lavfi: port boxblur filter from libmpcodecs
[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 boxblur
187
188 Apply boxblur algorithm to the input video.
189
190 This filter accepts the parameters:
191 @var{luma_power}:@var{luma_radius}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
192
193 Chroma and alpha parameters are optional, if not specified they default
194 to the corresponding values set for @var{luma_radius} and
195 @var{luma_power}.
196
197 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
198 the radius in pixels of the box used for blurring the corresponding
199 input plane. They are expressions, and can contain the following
200 constants:
201 @table @option
202 @item w, h
203 the input width and heigth in pixels
204
205 @item cw, ch
206 the input chroma image width and height in pixels
207
208 @item hsub, vsub
209 horizontal and vertical chroma subsample values. For example for the
210 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
211 @end table
212
213 The radius must be a non-negative number, and must not be greater than
214 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
215 and of @code{min(cw,ch)/2} for the chroma planes.
216
217 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
218 how many times the boxblur filter is applied to the corresponding
219 plane.
220
221 Some examples follow:
222
223 @itemize
224
225 @item
226 Apply a boxblur filter with luma, chroma, and alpha radius
227 set to 2:
228 @example
229 boxblur=2:1
230 @end example
231
232 @item
233 Set luma radius to 2, alpha and chroma radius to 0
234 @example
235 boxblur=2:1:0:0:0:0
236 @end example
237
238 @item
239 Set luma and chroma radius to a fraction of the video dimension
240 @example
241 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
242 @end example
243
244 @end itemize
245
246 @section copy
247
248 Copy the input source unchanged to the output. Mainly useful for
249 testing purposes.
250
251 @section crop
252
253 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
254
255 The parameters are expressions containing the following constants:
256
257 @table @option
258 @item E, PI, PHI
259 the corresponding mathematical approximated values for e
260 (euler number), pi (greek PI), PHI (golden ratio)
261
262 @item x, y
263 the computed values for @var{x} and @var{y}. They are evaluated for
264 each new frame.
265
266 @item in_w, in_h
267 the input width and height
268
269 @item iw, ih
270 same as @var{in_w} and @var{in_h}
271
272 @item out_w, out_h
273 the output (cropped) width and height
274
275 @item ow, oh
276 same as @var{out_w} and @var{out_h}
277
278 @item n
279 the number of input frame, starting from 0
280
281 @item pos
282 the position in the file of the input frame, NAN if unknown
283
284 @item t
285 timestamp expressed in seconds, NAN if the input timestamp is unknown
286
287 @end table
288
289 The @var{out_w} and @var{out_h} parameters specify the expressions for
290 the width and height of the output (cropped) video. They are
291 evaluated just at the configuration of the filter.
292
293 The default value of @var{out_w} is "in_w", and the default value of
294 @var{out_h} is "in_h".
295
296 The expression for @var{out_w} may depend on the value of @var{out_h},
297 and the expression for @var{out_h} may depend on @var{out_w}, but they
298 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
299 evaluated after @var{out_w} and @var{out_h}.
300
301 The @var{x} and @var{y} parameters specify the expressions for the
302 position of the top-left corner of the output (non-cropped) area. They
303 are evaluated for each frame. If the evaluated value is not valid, it
304 is approximated to the nearest valid value.
305
306 The default value of @var{x} is "(in_w-out_w)/2", and the default
307 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
308 the center of the input image.
309
310 The expression for @var{x} may depend on @var{y}, and the expression
311 for @var{y} may depend on @var{x}.
312
313 Follow some examples:
314 @example
315 # crop the central input area with size 100x100
316 crop=100:100
317
318 # crop the central input area with size 2/3 of the input video
319 "crop=2/3*in_w:2/3*in_h"
320
321 # crop the input video central square
322 crop=in_h
323
324 # delimit the rectangle with the top-left corner placed at position
325 # 100:100 and the right-bottom corner corresponding to the right-bottom
326 # corner of the input image.
327 crop=in_w-100:in_h-100:100:100
328
329 # crop 10 pixels from the left and right borders, and 20 pixels from
330 # the top and bottom borders
331 "crop=in_w-2*10:in_h-2*20"
332
333 # keep only the bottom right quarter of the input image
334 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
335
336 # crop height for getting Greek harmony
337 "crop=in_w:1/PHI*in_w"
338
339 # trembling effect
340 "crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)"
341
342 # erratic camera effect depending on timestamp
343 "crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
344
345 # set x depending on the value of y
346 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
347 @end example
348
349 @section cropdetect
350
351 Auto-detect crop size.
352
353 Calculate necessary cropping parameters and prints the recommended
354 parameters through the logging system. The detected dimensions
355 correspond to the non-black area of the input video.
356
357 It accepts the syntax:
358 @example
359 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
360 @end example
361
362 @table @option
363
364 @item limit
365 Threshold, which can be optionally specified from nothing (0) to
366 everything (255), defaults to 24.
367
368 @item round
369 Value which the width/height should be divisible by, defaults to
370 16. The offset is automatically adjusted to center the video. Use 2 to
371 get only even dimensions (needed for 4:2:2 video). 16 is best when
372 encoding to most video codecs.
373
374 @item reset
375 Counter that determines after how many frames cropdetect will reset
376 the previously detected largest video area and start over to detect
377 the current optimal crop area. Defaults to 0.
378
379 This can be useful when channel logos distort the video area. 0
380 indicates never reset and return the largest area encountered during
381 playback.
382 @end table
383
384 @section drawbox
385
386 Draw a colored box on the input image.
387
388 It accepts the syntax:
389 @example
390 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
391 @end example
392
393 @table @option
394
395 @item x, y
396 Specify the top left corner coordinates of the box. Default to 0.
397
398 @item width, height
399 Specify the width and height of the box, if 0 they are interpreted as
400 the input width and height. Default to 0.
401
402 @item color
403 Specify the color of the box to write, it can be the name of a color
404 (case insensitive match) or a 0xRRGGBB[AA] sequence.
405 @end table
406
407 Follow some examples:
408 @example
409 # draw a black box around the edge of the input image
410 drawbox
411
412 # draw a box with color red and an opacity of 50%
413 drawbox=10:20:200:60:red@@0.5"
414 @end example
415
416 @section drawtext
417
418 Draw text string or text from specified file on top of video using the
419 libfreetype library.
420
421 To enable compilation of this filter you need to configure FFmpeg with
422 @code{--enable-libfreetype}.
423
424 The filter also recognizes strftime() sequences in the provided text
425 and expands them accordingly. Check the documentation of strftime().
426
427 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
428 separated by ":".
429
430 The description of the accepted parameters follows.
431
432 @table @option
433
434 @item fontfile
435 The font file to be used for drawing text. Path must be included.
436 This parameter is mandatory.
437
438 @item text
439 The text string to be drawn. The text must be a sequence of UTF-8
440 encoded characters.
441 This parameter is mandatory if no file is specified with the parameter
442 @var{textfile}.
443
444 @item textfile
445 A text file containing text to be drawn. The text must be a sequence
446 of UTF-8 encoded characters.
447
448 This parameter is mandatory if no text string is specified with the
449 parameter @var{text}.
450
451 If both text and textfile are specified, an error is thrown.
452
453 @item x, y
454 The offsets where text will be drawn within the video frame.
455 Relative to the top/left border of the output image.
456
457 The default value of @var{x} and @var{y} is 0.
458
459 @item fontsize
460 The font size to be used for drawing text.
461 The default value of @var{fontsize} is 16.
462
463 @item fontcolor
464 The color to be used for drawing fonts.
465 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
466 (e.g. "0xff000033"), possibly followed by an alpha specifier.
467 The default value of @var{fontcolor} is "black".
468
469 @item boxcolor
470 The color to be used for drawing box around text.
471 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
472 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
473 The default value of @var{boxcolor} is "white".
474
475 @item box
476 Used to draw a box around text using background color.
477 Value should be either 1 (enable) or 0 (disable).
478 The default value of @var{box} is 0.
479
480 @item shadowx, shadowy
481 The x and y offsets for the text shadow position with respect to the
482 position of the text. They can be either positive or negative
483 values. Default value for both is "0".
484
485 @item shadowcolor
486 The color to be used for drawing a shadow behind the drawn text. It
487 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
488 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
489 The default value of @var{shadowcolor} is "black".
490
491 @item ft_load_flags
492 Flags to be used for loading the fonts.
493
494 The flags map the corresponding flags supported by libfreetype, and are
495 a combination of the following values:
496 @table @var
497 @item default
498 @item no_scale
499 @item no_hinting
500 @item render
501 @item no_bitmap
502 @item vertical_layout
503 @item force_autohint
504 @item crop_bitmap
505 @item pedantic
506 @item ignore_global_advance_width
507 @item no_recurse
508 @item ignore_transform
509 @item monochrome
510 @item linear_design
511 @item no_autohint
512 @item end table
513 @end table
514
515 Default value is "render".
516
517 For more information consult the documentation for the FT_LOAD_*
518 libfreetype flags.
519
520 @item tabsize
521 The size in number of spaces to use for rendering the tab.
522 Default value is 4.
523 @end table
524
525 For example the command:
526 @example
527 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
528 @end example
529
530 will draw "Test Text" with font FreeSerif, using the default values
531 for the optional parameters.
532
533 The command:
534 @example
535 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
536 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
537 @end example
538
539 will draw 'Test Text' with font FreeSerif of size 24 at position x=100
540 and y=50 (counting from the top-left corner of the screen), text is
541 yellow with a red box around it. Both the text and the box have an
542 opacity of 20%.
543
544 Note that the double quotes are not necessary if spaces are not used
545 within the parameter list.
546
547 For more information about libfreetype, check:
548 @url{http://www.freetype.org/}.
549
550 @section fade
551
552 Apply fade-in/out effect to input video.
553
554 It accepts the parameters:
555 @var{type}:@var{start_frame}:@var{nb_frames}
556
557 @var{type} specifies if the effect type, can be either "in" for
558 fade-in, or "out" for a fade-out effect.
559
560 @var{start_frame} specifies the number of the start frame for starting
561 to apply the fade effect.
562
563 @var{nb_frames} specifies the number of frames for which the fade
564 effect has to last. At the end of the fade-in effect the output video
565 will have the same intensity as the input video, at the end of the
566 fade-out transition the output video will be completely black.
567
568 A few usage examples follow, usable too as test scenarios.
569 @example
570 # fade in first 30 frames of video
571 fade=in:0:30
572
573 # fade out last 45 frames of a 200-frame video
574 fade=out:155:45
575
576 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
577 fade=in:0:25, fade=out:975:25
578
579 # make first 5 frames black, then fade in from frame 5-24
580 fade=in:5:20
581 @end example
582
583 @section fieldorder
584
585 Transform the field order of the input video.
586
587 It accepts one parameter which specifies the required field order that
588 the input interlaced video will be transformed to. The parameter can
589 assume one of the following values:
590
591 @table @option
592 @item 0 or bff
593 output bottom field first
594 @item 1 or tff
595 output top field first
596 @end table
597
598 Default value is "tff".
599
600 Transformation is achieved by shifting the picture content up or down
601 by one line, and filling the remaining line with appropriate picture content.
602 This method is consistent with most broadcast field order converters.
603
604 If the input video is not flagged as being interlaced, or it is already
605 flagged as being of the required output field order then this filter does
606 not alter the incoming video.
607
608 This filter is very useful when converting to or from PAL DV material,
609 which is bottom field first.
610
611 For example:
612 @example
613 ./ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
614 @end example
615
616 @section fifo
617
618 Buffer input images and send them when they are requested.
619
620 This filter is mainly useful when auto-inserted by the libavfilter
621 framework.
622
623 The filter does not take parameters.
624
625 @section format
626
627 Convert the input video to one of the specified pixel formats.
628 Libavfilter will try to pick one that is supported for the input to
629 the next filter.
630
631 The filter accepts a list of pixel format names, separated by ":",
632 for example "yuv420p:monow:rgb24".
633
634 Some examples follow:
635 @example
636 # convert the input video to the format "yuv420p"
637 format=yuv420p
638
639 # convert the input video to any of the formats in the list
640 format=yuv420p:yuv444p:yuv410p
641 @end example
642
643 @anchor{frei0r}
644 @section frei0r
645
646 Apply a frei0r effect to the input video.
647
648 To enable compilation of this filter you need to install the frei0r
649 header and configure Libav with --enable-frei0r.
650
651 The filter supports the syntax:
652 @example
653 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
654 @end example
655
656 @var{filter_name} is the name to the frei0r effect to load. If the
657 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
658 is searched in each one of the directories specified by the colon
659 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
660 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
661 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
662
663 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
664 for the frei0r effect.
665
666 A frei0r effect parameter can be a boolean (whose values are specified
667 with "y" and "n"), a double, a color (specified by the syntax
668 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
669 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
670 description), a position (specified by the syntax @var{X}/@var{Y},
671 @var{X} and @var{Y} being float numbers) and a string.
672
673 The number and kind of parameters depend on the loaded effect. If an
674 effect parameter is not specified the default value is set.
675
676 Some examples follow:
677 @example
678 # apply the distort0r effect, set the first two double parameters
679 frei0r=distort0r:0.5:0.01
680
681 # apply the colordistance effect, takes a color as first parameter
682 frei0r=colordistance:0.2/0.3/0.4
683 frei0r=colordistance:violet
684 frei0r=colordistance:0x112233
685
686 # apply the perspective effect, specify the top left and top right
687 # image positions
688 frei0r=perspective:0.2/0.2:0.8/0.2
689 @end example
690
691 For more information see:
692 @url{http://piksel.org/frei0r}
693
694 @section gradfun
695
696 Fix the banding artifacts that are sometimes introduced into nearly flat
697 regions by truncation to 8bit colordepth.
698 Interpolate the gradients that should go where the bands are, and
699 dither them.
700
701 This filter is designed for playback only. Do not use it prior to
702 lossy compression, because compression tends to lose the dither and
703 bring back the bands.
704
705 The filter takes two optional parameters, separated by ':':
706 @var{strength}:@var{radius}
707
708 @var{strength} is the maximum amount by which the filter will change
709 any one pixel. Also the threshold for detecting nearly flat
710 regions. Acceptable values range from .51 to 255, default value is
711 1.2, out-of-range values will be clipped to the valid range.
712
713 @var{radius} is the neighborhood to fit the gradient to. A larger
714 radius makes for smoother gradients, but also prevents the filter from
715 modifying the pixels near detailed regions. Acceptable values are
716 8-32, default value is 16, out-of-range values will be clipped to the
717 valid range.
718
719 @example
720 # default parameters
721 gradfun=1.2:16
722
723 # omitting radius
724 gradfun=1.2
725 @end example
726
727 @section hflip
728
729 Flip the input video horizontally.
730
731 For example to horizontally flip the video in input with
732 @file{ffmpeg}:
733 @example
734 ffmpeg -i in.avi -vf "hflip" out.avi
735 @end example
736
737 @section hqdn3d
738
739 High precision/quality 3d denoise filter. This filter aims to reduce
740 image noise producing smooth images and making still images really
741 still. It should enhance compressibility.
742
743 It accepts the following optional parameters:
744 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
745
746 @table @option
747 @item luma_spatial
748 a non-negative float number which specifies spatial luma strength,
749 defaults to 4.0
750
751 @item chroma_spatial
752 a non-negative float number which specifies spatial chroma strength,
753 defaults to 3.0*@var{luma_spatial}/4.0
754
755 @item luma_tmp
756 a float number which specifies luma temporal strength, defaults to
757 6.0*@var{luma_spatial}/4.0
758
759 @item chroma_tmp
760 a float number which specifies chroma temporal strength, defaults to
761 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
762 @end table
763
764 @section lut, lutrgb, lutyuv
765
766 Compute a look-up table for binding each pixel component input value
767 to an output value, and apply it to input video.
768
769 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
770 to an RGB input video.
771
772 These filters accept in input a ":"-separated list of options, which
773 specify the expressions used for computing the lookup table for the
774 corresponding pixel component values.
775
776 The @var{lut} filter requires either YUV or RGB pixel formats in
777 input, and accepts the options:
778 @table @option
779 @var{c0} (first pixel component)
780 @var{c1} (second pixel component)
781 @var{c2} (third pixel component)
782 @var{c3} (fourth pixel component, corresponds to the alpha component)
783 @end table
784
785 The exact component associated to each option depends on the format in
786 input.
787
788 The @var{lutrgb} filter requires RGB pixel formats in input, and
789 accepts the options:
790 @table @option
791 @var{r} (red component)
792 @var{g} (green component)
793 @var{b} (blue component)
794 @var{a} (alpha component)
795 @end table
796
797 The @var{lutyuv} filter requires YUV pixel formats in input, and
798 accepts the options:
799 @table @option
800 @var{y} (Y/luminance component)
801 @var{u} (U/Cb component)
802 @var{v} (V/Cr component)
803 @var{a} (alpha component)
804 @end table
805
806 The expressions can contain the following constants and functions:
807
808 @table @option
809 @item E, PI, PHI
810 the corresponding mathematical approximated values for e
811 (euler number), pi (greek PI), PHI (golden ratio)
812
813 @item w, h
814 the input width and heigth
815
816 @item val
817 input value for the pixel component
818
819 @item clipval
820 the input value clipped in the @var{minval}-@var{maxval} range
821
822 @item maxval
823 maximum value for the pixel component
824
825 @item minval
826 minimum value for the pixel component
827
828 @item negval
829 the negated value for the pixel component value clipped in the
830 @var{minval}-@var{maxval} range , it corresponds to the expression
831 "maxval-clipval+minval"
832
833 @item clip(val)
834 the computed value in @var{val} clipped in the
835 @var{minval}-@var{maxval} range
836
837 @item gammaval(gamma)
838 the computed gamma correction value of the pixel component value
839 clipped in the @var{minval}-@var{maxval} range, corresponds to the
840 expression
841 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
842
843 @end table
844
845 All expressions default to "val".
846
847 Some examples follow:
848 @example
849 # negate input video
850 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
851 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
852
853 # the above is the same as
854 lutrgb="r=negval:g=negval:b=negval"
855 lutyuv="y=negval:u=negval:v=negval"
856
857 # negate luminance
858 lutyuv=negval
859
860 # remove chroma components, turns the video into a graytone image
861 lutyuv="u=128:v=128"
862
863 # apply a luma burning effect
864 lutyuv="y=2*val"
865
866 # remove green and blue components
867 lutrgb="g=0:b=0"
868
869 # set a constant alpha channel value on input
870 format=rgba,lutrgb=a="maxval-minval/2"
871
872 # correct luminance gamma by a 0.5 factor
873 lutyuv=y=gammaval(0.5)
874 @end example
875
876 @section negate
877
878 Negate input video.
879
880 This filter accepts an integer in input, if non-zero it negates the
881 alpha component (if available). The default value in input is 0.
882
883 Force libavfilter not to use any of the specified pixel formats for the
884 input to the next filter.
885
886 The filter accepts a list of pixel format names, separated by ":",
887 for example "yuv420p:monow:rgb24".
888
889 Some examples follow:
890 @example
891 # force libavfilter to use a format different from "yuv420p" for the
892 # input to the vflip filter
893 noformat=yuv420p,vflip
894
895 # convert the input video to any of the formats not contained in the list
896 noformat=yuv420p:yuv444p:yuv410p
897 @end example
898
899 @section null
900
901 Pass the video source unchanged to the output.
902
903 @section ocv
904
905 Apply video transform using libopencv.
906
907 To enable this filter install libopencv library and headers and
908 configure Libav with --enable-libopencv.
909
910 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
911
912 @var{filter_name} is the name of the libopencv filter to apply.
913
914 @var{filter_params} specifies the parameters to pass to the libopencv
915 filter. If not specified the default values are assumed.
916
917 Refer to the official libopencv documentation for more precise
918 informations:
919 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
920
921 Follows the list of supported libopencv filters.
922
923 @anchor{dilate}
924 @subsection dilate
925
926 Dilate an image by using a specific structuring element.
927 This filter corresponds to the libopencv function @code{cvDilate}.
928
929 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
930
931 @var{struct_el} represents a structuring element, and has the syntax:
932 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
933
934 @var{cols} and @var{rows} represent the number of colums and rows of
935 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
936 point, and @var{shape} the shape for the structuring element, and
937 can be one of the values "rect", "cross", "ellipse", "custom".
938
939 If the value for @var{shape} is "custom", it must be followed by a
940 string of the form "=@var{filename}". The file with name
941 @var{filename} is assumed to represent a binary image, with each
942 printable character corresponding to a bright pixel. When a custom
943 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
944 or columns and rows of the read file are assumed instead.
945
946 The default value for @var{struct_el} is "3x3+0x0/rect".
947
948 @var{nb_iterations} specifies the number of times the transform is
949 applied to the image, and defaults to 1.
950
951 Follow some example:
952 @example
953 # use the default values
954 ocv=dilate
955
956 # dilate using a structuring element with a 5x5 cross, iterate two times
957 ocv=dilate=5x5+2x2/cross:2
958
959 # read the shape from the file diamond.shape, iterate two times
960 # the file diamond.shape may contain a pattern of characters like this:
961 # *
962 # ***
963 # *****
964 # ***
965 # *
966 # the specified cols and rows are ignored (but not the anchor point coordinates)
967 ocv=0x0+2x2/custom=diamond.shape:2
968 @end example
969
970 @subsection erode
971
972 Erode an image by using a specific structuring element.
973 This filter corresponds to the libopencv function @code{cvErode}.
974
975 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
976 with the same syntax and semantics as the @ref{dilate} filter.
977
978 @subsection smooth
979
980 Smooth the input video.
981
982 The filter takes the following parameters:
983 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
984
985 @var{type} is the type of smooth filter to apply, and can be one of
986 the following values: "blur", "blur_no_scale", "median", "gaussian",
987 "bilateral". The default value is "gaussian".
988
989 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
990 parameters whose meanings depend on smooth type. @var{param1} and
991 @var{param2} accept integer positive values or 0, @var{param3} and
992 @var{param4} accept float values.
993
994 The default value for @var{param1} is 3, the default value for the
995 other parameters is 0.
996
997 These parameters correspond to the parameters assigned to the
998 libopencv function @code{cvSmooth}.
999
1000 @section overlay
1001
1002 Overlay one video on top of another.
1003
1004 It takes two inputs and one output, the first input is the "main"
1005 video on which the second input is overlayed.
1006
1007 It accepts the parameters: @var{x}:@var{y}.
1008
1009 @var{x} is the x coordinate of the overlayed video on the main video,
1010 @var{y} is the y coordinate. The parameters are expressions containing
1011 the following parameters:
1012
1013 @table @option
1014 @item main_w, main_h
1015 main input width and height
1016
1017 @item W, H
1018 same as @var{main_w} and @var{main_h}
1019
1020 @item overlay_w, overlay_h
1021 overlay input width and height
1022
1023 @item w, h
1024 same as @var{overlay_w} and @var{overlay_h}
1025 @end table
1026
1027 Be aware that frames are taken from each input video in timestamp
1028 order, hence, if their initial timestamps differ, it is a a good idea
1029 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1030 have them begin in the same zero timestamp, as it does the example for
1031 the @var{movie} filter.
1032
1033 Follow some examples:
1034 @example
1035 # draw the overlay at 10 pixels from the bottom right
1036 # corner of the main video.
1037 overlay=main_w-overlay_w-10:main_h-overlay_h-10
1038
1039 # insert a transparent PNG logo in the bottom left corner of the input
1040 movie=logo.png [logo];
1041 [in][logo] overlay=10:main_h-overlay_h-10 [out]
1042
1043 # insert 2 different transparent PNG logos (second logo on bottom
1044 # right corner):
1045 movie=logo1.png [logo1];
1046 movie=logo2.png [logo2];
1047 [in][logo1] overlay=10:H-h-10 [in+logo1];
1048 [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
1049
1050 # add a transparent color layer on top of the main video,
1051 # WxH specifies the size of the main input to the overlay filter
1052 color=red@.3:WxH [over]; [in][over] overlay [out]
1053 @end example
1054
1055 You can chain togheter more overlays but the efficiency of such
1056 approach is yet to be tested.
1057
1058 @section pad
1059
1060 Add paddings to the input image, and places the original input at the
1061 given coordinates @var{x}, @var{y}.
1062
1063 It accepts the following parameters:
1064 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1065
1066 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1067 expressions containing the following constants:
1068
1069 @table @option
1070 @item E, PI, PHI
1071 the corresponding mathematical approximated values for e
1072 (euler number), pi (greek PI), phi (golden ratio)
1073
1074 @item in_w, in_h
1075 the input video width and height
1076
1077 @item iw, ih
1078 same as @var{in_w} and @var{in_h}
1079
1080 @item out_w, out_h
1081 the output width and height, that is the size of the padded area as
1082 specified by the @var{width} and @var{height} expressions
1083
1084 @item ow, oh
1085 same as @var{out_w} and @var{out_h}
1086
1087 @item x, y
1088 x and y offsets as specified by the @var{x} and @var{y}
1089 expressions, or NAN if not yet specified
1090
1091 @item a
1092 input display aspect ratio, same as @var{iw} / @var{ih}
1093
1094 @item hsub, vsub
1095 horizontal and vertical chroma subsample values. For example for the
1096 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1097 @end table
1098
1099 Follows the description of the accepted parameters.
1100
1101 @table @option
1102 @item width, height
1103
1104 Specify the size of the output image with the paddings added. If the
1105 value for @var{width} or @var{height} is 0, the corresponding input size
1106 is used for the output.
1107
1108 The @var{width} expression can reference the value set by the
1109 @var{height} expression, and viceversa.
1110
1111 The default value of @var{width} and @var{height} is 0.
1112
1113 @item x, y
1114
1115 Specify the offsets where to place the input image in the padded area
1116 with respect to the top/left border of the output image.
1117
1118 The @var{x} expression can reference the value set by the @var{y}
1119 expression, and viceversa.
1120
1121 The default value of @var{x} and @var{y} is 0.
1122
1123 @item color
1124
1125 Specify the color of the padded area, it can be the name of a color
1126 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1127
1128 The default value of @var{color} is "black".
1129
1130 @end table
1131
1132 Some examples follow:
1133
1134 @example
1135 # Add paddings with color "violet" to the input video. Output video
1136 # size is 640x480, the top-left corner of the input video is placed at
1137 # column 0, row 40.
1138 pad=640:480:0:40:violet
1139
1140 # pad the input to get an output with dimensions increased bt 3/2,
1141 # and put the input video at the center of the padded area
1142 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1143
1144 # pad the input to get a squared output with size equal to the maximum
1145 # value between the input width and height, and put the input video at
1146 # the center of the padded area
1147 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1148
1149 # pad the input to get a final w/h ratio of 16:9
1150 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1151
1152 # double output size and put the input video in the bottom-right
1153 # corner of the output padded area
1154 pad="2*iw:2*ih:ow-iw:oh-ih"
1155 @end example
1156
1157 @section pixdesctest
1158
1159 Pixel format descriptor test filter, mainly useful for internal
1160 testing. The output video should be equal to the input video.
1161
1162 For example:
1163 @example
1164 format=monow, pixdesctest
1165 @end example
1166
1167 can be used to test the monowhite pixel format descriptor definition.
1168
1169 @section scale
1170
1171 Scale the input video to @var{width}:@var{height} and/or convert the image format.
1172
1173 The parameters @var{width} and @var{height} are expressions containing
1174 the following constants:
1175
1176 @table @option
1177 @item E, PI, PHI
1178 the corresponding mathematical approximated values for e
1179 (euler number), pi (greek PI), phi (golden ratio)
1180
1181 @item in_w, in_h
1182 the input width and height
1183
1184 @item iw, ih
1185 same as @var{in_w} and @var{in_h}
1186
1187 @item out_w, out_h
1188 the output (cropped) width and height
1189
1190 @item ow, oh
1191 same as @var{out_w} and @var{out_h}
1192
1193 @item dar, a
1194 input display aspect ratio, same as @var{iw} / @var{ih}
1195
1196 @item sar
1197 input sample aspect ratio
1198
1199 @item hsub, vsub
1200 horizontal and vertical chroma subsample values. For example for the
1201 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1202 @end table
1203
1204 If the input image format is different from the format requested by
1205 the next filter, the scale filter will convert the input to the
1206 requested format.
1207
1208 If the value for @var{width} or @var{height} is 0, the respective input
1209 size is used for the output.
1210
1211 If the value for @var{width} or @var{height} is -1, the scale filter will
1212 use, for the respective output size, a value that maintains the aspect
1213 ratio of the input image.
1214
1215 The default value of @var{width} and @var{height} is 0.
1216
1217 Some examples follow:
1218 @example
1219 # scale the input video to a size of 200x100.
1220 scale=200:100
1221
1222 # scale the input to 2x
1223 scale=2*iw:2*ih
1224 # the above is the same as
1225 scale=2*in_w:2*in_h
1226
1227 # scale the input to half size
1228 scale=iw/2:ih/2
1229
1230 # increase the width, and set the height to the same size
1231 scale=3/2*iw:ow
1232
1233 # seek for Greek harmony
1234 scale=iw:1/PHI*iw
1235 scale=ih*PHI:ih
1236
1237 # increase the height, and set the width to 3/2 of the height
1238 scale=3/2*oh:3/5*ih
1239
1240 # increase the size, but make the size a multiple of the chroma
1241 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1242
1243 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1244 scale='min(500\, iw*3/2):-1'
1245 @end example
1246
1247 @section select
1248 Select frames to pass in output.
1249
1250 It accepts in input an expression, which is evaluated for each input
1251 frame. If the expression is evaluated to a non-zero value, the frame
1252 is selected and passed to the output, otherwise it is discarded.
1253
1254 The expression can contain the following constants:
1255
1256 @table @option
1257 @item PI
1258 Greek PI
1259
1260 @item PHI
1261 golden ratio
1262
1263 @item E
1264 Euler number
1265
1266 @item n
1267 the sequential number of the filtered frame, starting from 0
1268
1269 @item selected_n
1270 the sequential number of the selected frame, starting from 0
1271
1272 @item prev_selected_n
1273 the sequential number of the last selected frame, NAN if undefined
1274
1275 @item TB
1276 timebase of the input timestamps
1277
1278 @item pts
1279 the PTS (Presentation TimeStamp) of the filtered video frame,
1280 expressed in @var{TB} units, NAN if undefined
1281
1282 @item t
1283 the PTS (Presentation TimeStamp) of the filtered video frame,
1284 expressed in seconds, NAN if undefined
1285
1286 @item prev_pts
1287 the PTS of the previously filtered video frame, NAN if undefined
1288
1289 @item prev_selected_pts
1290 the PTS of the last previously filtered video frame, NAN if undefined
1291
1292 @item prev_selected_t
1293 the PTS of the last previously selected video frame, NAN if undefined
1294
1295 @item start_pts
1296 the PTS of the first video frame in the video, NAN if undefined
1297
1298 @item start_t
1299 the time of the first video frame in the video, NAN if undefined
1300
1301 @item pict_type
1302 the type of the filtered frame, can assume one of the following
1303 values:
1304 @table @option
1305 @item I
1306 @item P
1307 @item B
1308 @item S
1309 @item SI
1310 @item SP
1311 @item BI
1312 @end table
1313
1314 @item interlace_type
1315 the frame interlace type, can assume one of the following values:
1316 @table @option
1317 @item PROGRESSIVE
1318 the frame is progressive (not interlaced)
1319 @item TOPFIRST
1320 the frame is top-field-first
1321 @item BOTTOMFIRST
1322 the frame is bottom-field-first
1323 @end table
1324
1325 @item key
1326 1 if the filtered frame is a key-frame, 0 otherwise
1327
1328 @item pos
1329 the position in the file of the filtered frame, -1 if the information
1330 is not available (e.g. for synthetic video)
1331 @end table
1332
1333 The default value of the select expression is "1".
1334
1335 Some examples follow:
1336
1337 @example
1338 # select all frames in input
1339 select
1340
1341 # the above is the same as:
1342 select=1
1343
1344 # skip all frames:
1345 select=0
1346
1347 # select only I-frames
1348 select='eq(pict_type\,I)'
1349
1350 # select one frame every 100
1351 select='not(mod(n\,100))'
1352
1353 # select only frames contained in the 10-20 time interval
1354 select='gte(t\,10)*lte(t\,20)'
1355
1356 # select only I frames contained in the 10-20 time interval
1357 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
1358
1359 # select frames with a minimum distance of 10 seconds
1360 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
1361 @end example
1362
1363 @anchor{setdar}
1364 @section setdar
1365
1366 Set the Display Aspect Ratio for the filter output video.
1367
1368 This is done by changing the specified Sample (aka Pixel) Aspect
1369 Ratio, according to the following equation:
1370 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1371
1372 Keep in mind that this filter does not modify the pixel dimensions of
1373 the video frame. Also the display aspect ratio set by this filter may
1374 be changed by later filters in the filterchain, e.g. in case of
1375 scaling or if another "setdar" or a "setsar" filter is applied.
1376
1377 The filter accepts a parameter string which represents the wanted
1378 display aspect ratio.
1379 The parameter can be a floating point number string, or an expression
1380 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1381 numerator and denominator of the aspect ratio.
1382 If the parameter is not specified, it is assumed the value "0:1".
1383
1384 For example to change the display aspect ratio to 16:9, specify:
1385 @example
1386 setdar=16:9
1387 # the above is equivalent to
1388 setdar=1.77777
1389 @end example
1390
1391 See also the @ref{setsar} filter documentation.
1392
1393 @section setpts
1394
1395 Change the PTS (presentation timestamp) of the input video frames.
1396
1397 Accept in input an expression evaluated through the eval API, which
1398 can contain the following constants:
1399
1400 @table @option
1401 @item PTS
1402 the presentation timestamp in input
1403
1404 @item PI
1405 Greek PI
1406
1407 @item PHI
1408 golden ratio
1409
1410 @item E
1411 Euler number
1412
1413 @item N
1414 the count of the input frame, starting from 0.
1415
1416 @item STARTPTS
1417 the PTS of the first video frame
1418
1419 @item INTERLACED
1420 tell if the current frame is interlaced
1421
1422 @item POS
1423 original position in the file of the frame, or undefined if undefined
1424 for the current frame
1425
1426 @item PREV_INPTS
1427 previous input PTS
1428
1429 @item PREV_OUTPTS
1430 previous output PTS
1431
1432 @end table
1433
1434 Some examples follow:
1435
1436 @example
1437 # start counting PTS from zero
1438 setpts=PTS-STARTPTS
1439
1440 # fast motion
1441 setpts=0.5*PTS
1442
1443 # slow motion
1444 setpts=2.0*PTS
1445
1446 # fixed rate 25 fps
1447 setpts=N/(25*TB)
1448
1449 # fixed rate 25 fps with some jitter
1450 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1451 @end example
1452
1453 @anchor{setsar}
1454 @section setsar
1455
1456 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1457
1458 Note that as a consequence of the application of this filter, the
1459 output display aspect ratio will change according to the following
1460 equation:
1461 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1462
1463 Keep in mind that the sample aspect ratio set by this filter may be
1464 changed by later filters in the filterchain, e.g. if another "setsar"
1465 or a "setdar" filter is applied.
1466
1467 The filter accepts a parameter string which represents the wanted
1468 sample aspect ratio.
1469 The parameter can be a floating point number string, or an expression
1470 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1471 numerator and denominator of the aspect ratio.
1472 If the parameter is not specified, it is assumed the value "0:1".
1473
1474 For example to change the sample aspect ratio to 10:11, specify:
1475 @example
1476 setsar=10:11
1477 @end example
1478
1479 @section settb
1480
1481 Set the timebase to use for the output frames timestamps.
1482 It is mainly useful for testing timebase configuration.
1483
1484 It accepts in input an arithmetic expression representing a rational.
1485 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1486 default timebase), and "intb" (the input timebase).
1487
1488 The default value for the input is "intb".
1489
1490 Follow some examples.
1491
1492 @example
1493 # set the timebase to 1/25
1494 settb=1/25
1495
1496 # set the timebase to 1/10
1497 settb=0.1
1498
1499 #set the timebase to 1001/1000
1500 settb=1+0.001
1501
1502 #set the timebase to 2*intb
1503 settb=2*intb
1504
1505 #set the default timebase value
1506 settb=AVTB
1507 @end example
1508
1509 @section showinfo
1510
1511 Show a line containing various information for each input video frame.
1512 The input video is not modified.
1513
1514 The shown line contains a sequence of key/value pairs of the form
1515 @var{key}:@var{value}.
1516
1517 A description of each shown parameter follows:
1518
1519 @table @option
1520 @item n
1521 sequential number of the input frame, starting from 0
1522
1523 @item pts
1524 Presentation TimeStamp of the input frame, expressed as a number of
1525 time base units. The time base unit depends on the filter input pad.
1526
1527 @item pts_time
1528 Presentation TimeStamp of the input frame, expressed as a number of
1529 seconds
1530
1531 @item pos
1532 position of the frame in the input stream, -1 if this information in
1533 unavailable and/or meanigless (for example in case of synthetic video)
1534
1535 @item fmt
1536 pixel format name
1537
1538 @item sar
1539 sample aspect ratio of the input frame, expressed in the form
1540 @var{num}/@var{den}
1541
1542 @item s
1543 size of the input frame, expressed in the form
1544 @var{width}x@var{height}
1545
1546 @item i
1547 interlaced mode ("P" for "progressive", "T" for top field first, "B"
1548 for bottom field first)
1549
1550 @item iskey
1551 1 if the frame is a key frame, 0 otherwise
1552
1553 @item type
1554 picture type of the input frame ("I" for an I-frame, "P" for a
1555 P-frame, "B" for a B-frame, "?" for unknown type).
1556 Check also the documentation of the @code{AVPictureType} enum and of
1557 the @code{av_get_picture_type_char} function defined in
1558 @file{libavutil/avutil.h}.
1559
1560 @item checksum
1561 Adler-32 checksum of all the planes of the input frame
1562
1563 @item plane_checksum
1564 Adler-32 checksum of each plane of the input frame, expressed in the form
1565 "[@var{c0} @var{c1} @var{c2} @var{c3}]"
1566 @end table
1567
1568 @section slicify
1569
1570 Pass the images of input video on to next video filter as multiple
1571 slices.
1572
1573 @example
1574 ./ffmpeg -i in.avi -vf "slicify=32" out.avi
1575 @end example
1576
1577 The filter accepts the slice height as parameter. If the parameter is
1578 not specified it will use the default value of 16.
1579
1580 Adding this in the beginning of filter chains should make filtering
1581 faster due to better use of the memory cache.
1582
1583 @section transpose
1584
1585 Transpose rows with columns in the input video and optionally flip it.
1586
1587 It accepts a parameter representing an integer, which can assume the
1588 values:
1589
1590 @table @samp
1591 @item 0
1592 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1593 @example
1594 L.R L.l
1595 . . -> . .
1596 l.r R.r
1597 @end example
1598
1599 @item 1
1600 Rotate by 90 degrees clockwise, that is:
1601 @example
1602 L.R l.L
1603 . . -> . .
1604 l.r r.R
1605 @end example
1606
1607 @item 2
1608 Rotate by 90 degrees counterclockwise, that is:
1609 @example
1610 L.R R.r
1611 . . -> . .
1612 l.r L.l
1613 @end example
1614
1615 @item 3
1616 Rotate by 90 degrees clockwise and vertically flip, that is:
1617 @example
1618 L.R r.R
1619 . . -> . .
1620 l.r l.L
1621 @end example
1622 @end table
1623
1624 @section unsharp
1625
1626 Sharpen or blur the input video.
1627
1628 It accepts the following parameters:
1629 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1630
1631 Negative values for the amount will blur the input video, while positive
1632 values will sharpen. All parameters are optional and default to the
1633 equivalent of the string '5:5:1.0:5:5:0.0'.
1634
1635 @table @option
1636
1637 @item luma_msize_x
1638 Set the luma matrix horizontal size. It can be an integer between 3
1639 and 13, default value is 5.
1640
1641 @item luma_msize_y
1642 Set the luma matrix vertical size. It can be an integer between 3
1643 and 13, default value is 5.
1644
1645 @item luma_amount
1646 Set the luma effect strength. It can be a float number between -2.0
1647 and 5.0, default value is 1.0.
1648
1649 @item chroma_msize_x
1650 Set the chroma matrix horizontal size. It can be an integer between 3
1651 and 13, default value is 5.
1652
1653 @item chroma_msize_y
1654 Set the chroma matrix vertical size. It can be an integer between 3
1655 and 13, default value is 5.
1656
1657 @item luma_amount
1658 Set the chroma effect strength. It can be a float number between -2.0
1659 and 5.0, default value is 0.0.
1660
1661 @end table
1662
1663 @example
1664 # Strong luma sharpen effect parameters
1665 unsharp=7:7:2.5
1666
1667 # Strong blur of both luma and chroma parameters
1668 unsharp=7:7:-2:7:7:-2
1669
1670 # Use the default values with @command{ffmpeg}
1671 ./ffmpeg -i in.avi -vf "unsharp" out.mp4
1672 @end example
1673
1674 @section vflip
1675
1676 Flip the input video vertically.
1677
1678 @example
1679 ./ffmpeg -i in.avi -vf "vflip" out.avi
1680 @end example
1681
1682 @section yadif
1683
1684 Deinterlace the input video ("yadif" means "yet another deinterlacing
1685 filter").
1686
1687 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
1688
1689 @var{mode} specifies the interlacing mode to adopt, accepts one of the
1690 following values:
1691
1692 @table @option
1693 @item 0
1694 output 1 frame for each frame
1695 @item 1
1696 output 1 frame for each field
1697 @item 2
1698 like 0 but skips spatial interlacing check
1699 @item 3
1700 like 1 but skips spatial interlacing check
1701 @end table
1702
1703 Default value is 0.
1704
1705 @var{parity} specifies the picture field parity assumed for the input
1706 interlaced video, accepts one of the following values:
1707
1708 @table @option
1709 @item 0
1710 assume top field first
1711 @item 1
1712 assume bottom field first
1713 @item -1
1714 enable automatic detection
1715 @end table
1716
1717 Default value is -1.
1718 If interlacing is unknown or decoder does not export this information,
1719 top field first will be assumed.
1720
1721 @var{auto] specifies if deinterlacer should trust the interlaced flag
1722 and only deinterlace frames marked as interlaced
1723
1724 @table @option
1725 @item 0
1726 deinterlace all frames
1727 @item 1
1728 only deinterlace frames marked as interlaced
1729 @end table
1730
1731 Default value is 0.
1732
1733 @c man end VIDEO FILTERS
1734
1735 @chapter Video Sources
1736 @c man begin VIDEO SOURCES
1737
1738 Below is a description of the currently available video sources.
1739
1740 @section buffer
1741
1742 Buffer video frames, and make them available to the filter chain.
1743
1744 This source is mainly intended for a programmatic use, in particular
1745 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1746
1747 It accepts the following parameters:
1748 @var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1749
1750 All the parameters need to be explicitely defined.
1751
1752 Follows the list of the accepted parameters.
1753
1754 @table @option
1755
1756 @item width, height
1757 Specify the width and height of the buffered video frames.
1758
1759 @item pix_fmt_string
1760 A string representing the pixel format of the buffered video frames.
1761 It may be a number corresponding to a pixel format, or a pixel format
1762 name.
1763
1764 @item timebase_num, timebase_den
1765 Specify numerator and denomitor of the timebase assumed by the
1766 timestamps of the buffered frames.
1767
1768 @item sample_aspect_ratio.num, sample_aspect_ratio.den
1769 Specify numerator and denominator of the sample aspect ratio assumed
1770 by the video frames.
1771 @end table
1772
1773 For example:
1774 @example
1775 buffer=320:240:yuv410p:1:24:1:1
1776 @end example
1777
1778 will instruct the source to accept video frames with size 320x240 and
1779 with format "yuv410p", assuming 1/24 as the timestamps timebase and
1780 square pixels (1:1 sample aspect ratio).
1781 Since the pixel format with name "yuv410p" corresponds to the number 6
1782 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1783 this example corresponds to:
1784 @example
1785 buffer=320:240:6:1:24
1786 @end example
1787
1788 @section color
1789
1790 Provide an uniformly colored input.
1791
1792 It accepts the following parameters:
1793 @var{color}:@var{frame_size}:@var{frame_rate}
1794
1795 Follows the description of the accepted parameters.
1796
1797 @table @option
1798
1799 @item color
1800 Specify the color of the source. It can be the name of a color (case
1801 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1802 alpha specifier. The default value is "black".
1803
1804 @item frame_size
1805 Specify the size of the sourced video, it may be a string of the form
1806 @var{width}x@var{height}, or the name of a size abbreviation. The
1807 default value is "320x240".
1808
1809 @item frame_rate
1810 Specify the frame rate of the sourced video, as the number of frames
1811 generated per second. It has to be a string in the format
1812 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1813 number or a valid video frame rate abbreviation. The default value is
1814 "25".
1815
1816 @end table
1817
1818 For example the following graph description will generate a red source
1819 with an opacity of 0.2, with size "qcif" and a frame rate of 10
1820 frames per second, which will be overlayed over the source connected
1821 to the pad with identifier "in".
1822
1823 @example
1824 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1825 @end example
1826
1827 @section movie
1828
1829 Read a video stream from a movie container.
1830
1831 It accepts the syntax: @var{movie_name}[:@var{options}] where
1832 @var{movie_name} is the name of the resource to read (not necessarily
1833 a file but also a device or a stream accessed through some protocol),
1834 and @var{options} is an optional sequence of @var{key}=@var{value}
1835 pairs, separated by ":".
1836
1837 The description of the accepted options follows.
1838
1839 @table @option
1840
1841 @item format_name, f
1842 Specifies the format assumed for the movie to read, and can be either
1843 the name of a container or an input device. If not specified the
1844 format is guessed from @var{movie_name} or by probing.
1845
1846 @item seek_point, sp
1847 Specifies the seek point in seconds, the frames will be output
1848 starting from this seek point, the parameter is evaluated with
1849 @code{av_strtod} so the numerical value may be suffixed by an IS
1850 postfix. Default value is "0".
1851
1852 @item stream_index, si
1853 Specifies the index of the video stream to read. If the value is -1,
1854 the best suited video stream will be automatically selected. Default
1855 value is "-1".
1856
1857 @end table
1858
1859 This filter allows to overlay a second video on top of main input of
1860 a filtergraph as shown in this graph:
1861 @example
1862 input -----------> deltapts0 --> overlay --> output
1863 ^
1864 |
1865 movie --> scale--> deltapts1 -------+
1866 @end example
1867
1868 Some examples follow:
1869 @example
1870 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1871 # on top of the input labelled as "in".
1872 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1873 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1874
1875 # read from a video4linux2 device, and overlay it on top of the input
1876 # labelled as "in"
1877 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1878 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1879
1880 @end example
1881
1882 @section nullsrc
1883
1884 Null video source, never return images. It is mainly useful as a
1885 template and to be employed in analysis / debugging tools.
1886
1887 It accepts as optional parameter a string of the form
1888 @var{width}:@var{height}:@var{timebase}.
1889
1890 @var{width} and @var{height} specify the size of the configured
1891 source. The default values of @var{width} and @var{height} are
1892 respectively 352 and 288 (corresponding to the CIF size format).
1893
1894 @var{timebase} specifies an arithmetic expression representing a
1895 timebase. The expression can contain the constants "PI", "E", "PHI",
1896 "AVTB" (the default timebase), and defaults to the value "AVTB".
1897
1898 @section frei0r_src
1899
1900 Provide a frei0r source.
1901
1902 To enable compilation of this filter you need to install the frei0r
1903 header and configure Libav with --enable-frei0r.
1904
1905 The source supports the syntax:
1906 @example
1907 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1908 @end example
1909
1910 @var{size} is the size of the video to generate, may be a string of the
1911 form @var{width}x@var{height} or a frame size abbreviation.
1912 @var{rate} is the rate of the video to generate, may be a string of
1913 the form @var{num}/@var{den} or a frame rate abbreviation.
1914 @var{src_name} is the name to the frei0r source to load. For more
1915 information regarding frei0r and how to set the parameters read the
1916 section @ref{frei0r} in the description of the video filters.
1917
1918 Some examples follow:
1919 @example
1920 # generate a frei0r partik0l source with size 200x200 and framerate 10
1921 # which is overlayed on the overlay filter main input
1922 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
1923 @end example
1924
1925 @c man end VIDEO SOURCES
1926
1927 @chapter Video Sinks
1928 @c man begin VIDEO SINKS
1929
1930 Below is a description of the currently available video sinks.
1931
1932 @section nullsink
1933
1934 Null video sink, do absolutely nothing with the input video. It is
1935 mainly useful as a template and to be employed in analysis / debugging
1936 tools.
1937
1938 @c man end VIDEO SINKS
1939