c71fd48b6ef2099a13d4eb92c76395d8a3679f29
[libav.git] / doc / filters.texi
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 Libav 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 Libav 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 height
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 height
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 The default value of @var{boxcolor} is "white".
414
415 @item box
416 Used to draw a box around text using background color.
417 Value should be either 1 (enable) or 0 (disable).
418 The default value of @var{box} is 0.
419
420 @item shadowx, shadowy
421 The x and y offsets for the text shadow position with respect to the
422 position of the text. They can be either positive or negative
423 values. Default value for both is "0".
424
425 @item shadowcolor
426 The color to be used for drawing a shadow behind the drawn text. It
427 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
428 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
429 The default value of @var{shadowcolor} is "black".
430
431 @item ft_load_flags
432 Flags to be used for loading the fonts.
433
434 The flags map the corresponding flags supported by libfreetype, and are
435 a combination of the following values:
436 @table @var
437 @item default
438 @item no_scale
439 @item no_hinting
440 @item render
441 @item no_bitmap
442 @item vertical_layout
443 @item force_autohint
444 @item crop_bitmap
445 @item pedantic
446 @item ignore_global_advance_width
447 @item no_recurse
448 @item ignore_transform
449 @item monochrome
450 @item linear_design
451 @item no_autohint
452 @item end table
453 @end table
454
455 Default value is "render".
456
457 For more information consult the documentation for the FT_LOAD_*
458 libfreetype flags.
459
460 @item tabsize
461 The size in number of spaces to use for rendering the tab.
462 Default value is 4.
463 @end table
464
465 For example the command:
466 @example
467 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
468 @end example
469
470 will draw "Test Text" with font FreeSerif, using the default values
471 for the optional parameters.
472
473 The command:
474 @example
475 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
476 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
477 @end example
478
479 will draw 'Test Text' with font FreeSerif of size 24 at position x=100
480 and y=50 (counting from the top-left corner of the screen), text is
481 yellow with a red box around it. Both the text and the box have an
482 opacity of 20%.
483
484 Note that the double quotes are not necessary if spaces are not used
485 within the parameter list.
486
487 For more information about libfreetype, check:
488 @url{http://www.freetype.org/}.
489
490 @section fade
491
492 Apply fade-in/out effect to input video.
493
494 It accepts the parameters:
495 @var{type}:@var{start_frame}:@var{nb_frames}
496
497 @var{type} specifies if the effect type, can be either "in" for
498 fade-in, or "out" for a fade-out effect.
499
500 @var{start_frame} specifies the number of the start frame for starting
501 to apply the fade effect.
502
503 @var{nb_frames} specifies the number of frames for which the fade
504 effect has to last. At the end of the fade-in effect the output video
505 will have the same intensity as the input video, at the end of the
506 fade-out transition the output video will be completely black.
507
508 A few usage examples follow, usable too as test scenarios.
509 @example
510 # fade in first 30 frames of video
511 fade=in:0:30
512
513 # fade out last 45 frames of a 200-frame video
514 fade=out:155:45
515
516 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
517 fade=in:0:25, fade=out:975:25
518
519 # make first 5 frames black, then fade in from frame 5-24
520 fade=in:5:20
521 @end example
522
523 @section fieldorder
524
525 Transform the field order of the input video.
526
527 It accepts one parameter which specifies the required field order that
528 the input interlaced video will be transformed to. The parameter can
529 assume one of the following values:
530
531 @table @option
532 @item 0 or bff
533 output bottom field first
534 @item 1 or tff
535 output top field first
536 @end table
537
538 Default value is "tff".
539
540 Transformation is achieved by shifting the picture content up or down
541 by one line, and filling the remaining line with appropriate picture content.
542 This method is consistent with most broadcast field order converters.
543
544 If the input video is not flagged as being interlaced, or it is already
545 flagged as being of the required output field order then this filter does
546 not alter the incoming video.
547
548 This filter is very useful when converting to or from PAL DV material,
549 which is bottom field first.
550
551 For example:
552 @example
553 ./ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
554 @end example
555
556 @section fifo
557
558 Buffer input images and send them when they are requested.
559
560 This filter is mainly useful when auto-inserted by the libavfilter
561 framework.
562
563 The filter does not take parameters.
564
565 @section format
566
567 Convert the input video to one of the specified pixel formats.
568 Libavfilter will try to pick one that is supported for the input to
569 the next filter.
570
571 The filter accepts a list of pixel format names, separated by ":",
572 for example "yuv420p:monow:rgb24".
573
574 Some examples follow:
575 @example
576 # convert the input video to the format "yuv420p"
577 format=yuv420p
578
579 # convert the input video to any of the formats in the list
580 format=yuv420p:yuv444p:yuv410p
581 @end example
582
583 @anchor{frei0r}
584 @section frei0r
585
586 Apply a frei0r effect to the input video.
587
588 To enable compilation of this filter you need to install the frei0r
589 header and configure Libav with --enable-frei0r.
590
591 The filter supports the syntax:
592 @example
593 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
594 @end example
595
596 @var{filter_name} is the name to the frei0r effect to load. If the
597 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
598 is searched in each one of the directories specified by the colon
599 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
600 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
601 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
602
603 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
604 for the frei0r effect.
605
606 A frei0r effect parameter can be a boolean (whose values are specified
607 with "y" and "n"), a double, a color (specified by the syntax
608 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
609 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
610 description), a position (specified by the syntax @var{X}/@var{Y},
611 @var{X} and @var{Y} being float numbers) and a string.
612
613 The number and kind of parameters depend on the loaded effect. If an
614 effect parameter is not specified the default value is set.
615
616 Some examples follow:
617 @example
618 # apply the distort0r effect, set the first two double parameters
619 frei0r=distort0r:0.5:0.01
620
621 # apply the colordistance effect, takes a color as first parameter
622 frei0r=colordistance:0.2/0.3/0.4
623 frei0r=colordistance:violet
624 frei0r=colordistance:0x112233
625
626 # apply the perspective effect, specify the top left and top right
627 # image positions
628 frei0r=perspective:0.2/0.2:0.8/0.2
629 @end example
630
631 For more information see:
632 @url{http://piksel.org/frei0r}
633
634 @section gradfun
635
636 Fix the banding artifacts that are sometimes introduced into nearly flat
637 regions by truncation to 8bit colordepth.
638 Interpolate the gradients that should go where the bands are, and
639 dither them.
640
641 This filter is designed for playback only. Do not use it prior to
642 lossy compression, because compression tends to lose the dither and
643 bring back the bands.
644
645 The filter takes two optional parameters, separated by ':':
646 @var{strength}:@var{radius}
647
648 @var{strength} is the maximum amount by which the filter will change
649 any one pixel. Also the threshold for detecting nearly flat
650 regions. Acceptable values range from .51 to 255, default value is
651 1.2, out-of-range values will be clipped to the valid range.
652
653 @var{radius} is the neighborhood to fit the gradient to. A larger
654 radius makes for smoother gradients, but also prevents the filter from
655 modifying the pixels near detailed regions. Acceptable values are
656 8-32, default value is 16, out-of-range values will be clipped to the
657 valid range.
658
659 @example
660 # default parameters
661 gradfun=1.2:16
662
663 # omitting radius
664 gradfun=1.2
665 @end example
666
667 @section hflip
668
669 Flip the input video horizontally.
670
671 For example to horizontally flip the video in input with
672 @file{ffmpeg}:
673 @example
674 ffmpeg -i in.avi -vf "hflip" out.avi
675 @end example
676
677 @section hqdn3d
678
679 High precision/quality 3d denoise filter. This filter aims to reduce
680 image noise producing smooth images and making still images really
681 still. It should enhance compressibility.
682
683 It accepts the following optional parameters:
684 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
685
686 @table @option
687 @item luma_spatial
688 a non-negative float number which specifies spatial luma strength,
689 defaults to 4.0
690
691 @item chroma_spatial
692 a non-negative float number which specifies spatial chroma strength,
693 defaults to 3.0*@var{luma_spatial}/4.0
694
695 @item luma_tmp
696 a float number which specifies luma temporal strength, defaults to
697 6.0*@var{luma_spatial}/4.0
698
699 @item chroma_tmp
700 a float number which specifies chroma temporal strength, defaults to
701 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
702 @end table
703
704 @section lut, lutrgb, lutyuv
705
706 Compute a look-up table for binding each pixel component input value
707 to an output value, and apply it to input video.
708
709 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
710 to an RGB input video.
711
712 These filters accept in input a ":"-separated list of options, which
713 specify the expressions used for computing the lookup table for the
714 corresponding pixel component values.
715
716 The @var{lut} filter requires either YUV or RGB pixel formats in
717 input, and accepts the options:
718 @table @option
719 @var{c0} (first pixel component)
720 @var{c1} (second pixel component)
721 @var{c2} (third pixel component)
722 @var{c3} (fourth pixel component, corresponds to the alpha component)
723 @end table
724
725 The exact component associated to each option depends on the format in
726 input.
727
728 The @var{lutrgb} filter requires RGB pixel formats in input, and
729 accepts the options:
730 @table @option
731 @var{r} (red component)
732 @var{g} (green component)
733 @var{b} (blue component)
734 @var{a} (alpha component)
735 @end table
736
737 The @var{lutyuv} filter requires YUV pixel formats in input, and
738 accepts the options:
739 @table @option
740 @var{y} (Y/luminance component)
741 @var{u} (U/Cb component)
742 @var{v} (V/Cr component)
743 @var{a} (alpha component)
744 @end table
745
746 The expressions can contain the following constants and functions:
747
748 @table @option
749 @item E, PI, PHI
750 the corresponding mathematical approximated values for e
751 (euler number), pi (greek PI), PHI (golden ratio)
752
753 @item w, h
754 the input width and heigth
755
756 @item val
757 input value for the pixel component
758
759 @item clipval
760 the input value clipped in the @var{minval}-@var{maxval} range
761
762 @item maxval
763 maximum value for the pixel component
764
765 @item minval
766 minimum value for the pixel component
767
768 @item negval
769 the negated value for the pixel component value clipped in the
770 @var{minval}-@var{maxval} range , it corresponds to the expression
771 "maxval-clipval+minval"
772
773 @item clip(val)
774 the computed value in @var{val} clipped in the
775 @var{minval}-@var{maxval} range
776
777 @item gammaval(gamma)
778 the computed gamma correction value of the pixel component value
779 clipped in the @var{minval}-@var{maxval} range, corresponds to the
780 expression
781 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
782
783 @end table
784
785 All expressions default to "val".
786
787 Some examples follow:
788 @example
789 # negate input video
790 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
791 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
792
793 # the above is the same as
794 lutrgb="r=negval:g=negval:b=negval"
795 lutyuv="y=negval:u=negval:v=negval"
796
797 # negate luminance
798 lutyuv=negval
799
800 # remove chroma components, turns the video into a graytone image
801 lutyuv="u=128:v=128"
802
803 # apply a luma burning effect
804 lutyuv="y=2*val"
805
806 # remove green and blue components
807 lutrgb="g=0:b=0"
808
809 # set a constant alpha channel value on input
810 format=rgba,lutrgb=a="maxval-minval/2"
811
812 # correct luminance gamma by a 0.5 factor
813 lutyuv=y=gammaval(0.5)
814 @end example
815
816 @section negate
817
818 Negate input video.
819
820 This filter accepts an integer in input, if non-zero it negates the
821 alpha component (if available). The default value in input is 0.
822
823 Force libavfilter not to use any of the specified pixel formats for the
824 input to the next filter.
825
826 The filter accepts a list of pixel format names, separated by ":",
827 for example "yuv420p:monow:rgb24".
828
829 Some examples follow:
830 @example
831 # force libavfilter to use a format different from "yuv420p" for the
832 # input to the vflip filter
833 noformat=yuv420p,vflip
834
835 # convert the input video to any of the formats not contained in the list
836 noformat=yuv420p:yuv444p:yuv410p
837 @end example
838
839 @section null
840
841 Pass the video source unchanged to the output.
842
843 @section ocv
844
845 Apply video transform using libopencv.
846
847 To enable this filter install libopencv library and headers and
848 configure Libav with --enable-libopencv.
849
850 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
851
852 @var{filter_name} is the name of the libopencv filter to apply.
853
854 @var{filter_params} specifies the parameters to pass to the libopencv
855 filter. If not specified the default values are assumed.
856
857 Refer to the official libopencv documentation for more precise
858 informations:
859 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
860
861 Follows the list of supported libopencv filters.
862
863 @anchor{dilate}
864 @subsection dilate
865
866 Dilate an image by using a specific structuring element.
867 This filter corresponds to the libopencv function @code{cvDilate}.
868
869 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
870
871 @var{struct_el} represents a structuring element, and has the syntax:
872 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
873
874 @var{cols} and @var{rows} represent the number of colums and rows of
875 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
876 point, and @var{shape} the shape for the structuring element, and
877 can be one of the values "rect", "cross", "ellipse", "custom".
878
879 If the value for @var{shape} is "custom", it must be followed by a
880 string of the form "=@var{filename}". The file with name
881 @var{filename} is assumed to represent a binary image, with each
882 printable character corresponding to a bright pixel. When a custom
883 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
884 or columns and rows of the read file are assumed instead.
885
886 The default value for @var{struct_el} is "3x3+0x0/rect".
887
888 @var{nb_iterations} specifies the number of times the transform is
889 applied to the image, and defaults to 1.
890
891 Follow some example:
892 @example
893 # use the default values
894 ocv=dilate
895
896 # dilate using a structuring element with a 5x5 cross, iterate two times
897 ocv=dilate=5x5+2x2/cross:2
898
899 # read the shape from the file diamond.shape, iterate two times
900 # the file diamond.shape may contain a pattern of characters like this:
901 # *
902 # ***
903 # *****
904 # ***
905 # *
906 # the specified cols and rows are ignored (but not the anchor point coordinates)
907 ocv=0x0+2x2/custom=diamond.shape:2
908 @end example
909
910 @subsection erode
911
912 Erode an image by using a specific structuring element.
913 This filter corresponds to the libopencv function @code{cvErode}.
914
915 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
916 with the same syntax and semantics as the @ref{dilate} filter.
917
918 @subsection smooth
919
920 Smooth the input video.
921
922 The filter takes the following parameters:
923 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
924
925 @var{type} is the type of smooth filter to apply, and can be one of
926 the following values: "blur", "blur_no_scale", "median", "gaussian",
927 "bilateral". The default value is "gaussian".
928
929 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
930 parameters whose meanings depend on smooth type. @var{param1} and
931 @var{param2} accept integer positive values or 0, @var{param3} and
932 @var{param4} accept float values.
933
934 The default value for @var{param1} is 3, the default value for the
935 other parameters is 0.
936
937 These parameters correspond to the parameters assigned to the
938 libopencv function @code{cvSmooth}.
939
940 @section overlay
941
942 Overlay one video on top of another.
943
944 It takes two inputs and one output, the first input is the "main"
945 video on which the second input is overlayed.
946
947 It accepts the parameters: @var{x}:@var{y}.
948
949 @var{x} is the x coordinate of the overlayed video on the main video,
950 @var{y} is the y coordinate. The parameters are expressions containing
951 the following parameters:
952
953 @table @option
954 @item main_w, main_h
955 main input width and height
956
957 @item W, H
958 same as @var{main_w} and @var{main_h}
959
960 @item overlay_w, overlay_h
961 overlay input width and height
962
963 @item w, h
964 same as @var{overlay_w} and @var{overlay_h}
965 @end table
966
967 Be aware that frames are taken from each input video in timestamp
968 order, hence, if their initial timestamps differ, it is a a good idea
969 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
970 have them begin in the same zero timestamp, as it does the example for
971 the @var{movie} filter.
972
973 Follow some examples:
974 @example
975 # draw the overlay at 10 pixels from the bottom right
976 # corner of the main video.
977 overlay=main_w-overlay_w-10:main_h-overlay_h-10
978
979 # insert a transparent PNG logo in the bottom left corner of the input
980 movie=logo.png [logo];
981 [in][logo] overlay=10:main_h-overlay_h-10 [out]
982
983 # insert 2 different transparent PNG logos (second logo on bottom
984 # right corner):
985 movie=logo1.png [logo1];
986 movie=logo2.png [logo2];
987 [in][logo1] overlay=10:H-h-10 [in+logo1];
988 [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
989
990 # add a transparent color layer on top of the main video,
991 # WxH specifies the size of the main input to the overlay filter
992 color=red@.3:WxH [over]; [in][over] overlay [out]
993 @end example
994
995 You can chain togheter more overlays but the efficiency of such
996 approach is yet to be tested.
997
998 @section pad
999
1000 Add paddings to the input image, and places the original input at the
1001 given coordinates @var{x}, @var{y}.
1002
1003 It accepts the following parameters:
1004 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1005
1006 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1007 expressions containing the following constants:
1008
1009 @table @option
1010 @item E, PI, PHI
1011 the corresponding mathematical approximated values for e
1012 (euler number), pi (greek PI), phi (golden ratio)
1013
1014 @item in_w, in_h
1015 the input video width and height
1016
1017 @item iw, ih
1018 same as @var{in_w} and @var{in_h}
1019
1020 @item out_w, out_h
1021 the output width and height, that is the size of the padded area as
1022 specified by the @var{width} and @var{height} expressions
1023
1024 @item ow, oh
1025 same as @var{out_w} and @var{out_h}
1026
1027 @item x, y
1028 x and y offsets as specified by the @var{x} and @var{y}
1029 expressions, or NAN if not yet specified
1030
1031 @item a
1032 input display aspect ratio, same as @var{iw} / @var{ih}
1033
1034 @item hsub, vsub
1035 horizontal and vertical chroma subsample values. For example for the
1036 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1037 @end table
1038
1039 Follows the description of the accepted parameters.
1040
1041 @table @option
1042 @item width, height
1043
1044 Specify the size of the output image with the paddings added. If the
1045 value for @var{width} or @var{height} is 0, the corresponding input size
1046 is used for the output.
1047
1048 The @var{width} expression can reference the value set by the
1049 @var{height} expression, and viceversa.
1050
1051 The default value of @var{width} and @var{height} is 0.
1052
1053 @item x, y
1054
1055 Specify the offsets where to place the input image in the padded area
1056 with respect to the top/left border of the output image.
1057
1058 The @var{x} expression can reference the value set by the @var{y}
1059 expression, and viceversa.
1060
1061 The default value of @var{x} and @var{y} is 0.
1062
1063 @item color
1064
1065 Specify the color of the padded area, it can be the name of a color
1066 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1067
1068 The default value of @var{color} is "black".
1069
1070 @end table
1071
1072 Some examples follow:
1073
1074 @example
1075 # Add paddings with color "violet" to the input video. Output video
1076 # size is 640x480, the top-left corner of the input video is placed at
1077 # column 0, row 40.
1078 pad=640:480:0:40:violet
1079
1080 # pad the input to get an output with dimensions increased bt 3/2,
1081 # and put the input video at the center of the padded area
1082 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1083
1084 # pad the input to get a squared output with size equal to the maximum
1085 # value between the input width and height, and put the input video at
1086 # the center of the padded area
1087 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1088
1089 # pad the input to get a final w/h ratio of 16:9
1090 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1091
1092 # double output size and put the input video in the bottom-right
1093 # corner of the output padded area
1094 pad="2*iw:2*ih:ow-iw:oh-ih"
1095 @end example
1096
1097 @section pixdesctest
1098
1099 Pixel format descriptor test filter, mainly useful for internal
1100 testing. The output video should be equal to the input video.
1101
1102 For example:
1103 @example
1104 format=monow, pixdesctest
1105 @end example
1106
1107 can be used to test the monowhite pixel format descriptor definition.
1108
1109 @section scale
1110
1111 Scale the input video to @var{width}:@var{height} and/or convert the image format.
1112
1113 The parameters @var{width} and @var{height} are expressions containing
1114 the following constants:
1115
1116 @table @option
1117 @item E, PI, PHI
1118 the corresponding mathematical approximated values for e
1119 (euler number), pi (greek PI), phi (golden ratio)
1120
1121 @item in_w, in_h
1122 the input width and height
1123
1124 @item iw, ih
1125 same as @var{in_w} and @var{in_h}
1126
1127 @item out_w, out_h
1128 the output (cropped) width and height
1129
1130 @item ow, oh
1131 same as @var{out_w} and @var{out_h}
1132
1133 @item dar, a
1134 input display aspect ratio, same as @var{iw} / @var{ih}
1135
1136 @item sar
1137 input sample aspect ratio
1138
1139 @item hsub, vsub
1140 horizontal and vertical chroma subsample values. For example for the
1141 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1142 @end table
1143
1144 If the input image format is different from the format requested by
1145 the next filter, the scale filter will convert the input to the
1146 requested format.
1147
1148 If the value for @var{width} or @var{height} is 0, the respective input
1149 size is used for the output.
1150
1151 If the value for @var{width} or @var{height} is -1, the scale filter will
1152 use, for the respective output size, a value that maintains the aspect
1153 ratio of the input image.
1154
1155 The default value of @var{width} and @var{height} is 0.
1156
1157 Some examples follow:
1158 @example
1159 # scale the input video to a size of 200x100.
1160 scale=200:100
1161
1162 # scale the input to 2x
1163 scale=2*iw:2*ih
1164 # the above is the same as
1165 scale=2*in_w:2*in_h
1166
1167 # scale the input to half size
1168 scale=iw/2:ih/2
1169
1170 # increase the width, and set the height to the same size
1171 scale=3/2*iw:ow
1172
1173 # seek for Greek harmony
1174 scale=iw:1/PHI*iw
1175 scale=ih*PHI:ih
1176
1177 # increase the height, and set the width to 3/2 of the height
1178 scale=3/2*oh:3/5*ih
1179
1180 # increase the size, but make the size a multiple of the chroma
1181 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1182
1183 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1184 scale='min(500\, iw*3/2):-1'
1185 @end example
1186
1187 @section select
1188 Select frames to pass in output.
1189
1190 It accepts in input an expression, which is evaluated for each input
1191 frame. If the expression is evaluated to a non-zero value, the frame
1192 is selected and passed to the output, otherwise it is discarded.
1193
1194 The expression can contain the following constants:
1195
1196 @table @option
1197 @item PI
1198 Greek PI
1199
1200 @item PHI
1201 golden ratio
1202
1203 @item E
1204 Euler number
1205
1206 @item n
1207 the sequential number of the filtered frame, starting from 0
1208
1209 @item selected_n
1210 the sequential number of the selected frame, starting from 0
1211
1212 @item prev_selected_n
1213 the sequential number of the last selected frame, NAN if undefined
1214
1215 @item TB
1216 timebase of the input timestamps
1217
1218 @item pts
1219 the PTS (Presentation TimeStamp) of the filtered video frame,
1220 expressed in @var{TB} units, NAN if undefined
1221
1222 @item t
1223 the PTS (Presentation TimeStamp) of the filtered video frame,
1224 expressed in seconds, NAN if undefined
1225
1226 @item prev_pts
1227 the PTS of the previously filtered video frame, NAN if undefined
1228
1229 @item prev_selected_pts
1230 the PTS of the last previously filtered video frame, NAN if undefined
1231
1232 @item prev_selected_t
1233 the PTS of the last previously selected video frame, NAN if undefined
1234
1235 @item start_pts
1236 the PTS of the first video frame in the video, NAN if undefined
1237
1238 @item start_t
1239 the time of the first video frame in the video, NAN if undefined
1240
1241 @item pict_type
1242 the type of the filtered frame, can assume one of the following
1243 values:
1244 @table @option
1245 @item I
1246 @item P
1247 @item B
1248 @item S
1249 @item SI
1250 @item SP
1251 @item BI
1252 @end table
1253
1254 @item interlace_type
1255 the frame interlace type, can assume one of the following values:
1256 @table @option
1257 @item PROGRESSIVE
1258 the frame is progressive (not interlaced)
1259 @item TOPFIRST
1260 the frame is top-field-first
1261 @item BOTTOMFIRST
1262 the frame is bottom-field-first
1263 @end table
1264
1265 @item key
1266 1 if the filtered frame is a key-frame, 0 otherwise
1267
1268 @item pos
1269 the position in the file of the filtered frame, -1 if the information
1270 is not available (e.g. for synthetic video)
1271 @end table
1272
1273 The default value of the select expression is "1".
1274
1275 Some examples follow:
1276
1277 @example
1278 # select all frames in input
1279 select
1280
1281 # the above is the same as:
1282 select=1
1283
1284 # skip all frames:
1285 select=0
1286
1287 # select only I-frames
1288 select='eq(pict_type\,I)'
1289
1290 # select one frame every 100
1291 select='not(mod(n\,100))'
1292
1293 # select only frames contained in the 10-20 time interval
1294 select='gte(t\,10)*lte(t\,20)'
1295
1296 # select only I frames contained in the 10-20 time interval
1297 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
1298
1299 # select frames with a minimum distance of 10 seconds
1300 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
1301 @end example
1302
1303 @anchor{setdar}
1304 @section setdar
1305
1306 Set the Display Aspect Ratio for the filter output video.
1307
1308 This is done by changing the specified Sample (aka Pixel) Aspect
1309 Ratio, according to the following equation:
1310 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1311
1312 Keep in mind that this filter does not modify the pixel dimensions of
1313 the video frame. Also the display aspect ratio set by this filter may
1314 be changed by later filters in the filterchain, e.g. in case of
1315 scaling or if another "setdar" or a "setsar" filter is applied.
1316
1317 The filter accepts a parameter string which represents the wanted
1318 display aspect ratio.
1319 The parameter can be a floating point number string, or an expression
1320 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1321 numerator and denominator of the aspect ratio.
1322 If the parameter is not specified, it is assumed the value "0:1".
1323
1324 For example to change the display aspect ratio to 16:9, specify:
1325 @example
1326 setdar=16:9
1327 # the above is equivalent to
1328 setdar=1.77777
1329 @end example
1330
1331 See also the @ref{setsar} filter documentation.
1332
1333 @section setpts
1334
1335 Change the PTS (presentation timestamp) of the input video frames.
1336
1337 Accept in input an expression evaluated through the eval API, which
1338 can contain the following constants:
1339
1340 @table @option
1341 @item PTS
1342 the presentation timestamp in input
1343
1344 @item PI
1345 Greek PI
1346
1347 @item PHI
1348 golden ratio
1349
1350 @item E
1351 Euler number
1352
1353 @item N
1354 the count of the input frame, starting from 0.
1355
1356 @item STARTPTS
1357 the PTS of the first video frame
1358
1359 @item INTERLACED
1360 tell if the current frame is interlaced
1361
1362 @item POS
1363 original position in the file of the frame, or undefined if undefined
1364 for the current frame
1365
1366 @item PREV_INPTS
1367 previous input PTS
1368
1369 @item PREV_OUTPTS
1370 previous output PTS
1371
1372 @end table
1373
1374 Some examples follow:
1375
1376 @example
1377 # start counting PTS from zero
1378 setpts=PTS-STARTPTS
1379
1380 # fast motion
1381 setpts=0.5*PTS
1382
1383 # slow motion
1384 setpts=2.0*PTS
1385
1386 # fixed rate 25 fps
1387 setpts=N/(25*TB)
1388
1389 # fixed rate 25 fps with some jitter
1390 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1391 @end example
1392
1393 @anchor{setsar}
1394 @section setsar
1395
1396 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1397
1398 Note that as a consequence of the application of this filter, the
1399 output display aspect ratio will change according to the following
1400 equation:
1401 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1402
1403 Keep in mind that the sample aspect ratio set by this filter may be
1404 changed by later filters in the filterchain, e.g. if another "setsar"
1405 or a "setdar" filter is applied.
1406
1407 The filter accepts a parameter string which represents the wanted
1408 sample aspect ratio.
1409 The parameter can be a floating point number string, or an expression
1410 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1411 numerator and denominator of the aspect ratio.
1412 If the parameter is not specified, it is assumed the value "0:1".
1413
1414 For example to change the sample aspect ratio to 10:11, specify:
1415 @example
1416 setsar=10:11
1417 @end example
1418
1419 @section settb
1420
1421 Set the timebase to use for the output frames timestamps.
1422 It is mainly useful for testing timebase configuration.
1423
1424 It accepts in input an arithmetic expression representing a rational.
1425 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1426 default timebase), and "intb" (the input timebase).
1427
1428 The default value for the input is "intb".
1429
1430 Follow some examples.
1431
1432 @example
1433 # set the timebase to 1/25
1434 settb=1/25
1435
1436 # set the timebase to 1/10
1437 settb=0.1
1438
1439 #set the timebase to 1001/1000
1440 settb=1+0.001
1441
1442 #set the timebase to 2*intb
1443 settb=2*intb
1444
1445 #set the default timebase value
1446 settb=AVTB
1447 @end example
1448
1449 @section showinfo
1450
1451 Show a line containing various information for each input video frame.
1452 The input video is not modified.
1453
1454 The shown line contains a sequence of key/value pairs of the form
1455 @var{key}:@var{value}.
1456
1457 A description of each shown parameter follows:
1458
1459 @table @option
1460 @item n
1461 sequential number of the input frame, starting from 0
1462
1463 @item pts
1464 Presentation TimeStamp of the input frame, expressed as a number of
1465 time base units. The time base unit depends on the filter input pad.
1466
1467 @item pts_time
1468 Presentation TimeStamp of the input frame, expressed as a number of
1469 seconds
1470
1471 @item pos
1472 position of the frame in the input stream, -1 if this information in
1473 unavailable and/or meanigless (for example in case of synthetic video)
1474
1475 @item fmt
1476 pixel format name
1477
1478 @item sar
1479 sample aspect ratio of the input frame, expressed in the form
1480 @var{num}/@var{den}
1481
1482 @item s
1483 size of the input frame, expressed in the form
1484 @var{width}x@var{height}
1485
1486 @item i
1487 interlaced mode ("P" for "progressive", "T" for top field first, "B"
1488 for bottom field first)
1489
1490 @item iskey
1491 1 if the frame is a key frame, 0 otherwise
1492
1493 @item type
1494 picture type of the input frame ("I" for an I-frame, "P" for a
1495 P-frame, "B" for a B-frame, "?" for unknown type).
1496 Check also the documentation of the @code{AVPictureType} enum and of
1497 the @code{av_get_picture_type_char} function defined in
1498 @file{libavutil/avutil.h}.
1499
1500 @item checksum
1501 Adler-32 checksum of all the planes of the input frame
1502
1503 @item plane_checksum
1504 Adler-32 checksum of each plane of the input frame, expressed in the form
1505 "[@var{c0} @var{c1} @var{c2} @var{c3}]"
1506 @end table
1507
1508 @section slicify
1509
1510 Pass the images of input video on to next video filter as multiple
1511 slices.
1512
1513 @example
1514 ./ffmpeg -i in.avi -vf "slicify=32" out.avi
1515 @end example
1516
1517 The filter accepts the slice height as parameter. If the parameter is
1518 not specified it will use the default value of 16.
1519
1520 Adding this in the beginning of filter chains should make filtering
1521 faster due to better use of the memory cache.
1522
1523 @section transpose
1524
1525 Transpose rows with columns in the input video and optionally flip it.
1526
1527 It accepts a parameter representing an integer, which can assume the
1528 values:
1529
1530 @table @samp
1531 @item 0
1532 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1533 @example
1534 L.R L.l
1535 . . -> . .
1536 l.r R.r
1537 @end example
1538
1539 @item 1
1540 Rotate by 90 degrees clockwise, that is:
1541 @example
1542 L.R l.L
1543 . . -> . .
1544 l.r r.R
1545 @end example
1546
1547 @item 2
1548 Rotate by 90 degrees counterclockwise, that is:
1549 @example
1550 L.R R.r
1551 . . -> . .
1552 l.r L.l
1553 @end example
1554
1555 @item 3
1556 Rotate by 90 degrees clockwise and vertically flip, that is:
1557 @example
1558 L.R r.R
1559 . . -> . .
1560 l.r l.L
1561 @end example
1562 @end table
1563
1564 @section unsharp
1565
1566 Sharpen or blur the input video.
1567
1568 It accepts the following parameters:
1569 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1570
1571 Negative values for the amount will blur the input video, while positive
1572 values will sharpen. All parameters are optional and default to the
1573 equivalent of the string '5:5:1.0:5:5:0.0'.
1574
1575 @table @option
1576
1577 @item luma_msize_x
1578 Set the luma matrix horizontal size. It can be an integer between 3
1579 and 13, default value is 5.
1580
1581 @item luma_msize_y
1582 Set the luma matrix vertical size. It can be an integer between 3
1583 and 13, default value is 5.
1584
1585 @item luma_amount
1586 Set the luma effect strength. It can be a float number between -2.0
1587 and 5.0, default value is 1.0.
1588
1589 @item chroma_msize_x
1590 Set the chroma matrix horizontal size. It can be an integer between 3
1591 and 13, default value is 5.
1592
1593 @item chroma_msize_y
1594 Set the chroma matrix vertical size. It can be an integer between 3
1595 and 13, default value is 5.
1596
1597 @item luma_amount
1598 Set the chroma effect strength. It can be a float number between -2.0
1599 and 5.0, default value is 0.0.
1600
1601 @end table
1602
1603 @example
1604 # Strong luma sharpen effect parameters
1605 unsharp=7:7:2.5
1606
1607 # Strong blur of both luma and chroma parameters
1608 unsharp=7:7:-2:7:7:-2
1609
1610 # Use the default values with @command{ffmpeg}
1611 ./ffmpeg -i in.avi -vf "unsharp" out.mp4
1612 @end example
1613
1614 @section vflip
1615
1616 Flip the input video vertically.
1617
1618 @example
1619 ./ffmpeg -i in.avi -vf "vflip" out.avi
1620 @end example
1621
1622 @section yadif
1623
1624 Deinterlace the input video ("yadif" means "yet another deinterlacing
1625 filter").
1626
1627 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
1628
1629 @var{mode} specifies the interlacing mode to adopt, accepts one of the
1630 following values:
1631
1632 @table @option
1633 @item 0
1634 output 1 frame for each frame
1635 @item 1
1636 output 1 frame for each field
1637 @item 2
1638 like 0 but skips spatial interlacing check
1639 @item 3
1640 like 1 but skips spatial interlacing check
1641 @end table
1642
1643 Default value is 0.
1644
1645 @var{parity} specifies the picture field parity assumed for the input
1646 interlaced video, accepts one of the following values:
1647
1648 @table @option
1649 @item 0
1650 assume top field first
1651 @item 1
1652 assume bottom field first
1653 @item -1
1654 enable automatic detection
1655 @end table
1656
1657 Default value is -1.
1658 If interlacing is unknown or decoder does not export this information,
1659 top field first will be assumed.
1660
1661 @var{auto] specifies if deinterlacer should trust the interlaced flag
1662 and only deinterlace frames marked as interlaced
1663
1664 @table @option
1665 @item 0
1666 deinterlace all frames
1667 @item 1
1668 only deinterlace frames marked as interlaced
1669 @end table
1670
1671 Default value is 0.
1672
1673 @c man end VIDEO FILTERS
1674
1675 @chapter Video Sources
1676 @c man begin VIDEO SOURCES
1677
1678 Below is a description of the currently available video sources.
1679
1680 @section buffer
1681
1682 Buffer video frames, and make them available to the filter chain.
1683
1684 This source is mainly intended for a programmatic use, in particular
1685 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1686
1687 It accepts the following parameters:
1688 @var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1689
1690 All the parameters need to be explicitely defined.
1691
1692 Follows the list of the accepted parameters.
1693
1694 @table @option
1695
1696 @item width, height
1697 Specify the width and height of the buffered video frames.
1698
1699 @item pix_fmt_string
1700 A string representing the pixel format of the buffered video frames.
1701 It may be a number corresponding to a pixel format, or a pixel format
1702 name.
1703
1704 @item timebase_num, timebase_den
1705 Specify numerator and denomitor of the timebase assumed by the
1706 timestamps of the buffered frames.
1707
1708 @item sample_aspect_ratio.num, sample_aspect_ratio.den
1709 Specify numerator and denominator of the sample aspect ratio assumed
1710 by the video frames.
1711 @end table
1712
1713 For example:
1714 @example
1715 buffer=320:240:yuv410p:1:24:1:1
1716 @end example
1717
1718 will instruct the source to accept video frames with size 320x240 and
1719 with format "yuv410p", assuming 1/24 as the timestamps timebase and
1720 square pixels (1:1 sample aspect ratio).
1721 Since the pixel format with name "yuv410p" corresponds to the number 6
1722 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1723 this example corresponds to:
1724 @example
1725 buffer=320:240:6:1:24
1726 @end example
1727
1728 @section color
1729
1730 Provide an uniformly colored input.
1731
1732 It accepts the following parameters:
1733 @var{color}:@var{frame_size}:@var{frame_rate}
1734
1735 Follows the description of the accepted parameters.
1736
1737 @table @option
1738
1739 @item color
1740 Specify the color of the source. It can be the name of a color (case
1741 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1742 alpha specifier. The default value is "black".
1743
1744 @item frame_size
1745 Specify the size of the sourced video, it may be a string of the form
1746 @var{width}x@var{height}, or the name of a size abbreviation. The
1747 default value is "320x240".
1748
1749 @item frame_rate
1750 Specify the frame rate of the sourced video, as the number of frames
1751 generated per second. It has to be a string in the format
1752 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1753 number or a valid video frame rate abbreviation. The default value is
1754 "25".
1755
1756 @end table
1757
1758 For example the following graph description will generate a red source
1759 with an opacity of 0.2, with size "qcif" and a frame rate of 10
1760 frames per second, which will be overlayed over the source connected
1761 to the pad with identifier "in".
1762
1763 @example
1764 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1765 @end example
1766
1767 @section movie
1768
1769 Read a video stream from a movie container.
1770
1771 It accepts the syntax: @var{movie_name}[:@var{options}] where
1772 @var{movie_name} is the name of the resource to read (not necessarily
1773 a file but also a device or a stream accessed through some protocol),
1774 and @var{options} is an optional sequence of @var{key}=@var{value}
1775 pairs, separated by ":".
1776
1777 The description of the accepted options follows.
1778
1779 @table @option
1780
1781 @item format_name, f
1782 Specifies the format assumed for the movie to read, and can be either
1783 the name of a container or an input device. If not specified the
1784 format is guessed from @var{movie_name} or by probing.
1785
1786 @item seek_point, sp
1787 Specifies the seek point in seconds, the frames will be output
1788 starting from this seek point, the parameter is evaluated with
1789 @code{av_strtod} so the numerical value may be suffixed by an IS
1790 postfix. Default value is "0".
1791
1792 @item stream_index, si
1793 Specifies the index of the video stream to read. If the value is -1,
1794 the best suited video stream will be automatically selected. Default
1795 value is "-1".
1796
1797 @end table
1798
1799 This filter allows to overlay a second video on top of main input of
1800 a filtergraph as shown in this graph:
1801 @example
1802 input -----------> deltapts0 --> overlay --> output
1803 ^
1804 |
1805 movie --> scale--> deltapts1 -------+
1806 @end example
1807
1808 Some examples follow:
1809 @example
1810 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1811 # on top of the input labelled as "in".
1812 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1813 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1814
1815 # read from a video4linux2 device, and overlay it on top of the input
1816 # labelled as "in"
1817 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1818 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1819
1820 @end example
1821
1822 @section nullsrc
1823
1824 Null video source, never return images. It is mainly useful as a
1825 template and to be employed in analysis / debugging tools.
1826
1827 It accepts as optional parameter a string of the form
1828 @var{width}:@var{height}:@var{timebase}.
1829
1830 @var{width} and @var{height} specify the size of the configured
1831 source. The default values of @var{width} and @var{height} are
1832 respectively 352 and 288 (corresponding to the CIF size format).
1833
1834 @var{timebase} specifies an arithmetic expression representing a
1835 timebase. The expression can contain the constants "PI", "E", "PHI",
1836 "AVTB" (the default timebase), and defaults to the value "AVTB".
1837
1838 @section frei0r_src
1839
1840 Provide a frei0r source.
1841
1842 To enable compilation of this filter you need to install the frei0r
1843 header and configure Libav with --enable-frei0r.
1844
1845 The source supports the syntax:
1846 @example
1847 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1848 @end example
1849
1850 @var{size} is the size of the video to generate, may be a string of the
1851 form @var{width}x@var{height} or a frame size abbreviation.
1852 @var{rate} is the rate of the video to generate, may be a string of
1853 the form @var{num}/@var{den} or a frame rate abbreviation.
1854 @var{src_name} is the name to the frei0r source to load. For more
1855 information regarding frei0r and how to set the parameters read the
1856 section @ref{frei0r} in the description of the video filters.
1857
1858 Some examples follow:
1859 @example
1860 # generate a frei0r partik0l source with size 200x200 and framerate 10
1861 # which is overlayed on the overlay filter main input
1862 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
1863 @end example
1864
1865 @c man end VIDEO SOURCES
1866
1867 @chapter Video Sinks
1868 @c man begin VIDEO SINKS
1869
1870 Below is a description of the currently available video sinks.
1871
1872 @section nullsink
1873
1874 Null video sink, do absolutely nothing with the input video. It is
1875 mainly useful as a template and to be employed in analysis / debugging
1876 tools.
1877
1878 @c man end VIDEO SINKS
1879