1 @chapter Filtergraph description
2 @c man begin FILTERGRAPH DESCRIPTION
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.
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.
14 A filter with no input pads is called a "source", a filter with no
15 output pads is called a "sink".
17 @anchor{Filtergraph syntax}
18 @section Filtergraph syntax
20 A filtergraph can be represented using a textual representation, which is
21 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
22 options in @command{avconv} and @option{-vf} in @command{avplay}, and by the
23 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
24 @file{libavfilter/avfiltergraph.h}.
26 A filterchain consists of a sequence of connected filters, each one
27 connected to the previous one in the sequence. A filterchain is
28 represented by a list of ","-separated filter descriptions.
30 A filtergraph consists of a sequence of filterchains. A sequence of
31 filterchains is represented by a list of ";"-separated filterchain
34 A filter is represented by a string of the form:
35 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
37 @var{filter_name} is the name of the filter class of which the
38 described filter is an instance of, and has to be the name of one of
39 the filter classes registered in the program.
40 The name of the filter class is optionally followed by a string
43 @var{arguments} is a string which contains the parameters used to
44 initialize the filter instance, and are described in the filter
47 The list of arguments can be quoted using the character "'" as initial
48 and ending mark, and the character '\' for escaping the characters
49 within the quoted text; otherwise the argument string is considered
50 terminated when the next special character (belonging to the set
51 "[]=;,") is encountered.
53 The name and arguments of the filter are optionally preceded and
54 followed by a list of link labels.
55 A link label allows to name a link and associate it to a filter output
56 or input pad. The preceding labels @var{in_link_1}
57 ... @var{in_link_N}, are associated to the filter input pads,
58 the following labels @var{out_link_1} ... @var{out_link_M}, are
59 associated to the output pads.
61 When two link labels with the same name are found in the
62 filtergraph, a link between the corresponding input and output pad is
65 If an output pad is not labelled, it is linked by default to the first
66 unlabelled input pad of the next filter in the filterchain.
67 For example in the filterchain:
69 nullsrc, split[L1], [L2]overlay, nullsink
71 the split filter instance has two output pads, and the overlay filter
72 instance two input pads. The first output pad of split is labelled
73 "L1", the first input pad of overlay is labelled "L2", and the second
74 output pad of split is linked to the second input pad of overlay,
75 which are both unlabelled.
77 In a complete filterchain all the unlabelled filter input and output
78 pads must be connected. A filtergraph is considered valid if all the
79 filter input and output pads of all the filterchains are connected.
81 Libavfilter will automatically insert scale filters where format
82 conversion is required. It is possible to specify swscale flags
83 for those automatically inserted scalers by prepending
84 @code{sws_flags=@var{flags};}
85 to the filtergraph description.
87 Follows a BNF description for the filtergraph syntax:
89 @var{NAME} ::= sequence of alphanumeric characters and '_'
90 @var{LINKLABEL} ::= "[" @var{NAME} "]"
91 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
92 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
93 @var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
94 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
95 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
98 @c man end FILTERGRAPH DESCRIPTION
100 @chapter Audio Filters
101 @c man begin AUDIO FILTERS
103 When you configure your Libav build, you can disable any of the
104 existing filters using --disable-filters.
105 The configure output will show the audio filters included in your
108 Below is a description of the currently available audio filters.
112 Pass the audio source unchanged to the output.
114 @c man end AUDIO FILTERS
116 @chapter Audio Sources
117 @c man begin AUDIO SOURCES
119 Below is a description of the currently available audio sources.
123 Null audio source, never return audio frames. It is mainly useful as a
124 template and to be employed in analysis / debugging tools.
126 It accepts as optional parameter a string of the form
127 @var{sample_rate}:@var{channel_layout}.
129 @var{sample_rate} specify the sample rate, and defaults to 44100.
131 @var{channel_layout} specify the channel layout, and can be either an
132 integer or a string representing a channel layout. The default value
133 of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
135 Check the channel_layout_map definition in
136 @file{libavcodec/audioconvert.c} for the mapping between strings and
137 channel layout values.
139 Follow some examples:
141 # set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
148 @c man end AUDIO SOURCES
151 @c man begin AUDIO SINKS
153 Below is a description of the currently available audio sinks.
157 Null audio sink, do absolutely nothing with the input audio. It is
158 mainly useful as a template and to be employed in analysis / debugging
161 @c man end AUDIO SINKS
163 @chapter Video Filters
164 @c man begin VIDEO FILTERS
166 When you configure your Libav build, you can disable any of the
167 existing filters using --disable-filters.
168 The configure output will show the video filters included in your
171 Below is a description of the currently available video filters.
175 Detect frames that are (almost) completely black. Can be useful to
176 detect chapter transitions or commercials. Output lines consist of
177 the frame number of the detected frame, the percentage of blackness,
178 the position in the file if known or -1 and the timestamp in seconds.
180 In order to display the output lines, you need to set the loglevel at
181 least to the AV_LOG_INFO value.
183 The filter accepts the syntax:
185 blackframe[=@var{amount}:[@var{threshold}]]
188 @var{amount} is the percentage of the pixels that have to be below the
189 threshold, and defaults to 98.
191 @var{threshold} is the threshold below which a pixel value is
192 considered black, and defaults to 32.
196 Apply boxblur algorithm to the input video.
198 This filter accepts the parameters:
199 @var{luma_power}:@var{luma_radius}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
201 Chroma and alpha parameters are optional, if not specified they default
202 to the corresponding values set for @var{luma_radius} and
205 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
206 the radius in pixels of the box used for blurring the corresponding
207 input plane. They are expressions, and can contain the following
211 the input width and height in pixels
214 the input chroma image width and height in pixels
217 horizontal and vertical chroma subsample values. For example for the
218 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
221 The radius must be a non-negative number, and must not be greater than
222 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
223 and of @code{min(cw,ch)/2} for the chroma planes.
225 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
226 how many times the boxblur filter is applied to the corresponding
229 Some examples follow:
234 Apply a boxblur filter with luma, chroma, and alpha radius
241 Set luma radius to 2, alpha and chroma radius to 0
247 Set luma and chroma radius to a fraction of the video dimension
249 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
256 Copy the input source unchanged to the output. Mainly useful for
261 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
263 The parameters are expressions containing the following constants:
267 the corresponding mathematical approximated values for e
268 (euler number), pi (greek PI), PHI (golden ratio)
271 the computed values for @var{x} and @var{y}. They are evaluated for
275 the input width and height
278 same as @var{in_w} and @var{in_h}
281 the output (cropped) width and height
284 same as @var{out_w} and @var{out_h}
287 the number of input frame, starting from 0
290 the position in the file of the input frame, NAN if unknown
293 timestamp expressed in seconds, NAN if the input timestamp is unknown
297 The @var{out_w} and @var{out_h} parameters specify the expressions for
298 the width and height of the output (cropped) video. They are
299 evaluated just at the configuration of the filter.
301 The default value of @var{out_w} is "in_w", and the default value of
302 @var{out_h} is "in_h".
304 The expression for @var{out_w} may depend on the value of @var{out_h},
305 and the expression for @var{out_h} may depend on @var{out_w}, but they
306 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
307 evaluated after @var{out_w} and @var{out_h}.
309 The @var{x} and @var{y} parameters specify the expressions for the
310 position of the top-left corner of the output (non-cropped) area. They
311 are evaluated for each frame. If the evaluated value is not valid, it
312 is approximated to the nearest valid value.
314 The default value of @var{x} is "(in_w-out_w)/2", and the default
315 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
316 the center of the input image.
318 The expression for @var{x} may depend on @var{y}, and the expression
319 for @var{y} may depend on @var{x}.
321 Follow some examples:
323 # crop the central input area with size 100x100
326 # crop the central input area with size 2/3 of the input video
327 "crop=2/3*in_w:2/3*in_h"
329 # crop the input video central square
332 # delimit the rectangle with the top-left corner placed at position
333 # 100:100 and the right-bottom corner corresponding to the right-bottom
334 # corner of the input image.
335 crop=in_w-100:in_h-100:100:100
337 # crop 10 pixels from the left and right borders, and 20 pixels from
338 # the top and bottom borders
339 "crop=in_w-2*10:in_h-2*20"
341 # keep only the bottom right quarter of the input image
342 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
344 # crop height for getting Greek harmony
345 "crop=in_w:1/PHI*in_w"
348 "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)"
350 # erratic camera effect depending on timestamp
351 "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)"
353 # set x depending on the value of y
354 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
359 Auto-detect crop size.
361 Calculate necessary cropping parameters and prints the recommended
362 parameters through the logging system. The detected dimensions
363 correspond to the non-black area of the input video.
365 It accepts the syntax:
367 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
373 Threshold, which can be optionally specified from nothing (0) to
374 everything (255), defaults to 24.
377 Value which the width/height should be divisible by, defaults to
378 16. The offset is automatically adjusted to center the video. Use 2 to
379 get only even dimensions (needed for 4:2:2 video). 16 is best when
380 encoding to most video codecs.
383 Counter that determines after how many frames cropdetect will reset
384 the previously detected largest video area and start over to detect
385 the current optimal crop area. Defaults to 0.
387 This can be useful when channel logos distort the video area. 0
388 indicates never reset and return the largest area encountered during
394 Suppress a TV station logo by a simple interpolation of the surrounding
395 pixels. Just set a rectangle covering the logo and watch it disappear
396 (and sometimes something even uglier appear - your mileage may vary).
398 The filter accepts parameters as a string of the form
399 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
400 @var{key}=@var{value} pairs, separated by ":".
402 The description of the accepted parameters follows.
407 Specify the top left corner coordinates of the logo. They must be
411 Specify the width and height of the logo to clear. They must be
415 Specify the thickness of the fuzzy edge of the rectangle (added to
416 @var{w} and @var{h}). The default value is 4.
419 When set to 1, a green rectangle is drawn on the screen to simplify
420 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
421 @var{band} is set to 4. The default value is 0.
425 Some examples follow.
430 Set a rectangle covering the area with top left corner coordinates 0,0
431 and size 100x77, setting a band of size 10:
437 As the previous example, but use named options:
439 delogo=x=0:y=0:w=100:h=77:band=10
446 Draw a colored box on the input image.
448 It accepts the syntax:
450 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
456 Specify the top left corner coordinates of the box. Default to 0.
459 Specify the width and height of the box, if 0 they are interpreted as
460 the input width and height. Default to 0.
463 Specify the color of the box to write, it can be the name of a color
464 (case insensitive match) or a 0xRRGGBB[AA] sequence.
467 Follow some examples:
469 # draw a black box around the edge of the input image
472 # draw a box with color red and an opacity of 50%
473 drawbox=10:20:200:60:red@@0.5"
478 Draw text string or text from specified file on top of video using the
481 To enable compilation of this filter you need to configure Libav with
482 @code{--enable-libfreetype}.
484 The filter also recognizes strftime() sequences in the provided text
485 and expands them accordingly. Check the documentation of strftime().
487 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
490 The description of the accepted parameters follows.
495 The font file to be used for drawing text. Path must be included.
496 This parameter is mandatory.
499 The text string to be drawn. The text must be a sequence of UTF-8
501 This parameter is mandatory if no file is specified with the parameter
505 A text file containing text to be drawn. The text must be a sequence
506 of UTF-8 encoded characters.
508 This parameter is mandatory if no text string is specified with the
509 parameter @var{text}.
511 If both text and textfile are specified, an error is thrown.
514 The offsets where text will be drawn within the video frame.
515 Relative to the top/left border of the output image.
516 They accept expressions similar to the @ref{overlay} filter:
520 the computed values for @var{x} and @var{y}. They are evaluated for
524 main input width and height
527 same as @var{main_w} and @var{main_h}
530 rendered text width and height
533 same as @var{text_w} and @var{text_h}
536 the number of frames processed, starting from 0
539 timestamp expressed in seconds, NAN if the input timestamp is unknown
543 The default value of @var{x} and @var{y} is 0.
546 The font size to be used for drawing text.
547 The default value of @var{fontsize} is 16.
550 The color to be used for drawing fonts.
551 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
552 (e.g. "0xff000033"), possibly followed by an alpha specifier.
553 The default value of @var{fontcolor} is "black".
556 The color to be used for drawing box around text.
557 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
558 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
559 The default value of @var{boxcolor} is "white".
562 Used to draw a box around text using background color.
563 Value should be either 1 (enable) or 0 (disable).
564 The default value of @var{box} is 0.
566 @item shadowx, shadowy
567 The x and y offsets for the text shadow position with respect to the
568 position of the text. They can be either positive or negative
569 values. Default value for both is "0".
572 The color to be used for drawing a shadow behind the drawn text. It
573 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
574 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
575 The default value of @var{shadowcolor} is "black".
578 Flags to be used for loading the fonts.
580 The flags map the corresponding flags supported by libfreetype, and are
581 a combination of the following values:
588 @item vertical_layout
592 @item ignore_global_advance_width
594 @item ignore_transform
601 Default value is "render".
603 For more information consult the documentation for the FT_LOAD_*
607 The size in number of spaces to use for rendering the tab.
611 If true, check and fix text coords to avoid clipping.
614 For example the command:
616 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
619 will draw "Test Text" with font FreeSerif, using the default values
620 for the optional parameters.
624 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
625 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
628 will draw 'Test Text' with font FreeSerif of size 24 at position x=100
629 and y=50 (counting from the top-left corner of the screen), text is
630 yellow with a red box around it. Both the text and the box have an
633 Note that the double quotes are not necessary if spaces are not used
634 within the parameter list.
636 For more information about libfreetype, check:
637 @url{http://www.freetype.org/}.
641 Apply fade-in/out effect to input video.
643 It accepts the parameters:
644 @var{type}:@var{start_frame}:@var{nb_frames}
646 @var{type} specifies if the effect type, can be either "in" for
647 fade-in, or "out" for a fade-out effect.
649 @var{start_frame} specifies the number of the start frame for starting
650 to apply the fade effect.
652 @var{nb_frames} specifies the number of frames for which the fade
653 effect has to last. At the end of the fade-in effect the output video
654 will have the same intensity as the input video, at the end of the
655 fade-out transition the output video will be completely black.
657 A few usage examples follow, usable too as test scenarios.
659 # fade in first 30 frames of video
662 # fade out last 45 frames of a 200-frame video
665 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
666 fade=in:0:25, fade=out:975:25
668 # make first 5 frames black, then fade in from frame 5-24
674 Transform the field order of the input video.
676 It accepts one parameter which specifies the required field order that
677 the input interlaced video will be transformed to. The parameter can
678 assume one of the following values:
682 output bottom field first
684 output top field first
687 Default value is "tff".
689 Transformation is achieved by shifting the picture content up or down
690 by one line, and filling the remaining line with appropriate picture content.
691 This method is consistent with most broadcast field order converters.
693 If the input video is not flagged as being interlaced, or it is already
694 flagged as being of the required output field order then this filter does
695 not alter the incoming video.
697 This filter is very useful when converting to or from PAL DV material,
698 which is bottom field first.
702 ./avconv -i in.vob -vf "fieldorder=bff" out.dv
707 Buffer input images and send them when they are requested.
709 This filter is mainly useful when auto-inserted by the libavfilter
712 The filter does not take parameters.
716 Convert the input video to one of the specified pixel formats.
717 Libavfilter will try to pick one that is supported for the input to
720 The filter accepts a list of pixel format names, separated by ":",
721 for example "yuv420p:monow:rgb24".
723 Some examples follow:
725 # convert the input video to the format "yuv420p"
728 # convert the input video to any of the formats in the list
729 format=yuv420p:yuv444p:yuv410p
735 Apply a frei0r effect to the input video.
737 To enable compilation of this filter you need to install the frei0r
738 header and configure Libav with --enable-frei0r.
740 The filter supports the syntax:
742 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
745 @var{filter_name} is the name to the frei0r effect to load. If the
746 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
747 is searched in each one of the directories specified by the colon
748 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
749 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
750 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
752 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
753 for the frei0r effect.
755 A frei0r effect parameter can be a boolean (whose values are specified
756 with "y" and "n"), a double, a color (specified by the syntax
757 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
758 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
759 description), a position (specified by the syntax @var{X}/@var{Y},
760 @var{X} and @var{Y} being float numbers) and a string.
762 The number and kind of parameters depend on the loaded effect. If an
763 effect parameter is not specified the default value is set.
765 Some examples follow:
767 # apply the distort0r effect, set the first two double parameters
768 frei0r=distort0r:0.5:0.01
770 # apply the colordistance effect, takes a color as first parameter
771 frei0r=colordistance:0.2/0.3/0.4
772 frei0r=colordistance:violet
773 frei0r=colordistance:0x112233
775 # apply the perspective effect, specify the top left and top right
777 frei0r=perspective:0.2/0.2:0.8/0.2
780 For more information see:
781 @url{http://piksel.org/frei0r}
785 Fix the banding artifacts that are sometimes introduced into nearly flat
786 regions by truncation to 8bit colordepth.
787 Interpolate the gradients that should go where the bands are, and
790 This filter is designed for playback only. Do not use it prior to
791 lossy compression, because compression tends to lose the dither and
792 bring back the bands.
794 The filter takes two optional parameters, separated by ':':
795 @var{strength}:@var{radius}
797 @var{strength} is the maximum amount by which the filter will change
798 any one pixel. Also the threshold for detecting nearly flat
799 regions. Acceptable values range from .51 to 255, default value is
800 1.2, out-of-range values will be clipped to the valid range.
802 @var{radius} is the neighborhood to fit the gradient to. A larger
803 radius makes for smoother gradients, but also prevents the filter from
804 modifying the pixels near detailed regions. Acceptable values are
805 8-32, default value is 16, out-of-range values will be clipped to the
818 Flip the input video horizontally.
820 For example to horizontally flip the input video with @command{avconv}:
822 avconv -i in.avi -vf "hflip" out.avi
827 High precision/quality 3d denoise filter. This filter aims to reduce
828 image noise producing smooth images and making still images really
829 still. It should enhance compressibility.
831 It accepts the following optional parameters:
832 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
836 a non-negative float number which specifies spatial luma strength,
840 a non-negative float number which specifies spatial chroma strength,
841 defaults to 3.0*@var{luma_spatial}/4.0
844 a float number which specifies luma temporal strength, defaults to
845 6.0*@var{luma_spatial}/4.0
848 a float number which specifies chroma temporal strength, defaults to
849 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
852 @section lut, lutrgb, lutyuv
854 Compute a look-up table for binding each pixel component input value
855 to an output value, and apply it to input video.
857 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
858 to an RGB input video.
860 These filters accept in input a ":"-separated list of options, which
861 specify the expressions used for computing the lookup table for the
862 corresponding pixel component values.
864 The @var{lut} filter requires either YUV or RGB pixel formats in
865 input, and accepts the options:
867 @var{c0} (first pixel component)
868 @var{c1} (second pixel component)
869 @var{c2} (third pixel component)
870 @var{c3} (fourth pixel component, corresponds to the alpha component)
873 The exact component associated to each option depends on the format in
876 The @var{lutrgb} filter requires RGB pixel formats in input, and
879 @var{r} (red component)
880 @var{g} (green component)
881 @var{b} (blue component)
882 @var{a} (alpha component)
885 The @var{lutyuv} filter requires YUV pixel formats in input, and
888 @var{y} (Y/luminance component)
889 @var{u} (U/Cb component)
890 @var{v} (V/Cr component)
891 @var{a} (alpha component)
894 The expressions can contain the following constants and functions:
898 the corresponding mathematical approximated values for e
899 (euler number), pi (greek PI), PHI (golden ratio)
902 the input width and height
905 input value for the pixel component
908 the input value clipped in the @var{minval}-@var{maxval} range
911 maximum value for the pixel component
914 minimum value for the pixel component
917 the negated value for the pixel component value clipped in the
918 @var{minval}-@var{maxval} range , it corresponds to the expression
919 "maxval-clipval+minval"
922 the computed value in @var{val} clipped in the
923 @var{minval}-@var{maxval} range
925 @item gammaval(gamma)
926 the computed gamma correction value of the pixel component value
927 clipped in the @var{minval}-@var{maxval} range, corresponds to the
929 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
933 All expressions default to "val".
935 Some examples follow:
938 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
939 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
941 # the above is the same as
942 lutrgb="r=negval:g=negval:b=negval"
943 lutyuv="y=negval:u=negval:v=negval"
948 # remove chroma components, turns the video into a graytone image
951 # apply a luma burning effect
954 # remove green and blue components
957 # set a constant alpha channel value on input
958 format=rgba,lutrgb=a="maxval-minval/2"
960 # correct luminance gamma by a 0.5 factor
961 lutyuv=y=gammaval(0.5)
968 This filter accepts an integer in input, if non-zero it negates the
969 alpha component (if available). The default value in input is 0.
971 Force libavfilter not to use any of the specified pixel formats for the
972 input to the next filter.
974 The filter accepts a list of pixel format names, separated by ":",
975 for example "yuv420p:monow:rgb24".
977 Some examples follow:
979 # force libavfilter to use a format different from "yuv420p" for the
980 # input to the vflip filter
981 noformat=yuv420p,vflip
983 # convert the input video to any of the formats not contained in the list
984 noformat=yuv420p:yuv444p:yuv410p
989 Pass the video source unchanged to the output.
993 Apply video transform using libopencv.
995 To enable this filter install libopencv library and headers and
996 configure Libav with --enable-libopencv.
998 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1000 @var{filter_name} is the name of the libopencv filter to apply.
1002 @var{filter_params} specifies the parameters to pass to the libopencv
1003 filter. If not specified the default values are assumed.
1005 Refer to the official libopencv documentation for more precise
1007 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1009 Follows the list of supported libopencv filters.
1014 Dilate an image by using a specific structuring element.
1015 This filter corresponds to the libopencv function @code{cvDilate}.
1017 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1019 @var{struct_el} represents a structuring element, and has the syntax:
1020 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1022 @var{cols} and @var{rows} represent the number of columns and rows of
1023 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1024 point, and @var{shape} the shape for the structuring element, and
1025 can be one of the values "rect", "cross", "ellipse", "custom".
1027 If the value for @var{shape} is "custom", it must be followed by a
1028 string of the form "=@var{filename}". The file with name
1029 @var{filename} is assumed to represent a binary image, with each
1030 printable character corresponding to a bright pixel. When a custom
1031 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1032 or columns and rows of the read file are assumed instead.
1034 The default value for @var{struct_el} is "3x3+0x0/rect".
1036 @var{nb_iterations} specifies the number of times the transform is
1037 applied to the image, and defaults to 1.
1039 Follow some example:
1041 # use the default values
1044 # dilate using a structuring element with a 5x5 cross, iterate two times
1045 ocv=dilate=5x5+2x2/cross:2
1047 # read the shape from the file diamond.shape, iterate two times
1048 # the file diamond.shape may contain a pattern of characters like this:
1054 # the specified cols and rows are ignored (but not the anchor point coordinates)
1055 ocv=0x0+2x2/custom=diamond.shape:2
1060 Erode an image by using a specific structuring element.
1061 This filter corresponds to the libopencv function @code{cvErode}.
1063 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1064 with the same syntax and semantics as the @ref{dilate} filter.
1068 Smooth the input video.
1070 The filter takes the following parameters:
1071 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1073 @var{type} is the type of smooth filter to apply, and can be one of
1074 the following values: "blur", "blur_no_scale", "median", "gaussian",
1075 "bilateral". The default value is "gaussian".
1077 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1078 parameters whose meanings depend on smooth type. @var{param1} and
1079 @var{param2} accept integer positive values or 0, @var{param3} and
1080 @var{param4} accept float values.
1082 The default value for @var{param1} is 3, the default value for the
1083 other parameters is 0.
1085 These parameters correspond to the parameters assigned to the
1086 libopencv function @code{cvSmooth}.
1091 Overlay one video on top of another.
1093 It takes two inputs and one output, the first input is the "main"
1094 video on which the second input is overlayed.
1096 It accepts the parameters: @var{x}:@var{y}.
1098 @var{x} is the x coordinate of the overlayed video on the main video,
1099 @var{y} is the y coordinate. The parameters are expressions containing
1100 the following parameters:
1103 @item main_w, main_h
1104 main input width and height
1107 same as @var{main_w} and @var{main_h}
1109 @item overlay_w, overlay_h
1110 overlay input width and height
1113 same as @var{overlay_w} and @var{overlay_h}
1116 Be aware that frames are taken from each input video in timestamp
1117 order, hence, if their initial timestamps differ, it is a a good idea
1118 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1119 have them begin in the same zero timestamp, as it does the example for
1120 the @var{movie} filter.
1122 Follow some examples:
1124 # draw the overlay at 10 pixels from the bottom right
1125 # corner of the main video.
1126 overlay=main_w-overlay_w-10:main_h-overlay_h-10
1128 # insert a transparent PNG logo in the bottom left corner of the input
1129 avconv -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
1131 # insert 2 different transparent PNG logos (second logo on bottom
1133 avconv -i input -i logo1 -i logo2 -filter_complex
1134 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
1136 # add a transparent color layer on top of the main video,
1137 # WxH specifies the size of the main input to the overlay filter
1138 color=red@.3:WxH [over]; [in][over] overlay [out]
1141 You can chain together more overlays but the efficiency of such
1142 approach is yet to be tested.
1146 Add paddings to the input image, and places the original input at the
1147 given coordinates @var{x}, @var{y}.
1149 It accepts the following parameters:
1150 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1152 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1153 expressions containing the following constants:
1157 the corresponding mathematical approximated values for e
1158 (euler number), pi (greek PI), phi (golden ratio)
1161 the input video width and height
1164 same as @var{in_w} and @var{in_h}
1167 the output width and height, that is the size of the padded area as
1168 specified by the @var{width} and @var{height} expressions
1171 same as @var{out_w} and @var{out_h}
1174 x and y offsets as specified by the @var{x} and @var{y}
1175 expressions, or NAN if not yet specified
1178 input display aspect ratio, same as @var{iw} / @var{ih}
1181 horizontal and vertical chroma subsample values. For example for the
1182 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1185 Follows the description of the accepted parameters.
1190 Specify the size of the output image with the paddings added. If the
1191 value for @var{width} or @var{height} is 0, the corresponding input size
1192 is used for the output.
1194 The @var{width} expression can reference the value set by the
1195 @var{height} expression, and vice versa.
1197 The default value of @var{width} and @var{height} is 0.
1201 Specify the offsets where to place the input image in the padded area
1202 with respect to the top/left border of the output image.
1204 The @var{x} expression can reference the value set by the @var{y}
1205 expression, and vice versa.
1207 The default value of @var{x} and @var{y} is 0.
1211 Specify the color of the padded area, it can be the name of a color
1212 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1214 The default value of @var{color} is "black".
1218 Some examples follow:
1221 # Add paddings with color "violet" to the input video. Output video
1222 # size is 640x480, the top-left corner of the input video is placed at
1224 pad=640:480:0:40:violet
1226 # pad the input to get an output with dimensions increased bt 3/2,
1227 # and put the input video at the center of the padded area
1228 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1230 # pad the input to get a squared output with size equal to the maximum
1231 # value between the input width and height, and put the input video at
1232 # the center of the padded area
1233 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1235 # pad the input to get a final w/h ratio of 16:9
1236 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1238 # double output size and put the input video in the bottom-right
1239 # corner of the output padded area
1240 pad="2*iw:2*ih:ow-iw:oh-ih"
1243 @section pixdesctest
1245 Pixel format descriptor test filter, mainly useful for internal
1246 testing. The output video should be equal to the input video.
1250 format=monow, pixdesctest
1253 can be used to test the monowhite pixel format descriptor definition.
1257 Scale the input video to @var{width}:@var{height} and/or convert the image format.
1259 The parameters @var{width} and @var{height} are expressions containing
1260 the following constants:
1264 the corresponding mathematical approximated values for e
1265 (euler number), pi (greek PI), phi (golden ratio)
1268 the input width and height
1271 same as @var{in_w} and @var{in_h}
1274 the output (cropped) width and height
1277 same as @var{out_w} and @var{out_h}
1280 input display aspect ratio, same as @var{iw} / @var{ih}
1283 input sample aspect ratio
1286 horizontal and vertical chroma subsample values. For example for the
1287 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1290 If the input image format is different from the format requested by
1291 the next filter, the scale filter will convert the input to the
1294 If the value for @var{width} or @var{height} is 0, the respective input
1295 size is used for the output.
1297 If the value for @var{width} or @var{height} is -1, the scale filter will
1298 use, for the respective output size, a value that maintains the aspect
1299 ratio of the input image.
1301 The default value of @var{width} and @var{height} is 0.
1303 Some examples follow:
1305 # scale the input video to a size of 200x100.
1308 # scale the input to 2x
1310 # the above is the same as
1313 # scale the input to half size
1316 # increase the width, and set the height to the same size
1319 # seek for Greek harmony
1323 # increase the height, and set the width to 3/2 of the height
1326 # increase the size, but make the size a multiple of the chroma
1327 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1329 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1330 scale='min(500\, iw*3/2):-1'
1334 Select frames to pass in output.
1336 It accepts in input an expression, which is evaluated for each input
1337 frame. If the expression is evaluated to a non-zero value, the frame
1338 is selected and passed to the output, otherwise it is discarded.
1340 The expression can contain the following constants:
1353 the sequential number of the filtered frame, starting from 0
1356 the sequential number of the selected frame, starting from 0
1358 @item prev_selected_n
1359 the sequential number of the last selected frame, NAN if undefined
1362 timebase of the input timestamps
1365 the PTS (Presentation TimeStamp) of the filtered video frame,
1366 expressed in @var{TB} units, NAN if undefined
1369 the PTS (Presentation TimeStamp) of the filtered video frame,
1370 expressed in seconds, NAN if undefined
1373 the PTS of the previously filtered video frame, NAN if undefined
1375 @item prev_selected_pts
1376 the PTS of the last previously filtered video frame, NAN if undefined
1378 @item prev_selected_t
1379 the PTS of the last previously selected video frame, NAN if undefined
1382 the PTS of the first video frame in the video, NAN if undefined
1385 the time of the first video frame in the video, NAN if undefined
1388 the type of the filtered frame, can assume one of the following
1400 @item interlace_type
1401 the frame interlace type, can assume one of the following values:
1404 the frame is progressive (not interlaced)
1406 the frame is top-field-first
1408 the frame is bottom-field-first
1412 1 if the filtered frame is a key-frame, 0 otherwise
1415 the position in the file of the filtered frame, -1 if the information
1416 is not available (e.g. for synthetic video)
1419 The default value of the select expression is "1".
1421 Some examples follow:
1424 # select all frames in input
1427 # the above is the same as:
1433 # select only I-frames
1434 select='eq(pict_type\,I)'
1436 # select one frame every 100
1437 select='not(mod(n\,100))'
1439 # select only frames contained in the 10-20 time interval
1440 select='gte(t\,10)*lte(t\,20)'
1442 # select only I frames contained in the 10-20 time interval
1443 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
1445 # select frames with a minimum distance of 10 seconds
1446 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
1452 Set the Display Aspect Ratio for the filter output video.
1454 This is done by changing the specified Sample (aka Pixel) Aspect
1455 Ratio, according to the following equation:
1456 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1458 Keep in mind that this filter does not modify the pixel dimensions of
1459 the video frame. Also the display aspect ratio set by this filter may
1460 be changed by later filters in the filterchain, e.g. in case of
1461 scaling or if another "setdar" or a "setsar" filter is applied.
1463 The filter accepts a parameter string which represents the wanted
1464 display aspect ratio.
1465 The parameter can be a floating point number string, or an expression
1466 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1467 numerator and denominator of the aspect ratio.
1468 If the parameter is not specified, it is assumed the value "0:1".
1470 For example to change the display aspect ratio to 16:9, specify:
1473 # the above is equivalent to
1477 See also the @ref{setsar} filter documentation.
1481 Change the PTS (presentation timestamp) of the input video frames.
1483 Accept in input an expression evaluated through the eval API, which
1484 can contain the following constants:
1488 the presentation timestamp in input
1500 the count of the input frame, starting from 0.
1503 the PTS of the first video frame
1506 tell if the current frame is interlaced
1509 original position in the file of the frame, or undefined if undefined
1510 for the current frame
1520 Some examples follow:
1523 # start counting PTS from zero
1535 # fixed rate 25 fps with some jitter
1536 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1542 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1544 Note that as a consequence of the application of this filter, the
1545 output display aspect ratio will change according to the following
1547 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1549 Keep in mind that the sample aspect ratio set by this filter may be
1550 changed by later filters in the filterchain, e.g. if another "setsar"
1551 or a "setdar" filter is applied.
1553 The filter accepts a parameter string which represents the wanted
1554 sample aspect ratio.
1555 The parameter can be a floating point number string, or an expression
1556 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1557 numerator and denominator of the aspect ratio.
1558 If the parameter is not specified, it is assumed the value "0:1".
1560 For example to change the sample aspect ratio to 10:11, specify:
1567 Set the timebase to use for the output frames timestamps.
1568 It is mainly useful for testing timebase configuration.
1570 It accepts in input an arithmetic expression representing a rational.
1571 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1572 default timebase), and "intb" (the input timebase).
1574 The default value for the input is "intb".
1576 Follow some examples.
1579 # set the timebase to 1/25
1582 # set the timebase to 1/10
1585 #set the timebase to 1001/1000
1588 #set the timebase to 2*intb
1591 #set the default timebase value
1597 Show a line containing various information for each input video frame.
1598 The input video is not modified.
1600 The shown line contains a sequence of key/value pairs of the form
1601 @var{key}:@var{value}.
1603 A description of each shown parameter follows:
1607 sequential number of the input frame, starting from 0
1610 Presentation TimeStamp of the input frame, expressed as a number of
1611 time base units. The time base unit depends on the filter input pad.
1614 Presentation TimeStamp of the input frame, expressed as a number of
1618 position of the frame in the input stream, -1 if this information in
1619 unavailable and/or meaningless (for example in case of synthetic video)
1625 sample aspect ratio of the input frame, expressed in the form
1629 size of the input frame, expressed in the form
1630 @var{width}x@var{height}
1633 interlaced mode ("P" for "progressive", "T" for top field first, "B"
1634 for bottom field first)
1637 1 if the frame is a key frame, 0 otherwise
1640 picture type of the input frame ("I" for an I-frame, "P" for a
1641 P-frame, "B" for a B-frame, "?" for unknown type).
1642 Check also the documentation of the @code{AVPictureType} enum and of
1643 the @code{av_get_picture_type_char} function defined in
1644 @file{libavutil/avutil.h}.
1647 Adler-32 checksum of all the planes of the input frame
1649 @item plane_checksum
1650 Adler-32 checksum of each plane of the input frame, expressed in the form
1651 "[@var{c0} @var{c1} @var{c2} @var{c3}]"
1656 Pass the images of input video on to next video filter as multiple
1660 ./avconv -i in.avi -vf "slicify=32" out.avi
1663 The filter accepts the slice height as parameter. If the parameter is
1664 not specified it will use the default value of 16.
1666 Adding this in the beginning of filter chains should make filtering
1667 faster due to better use of the memory cache.
1671 Transpose rows with columns in the input video and optionally flip it.
1673 It accepts a parameter representing an integer, which can assume the
1678 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1686 Rotate by 90 degrees clockwise, that is:
1694 Rotate by 90 degrees counterclockwise, that is:
1702 Rotate by 90 degrees clockwise and vertically flip, that is:
1712 Sharpen or blur the input video.
1714 It accepts the following parameters:
1715 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1717 Negative values for the amount will blur the input video, while positive
1718 values will sharpen. All parameters are optional and default to the
1719 equivalent of the string '5:5:1.0:5:5:0.0'.
1724 Set the luma matrix horizontal size. It can be an integer between 3
1725 and 13, default value is 5.
1728 Set the luma matrix vertical size. It can be an integer between 3
1729 and 13, default value is 5.
1732 Set the luma effect strength. It can be a float number between -2.0
1733 and 5.0, default value is 1.0.
1735 @item chroma_msize_x
1736 Set the chroma matrix horizontal size. It can be an integer between 3
1737 and 13, default value is 5.
1739 @item chroma_msize_y
1740 Set the chroma matrix vertical size. It can be an integer between 3
1741 and 13, default value is 5.
1744 Set the chroma effect strength. It can be a float number between -2.0
1745 and 5.0, default value is 0.0.
1750 # Strong luma sharpen effect parameters
1753 # Strong blur of both luma and chroma parameters
1754 unsharp=7:7:-2:7:7:-2
1756 # Use the default values with @command{avconv}
1757 ./avconv -i in.avi -vf "unsharp" out.mp4
1762 Flip the input video vertically.
1765 ./avconv -i in.avi -vf "vflip" out.avi
1770 Deinterlace the input video ("yadif" means "yet another deinterlacing
1773 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
1775 @var{mode} specifies the interlacing mode to adopt, accepts one of the
1780 output 1 frame for each frame
1782 output 1 frame for each field
1784 like 0 but skips spatial interlacing check
1786 like 1 but skips spatial interlacing check
1791 @var{parity} specifies the picture field parity assumed for the input
1792 interlaced video, accepts one of the following values:
1796 assume top field first
1798 assume bottom field first
1800 enable automatic detection
1803 Default value is -1.
1804 If interlacing is unknown or decoder does not export this information,
1805 top field first will be assumed.
1807 @var{auto} specifies if deinterlacer should trust the interlaced flag
1808 and only deinterlace frames marked as interlaced
1812 deinterlace all frames
1814 only deinterlace frames marked as interlaced
1819 @c man end VIDEO FILTERS
1821 @chapter Video Sources
1822 @c man begin VIDEO SOURCES
1824 Below is a description of the currently available video sources.
1828 Buffer video frames, and make them available to the filter chain.
1830 This source is mainly intended for a programmatic use, in particular
1831 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1833 It accepts the following parameters:
1834 @var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1836 All the parameters need to be explicitly defined.
1838 Follows the list of the accepted parameters.
1843 Specify the width and height of the buffered video frames.
1845 @item pix_fmt_string
1846 A string representing the pixel format of the buffered video frames.
1847 It may be a number corresponding to a pixel format, or a pixel format
1850 @item timebase_num, timebase_den
1851 Specify numerator and denomitor of the timebase assumed by the
1852 timestamps of the buffered frames.
1854 @item sample_aspect_ratio.num, sample_aspect_ratio.den
1855 Specify numerator and denominator of the sample aspect ratio assumed
1856 by the video frames.
1861 buffer=320:240:yuv410p:1:24:1:1
1864 will instruct the source to accept video frames with size 320x240 and
1865 with format "yuv410p", assuming 1/24 as the timestamps timebase and
1866 square pixels (1:1 sample aspect ratio).
1867 Since the pixel format with name "yuv410p" corresponds to the number 6
1868 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1869 this example corresponds to:
1871 buffer=320:240:6:1:24
1876 Provide an uniformly colored input.
1878 It accepts the following parameters:
1879 @var{color}:@var{frame_size}:@var{frame_rate}
1881 Follows the description of the accepted parameters.
1886 Specify the color of the source. It can be the name of a color (case
1887 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1888 alpha specifier. The default value is "black".
1891 Specify the size of the sourced video, it may be a string of the form
1892 @var{width}x@var{height}, or the name of a size abbreviation. The
1893 default value is "320x240".
1896 Specify the frame rate of the sourced video, as the number of frames
1897 generated per second. It has to be a string in the format
1898 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1899 number or a valid video frame rate abbreviation. The default value is
1904 For example the following graph description will generate a red source
1905 with an opacity of 0.2, with size "qcif" and a frame rate of 10
1906 frames per second, which will be overlayed over the source connected
1907 to the pad with identifier "in".
1910 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1915 Read a video stream from a movie container.
1917 It accepts the syntax: @var{movie_name}[:@var{options}] where
1918 @var{movie_name} is the name of the resource to read (not necessarily
1919 a file but also a device or a stream accessed through some protocol),
1920 and @var{options} is an optional sequence of @var{key}=@var{value}
1921 pairs, separated by ":".
1923 The description of the accepted options follows.
1927 @item format_name, f
1928 Specifies the format assumed for the movie to read, and can be either
1929 the name of a container or an input device. If not specified the
1930 format is guessed from @var{movie_name} or by probing.
1932 @item seek_point, sp
1933 Specifies the seek point in seconds, the frames will be output
1934 starting from this seek point, the parameter is evaluated with
1935 @code{av_strtod} so the numerical value may be suffixed by an IS
1936 postfix. Default value is "0".
1938 @item stream_index, si
1939 Specifies the index of the video stream to read. If the value is -1,
1940 the best suited video stream will be automatically selected. Default
1945 This filter allows to overlay a second video on top of main input of
1946 a filtergraph as shown in this graph:
1948 input -----------> deltapts0 --> overlay --> output
1951 movie --> scale--> deltapts1 -------+
1954 Some examples follow:
1956 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1957 # on top of the input labelled as "in".
1958 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1959 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1961 # read from a video4linux2 device, and overlay it on top of the input
1963 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1964 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1970 Null video source, never return images. It is mainly useful as a
1971 template and to be employed in analysis / debugging tools.
1973 It accepts as optional parameter a string of the form
1974 @var{width}:@var{height}:@var{timebase}.
1976 @var{width} and @var{height} specify the size of the configured
1977 source. The default values of @var{width} and @var{height} are
1978 respectively 352 and 288 (corresponding to the CIF size format).
1980 @var{timebase} specifies an arithmetic expression representing a
1981 timebase. The expression can contain the constants "PI", "E", "PHI",
1982 "AVTB" (the default timebase), and defaults to the value "AVTB".
1986 Provide a frei0r source.
1988 To enable compilation of this filter you need to install the frei0r
1989 header and configure Libav with --enable-frei0r.
1991 The source supports the syntax:
1993 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1996 @var{size} is the size of the video to generate, may be a string of the
1997 form @var{width}x@var{height} or a frame size abbreviation.
1998 @var{rate} is the rate of the video to generate, may be a string of
1999 the form @var{num}/@var{den} or a frame rate abbreviation.
2000 @var{src_name} is the name to the frei0r source to load. For more
2001 information regarding frei0r and how to set the parameters read the
2002 section @ref{frei0r} in the description of the video filters.
2004 Some examples follow:
2006 # generate a frei0r partik0l source with size 200x200 and framerate 10
2007 # which is overlayed on the overlay filter main input
2008 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
2011 @section rgbtestsrc, testsrc
2013 The @code{rgbtestsrc} source generates an RGB test pattern useful for
2014 detecting RGB vs BGR issues. You should see a red, green and blue
2015 stripe from top to bottom.
2017 The @code{testsrc} source generates a test video pattern, showing a
2018 color pattern, a scrolling gradient and a timestamp. This is mainly
2019 intended for testing purposes.
2021 Both sources accept an optional sequence of @var{key}=@var{value} pairs,
2022 separated by ":". The description of the accepted options follows.
2027 Specify the size of the sourced video, it may be a string of the form
2028 @var{width}x@var{height}, or the name of a size abbreviation. The
2029 default value is "320x240".
2032 Specify the frame rate of the sourced video, as the number of frames
2033 generated per second. It has to be a string in the format
2034 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2035 number or a valid video frame rate abbreviation. The default value is
2039 Set the sample aspect ratio of the sourced video.
2042 Set the video duration of the sourced video. The accepted syntax is:
2044 [-]HH[:MM[:SS[.m...]]]
2047 See also the function @code{av_parse_time()}.
2049 If not specified, or the expressed duration is negative, the video is
2050 supposed to be generated forever.
2053 For example the following:
2055 testsrc=duration=5.3:size=qcif:rate=10
2058 will generate a video with a duration of 5.3 seconds, with size
2059 176x144 and a framerate of 10 frames per second.
2061 @c man end VIDEO SOURCES
2063 @chapter Video Sinks
2064 @c man begin VIDEO SINKS
2066 Below is a description of the currently available video sinks.
2070 Null video sink, do absolutely nothing with the input video. It is
2071 mainly useful as a template and to be employed in analysis / debugging
2074 @c man end VIDEO SINKS