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 of the ff*
21 tools, and by the @code{avfilter_graph_parse()} function defined in
22 @file{libavfilter/avfiltergraph.h}.
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 FFmpeg 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 Convert the input audio format to the specified formats.
106 The filter accepts a string of the form:
107 "@var{sample_format}:@var{channel_layout}:@var{packing_format}".
109 @var{sample_format} specifies the sample format, and can be a string or
110 the corresponding numeric value defined in @file{libavutil/samplefmt.h}.
112 @var{channel_layout} specifies the channel layout, and can be a string
113 or the corresponding number value defined in @file{libavutil/chlayout.h}.
115 @var{packing_format} specifies the type of packing in output, can be one
116 of "planar" or "packed", or the corresponding numeric values "0" or "1".
118 The special parameter "auto", signifies that the filter will
119 automatically select the output format depending on the output filter.
121 Some examples follow.
125 Convert input to unsigned 8-bit, stereo, packed:
127 aconvert=u8:stereo:packed
131 Convert input to unsigned 8-bit, automatically select out channel layout
134 aconvert=u8:auto:auto
140 Convert the input audio to one of the specified formats. The framework will
141 negotiate the most appropriate format to minimize conversions.
143 The filter accepts three lists of formats, separated by ":", in the form:
144 "@var{sample_formats}:@var{channel_layouts}:@var{packing_formats}".
146 Elements in each list are separated by "," which has to be escaped in the
147 filtergraph specification.
149 The special parameter "all", in place of a list of elements, signifies all
152 Some examples follow:
154 aformat=u8\\,s16:mono:packed
156 aformat=s16:mono\\,stereo:all
161 Pass the audio source unchanged to the output.
165 Resample the input audio to the specified sample rate.
167 The filter accepts exactly one parameter, the output sample rate. If not
168 specified then the filter will automatically convert between its input
169 and output sample rates.
171 For example, to resample the input audio to 44100Hz:
178 Show a line containing various information for each input audio frame.
179 The input audio is not modified.
181 The shown line contains a sequence of key/value pairs of the form
182 @var{key}:@var{value}.
184 A description of each shown parameter follows:
188 sequential number of the input frame, starting from 0
191 presentation TimeStamp of the input frame, expressed as a number of
192 time base units. The time base unit depends on the filter input pad, and
193 is usually 1/@var{sample_rate}.
196 presentation TimeStamp of the input frame, expressed as a number of
200 position of the frame in the input stream, -1 if this information in
201 unavailable and/or meanigless (for example in case of synthetic audio)
207 channel layout description
210 number of samples (per each channel) contained in the filtered frame
213 sample rate for the audio frame
216 if the packing format is planar, 0 if packed
219 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
222 Adler-32 checksum (printed in hexadecimal) for each input frame plane,
223 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3} @var{c4} @var{c5}
227 @c man end AUDIO FILTERS
229 @chapter Audio Sources
230 @c man begin AUDIO SOURCES
232 Below is a description of the currently available audio sources.
236 Buffer audio frames, and make them available to the filter chain.
238 This source is mainly intended for a programmatic use, in particular
239 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
241 It accepts the following mandatory parameters:
242 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}:@var{packing}
247 The sample rate of the incoming audio buffers.
250 The sample format of the incoming audio buffers.
251 Either a sample format name or its corresponging integer representation from
252 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
255 The channel layout of the incoming audio buffers.
256 Either a channel layout name from channel_layout_map in
257 @file{libavutil/audioconvert.c} or its corresponding integer representation
258 from the AV_CH_LAYOUT_* macros in @file{libavutil/audioconvert.h}
261 Either "packed" or "planar", or their integer representation: 0 or 1
268 abuffer=44100:s16:stereo:planar
271 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
272 Since the sample format with name "s16" corresponds to the number
273 1 and the "stereo" channel layout corresponds to the value 3, this is
281 Generate an audio signal specified by an expression.
283 This source accepts in input one or more expressions (one for each
284 channel), which are evaluated and used to generate a corresponding
287 It accepts the syntax: @var{exprs}[::@var{options}].
288 @var{exprs} is a list of expressions separated by ":", one for each
289 separate channel. The output channel layout depends on the number of
290 provided expressions, up to 8 channels are supported.
292 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
295 The description of the accepted options follows.
300 Set the number of samples per channel per each output frame,
304 Specify the sample rate, default to 44100.
307 Each expression in @var{exprs} can contain the following constants:
311 number of the evaluated sample, starting from 0
314 time of the evaluated sample expressed in seconds, starting from 0
333 Generate a sin signal with frequence of 440 Hz, set sample rate to
336 aevalsrc="sin(440*2*PI*t)::s=8000"
340 Generate white noise:
342 aevalsrc="-2+random(0)"
346 Generate an amplitude modulated signal:
348 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
352 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
354 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
361 Read an audio stream from a movie container.
363 It accepts the syntax: @var{movie_name}[:@var{options}] where
364 @var{movie_name} is the name of the resource to read (not necessarily
365 a file but also a device or a stream accessed through some protocol),
366 and @var{options} is an optional sequence of @var{key}=@var{value}
367 pairs, separated by ":".
369 The description of the accepted options follows.
374 Specify the format assumed for the movie to read, and can be either
375 the name of a container or an input device. If not specified the
376 format is guessed from @var{movie_name} or by probing.
379 Specify the seek point in seconds, the frames will be output
380 starting from this seek point, the parameter is evaluated with
381 @code{av_strtod} so the numerical value may be suffixed by an IS
382 postfix. Default value is "0".
384 @item stream_index, si
385 Specify the index of the audio stream to read. If the value is -1,
386 the best suited audio stream will be automatically selected. Default
393 Null audio source, return unprocessed audio frames. It is mainly useful
394 as a template and to be employed in analysis / debugging tools, or as
395 the source for filters which ignore the input data (for example the sox
398 It accepts an optional sequence of @var{key}=@var{value} pairs,
401 The description of the accepted options follows.
406 Specify the sample rate, and defaults to 44100.
408 @item channel_layout, cl
410 Specify the channel layout, and can be either an integer or a string
411 representing a channel layout. The default value of @var{channel_layout}
414 Check the channel_layout_map definition in
415 @file{libavcodec/audioconvert.c} for the mapping between strings and
416 channel layout values.
419 Set the number of samples per requested frames.
423 Follow some examples:
425 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
426 anullsrc=r=48000:cl=4
429 anullsrc=r=48000:cl=mono
432 @c man end AUDIO SOURCES
435 @c man begin AUDIO SINKS
437 Below is a description of the currently available audio sinks.
441 Buffer audio frames, and make them available to the end of filter chain.
443 This sink is mainly intended for programmatic use, in particular
444 through the interface defined in @file{libavfilter/buffersink.h}.
446 It requires a pointer to an AVABufferSinkContext structure, which
447 defines the incoming buffers' formats, to be passed as the opaque
448 parameter to @code{avfilter_init_filter} for initialization.
452 Null audio sink, do absolutely nothing with the input audio. It is
453 mainly useful as a template and to be employed in analysis / debugging
456 @c man end AUDIO SINKS
458 @chapter Video Filters
459 @c man begin VIDEO FILTERS
461 When you configure your FFmpeg build, you can disable any of the
462 existing filters using --disable-filters.
463 The configure output will show the video filters included in your
466 Below is a description of the currently available video filters.
470 Detect frames that are (almost) completely black. Can be useful to
471 detect chapter transitions or commercials. Output lines consist of
472 the frame number of the detected frame, the percentage of blackness,
473 the position in the file if known or -1 and the timestamp in seconds.
475 In order to display the output lines, you need to set the loglevel at
476 least to the AV_LOG_INFO value.
478 The filter accepts the syntax:
480 blackframe[=@var{amount}:[@var{threshold}]]
483 @var{amount} is the percentage of the pixels that have to be below the
484 threshold, and defaults to 98.
486 @var{threshold} is the threshold below which a pixel value is
487 considered black, and defaults to 32.
491 Apply boxblur algorithm to the input video.
493 This filter accepts the parameters:
494 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
496 Chroma and alpha parameters are optional, if not specified they default
497 to the corresponding values set for @var{luma_radius} and
500 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
501 the radius in pixels of the box used for blurring the corresponding
502 input plane. They are expressions, and can contain the following
506 the input width and heigth in pixels
509 the input chroma image width and height in pixels
512 horizontal and vertical chroma subsample values. For example for the
513 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
516 The radius must be a non-negative number, and must not be greater than
517 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
518 and of @code{min(cw,ch)/2} for the chroma planes.
520 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
521 how many times the boxblur filter is applied to the corresponding
524 Some examples follow:
529 Apply a boxblur filter with luma, chroma, and alpha radius
536 Set luma radius to 2, alpha and chroma radius to 0
542 Set luma and chroma radius to a fraction of the video dimension
544 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
551 Copy the input source unchanged to the output. Mainly useful for
556 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
558 The parameters are expressions containing the following constants:
562 the computed values for @var{x} and @var{y}. They are evaluated for
566 the input width and height
569 same as @var{in_w} and @var{in_h}
572 the output (cropped) width and height
575 same as @var{out_w} and @var{out_h}
578 same as @var{iw} / @var{ih}
581 input sample aspect ratio
584 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
587 horizontal and vertical chroma subsample values. For example for the
588 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
591 the number of input frame, starting from 0
594 the position in the file of the input frame, NAN if unknown
597 timestamp expressed in seconds, NAN if the input timestamp is unknown
601 The @var{out_w} and @var{out_h} parameters specify the expressions for
602 the width and height of the output (cropped) video. They are
603 evaluated just at the configuration of the filter.
605 The default value of @var{out_w} is "in_w", and the default value of
606 @var{out_h} is "in_h".
608 The expression for @var{out_w} may depend on the value of @var{out_h},
609 and the expression for @var{out_h} may depend on @var{out_w}, but they
610 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
611 evaluated after @var{out_w} and @var{out_h}.
613 The @var{x} and @var{y} parameters specify the expressions for the
614 position of the top-left corner of the output (non-cropped) area. They
615 are evaluated for each frame. If the evaluated value is not valid, it
616 is approximated to the nearest valid value.
618 The default value of @var{x} is "(in_w-out_w)/2", and the default
619 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
620 the center of the input image.
622 The expression for @var{x} may depend on @var{y}, and the expression
623 for @var{y} may depend on @var{x}.
625 Follow some examples:
627 # crop the central input area with size 100x100
630 # crop the central input area with size 2/3 of the input video
631 "crop=2/3*in_w:2/3*in_h"
633 # crop the input video central square
636 # delimit the rectangle with the top-left corner placed at position
637 # 100:100 and the right-bottom corner corresponding to the right-bottom
638 # corner of the input image.
639 crop=in_w-100:in_h-100:100:100
641 # crop 10 pixels from the left and right borders, and 20 pixels from
642 # the top and bottom borders
643 "crop=in_w-2*10:in_h-2*20"
645 # keep only the bottom right quarter of the input image
646 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
648 # crop height for getting Greek harmony
649 "crop=in_w:1/PHI*in_w"
652 "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)"
654 # erratic camera effect depending on timestamp
655 "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)"
657 # set x depending on the value of y
658 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
663 Auto-detect crop size.
665 Calculate necessary cropping parameters and prints the recommended
666 parameters through the logging system. The detected dimensions
667 correspond to the non-black area of the input video.
669 It accepts the syntax:
671 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
677 Threshold, which can be optionally specified from nothing (0) to
678 everything (255), defaults to 24.
681 Value which the width/height should be divisible by, defaults to
682 16. The offset is automatically adjusted to center the video. Use 2 to
683 get only even dimensions (needed for 4:2:2 video). 16 is best when
684 encoding to most video codecs.
687 Counter that determines after how many frames cropdetect will reset
688 the previously detected largest video area and start over to detect
689 the current optimal crop area. Defaults to 0.
691 This can be useful when channel logos distort the video area. 0
692 indicates never reset and return the largest area encountered during
698 Suppress a TV station logo by a simple interpolation of the surrounding
699 pixels. Just set a rectangle covering the logo and watch it disappear
700 (and sometimes something even uglier appear - your mileage may vary).
702 The filter accepts parameters as a string of the form
703 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
704 @var{key}=@var{value} pairs, separated by ":".
706 The description of the accepted parameters follows.
711 Specify the top left corner coordinates of the logo. They must be
715 Specify the width and height of the logo to clear. They must be
719 Specify the thickness of the fuzzy edge of the rectangle (added to
720 @var{w} and @var{h}). The default value is 4.
723 When set to 1, a green rectangle is drawn on the screen to simplify
724 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
725 @var{band} is set to 4. The default value is 0.
729 Some examples follow.
734 Set a rectangle covering the area with top left corner coordinates 0,0
735 and size 100x77, setting a band of size 10:
741 As the previous example, but use named options:
743 delogo=x=0:y=0:w=100:h=77:band=10
750 Attempt to fix small changes in horizontal and/or vertical shift. This
751 filter helps remove camera shake from hand-holding a camera, bumping a
752 tripod, moving on a vehicle, etc.
754 The filter accepts parameters as a string of the form
755 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
757 A description of the accepted parameters follows.
762 Specify a rectangular area where to limit the sarch for motion
764 If desired the search for motion vectors can be limited to a
765 rectangular area of the frame defined by its top left corner, width
766 and height. These parameters have the same meaning as the drawbox
767 filter which can be used to visualise the position of the bounding
770 This is useful when simultaneous movement of subjects within the frame
771 might be confused for camera motion by the motion vector search.
773 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
774 then the full frame is used. This allows later options to be set
775 without specifying the bounding box for the motion vector search.
777 Default - search the whole frame.
780 Specify the maximum extent of movement in x and y directions in the
781 range 0-64 pixels. Default 16.
784 Specify how to generate pixels to fill blanks at the edge of the
785 frame. An integer from 0 to 3 as follows:
788 Fill zeroes at blank locations
790 Original image at blank locations
792 Extruded edge value at blank locations
794 Mirrored edge at blank locations
797 The default setting is mirror edge at blank locations.
800 Specify the blocksize to use for motion search. Range 4-128 pixels,
804 Specify the contrast threshold for blocks. Only blocks with more than
805 the specified contrast (difference between darkest and lightest
806 pixels) will be considered. Range 1-255, default 125.
809 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
810 search. Default - exhaustive search.
813 If set then a detailed log of the motion search is written to the
820 Draw a colored box on the input image.
822 It accepts the syntax:
824 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
830 Specify the top left corner coordinates of the box. Default to 0.
833 Specify the width and height of the box, if 0 they are interpreted as
834 the input width and height. Default to 0.
837 Specify the color of the box to write, it can be the name of a color
838 (case insensitive match) or a 0xRRGGBB[AA] sequence.
841 Follow some examples:
843 # draw a black box around the edge of the input image
846 # draw a box with color red and an opacity of 50%
847 drawbox=10:20:200:60:red@@0.5"
852 Draw text string or text from specified file on top of video using the
855 To enable compilation of this filter you need to configure FFmpeg with
856 @code{--enable-libfreetype}.
858 The filter also recognizes strftime() sequences in the provided text
859 and expands them accordingly. Check the documentation of strftime().
861 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
864 The description of the accepted parameters follows.
869 The font file to be used for drawing text. Path must be included.
870 This parameter is mandatory.
873 The text string to be drawn. The text must be a sequence of UTF-8
875 This parameter is mandatory if no file is specified with the parameter
879 A text file containing text to be drawn. The text must be a sequence
880 of UTF-8 encoded characters.
882 This parameter is mandatory if no text string is specified with the
883 parameter @var{text}.
885 If both text and textfile are specified, an error is thrown.
888 The expressions which specify the offsets where text will be drawn
889 within the video frame. They are relative to the top/left border of the
892 The default value of @var{x} and @var{y} is "0".
894 See below for the list of accepted constants.
897 The font size to be used for drawing text.
898 The default value of @var{fontsize} is 16.
901 The color to be used for drawing fonts.
902 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
903 (e.g. "0xff000033"), possibly followed by an alpha specifier.
904 The default value of @var{fontcolor} is "black".
907 The color to be used for drawing box around text.
908 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
909 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
910 The default value of @var{boxcolor} is "white".
913 Used to draw a box around text using background color.
914 Value should be either 1 (enable) or 0 (disable).
915 The default value of @var{box} is 0.
917 @item shadowx, shadowy
918 The x and y offsets for the text shadow position with respect to the
919 position of the text. They can be either positive or negative
920 values. Default value for both is "0".
923 The color to be used for drawing a shadow behind the drawn text. It
924 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
925 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
926 The default value of @var{shadowcolor} is "black".
929 Flags to be used for loading the fonts.
931 The flags map the corresponding flags supported by libfreetype, and are
932 a combination of the following values:
939 @item vertical_layout
943 @item ignore_global_advance_width
945 @item ignore_transform
952 Default value is "render".
954 For more information consult the documentation for the FT_LOAD_*
958 The size in number of spaces to use for rendering the tab.
962 The parameters for @var{x} and @var{y} are expressions containing the
967 the input width and heigth
970 the width of the rendered text
973 the height of the rendered text
976 the height of each text line
979 input sample aspect ratio
982 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
985 horizontal and vertical chroma subsample values. For example for the
986 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
989 maximum glyph width, that is the maximum width for all the glyphs
990 contained in the rendered text
993 maximum glyph height, that is the maximum height for all the glyphs
994 contained in the rendered text, it is equivalent to @var{ascent} -
997 @item max_glyph_a, ascent
999 the maximum distance from the baseline to the highest/upper grid
1000 coordinate used to place a glyph outline point, for all the rendered
1002 It is a positive value, due to the grid's orientation with the Y axis
1005 @item max_glyph_d, descent
1006 the maximum distance from the baseline to the lowest grid coordinate
1007 used to place a glyph outline point, for all the rendered glyphs.
1008 This is a negative value, due to the grid's orientation, with the Y axis
1012 the number of input frame, starting from 0
1015 timestamp expressed in seconds, NAN if the input timestamp is unknown
1018 Some examples follow.
1023 Draw "Test Text" with font FreeSerif, using the default values for the
1024 optional parameters.
1027 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1031 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
1032 and y=50 (counting from the top-left corner of the screen), text is
1033 yellow with a red box around it. Both the text and the box have an
1037 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1038 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1041 Note that the double quotes are not necessary if spaces are not used
1042 within the parameter list.
1045 Show the text at the center of the video frame:
1047 drawtext=fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
1051 Show a text line sliding from right to left in the last row of the video
1052 frame. The file @file{LONG_LINE} is assumed to contain a single line
1055 drawtext=fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t
1059 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
1061 drawtext=fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
1065 Draw a single green letter "g", at the center of the input video.
1066 The glyph baseline is placed at half screen height.
1068 drawtext=fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent
1073 For more information about libfreetype, check:
1074 @url{http://www.freetype.org/}.
1078 Apply fade-in/out effect to input video.
1080 It accepts the parameters:
1081 @var{type}:@var{start_frame}:@var{nb_frames}
1083 @var{type} specifies if the effect type, can be either "in" for
1084 fade-in, or "out" for a fade-out effect.
1086 @var{start_frame} specifies the number of the start frame for starting
1087 to apply the fade effect.
1089 @var{nb_frames} specifies the number of frames for which the fade
1090 effect has to last. At the end of the fade-in effect the output video
1091 will have the same intensity as the input video, at the end of the
1092 fade-out transition the output video will be completely black.
1094 A few usage examples follow, usable too as test scenarios.
1096 # fade in first 30 frames of video
1099 # fade out last 45 frames of a 200-frame video
1102 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
1103 fade=in:0:25, fade=out:975:25
1105 # make first 5 frames black, then fade in from frame 5-24
1111 Transform the field order of the input video.
1113 It accepts one parameter which specifies the required field order that
1114 the input interlaced video will be transformed to. The parameter can
1115 assume one of the following values:
1119 output bottom field first
1121 output top field first
1124 Default value is "tff".
1126 Transformation is achieved by shifting the picture content up or down
1127 by one line, and filling the remaining line with appropriate picture content.
1128 This method is consistent with most broadcast field order converters.
1130 If the input video is not flagged as being interlaced, or it is already
1131 flagged as being of the required output field order then this filter does
1132 not alter the incoming video.
1134 This filter is very useful when converting to or from PAL DV material,
1135 which is bottom field first.
1139 ./ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
1144 Buffer input images and send them when they are requested.
1146 This filter is mainly useful when auto-inserted by the libavfilter
1149 The filter does not take parameters.
1153 Convert the input video to one of the specified pixel formats.
1154 Libavfilter will try to pick one that is supported for the input to
1157 The filter accepts a list of pixel format names, separated by ":",
1158 for example "yuv420p:monow:rgb24".
1160 Some examples follow:
1162 # convert the input video to the format "yuv420p"
1165 # convert the input video to any of the formats in the list
1166 format=yuv420p:yuv444p:yuv410p
1172 Apply a frei0r effect to the input video.
1174 To enable compilation of this filter you need to install the frei0r
1175 header and configure FFmpeg with --enable-frei0r.
1177 The filter supports the syntax:
1179 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
1182 @var{filter_name} is the name to the frei0r effect to load. If the
1183 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
1184 is searched in each one of the directories specified by the colon
1185 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
1186 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
1187 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
1189 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
1190 for the frei0r effect.
1192 A frei0r effect parameter can be a boolean (whose values are specified
1193 with "y" and "n"), a double, a color (specified by the syntax
1194 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1195 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1196 description), a position (specified by the syntax @var{X}/@var{Y},
1197 @var{X} and @var{Y} being float numbers) and a string.
1199 The number and kind of parameters depend on the loaded effect. If an
1200 effect parameter is not specified the default value is set.
1202 Some examples follow:
1204 # apply the distort0r effect, set the first two double parameters
1205 frei0r=distort0r:0.5:0.01
1207 # apply the colordistance effect, takes a color as first parameter
1208 frei0r=colordistance:0.2/0.3/0.4
1209 frei0r=colordistance:violet
1210 frei0r=colordistance:0x112233
1212 # apply the perspective effect, specify the top left and top right
1214 frei0r=perspective:0.2/0.2:0.8/0.2
1217 For more information see:
1218 @url{http://piksel.org/frei0r}
1222 Fix the banding artifacts that are sometimes introduced into nearly flat
1223 regions by truncation to 8bit colordepth.
1224 Interpolate the gradients that should go where the bands are, and
1227 This filter is designed for playback only. Do not use it prior to
1228 lossy compression, because compression tends to lose the dither and
1229 bring back the bands.
1231 The filter takes two optional parameters, separated by ':':
1232 @var{strength}:@var{radius}
1234 @var{strength} is the maximum amount by which the filter will change
1235 any one pixel. Also the threshold for detecting nearly flat
1236 regions. Acceptable values range from .51 to 255, default value is
1237 1.2, out-of-range values will be clipped to the valid range.
1239 @var{radius} is the neighborhood to fit the gradient to. A larger
1240 radius makes for smoother gradients, but also prevents the filter from
1241 modifying the pixels near detailed regions. Acceptable values are
1242 8-32, default value is 16, out-of-range values will be clipped to the
1246 # default parameters
1255 Flip the input video horizontally.
1257 For example to horizontally flip the video in input with
1260 ffmpeg -i in.avi -vf "hflip" out.avi
1265 High precision/quality 3d denoise filter. This filter aims to reduce
1266 image noise producing smooth images and making still images really
1267 still. It should enhance compressibility.
1269 It accepts the following optional parameters:
1270 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
1274 a non-negative float number which specifies spatial luma strength,
1277 @item chroma_spatial
1278 a non-negative float number which specifies spatial chroma strength,
1279 defaults to 3.0*@var{luma_spatial}/4.0
1282 a float number which specifies luma temporal strength, defaults to
1283 6.0*@var{luma_spatial}/4.0
1286 a float number which specifies chroma temporal strength, defaults to
1287 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1290 @section lut, lutrgb, lutyuv
1292 Compute a look-up table for binding each pixel component input value
1293 to an output value, and apply it to input video.
1295 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1296 to an RGB input video.
1298 These filters accept in input a ":"-separated list of options, which
1299 specify the expressions used for computing the lookup table for the
1300 corresponding pixel component values.
1302 The @var{lut} filter requires either YUV or RGB pixel formats in
1303 input, and accepts the options:
1306 first pixel component
1308 second pixel component
1310 third pixel component
1312 fourth pixel component, corresponds to the alpha component
1315 The exact component associated to each option depends on the format in
1318 The @var{lutrgb} filter requires RGB pixel formats in input, and
1319 accepts the options:
1331 The @var{lutyuv} filter requires YUV pixel formats in input, and
1332 accepts the options:
1335 Y/luminance component
1344 The expressions can contain the following constants and functions:
1348 the input width and heigth
1351 input value for the pixel component
1354 the input value clipped in the @var{minval}-@var{maxval} range
1357 maximum value for the pixel component
1360 minimum value for the pixel component
1363 the negated value for the pixel component value clipped in the
1364 @var{minval}-@var{maxval} range , it corresponds to the expression
1365 "maxval-clipval+minval"
1368 the computed value in @var{val} clipped in the
1369 @var{minval}-@var{maxval} range
1371 @item gammaval(gamma)
1372 the computed gamma correction value of the pixel component value
1373 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1375 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1379 All expressions default to "val".
1381 Some examples follow:
1383 # negate input video
1384 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1385 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1387 # the above is the same as
1388 lutrgb="r=negval:g=negval:b=negval"
1389 lutyuv="y=negval:u=negval:v=negval"
1394 # remove chroma components, turns the video into a graytone image
1395 lutyuv="u=128:v=128"
1397 # apply a luma burning effect
1400 # remove green and blue components
1403 # set a constant alpha channel value on input
1404 format=rgba,lutrgb=a="maxval-minval/2"
1406 # correct luminance gamma by a 0.5 factor
1407 lutyuv=y=gammaval(0.5)
1412 Apply an MPlayer filter to the input video.
1414 This filter provides a wrapper around most of the filters of
1417 This wrapper is considered experimental. Some of the wrapped filters
1418 may not work properly and we may drop support for them, as they will
1419 be implemented natively into FFmpeg. Thus you should avoid
1420 depending on them when writing portable scripts.
1422 The filters accepts the parameters:
1423 @var{filter_name}[:=]@var{filter_params}
1425 @var{filter_name} is the name of a supported MPlayer filter,
1426 @var{filter_params} is a string containing the parameters accepted by
1429 The list of the currently supported filters follows:
1483 The parameter syntax and behavior for the listed filters are the same
1484 of the corresponding MPlayer filters. For detailed instructions check
1485 the "VIDEO FILTERS" section in the MPlayer manual.
1487 Some examples follow:
1489 # remove a logo by interpolating the surrounding pixels
1490 mp=delogo=200:200:80:20:1
1492 # adjust gamma, brightness, contrast
1495 # tweak hue and saturation
1499 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
1505 This filter accepts an integer in input, if non-zero it negates the
1506 alpha component (if available). The default value in input is 0.
1510 Force libavfilter not to use any of the specified pixel formats for the
1511 input to the next filter.
1513 The filter accepts a list of pixel format names, separated by ":",
1514 for example "yuv420p:monow:rgb24".
1516 Some examples follow:
1518 # force libavfilter to use a format different from "yuv420p" for the
1519 # input to the vflip filter
1520 noformat=yuv420p,vflip
1522 # convert the input video to any of the formats not contained in the list
1523 noformat=yuv420p:yuv444p:yuv410p
1528 Pass the video source unchanged to the output.
1532 Apply video transform using libopencv.
1534 To enable this filter install libopencv library and headers and
1535 configure FFmpeg with --enable-libopencv.
1537 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1539 @var{filter_name} is the name of the libopencv filter to apply.
1541 @var{filter_params} specifies the parameters to pass to the libopencv
1542 filter. If not specified the default values are assumed.
1544 Refer to the official libopencv documentation for more precise
1546 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1548 Follows the list of supported libopencv filters.
1553 Dilate an image by using a specific structuring element.
1554 This filter corresponds to the libopencv function @code{cvDilate}.
1556 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1558 @var{struct_el} represents a structuring element, and has the syntax:
1559 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1561 @var{cols} and @var{rows} represent the number of colums and rows of
1562 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1563 point, and @var{shape} the shape for the structuring element, and
1564 can be one of the values "rect", "cross", "ellipse", "custom".
1566 If the value for @var{shape} is "custom", it must be followed by a
1567 string of the form "=@var{filename}". The file with name
1568 @var{filename} is assumed to represent a binary image, with each
1569 printable character corresponding to a bright pixel. When a custom
1570 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1571 or columns and rows of the read file are assumed instead.
1573 The default value for @var{struct_el} is "3x3+0x0/rect".
1575 @var{nb_iterations} specifies the number of times the transform is
1576 applied to the image, and defaults to 1.
1578 Follow some example:
1580 # use the default values
1583 # dilate using a structuring element with a 5x5 cross, iterate two times
1584 ocv=dilate=5x5+2x2/cross:2
1586 # read the shape from the file diamond.shape, iterate two times
1587 # the file diamond.shape may contain a pattern of characters like this:
1593 # the specified cols and rows are ignored (but not the anchor point coordinates)
1594 ocv=0x0+2x2/custom=diamond.shape:2
1599 Erode an image by using a specific structuring element.
1600 This filter corresponds to the libopencv function @code{cvErode}.
1602 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1603 with the same syntax and semantics as the @ref{dilate} filter.
1607 Smooth the input video.
1609 The filter takes the following parameters:
1610 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1612 @var{type} is the type of smooth filter to apply, and can be one of
1613 the following values: "blur", "blur_no_scale", "median", "gaussian",
1614 "bilateral". The default value is "gaussian".
1616 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1617 parameters whose meanings depend on smooth type. @var{param1} and
1618 @var{param2} accept integer positive values or 0, @var{param3} and
1619 @var{param4} accept float values.
1621 The default value for @var{param1} is 3, the default value for the
1622 other parameters is 0.
1624 These parameters correspond to the parameters assigned to the
1625 libopencv function @code{cvSmooth}.
1629 Overlay one video on top of another.
1631 It takes two inputs and one output, the first input is the "main"
1632 video on which the second input is overlayed.
1634 It accepts the parameters: @var{x}:@var{y}[:@var{options}].
1636 @var{x} is the x coordinate of the overlayed video on the main video,
1637 @var{y} is the y coordinate. @var{x} and @var{y} are expressions containing
1638 the following parameters:
1641 @item main_w, main_h
1642 main input width and height
1645 same as @var{main_w} and @var{main_h}
1647 @item overlay_w, overlay_h
1648 overlay input width and height
1651 same as @var{overlay_w} and @var{overlay_h}
1654 @var{options} is an optional list of @var{key}=@var{value} pairs,
1657 The description of the accepted options follows.
1661 If set to 1, force the filter to accept inputs in the RGB
1662 colorspace. Default value is 0.
1665 Be aware that frames are taken from each input video in timestamp
1666 order, hence, if their initial timestamps differ, it is a a good idea
1667 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1668 have them begin in the same zero timestamp, as it does the example for
1669 the @var{movie} filter.
1671 Follow some examples:
1673 # draw the overlay at 10 pixels from the bottom right
1674 # corner of the main video.
1675 overlay=main_w-overlay_w-10:main_h-overlay_h-10
1677 # insert a transparent PNG logo in the bottom left corner of the input
1678 movie=logo.png [logo];
1679 [in][logo] overlay=10:main_h-overlay_h-10 [out]
1681 # insert 2 different transparent PNG logos (second logo on bottom
1683 movie=logo1.png [logo1];
1684 movie=logo2.png [logo2];
1685 [in][logo1] overlay=10:H-h-10 [in+logo1];
1686 [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
1688 # add a transparent color layer on top of the main video,
1689 # WxH specifies the size of the main input to the overlay filter
1690 color=red@.3:WxH [over]; [in][over] overlay [out]
1693 You can chain togheter more overlays but the efficiency of such
1694 approach is yet to be tested.
1698 Add paddings to the input image, and places the original input at the
1699 given coordinates @var{x}, @var{y}.
1701 It accepts the following parameters:
1702 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1704 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1705 expressions containing the following constants:
1709 the input video width and height
1712 same as @var{in_w} and @var{in_h}
1715 the output width and height, that is the size of the padded area as
1716 specified by the @var{width} and @var{height} expressions
1719 same as @var{out_w} and @var{out_h}
1722 x and y offsets as specified by the @var{x} and @var{y}
1723 expressions, or NAN if not yet specified
1726 same as @var{iw} / @var{ih}
1729 input sample aspect ratio
1732 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1735 horizontal and vertical chroma subsample values. For example for the
1736 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1739 Follows the description of the accepted parameters.
1744 Specify the size of the output image with the paddings added. If the
1745 value for @var{width} or @var{height} is 0, the corresponding input size
1746 is used for the output.
1748 The @var{width} expression can reference the value set by the
1749 @var{height} expression, and viceversa.
1751 The default value of @var{width} and @var{height} is 0.
1755 Specify the offsets where to place the input image in the padded area
1756 with respect to the top/left border of the output image.
1758 The @var{x} expression can reference the value set by the @var{y}
1759 expression, and viceversa.
1761 The default value of @var{x} and @var{y} is 0.
1765 Specify the color of the padded area, it can be the name of a color
1766 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1768 The default value of @var{color} is "black".
1772 Some examples follow:
1775 # Add paddings with color "violet" to the input video. Output video
1776 # size is 640x480, the top-left corner of the input video is placed at
1778 pad=640:480:0:40:violet
1780 # pad the input to get an output with dimensions increased bt 3/2,
1781 # and put the input video at the center of the padded area
1782 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1784 # pad the input to get a squared output with size equal to the maximum
1785 # value between the input width and height, and put the input video at
1786 # the center of the padded area
1787 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1789 # pad the input to get a final w/h ratio of 16:9
1790 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1792 # for anamorphic video, in order to set the output display aspect ratio,
1793 # it is necessary to use sar in the expression, according to the relation:
1794 # (ih * X / ih) * sar = output_dar
1795 # X = output_dar / sar
1796 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
1798 # double output size and put the input video in the bottom-right
1799 # corner of the output padded area
1800 pad="2*iw:2*ih:ow-iw:oh-ih"
1803 @section pixdesctest
1805 Pixel format descriptor test filter, mainly useful for internal
1806 testing. The output video should be equal to the input video.
1810 format=monow, pixdesctest
1813 can be used to test the monowhite pixel format descriptor definition.
1817 Scale the input video to @var{width}:@var{height}[:@var{interl}=@{1|-1@}] and/or convert the image format.
1819 The parameters @var{width} and @var{height} are expressions containing
1820 the following constants:
1824 the input width and height
1827 same as @var{in_w} and @var{in_h}
1830 the output (cropped) width and height
1833 same as @var{out_w} and @var{out_h}
1836 same as @var{iw} / @var{ih}
1839 input sample aspect ratio
1842 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1845 input sample aspect ratio
1848 horizontal and vertical chroma subsample values. For example for the
1849 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1852 If the input image format is different from the format requested by
1853 the next filter, the scale filter will convert the input to the
1856 If the value for @var{width} or @var{height} is 0, the respective input
1857 size is used for the output.
1859 If the value for @var{width} or @var{height} is -1, the scale filter will
1860 use, for the respective output size, a value that maintains the aspect
1861 ratio of the input image.
1863 The default value of @var{width} and @var{height} is 0.
1865 Valid values for the optional parameter @var{interl} are:
1869 force interlaced aware scaling
1872 select interlaced aware scaling depending on whether the source frames
1873 are flagged as interlaced or not
1876 Some examples follow:
1878 # scale the input video to a size of 200x100.
1881 # scale the input to 2x
1883 # the above is the same as
1886 # scale the input to half size
1889 # increase the width, and set the height to the same size
1892 # seek for Greek harmony
1896 # increase the height, and set the width to 3/2 of the height
1899 # increase the size, but make the size a multiple of the chroma
1900 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1902 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1903 scale='min(500\, iw*3/2):-1'
1907 Select frames to pass in output.
1909 It accepts in input an expression, which is evaluated for each input
1910 frame. If the expression is evaluated to a non-zero value, the frame
1911 is selected and passed to the output, otherwise it is discarded.
1913 The expression can contain the following constants:
1917 the sequential number of the filtered frame, starting from 0
1920 the sequential number of the selected frame, starting from 0
1922 @item prev_selected_n
1923 the sequential number of the last selected frame, NAN if undefined
1926 timebase of the input timestamps
1929 the PTS (Presentation TimeStamp) of the filtered video frame,
1930 expressed in @var{TB} units, NAN if undefined
1933 the PTS (Presentation TimeStamp) of the filtered video frame,
1934 expressed in seconds, NAN if undefined
1937 the PTS of the previously filtered video frame, NAN if undefined
1939 @item prev_selected_pts
1940 the PTS of the last previously filtered video frame, NAN if undefined
1942 @item prev_selected_t
1943 the PTS of the last previously selected video frame, NAN if undefined
1946 the PTS of the first video frame in the video, NAN if undefined
1949 the time of the first video frame in the video, NAN if undefined
1952 the type of the filtered frame, can assume one of the following
1964 @item interlace_type
1965 the frame interlace type, can assume one of the following values:
1968 the frame is progressive (not interlaced)
1970 the frame is top-field-first
1972 the frame is bottom-field-first
1976 1 if the filtered frame is a key-frame, 0 otherwise
1979 the position in the file of the filtered frame, -1 if the information
1980 is not available (e.g. for synthetic video)
1983 The default value of the select expression is "1".
1985 Some examples follow:
1988 # select all frames in input
1991 # the above is the same as:
1997 # select only I-frames
1998 select='eq(pict_type\,I)'
2000 # select one frame every 100
2001 select='not(mod(n\,100))'
2003 # select only frames contained in the 10-20 time interval
2004 select='gte(t\,10)*lte(t\,20)'
2006 # select only I frames contained in the 10-20 time interval
2007 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2009 # select frames with a minimum distance of 10 seconds
2010 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2016 Set the Display Aspect Ratio for the filter output video.
2018 This is done by changing the specified Sample (aka Pixel) Aspect
2019 Ratio, according to the following equation:
2020 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2022 Keep in mind that this filter does not modify the pixel dimensions of
2023 the video frame. Also the display aspect ratio set by this filter may
2024 be changed by later filters in the filterchain, e.g. in case of
2025 scaling or if another "setdar" or a "setsar" filter is applied.
2027 The filter accepts a parameter string which represents the wanted
2028 display aspect ratio.
2029 The parameter can be a floating point number string, or an expression
2030 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
2031 numerator and denominator of the aspect ratio.
2032 If the parameter is not specified, it is assumed the value "0:1".
2034 For example to change the display aspect ratio to 16:9, specify:
2037 # the above is equivalent to
2041 See also the @ref{setsar} filter documentation.
2045 Change the PTS (presentation timestamp) of the input video frames.
2047 Accept in input an expression evaluated through the eval API, which
2048 can contain the following constants:
2052 the presentation timestamp in input
2055 the count of the input frame, starting from 0.
2058 the PTS of the first video frame
2061 tell if the current frame is interlaced
2064 original position in the file of the frame, or undefined if undefined
2065 for the current frame
2075 Some examples follow:
2078 # start counting PTS from zero
2090 # fixed rate 25 fps with some jitter
2091 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
2097 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
2099 Note that as a consequence of the application of this filter, the
2100 output display aspect ratio will change according to the following
2102 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2104 Keep in mind that the sample aspect ratio set by this filter may be
2105 changed by later filters in the filterchain, e.g. if another "setsar"
2106 or a "setdar" filter is applied.
2108 The filter accepts a parameter string which represents the wanted
2109 sample aspect ratio.
2110 The parameter can be a floating point number string, or an expression
2111 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
2112 numerator and denominator of the aspect ratio.
2113 If the parameter is not specified, it is assumed the value "0:1".
2115 For example to change the sample aspect ratio to 10:11, specify:
2122 Set the timebase to use for the output frames timestamps.
2123 It is mainly useful for testing timebase configuration.
2125 It accepts in input an arithmetic expression representing a rational.
2126 The expression can contain the constants "AVTB" (the
2127 default timebase), and "intb" (the input timebase).
2129 The default value for the input is "intb".
2131 Follow some examples.
2134 # set the timebase to 1/25
2137 # set the timebase to 1/10
2140 #set the timebase to 1001/1000
2143 #set the timebase to 2*intb
2146 #set the default timebase value
2152 Show a line containing various information for each input video frame.
2153 The input video is not modified.
2155 The shown line contains a sequence of key/value pairs of the form
2156 @var{key}:@var{value}.
2158 A description of each shown parameter follows:
2162 sequential number of the input frame, starting from 0
2165 Presentation TimeStamp of the input frame, expressed as a number of
2166 time base units. The time base unit depends on the filter input pad.
2169 Presentation TimeStamp of the input frame, expressed as a number of
2173 position of the frame in the input stream, -1 if this information in
2174 unavailable and/or meanigless (for example in case of synthetic video)
2180 sample aspect ratio of the input frame, expressed in the form
2184 size of the input frame, expressed in the form
2185 @var{width}x@var{height}
2188 interlaced mode ("P" for "progressive", "T" for top field first, "B"
2189 for bottom field first)
2192 1 if the frame is a key frame, 0 otherwise
2195 picture type of the input frame ("I" for an I-frame, "P" for a
2196 P-frame, "B" for a B-frame, "?" for unknown type).
2197 Check also the documentation of the @code{AVPictureType} enum and of
2198 the @code{av_get_picture_type_char} function defined in
2199 @file{libavutil/avutil.h}.
2202 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
2204 @item plane_checksum
2205 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
2206 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
2211 Pass the images of input video on to next video filter as multiple
2215 ./ffmpeg -i in.avi -vf "slicify=32" out.avi
2218 The filter accepts the slice height as parameter. If the parameter is
2219 not specified it will use the default value of 16.
2221 Adding this in the beginning of filter chains should make filtering
2222 faster due to better use of the memory cache.
2226 Pass on the input video to two outputs. Both outputs are identical to
2231 [in] split [splitout1][splitout2];
2232 [splitout1] crop=100:100:0:0 [cropout];
2233 [splitout2] pad=200:200:100:100 [padout];
2236 will create two separate outputs from the same input, one cropped and
2241 Transpose rows with columns in the input video and optionally flip it.
2243 It accepts a parameter representing an integer, which can assume the
2248 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2256 Rotate by 90 degrees clockwise, that is:
2264 Rotate by 90 degrees counterclockwise, that is:
2272 Rotate by 90 degrees clockwise and vertically flip, that is:
2282 Sharpen or blur the input video.
2284 It accepts the following parameters:
2285 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
2287 Negative values for the amount will blur the input video, while positive
2288 values will sharpen. All parameters are optional and default to the
2289 equivalent of the string '5:5:1.0:5:5:0.0'.
2294 Set the luma matrix horizontal size. It can be an integer between 3
2295 and 13, default value is 5.
2298 Set the luma matrix vertical size. It can be an integer between 3
2299 and 13, default value is 5.
2302 Set the luma effect strength. It can be a float number between -2.0
2303 and 5.0, default value is 1.0.
2305 @item chroma_msize_x
2306 Set the chroma matrix horizontal size. It can be an integer between 3
2307 and 13, default value is 5.
2309 @item chroma_msize_y
2310 Set the chroma matrix vertical size. It can be an integer between 3
2311 and 13, default value is 5.
2314 Set the chroma effect strength. It can be a float number between -2.0
2315 and 5.0, default value is 0.0.
2320 # Strong luma sharpen effect parameters
2323 # Strong blur of both luma and chroma parameters
2324 unsharp=7:7:-2:7:7:-2
2326 # Use the default values with @command{ffmpeg}
2327 ./ffmpeg -i in.avi -vf "unsharp" out.mp4
2332 Flip the input video vertically.
2335 ./ffmpeg -i in.avi -vf "vflip" out.avi
2340 Deinterlace the input video ("yadif" means "yet another deinterlacing
2343 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
2345 @var{mode} specifies the interlacing mode to adopt, accepts one of the
2350 output 1 frame for each frame
2352 output 1 frame for each field
2354 like 0 but skips spatial interlacing check
2356 like 1 but skips spatial interlacing check
2361 @var{parity} specifies the picture field parity assumed for the input
2362 interlaced video, accepts one of the following values:
2366 assume top field first
2368 assume bottom field first
2370 enable automatic detection
2373 Default value is -1.
2374 If interlacing is unknown or decoder does not export this information,
2375 top field first will be assumed.
2377 @var{auto} specifies if deinterlacer should trust the interlaced flag
2378 and only deinterlace frames marked as interlaced
2382 deinterlace all frames
2384 only deinterlace frames marked as interlaced
2389 @c man end VIDEO FILTERS
2391 @chapter Video Sources
2392 @c man begin VIDEO SOURCES
2394 Below is a description of the currently available video sources.
2398 Buffer video frames, and make them available to the filter chain.
2400 This source is mainly intended for a programmatic use, in particular
2401 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2403 It accepts the following parameters:
2404 @var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}:@var{scale_params}
2406 All the parameters but @var{scale_params} need to be explicitely
2409 Follows the list of the accepted parameters.
2414 Specify the width and height of the buffered video frames.
2416 @item pix_fmt_string
2417 A string representing the pixel format of the buffered video frames.
2418 It may be a number corresponding to a pixel format, or a pixel format
2421 @item timebase_num, timebase_den
2422 Specify numerator and denomitor of the timebase assumed by the
2423 timestamps of the buffered frames.
2425 @item sample_aspect_ratio.num, sample_aspect_ratio.den
2426 Specify numerator and denominator of the sample aspect ratio assumed
2427 by the video frames.
2430 Specify the optional parameters to be used for the scale filter which
2431 is automatically inserted when an input change is detected in the
2432 input size or format.
2437 buffer=320:240:yuv410p:1:24:1:1
2440 will instruct the source to accept video frames with size 320x240 and
2441 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2442 square pixels (1:1 sample aspect ratio).
2443 Since the pixel format with name "yuv410p" corresponds to the number 6
2444 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
2445 this example corresponds to:
2447 buffer=320:240:6:1:24:1:1
2452 Provide an uniformly colored input.
2454 It accepts the following parameters:
2455 @var{color}:@var{frame_size}:@var{frame_rate}
2457 Follows the description of the accepted parameters.
2462 Specify the color of the source. It can be the name of a color (case
2463 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2464 alpha specifier. The default value is "black".
2467 Specify the size of the sourced video, it may be a string of the form
2468 @var{width}x@var{height}, or the name of a size abbreviation. The
2469 default value is "320x240".
2472 Specify the frame rate of the sourced video, as the number of frames
2473 generated per second. It has to be a string in the format
2474 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2475 number or a valid video frame rate abbreviation. The default value is
2480 For example the following graph description will generate a red source
2481 with an opacity of 0.2, with size "qcif" and a frame rate of 10
2482 frames per second, which will be overlayed over the source connected
2483 to the pad with identifier "in".
2486 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2491 Read a video stream from a movie container.
2493 It accepts the syntax: @var{movie_name}[:@var{options}] where
2494 @var{movie_name} is the name of the resource to read (not necessarily
2495 a file but also a device or a stream accessed through some protocol),
2496 and @var{options} is an optional sequence of @var{key}=@var{value}
2497 pairs, separated by ":".
2499 The description of the accepted options follows.
2503 @item format_name, f
2504 Specifies the format assumed for the movie to read, and can be either
2505 the name of a container or an input device. If not specified the
2506 format is guessed from @var{movie_name} or by probing.
2508 @item seek_point, sp
2509 Specifies the seek point in seconds, the frames will be output
2510 starting from this seek point, the parameter is evaluated with
2511 @code{av_strtod} so the numerical value may be suffixed by an IS
2512 postfix. Default value is "0".
2514 @item stream_index, si
2515 Specifies the index of the video stream to read. If the value is -1,
2516 the best suited video stream will be automatically selected. Default
2521 This filter allows to overlay a second video on top of main input of
2522 a filtergraph as shown in this graph:
2524 input -----------> deltapts0 --> overlay --> output
2527 movie --> scale--> deltapts1 -------+
2530 Some examples follow:
2532 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
2533 # on top of the input labelled as "in".
2534 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2535 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2537 # read from a video4linux2 device, and overlay it on top of the input
2539 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2540 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2546 Generate various test patterns, as generated by the MPlayer test filter.
2548 The size of the generated video is fixed, and is 256x256.
2549 This source is useful in particular for testing encoding features.
2551 This source accepts an optional sequence of @var{key}=@var{value} pairs,
2552 separated by ":". The description of the accepted options follows.
2557 Specify the frame rate of the sourced video, as the number of frames
2558 generated per second. It has to be a string in the format
2559 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2560 number or a valid video frame rate abbreviation. The default value is
2564 Set the video duration of the sourced video. The accepted syntax is:
2566 [-]HH[:MM[:SS[.m...]]]
2569 See also the function @code{av_parse_time()}.
2571 If not specified, or the expressed duration is negative, the video is
2572 supposed to be generated forever.
2576 Set the number or the name of the test to perform. Supported tests are:
2591 Default value is "all", which will cycle through the list of all tests.
2594 For example the following:
2599 will generate a "dc_luma" test pattern.
2603 Provide a frei0r source.
2605 To enable compilation of this filter you need to install the frei0r
2606 header and configure FFmpeg with --enable-frei0r.
2608 The source supports the syntax:
2610 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
2613 @var{size} is the size of the video to generate, may be a string of the
2614 form @var{width}x@var{height} or a frame size abbreviation.
2615 @var{rate} is the rate of the video to generate, may be a string of
2616 the form @var{num}/@var{den} or a frame rate abbreviation.
2617 @var{src_name} is the name to the frei0r source to load. For more
2618 information regarding frei0r and how to set the parameters read the
2619 section @ref{frei0r} in the description of the video filters.
2621 Some examples follow:
2623 # generate a frei0r partik0l source with size 200x200 and framerate 10
2624 # which is overlayed on the overlay filter main input
2625 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
2628 @section nullsrc, rgbtestsrc, testsrc
2630 The @code{nullsrc} source returns unprocessed video frames. It is
2631 mainly useful to be employed in analysis / debugging tools, or as the
2632 source for filters which ignore the input data.
2634 The @code{rgbtestsrc} source generates an RGB test pattern useful for
2635 detecting RGB vs BGR issues. You should see a red, green and blue
2636 stripe from top to bottom.
2638 The @code{testsrc} source generates a test video pattern, showing a
2639 color pattern, a scrolling gradient and a timestamp. This is mainly
2640 intended for testing purposes.
2642 These sources accept an optional sequence of @var{key}=@var{value} pairs,
2643 separated by ":". The description of the accepted options follows.
2648 Specify the size of the sourced video, it may be a string of the form
2649 @var{width}x@var{heigth}, or the name of a size abbreviation. The
2650 default value is "320x240".
2653 Specify the frame rate of the sourced video, as the number of frames
2654 generated per second. It has to be a string in the format
2655 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2656 number or a valid video frame rate abbreviation. The default value is
2660 Set the sample aspect ratio of the sourced video.
2663 Set the video duration of the sourced video. The accepted syntax is:
2665 [-]HH[:MM[:SS[.m...]]]
2668 See also the function @code{av_parse_time()}.
2670 If not specified, or the expressed duration is negative, the video is
2671 supposed to be generated forever.
2674 For example the following:
2676 testsrc=duration=5.3:size=qcif:rate=10
2679 will generate a video with a duration of 5.3 seconds, with size
2680 176x144 and a framerate of 10 frames per second.
2682 If the input content is to be ignored, @code{nullsrc} can be used. The
2683 following command generates noise in the luminance plane by employing
2684 the @code{mp=geq} filter:
2686 nullsrc=s=256x256, mp=geq=random(1)*255:128:128
2689 @c man end VIDEO SOURCES
2691 @chapter Video Sinks
2692 @c man begin VIDEO SINKS
2694 Below is a description of the currently available video sinks.
2698 Buffer video frames, and make them available to the end of the filter
2701 This sink is mainly intended for a programmatic use, in particular
2702 through the interface defined in @file{libavfilter/buffersink.h}.
2704 It does not require a string parameter in input, but you need to
2705 specify a pointer to a list of supported pixel formats terminated by
2706 -1 in the opaque parameter provided to @code{avfilter_init_filter}
2707 when initializing this sink.
2711 Null video sink, do absolutely nothing with the input video. It is
2712 mainly useful as a template and to be employed in analysis / debugging
2715 @c man end VIDEO SINKS