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/audioconvert.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 meaningless (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}
229 Make audio easier to listen to on headphones.
231 This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio
232 so that when listened to on headphones the stereo image is moved from
233 inside your head (standard for headphones) to outside and in front of
234 the listener (standard for speakers).
240 Adjust the input audio volume.
242 The filter accepts exactly one parameter @var{vol}, which expresses
243 how the audio volume will be increased or decreased.
245 Output values are clipped to the maximum value.
247 If @var{vol} is expressed as a decimal number, and the output audio
248 volume is given by the relation:
250 @var{output_volume} = @var{vol} * @var{input_volume}
253 If @var{vol} is expressed as a decimal number followed by the string
254 "dB", the value represents the requested change in decibels of the
255 input audio power, and the output audio volume is given by the
258 @var{output_volume} = 10^(@var{vol}/20) * @var{input_volume}
261 Otherwise @var{vol} is considered an expression and its evaluated
262 value is used for computing the output audio volume according to the
265 Default value for @var{vol} is 1.0.
271 Half the input audio volume:
276 The above example is equivalent to:
282 Decrease input audio power by 12 decibels:
288 @c man end AUDIO FILTERS
290 @chapter Audio Sources
291 @c man begin AUDIO SOURCES
293 Below is a description of the currently available audio sources.
297 Buffer audio frames, and make them available to the filter chain.
299 This source is mainly intended for a programmatic use, in particular
300 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
302 It accepts the following mandatory parameters:
303 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}:@var{packing}
308 The sample rate of the incoming audio buffers.
311 The sample format of the incoming audio buffers.
312 Either a sample format name or its corresponging integer representation from
313 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
316 The channel layout of the incoming audio buffers.
317 Either a channel layout name from channel_layout_map in
318 @file{libavutil/audioconvert.c} or its corresponding integer representation
319 from the AV_CH_LAYOUT_* macros in @file{libavutil/audioconvert.h}
322 Either "packed" or "planar", or their integer representation: 0 or 1
329 abuffer=44100:s16:stereo:planar
332 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
333 Since the sample format with name "s16" corresponds to the number
334 1 and the "stereo" channel layout corresponds to the value 3, this is
342 Generate an audio signal specified by an expression.
344 This source accepts in input one or more expressions (one for each
345 channel), which are evaluated and used to generate a corresponding
348 It accepts the syntax: @var{exprs}[::@var{options}].
349 @var{exprs} is a list of expressions separated by ":", one for each
350 separate channel. The output channel layout depends on the number of
351 provided expressions, up to 8 channels are supported.
353 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
356 The description of the accepted options follows.
361 Set the number of samples per channel per each output frame,
365 Specify the sample rate, default to 44100.
368 Each expression in @var{exprs} can contain the following constants:
372 number of the evaluated sample, starting from 0
375 time of the evaluated sample expressed in seconds, starting from 0
394 Generate a sin signal with frequence of 440 Hz, set sample rate to
397 aevalsrc="sin(440*2*PI*t)::s=8000"
401 Generate white noise:
403 aevalsrc="-2+random(0)"
407 Generate an amplitude modulated signal:
409 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
413 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
415 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
422 Read an audio stream from a movie container.
424 It accepts the syntax: @var{movie_name}[:@var{options}] where
425 @var{movie_name} is the name of the resource to read (not necessarily
426 a file but also a device or a stream accessed through some protocol),
427 and @var{options} is an optional sequence of @var{key}=@var{value}
428 pairs, separated by ":".
430 The description of the accepted options follows.
435 Specify the format assumed for the movie to read, and can be either
436 the name of a container or an input device. If not specified the
437 format is guessed from @var{movie_name} or by probing.
440 Specify the seek point in seconds, the frames will be output
441 starting from this seek point, the parameter is evaluated with
442 @code{av_strtod} so the numerical value may be suffixed by an IS
443 postfix. Default value is "0".
445 @item stream_index, si
446 Specify the index of the audio stream to read. If the value is -1,
447 the best suited audio stream will be automatically selected. Default
454 Null audio source, return unprocessed audio frames. It is mainly useful
455 as a template and to be employed in analysis / debugging tools, or as
456 the source for filters which ignore the input data (for example the sox
459 It accepts an optional sequence of @var{key}=@var{value} pairs,
462 The description of the accepted options follows.
467 Specify the sample rate, and defaults to 44100.
469 @item channel_layout, cl
471 Specify the channel layout, and can be either an integer or a string
472 representing a channel layout. The default value of @var{channel_layout}
475 Check the channel_layout_map definition in
476 @file{libavcodec/audioconvert.c} for the mapping between strings and
477 channel layout values.
480 Set the number of samples per requested frames.
484 Follow some examples:
486 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
487 anullsrc=r=48000:cl=4
490 anullsrc=r=48000:cl=mono
493 @c man end AUDIO SOURCES
496 @c man begin AUDIO SINKS
498 Below is a description of the currently available audio sinks.
502 Buffer audio frames, and make them available to the end of filter chain.
504 This sink is mainly intended for programmatic use, in particular
505 through the interface defined in @file{libavfilter/buffersink.h}.
507 It requires a pointer to an AVABufferSinkContext structure, which
508 defines the incoming buffers' formats, to be passed as the opaque
509 parameter to @code{avfilter_init_filter} for initialization.
513 Null audio sink, do absolutely nothing with the input audio. It is
514 mainly useful as a template and to be employed in analysis / debugging
517 @c man end AUDIO SINKS
519 @chapter Video Filters
520 @c man begin VIDEO FILTERS
522 When you configure your FFmpeg build, you can disable any of the
523 existing filters using --disable-filters.
524 The configure output will show the video filters included in your
527 Below is a description of the currently available video filters.
531 Detect frames that are (almost) completely black. Can be useful to
532 detect chapter transitions or commercials. Output lines consist of
533 the frame number of the detected frame, the percentage of blackness,
534 the position in the file if known or -1 and the timestamp in seconds.
536 In order to display the output lines, you need to set the loglevel at
537 least to the AV_LOG_INFO value.
539 The filter accepts the syntax:
541 blackframe[=@var{amount}:[@var{threshold}]]
544 @var{amount} is the percentage of the pixels that have to be below the
545 threshold, and defaults to 98.
547 @var{threshold} is the threshold below which a pixel value is
548 considered black, and defaults to 32.
552 Apply boxblur algorithm to the input video.
554 This filter accepts the parameters:
555 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
557 Chroma and alpha parameters are optional, if not specified they default
558 to the corresponding values set for @var{luma_radius} and
561 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
562 the radius in pixels of the box used for blurring the corresponding
563 input plane. They are expressions, and can contain the following
567 the input width and heigth in pixels
570 the input chroma image width and height in pixels
573 horizontal and vertical chroma subsample values. For example for the
574 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
577 The radius must be a non-negative number, and must not be greater than
578 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
579 and of @code{min(cw,ch)/2} for the chroma planes.
581 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
582 how many times the boxblur filter is applied to the corresponding
585 Some examples follow:
590 Apply a boxblur filter with luma, chroma, and alpha radius
597 Set luma radius to 2, alpha and chroma radius to 0
603 Set luma and chroma radius to a fraction of the video dimension
605 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
612 Copy the input source unchanged to the output. Mainly useful for
617 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
619 The parameters are expressions containing the following constants:
623 the computed values for @var{x} and @var{y}. They are evaluated for
627 the input width and height
630 same as @var{in_w} and @var{in_h}
633 the output (cropped) width and height
636 same as @var{out_w} and @var{out_h}
639 same as @var{iw} / @var{ih}
642 input sample aspect ratio
645 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
648 horizontal and vertical chroma subsample values. For example for the
649 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
652 the number of input frame, starting from 0
655 the position in the file of the input frame, NAN if unknown
658 timestamp expressed in seconds, NAN if the input timestamp is unknown
662 The @var{out_w} and @var{out_h} parameters specify the expressions for
663 the width and height of the output (cropped) video. They are
664 evaluated just at the configuration of the filter.
666 The default value of @var{out_w} is "in_w", and the default value of
667 @var{out_h} is "in_h".
669 The expression for @var{out_w} may depend on the value of @var{out_h},
670 and the expression for @var{out_h} may depend on @var{out_w}, but they
671 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
672 evaluated after @var{out_w} and @var{out_h}.
674 The @var{x} and @var{y} parameters specify the expressions for the
675 position of the top-left corner of the output (non-cropped) area. They
676 are evaluated for each frame. If the evaluated value is not valid, it
677 is approximated to the nearest valid value.
679 The default value of @var{x} is "(in_w-out_w)/2", and the default
680 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
681 the center of the input image.
683 The expression for @var{x} may depend on @var{y}, and the expression
684 for @var{y} may depend on @var{x}.
686 Follow some examples:
688 # crop the central input area with size 100x100
691 # crop the central input area with size 2/3 of the input video
692 "crop=2/3*in_w:2/3*in_h"
694 # crop the input video central square
697 # delimit the rectangle with the top-left corner placed at position
698 # 100:100 and the right-bottom corner corresponding to the right-bottom
699 # corner of the input image.
700 crop=in_w-100:in_h-100:100:100
702 # crop 10 pixels from the left and right borders, and 20 pixels from
703 # the top and bottom borders
704 "crop=in_w-2*10:in_h-2*20"
706 # keep only the bottom right quarter of the input image
707 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
709 # crop height for getting Greek harmony
710 "crop=in_w:1/PHI*in_w"
713 "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)"
715 # erratic camera effect depending on timestamp
716 "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)"
718 # set x depending on the value of y
719 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
724 Auto-detect crop size.
726 Calculate necessary cropping parameters and prints the recommended
727 parameters through the logging system. The detected dimensions
728 correspond to the non-black area of the input video.
730 It accepts the syntax:
732 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
738 Threshold, which can be optionally specified from nothing (0) to
739 everything (255), defaults to 24.
742 Value which the width/height should be divisible by, defaults to
743 16. The offset is automatically adjusted to center the video. Use 2 to
744 get only even dimensions (needed for 4:2:2 video). 16 is best when
745 encoding to most video codecs.
748 Counter that determines after how many frames cropdetect will reset
749 the previously detected largest video area and start over to detect
750 the current optimal crop area. Defaults to 0.
752 This can be useful when channel logos distort the video area. 0
753 indicates never reset and return the largest area encountered during
759 Suppress a TV station logo by a simple interpolation of the surrounding
760 pixels. Just set a rectangle covering the logo and watch it disappear
761 (and sometimes something even uglier appear - your mileage may vary).
763 The filter accepts parameters as a string of the form
764 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
765 @var{key}=@var{value} pairs, separated by ":".
767 The description of the accepted parameters follows.
772 Specify the top left corner coordinates of the logo. They must be
776 Specify the width and height of the logo to clear. They must be
780 Specify the thickness of the fuzzy edge of the rectangle (added to
781 @var{w} and @var{h}). The default value is 4.
784 When set to 1, a green rectangle is drawn on the screen to simplify
785 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
786 @var{band} is set to 4. The default value is 0.
790 Some examples follow.
795 Set a rectangle covering the area with top left corner coordinates 0,0
796 and size 100x77, setting a band of size 10:
802 As the previous example, but use named options:
804 delogo=x=0:y=0:w=100:h=77:band=10
811 Attempt to fix small changes in horizontal and/or vertical shift. This
812 filter helps remove camera shake from hand-holding a camera, bumping a
813 tripod, moving on a vehicle, etc.
815 The filter accepts parameters as a string of the form
816 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
818 A description of the accepted parameters follows.
823 Specify a rectangular area where to limit the search for motion
825 If desired the search for motion vectors can be limited to a
826 rectangular area of the frame defined by its top left corner, width
827 and height. These parameters have the same meaning as the drawbox
828 filter which can be used to visualise the position of the bounding
831 This is useful when simultaneous movement of subjects within the frame
832 might be confused for camera motion by the motion vector search.
834 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
835 then the full frame is used. This allows later options to be set
836 without specifying the bounding box for the motion vector search.
838 Default - search the whole frame.
841 Specify the maximum extent of movement in x and y directions in the
842 range 0-64 pixels. Default 16.
845 Specify how to generate pixels to fill blanks at the edge of the
846 frame. An integer from 0 to 3 as follows:
849 Fill zeroes at blank locations
851 Original image at blank locations
853 Extruded edge value at blank locations
855 Mirrored edge at blank locations
858 The default setting is mirror edge at blank locations.
861 Specify the blocksize to use for motion search. Range 4-128 pixels,
865 Specify the contrast threshold for blocks. Only blocks with more than
866 the specified contrast (difference between darkest and lightest
867 pixels) will be considered. Range 1-255, default 125.
870 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
871 search. Default - exhaustive search.
874 If set then a detailed log of the motion search is written to the
881 Draw a colored box on the input image.
883 It accepts the syntax:
885 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
891 Specify the top left corner coordinates of the box. Default to 0.
894 Specify the width and height of the box, if 0 they are interpreted as
895 the input width and height. Default to 0.
898 Specify the color of the box to write, it can be the name of a color
899 (case insensitive match) or a 0xRRGGBB[AA] sequence.
902 Follow some examples:
904 # draw a black box around the edge of the input image
907 # draw a box with color red and an opacity of 50%
908 drawbox=10:20:200:60:red@@0.5"
913 Draw text string or text from specified file on top of video using the
916 To enable compilation of this filter you need to configure FFmpeg with
917 @code{--enable-libfreetype}.
919 The filter also recognizes strftime() sequences in the provided text
920 and expands them accordingly. Check the documentation of strftime().
922 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
925 The description of the accepted parameters follows.
930 The font file to be used for drawing text. Path must be included.
931 This parameter is mandatory.
934 The text string to be drawn. The text must be a sequence of UTF-8
936 This parameter is mandatory if no file is specified with the parameter
940 A text file containing text to be drawn. The text must be a sequence
941 of UTF-8 encoded characters.
943 This parameter is mandatory if no text string is specified with the
944 parameter @var{text}.
946 If both text and textfile are specified, an error is thrown.
949 The expressions which specify the offsets where text will be drawn
950 within the video frame. They are relative to the top/left border of the
953 The default value of @var{x} and @var{y} is "0".
955 See below for the list of accepted constants.
958 The font size to be used for drawing text.
959 The default value of @var{fontsize} is 16.
962 The color to be used for drawing fonts.
963 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
964 (e.g. "0xff000033"), possibly followed by an alpha specifier.
965 The default value of @var{fontcolor} is "black".
968 The color to be used for drawing box around text.
969 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
970 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
971 The default value of @var{boxcolor} is "white".
974 Used to draw a box around text using background color.
975 Value should be either 1 (enable) or 0 (disable).
976 The default value of @var{box} is 0.
978 @item shadowx, shadowy
979 The x and y offsets for the text shadow position with respect to the
980 position of the text. They can be either positive or negative
981 values. Default value for both is "0".
984 The color to be used for drawing a shadow behind the drawn text. It
985 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
986 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
987 The default value of @var{shadowcolor} is "black".
990 Flags to be used for loading the fonts.
992 The flags map the corresponding flags supported by libfreetype, and are
993 a combination of the following values:
1000 @item vertical_layout
1001 @item force_autohint
1004 @item ignore_global_advance_width
1006 @item ignore_transform
1013 Default value is "render".
1015 For more information consult the documentation for the FT_LOAD_*
1019 The size in number of spaces to use for rendering the tab.
1023 The parameters for @var{x} and @var{y} are expressions containing the
1024 following constants:
1028 the input width and heigth
1031 the width of the rendered text
1034 the height of the rendered text
1037 the height of each text line
1040 input sample aspect ratio
1043 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
1046 horizontal and vertical chroma subsample values. For example for the
1047 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1050 maximum glyph width, that is the maximum width for all the glyphs
1051 contained in the rendered text
1054 maximum glyph height, that is the maximum height for all the glyphs
1055 contained in the rendered text, it is equivalent to @var{ascent} -
1058 @item max_glyph_a, ascent
1060 the maximum distance from the baseline to the highest/upper grid
1061 coordinate used to place a glyph outline point, for all the rendered
1063 It is a positive value, due to the grid's orientation with the Y axis
1066 @item max_glyph_d, descent
1067 the maximum distance from the baseline to the lowest grid coordinate
1068 used to place a glyph outline point, for all the rendered glyphs.
1069 This is a negative value, due to the grid's orientation, with the Y axis
1073 the number of input frame, starting from 0
1076 timestamp expressed in seconds, NAN if the input timestamp is unknown
1079 Some examples follow.
1084 Draw "Test Text" with font FreeSerif, using the default values for the
1085 optional parameters.
1088 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1092 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
1093 and y=50 (counting from the top-left corner of the screen), text is
1094 yellow with a red box around it. Both the text and the box have an
1098 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1099 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1102 Note that the double quotes are not necessary if spaces are not used
1103 within the parameter list.
1106 Show the text at the center of the video frame:
1108 drawtext=fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
1112 Show a text line sliding from right to left in the last row of the video
1113 frame. The file @file{LONG_LINE} is assumed to contain a single line
1116 drawtext=fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t
1120 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
1122 drawtext=fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
1126 Draw a single green letter "g", at the center of the input video.
1127 The glyph baseline is placed at half screen height.
1129 drawtext=fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent
1134 For more information about libfreetype, check:
1135 @url{http://www.freetype.org/}.
1139 Apply fade-in/out effect to input video.
1141 It accepts the parameters:
1142 @var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}]
1144 @var{type} specifies if the effect type, can be either "in" for
1145 fade-in, or "out" for a fade-out effect.
1147 @var{start_frame} specifies the number of the start frame for starting
1148 to apply the fade effect.
1150 @var{nb_frames} specifies the number of frames for which the fade
1151 effect has to last. At the end of the fade-in effect the output video
1152 will have the same intensity as the input video, at the end of the
1153 fade-out transition the output video will be completely black.
1155 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1156 separated by ":". The description of the accepted options follows.
1163 @item start_frame, s
1164 See @var{start_frame}.
1167 See @var{nb_frames}.
1171 A few usage examples follow, usable too as test scenarios.
1173 # fade in first 30 frames of video
1176 # fade out last 45 frames of a 200-frame video
1179 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
1180 fade=in:0:25, fade=out:975:25
1182 # make first 5 frames black, then fade in from frame 5-24
1188 Transform the field order of the input video.
1190 It accepts one parameter which specifies the required field order that
1191 the input interlaced video will be transformed to. The parameter can
1192 assume one of the following values:
1196 output bottom field first
1198 output top field first
1201 Default value is "tff".
1203 Transformation is achieved by shifting the picture content up or down
1204 by one line, and filling the remaining line with appropriate picture content.
1205 This method is consistent with most broadcast field order converters.
1207 If the input video is not flagged as being interlaced, or it is already
1208 flagged as being of the required output field order then this filter does
1209 not alter the incoming video.
1211 This filter is very useful when converting to or from PAL DV material,
1212 which is bottom field first.
1216 ./ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
1221 Buffer input images and send them when they are requested.
1223 This filter is mainly useful when auto-inserted by the libavfilter
1226 The filter does not take parameters.
1230 Convert the input video to one of the specified pixel formats.
1231 Libavfilter will try to pick one that is supported for the input to
1234 The filter accepts a list of pixel format names, separated by ":",
1235 for example "yuv420p:monow:rgb24".
1237 Some examples follow:
1239 # convert the input video to the format "yuv420p"
1242 # convert the input video to any of the formats in the list
1243 format=yuv420p:yuv444p:yuv410p
1249 Apply a frei0r effect to the input video.
1251 To enable compilation of this filter you need to install the frei0r
1252 header and configure FFmpeg with --enable-frei0r.
1254 The filter supports the syntax:
1256 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
1259 @var{filter_name} is the name to the frei0r effect to load. If the
1260 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
1261 is searched in each one of the directories specified by the colon
1262 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
1263 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
1264 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
1266 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
1267 for the frei0r effect.
1269 A frei0r effect parameter can be a boolean (whose values are specified
1270 with "y" and "n"), a double, a color (specified by the syntax
1271 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1272 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1273 description), a position (specified by the syntax @var{X}/@var{Y},
1274 @var{X} and @var{Y} being float numbers) and a string.
1276 The number and kind of parameters depend on the loaded effect. If an
1277 effect parameter is not specified the default value is set.
1279 Some examples follow:
1281 # apply the distort0r effect, set the first two double parameters
1282 frei0r=distort0r:0.5:0.01
1284 # apply the colordistance effect, takes a color as first parameter
1285 frei0r=colordistance:0.2/0.3/0.4
1286 frei0r=colordistance:violet
1287 frei0r=colordistance:0x112233
1289 # apply the perspective effect, specify the top left and top right
1291 frei0r=perspective:0.2/0.2:0.8/0.2
1294 For more information see:
1295 @url{http://piksel.org/frei0r}
1299 Fix the banding artifacts that are sometimes introduced into nearly flat
1300 regions by truncation to 8bit colordepth.
1301 Interpolate the gradients that should go where the bands are, and
1304 This filter is designed for playback only. Do not use it prior to
1305 lossy compression, because compression tends to lose the dither and
1306 bring back the bands.
1308 The filter takes two optional parameters, separated by ':':
1309 @var{strength}:@var{radius}
1311 @var{strength} is the maximum amount by which the filter will change
1312 any one pixel. Also the threshold for detecting nearly flat
1313 regions. Acceptable values range from .51 to 255, default value is
1314 1.2, out-of-range values will be clipped to the valid range.
1316 @var{radius} is the neighborhood to fit the gradient to. A larger
1317 radius makes for smoother gradients, but also prevents the filter from
1318 modifying the pixels near detailed regions. Acceptable values are
1319 8-32, default value is 16, out-of-range values will be clipped to the
1323 # default parameters
1332 Flip the input video horizontally.
1334 For example to horizontally flip the video in input with
1337 ffmpeg -i in.avi -vf "hflip" out.avi
1342 High precision/quality 3d denoise filter. This filter aims to reduce
1343 image noise producing smooth images and making still images really
1344 still. It should enhance compressibility.
1346 It accepts the following optional parameters:
1347 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
1351 a non-negative float number which specifies spatial luma strength,
1354 @item chroma_spatial
1355 a non-negative float number which specifies spatial chroma strength,
1356 defaults to 3.0*@var{luma_spatial}/4.0
1359 a float number which specifies luma temporal strength, defaults to
1360 6.0*@var{luma_spatial}/4.0
1363 a float number which specifies chroma temporal strength, defaults to
1364 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1367 @section lut, lutrgb, lutyuv
1369 Compute a look-up table for binding each pixel component input value
1370 to an output value, and apply it to input video.
1372 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1373 to an RGB input video.
1375 These filters accept in input a ":"-separated list of options, which
1376 specify the expressions used for computing the lookup table for the
1377 corresponding pixel component values.
1379 The @var{lut} filter requires either YUV or RGB pixel formats in
1380 input, and accepts the options:
1383 first pixel component
1385 second pixel component
1387 third pixel component
1389 fourth pixel component, corresponds to the alpha component
1392 The exact component associated to each option depends on the format in
1395 The @var{lutrgb} filter requires RGB pixel formats in input, and
1396 accepts the options:
1408 The @var{lutyuv} filter requires YUV pixel formats in input, and
1409 accepts the options:
1412 Y/luminance component
1421 The expressions can contain the following constants and functions:
1425 the input width and heigth
1428 input value for the pixel component
1431 the input value clipped in the @var{minval}-@var{maxval} range
1434 maximum value for the pixel component
1437 minimum value for the pixel component
1440 the negated value for the pixel component value clipped in the
1441 @var{minval}-@var{maxval} range , it corresponds to the expression
1442 "maxval-clipval+minval"
1445 the computed value in @var{val} clipped in the
1446 @var{minval}-@var{maxval} range
1448 @item gammaval(gamma)
1449 the computed gamma correction value of the pixel component value
1450 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1452 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1456 All expressions default to "val".
1458 Some examples follow:
1460 # negate input video
1461 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1462 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1464 # the above is the same as
1465 lutrgb="r=negval:g=negval:b=negval"
1466 lutyuv="y=negval:u=negval:v=negval"
1471 # remove chroma components, turns the video into a graytone image
1472 lutyuv="u=128:v=128"
1474 # apply a luma burning effect
1477 # remove green and blue components
1480 # set a constant alpha channel value on input
1481 format=rgba,lutrgb=a="maxval-minval/2"
1483 # correct luminance gamma by a 0.5 factor
1484 lutyuv=y=gammaval(0.5)
1489 Apply an MPlayer filter to the input video.
1491 This filter provides a wrapper around most of the filters of
1494 This wrapper is considered experimental. Some of the wrapped filters
1495 may not work properly and we may drop support for them, as they will
1496 be implemented natively into FFmpeg. Thus you should avoid
1497 depending on them when writing portable scripts.
1499 The filters accepts the parameters:
1500 @var{filter_name}[:=]@var{filter_params}
1502 @var{filter_name} is the name of a supported MPlayer filter,
1503 @var{filter_params} is a string containing the parameters accepted by
1506 The list of the currently supported filters follows:
1560 The parameter syntax and behavior for the listed filters are the same
1561 of the corresponding MPlayer filters. For detailed instructions check
1562 the "VIDEO FILTERS" section in the MPlayer manual.
1564 Some examples follow:
1566 # remove a logo by interpolating the surrounding pixels
1567 mp=delogo=200:200:80:20:1
1569 # adjust gamma, brightness, contrast
1572 # tweak hue and saturation
1576 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
1582 This filter accepts an integer in input, if non-zero it negates the
1583 alpha component (if available). The default value in input is 0.
1587 Force libavfilter not to use any of the specified pixel formats for the
1588 input to the next filter.
1590 The filter accepts a list of pixel format names, separated by ":",
1591 for example "yuv420p:monow:rgb24".
1593 Some examples follow:
1595 # force libavfilter to use a format different from "yuv420p" for the
1596 # input to the vflip filter
1597 noformat=yuv420p,vflip
1599 # convert the input video to any of the formats not contained in the list
1600 noformat=yuv420p:yuv444p:yuv410p
1605 Pass the video source unchanged to the output.
1609 Apply video transform using libopencv.
1611 To enable this filter install libopencv library and headers and
1612 configure FFmpeg with --enable-libopencv.
1614 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1616 @var{filter_name} is the name of the libopencv filter to apply.
1618 @var{filter_params} specifies the parameters to pass to the libopencv
1619 filter. If not specified the default values are assumed.
1621 Refer to the official libopencv documentation for more precise
1623 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1625 Follows the list of supported libopencv filters.
1630 Dilate an image by using a specific structuring element.
1631 This filter corresponds to the libopencv function @code{cvDilate}.
1633 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1635 @var{struct_el} represents a structuring element, and has the syntax:
1636 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1638 @var{cols} and @var{rows} represent the number of colums and rows of
1639 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1640 point, and @var{shape} the shape for the structuring element, and
1641 can be one of the values "rect", "cross", "ellipse", "custom".
1643 If the value for @var{shape} is "custom", it must be followed by a
1644 string of the form "=@var{filename}". The file with name
1645 @var{filename} is assumed to represent a binary image, with each
1646 printable character corresponding to a bright pixel. When a custom
1647 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1648 or columns and rows of the read file are assumed instead.
1650 The default value for @var{struct_el} is "3x3+0x0/rect".
1652 @var{nb_iterations} specifies the number of times the transform is
1653 applied to the image, and defaults to 1.
1655 Follow some example:
1657 # use the default values
1660 # dilate using a structuring element with a 5x5 cross, iterate two times
1661 ocv=dilate=5x5+2x2/cross:2
1663 # read the shape from the file diamond.shape, iterate two times
1664 # the file diamond.shape may contain a pattern of characters like this:
1670 # the specified cols and rows are ignored (but not the anchor point coordinates)
1671 ocv=0x0+2x2/custom=diamond.shape:2
1676 Erode an image by using a specific structuring element.
1677 This filter corresponds to the libopencv function @code{cvErode}.
1679 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1680 with the same syntax and semantics as the @ref{dilate} filter.
1684 Smooth the input video.
1686 The filter takes the following parameters:
1687 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1689 @var{type} is the type of smooth filter to apply, and can be one of
1690 the following values: "blur", "blur_no_scale", "median", "gaussian",
1691 "bilateral". The default value is "gaussian".
1693 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1694 parameters whose meanings depend on smooth type. @var{param1} and
1695 @var{param2} accept integer positive values or 0, @var{param3} and
1696 @var{param4} accept float values.
1698 The default value for @var{param1} is 3, the default value for the
1699 other parameters is 0.
1701 These parameters correspond to the parameters assigned to the
1702 libopencv function @code{cvSmooth}.
1706 Overlay one video on top of another.
1708 It takes two inputs and one output, the first input is the "main"
1709 video on which the second input is overlayed.
1711 It accepts the parameters: @var{x}:@var{y}[:@var{options}].
1713 @var{x} is the x coordinate of the overlayed video on the main video,
1714 @var{y} is the y coordinate. @var{x} and @var{y} are expressions containing
1715 the following parameters:
1718 @item main_w, main_h
1719 main input width and height
1722 same as @var{main_w} and @var{main_h}
1724 @item overlay_w, overlay_h
1725 overlay input width and height
1728 same as @var{overlay_w} and @var{overlay_h}
1731 @var{options} is an optional list of @var{key}=@var{value} pairs,
1734 The description of the accepted options follows.
1738 If set to 1, force the filter to accept inputs in the RGB
1739 colorspace. Default value is 0.
1742 Be aware that frames are taken from each input video in timestamp
1743 order, hence, if their initial timestamps differ, it is a a good idea
1744 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1745 have them begin in the same zero timestamp, as it does the example for
1746 the @var{movie} filter.
1748 Follow some examples:
1750 # draw the overlay at 10 pixels from the bottom right
1751 # corner of the main video.
1752 overlay=main_w-overlay_w-10:main_h-overlay_h-10
1754 # insert a transparent PNG logo in the bottom left corner of the input
1755 movie=logo.png [logo];
1756 [in][logo] overlay=10:main_h-overlay_h-10 [out]
1758 # insert 2 different transparent PNG logos (second logo on bottom
1760 movie=logo1.png [logo1];
1761 movie=logo2.png [logo2];
1762 [in][logo1] overlay=10:H-h-10 [in+logo1];
1763 [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
1765 # add a transparent color layer on top of the main video,
1766 # WxH specifies the size of the main input to the overlay filter
1767 color=red@.3:WxH [over]; [in][over] overlay [out]
1770 You can chain together more overlays but the efficiency of such
1771 approach is yet to be tested.
1775 Add paddings to the input image, and places the original input at the
1776 given coordinates @var{x}, @var{y}.
1778 It accepts the following parameters:
1779 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1781 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1782 expressions containing the following constants:
1786 the input video width and height
1789 same as @var{in_w} and @var{in_h}
1792 the output width and height, that is the size of the padded area as
1793 specified by the @var{width} and @var{height} expressions
1796 same as @var{out_w} and @var{out_h}
1799 x and y offsets as specified by the @var{x} and @var{y}
1800 expressions, or NAN if not yet specified
1803 same as @var{iw} / @var{ih}
1806 input sample aspect ratio
1809 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1812 horizontal and vertical chroma subsample values. For example for the
1813 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1816 Follows the description of the accepted parameters.
1821 Specify the size of the output image with the paddings added. If the
1822 value for @var{width} or @var{height} is 0, the corresponding input size
1823 is used for the output.
1825 The @var{width} expression can reference the value set by the
1826 @var{height} expression, and viceversa.
1828 The default value of @var{width} and @var{height} is 0.
1832 Specify the offsets where to place the input image in the padded area
1833 with respect to the top/left border of the output image.
1835 The @var{x} expression can reference the value set by the @var{y}
1836 expression, and viceversa.
1838 The default value of @var{x} and @var{y} is 0.
1842 Specify the color of the padded area, it can be the name of a color
1843 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1845 The default value of @var{color} is "black".
1849 Some examples follow:
1852 # Add paddings with color "violet" to the input video. Output video
1853 # size is 640x480, the top-left corner of the input video is placed at
1855 pad=640:480:0:40:violet
1857 # pad the input to get an output with dimensions increased bt 3/2,
1858 # and put the input video at the center of the padded area
1859 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1861 # pad the input to get a squared output with size equal to the maximum
1862 # value between the input width and height, and put the input video at
1863 # the center of the padded area
1864 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1866 # pad the input to get a final w/h ratio of 16:9
1867 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1869 # for anamorphic video, in order to set the output display aspect ratio,
1870 # it is necessary to use sar in the expression, according to the relation:
1871 # (ih * X / ih) * sar = output_dar
1872 # X = output_dar / sar
1873 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
1875 # double output size and put the input video in the bottom-right
1876 # corner of the output padded area
1877 pad="2*iw:2*ih:ow-iw:oh-ih"
1880 @section pixdesctest
1882 Pixel format descriptor test filter, mainly useful for internal
1883 testing. The output video should be equal to the input video.
1887 format=monow, pixdesctest
1890 can be used to test the monowhite pixel format descriptor definition.
1894 Scale the input video to @var{width}:@var{height}[:@var{interl}=@{1|-1@}] and/or convert the image format.
1896 The parameters @var{width} and @var{height} are expressions containing
1897 the following constants:
1901 the input width and height
1904 same as @var{in_w} and @var{in_h}
1907 the output (cropped) width and height
1910 same as @var{out_w} and @var{out_h}
1913 same as @var{iw} / @var{ih}
1916 input sample aspect ratio
1919 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1922 input sample aspect ratio
1925 horizontal and vertical chroma subsample values. For example for the
1926 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1929 If the input image format is different from the format requested by
1930 the next filter, the scale filter will convert the input to the
1933 If the value for @var{width} or @var{height} is 0, the respective input
1934 size is used for the output.
1936 If the value for @var{width} or @var{height} is -1, the scale filter will
1937 use, for the respective output size, a value that maintains the aspect
1938 ratio of the input image.
1940 The default value of @var{width} and @var{height} is 0.
1942 Valid values for the optional parameter @var{interl} are:
1946 force interlaced aware scaling
1949 select interlaced aware scaling depending on whether the source frames
1950 are flagged as interlaced or not
1953 Some examples follow:
1955 # scale the input video to a size of 200x100.
1958 # scale the input to 2x
1960 # the above is the same as
1963 # scale the input to half size
1966 # increase the width, and set the height to the same size
1969 # seek for Greek harmony
1973 # increase the height, and set the width to 3/2 of the height
1976 # increase the size, but make the size a multiple of the chroma
1977 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1979 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1980 scale='min(500\, iw*3/2):-1'
1984 Select frames to pass in output.
1986 It accepts in input an expression, which is evaluated for each input
1987 frame. If the expression is evaluated to a non-zero value, the frame
1988 is selected and passed to the output, otherwise it is discarded.
1990 The expression can contain the following constants:
1994 the sequential number of the filtered frame, starting from 0
1997 the sequential number of the selected frame, starting from 0
1999 @item prev_selected_n
2000 the sequential number of the last selected frame, NAN if undefined
2003 timebase of the input timestamps
2006 the PTS (Presentation TimeStamp) of the filtered video frame,
2007 expressed in @var{TB} units, NAN if undefined
2010 the PTS (Presentation TimeStamp) of the filtered video frame,
2011 expressed in seconds, NAN if undefined
2014 the PTS of the previously filtered video frame, NAN if undefined
2016 @item prev_selected_pts
2017 the PTS of the last previously filtered video frame, NAN if undefined
2019 @item prev_selected_t
2020 the PTS of the last previously selected video frame, NAN if undefined
2023 the PTS of the first video frame in the video, NAN if undefined
2026 the time of the first video frame in the video, NAN if undefined
2029 the type of the filtered frame, can assume one of the following
2041 @item interlace_type
2042 the frame interlace type, can assume one of the following values:
2045 the frame is progressive (not interlaced)
2047 the frame is top-field-first
2049 the frame is bottom-field-first
2053 1 if the filtered frame is a key-frame, 0 otherwise
2056 the position in the file of the filtered frame, -1 if the information
2057 is not available (e.g. for synthetic video)
2060 The default value of the select expression is "1".
2062 Some examples follow:
2065 # select all frames in input
2068 # the above is the same as:
2074 # select only I-frames
2075 select='eq(pict_type\,I)'
2077 # select one frame every 100
2078 select='not(mod(n\,100))'
2080 # select only frames contained in the 10-20 time interval
2081 select='gte(t\,10)*lte(t\,20)'
2083 # select only I frames contained in the 10-20 time interval
2084 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2086 # select frames with a minimum distance of 10 seconds
2087 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2093 Set the Display Aspect Ratio for the filter output video.
2095 This is done by changing the specified Sample (aka Pixel) Aspect
2096 Ratio, according to the following equation:
2097 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2099 Keep in mind that this filter does not modify the pixel dimensions of
2100 the video frame. Also the display aspect ratio set by this filter may
2101 be changed by later filters in the filterchain, e.g. in case of
2102 scaling or if another "setdar" or a "setsar" filter is applied.
2104 The filter accepts a parameter string which represents the wanted
2105 display aspect ratio.
2106 The parameter can be a floating point number string, or an expression
2107 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
2108 numerator and denominator of the aspect ratio.
2109 If the parameter is not specified, it is assumed the value "0:1".
2111 For example to change the display aspect ratio to 16:9, specify:
2114 # the above is equivalent to
2118 See also the @ref{setsar} filter documentation.
2122 Change the PTS (presentation timestamp) of the input video frames.
2124 Accept in input an expression evaluated through the eval API, which
2125 can contain the following constants:
2129 the presentation timestamp in input
2132 the count of the input frame, starting from 0.
2135 the PTS of the first video frame
2138 tell if the current frame is interlaced
2141 original position in the file of the frame, or undefined if undefined
2142 for the current frame
2152 Some examples follow:
2155 # start counting PTS from zero
2167 # fixed rate 25 fps with some jitter
2168 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
2174 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
2176 Note that as a consequence of the application of this filter, the
2177 output display aspect ratio will change according to the following
2179 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2181 Keep in mind that the sample aspect ratio set by this filter may be
2182 changed by later filters in the filterchain, e.g. if another "setsar"
2183 or a "setdar" filter is applied.
2185 The filter accepts a parameter string which represents the wanted
2186 sample aspect ratio.
2187 The parameter can be a floating point number string, or an expression
2188 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
2189 numerator and denominator of the aspect ratio.
2190 If the parameter is not specified, it is assumed the value "0:1".
2192 For example to change the sample aspect ratio to 10:11, specify:
2199 Set the timebase to use for the output frames timestamps.
2200 It is mainly useful for testing timebase configuration.
2202 It accepts in input an arithmetic expression representing a rational.
2203 The expression can contain the constants "AVTB" (the
2204 default timebase), and "intb" (the input timebase).
2206 The default value for the input is "intb".
2208 Follow some examples.
2211 # set the timebase to 1/25
2214 # set the timebase to 1/10
2217 #set the timebase to 1001/1000
2220 #set the timebase to 2*intb
2223 #set the default timebase value
2229 Show a line containing various information for each input video frame.
2230 The input video is not modified.
2232 The shown line contains a sequence of key/value pairs of the form
2233 @var{key}:@var{value}.
2235 A description of each shown parameter follows:
2239 sequential number of the input frame, starting from 0
2242 Presentation TimeStamp of the input frame, expressed as a number of
2243 time base units. The time base unit depends on the filter input pad.
2246 Presentation TimeStamp of the input frame, expressed as a number of
2250 position of the frame in the input stream, -1 if this information in
2251 unavailable and/or meanigless (for example in case of synthetic video)
2257 sample aspect ratio of the input frame, expressed in the form
2261 size of the input frame, expressed in the form
2262 @var{width}x@var{height}
2265 interlaced mode ("P" for "progressive", "T" for top field first, "B"
2266 for bottom field first)
2269 1 if the frame is a key frame, 0 otherwise
2272 picture type of the input frame ("I" for an I-frame, "P" for a
2273 P-frame, "B" for a B-frame, "?" for unknown type).
2274 Check also the documentation of the @code{AVPictureType} enum and of
2275 the @code{av_get_picture_type_char} function defined in
2276 @file{libavutil/avutil.h}.
2279 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
2281 @item plane_checksum
2282 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
2283 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
2288 Pass the images of input video on to next video filter as multiple
2292 ./ffmpeg -i in.avi -vf "slicify=32" out.avi
2295 The filter accepts the slice height as parameter. If the parameter is
2296 not specified it will use the default value of 16.
2298 Adding this in the beginning of filter chains should make filtering
2299 faster due to better use of the memory cache.
2303 Pass on the input video to two outputs. Both outputs are identical to
2308 [in] split [splitout1][splitout2];
2309 [splitout1] crop=100:100:0:0 [cropout];
2310 [splitout2] pad=200:200:100:100 [padout];
2313 will create two separate outputs from the same input, one cropped and
2318 Transpose rows with columns in the input video and optionally flip it.
2320 It accepts a parameter representing an integer, which can assume the
2325 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2333 Rotate by 90 degrees clockwise, that is:
2341 Rotate by 90 degrees counterclockwise, that is:
2349 Rotate by 90 degrees clockwise and vertically flip, that is:
2359 Sharpen or blur the input video.
2361 It accepts the following parameters:
2362 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
2364 Negative values for the amount will blur the input video, while positive
2365 values will sharpen. All parameters are optional and default to the
2366 equivalent of the string '5:5:1.0:5:5:0.0'.
2371 Set the luma matrix horizontal size. It can be an integer between 3
2372 and 13, default value is 5.
2375 Set the luma matrix vertical size. It can be an integer between 3
2376 and 13, default value is 5.
2379 Set the luma effect strength. It can be a float number between -2.0
2380 and 5.0, default value is 1.0.
2382 @item chroma_msize_x
2383 Set the chroma matrix horizontal size. It can be an integer between 3
2384 and 13, default value is 5.
2386 @item chroma_msize_y
2387 Set the chroma matrix vertical size. It can be an integer between 3
2388 and 13, default value is 5.
2391 Set the chroma effect strength. It can be a float number between -2.0
2392 and 5.0, default value is 0.0.
2397 # Strong luma sharpen effect parameters
2400 # Strong blur of both luma and chroma parameters
2401 unsharp=7:7:-2:7:7:-2
2403 # Use the default values with @command{ffmpeg}
2404 ./ffmpeg -i in.avi -vf "unsharp" out.mp4
2409 Flip the input video vertically.
2412 ./ffmpeg -i in.avi -vf "vflip" out.avi
2417 Deinterlace the input video ("yadif" means "yet another deinterlacing
2420 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
2422 @var{mode} specifies the interlacing mode to adopt, accepts one of the
2427 output 1 frame for each frame
2429 output 1 frame for each field
2431 like 0 but skips spatial interlacing check
2433 like 1 but skips spatial interlacing check
2438 @var{parity} specifies the picture field parity assumed for the input
2439 interlaced video, accepts one of the following values:
2443 assume top field first
2445 assume bottom field first
2447 enable automatic detection
2450 Default value is -1.
2451 If interlacing is unknown or decoder does not export this information,
2452 top field first will be assumed.
2454 @var{auto} specifies if deinterlacer should trust the interlaced flag
2455 and only deinterlace frames marked as interlaced
2459 deinterlace all frames
2461 only deinterlace frames marked as interlaced
2466 @c man end VIDEO FILTERS
2468 @chapter Video Sources
2469 @c man begin VIDEO SOURCES
2471 Below is a description of the currently available video sources.
2475 Buffer video frames, and make them available to the filter chain.
2477 This source is mainly intended for a programmatic use, in particular
2478 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2480 It accepts the following parameters:
2481 @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}
2483 All the parameters but @var{scale_params} need to be explicitly
2486 Follows the list of the accepted parameters.
2491 Specify the width and height of the buffered video frames.
2493 @item pix_fmt_string
2494 A string representing the pixel format of the buffered video frames.
2495 It may be a number corresponding to a pixel format, or a pixel format
2498 @item timebase_num, timebase_den
2499 Specify numerator and denomitor of the timebase assumed by the
2500 timestamps of the buffered frames.
2502 @item sample_aspect_ratio.num, sample_aspect_ratio.den
2503 Specify numerator and denominator of the sample aspect ratio assumed
2504 by the video frames.
2507 Specify the optional parameters to be used for the scale filter which
2508 is automatically inserted when an input change is detected in the
2509 input size or format.
2514 buffer=320:240:yuv410p:1:24:1:1
2517 will instruct the source to accept video frames with size 320x240 and
2518 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2519 square pixels (1:1 sample aspect ratio).
2520 Since the pixel format with name "yuv410p" corresponds to the number 6
2521 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
2522 this example corresponds to:
2524 buffer=320:240:6:1:24:1:1
2529 Provide an uniformly colored input.
2531 It accepts the following parameters:
2532 @var{color}:@var{frame_size}:@var{frame_rate}
2534 Follows the description of the accepted parameters.
2539 Specify the color of the source. It can be the name of a color (case
2540 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2541 alpha specifier. The default value is "black".
2544 Specify the size of the sourced video, it may be a string of the form
2545 @var{width}x@var{height}, or the name of a size abbreviation. The
2546 default value is "320x240".
2549 Specify the frame rate of the sourced video, as the number of frames
2550 generated per second. It has to be a string in the format
2551 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2552 number or a valid video frame rate abbreviation. The default value is
2557 For example the following graph description will generate a red source
2558 with an opacity of 0.2, with size "qcif" and a frame rate of 10
2559 frames per second, which will be overlayed over the source connected
2560 to the pad with identifier "in".
2563 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2568 Read a video stream from a movie container.
2570 It accepts the syntax: @var{movie_name}[:@var{options}] where
2571 @var{movie_name} is the name of the resource to read (not necessarily
2572 a file but also a device or a stream accessed through some protocol),
2573 and @var{options} is an optional sequence of @var{key}=@var{value}
2574 pairs, separated by ":".
2576 The description of the accepted options follows.
2580 @item format_name, f
2581 Specifies the format assumed for the movie to read, and can be either
2582 the name of a container or an input device. If not specified the
2583 format is guessed from @var{movie_name} or by probing.
2585 @item seek_point, sp
2586 Specifies the seek point in seconds, the frames will be output
2587 starting from this seek point, the parameter is evaluated with
2588 @code{av_strtod} so the numerical value may be suffixed by an IS
2589 postfix. Default value is "0".
2591 @item stream_index, si
2592 Specifies the index of the video stream to read. If the value is -1,
2593 the best suited video stream will be automatically selected. Default
2598 This filter allows to overlay a second video on top of main input of
2599 a filtergraph as shown in this graph:
2601 input -----------> deltapts0 --> overlay --> output
2604 movie --> scale--> deltapts1 -------+
2607 Some examples follow:
2609 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
2610 # on top of the input labelled as "in".
2611 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2612 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2614 # read from a video4linux2 device, and overlay it on top of the input
2616 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2617 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2623 Generate various test patterns, as generated by the MPlayer test filter.
2625 The size of the generated video is fixed, and is 256x256.
2626 This source is useful in particular for testing encoding features.
2628 This source accepts an optional sequence of @var{key}=@var{value} pairs,
2629 separated by ":". The description of the accepted options follows.
2634 Specify the frame rate of the sourced video, as the number of frames
2635 generated per second. It has to be a string in the format
2636 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2637 number or a valid video frame rate abbreviation. The default value is
2641 Set the video duration of the sourced video. The accepted syntax is:
2643 [-]HH[:MM[:SS[.m...]]]
2646 See also the function @code{av_parse_time()}.
2648 If not specified, or the expressed duration is negative, the video is
2649 supposed to be generated forever.
2653 Set the number or the name of the test to perform. Supported tests are:
2668 Default value is "all", which will cycle through the list of all tests.
2671 For example the following:
2676 will generate a "dc_luma" test pattern.
2680 Provide a frei0r source.
2682 To enable compilation of this filter you need to install the frei0r
2683 header and configure FFmpeg with --enable-frei0r.
2685 The source supports the syntax:
2687 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
2690 @var{size} is the size of the video to generate, may be a string of the
2691 form @var{width}x@var{height} or a frame size abbreviation.
2692 @var{rate} is the rate of the video to generate, may be a string of
2693 the form @var{num}/@var{den} or a frame rate abbreviation.
2694 @var{src_name} is the name to the frei0r source to load. For more
2695 information regarding frei0r and how to set the parameters read the
2696 section @ref{frei0r} in the description of the video filters.
2698 Some examples follow:
2700 # generate a frei0r partik0l source with size 200x200 and framerate 10
2701 # which is overlayed on the overlay filter main input
2702 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
2705 @section nullsrc, rgbtestsrc, testsrc
2707 The @code{nullsrc} source returns unprocessed video frames. It is
2708 mainly useful to be employed in analysis / debugging tools, or as the
2709 source for filters which ignore the input data.
2711 The @code{rgbtestsrc} source generates an RGB test pattern useful for
2712 detecting RGB vs BGR issues. You should see a red, green and blue
2713 stripe from top to bottom.
2715 The @code{testsrc} source generates a test video pattern, showing a
2716 color pattern, a scrolling gradient and a timestamp. This is mainly
2717 intended for testing purposes.
2719 These sources accept an optional sequence of @var{key}=@var{value} pairs,
2720 separated by ":". The description of the accepted options follows.
2725 Specify the size of the sourced video, it may be a string of the form
2726 @var{width}x@var{heigth}, or the name of a size abbreviation. The
2727 default value is "320x240".
2730 Specify the frame rate of the sourced video, as the number of frames
2731 generated per second. It has to be a string in the format
2732 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2733 number or a valid video frame rate abbreviation. The default value is
2737 Set the sample aspect ratio of the sourced video.
2740 Set the video duration of the sourced video. The accepted syntax is:
2742 [-]HH[:MM[:SS[.m...]]]
2745 See also the function @code{av_parse_time()}.
2747 If not specified, or the expressed duration is negative, the video is
2748 supposed to be generated forever.
2751 For example the following:
2753 testsrc=duration=5.3:size=qcif:rate=10
2756 will generate a video with a duration of 5.3 seconds, with size
2757 176x144 and a framerate of 10 frames per second.
2759 If the input content is to be ignored, @code{nullsrc} can be used. The
2760 following command generates noise in the luminance plane by employing
2761 the @code{mp=geq} filter:
2763 nullsrc=s=256x256, mp=geq=random(1)*255:128:128
2766 @c man end VIDEO SOURCES
2768 @chapter Video Sinks
2769 @c man begin VIDEO SINKS
2771 Below is a description of the currently available video sinks.
2775 Buffer video frames, and make them available to the end of the filter
2778 This sink is mainly intended for a programmatic use, in particular
2779 through the interface defined in @file{libavfilter/buffersink.h}.
2781 It does not require a string parameter in input, but you need to
2782 specify a pointer to a list of supported pixel formats terminated by
2783 -1 in the opaque parameter provided to @code{avfilter_init_filter}
2784 when initializing this sink.
2788 Null video sink, do absolutely nothing with the input video. It is
2789 mainly useful as a template and to be employed in analysis / debugging
2792 @c man end VIDEO SINKS