examples.
1132

    
1133
@example
1134
# set the timebase to 1/25
1135
settb=1/25
1136

    
1137
# set the timebase to 1/10
1138
settb=0.1
1139

    
1140
#set the timebase to 1001/1000
1141
settb=1+0.001
1142

    
1143
#set the timebase to 2*intb
1144
settb=2*intb
1145

    
1146
#set the default timebase value
1147
settb=AVTB
1148
@end example
1149

    
1150
@section slicify
1151

    
1152
Pass the images of input video on to next video filter as multiple
1153
slices.
1154

    
1155
@example
1156
./ffmpeg -i in.avi -vf "slicify=32" out.avi
1157
@end example
1158

    
1159
The filter accepts the slice height as parameter. If the parameter is
1160
not specified it will use the default value of 16.
1161

    
1162
Adding this in the beginning of filter chains should make filtering
1163
faster due to better use of the memory cache.
1164

    
1165
@section transpose
1166

    
1167
Transpose rows with columns in the input video and optionally flip it.
1168

    
1169
It accepts a parameter representing an integer, which can assume the
1170
values:
1171

    
1172
@table @samp
1173
@item 0
1174
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1175
@example
1176
L.R     L.l
1177
. . ->  . .
1178
l.r     R.r
1179
@end example
1180

    
1181
@item 1
1182
Rotate by 90 degrees clockwise, that is:
1183
@example
1184
L.R     l.L
1185
. . ->  . .
1186
l.r     r.R
1187
@end example
1188

    
1189
@item 2
1190
Rotate by 90 degrees counterclockwise, that is:
1191
@example
1192
L.R     R.r
1193
. . ->  . .
1194
l.r     L.l
1195
@end example
1196

    
1197
@item 3
1198
Rotate by 90 degrees clockwise and vertically flip, that is:
1199
@example
1200
L.R     r.R
1201
. . ->  . .
1202
l.r     l.L
1203
@end example
1204
@end table
1205

    
1206
@section unsharp
1207

    
1208
Sharpen or blur the input video.
1209

    
1210
It accepts the following parameters:
1211
@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1212

    
1213
Negative values for the amount will blur the input video, while positive
1214
values will sharpen. All parameters are optional and default to the
1215
equivalent of the string '5:5:1.0:0:0:0.0'.
1216

    
1217
@table @option
1218

    
1219
@item luma_msize_x
1220
Set the luma matrix horizontal size. It can be an integer between 3
1221
and 13, default value is 5.
1222

    
1223
@item luma_msize_y
1224
Set the luma matrix vertical size. It can be an integer between 3
1225
and 13, default value is 5.
1226

    
1227
@item luma_amount
1228
Set the luma effect strength. It can be a float number between -2.0
1229
and 5.0, default value is 1.0.
1230

    
1231
@item chroma_msize_x
1232
Set the chroma matrix horizontal size. It can be an integer between 3
1233
and 13, default value is 0.
1234

    
1235
@item chroma_msize_y
1236
Set the chroma matrix vertical size. It can be an integer between 3
1237
and 13, default value is 0.
1238

    
1239
@item luma_amount
1240
Set the chroma effect strength. It can be a float number between -2.0
1241
and 5.0, default value is 0.0.
1242

    
1243
@end table
1244

    
1245
@example
1246
# Strong luma sharpen effect parameters
1247
unsharp=7:7:2.5
1248

    
1249
# Strong blur of both luma and chroma parameters
1250
unsharp=7:7:-2:7:7:-2
1251

    
1252
# Use the default values with @command{ffmpeg}
1253
./ffmpeg -i in.avi -vf "unsharp" out.mp4
1254
@end example
1255

    
1256
@section vflip
1257

    
1258
Flip the input video vertically.
1259

    
1260
@example
1261
./ffmpeg -i in.avi -vf "vflip" out.avi
1262
@end example
1263

    
1264
@section yadif
1265

    
1266
Deinterlace the input video ("yadif" means "yet another deinterlacing
1267
filter").
1268

    
1269
It accepts the optional parameters: @var{mode}:@var{parity}.
1270

    
1271
@var{mode} specifies the interlacing mode to adopt, accepts one of the
1272
following values:
1273

    
1274
@table @option
1275
@item 0
1276
output 1 frame for each frame
1277
@item 1
1278
output 1 frame for each field
1279
@item 2
1280
like 0 but skips spatial interlacing check
1281
@item 3
1282
like 1 but skips spatial interlacing check
1283
@end table
1284

    
1285
Default value is 0.
1286

    
1287
@var{parity} specifies the picture field parity assumed for the input
1288
interlaced video, accepts one of the following values:
1289

    
1290
@table @option
1291
@item 0
1292
assume bottom field first
1293
@item 1
1294
assume top field first
1295
@item -1
1296
enable automatic detection
1297
@end table
1298

    
1299
Default value is -1.
1300
If interlacing is unknown or decoder does not export this information,
1301
top field first will be assumed.
1302

    
1303
@c man end VIDEO FILTERS
1304

    
1305
@chapter Video Sources
1306
@c man begin VIDEO SOURCES
1307

    
1308
Below is a description of the currently available video sources.
1309

    
1310
@section buffer
1311

    
1312
Buffer video frames, and make them available to the filter chain.
1313

    
1314
This source is mainly intended for a programmatic use, in particular
1315
through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1316

    
1317
It accepts the following parameters:
1318
@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1319

    
1320
All the parameters need to be explicitely defined.
1321

    
1322
Follows the list of the accepted parameters.
1323

    
1324
@table @option
1325

    
1326
@item width, height
1327
Specify the width and height of the buffered video frames.
1328

    
1329
@item pix_fmt_string
1330
A string representing the pixel format of the buffered video frames.
1331
It may be a number corresponding to a pixel format, or a pixel format
1332
name.
1333

    
1334
@item timebase_num, timebase_den
1335
Specify numerator and denomitor of the timebase assumed by the
1336
timestamps of the buffered frames.
1337

    
1338
@item sample_aspect_ratio.num, sample_aspect_ratio.den
1339
Specify numerator and denominator of the sample aspect ratio assumed
1340
by the video frames.
1341
@end table
1342

    
1343
For example:
1344
@example
1345
buffer=320:240:yuv410p:1:24:1:1
1346
@end example
1347

    
1348
will instruct the source to accept video frames with size 320x240 and
1349
with format "yuv410p", assuming 1/24 as the timestamps timebase and
1350
square pixels (1:1 sample aspect ratio).
1351
Since the pixel format with name "yuv410p" corresponds to the number 6
1352
(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1353
this example corresponds to:
1354
@example
1355
buffer=320:240:6:1:24
1356
@end example
1357

    
1358
@section color
1359

    
1360
Provide an uniformly colored input.
1361

    
1362
It accepts the following parameters:
1363
@var{color}:@var{frame_size}:@var{frame_rate}
1364

    
1365
Follows the description of the accepted parameters.
1366

    
1367
@table @option
1368

    
1369
@item color
1370
Specify the color of the source. It can be the name of a color (case
1371
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1372
alpha specifier. The default value is "black".
1373

    
1374
@item frame_size
1375
Specify the size of the sourced video, it may be a string of the form
1376
@var{width}x@var{heigth}, or the name of a size abbreviation. The
1377
default value is "320x240".
1378

    
1379
@item frame_rate
1380
Specify the frame rate of the sourced video, as the number of frames
1381
generated per second. It has to be a string in the format
1382
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1383
number or a valid video frame rate abbreviation. The default value is
1384
"25".
1385

    
1386
@end table
1387

    
1388
For example the following graph description will generate a red source
1389
with an opacity of 0.2, with size "qcif" and a frame rate of 10
1390
frames per second, which will be overlayed over the source connected
1391
to the pad with identifier "in".
1392

    
1393
@example
1394
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1395
@end example
1396

    
1397
@section movie
1398

    
1399
Read a video stream from a movie container.
1400

    
1401
It accepts the syntax: @var{movie_name}[:@var{options}] where
1402
@var{movie_name} is the name of the resource to read (not necessarily
1403
a file but also a device or a stream accessed through some protocol),
1404
and @var{options} is an optional sequence of @var{key}=@var{value}
1405
pairs, separated by ":".
1406

    
1407
The description of the accepted options follows.
1408

    
1409
@table @option
1410

    
1411
@item format_name, f
1412
Specifies the format assumed for the movie to read, and can be either
1413
the name of a container or an input device. If not specified the
1414
format is guessed from @var{movie_name} or by probing.
1415

    
1416
@item seek_point, sp
1417
Specifies the seek point in seconds, the frames will be output
1418
starting from this seek point, the parameter is evaluated with
1419
@code{av_strtod} so the numerical value may be suffixed by an IS
1420
postfix. Default value is "0".
1421

    
1422
@item stream_index, si
1423
Specifies the index of the video stream to read. If the value is -1,
1424
the best suited video stream will be automatically selected. Default
1425
value is "-1".
1426

    
1427
@end table
1428

    
1429
This filter allows to overlay a second video on top of main input of
1430
a filtergraph as shown in this graph:
1431
@example
1432
input -----------> deltapts0 --> overlay --> output
1433
                                    ^
1434
                                    |
1435
movie --> scale--> deltapts1 -------+
1436
@end example
1437

    
1438
Some examples follow:
1439
@example
1440
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1441
# on top of the input labelled as "in".
1442
movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1443
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1444

    
1445
# read from a video4linux2 device, and overlay it on top of the input
1446
# labelled as "in"
1447
movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1448
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1449

    
1450
@end example
1451

    
1452
@section nullsrc
1453

    
1454
Null video source, never return images. It is mainly useful as a
1455
template and to be employed in analysis / debugging tools.
1456

    
1457
It accepts as optional parameter a string of the form
1458
@var{width}:@var{height}:@var{timebase}.
1459

    
1460
@var{width} and @var{height} specify the size of the configured
1461
source. The default values of @var{width} and @var{height} are
1462
respectively 352 and 288 (corresponding to the CIF size format).
1463

    
1464
@var{timebase} specifies an arithmetic expression representing a
1465
timebase. The expression can contain the constants "PI", "E", "PHI",
1466
"AVTB" (the default timebase), and defaults to the value "AVTB".
1467

    
1468
@section frei0r_src
1469

    
1470
Provide a frei0r source.
1471

    
1472
To enable compilation of this filter you need to install the frei0r
1473
header and configure FFmpeg with --enable-frei0r.
1474

    
1475
The source supports the syntax:
1476
@example
1477
@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1478
@end example
1479

    
1480
@var{size} is the size of the video to generate, may be a string of the
1481
form @var{width}x@var{height} or a frame size abbreviation.
1482
@var{rate} is the rate of the video to generate, may be a string of
1483
the form @var{num}/@var{den} or a frame rate abbreviation.
1484
@var{src_name} is the name to the frei0r source to load. For more
1485
information regarding frei0r and how to set the parameters read the
1486
section "frei0r" (@pxref{frei0r}) in the description of the video
1487
filters.
1488

    
1489
Some examples follow:
1490
@example
1491
# generate a frei0r partik0l source with size 200x200 and framerate 10
1492
# which is overlayed on the overlay filter main input
1493
frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
1494
@end example
1495

    
1496
@c man end VIDEO SOURCES
1497

    
1498
@chapter Video Sinks
1499
@c man begin VIDEO SINKS
1500

    
1501
Below is a description of the currently available video sinks.
1502

    
1503
@section nullsink
1504

    
1505
Null video sink, do absolutely nothing with the input video. It is
1506
mainly useful as a template and to be employed in analysis / debugging
1507
tools.
1508

    
1509
@c man end VIDEO SINKS
1510