1 @chapter Filtergraph description
2 @c man begin FILTERGRAPH DESCRIPTION
4 A filtergraph is a directed graph of connected filters. It can contain
5 cycles, and there can be multiple links between a pair of
6 filters. Each link has one input pad on one side connecting it to one
7 filter from which it takes its input, and one output pad on the other
8 side connecting it to the one filter accepting its output.
10 Each filter in a filtergraph is an instance of a filter class
11 registered in the application, which defines the features and the
12 number of input and output pads of the filter.
14 A filter with no input pads is called a "source", a filter with no
15 output pads is called a "sink".
17 @anchor{Filtergraph syntax}
18 @section Filtergraph syntax
20 A filtergraph can be represented using a textual representation, which is
21 recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
22 options in @command{avconv} and @option{-vf} in @command{avplay}, and by the
23 @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} function defined in
24 @file{libavfilter/avfiltergraph.h}.
26 A filterchain consists of a sequence of connected filters, each one
27 connected to the previous one in the sequence. A filterchain is
28 represented by a list of ","-separated filter descriptions.
30 A filtergraph consists of a sequence of filterchains. A sequence of
31 filterchains is represented by a list of ";"-separated filterchain
34 A filter is represented by a string of the form:
35 [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
37 @var{filter_name} is the name of the filter class of which the
38 described filter is an instance of, and has to be the name of one of
39 the filter classes registered in the program.
40 The name of the filter class is optionally followed by a string
43 @var{arguments} is a string which contains the parameters used to
44 initialize the filter instance, and are described in the filter
47 The list of arguments can be quoted using the character "'" as initial
48 and ending mark, and the character '\' for escaping the characters
49 within the quoted text; otherwise the argument string is considered
50 terminated when the next special character (belonging to the set
51 "[]=;,") is encountered.
53 The name and arguments of the filter are optionally preceded and
54 followed by a list of link labels.
55 A link label allows to name a link and associate it to a filter output
56 or input pad. The preceding labels @var{in_link_1}
57 ... @var{in_link_N}, are associated to the filter input pads,
58 the following labels @var{out_link_1} ... @var{out_link_M}, are
59 associated to the output pads.
61 When two link labels with the same name are found in the
62 filtergraph, a link between the corresponding input and output pad is
65 If an output pad is not labelled, it is linked by default to the first
66 unlabelled input pad of the next filter in the filterchain.
67 For example in the filterchain:
69 nullsrc, split[L1], [L2]overlay, nullsink
71 the split filter instance has two output pads, and the overlay filter
72 instance two input pads. The first output pad of split is labelled
73 "L1", the first input pad of overlay is labelled "L2", and the second
74 output pad of split is linked to the second input pad of overlay,
75 which are both unlabelled.
77 In a complete filterchain all the unlabelled filter input and output
78 pads must be connected. A filtergraph is considered valid if all the
79 filter input and output pads of all the filterchains are connected.
81 Libavfilter will automatically insert scale filters where format
82 conversion is required. It is possible to specify swscale flags
83 for those automatically inserted scalers by prepending
84 @code{sws_flags=@var{flags};}
85 to the filtergraph description.
87 Follows a BNF description for the filtergraph syntax:
89 @var{NAME} ::= sequence of alphanumeric characters and '_'
90 @var{LINKLABEL} ::= "[" @var{NAME} "]"
91 @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}]
92 @var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
93 @var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
94 @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}]
95 @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
98 @c man end FILTERGRAPH DESCRIPTION
100 @chapter Audio Filters
101 @c man begin AUDIO FILTERS
103 When you configure your Libav build, you can disable any of the
104 existing filters using --disable-filters.
105 The configure output will show the audio filters included in your
108 Below is a description of the currently available audio filters.
112 Convert the input audio to one of the specified formats. The framework will
113 negotiate the most appropriate format to minimize conversions.
115 The filter accepts the following named parameters:
119 A comma-separated list of requested sample formats.
122 A comma-separated list of requested sample rates.
124 @item channel_layouts
125 A comma-separated list of requested channel layouts.
129 If a parameter is omitted, all values are allowed.
131 For example to force the output to either unsigned 8-bit or signed 16-bit stereo:
133 aformat=sample_fmts\=u8\,s16:channel_layouts\=stereo
138 Pass the audio source unchanged to the output.
141 Synchronize audio data with timestamps by squeezing/stretching it and/or
142 dropping samples/adding silence when needed.
144 The filter accepts the following named parameters:
148 Enable stretching/squeezing the data to make it match the timestamps.
151 Minimum difference between timestamps and audio data (in seconds) to trigger
152 adding/dropping samples.
155 Maximum compensation in samples per second.
160 Convert the audio sample format, sample rate and channel layout. This filter is
161 not meant to be used directly, it is inserted automatically by libavfilter
162 whenever conversion is needed. Use the @var{aformat} filter to force a specific
165 @c man end AUDIO FILTERS
167 @chapter Audio Sources
168 @c man begin AUDIO SOURCES
170 Below is a description of the currently available audio sources.
174 Null audio source, never return audio frames. It is mainly useful as a
175 template and to be employed in analysis / debugging tools.
177 It accepts as optional parameter a string of the form
178 @var{sample_rate}:@var{channel_layout}.
180 @var{sample_rate} specify the sample rate, and defaults to 44100.
182 @var{channel_layout} specify the channel layout, and can be either an
183 integer or a string representing a channel layout. The default value
184 of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
186 Check the channel_layout_map definition in
187 @file{libavcodec/audioconvert.c} for the mapping between strings and
188 channel layout values.
190 Follow some examples:
192 # set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
200 Buffer audio frames, and make them available to the filter chain.
202 This source is not intended to be part of user-supplied graph descriptions but
203 for insertion by calling programs through the interface defined in
204 @file{libavfilter/buffersrc.h}.
206 It accepts the following named parameters:
210 Timebase which will be used for timestamps of submitted frames. It must be
211 either a floating-point number or in @var{numerator}/@var{denominator} form.
217 Name of the sample format, as returned by @code{av_get_sample_fmt_name()}.
220 Channel layout of the audio data, in the form that can be accepted by
221 @code{av_get_channel_layout()}.
224 All the parameters need to be explicitly defined.
226 @c man end AUDIO SOURCES
229 @c man begin AUDIO SINKS
231 Below is a description of the currently available audio sinks.
235 Null audio sink, do absolutely nothing with the input audio. It is
236 mainly useful as a template and to be employed in analysis / debugging
240 This sink is intended for programmatic use. Frames that arrive on this sink can
241 be retrieved by the calling program using the interface defined in
242 @file{libavfilter/buffersink.h}.
244 This filter accepts no parameters.
246 @c man end AUDIO SINKS
248 @chapter Video Filters
249 @c man begin VIDEO FILTERS
251 When you configure your Libav build, you can disable any of the
252 existing filters using --disable-filters.
253 The configure output will show the video filters included in your
256 Below is a description of the currently available video filters.
260 Detect frames that are (almost) completely black. Can be useful to
261 detect chapter transitions or commercials. Output lines consist of
262 the frame number of the detected frame, the percentage of blackness,
263 the position in the file if known or -1 and the timestamp in seconds.
265 In order to display the output lines, you need to set the loglevel at
266 least to the AV_LOG_INFO value.
268 The filter accepts the syntax:
270 blackframe[=@var{amount}:[@var{threshold}]]
273 @var{amount} is the percentage of the pixels that have to be below the
274 threshold, and defaults to 98.
276 @var{threshold} is the threshold below which a pixel value is
277 considered black, and defaults to 32.
281 Apply boxblur algorithm to the input video.
283 This filter accepts the parameters:
284 @var{luma_power}:@var{luma_radius}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
286 Chroma and alpha parameters are optional, if not specified they default
287 to the corresponding values set for @var{luma_radius} and
290 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
291 the radius in pixels of the box used for blurring the corresponding
292 input plane. They are expressions, and can contain the following
296 the input width and height in pixels
299 the input chroma image width and height in pixels
302 horizontal and vertical chroma subsample values. For example for the
303 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
306 The radius must be a non-negative number, and must not be greater than
307 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
308 and of @code{min(cw,ch)/2} for the chroma planes.
310 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
311 how many times the boxblur filter is applied to the corresponding
314 Some examples follow:
319 Apply a boxblur filter with luma, chroma, and alpha radius
326 Set luma radius to 2, alpha and chroma radius to 0
332 Set luma and chroma radius to a fraction of the video dimension
334 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
341 Copy the input source unchanged to the output. Mainly useful for
346 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
348 The parameters are expressions containing the following constants:
352 the corresponding mathematical approximated values for e
353 (euler number), pi (greek PI), PHI (golden ratio)
356 the computed values for @var{x} and @var{y}. They are evaluated for
360 the input width and height
363 same as @var{in_w} and @var{in_h}
366 the output (cropped) width and height
369 same as @var{out_w} and @var{out_h}
372 the number of input frame, starting from 0
375 the position in the file of the input frame, NAN if unknown
378 timestamp expressed in seconds, NAN if the input timestamp is unknown
382 The @var{out_w} and @var{out_h} parameters specify the expressions for
383 the width and height of the output (cropped) video. They are
384 evaluated just at the configuration of the filter.
386 The default value of @var{out_w} is "in_w", and the default value of
387 @var{out_h} is "in_h".
389 The expression for @var{out_w} may depend on the value of @var{out_h},
390 and the expression for @var{out_h} may depend on @var{out_w}, but they
391 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
392 evaluated after @var{out_w} and @var{out_h}.
394 The @var{x} and @var{y} parameters specify the expressions for the
395 position of the top-left corner of the output (non-cropped) area. They
396 are evaluated for each frame. If the evaluated value is not valid, it
397 is approximated to the nearest valid value.
399 The default value of @var{x} is "(in_w-out_w)/2", and the default
400 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
401 the center of the input image.
403 The expression for @var{x} may depend on @var{y}, and the expression
404 for @var{y} may depend on @var{x}.
406 Follow some examples:
408 # crop the central input area with size 100x100
411 # crop the central input area with size 2/3 of the input video
412 "crop=2/3*in_w:2/3*in_h"
414 # crop the input video central square
417 # delimit the rectangle with the top-left corner placed at position
418 # 100:100 and the right-bottom corner corresponding to the right-bottom
419 # corner of the input image.
420 crop=in_w-100:in_h-100:100:100
422 # crop 10 pixels from the left and right borders, and 20 pixels from
423 # the top and bottom borders
424 "crop=in_w-2*10:in_h-2*20"
426 # keep only the bottom right quarter of the input image
427 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
429 # crop height for getting Greek harmony
430 "crop=in_w:1/PHI*in_w"
433 "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)"
435 # erratic camera effect depending on timestamp
436 "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)"
438 # set x depending on the value of y
439 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
444 Auto-detect crop size.
446 Calculate necessary cropping parameters and prints the recommended
447 parameters through the logging system. The detected dimensions
448 correspond to the non-black area of the input video.
450 It accepts the syntax:
452 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
458 Threshold, which can be optionally specified from nothing (0) to
459 everything (255), defaults to 24.
462 Value which the width/height should be divisible by, defaults to
463 16. The offset is automatically adjusted to center the video. Use 2 to
464 get only even dimensions (needed for 4:2:2 video). 16 is best when
465 encoding to most video codecs.
468 Counter that determines after how many frames cropdetect will reset
469 the previously detected largest video area and start over to detect
470 the current optimal crop area. Defaults to 0.
472 This can be useful when channel logos distort the video area. 0
473 indicates never reset and return the largest area encountered during
479 Suppress a TV station logo by a simple interpolation of the surrounding
480 pixels. Just set a rectangle covering the logo and watch it disappear
481 (and sometimes something even uglier appear - your mileage may vary).
483 The filter accepts parameters as a string of the form
484 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
485 @var{key}=@var{value} pairs, separated by ":".
487 The description of the accepted parameters follows.
492 Specify the top left corner coordinates of the logo. They must be
496 Specify the width and height of the logo to clear. They must be
500 Specify the thickness of the fuzzy edge of the rectangle (added to
501 @var{w} and @var{h}). The default value is 4.
504 When set to 1, a green rectangle is drawn on the screen to simplify
505 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
506 @var{band} is set to 4. The default value is 0.
510 Some examples follow.
515 Set a rectangle covering the area with top left corner coordinates 0,0
516 and size 100x77, setting a band of size 10:
522 As the previous example, but use named options:
524 delogo=x=0:y=0:w=100:h=77:band=10
531 Draw a colored box on the input image.
533 It accepts the syntax:
535 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
541 Specify the top left corner coordinates of the box. Default to 0.
544 Specify the width and height of the box, if 0 they are interpreted as
545 the input width and height. Default to 0.
548 Specify the color of the box to write, it can be the name of a color
549 (case insensitive match) or a 0xRRGGBB[AA] sequence.
552 Follow some examples:
554 # draw a black box around the edge of the input image
557 # draw a box with color red and an opacity of 50%
558 drawbox=10:20:200:60:red@@0.5"
563 Draw text string or text from specified file on top of video using the
566 To enable compilation of this filter you need to configure Libav with
567 @code{--enable-libfreetype}.
569 The filter also recognizes strftime() sequences in the provided text
570 and expands them accordingly. Check the documentation of strftime().
572 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
575 The description of the accepted parameters follows.
580 The font file to be used for drawing text. Path must be included.
581 This parameter is mandatory.
584 The text string to be drawn. The text must be a sequence of UTF-8
586 This parameter is mandatory if no file is specified with the parameter
590 A text file containing text to be drawn. The text must be a sequence
591 of UTF-8 encoded characters.
593 This parameter is mandatory if no text string is specified with the
594 parameter @var{text}.
596 If both text and textfile are specified, an error is thrown.
599 The offsets where text will be drawn within the video frame.
600 Relative to the top/left border of the output image.
601 They accept expressions similar to the @ref{overlay} filter:
605 the computed values for @var{x} and @var{y}. They are evaluated for
609 main input width and height
612 same as @var{main_w} and @var{main_h}
615 rendered text width and height
618 same as @var{text_w} and @var{text_h}
621 the number of frames processed, starting from 0
624 timestamp expressed in seconds, NAN if the input timestamp is unknown
628 The default value of @var{x} and @var{y} is 0.
631 The font size to be used for drawing text.
632 The default value of @var{fontsize} is 16.
635 The color to be used for drawing fonts.
636 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
637 (e.g. "0xff000033"), possibly followed by an alpha specifier.
638 The default value of @var{fontcolor} is "black".
641 The color to be used for drawing box around text.
642 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
643 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
644 The default value of @var{boxcolor} is "white".
647 Used to draw a box around text using background color.
648 Value should be either 1 (enable) or 0 (disable).
649 The default value of @var{box} is 0.
651 @item shadowx, shadowy
652 The x and y offsets for the text shadow position with respect to the
653 position of the text. They can be either positive or negative
654 values. Default value for both is "0".
657 The color to be used for drawing a shadow behind the drawn text. It
658 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
659 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
660 The default value of @var{shadowcolor} is "black".
663 Flags to be used for loading the fonts.
665 The flags map the corresponding flags supported by libfreetype, and are
666 a combination of the following values:
673 @item vertical_layout
677 @item ignore_global_advance_width
679 @item ignore_transform
686 Default value is "render".
688 For more information consult the documentation for the FT_LOAD_*
692 The size in number of spaces to use for rendering the tab.
696 If true, check and fix text coords to avoid clipping.
699 For example the command:
701 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
704 will draw "Test Text" with font FreeSerif, using the default values
705 for the optional parameters.
709 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
710 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
713 will draw 'Test Text' with font FreeSerif of size 24 at position x=100
714 and y=50 (counting from the top-left corner of the screen), text is
715 yellow with a red box around it. Both the text and the box have an
718 Note that the double quotes are not necessary if spaces are not used
719 within the parameter list.
721 For more information about libfreetype, check:
722 @url{http://www.freetype.org/}.
726 Apply fade-in/out effect to input video.
728 It accepts the parameters:
729 @var{type}:@var{start_frame}:@var{nb_frames}
731 @var{type} specifies if the effect type, can be either "in" for
732 fade-in, or "out" for a fade-out effect.
734 @var{start_frame} specifies the number of the start frame for starting
735 to apply the fade effect.
737 @var{nb_frames} specifies the number of frames for which the fade
738 effect has to last. At the end of the fade-in effect the output video
739 will have the same intensity as the input video, at the end of the
740 fade-out transition the output video will be completely black.
742 A few usage examples follow, usable too as test scenarios.
744 # fade in first 30 frames of video
747 # fade out last 45 frames of a 200-frame video
750 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
751 fade=in:0:25, fade=out:975:25
753 # make first 5 frames black, then fade in from frame 5-24
759 Transform the field order of the input video.
761 It accepts one parameter which specifies the required field order that
762 the input interlaced video will be transformed to. The parameter can
763 assume one of the following values:
767 output bottom field first
769 output top field first
772 Default value is "tff".
774 Transformation is achieved by shifting the picture content up or down
775 by one line, and filling the remaining line with appropriate picture content.
776 This method is consistent with most broadcast field order converters.
778 If the input video is not flagged as being interlaced, or it is already
779 flagged as being of the required output field order then this filter does
780 not alter the incoming video.
782 This filter is very useful when converting to or from PAL DV material,
783 which is bottom field first.
787 ./avconv -i in.vob -vf "fieldorder=bff" out.dv
792 Buffer input images and send them when they are requested.
794 This filter is mainly useful when auto-inserted by the libavfilter
797 The filter does not take parameters.
801 Convert the input video to one of the specified pixel formats.
802 Libavfilter will try to pick one that is supported for the input to
805 The filter accepts a list of pixel format names, separated by ":",
806 for example "yuv420p:monow:rgb24".
808 Some examples follow:
810 # convert the input video to the format "yuv420p"
813 # convert the input video to any of the formats in the list
814 format=yuv420p:yuv444p:yuv410p
819 Convert the video to specified constant framerate by duplicating or dropping
822 This filter accepts the following named parameters:
826 Desired output framerate.
833 Apply a frei0r effect to the input video.
835 To enable compilation of this filter you need to install the frei0r
836 header and configure Libav with --enable-frei0r.
838 The filter supports the syntax:
840 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
843 @var{filter_name} is the name to the frei0r effect to load. If the
844 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
845 is searched in each one of the directories specified by the colon
846 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
847 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
848 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
850 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
851 for the frei0r effect.
853 A frei0r effect parameter can be a boolean (whose values are specified
854 with "y" and "n"), a double, a color (specified by the syntax
855 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
856 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
857 description), a position (specified by the syntax @var{X}/@var{Y},
858 @var{X} and @var{Y} being float numbers) and a string.
860 The number and kind of parameters depend on the loaded effect. If an
861 effect parameter is not specified the default value is set.
863 Some examples follow:
865 # apply the distort0r effect, set the first two double parameters
866 frei0r=distort0r:0.5:0.01
868 # apply the colordistance effect, takes a color as first parameter
869 frei0r=colordistance:0.2/0.3/0.4
870 frei0r=colordistance:violet
871 frei0r=colordistance:0x112233
873 # apply the perspective effect, specify the top left and top right
875 frei0r=perspective:0.2/0.2:0.8/0.2
878 For more information see:
879 @url{http://piksel.org/frei0r}
883 Fix the banding artifacts that are sometimes introduced into nearly flat
884 regions by truncation to 8bit colordepth.
885 Interpolate the gradients that should go where the bands are, and
888 This filter is designed for playback only. Do not use it prior to
889 lossy compression, because compression tends to lose the dither and
890 bring back the bands.
892 The filter takes two optional parameters, separated by ':':
893 @var{strength}:@var{radius}
895 @var{strength} is the maximum amount by which the filter will change
896 any one pixel. Also the threshold for detecting nearly flat
897 regions. Acceptable values range from .51 to 255, default value is
898 1.2, out-of-range values will be clipped to the valid range.
900 @var{radius} is the neighborhood to fit the gradient to. A larger
901 radius makes for smoother gradients, but also prevents the filter from
902 modifying the pixels near detailed regions. Acceptable values are
903 8-32, default value is 16, out-of-range values will be clipped to the
916 Flip the input video horizontally.
918 For example to horizontally flip the input video with @command{avconv}:
920 avconv -i in.avi -vf "hflip" out.avi
925 High precision/quality 3d denoise filter. This filter aims to reduce
926 image noise producing smooth images and making still images really
927 still. It should enhance compressibility.
929 It accepts the following optional parameters:
930 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
934 a non-negative float number which specifies spatial luma strength,
938 a non-negative float number which specifies spatial chroma strength,
939 defaults to 3.0*@var{luma_spatial}/4.0
942 a float number which specifies luma temporal strength, defaults to
943 6.0*@var{luma_spatial}/4.0
946 a float number which specifies chroma temporal strength, defaults to
947 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
950 @section lut, lutrgb, lutyuv
952 Compute a look-up table for binding each pixel component input value
953 to an output value, and apply it to input video.
955 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
956 to an RGB input video.
958 These filters accept in input a ":"-separated list of options, which
959 specify the expressions used for computing the lookup table for the
960 corresponding pixel component values.
962 The @var{lut} filter requires either YUV or RGB pixel formats in
963 input, and accepts the options:
965 @var{c0} (first pixel component)
966 @var{c1} (second pixel component)
967 @var{c2} (third pixel component)
968 @var{c3} (fourth pixel component, corresponds to the alpha component)
971 The exact component associated to each option depends on the format in
974 The @var{lutrgb} filter requires RGB pixel formats in input, and
977 @var{r} (red component)
978 @var{g} (green component)
979 @var{b} (blue component)
980 @var{a} (alpha component)
983 The @var{lutyuv} filter requires YUV pixel formats in input, and
986 @var{y} (Y/luminance component)
987 @var{u} (U/Cb component)
988 @var{v} (V/Cr component)
989 @var{a} (alpha component)
992 The expressions can contain the following constants and functions:
996 the corresponding mathematical approximated values for e
997 (euler number), pi (greek PI), PHI (golden ratio)
1000 the input width and height
1003 input value for the pixel component
1006 the input value clipped in the @var{minval}-@var{maxval} range
1009 maximum value for the pixel component
1012 minimum value for the pixel component
1015 the negated value for the pixel component value clipped in the
1016 @var{minval}-@var{maxval} range , it corresponds to the expression
1017 "maxval-clipval+minval"
1020 the computed value in @var{val} clipped in the
1021 @var{minval}-@var{maxval} range
1023 @item gammaval(gamma)
1024 the computed gamma correction value of the pixel component value
1025 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1027 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1031 All expressions default to "val".
1033 Some examples follow:
1035 # negate input video
1036 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1037 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1039 # the above is the same as
1040 lutrgb="r=negval:g=negval:b=negval"
1041 lutyuv="y=negval:u=negval:v=negval"
1046 # remove chroma components, turns the video into a graytone image
1047 lutyuv="u=128:v=128"
1049 # apply a luma burning effect
1052 # remove green and blue components
1055 # set a constant alpha channel value on input
1056 format=rgba,lutrgb=a="maxval-minval/2"
1058 # correct luminance gamma by a 0.5 factor
1059 lutyuv=y=gammaval(0.5)
1066 This filter accepts an integer in input, if non-zero it negates the
1067 alpha component (if available). The default value in input is 0.
1069 Force libavfilter not to use any of the specified pixel formats for the
1070 input to the next filter.
1072 The filter accepts a list of pixel format names, separated by ":",
1073 for example "yuv420p:monow:rgb24".
1075 Some examples follow:
1077 # force libavfilter to use a format different from "yuv420p" for the
1078 # input to the vflip filter
1079 noformat=yuv420p,vflip
1081 # convert the input video to any of the formats not contained in the list
1082 noformat=yuv420p:yuv444p:yuv410p
1087 Pass the video source unchanged to the output.
1091 Apply video transform using libopencv.
1093 To enable this filter install libopencv library and headers and
1094 configure Libav with --enable-libopencv.
1096 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1098 @var{filter_name} is the name of the libopencv filter to apply.
1100 @var{filter_params} specifies the parameters to pass to the libopencv
1101 filter. If not specified the default values are assumed.
1103 Refer to the official libopencv documentation for more precise
1105 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1107 Follows the list of supported libopencv filters.
1112 Dilate an image by using a specific structuring element.
1113 This filter corresponds to the libopencv function @code{cvDilate}.
1115 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1117 @var{struct_el} represents a structuring element, and has the syntax:
1118 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1120 @var{cols} and @var{rows} represent the number of columns and rows of
1121 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1122 point, and @var{shape} the shape for the structuring element, and
1123 can be one of the values "rect", "cross", "ellipse", "custom".
1125 If the value for @var{shape} is "custom", it must be followed by a
1126 string of the form "=@var{filename}". The file with name
1127 @var{filename} is assumed to represent a binary image, with each
1128 printable character corresponding to a bright pixel. When a custom
1129 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1130 or columns and rows of the read file are assumed instead.
1132 The default value for @var{struct_el} is "3x3+0x0/rect".
1134 @var{nb_iterations} specifies the number of times the transform is
1135 applied to the image, and defaults to 1.
1137 Follow some example:
1139 # use the default values
1142 # dilate using a structuring element with a 5x5 cross, iterate two times
1143 ocv=dilate=5x5+2x2/cross:2
1145 # read the shape from the file diamond.shape, iterate two times
1146 # the file diamond.shape may contain a pattern of characters like this:
1152 # the specified cols and rows are ignored (but not the anchor point coordinates)
1153 ocv=0x0+2x2/custom=diamond.shape:2
1158 Erode an image by using a specific structuring element.
1159 This filter corresponds to the libopencv function @code{cvErode}.
1161 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1162 with the same syntax and semantics as the @ref{dilate} filter.
1166 Smooth the input video.
1168 The filter takes the following parameters:
1169 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1171 @var{type} is the type of smooth filter to apply, and can be one of
1172 the following values: "blur", "blur_no_scale", "median", "gaussian",
1173 "bilateral". The default value is "gaussian".
1175 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1176 parameters whose meanings depend on smooth type. @var{param1} and
1177 @var{param2} accept integer positive values or 0, @var{param3} and
1178 @var{param4} accept float values.
1180 The default value for @var{param1} is 3, the default value for the
1181 other parameters is 0.
1183 These parameters correspond to the parameters assigned to the
1184 libopencv function @code{cvSmooth}.
1189 Overlay one video on top of another.
1191 It takes two inputs and one output, the first input is the "main"
1192 video on which the second input is overlayed.
1194 It accepts the parameters: @var{x}:@var{y}.
1196 @var{x} is the x coordinate of the overlayed video on the main video,
1197 @var{y} is the y coordinate. The parameters are expressions containing
1198 the following parameters:
1201 @item main_w, main_h
1202 main input width and height
1205 same as @var{main_w} and @var{main_h}
1207 @item overlay_w, overlay_h
1208 overlay input width and height
1211 same as @var{overlay_w} and @var{overlay_h}
1214 Be aware that frames are taken from each input video in timestamp
1215 order, hence, if their initial timestamps differ, it is a a good idea
1216 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1217 have them begin in the same zero timestamp, as it does the example for
1218 the @var{movie} filter.
1220 Follow some examples:
1222 # draw the overlay at 10 pixels from the bottom right
1223 # corner of the main video.
1224 overlay=main_w-overlay_w-10:main_h-overlay_h-10
1226 # insert a transparent PNG logo in the bottom left corner of the input
1227 avconv -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
1229 # insert 2 different transparent PNG logos (second logo on bottom
1231 avconv -i input -i logo1 -i logo2 -filter_complex
1232 'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
1234 # add a transparent color layer on top of the main video,
1235 # WxH specifies the size of the main input to the overlay filter
1236 color=red@.3:WxH [over]; [in][over] overlay [out]
1239 You can chain together more overlays but the efficiency of such
1240 approach is yet to be tested.
1244 Add paddings to the input image, and places the original input at the
1245 given coordinates @var{x}, @var{y}.
1247 It accepts the following parameters:
1248 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1250 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1251 expressions containing the following constants:
1255 the corresponding mathematical approximated values for e
1256 (euler number), pi (greek PI), phi (golden ratio)
1259 the input video width and height
1262 same as @var{in_w} and @var{in_h}
1265 the output width and height, that is the size of the padded area as
1266 specified by the @var{width} and @var{height} expressions
1269 same as @var{out_w} and @var{out_h}
1272 x and y offsets as specified by the @var{x} and @var{y}
1273 expressions, or NAN if not yet specified
1276 input display aspect ratio, same as @var{iw} / @var{ih}
1279 horizontal and vertical chroma subsample values. For example for the
1280 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1283 Follows the description of the accepted parameters.
1288 Specify the size of the output image with the paddings added. If the
1289 value for @var{width} or @var{height} is 0, the corresponding input size
1290 is used for the output.
1292 The @var{width} expression can reference the value set by the
1293 @var{height} expression, and vice versa.
1295 The default value of @var{width} and @var{height} is 0.
1299 Specify the offsets where to place the input image in the padded area
1300 with respect to the top/left border of the output image.
1302 The @var{x} expression can reference the value set by the @var{y}
1303 expression, and vice versa.
1305 The default value of @var{x} and @var{y} is 0.
1309 Specify the color of the padded area, it can be the name of a color
1310 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1312 The default value of @var{color} is "black".
1316 Some examples follow:
1319 # Add paddings with color "violet" to the input video. Output video
1320 # size is 640x480, the top-left corner of the input video is placed at
1322 pad=640:480:0:40:violet
1324 # pad the input to get an output with dimensions increased bt 3/2,
1325 # and put the input video at the center of the padded area
1326 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1328 # pad the input to get a squared output with size equal to the maximum
1329 # value between the input width and height, and put the input video at
1330 # the center of the padded area
1331 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1333 # pad the input to get a final w/h ratio of 16:9
1334 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1336 # double output size and put the input video in the bottom-right
1337 # corner of the output padded area
1338 pad="2*iw:2*ih:ow-iw:oh-ih"
1341 @section pixdesctest
1343 Pixel format descriptor test filter, mainly useful for internal
1344 testing. The output video should be equal to the input video.
1348 format=monow, pixdesctest
1351 can be used to test the monowhite pixel format descriptor definition.
1355 Scale the input video to @var{width}:@var{height} and/or convert the image format.
1357 The parameters @var{width} and @var{height} are expressions containing
1358 the following constants:
1362 the corresponding mathematical approximated values for e
1363 (euler number), pi (greek PI), phi (golden ratio)
1366 the input width and height
1369 same as @var{in_w} and @var{in_h}
1372 the output (cropped) width and height
1375 same as @var{out_w} and @var{out_h}
1378 input display aspect ratio, same as @var{iw} / @var{ih}
1381 input sample aspect ratio
1384 horizontal and vertical chroma subsample values. For example for the
1385 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1388 If the input image format is different from the format requested by
1389 the next filter, the scale filter will convert the input to the
1392 If the value for @var{width} or @var{height} is 0, the respective input
1393 size is used for the output.
1395 If the value for @var{width} or @var{height} is -1, the scale filter will
1396 use, for the respective output size, a value that maintains the aspect
1397 ratio of the input image.
1399 The default value of @var{width} and @var{height} is 0.
1401 Some examples follow:
1403 # scale the input video to a size of 200x100.
1406 # scale the input to 2x
1408 # the above is the same as
1411 # scale the input to half size
1414 # increase the width, and set the height to the same size
1417 # seek for Greek harmony
1421 # increase the height, and set the width to 3/2 of the height
1424 # increase the size, but make the size a multiple of the chroma
1425 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1427 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1428 scale='min(500\, iw*3/2):-1'
1432 Select frames to pass in output.
1434 It accepts in input an expression, which is evaluated for each input
1435 frame. If the expression is evaluated to a non-zero value, the frame
1436 is selected and passed to the output, otherwise it is discarded.
1438 The expression can contain the following constants:
1451 the sequential number of the filtered frame, starting from 0
1454 the sequential number of the selected frame, starting from 0
1456 @item prev_selected_n
1457 the sequential number of the last selected frame, NAN if undefined
1460 timebase of the input timestamps
1463 the PTS (Presentation TimeStamp) of the filtered video frame,
1464 expressed in @var{TB} units, NAN if undefined
1467 the PTS (Presentation TimeStamp) of the filtered video frame,
1468 expressed in seconds, NAN if undefined
1471 the PTS of the previously filtered video frame, NAN if undefined
1473 @item prev_selected_pts
1474 the PTS of the last previously filtered video frame, NAN if undefined
1476 @item prev_selected_t
1477 the PTS of the last previously selected video frame, NAN if undefined
1480 the PTS of the first video frame in the video, NAN if undefined
1483 the time of the first video frame in the video, NAN if undefined
1486 the type of the filtered frame, can assume one of the following
1498 @item interlace_type
1499 the frame interlace type, can assume one of the following values:
1502 the frame is progressive (not interlaced)
1504 the frame is top-field-first
1506 the frame is bottom-field-first
1510 1 if the filtered frame is a key-frame, 0 otherwise
1513 the position in the file of the filtered frame, -1 if the information
1514 is not available (e.g. for synthetic video)
1517 The default value of the select expression is "1".
1519 Some examples follow:
1522 # select all frames in input
1525 # the above is the same as:
1531 # select only I-frames
1532 select='eq(pict_type\,I)'
1534 # select one frame every 100
1535 select='not(mod(n\,100))'
1537 # select only frames contained in the 10-20 time interval
1538 select='gte(t\,10)*lte(t\,20)'
1540 # select only I frames contained in the 10-20 time interval
1541 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
1543 # select frames with a minimum distance of 10 seconds
1544 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
1550 Set the Display Aspect Ratio for the filter output video.
1552 This is done by changing the specified Sample (aka Pixel) Aspect
1553 Ratio, according to the following equation:
1554 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1556 Keep in mind that this filter does not modify the pixel dimensions of
1557 the video frame. Also the display aspect ratio set by this filter may
1558 be changed by later filters in the filterchain, e.g. in case of
1559 scaling or if another "setdar" or a "setsar" filter is applied.
1561 The filter accepts a parameter string which represents the wanted
1562 display aspect ratio.
1563 The parameter can be a floating point number string, or an expression
1564 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1565 numerator and denominator of the aspect ratio.
1566 If the parameter is not specified, it is assumed the value "0:1".
1568 For example to change the display aspect ratio to 16:9, specify:
1571 # the above is equivalent to
1575 See also the @ref{setsar} filter documentation.
1579 Change the PTS (presentation timestamp) of the input video frames.
1581 Accept in input an expression evaluated through the eval API, which
1582 can contain the following constants:
1586 the presentation timestamp in input
1598 the count of the input frame, starting from 0.
1601 the PTS of the first video frame
1604 tell if the current frame is interlaced
1607 original position in the file of the frame, or undefined if undefined
1608 for the current frame
1618 Some examples follow:
1621 # start counting PTS from zero
1633 # fixed rate 25 fps with some jitter
1634 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1640 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1642 Note that as a consequence of the application of this filter, the
1643 output display aspect ratio will change according to the following
1645 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1647 Keep in mind that the sample aspect ratio set by this filter may be
1648 changed by later filters in the filterchain, e.g. if another "setsar"
1649 or a "setdar" filter is applied.
1651 The filter accepts a parameter string which represents the wanted
1652 sample aspect ratio.
1653 The parameter can be a floating point number string, or an expression
1654 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1655 numerator and denominator of the aspect ratio.
1656 If the parameter is not specified, it is assumed the value "0:1".
1658 For example to change the sample aspect ratio to 10:11, specify:
1665 Set the timebase to use for the output frames timestamps.
1666 It is mainly useful for testing timebase configuration.
1668 It accepts in input an arithmetic expression representing a rational.
1669 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1670 default timebase), and "intb" (the input timebase).
1672 The default value for the input is "intb".
1674 Follow some examples.
1677 # set the timebase to 1/25
1680 # set the timebase to 1/10
1683 #set the timebase to 1001/1000
1686 #set the timebase to 2*intb
1689 #set the default timebase value
1695 Show a line containing various information for each input video frame.
1696 The input video is not modified.
1698 The shown line contains a sequence of key/value pairs of the form
1699 @var{key}:@var{value}.
1701 A description of each shown parameter follows:
1705 sequential number of the input frame, starting from 0
1708 Presentation TimeStamp of the input frame, expressed as a number of
1709 time base units. The time base unit depends on the filter input pad.
1712 Presentation TimeStamp of the input frame, expressed as a number of
1716 position of the frame in the input stream, -1 if this information in
1717 unavailable and/or meaningless (for example in case of synthetic video)
1723 sample aspect ratio of the input frame, expressed in the form
1727 size of the input frame, expressed in the form
1728 @var{width}x@var{height}
1731 interlaced mode ("P" for "progressive", "T" for top field first, "B"
1732 for bottom field first)
1735 1 if the frame is a key frame, 0 otherwise
1738 picture type of the input frame ("I" for an I-frame, "P" for a
1739 P-frame, "B" for a B-frame, "?" for unknown type).
1740 Check also the documentation of the @code{AVPictureType} enum and of
1741 the @code{av_get_picture_type_char} function defined in
1742 @file{libavutil/avutil.h}.
1745 Adler-32 checksum of all the planes of the input frame
1747 @item plane_checksum
1748 Adler-32 checksum of each plane of the input frame, expressed in the form
1749 "[@var{c0} @var{c1} @var{c2} @var{c3}]"
1754 Pass the images of input video on to next video filter as multiple
1758 ./avconv -i in.avi -vf "slicify=32" out.avi
1761 The filter accepts the slice height as parameter. If the parameter is
1762 not specified it will use the default value of 16.
1764 Adding this in the beginning of filter chains should make filtering
1765 faster due to better use of the memory cache.
1769 Split input video into several identical outputs.
1771 The filter accepts a single parameter which specifies the number of outputs. If
1772 unspecified, it defaults to 2.
1776 avconv -i INPUT -filter_complex split=5 OUTPUT
1778 will create 5 copies of the input video.
1782 Transpose rows with columns in the input video and optionally flip it.
1784 It accepts a parameter representing an integer, which can assume the
1789 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1797 Rotate by 90 degrees clockwise, that is:
1805 Rotate by 90 degrees counterclockwise, that is:
1813 Rotate by 90 degrees clockwise and vertically flip, that is:
1823 Sharpen or blur the input video.
1825 It accepts the following parameters:
1826 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1828 Negative values for the amount will blur the input video, while positive
1829 values will sharpen. All parameters are optional and default to the
1830 equivalent of the string '5:5:1.0:5:5:0.0'.
1835 Set the luma matrix horizontal size. It can be an integer between 3
1836 and 13, default value is 5.
1839 Set the luma matrix vertical size. It can be an integer between 3
1840 and 13, default value is 5.
1843 Set the luma effect strength. It can be a float number between -2.0
1844 and 5.0, default value is 1.0.
1846 @item chroma_msize_x
1847 Set the chroma matrix horizontal size. It can be an integer between 3
1848 and 13, default value is 5.
1850 @item chroma_msize_y
1851 Set the chroma matrix vertical size. It can be an integer between 3
1852 and 13, default value is 5.
1855 Set the chroma effect strength. It can be a float number between -2.0
1856 and 5.0, default value is 0.0.
1861 # Strong luma sharpen effect parameters
1864 # Strong blur of both luma and chroma parameters
1865 unsharp=7:7:-2:7:7:-2
1867 # Use the default values with @command{avconv}
1868 ./avconv -i in.avi -vf "unsharp" out.mp4
1873 Flip the input video vertically.
1876 ./avconv -i in.avi -vf "vflip" out.avi
1881 Deinterlace the input video ("yadif" means "yet another deinterlacing
1884 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
1886 @var{mode} specifies the interlacing mode to adopt, accepts one of the
1891 output 1 frame for each frame
1893 output 1 frame for each field
1895 like 0 but skips spatial interlacing check
1897 like 1 but skips spatial interlacing check
1902 @var{parity} specifies the picture field parity assumed for the input
1903 interlaced video, accepts one of the following values:
1907 assume top field first
1909 assume bottom field first
1911 enable automatic detection
1914 Default value is -1.
1915 If interlacing is unknown or decoder does not export this information,
1916 top field first will be assumed.
1918 @var{auto} specifies if deinterlacer should trust the interlaced flag
1919 and only deinterlace frames marked as interlaced
1923 deinterlace all frames
1925 only deinterlace frames marked as interlaced
1930 @c man end VIDEO FILTERS
1932 @chapter Video Sources
1933 @c man begin VIDEO SOURCES
1935 Below is a description of the currently available video sources.
1939 Buffer video frames, and make them available to the filter chain.
1941 This source is mainly intended for a programmatic use, in particular
1942 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1944 It accepts the following parameters:
1945 @var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1947 All the parameters need to be explicitly defined.
1949 Follows the list of the accepted parameters.
1954 Specify the width and height of the buffered video frames.
1956 @item pix_fmt_string
1957 A string representing the pixel format of the buffered video frames.
1958 It may be a number corresponding to a pixel format, or a pixel format
1961 @item timebase_num, timebase_den
1962 Specify numerator and denomitor of the timebase assumed by the
1963 timestamps of the buffered frames.
1965 @item sample_aspect_ratio.num, sample_aspect_ratio.den
1966 Specify numerator and denominator of the sample aspect ratio assumed
1967 by the video frames.
1972 buffer=320:240:yuv410p:1:24:1:1
1975 will instruct the source to accept video frames with size 320x240 and
1976 with format "yuv410p", assuming 1/24 as the timestamps timebase and
1977 square pixels (1:1 sample aspect ratio).
1978 Since the pixel format with name "yuv410p" corresponds to the number 6
1979 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1980 this example corresponds to:
1982 buffer=320:240:6:1:24
1987 Provide an uniformly colored input.
1989 It accepts the following parameters:
1990 @var{color}:@var{frame_size}:@var{frame_rate}
1992 Follows the description of the accepted parameters.
1997 Specify the color of the source. It can be the name of a color (case
1998 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1999 alpha specifier. The default value is "black".
2002 Specify the size of the sourced video, it may be a string of the form
2003 @var{width}x@var{height}, or the name of a size abbreviation. The
2004 default value is "320x240".
2007 Specify the frame rate of the sourced video, as the number of frames
2008 generated per second. It has to be a string in the format
2009 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2010 number or a valid video frame rate abbreviation. The default value is
2015 For example the following graph description will generate a red source
2016 with an opacity of 0.2, with size "qcif" and a frame rate of 10
2017 frames per second, which will be overlayed over the source connected
2018 to the pad with identifier "in".
2021 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2026 Read a video stream from a movie container.
2028 It accepts the syntax: @var{movie_name}[:@var{options}] where
2029 @var{movie_name} is the name of the resource to read (not necessarily
2030 a file but also a device or a stream accessed through some protocol),
2031 and @var{options} is an optional sequence of @var{key}=@var{value}
2032 pairs, separated by ":".
2034 The description of the accepted options follows.
2038 @item format_name, f
2039 Specifies the format assumed for the movie to read, and can be either
2040 the name of a container or an input device. If not specified the
2041 format is guessed from @var{movie_name} or by probing.
2043 @item seek_point, sp
2044 Specifies the seek point in seconds, the frames will be output
2045 starting from this seek point, the parameter is evaluated with
2046 @code{av_strtod} so the numerical value may be suffixed by an IS
2047 postfix. Default value is "0".
2049 @item stream_index, si
2050 Specifies the index of the video stream to read. If the value is -1,
2051 the best suited video stream will be automatically selected. Default
2056 This filter allows to overlay a second video on top of main input of
2057 a filtergraph as shown in this graph:
2059 input -----------> deltapts0 --> overlay --> output
2062 movie --> scale--> deltapts1 -------+
2065 Some examples follow:
2067 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
2068 # on top of the input labelled as "in".
2069 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2070 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2072 # read from a video4linux2 device, and overlay it on top of the input
2074 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2075 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2081 Null video source, never return images. It is mainly useful as a
2082 template and to be employed in analysis / debugging tools.
2084 It accepts as optional parameter a string of the form
2085 @var{width}:@var{height}:@var{timebase}.
2087 @var{width} and @var{height} specify the size of the configured
2088 source. The default values of @var{width} and @var{height} are
2089 respectively 352 and 288 (corresponding to the CIF size format).
2091 @var{timebase} specifies an arithmetic expression representing a
2092 timebase. The expression can contain the constants "PI", "E", "PHI",
2093 "AVTB" (the default timebase), and defaults to the value "AVTB".
2097 Provide a frei0r source.
2099 To enable compilation of this filter you need to install the frei0r
2100 header and configure Libav with --enable-frei0r.
2102 The source supports the syntax:
2104 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
2107 @var{size} is the size of the video to generate, may be a string of the
2108 form @var{width}x@var{height} or a frame size abbreviation.
2109 @var{rate} is the rate of the video to generate, may be a string of
2110 the form @var{num}/@var{den} or a frame rate abbreviation.
2111 @var{src_name} is the name to the frei0r source to load. For more
2112 information regarding frei0r and how to set the parameters read the
2113 section @ref{frei0r} in the description of the video filters.
2115 Some examples follow:
2117 # generate a frei0r partik0l source with size 200x200 and framerate 10
2118 # which is overlayed on the overlay filter main input
2119 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
2122 @section rgbtestsrc, testsrc
2124 The @code{rgbtestsrc} source generates an RGB test pattern useful for
2125 detecting RGB vs BGR issues. You should see a red, green and blue
2126 stripe from top to bottom.
2128 The @code{testsrc} source generates a test video pattern, showing a
2129 color pattern, a scrolling gradient and a timestamp. This is mainly
2130 intended for testing purposes.
2132 Both sources accept an optional sequence of @var{key}=@var{value} pairs,
2133 separated by ":". The description of the accepted options follows.
2138 Specify the size of the sourced video, it may be a string of the form
2139 @var{width}x@var{height}, or the name of a size abbreviation. The
2140 default value is "320x240".
2143 Specify the frame rate of the sourced video, as the number of frames
2144 generated per second. It has to be a string in the format
2145 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2146 number or a valid video frame rate abbreviation. The default value is
2150 Set the sample aspect ratio of the sourced video.
2153 Set the video duration of the sourced video. The accepted syntax is:
2155 [-]HH[:MM[:SS[.m...]]]
2158 See also the function @code{av_parse_time()}.
2160 If not specified, or the expressed duration is negative, the video is
2161 supposed to be generated forever.
2164 For example the following:
2166 testsrc=duration=5.3:size=qcif:rate=10
2169 will generate a video with a duration of 5.3 seconds, with size
2170 176x144 and a framerate of 10 frames per second.
2172 @c man end VIDEO SOURCES
2174 @chapter Video Sinks
2175 @c man begin VIDEO SINKS
2177 Below is a description of the currently available video sinks.
2181 Buffer video frames, and make them available to the end of the filter
2184 This sink is intended for a programmatic use through the interface defined in
2185 @file{libavfilter/buffersink.h}.
2189 Null video sink, do absolutely nothing with the input video. It is
2190 mainly useful as a template and to be employed in analysis / debugging
2193 @c man end VIDEO SINKS