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 height 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.
508 They accept expressions similar to the @ref{overlay} filter:
512 the computed values for @var{x} and @var{y}. They are evaluated for
516 main input width and height
519 same as @var{main_w} and @var{main_h}
522 rendered text width and height
525 same as @var{text_w} and @var{text_h}
528 the number of frames processed, starting from 0
531 timestamp expressed in seconds, NAN if the input timestamp is unknown
535 The default value of @var{x} and @var{y} is 0.
538 The font size to be used for drawing text.
539 The default value of @var{fontsize} is 16.
542 The color to be used for drawing fonts.
543 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
544 (e.g. "0xff000033"), possibly followed by an alpha specifier.
545 The default value of @var{fontcolor} is "black".
548 The color to be used for drawing box around text.
549 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
550 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
551 The default value of @var{boxcolor} is "white".
554 Used to draw a box around text using background color.
555 Value should be either 1 (enable) or 0 (disable).
556 The default value of @var{box} is 0.
558 @item shadowx, shadowy
559 The x and y offsets for the text shadow position with respect to the
560 position of the text. They can be either positive or negative
561 values. Default value for both is "0".
564 The color to be used for drawing a shadow behind the drawn text. It
565 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
566 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
567 The default value of @var{shadowcolor} is "black".
570 Flags to be used for loading the fonts.
572 The flags map the corresponding flags supported by libfreetype, and are
573 a combination of the following values:
580 @item vertical_layout
584 @item ignore_global_advance_width
586 @item ignore_transform
593 Default value is "render".
595 For more information consult the documentation for the FT_LOAD_*
599 The size in number of spaces to use for rendering the tab.
603 For example the command:
605 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
608 will draw "Test Text" with font FreeSerif, using the default values
609 for the optional parameters.
613 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
614 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
617 will draw 'Test Text' with font FreeSerif of size 24 at position x=100
618 and y=50 (counting from the top-left corner of the screen), text is
619 yellow with a red box around it. Both the text and the box have an
622 Note that the double quotes are not necessary if spaces are not used
623 within the parameter list.
625 For more information about libfreetype, check:
626 @url{http://www.freetype.org/}.
630 Apply fade-in/out effect to input video.
632 It accepts the parameters:
633 @var{type}:@var{start_frame}:@var{nb_frames}
635 @var{type} specifies if the effect type, can be either "in" for
636 fade-in, or "out" for a fade-out effect.
638 @var{start_frame} specifies the number of the start frame for starting
639 to apply the fade effect.
641 @var{nb_frames} specifies the number of frames for which the fade
642 effect has to last. At the end of the fade-in effect the output video
643 will have the same intensity as the input video, at the end of the
644 fade-out transition the output video will be completely black.
646 A few usage examples follow, usable too as test scenarios.
648 # fade in first 30 frames of video
651 # fade out last 45 frames of a 200-frame video
654 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
655 fade=in:0:25, fade=out:975:25
657 # make first 5 frames black, then fade in from frame 5-24
663 Transform the field order of the input video.
665 It accepts one parameter which specifies the required field order that
666 the input interlaced video will be transformed to. The parameter can
667 assume one of the following values:
671 output bottom field first
673 output top field first
676 Default value is "tff".
678 Transformation is achieved by shifting the picture content up or down
679 by one line, and filling the remaining line with appropriate picture content.
680 This method is consistent with most broadcast field order converters.
682 If the input video is not flagged as being interlaced, or it is already
683 flagged as being of the required output field order then this filter does
684 not alter the incoming video.
686 This filter is very useful when converting to or from PAL DV material,
687 which is bottom field first.
691 ./avconv -i in.vob -vf "fieldorder=bff" out.dv
696 Buffer input images and send them when they are requested.
698 This filter is mainly useful when auto-inserted by the libavfilter
701 The filter does not take parameters.
705 Convert the input video to one of the specified pixel formats.
706 Libavfilter will try to pick one that is supported for the input to
709 The filter accepts a list of pixel format names, separated by ":",
710 for example "yuv420p:monow:rgb24".
712 Some examples follow:
714 # convert the input video to the format "yuv420p"
717 # convert the input video to any of the formats in the list
718 format=yuv420p:yuv444p:yuv410p
724 Apply a frei0r effect to the input video.
726 To enable compilation of this filter you need to install the frei0r
727 header and configure Libav with --enable-frei0r.
729 The filter supports the syntax:
731 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
734 @var{filter_name} is the name to the frei0r effect to load. If the
735 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
736 is searched in each one of the directories specified by the colon
737 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
738 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
739 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
741 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
742 for the frei0r effect.
744 A frei0r effect parameter can be a boolean (whose values are specified
745 with "y" and "n"), a double, a color (specified by the syntax
746 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
747 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
748 description), a position (specified by the syntax @var{X}/@var{Y},
749 @var{X} and @var{Y} being float numbers) and a string.
751 The number and kind of parameters depend on the loaded effect. If an
752 effect parameter is not specified the default value is set.
754 Some examples follow:
756 # apply the distort0r effect, set the first two double parameters
757 frei0r=distort0r:0.5:0.01
759 # apply the colordistance effect, takes a color as first parameter
760 frei0r=colordistance:0.2/0.3/0.4
761 frei0r=colordistance:violet
762 frei0r=colordistance:0x112233
764 # apply the perspective effect, specify the top left and top right
766 frei0r=perspective:0.2/0.2:0.8/0.2
769 For more information see:
770 @url{http://piksel.org/frei0r}
774 Fix the banding artifacts that are sometimes introduced into nearly flat
775 regions by truncation to 8bit colordepth.
776 Interpolate the gradients that should go where the bands are, and
779 This filter is designed for playback only. Do not use it prior to
780 lossy compression, because compression tends to lose the dither and
781 bring back the bands.
783 The filter takes two optional parameters, separated by ':':
784 @var{strength}:@var{radius}
786 @var{strength} is the maximum amount by which the filter will change
787 any one pixel. Also the threshold for detecting nearly flat
788 regions. Acceptable values range from .51 to 255, default value is
789 1.2, out-of-range values will be clipped to the valid range.
791 @var{radius} is the neighborhood to fit the gradient to. A larger
792 radius makes for smoother gradients, but also prevents the filter from
793 modifying the pixels near detailed regions. Acceptable values are
794 8-32, default value is 16, out-of-range values will be clipped to the
807 Flip the input video horizontally.
809 For example to horizontally flip the input video with @command{avconv}:
811 avconv -i in.avi -vf "hflip" out.avi
816 High precision/quality 3d denoise filter. This filter aims to reduce
817 image noise producing smooth images and making still images really
818 still. It should enhance compressibility.
820 It accepts the following optional parameters:
821 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
825 a non-negative float number which specifies spatial luma strength,
829 a non-negative float number which specifies spatial chroma strength,
830 defaults to 3.0*@var{luma_spatial}/4.0
833 a float number which specifies luma temporal strength, defaults to
834 6.0*@var{luma_spatial}/4.0
837 a float number which specifies chroma temporal strength, defaults to
838 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
841 @section lut, lutrgb, lutyuv
843 Compute a look-up table for binding each pixel component input value
844 to an output value, and apply it to input video.
846 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
847 to an RGB input video.
849 These filters accept in input a ":"-separated list of options, which
850 specify the expressions used for computing the lookup table for the
851 corresponding pixel component values.
853 The @var{lut} filter requires either YUV or RGB pixel formats in
854 input, and accepts the options:
856 @var{c0} (first pixel component)
857 @var{c1} (second pixel component)
858 @var{c2} (third pixel component)
859 @var{c3} (fourth pixel component, corresponds to the alpha component)
862 The exact component associated to each option depends on the format in
865 The @var{lutrgb} filter requires RGB pixel formats in input, and
868 @var{r} (red component)
869 @var{g} (green component)
870 @var{b} (blue component)
871 @var{a} (alpha component)
874 The @var{lutyuv} filter requires YUV pixel formats in input, and
877 @var{y} (Y/luminance component)
878 @var{u} (U/Cb component)
879 @var{v} (V/Cr component)
880 @var{a} (alpha component)
883 The expressions can contain the following constants and functions:
887 the corresponding mathematical approximated values for e
888 (euler number), pi (greek PI), PHI (golden ratio)
891 the input width and height
894 input value for the pixel component
897 the input value clipped in the @var{minval}-@var{maxval} range
900 maximum value for the pixel component
903 minimum value for the pixel component
906 the negated value for the pixel component value clipped in the
907 @var{minval}-@var{maxval} range , it corresponds to the expression
908 "maxval-clipval+minval"
911 the computed value in @var{val} clipped in the
912 @var{minval}-@var{maxval} range
914 @item gammaval(gamma)
915 the computed gamma correction value of the pixel component value
916 clipped in the @var{minval}-@var{maxval} range, corresponds to the
918 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
922 All expressions default to "val".
924 Some examples follow:
927 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
928 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
930 # the above is the same as
931 lutrgb="r=negval:g=negval:b=negval"
932 lutyuv="y=negval:u=negval:v=negval"
937 # remove chroma components, turns the video into a graytone image
940 # apply a luma burning effect
943 # remove green and blue components
946 # set a constant alpha channel value on input
947 format=rgba,lutrgb=a="maxval-minval/2"
949 # correct luminance gamma by a 0.5 factor
950 lutyuv=y=gammaval(0.5)
957 This filter accepts an integer in input, if non-zero it negates the
958 alpha component (if available). The default value in input is 0.
960 Force libavfilter not to use any of the specified pixel formats for the
961 input to the next filter.
963 The filter accepts a list of pixel format names, separated by ":",
964 for example "yuv420p:monow:rgb24".
966 Some examples follow:
968 # force libavfilter to use a format different from "yuv420p" for the
969 # input to the vflip filter
970 noformat=yuv420p,vflip
972 # convert the input video to any of the formats not contained in the list
973 noformat=yuv420p:yuv444p:yuv410p
978 Pass the video source unchanged to the output.
982 Apply video transform using libopencv.
984 To enable this filter install libopencv library and headers and
985 configure Libav with --enable-libopencv.
987 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
989 @var{filter_name} is the name of the libopencv filter to apply.
991 @var{filter_params} specifies the parameters to pass to the libopencv
992 filter. If not specified the default values are assumed.
994 Refer to the official libopencv documentation for more precise
996 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
998 Follows the list of supported libopencv filters.
1003 Dilate an image by using a specific structuring element.
1004 This filter corresponds to the libopencv function @code{cvDilate}.
1006 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1008 @var{struct_el} represents a structuring element, and has the syntax:
1009 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1011 @var{cols} and @var{rows} represent the number of columns and rows of
1012 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1013 point, and @var{shape} the shape for the structuring element, and
1014 can be one of the values "rect", "cross", "ellipse", "custom".
1016 If the value for @var{shape} is "custom", it must be followed by a
1017 string of the form "=@var{filename}". The file with name
1018 @var{filename} is assumed to represent a binary image, with each
1019 printable character corresponding to a bright pixel. When a custom
1020 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1021 or columns and rows of the read file are assumed instead.
1023 The default value for @var{struct_el} is "3x3+0x0/rect".
1025 @var{nb_iterations} specifies the number of times the transform is
1026 applied to the image, and defaults to 1.
1028 Follow some example:
1030 # use the default values
1033 # dilate using a structuring element with a 5x5 cross, iterate two times
1034 ocv=dilate=5x5+2x2/cross:2
1036 # read the shape from the file diamond.shape, iterate two times
1037 # the file diamond.shape may contain a pattern of characters like this:
1043 # the specified cols and rows are ignored (but not the anchor point coordinates)
1044 ocv=0x0+2x2/custom=diamond.shape:2
1049 Erode an image by using a specific structuring element.
1050 This filter corresponds to the libopencv function @code{cvErode}.
1052 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1053 with the same syntax and semantics as the @ref{dilate} filter.
1057 Smooth the input video.
1059 The filter takes the following parameters:
1060 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1062 @var{type} is the type of smooth filter to apply, and can be one of
1063 the following values: "blur", "blur_no_scale", "median", "gaussian",
1064 "bilateral". The default value is "gaussian".
1066 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1067 parameters whose meanings depend on smooth type. @var{param1} and
1068 @var{param2} accept integer positive values or 0, @var{param3} and
1069 @var{param4} accept float values.
1071 The default value for @var{param1} is 3, the default value for the
1072 other parameters is 0.
1074 These parameters correspond to the parameters assigned to the
1075 libopencv function @code{cvSmooth}.
1080 Overlay one video on top of another.
1082 It takes two inputs and one output, the first input is the "main"
1083 video on which the second input is overlayed.
1085 It accepts the parameters: @var{x}:@var{y}.
1087 @var{x} is the x coordinate of the overlayed video on the main video,
1088 @var{y} is the y coordinate. The parameters are expressions containing
1089 the following parameters:
1092 @item main_w, main_h
1093 main input width and height
1096 same as @var{main_w} and @var{main_h}
1098 @item overlay_w, overlay_h
1099 overlay input width and height
1102 same as @var{overlay_w} and @var{overlay_h}
1105 Be aware that frames are taken from each input video in timestamp
1106 order, hence, if their initial timestamps differ, it is a a good idea
1107 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1108 have them begin in the same zero timestamp, as it does the example for
1109 the @var{movie} filter.
1111 Follow some examples:
1113 # draw the overlay at 10 pixels from the bottom right
1114 # corner of the main video.
1115 overlay=main_w-overlay_w-10:main_h-overlay_h-10
1117 # insert a transparent PNG logo in the bottom left corner of the input
1118 movie=logo.png [logo];
1119 [in][logo] overlay=10:main_h-overlay_h-10 [out]
1121 # insert 2 different transparent PNG logos (second logo on bottom
1123 movie=logo1.png [logo1];
1124 movie=logo2.png [logo2];
1125 [in][logo1] overlay=10:H-h-10 [in+logo1];
1126 [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
1128 # add a transparent color layer on top of the main video,
1129 # WxH specifies the size of the main input to the overlay filter
1130 color=red@.3:WxH [over]; [in][over] overlay [out]
1133 You can chain together more overlays but the efficiency of such
1134 approach is yet to be tested.
1138 Add paddings to the input image, and places the original input at the
1139 given coordinates @var{x}, @var{y}.
1141 It accepts the following parameters:
1142 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1144 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1145 expressions containing the following constants:
1149 the corresponding mathematical approximated values for e
1150 (euler number), pi (greek PI), phi (golden ratio)
1153 the input video width and height
1156 same as @var{in_w} and @var{in_h}
1159 the output width and height, that is the size of the padded area as
1160 specified by the @var{width} and @var{height} expressions
1163 same as @var{out_w} and @var{out_h}
1166 x and y offsets as specified by the @var{x} and @var{y}
1167 expressions, or NAN if not yet specified
1170 input display aspect ratio, same as @var{iw} / @var{ih}
1173 horizontal and vertical chroma subsample values. For example for the
1174 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1177 Follows the description of the accepted parameters.
1182 Specify the size of the output image with the paddings added. If the
1183 value for @var{width} or @var{height} is 0, the corresponding input size
1184 is used for the output.
1186 The @var{width} expression can reference the value set by the
1187 @var{height} expression, and vice versa.
1189 The default value of @var{width} and @var{height} is 0.
1193 Specify the offsets where to place the input image in the padded area
1194 with respect to the top/left border of the output image.
1196 The @var{x} expression can reference the value set by the @var{y}
1197 expression, and vice versa.
1199 The default value of @var{x} and @var{y} is 0.
1203 Specify the color of the padded area, it can be the name of a color
1204 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1206 The default value of @var{color} is "black".
1210 Some examples follow:
1213 # Add paddings with color "violet" to the input video. Output video
1214 # size is 640x480, the top-left corner of the input video is placed at
1216 pad=640:480:0:40:violet
1218 # pad the input to get an output with dimensions increased bt 3/2,
1219 # and put the input video at the center of the padded area
1220 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1222 # pad the input to get a squared output with size equal to the maximum
1223 # value between the input width and height, and put the input video at
1224 # the center of the padded area
1225 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1227 # pad the input to get a final w/h ratio of 16:9
1228 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1230 # double output size and put the input video in the bottom-right
1231 # corner of the output padded area
1232 pad="2*iw:2*ih:ow-iw:oh-ih"
1235 @section pixdesctest
1237 Pixel format descriptor test filter, mainly useful for internal
1238 testing. The output video should be equal to the input video.
1242 format=monow, pixdesctest
1245 can be used to test the monowhite pixel format descriptor definition.
1249 Scale the input video to @var{width}:@var{height} and/or convert the image format.
1251 The parameters @var{width} and @var{height} are expressions containing
1252 the following constants:
1256 the corresponding mathematical approximated values for e
1257 (euler number), pi (greek PI), phi (golden ratio)
1260 the input width and height
1263 same as @var{in_w} and @var{in_h}
1266 the output (cropped) width and height
1269 same as @var{out_w} and @var{out_h}
1272 input display aspect ratio, same as @var{iw} / @var{ih}
1275 input sample aspect ratio
1278 horizontal and vertical chroma subsample values. For example for the
1279 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1282 If the input image format is different from the format requested by
1283 the next filter, the scale filter will convert the input to the
1286 If the value for @var{width} or @var{height} is 0, the respective input
1287 size is used for the output.
1289 If the value for @var{width} or @var{height} is -1, the scale filter will
1290 use, for the respective output size, a value that maintains the aspect
1291 ratio of the input image.
1293 The default value of @var{width} and @var{height} is 0.
1295 Some examples follow:
1297 # scale the input video to a size of 200x100.
1300 # scale the input to 2x
1302 # the above is the same as
1305 # scale the input to half size
1308 # increase the width, and set the height to the same size
1311 # seek for Greek harmony
1315 # increase the height, and set the width to 3/2 of the height
1318 # increase the size, but make the size a multiple of the chroma
1319 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1321 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1322 scale='min(500\, iw*3/2):-1'
1326 Select frames to pass in output.
1328 It accepts in input an expression, which is evaluated for each input
1329 frame. If the expression is evaluated to a non-zero value, the frame
1330 is selected and passed to the output, otherwise it is discarded.
1332 The expression can contain the following constants:
1345 the sequential number of the filtered frame, starting from 0
1348 the sequential number of the selected frame, starting from 0
1350 @item prev_selected_n
1351 the sequential number of the last selected frame, NAN if undefined
1354 timebase of the input timestamps
1357 the PTS (Presentation TimeStamp) of the filtered video frame,
1358 expressed in @var{TB} units, NAN if undefined
1361 the PTS (Presentation TimeStamp) of the filtered video frame,
1362 expressed in seconds, NAN if undefined
1365 the PTS of the previously filtered video frame, NAN if undefined
1367 @item prev_selected_pts
1368 the PTS of the last previously filtered video frame, NAN if undefined
1370 @item prev_selected_t
1371 the PTS of the last previously selected video frame, NAN if undefined
1374 the PTS of the first video frame in the video, NAN if undefined
1377 the time of the first video frame in the video, NAN if undefined
1380 the type of the filtered frame, can assume one of the following
1392 @item interlace_type
1393 the frame interlace type, can assume one of the following values:
1396 the frame is progressive (not interlaced)
1398 the frame is top-field-first
1400 the frame is bottom-field-first
1404 1 if the filtered frame is a key-frame, 0 otherwise
1407 the position in the file of the filtered frame, -1 if the information
1408 is not available (e.g. for synthetic video)
1411 The default value of the select expression is "1".
1413 Some examples follow:
1416 # select all frames in input
1419 # the above is the same as:
1425 # select only I-frames
1426 select='eq(pict_type\,I)'
1428 # select one frame every 100
1429 select='not(mod(n\,100))'
1431 # select only frames contained in the 10-20 time interval
1432 select='gte(t\,10)*lte(t\,20)'
1434 # select only I frames contained in the 10-20 time interval
1435 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
1437 # select frames with a minimum distance of 10 seconds
1438 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
1444 Set the Display Aspect Ratio for the filter output video.
1446 This is done by changing the specified Sample (aka Pixel) Aspect
1447 Ratio, according to the following equation:
1448 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1450 Keep in mind that this filter does not modify the pixel dimensions of
1451 the video frame. Also the display aspect ratio set by this filter may
1452 be changed by later filters in the filterchain, e.g. in case of
1453 scaling or if another "setdar" or a "setsar" filter is applied.
1455 The filter accepts a parameter string which represents the wanted
1456 display aspect ratio.
1457 The parameter can be a floating point number string, or an expression
1458 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1459 numerator and denominator of the aspect ratio.
1460 If the parameter is not specified, it is assumed the value "0:1".
1462 For example to change the display aspect ratio to 16:9, specify:
1465 # the above is equivalent to
1469 See also the @ref{setsar} filter documentation.
1473 Change the PTS (presentation timestamp) of the input video frames.
1475 Accept in input an expression evaluated through the eval API, which
1476 can contain the following constants:
1480 the presentation timestamp in input
1492 the count of the input frame, starting from 0.
1495 the PTS of the first video frame
1498 tell if the current frame is interlaced
1501 original position in the file of the frame, or undefined if undefined
1502 for the current frame
1512 Some examples follow:
1515 # start counting PTS from zero
1527 # fixed rate 25 fps with some jitter
1528 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1534 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1536 Note that as a consequence of the application of this filter, the
1537 output display aspect ratio will change according to the following
1539 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1541 Keep in mind that the sample aspect ratio set by this filter may be
1542 changed by later filters in the filterchain, e.g. if another "setsar"
1543 or a "setdar" filter is applied.
1545 The filter accepts a parameter string which represents the wanted
1546 sample aspect ratio.
1547 The parameter can be a floating point number string, or an expression
1548 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1549 numerator and denominator of the aspect ratio.
1550 If the parameter is not specified, it is assumed the value "0:1".
1552 For example to change the sample aspect ratio to 10:11, specify:
1559 Set the timebase to use for the output frames timestamps.
1560 It is mainly useful for testing timebase configuration.
1562 It accepts in input an arithmetic expression representing a rational.
1563 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1564 default timebase), and "intb" (the input timebase).
1566 The default value for the input is "intb".
1568 Follow some examples.
1571 # set the timebase to 1/25
1574 # set the timebase to 1/10
1577 #set the timebase to 1001/1000
1580 #set the timebase to 2*intb
1583 #set the default timebase value
1589 Show a line containing various information for each input video frame.
1590 The input video is not modified.
1592 The shown line contains a sequence of key/value pairs of the form
1593 @var{key}:@var{value}.
1595 A description of each shown parameter follows:
1599 sequential number of the input frame, starting from 0
1602 Presentation TimeStamp of the input frame, expressed as a number of
1603 time base units. The time base unit depends on the filter input pad.
1606 Presentation TimeStamp of the input frame, expressed as a number of
1610 position of the frame in the input stream, -1 if this information in
1611 unavailable and/or meaningless (for example in case of synthetic video)
1617 sample aspect ratio of the input frame, expressed in the form
1621 size of the input frame, expressed in the form
1622 @var{width}x@var{height}
1625 interlaced mode ("P" for "progressive", "T" for top field first, "B"
1626 for bottom field first)
1629 1 if the frame is a key frame, 0 otherwise
1632 picture type of the input frame ("I" for an I-frame, "P" for a
1633 P-frame, "B" for a B-frame, "?" for unknown type).
1634 Check also the documentation of the @code{AVPictureType} enum and of
1635 the @code{av_get_picture_type_char} function defined in
1636 @file{libavutil/avutil.h}.
1639 Adler-32 checksum of all the planes of the input frame
1641 @item plane_checksum
1642 Adler-32 checksum of each plane of the input frame, expressed in the form
1643 "[@var{c0} @var{c1} @var{c2} @var{c3}]"
1648 Pass the images of input video on to next video filter as multiple
1652 ./avconv -i in.avi -vf "slicify=32" out.avi
1655 The filter accepts the slice height as parameter. If the parameter is
1656 not specified it will use the default value of 16.
1658 Adding this in the beginning of filter chains should make filtering
1659 faster due to better use of the memory cache.
1663 Transpose rows with columns in the input video and optionally flip it.
1665 It accepts a parameter representing an integer, which can assume the
1670 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1678 Rotate by 90 degrees clockwise, that is:
1686 Rotate by 90 degrees counterclockwise, that is:
1694 Rotate by 90 degrees clockwise and vertically flip, that is:
1704 Sharpen or blur the input video.
1706 It accepts the following parameters:
1707 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1709 Negative values for the amount will blur the input video, while positive
1710 values will sharpen. All parameters are optional and default to the
1711 equivalent of the string '5:5:1.0:5:5:0.0'.
1716 Set the luma matrix horizontal size. It can be an integer between 3
1717 and 13, default value is 5.
1720 Set the luma matrix vertical size. It can be an integer between 3
1721 and 13, default value is 5.
1724 Set the luma effect strength. It can be a float number between -2.0
1725 and 5.0, default value is 1.0.
1727 @item chroma_msize_x
1728 Set the chroma matrix horizontal size. It can be an integer between 3
1729 and 13, default value is 5.
1731 @item chroma_msize_y
1732 Set the chroma matrix vertical size. It can be an integer between 3
1733 and 13, default value is 5.
1736 Set the chroma effect strength. It can be a float number between -2.0
1737 and 5.0, default value is 0.0.
1742 # Strong luma sharpen effect parameters
1745 # Strong blur of both luma and chroma parameters
1746 unsharp=7:7:-2:7:7:-2
1748 # Use the default values with @command{avconv}
1749 ./avconv -i in.avi -vf "unsharp" out.mp4
1754 Flip the input video vertically.
1757 ./avconv -i in.avi -vf "vflip" out.avi
1762 Deinterlace the input video ("yadif" means "yet another deinterlacing
1765 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
1767 @var{mode} specifies the interlacing mode to adopt, accepts one of the
1772 output 1 frame for each frame
1774 output 1 frame for each field
1776 like 0 but skips spatial interlacing check
1778 like 1 but skips spatial interlacing check
1783 @var{parity} specifies the picture field parity assumed for the input
1784 interlaced video, accepts one of the following values:
1788 assume top field first
1790 assume bottom field first
1792 enable automatic detection
1795 Default value is -1.
1796 If interlacing is unknown or decoder does not export this information,
1797 top field first will be assumed.
1799 @var{auto} specifies if deinterlacer should trust the interlaced flag
1800 and only deinterlace frames marked as interlaced
1804 deinterlace all frames
1806 only deinterlace frames marked as interlaced
1811 @c man end VIDEO FILTERS
1813 @chapter Video Sources
1814 @c man begin VIDEO SOURCES
1816 Below is a description of the currently available video sources.
1820 Buffer video frames, and make them available to the filter chain.
1822 This source is mainly intended for a programmatic use, in particular
1823 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1825 It accepts the following parameters:
1826 @var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1828 All the parameters need to be explicitly defined.
1830 Follows the list of the accepted parameters.
1835 Specify the width and height of the buffered video frames.
1837 @item pix_fmt_string
1838 A string representing the pixel format of the buffered video frames.
1839 It may be a number corresponding to a pixel format, or a pixel format
1842 @item timebase_num, timebase_den
1843 Specify numerator and denomitor of the timebase assumed by the
1844 timestamps of the buffered frames.
1846 @item sample_aspect_ratio.num, sample_aspect_ratio.den
1847 Specify numerator and denominator of the sample aspect ratio assumed
1848 by the video frames.
1853 buffer=320:240:yuv410p:1:24:1:1
1856 will instruct the source to accept video frames with size 320x240 and
1857 with format "yuv410p", assuming 1/24 as the timestamps timebase and
1858 square pixels (1:1 sample aspect ratio).
1859 Since the pixel format with name "yuv410p" corresponds to the number 6
1860 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1861 this example corresponds to:
1863 buffer=320:240:6:1:24
1868 Provide an uniformly colored input.
1870 It accepts the following parameters:
1871 @var{color}:@var{frame_size}:@var{frame_rate}
1873 Follows the description of the accepted parameters.
1878 Specify the color of the source. It can be the name of a color (case
1879 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1880 alpha specifier. The default value is "black".
1883 Specify the size of the sourced video, it may be a string of the form
1884 @var{width}x@var{height}, or the name of a size abbreviation. The
1885 default value is "320x240".
1888 Specify the frame rate of the sourced video, as the number of frames
1889 generated per second. It has to be a string in the format
1890 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1891 number or a valid video frame rate abbreviation. The default value is
1896 For example the following graph description will generate a red source
1897 with an opacity of 0.2, with size "qcif" and a frame rate of 10
1898 frames per second, which will be overlayed over the source connected
1899 to the pad with identifier "in".
1902 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1907 Read a video stream from a movie container.
1909 It accepts the syntax: @var{movie_name}[:@var{options}] where
1910 @var{movie_name} is the name of the resource to read (not necessarily
1911 a file but also a device or a stream accessed through some protocol),
1912 and @var{options} is an optional sequence of @var{key}=@var{value}
1913 pairs, separated by ":".
1915 The description of the accepted options follows.
1919 @item format_name, f
1920 Specifies the format assumed for the movie to read, and can be either
1921 the name of a container or an input device. If not specified the
1922 format is guessed from @var{movie_name} or by probing.
1924 @item seek_point, sp
1925 Specifies the seek point in seconds, the frames will be output
1926 starting from this seek point, the parameter is evaluated with
1927 @code{av_strtod} so the numerical value may be suffixed by an IS
1928 postfix. Default value is "0".
1930 @item stream_index, si
1931 Specifies the index of the video stream to read. If the value is -1,
1932 the best suited video stream will be automatically selected. Default
1937 This filter allows to overlay a second video on top of main input of
1938 a filtergraph as shown in this graph:
1940 input -----------> deltapts0 --> overlay --> output
1943 movie --> scale--> deltapts1 -------+
1946 Some examples follow:
1948 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1949 # on top of the input labelled as "in".
1950 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1951 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1953 # read from a video4linux2 device, and overlay it on top of the input
1955 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1956 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1962 Null video source, never return images. It is mainly useful as a
1963 template and to be employed in analysis / debugging tools.
1965 It accepts as optional parameter a string of the form
1966 @var{width}:@var{height}:@var{timebase}.
1968 @var{width} and @var{height} specify the size of the configured
1969 source. The default values of @var{width} and @var{height} are
1970 respectively 352 and 288 (corresponding to the CIF size format).
1972 @var{timebase} specifies an arithmetic expression representing a
1973 timebase. The expression can contain the constants "PI", "E", "PHI",
1974 "AVTB" (the default timebase), and defaults to the value "AVTB".
1978 Provide a frei0r source.
1980 To enable compilation of this filter you need to install the frei0r
1981 header and configure Libav with --enable-frei0r.
1983 The source supports the syntax:
1985 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1988 @var{size} is the size of the video to generate, may be a string of the
1989 form @var{width}x@var{height} or a frame size abbreviation.
1990 @var{rate} is the rate of the video to generate, may be a string of
1991 the form @var{num}/@var{den} or a frame rate abbreviation.
1992 @var{src_name} is the name to the frei0r source to load. For more
1993 information regarding frei0r and how to set the parameters read the
1994 section @ref{frei0r} in the description of the video filters.
1996 Some examples follow:
1998 # generate a frei0r partik0l source with size 200x200 and framerate 10
1999 # which is overlayed on the overlay filter main input
2000 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
2003 @section rgbtestsrc, testsrc
2005 The @code{rgbtestsrc} source generates an RGB test pattern useful for
2006 detecting RGB vs BGR issues. You should see a red, green and blue
2007 stripe from top to bottom.
2009 The @code{testsrc} source generates a test video pattern, showing a
2010 color pattern, a scrolling gradient and a timestamp. This is mainly
2011 intended for testing purposes.
2013 Both sources accept an optional sequence of @var{key}=@var{value} pairs,
2014 separated by ":". The description of the accepted options follows.
2019 Specify the size of the sourced video, it may be a string of the form
2020 @var{width}x@var{height}, or the name of a size abbreviation. The
2021 default value is "320x240".
2024 Specify the frame rate of the sourced video, as the number of frames
2025 generated per second. It has to be a string in the format
2026 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2027 number or a valid video frame rate abbreviation. The default value is
2031 Set the sample aspect ratio of the sourced video.
2034 Set the video duration of the sourced video. The accepted syntax is:
2036 [-]HH[:MM[:SS[.m...]]]
2039 See also the function @code{av_parse_time()}.
2041 If not specified, or the expressed duration is negative, the video is
2042 supposed to be generated forever.
2045 For example the following:
2047 testsrc=duration=5.3:size=qcif:rate=10
2050 will generate a video with a duration of 5.3 seconds, with size
2051 176x144 and a framerate of 10 frames per second.
2053 @c man end VIDEO SOURCES
2055 @chapter Video Sinks
2056 @c man begin VIDEO SINKS
2058 Below is a description of the currently available video sinks.
2062 Null video sink, do absolutely nothing with the input video. It is
2063 mainly useful as a template and to be employed in analysis / debugging
2066 @c man end VIDEO SINKS