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 @section Filtergraph syntax
19 A filtergraph can be represented using a textual representation, which
20 is recognized by the @code{-vf} and @code{-af} options in @command{avconv}
21 and @command{avplay}, and by the @code{av_parse_graph()} function defined in
22 @file{libavfilter/avfiltergraph}.
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.
28 A filtergraph consists of a sequence of filterchains. A sequence of
29 filterchains is represented by a list of ";"-separated filterchain
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}]
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
41 @var{arguments} is a string which contains the parameters used to
42 initialize the filter instance, and are described in the filter
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.
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.
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
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:
67 nullsrc, split[L1], [L2]overlay, nullsink
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.
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.
79 Follows a BNF description for the filtergraph syntax:
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}]
90 @c man end FILTERGRAPH DESCRIPTION
92 @chapter Audio Filters
93 @c man begin AUDIO FILTERS
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
100 Below is a description of the currently available audio filters.
104 Pass the audio source unchanged to the output.
106 @c man end AUDIO FILTERS
108 @chapter Audio Sources
109 @c man begin AUDIO SOURCES
111 Below is a description of the currently available audio sources.
115 Null audio source, never return audio frames. It is mainly useful as a
116 template and to be employed in analysis / debugging tools.
118 It accepts as optional parameter a string of the form
119 @var{sample_rate}:@var{channel_layout}.
121 @var{sample_rate} specify the sample rate, and defaults to 44100.
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.
127 Check the channel_layout_map definition in
128 @file{libavcodec/audioconvert.c} for the mapping between strings and
129 channel layout values.
131 Follow some examples:
133 # set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
140 @c man end AUDIO SOURCES
143 @c man begin AUDIO SINKS
145 Below is a description of the currently available audio sinks.
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
153 @c man end AUDIO SINKS
155 @chapter Video Filters
156 @c man begin VIDEO FILTERS
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
163 Below is a description of the currently available video filters.
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.
172 In order to display the output lines, you need to set the loglevel at
173 least to the AV_LOG_INFO value.
175 The filter accepts the syntax:
177 blackframe[=@var{amount}:[@var{threshold}]]
180 @var{amount} is the percentage of the pixels that have to be below the
181 threshold, and defaults to 98.
183 @var{threshold} is the threshold below which a pixel value is
184 considered black, and defaults to 32.
188 Apply boxblur algorithm to the input video.
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}
193 Chroma and alpha parameters are optional, if not specified they default
194 to the corresponding values set for @var{luma_radius} and
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
203 the input width and heigth in pixels
206 the input chroma image width and height in pixels
209 horizontal and vertical chroma subsample values. For example for the
210 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
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.
217 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
218 how many times the boxblur filter is applied to the corresponding
221 Some examples follow:
226 Apply a boxblur filter with luma, chroma, and alpha radius
233 Set luma radius to 2, alpha and chroma radius to 0
239 Set luma and chroma radius to a fraction of the video dimension
241 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
248 Copy the input source unchanged to the output. Mainly useful for
253 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
255 The parameters are expressions containing the following constants:
259 the corresponding mathematical approximated values for e
260 (euler number), pi (greek PI), PHI (golden ratio)
263 the computed values for @var{x} and @var{y}. They are evaluated for
267 the input width and height
270 same as @var{in_w} and @var{in_h}
273 the output (cropped) width and height
276 same as @var{out_w} and @var{out_h}
279 the number of input frame, starting from 0
282 the position in the file of the input frame, NAN if unknown
285 timestamp expressed in seconds, NAN if the input timestamp is unknown
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.
293 The default value of @var{out_w} is "in_w", and the default value of
294 @var{out_h} is "in_h".
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}.
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.
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.
310 The expression for @var{x} may depend on @var{y}, and the expression
311 for @var{y} may depend on @var{x}.
313 Follow some examples:
315 # crop the central input area with size 100x100
318 # crop the central input area with size 2/3 of the input video
319 "crop=2/3*in_w:2/3*in_h"
321 # crop the input video central square
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
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"
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"
336 # crop height for getting Greek harmony
337 "crop=in_w:1/PHI*in_w"
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)"
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)"
345 # set x depending on the value of y
346 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
351 Auto-detect crop size.
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.
357 It accepts the syntax:
359 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
365 Threshold, which can be optionally specified from nothing (0) to
366 everything (255), defaults to 24.
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.
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.
379 This can be useful when channel logos distort the video area. 0
380 indicates never reset and return the largest area encountered during
386 Suppress a TV station logo by a simple interpolation of the surrounding
387 pixels. Just set a rectangle covering the logo and watch it disappear
388 (and sometimes something even uglier appear - your mileage may vary).
390 The filter accepts parameters as a string of the form
391 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
392 @var{key}=@var{value} pairs, separated by ":".
394 The description of the accepted parameters follows.
399 Specify the top left corner coordinates of the logo. They must be
403 Specify the width and height of the logo to clear. They must be
407 Specify the thickness of the fuzzy edge of the rectangle (added to
408 @var{w} and @var{h}). The default value is 4.
411 When set to 1, a green rectangle is drawn on the screen to simplify
412 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
413 @var{band} is set to 4. The default value is 0.
417 Some examples follow.
422 Set a rectangle covering the area with top left corner coordinates 0,0
423 and size 100x77, setting a band of size 10:
429 As the previous example, but use named options:
431 delogo=x=0:y=0:w=100:h=77:band=10
438 Draw a colored box on the input image.
440 It accepts the syntax:
442 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
448 Specify the top left corner coordinates of the box. Default to 0.
451 Specify the width and height of the box, if 0 they are interpreted as
452 the input width and height. Default to 0.
455 Specify the color of the box to write, it can be the name of a color
456 (case insensitive match) or a 0xRRGGBB[AA] sequence.
459 Follow some examples:
461 # draw a black box around the edge of the input image
464 # draw a box with color red and an opacity of 50%
465 drawbox=10:20:200:60:red@@0.5"
470 Draw text string or text from specified file on top of video using the
473 To enable compilation of this filter you need to configure FFmpeg with
474 @code{--enable-libfreetype}.
476 The filter also recognizes strftime() sequences in the provided text
477 and expands them accordingly. Check the documentation of strftime().
479 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
482 The description of the accepted parameters follows.
487 The font file to be used for drawing text. Path must be included.
488 This parameter is mandatory.
491 The text string to be drawn. The text must be a sequence of UTF-8
493 This parameter is mandatory if no file is specified with the parameter
497 A text file containing text to be drawn. The text must be a sequence
498 of UTF-8 encoded characters.
500 This parameter is mandatory if no text string is specified with the
501 parameter @var{text}.
503 If both text and textfile are specified, an error is thrown.
506 The offsets where text will be drawn within the video frame.
507 Relative to the top/left border of the output image.
509 The default value of @var{x} and @var{y} is 0.
512 The font size to be used for drawing text.
513 The default value of @var{fontsize} is 16.
516 The color to be used for drawing fonts.
517 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
518 (e.g. "0xff000033"), possibly followed by an alpha specifier.
519 The default value of @var{fontcolor} is "black".
522 The color to be used for drawing box around text.
523 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
524 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
525 The default value of @var{boxcolor} is "white".
528 Used to draw a box around text using background color.
529 Value should be either 1 (enable) or 0 (disable).
530 The default value of @var{box} is 0.
532 @item shadowx, shadowy
533 The x and y offsets for the text shadow position with respect to the
534 position of the text. They can be either positive or negative
535 values. Default value for both is "0".
538 The color to be used for drawing a shadow behind the drawn text. It
539 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
540 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
541 The default value of @var{shadowcolor} is "black".
544 Flags to be used for loading the fonts.
546 The flags map the corresponding flags supported by libfreetype, and are
547 a combination of the following values:
554 @item vertical_layout
558 @item ignore_global_advance_width
560 @item ignore_transform
567 Default value is "render".
569 For more information consult the documentation for the FT_LOAD_*
573 The size in number of spaces to use for rendering the tab.
577 For example the command:
579 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
582 will draw "Test Text" with font FreeSerif, using the default values
583 for the optional parameters.
587 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
588 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
591 will draw 'Test Text' with font FreeSerif of size 24 at position x=100
592 and y=50 (counting from the top-left corner of the screen), text is
593 yellow with a red box around it. Both the text and the box have an
596 Note that the double quotes are not necessary if spaces are not used
597 within the parameter list.
599 For more information about libfreetype, check:
600 @url{http://www.freetype.org/}.
604 Apply fade-in/out effect to input video.
606 It accepts the parameters:
607 @var{type}:@var{start_frame}:@var{nb_frames}
609 @var{type} specifies if the effect type, can be either "in" for
610 fade-in, or "out" for a fade-out effect.
612 @var{start_frame} specifies the number of the start frame for starting
613 to apply the fade effect.
615 @var{nb_frames} specifies the number of frames for which the fade
616 effect has to last. At the end of the fade-in effect the output video
617 will have the same intensity as the input video, at the end of the
618 fade-out transition the output video will be completely black.
620 A few usage examples follow, usable too as test scenarios.
622 # fade in first 30 frames of video
625 # fade out last 45 frames of a 200-frame video
628 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
629 fade=in:0:25, fade=out:975:25
631 # make first 5 frames black, then fade in from frame 5-24
637 Transform the field order of the input video.
639 It accepts one parameter which specifies the required field order that
640 the input interlaced video will be transformed to. The parameter can
641 assume one of the following values:
645 output bottom field first
647 output top field first
650 Default value is "tff".
652 Transformation is achieved by shifting the picture content up or down
653 by one line, and filling the remaining line with appropriate picture content.
654 This method is consistent with most broadcast field order converters.
656 If the input video is not flagged as being interlaced, or it is already
657 flagged as being of the required output field order then this filter does
658 not alter the incoming video.
660 This filter is very useful when converting to or from PAL DV material,
661 which is bottom field first.
665 ./avconv -i in.vob -vf "fieldorder=bff" out.dv
670 Buffer input images and send them when they are requested.
672 This filter is mainly useful when auto-inserted by the libavfilter
675 The filter does not take parameters.
679 Convert the input video to one of the specified pixel formats.
680 Libavfilter will try to pick one that is supported for the input to
683 The filter accepts a list of pixel format names, separated by ":",
684 for example "yuv420p:monow:rgb24".
686 Some examples follow:
688 # convert the input video to the format "yuv420p"
691 # convert the input video to any of the formats in the list
692 format=yuv420p:yuv444p:yuv410p
698 Apply a frei0r effect to the input video.
700 To enable compilation of this filter you need to install the frei0r
701 header and configure Libav with --enable-frei0r.
703 The filter supports the syntax:
705 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
708 @var{filter_name} is the name to the frei0r effect to load. If the
709 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
710 is searched in each one of the directories specified by the colon
711 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
712 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
713 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
715 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
716 for the frei0r effect.
718 A frei0r effect parameter can be a boolean (whose values are specified
719 with "y" and "n"), a double, a color (specified by the syntax
720 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
721 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
722 description), a position (specified by the syntax @var{X}/@var{Y},
723 @var{X} and @var{Y} being float numbers) and a string.
725 The number and kind of parameters depend on the loaded effect. If an
726 effect parameter is not specified the default value is set.
728 Some examples follow:
730 # apply the distort0r effect, set the first two double parameters
731 frei0r=distort0r:0.5:0.01
733 # apply the colordistance effect, takes a color as first parameter
734 frei0r=colordistance:0.2/0.3/0.4
735 frei0r=colordistance:violet
736 frei0r=colordistance:0x112233
738 # apply the perspective effect, specify the top left and top right
740 frei0r=perspective:0.2/0.2:0.8/0.2
743 For more information see:
744 @url{http://piksel.org/frei0r}
748 Fix the banding artifacts that are sometimes introduced into nearly flat
749 regions by truncation to 8bit colordepth.
750 Interpolate the gradients that should go where the bands are, and
753 This filter is designed for playback only. Do not use it prior to
754 lossy compression, because compression tends to lose the dither and
755 bring back the bands.
757 The filter takes two optional parameters, separated by ':':
758 @var{strength}:@var{radius}
760 @var{strength} is the maximum amount by which the filter will change
761 any one pixel. Also the threshold for detecting nearly flat
762 regions. Acceptable values range from .51 to 255, default value is
763 1.2, out-of-range values will be clipped to the valid range.
765 @var{radius} is the neighborhood to fit the gradient to. A larger
766 radius makes for smoother gradients, but also prevents the filter from
767 modifying the pixels near detailed regions. Acceptable values are
768 8-32, default value is 16, out-of-range values will be clipped to the
781 Flip the input video horizontally.
783 For example to horizontally flip the input video with @command{avconv}:
785 avconv -i in.avi -vf "hflip" out.avi
790 High precision/quality 3d denoise filter. This filter aims to reduce
791 image noise producing smooth images and making still images really
792 still. It should enhance compressibility.
794 It accepts the following optional parameters:
795 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
799 a non-negative float number which specifies spatial luma strength,
803 a non-negative float number which specifies spatial chroma strength,
804 defaults to 3.0*@var{luma_spatial}/4.0
807 a float number which specifies luma temporal strength, defaults to
808 6.0*@var{luma_spatial}/4.0
811 a float number which specifies chroma temporal strength, defaults to
812 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
815 @section lut, lutrgb, lutyuv
817 Compute a look-up table for binding each pixel component input value
818 to an output value, and apply it to input video.
820 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
821 to an RGB input video.
823 These filters accept in input a ":"-separated list of options, which
824 specify the expressions used for computing the lookup table for the
825 corresponding pixel component values.
827 The @var{lut} filter requires either YUV or RGB pixel formats in
828 input, and accepts the options:
830 @var{c0} (first pixel component)
831 @var{c1} (second pixel component)
832 @var{c2} (third pixel component)
833 @var{c3} (fourth pixel component, corresponds to the alpha component)
836 The exact component associated to each option depends on the format in
839 The @var{lutrgb} filter requires RGB pixel formats in input, and
842 @var{r} (red component)
843 @var{g} (green component)
844 @var{b} (blue component)
845 @var{a} (alpha component)
848 The @var{lutyuv} filter requires YUV pixel formats in input, and
851 @var{y} (Y/luminance component)
852 @var{u} (U/Cb component)
853 @var{v} (V/Cr component)
854 @var{a} (alpha component)
857 The expressions can contain the following constants and functions:
861 the corresponding mathematical approximated values for e
862 (euler number), pi (greek PI), PHI (golden ratio)
865 the input width and heigth
868 input value for the pixel component
871 the input value clipped in the @var{minval}-@var{maxval} range
874 maximum value for the pixel component
877 minimum value for the pixel component
880 the negated value for the pixel component value clipped in the
881 @var{minval}-@var{maxval} range , it corresponds to the expression
882 "maxval-clipval+minval"
885 the computed value in @var{val} clipped in the
886 @var{minval}-@var{maxval} range
888 @item gammaval(gamma)
889 the computed gamma correction value of the pixel component value
890 clipped in the @var{minval}-@var{maxval} range, corresponds to the
892 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
896 All expressions default to "val".
898 Some examples follow:
901 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
902 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
904 # the above is the same as
905 lutrgb="r=negval:g=negval:b=negval"
906 lutyuv="y=negval:u=negval:v=negval"
911 # remove chroma components, turns the video into a graytone image
914 # apply a luma burning effect
917 # remove green and blue components
920 # set a constant alpha channel value on input
921 format=rgba,lutrgb=a="maxval-minval/2"
923 # correct luminance gamma by a 0.5 factor
924 lutyuv=y=gammaval(0.5)
931 This filter accepts an integer in input, if non-zero it negates the
932 alpha component (if available). The default value in input is 0.
934 Force libavfilter not to use any of the specified pixel formats for the
935 input to the next filter.
937 The filter accepts a list of pixel format names, separated by ":",
938 for example "yuv420p:monow:rgb24".
940 Some examples follow:
942 # force libavfilter to use a format different from "yuv420p" for the
943 # input to the vflip filter
944 noformat=yuv420p,vflip
946 # convert the input video to any of the formats not contained in the list
947 noformat=yuv420p:yuv444p:yuv410p
952 Pass the video source unchanged to the output.
956 Apply video transform using libopencv.
958 To enable this filter install libopencv library and headers and
959 configure Libav with --enable-libopencv.
961 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
963 @var{filter_name} is the name of the libopencv filter to apply.
965 @var{filter_params} specifies the parameters to pass to the libopencv
966 filter. If not specified the default values are assumed.
968 Refer to the official libopencv documentation for more precise
970 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
972 Follows the list of supported libopencv filters.
977 Dilate an image by using a specific structuring element.
978 This filter corresponds to the libopencv function @code{cvDilate}.
980 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
982 @var{struct_el} represents a structuring element, and has the syntax:
983 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
985 @var{cols} and @var{rows} represent the number of colums and rows of
986 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
987 point, and @var{shape} the shape for the structuring element, and
988 can be one of the values "rect", "cross", "ellipse", "custom".
990 If the value for @var{shape} is "custom", it must be followed by a
991 string of the form "=@var{filename}". The file with name
992 @var{filename} is assumed to represent a binary image, with each
993 printable character corresponding to a bright pixel. When a custom
994 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
995 or columns and rows of the read file are assumed instead.
997 The default value for @var{struct_el} is "3x3+0x0/rect".
999 @var{nb_iterations} specifies the number of times the transform is
1000 applied to the image, and defaults to 1.
1002 Follow some example:
1004 # use the default values
1007 # dilate using a structuring element with a 5x5 cross, iterate two times
1008 ocv=dilate=5x5+2x2/cross:2
1010 # read the shape from the file diamond.shape, iterate two times
1011 # the file diamond.shape may contain a pattern of characters like this:
1017 # the specified cols and rows are ignored (but not the anchor point coordinates)
1018 ocv=0x0+2x2/custom=diamond.shape:2
1023 Erode an image by using a specific structuring element.
1024 This filter corresponds to the libopencv function @code{cvErode}.
1026 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1027 with the same syntax and semantics as the @ref{dilate} filter.
1031 Smooth the input video.
1033 The filter takes the following parameters:
1034 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1036 @var{type} is the type of smooth filter to apply, and can be one of
1037 the following values: "blur", "blur_no_scale", "median", "gaussian",
1038 "bilateral". The default value is "gaussian".
1040 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1041 parameters whose meanings depend on smooth type. @var{param1} and
1042 @var{param2} accept integer positive values or 0, @var{param3} and
1043 @var{param4} accept float values.
1045 The default value for @var{param1} is 3, the default value for the
1046 other parameters is 0.
1048 These parameters correspond to the parameters assigned to the
1049 libopencv function @code{cvSmooth}.
1053 Overlay one video on top of another.
1055 It takes two inputs and one output, the first input is the "main"
1056 video on which the second input is overlayed.
1058 It accepts the parameters: @var{x}:@var{y}.
1060 @var{x} is the x coordinate of the overlayed video on the main video,
1061 @var{y} is the y coordinate. The parameters are expressions containing
1062 the following parameters:
1065 @item main_w, main_h
1066 main input width and height
1069 same as @var{main_w} and @var{main_h}
1071 @item overlay_w, overlay_h
1072 overlay input width and height
1075 same as @var{overlay_w} and @var{overlay_h}
1078 Be aware that frames are taken from each input video in timestamp
1079 order, hence, if their initial timestamps differ, it is a a good idea
1080 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1081 have them begin in the same zero timestamp, as it does the example for
1082 the @var{movie} filter.
1084 Follow some examples:
1086 # draw the overlay at 10 pixels from the bottom right
1087 # corner of the main video.
1088 overlay=main_w-overlay_w-10:main_h-overlay_h-10
1090 # insert a transparent PNG logo in the bottom left corner of the input
1091 movie=logo.png [logo];
1092 [in][logo] overlay=10:main_h-overlay_h-10 [out]
1094 # insert 2 different transparent PNG logos (second logo on bottom
1096 movie=logo1.png [logo1];
1097 movie=logo2.png [logo2];
1098 [in][logo1] overlay=10:H-h-10 [in+logo1];
1099 [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
1101 # add a transparent color layer on top of the main video,
1102 # WxH specifies the size of the main input to the overlay filter
1103 color=red@.3:WxH [over]; [in][over] overlay [out]
1106 You can chain together more overlays but the efficiency of such
1107 approach is yet to be tested.
1111 Add paddings to the input image, and places the original input at the
1112 given coordinates @var{x}, @var{y}.
1114 It accepts the following parameters:
1115 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1117 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1118 expressions containing the following constants:
1122 the corresponding mathematical approximated values for e
1123 (euler number), pi (greek PI), phi (golden ratio)
1126 the input video width and height
1129 same as @var{in_w} and @var{in_h}
1132 the output width and height, that is the size of the padded area as
1133 specified by the @var{width} and @var{height} expressions
1136 same as @var{out_w} and @var{out_h}
1139 x and y offsets as specified by the @var{x} and @var{y}
1140 expressions, or NAN if not yet specified
1143 input display aspect ratio, same as @var{iw} / @var{ih}
1146 horizontal and vertical chroma subsample values. For example for the
1147 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1150 Follows the description of the accepted parameters.
1155 Specify the size of the output image with the paddings added. If the
1156 value for @var{width} or @var{height} is 0, the corresponding input size
1157 is used for the output.
1159 The @var{width} expression can reference the value set by the
1160 @var{height} expression, and viceversa.
1162 The default value of @var{width} and @var{height} is 0.
1166 Specify the offsets where to place the input image in the padded area
1167 with respect to the top/left border of the output image.
1169 The @var{x} expression can reference the value set by the @var{y}
1170 expression, and viceversa.
1172 The default value of @var{x} and @var{y} is 0.
1176 Specify the color of the padded area, it can be the name of a color
1177 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1179 The default value of @var{color} is "black".
1183 Some examples follow:
1186 # Add paddings with color "violet" to the input video. Output video
1187 # size is 640x480, the top-left corner of the input video is placed at
1189 pad=640:480:0:40:violet
1191 # pad the input to get an output with dimensions increased bt 3/2,
1192 # and put the input video at the center of the padded area
1193 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1195 # pad the input to get a squared output with size equal to the maximum
1196 # value between the input width and height, and put the input video at
1197 # the center of the padded area
1198 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1200 # pad the input to get a final w/h ratio of 16:9
1201 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1203 # double output size and put the input video in the bottom-right
1204 # corner of the output padded area
1205 pad="2*iw:2*ih:ow-iw:oh-ih"
1208 @section pixdesctest
1210 Pixel format descriptor test filter, mainly useful for internal
1211 testing. The output video should be equal to the input video.
1215 format=monow, pixdesctest
1218 can be used to test the monowhite pixel format descriptor definition.
1222 Scale the input video to @var{width}:@var{height} and/or convert the image format.
1224 The parameters @var{width} and @var{height} are expressions containing
1225 the following constants:
1229 the corresponding mathematical approximated values for e
1230 (euler number), pi (greek PI), phi (golden ratio)
1233 the input width and height
1236 same as @var{in_w} and @var{in_h}
1239 the output (cropped) width and height
1242 same as @var{out_w} and @var{out_h}
1245 input display aspect ratio, same as @var{iw} / @var{ih}
1248 input sample aspect ratio
1251 horizontal and vertical chroma subsample values. For example for the
1252 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1255 If the input image format is different from the format requested by
1256 the next filter, the scale filter will convert the input to the
1259 If the value for @var{width} or @var{height} is 0, the respective input
1260 size is used for the output.
1262 If the value for @var{width} or @var{height} is -1, the scale filter will
1263 use, for the respective output size, a value that maintains the aspect
1264 ratio of the input image.
1266 The default value of @var{width} and @var{height} is 0.
1268 Some examples follow:
1270 # scale the input video to a size of 200x100.
1273 # scale the input to 2x
1275 # the above is the same as
1278 # scale the input to half size
1281 # increase the width, and set the height to the same size
1284 # seek for Greek harmony
1288 # increase the height, and set the width to 3/2 of the height
1291 # increase the size, but make the size a multiple of the chroma
1292 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1294 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1295 scale='min(500\, iw*3/2):-1'
1299 Select frames to pass in output.
1301 It accepts in input an expression, which is evaluated for each input
1302 frame. If the expression is evaluated to a non-zero value, the frame
1303 is selected and passed to the output, otherwise it is discarded.
1305 The expression can contain the following constants:
1318 the sequential number of the filtered frame, starting from 0
1321 the sequential number of the selected frame, starting from 0
1323 @item prev_selected_n
1324 the sequential number of the last selected frame, NAN if undefined
1327 timebase of the input timestamps
1330 the PTS (Presentation TimeStamp) of the filtered video frame,
1331 expressed in @var{TB} units, NAN if undefined
1334 the PTS (Presentation TimeStamp) of the filtered video frame,
1335 expressed in seconds, NAN if undefined
1338 the PTS of the previously filtered video frame, NAN if undefined
1340 @item prev_selected_pts
1341 the PTS of the last previously filtered video frame, NAN if undefined
1343 @item prev_selected_t
1344 the PTS of the last previously selected video frame, NAN if undefined
1347 the PTS of the first video frame in the video, NAN if undefined
1350 the time of the first video frame in the video, NAN if undefined
1353 the type of the filtered frame, can assume one of the following
1365 @item interlace_type
1366 the frame interlace type, can assume one of the following values:
1369 the frame is progressive (not interlaced)
1371 the frame is top-field-first
1373 the frame is bottom-field-first
1377 1 if the filtered frame is a key-frame, 0 otherwise
1380 the position in the file of the filtered frame, -1 if the information
1381 is not available (e.g. for synthetic video)
1384 The default value of the select expression is "1".
1386 Some examples follow:
1389 # select all frames in input
1392 # the above is the same as:
1398 # select only I-frames
1399 select='eq(pict_type\,I)'
1401 # select one frame every 100
1402 select='not(mod(n\,100))'
1404 # select only frames contained in the 10-20 time interval
1405 select='gte(t\,10)*lte(t\,20)'
1407 # select only I frames contained in the 10-20 time interval
1408 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
1410 # select frames with a minimum distance of 10 seconds
1411 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
1417 Set the Display Aspect Ratio for the filter output video.
1419 This is done by changing the specified Sample (aka Pixel) Aspect
1420 Ratio, according to the following equation:
1421 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1423 Keep in mind that this filter does not modify the pixel dimensions of
1424 the video frame. Also the display aspect ratio set by this filter may
1425 be changed by later filters in the filterchain, e.g. in case of
1426 scaling or if another "setdar" or a "setsar" filter is applied.
1428 The filter accepts a parameter string which represents the wanted
1429 display aspect ratio.
1430 The parameter can be a floating point number string, or an expression
1431 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1432 numerator and denominator of the aspect ratio.
1433 If the parameter is not specified, it is assumed the value "0:1".
1435 For example to change the display aspect ratio to 16:9, specify:
1438 # the above is equivalent to
1442 See also the @ref{setsar} filter documentation.
1446 Change the PTS (presentation timestamp) of the input video frames.
1448 Accept in input an expression evaluated through the eval API, which
1449 can contain the following constants:
1453 the presentation timestamp in input
1465 the count of the input frame, starting from 0.
1468 the PTS of the first video frame
1471 tell if the current frame is interlaced
1474 original position in the file of the frame, or undefined if undefined
1475 for the current frame
1485 Some examples follow:
1488 # start counting PTS from zero
1500 # fixed rate 25 fps with some jitter
1501 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1507 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1509 Note that as a consequence of the application of this filter, the
1510 output display aspect ratio will change according to the following
1512 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1514 Keep in mind that the sample aspect ratio set by this filter may be
1515 changed by later filters in the filterchain, e.g. if another "setsar"
1516 or a "setdar" filter is applied.
1518 The filter accepts a parameter string which represents the wanted
1519 sample aspect ratio.
1520 The parameter can be a floating point number string, or an expression
1521 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1522 numerator and denominator of the aspect ratio.
1523 If the parameter is not specified, it is assumed the value "0:1".
1525 For example to change the sample aspect ratio to 10:11, specify:
1532 Set the timebase to use for the output frames timestamps.
1533 It is mainly useful for testing timebase configuration.
1535 It accepts in input an arithmetic expression representing a rational.
1536 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1537 default timebase), and "intb" (the input timebase).
1539 The default value for the input is "intb".
1541 Follow some examples.
1544 # set the timebase to 1/25
1547 # set the timebase to 1/10
1550 #set the timebase to 1001/1000
1553 #set the timebase to 2*intb
1556 #set the default timebase value
1562 Show a line containing various information for each input video frame.
1563 The input video is not modified.
1565 The shown line contains a sequence of key/value pairs of the form
1566 @var{key}:@var{value}.
1568 A description of each shown parameter follows:
1572 sequential number of the input frame, starting from 0
1575 Presentation TimeStamp of the input frame, expressed as a number of
1576 time base units. The time base unit depends on the filter input pad.
1579 Presentation TimeStamp of the input frame, expressed as a number of
1583 position of the frame in the input stream, -1 if this information in
1584 unavailable and/or meanigless (for example in case of synthetic video)
1590 sample aspect ratio of the input frame, expressed in the form
1594 size of the input frame, expressed in the form
1595 @var{width}x@var{height}
1598 interlaced mode ("P" for "progressive", "T" for top field first, "B"
1599 for bottom field first)
1602 1 if the frame is a key frame, 0 otherwise
1605 picture type of the input frame ("I" for an I-frame, "P" for a
1606 P-frame, "B" for a B-frame, "?" for unknown type).
1607 Check also the documentation of the @code{AVPictureType} enum and of
1608 the @code{av_get_picture_type_char} function defined in
1609 @file{libavutil/avutil.h}.
1612 Adler-32 checksum of all the planes of the input frame
1614 @item plane_checksum
1615 Adler-32 checksum of each plane of the input frame, expressed in the form
1616 "[@var{c0} @var{c1} @var{c2} @var{c3}]"
1621 Pass the images of input video on to next video filter as multiple
1625 ./avconv -i in.avi -vf "slicify=32" out.avi
1628 The filter accepts the slice height as parameter. If the parameter is
1629 not specified it will use the default value of 16.
1631 Adding this in the beginning of filter chains should make filtering
1632 faster due to better use of the memory cache.
1636 Transpose rows with columns in the input video and optionally flip it.
1638 It accepts a parameter representing an integer, which can assume the
1643 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1651 Rotate by 90 degrees clockwise, that is:
1659 Rotate by 90 degrees counterclockwise, that is:
1667 Rotate by 90 degrees clockwise and vertically flip, that is:
1677 Sharpen or blur the input video.
1679 It accepts the following parameters:
1680 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1682 Negative values for the amount will blur the input video, while positive
1683 values will sharpen. All parameters are optional and default to the
1684 equivalent of the string '5:5:1.0:5:5:0.0'.
1689 Set the luma matrix horizontal size. It can be an integer between 3
1690 and 13, default value is 5.
1693 Set the luma matrix vertical size. It can be an integer between 3
1694 and 13, default value is 5.
1697 Set the luma effect strength. It can be a float number between -2.0
1698 and 5.0, default value is 1.0.
1700 @item chroma_msize_x
1701 Set the chroma matrix horizontal size. It can be an integer between 3
1702 and 13, default value is 5.
1704 @item chroma_msize_y
1705 Set the chroma matrix vertical size. It can be an integer between 3
1706 and 13, default value is 5.
1709 Set the chroma effect strength. It can be a float number between -2.0
1710 and 5.0, default value is 0.0.
1715 # Strong luma sharpen effect parameters
1718 # Strong blur of both luma and chroma parameters
1719 unsharp=7:7:-2:7:7:-2
1721 # Use the default values with @command{avconv}
1722 ./avconv -i in.avi -vf "unsharp" out.mp4
1727 Flip the input video vertically.
1730 ./avconv -i in.avi -vf "vflip" out.avi
1735 Deinterlace the input video ("yadif" means "yet another deinterlacing
1738 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
1740 @var{mode} specifies the interlacing mode to adopt, accepts one of the
1745 output 1 frame for each frame
1747 output 1 frame for each field
1749 like 0 but skips spatial interlacing check
1751 like 1 but skips spatial interlacing check
1756 @var{parity} specifies the picture field parity assumed for the input
1757 interlaced video, accepts one of the following values:
1761 assume top field first
1763 assume bottom field first
1765 enable automatic detection
1768 Default value is -1.
1769 If interlacing is unknown or decoder does not export this information,
1770 top field first will be assumed.
1772 @var{auto} specifies if deinterlacer should trust the interlaced flag
1773 and only deinterlace frames marked as interlaced
1777 deinterlace all frames
1779 only deinterlace frames marked as interlaced
1784 @c man end VIDEO FILTERS
1786 @chapter Video Sources
1787 @c man begin VIDEO SOURCES
1789 Below is a description of the currently available video sources.
1793 Buffer video frames, and make them available to the filter chain.
1795 This source is mainly intended for a programmatic use, in particular
1796 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1798 It accepts the following parameters:
1799 @var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1801 All the parameters need to be explicitely defined.
1803 Follows the list of the accepted parameters.
1808 Specify the width and height of the buffered video frames.
1810 @item pix_fmt_string
1811 A string representing the pixel format of the buffered video frames.
1812 It may be a number corresponding to a pixel format, or a pixel format
1815 @item timebase_num, timebase_den
1816 Specify numerator and denomitor of the timebase assumed by the
1817 timestamps of the buffered frames.
1819 @item sample_aspect_ratio.num, sample_aspect_ratio.den
1820 Specify numerator and denominator of the sample aspect ratio assumed
1821 by the video frames.
1826 buffer=320:240:yuv410p:1:24:1:1
1829 will instruct the source to accept video frames with size 320x240 and
1830 with format "yuv410p", assuming 1/24 as the timestamps timebase and
1831 square pixels (1:1 sample aspect ratio).
1832 Since the pixel format with name "yuv410p" corresponds to the number 6
1833 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1834 this example corresponds to:
1836 buffer=320:240:6:1:24
1841 Provide an uniformly colored input.
1843 It accepts the following parameters:
1844 @var{color}:@var{frame_size}:@var{frame_rate}
1846 Follows the description of the accepted parameters.
1851 Specify the color of the source. It can be the name of a color (case
1852 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1853 alpha specifier. The default value is "black".
1856 Specify the size of the sourced video, it may be a string of the form
1857 @var{width}x@var{height}, or the name of a size abbreviation. The
1858 default value is "320x240".
1861 Specify the frame rate of the sourced video, as the number of frames
1862 generated per second. It has to be a string in the format
1863 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1864 number or a valid video frame rate abbreviation. The default value is
1869 For example the following graph description will generate a red source
1870 with an opacity of 0.2, with size "qcif" and a frame rate of 10
1871 frames per second, which will be overlayed over the source connected
1872 to the pad with identifier "in".
1875 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1880 Read a video stream from a movie container.
1882 It accepts the syntax: @var{movie_name}[:@var{options}] where
1883 @var{movie_name} is the name of the resource to read (not necessarily
1884 a file but also a device or a stream accessed through some protocol),
1885 and @var{options} is an optional sequence of @var{key}=@var{value}
1886 pairs, separated by ":".
1888 The description of the accepted options follows.
1892 @item format_name, f
1893 Specifies the format assumed for the movie to read, and can be either
1894 the name of a container or an input device. If not specified the
1895 format is guessed from @var{movie_name} or by probing.
1897 @item seek_point, sp
1898 Specifies the seek point in seconds, the frames will be output
1899 starting from this seek point, the parameter is evaluated with
1900 @code{av_strtod} so the numerical value may be suffixed by an IS
1901 postfix. Default value is "0".
1903 @item stream_index, si
1904 Specifies the index of the video stream to read. If the value is -1,
1905 the best suited video stream will be automatically selected. Default
1910 This filter allows to overlay a second video on top of main input of
1911 a filtergraph as shown in this graph:
1913 input -----------> deltapts0 --> overlay --> output
1916 movie --> scale--> deltapts1 -------+
1919 Some examples follow:
1921 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1922 # on top of the input labelled as "in".
1923 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1924 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1926 # read from a video4linux2 device, and overlay it on top of the input
1928 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1929 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1935 Null video source, never return images. It is mainly useful as a
1936 template and to be employed in analysis / debugging tools.
1938 It accepts as optional parameter a string of the form
1939 @var{width}:@var{height}:@var{timebase}.
1941 @var{width} and @var{height} specify the size of the configured
1942 source. The default values of @var{width} and @var{height} are
1943 respectively 352 and 288 (corresponding to the CIF size format).
1945 @var{timebase} specifies an arithmetic expression representing a
1946 timebase. The expression can contain the constants "PI", "E", "PHI",
1947 "AVTB" (the default timebase), and defaults to the value "AVTB".
1951 Provide a frei0r source.
1953 To enable compilation of this filter you need to install the frei0r
1954 header and configure Libav with --enable-frei0r.
1956 The source supports the syntax:
1958 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1961 @var{size} is the size of the video to generate, may be a string of the
1962 form @var{width}x@var{height} or a frame size abbreviation.
1963 @var{rate} is the rate of the video to generate, may be a string of
1964 the form @var{num}/@var{den} or a frame rate abbreviation.
1965 @var{src_name} is the name to the frei0r source to load. For more
1966 information regarding frei0r and how to set the parameters read the
1967 section @ref{frei0r} in the description of the video filters.
1969 Some examples follow:
1971 # generate a frei0r partik0l source with size 200x200 and framerate 10
1972 # which is overlayed on the overlay filter main input
1973 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
1976 @section rgbtestsrc, testsrc
1978 The @code{rgbtestsrc} source generates an RGB test pattern useful for
1979 detecting RGB vs BGR issues. You should see a red, green and blue
1980 stripe from top to bottom.
1982 The @code{testsrc} source generates a test video pattern, showing a
1983 color pattern, a scrolling gradient and a timestamp. This is mainly
1984 intended for testing purposes.
1986 Both sources accept an optional sequence of @var{key}=@var{value} pairs,
1987 separated by ":". The description of the accepted options follows.
1992 Specify the size of the sourced video, it may be a string of the form
1993 @var{width}x@var{heigth}, or the name of a size abbreviation. The
1994 default value is "320x240".
1997 Specify the frame rate of the sourced video, as the number of frames
1998 generated per second. It has to be a string in the format
1999 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2000 number or a valid video frame rate abbreviation. The default value is
2004 Set the sample aspect ratio of the sourced video.
2007 Set the video duration of the sourced video. The accepted syntax is:
2009 [-]HH[:MM[:SS[.m...]]]
2012 See also the function @code{av_parse_time()}.
2014 If not specified, or the expressed duration is negative, the video is
2015 supposed to be generated forever.
2018 For example the following:
2020 testsrc=duration=5.3:size=qcif:rate=10
2023 will generate a video with a duration of 5.3 seconds, with size
2024 176x144 and a framerate of 10 frames per second.
2026 @c man end VIDEO SOURCES
2028 @chapter Video Sinks
2029 @c man begin VIDEO SINKS
2031 Below is a description of the currently available video sinks.
2035 Null video sink, do absolutely nothing with the input video. It is
2036 mainly useful as a template and to be employed in analysis / debugging
2039 @c man end VIDEO SINKS