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 Mix channels with specific gain levels. The filter accepts the output
241 channel layout followed by a set of channels definitions.
243 The filter accepts parameters of the form:
244 "@var{l}:@var{outdef}:@var{outdef}:..."
248 output channel layout or number of channels
251 output channel specification, of the form:
252 "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]"
255 output channel to define, either a channel name (FL, FR, etc.) or a channel
256 number (c0, c1, etc.)
259 multiplicative coefficient for the channel, 1 leaving the volume unchanged
262 input channel to use, see out_name for details; it is not possible to mix
263 named and numbered input channels
266 If the `=' in a channel specification is replaced by `<', then the gains for
267 that specification will be renormalized so that the total is 1, thus
268 avoiding clipping noise.
270 For example, if you want to down-mix from stereo to mono, but with a bigger
271 factor for the left channel:
273 pan=1:c0=0.9*c0+0.1*c1
276 A customized down-mix to stereo that works automatically for 3-, 4-, 5- and
279 pan=stereo: FL < FL + 0.5*FC + 0.6*BL + 0.6*SL : FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
282 Note that @file{ffmpeg} integrates a default down-mix (and up-mix) system
283 that should be preferred (see "-ac" option) unless you have very specific
288 Adjust the input audio volume.
290 The filter accepts exactly one parameter @var{vol}, which expresses
291 how the audio volume will be increased or decreased.
293 Output values are clipped to the maximum value.
295 If @var{vol} is expressed as a decimal number, and the output audio
296 volume is given by the relation:
298 @var{output_volume} = @var{vol} * @var{input_volume}
301 If @var{vol} is expressed as a decimal number followed by the string
302 "dB", the value represents the requested change in decibels of the
303 input audio power, and the output audio volume is given by the
306 @var{output_volume} = 10^(@var{vol}/20) * @var{input_volume}
309 Otherwise @var{vol} is considered an expression and its evaluated
310 value is used for computing the output audio volume according to the
313 Default value for @var{vol} is 1.0.
319 Half the input audio volume:
324 The above example is equivalent to:
330 Decrease input audio power by 12 decibels:
336 @c man end AUDIO FILTERS
338 @chapter Audio Sources
339 @c man begin AUDIO SOURCES
341 Below is a description of the currently available audio sources.
345 Buffer audio frames, and make them available to the filter chain.
347 This source is mainly intended for a programmatic use, in particular
348 through the interface defined in @file{libavfilter/asrc_abuffer.h}.
350 It accepts the following mandatory parameters:
351 @var{sample_rate}:@var{sample_fmt}:@var{channel_layout}:@var{packing}
356 The sample rate of the incoming audio buffers.
359 The sample format of the incoming audio buffers.
360 Either a sample format name or its corresponging integer representation from
361 the enum AVSampleFormat in @file{libavutil/samplefmt.h}
364 The channel layout of the incoming audio buffers.
365 Either a channel layout name from channel_layout_map in
366 @file{libavutil/audioconvert.c} or its corresponding integer representation
367 from the AV_CH_LAYOUT_* macros in @file{libavutil/audioconvert.h}
370 Either "packed" or "planar", or their integer representation: 0 or 1
377 abuffer=44100:s16:stereo:planar
380 will instruct the source to accept planar 16bit signed stereo at 44100Hz.
381 Since the sample format with name "s16" corresponds to the number
382 1 and the "stereo" channel layout corresponds to the value 3, this is
390 Generate an audio signal specified by an expression.
392 This source accepts in input one or more expressions (one for each
393 channel), which are evaluated and used to generate a corresponding
396 It accepts the syntax: @var{exprs}[::@var{options}].
397 @var{exprs} is a list of expressions separated by ":", one for each
398 separate channel. The output channel layout depends on the number of
399 provided expressions, up to 8 channels are supported.
401 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
404 The description of the accepted options follows.
409 Set the number of samples per channel per each output frame,
413 Specify the sample rate, default to 44100.
416 Each expression in @var{exprs} can contain the following constants:
420 number of the evaluated sample, starting from 0
423 time of the evaluated sample expressed in seconds, starting from 0
442 Generate a sin signal with frequence of 440 Hz, set sample rate to
445 aevalsrc="sin(440*2*PI*t)::s=8000"
449 Generate white noise:
451 aevalsrc="-2+random(0)"
455 Generate an amplitude modulated signal:
457 aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
461 Generate 2.5 Hz binaural beats on a 360 Hz carrier:
463 aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) : 0.1*sin(2*PI*(360+2.5/2)*t)"
470 Read an audio stream from a movie container.
472 It accepts the syntax: @var{movie_name}[:@var{options}] where
473 @var{movie_name} is the name of the resource to read (not necessarily
474 a file but also a device or a stream accessed through some protocol),
475 and @var{options} is an optional sequence of @var{key}=@var{value}
476 pairs, separated by ":".
478 The description of the accepted options follows.
483 Specify the format assumed for the movie to read, and can be either
484 the name of a container or an input device. If not specified the
485 format is guessed from @var{movie_name} or by probing.
488 Specify the seek point in seconds, the frames will be output
489 starting from this seek point, the parameter is evaluated with
490 @code{av_strtod} so the numerical value may be suffixed by an IS
491 postfix. Default value is "0".
493 @item stream_index, si
494 Specify the index of the audio stream to read. If the value is -1,
495 the best suited audio stream will be automatically selected. Default
502 Null audio source, return unprocessed audio frames. It is mainly useful
503 as a template and to be employed in analysis / debugging tools, or as
504 the source for filters which ignore the input data (for example the sox
507 It accepts an optional sequence of @var{key}=@var{value} pairs,
510 The description of the accepted options follows.
515 Specify the sample rate, and defaults to 44100.
517 @item channel_layout, cl
519 Specify the channel layout, and can be either an integer or a string
520 representing a channel layout. The default value of @var{channel_layout}
523 Check the channel_layout_map definition in
524 @file{libavcodec/audioconvert.c} for the mapping between strings and
525 channel layout values.
528 Set the number of samples per requested frames.
532 Follow some examples:
534 # set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
535 anullsrc=r=48000:cl=4
538 anullsrc=r=48000:cl=mono
541 @c man end AUDIO SOURCES
544 @c man begin AUDIO SINKS
546 Below is a description of the currently available audio sinks.
550 Buffer audio frames, and make them available to the end of filter chain.
552 This sink is mainly intended for programmatic use, in particular
553 through the interface defined in @file{libavfilter/buffersink.h}.
555 It requires a pointer to an AVABufferSinkContext structure, which
556 defines the incoming buffers' formats, to be passed as the opaque
557 parameter to @code{avfilter_init_filter} for initialization.
561 Null audio sink, do absolutely nothing with the input audio. It is
562 mainly useful as a template and to be employed in analysis / debugging
565 @c man end AUDIO SINKS
567 @chapter Video Filters
568 @c man begin VIDEO FILTERS
570 When you configure your FFmpeg build, you can disable any of the
571 existing filters using --disable-filters.
572 The configure output will show the video filters included in your
575 Below is a description of the currently available video filters.
579 Detect frames that are (almost) completely black. Can be useful to
580 detect chapter transitions or commercials. Output lines consist of
581 the frame number of the detected frame, the percentage of blackness,
582 the position in the file if known or -1 and the timestamp in seconds.
584 In order to display the output lines, you need to set the loglevel at
585 least to the AV_LOG_INFO value.
587 The filter accepts the syntax:
589 blackframe[=@var{amount}:[@var{threshold}]]
592 @var{amount} is the percentage of the pixels that have to be below the
593 threshold, and defaults to 98.
595 @var{threshold} is the threshold below which a pixel value is
596 considered black, and defaults to 32.
600 Apply boxblur algorithm to the input video.
602 This filter accepts the parameters:
603 @var{luma_radius}:@var{luma_power}:@var{chroma_radius}:@var{chroma_power}:@var{alpha_radius}:@var{alpha_power}
605 Chroma and alpha parameters are optional, if not specified they default
606 to the corresponding values set for @var{luma_radius} and
609 @var{luma_radius}, @var{chroma_radius}, and @var{alpha_radius} represent
610 the radius in pixels of the box used for blurring the corresponding
611 input plane. They are expressions, and can contain the following
615 the input width and heigth in pixels
618 the input chroma image width and height in pixels
621 horizontal and vertical chroma subsample values. For example for the
622 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
625 The radius must be a non-negative number, and must not be greater than
626 the value of the expression @code{min(w,h)/2} for the luma and alpha planes,
627 and of @code{min(cw,ch)/2} for the chroma planes.
629 @var{luma_power}, @var{chroma_power}, and @var{alpha_power} represent
630 how many times the boxblur filter is applied to the corresponding
633 Some examples follow:
638 Apply a boxblur filter with luma, chroma, and alpha radius
645 Set luma radius to 2, alpha and chroma radius to 0
651 Set luma and chroma radius to a fraction of the video dimension
653 boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
660 Copy the input source unchanged to the output. Mainly useful for
665 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
667 The parameters are expressions containing the following constants:
671 the computed values for @var{x} and @var{y}. They are evaluated for
675 the input width and height
678 same as @var{in_w} and @var{in_h}
681 the output (cropped) width and height
684 same as @var{out_w} and @var{out_h}
687 same as @var{iw} / @var{ih}
690 input sample aspect ratio
693 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
696 horizontal and vertical chroma subsample values. For example for the
697 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
700 the number of input frame, starting from 0
703 the position in the file of the input frame, NAN if unknown
706 timestamp expressed in seconds, NAN if the input timestamp is unknown
710 The @var{out_w} and @var{out_h} parameters specify the expressions for
711 the width and height of the output (cropped) video. They are
712 evaluated just at the configuration of the filter.
714 The default value of @var{out_w} is "in_w", and the default value of
715 @var{out_h} is "in_h".
717 The expression for @var{out_w} may depend on the value of @var{out_h},
718 and the expression for @var{out_h} may depend on @var{out_w}, but they
719 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
720 evaluated after @var{out_w} and @var{out_h}.
722 The @var{x} and @var{y} parameters specify the expressions for the
723 position of the top-left corner of the output (non-cropped) area. They
724 are evaluated for each frame. If the evaluated value is not valid, it
725 is approximated to the nearest valid value.
727 The default value of @var{x} is "(in_w-out_w)/2", and the default
728 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
729 the center of the input image.
731 The expression for @var{x} may depend on @var{y}, and the expression
732 for @var{y} may depend on @var{x}.
734 Follow some examples:
736 # crop the central input area with size 100x100
739 # crop the central input area with size 2/3 of the input video
740 "crop=2/3*in_w:2/3*in_h"
742 # crop the input video central square
745 # delimit the rectangle with the top-left corner placed at position
746 # 100:100 and the right-bottom corner corresponding to the right-bottom
747 # corner of the input image.
748 crop=in_w-100:in_h-100:100:100
750 # crop 10 pixels from the left and right borders, and 20 pixels from
751 # the top and bottom borders
752 "crop=in_w-2*10:in_h-2*20"
754 # keep only the bottom right quarter of the input image
755 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
757 # crop height for getting Greek harmony
758 "crop=in_w:1/PHI*in_w"
761 "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)"
763 # erratic camera effect depending on timestamp
764 "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)"
766 # set x depending on the value of y
767 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
772 Auto-detect crop size.
774 Calculate necessary cropping parameters and prints the recommended
775 parameters through the logging system. The detected dimensions
776 correspond to the non-black area of the input video.
778 It accepts the syntax:
780 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
786 Threshold, which can be optionally specified from nothing (0) to
787 everything (255), defaults to 24.
790 Value which the width/height should be divisible by, defaults to
791 16. The offset is automatically adjusted to center the video. Use 2 to
792 get only even dimensions (needed for 4:2:2 video). 16 is best when
793 encoding to most video codecs.
796 Counter that determines after how many frames cropdetect will reset
797 the previously detected largest video area and start over to detect
798 the current optimal crop area. Defaults to 0.
800 This can be useful when channel logos distort the video area. 0
801 indicates never reset and return the largest area encountered during
807 Suppress a TV station logo by a simple interpolation of the surrounding
808 pixels. Just set a rectangle covering the logo and watch it disappear
809 (and sometimes something even uglier appear - your mileage may vary).
811 The filter accepts parameters as a string of the form
812 "@var{x}:@var{y}:@var{w}:@var{h}:@var{band}", or as a list of
813 @var{key}=@var{value} pairs, separated by ":".
815 The description of the accepted parameters follows.
820 Specify the top left corner coordinates of the logo. They must be
824 Specify the width and height of the logo to clear. They must be
828 Specify the thickness of the fuzzy edge of the rectangle (added to
829 @var{w} and @var{h}). The default value is 4.
832 When set to 1, a green rectangle is drawn on the screen to simplify
833 finding the right @var{x}, @var{y}, @var{w}, @var{h} parameters, and
834 @var{band} is set to 4. The default value is 0.
838 Some examples follow.
843 Set a rectangle covering the area with top left corner coordinates 0,0
844 and size 100x77, setting a band of size 10:
850 As the previous example, but use named options:
852 delogo=x=0:y=0:w=100:h=77:band=10
859 Attempt to fix small changes in horizontal and/or vertical shift. This
860 filter helps remove camera shake from hand-holding a camera, bumping a
861 tripod, moving on a vehicle, etc.
863 The filter accepts parameters as a string of the form
864 "@var{x}:@var{y}:@var{w}:@var{h}:@var{rx}:@var{ry}:@var{edge}:@var{blocksize}:@var{contrast}:@var{search}:@var{filename}"
866 A description of the accepted parameters follows.
871 Specify a rectangular area where to limit the search for motion
873 If desired the search for motion vectors can be limited to a
874 rectangular area of the frame defined by its top left corner, width
875 and height. These parameters have the same meaning as the drawbox
876 filter which can be used to visualise the position of the bounding
879 This is useful when simultaneous movement of subjects within the frame
880 might be confused for camera motion by the motion vector search.
882 If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1
883 then the full frame is used. This allows later options to be set
884 without specifying the bounding box for the motion vector search.
886 Default - search the whole frame.
889 Specify the maximum extent of movement in x and y directions in the
890 range 0-64 pixels. Default 16.
893 Specify how to generate pixels to fill blanks at the edge of the
894 frame. An integer from 0 to 3 as follows:
897 Fill zeroes at blank locations
899 Original image at blank locations
901 Extruded edge value at blank locations
903 Mirrored edge at blank locations
906 The default setting is mirror edge at blank locations.
909 Specify the blocksize to use for motion search. Range 4-128 pixels,
913 Specify the contrast threshold for blocks. Only blocks with more than
914 the specified contrast (difference between darkest and lightest
915 pixels) will be considered. Range 1-255, default 125.
918 Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
919 search. Default - exhaustive search.
922 If set then a detailed log of the motion search is written to the
929 Draw a colored box on the input image.
931 It accepts the syntax:
933 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
939 Specify the top left corner coordinates of the box. Default to 0.
942 Specify the width and height of the box, if 0 they are interpreted as
943 the input width and height. Default to 0.
946 Specify the color of the box to write, it can be the name of a color
947 (case insensitive match) or a 0xRRGGBB[AA] sequence.
950 Follow some examples:
952 # draw a black box around the edge of the input image
955 # draw a box with color red and an opacity of 50%
956 drawbox=10:20:200:60:red@@0.5"
961 Draw text string or text from specified file on top of video using the
964 To enable compilation of this filter you need to configure FFmpeg with
965 @code{--enable-libfreetype}.
967 The filter also recognizes strftime() sequences in the provided text
968 and expands them accordingly. Check the documentation of strftime().
970 The filter accepts parameters as a list of @var{key}=@var{value} pairs,
973 The description of the accepted parameters follows.
978 The font file to be used for drawing text. Path must be included.
979 This parameter is mandatory.
982 The text string to be drawn. The text must be a sequence of UTF-8
984 This parameter is mandatory if no file is specified with the parameter
988 A text file containing text to be drawn. The text must be a sequence
989 of UTF-8 encoded characters.
991 This parameter is mandatory if no text string is specified with the
992 parameter @var{text}.
994 If both text and textfile are specified, an error is thrown.
997 The expressions which specify the offsets where text will be drawn
998 within the video frame. They are relative to the top/left border of the
1001 The default value of @var{x} and @var{y} is "0".
1003 See below for the list of accepted constants.
1006 The font size to be used for drawing text.
1007 The default value of @var{fontsize} is 16.
1010 The color to be used for drawing fonts.
1011 Either a string (e.g. "red") or in 0xRRGGBB[AA] format
1012 (e.g. "0xff000033"), possibly followed by an alpha specifier.
1013 The default value of @var{fontcolor} is "black".
1016 The color to be used for drawing box around text.
1017 Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
1018 (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1019 The default value of @var{boxcolor} is "white".
1022 Used to draw a box around text using background color.
1023 Value should be either 1 (enable) or 0 (disable).
1024 The default value of @var{box} is 0.
1026 @item shadowx, shadowy
1027 The x and y offsets for the text shadow position with respect to the
1028 position of the text. They can be either positive or negative
1029 values. Default value for both is "0".
1032 The color to be used for drawing a shadow behind the drawn text. It
1033 can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
1034 form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
1035 The default value of @var{shadowcolor} is "black".
1038 Flags to be used for loading the fonts.
1040 The flags map the corresponding flags supported by libfreetype, and are
1041 a combination of the following values:
1048 @item vertical_layout
1049 @item force_autohint
1052 @item ignore_global_advance_width
1054 @item ignore_transform
1061 Default value is "render".
1063 For more information consult the documentation for the FT_LOAD_*
1067 The size in number of spaces to use for rendering the tab.
1071 The parameters for @var{x} and @var{y} are expressions containing the
1072 following constants:
1076 the input width and heigth
1079 the width of the rendered text
1082 the height of the rendered text
1085 the height of each text line
1088 input sample aspect ratio
1091 input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}
1094 horizontal and vertical chroma subsample values. For example for the
1095 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1098 maximum glyph width, that is the maximum width for all the glyphs
1099 contained in the rendered text
1102 maximum glyph height, that is the maximum height for all the glyphs
1103 contained in the rendered text, it is equivalent to @var{ascent} -
1106 @item max_glyph_a, ascent
1108 the maximum distance from the baseline to the highest/upper grid
1109 coordinate used to place a glyph outline point, for all the rendered
1111 It is a positive value, due to the grid's orientation with the Y axis
1114 @item max_glyph_d, descent
1115 the maximum distance from the baseline to the lowest grid coordinate
1116 used to place a glyph outline point, for all the rendered glyphs.
1117 This is a negative value, due to the grid's orientation, with the Y axis
1121 the number of input frame, starting from 0
1124 timestamp expressed in seconds, NAN if the input timestamp is unknown
1127 Some examples follow.
1132 Draw "Test Text" with font FreeSerif, using the default values for the
1133 optional parameters.
1136 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
1140 Draw 'Test Text' with font FreeSerif of size 24 at position x=100
1141 and y=50 (counting from the top-left corner of the screen), text is
1142 yellow with a red box around it. Both the text and the box have an
1146 drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
1147 x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
1150 Note that the double quotes are not necessary if spaces are not used
1151 within the parameter list.
1154 Show the text at the center of the video frame:
1156 drawtext=fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h-line_h)/2"
1160 Show a text line sliding from right to left in the last row of the video
1161 frame. The file @file{LONG_LINE} is assumed to contain a single line
1164 drawtext=fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t
1168 Show the content of file @file{CREDITS} off the bottom of the frame and scroll up.
1170 drawtext=fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
1174 Draw a single green letter "g", at the center of the input video.
1175 The glyph baseline is placed at half screen height.
1177 drawtext=fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent
1182 For more information about libfreetype, check:
1183 @url{http://www.freetype.org/}.
1187 Apply fade-in/out effect to input video.
1189 It accepts the parameters:
1190 @var{type}:@var{start_frame}:@var{nb_frames}[:@var{options}]
1192 @var{type} specifies if the effect type, can be either "in" for
1193 fade-in, or "out" for a fade-out effect.
1195 @var{start_frame} specifies the number of the start frame for starting
1196 to apply the fade effect.
1198 @var{nb_frames} specifies the number of frames for which the fade
1199 effect has to last. At the end of the fade-in effect the output video
1200 will have the same intensity as the input video, at the end of the
1201 fade-out transition the output video will be completely black.
1203 @var{options} is an optional sequence of @var{key}=@var{value} pairs,
1204 separated by ":". The description of the accepted options follows.
1211 @item start_frame, s
1212 See @var{start_frame}.
1215 See @var{nb_frames}.
1218 If set to 1, fade only alpha channel, if one exists on the input.
1222 A few usage examples follow, usable too as test scenarios.
1224 # fade in first 30 frames of video
1227 # fade out last 45 frames of a 200-frame video
1230 # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
1231 fade=in:0:25, fade=out:975:25
1233 # make first 5 frames black, then fade in from frame 5-24
1236 # fade in alpha over first 25 frames of video
1237 fade=in:0:25:alpha=1
1242 Transform the field order of the input video.
1244 It accepts one parameter which specifies the required field order that
1245 the input interlaced video will be transformed to. The parameter can
1246 assume one of the following values:
1250 output bottom field first
1252 output top field first
1255 Default value is "tff".
1257 Transformation is achieved by shifting the picture content up or down
1258 by one line, and filling the remaining line with appropriate picture content.
1259 This method is consistent with most broadcast field order converters.
1261 If the input video is not flagged as being interlaced, or it is already
1262 flagged as being of the required output field order then this filter does
1263 not alter the incoming video.
1265 This filter is very useful when converting to or from PAL DV material,
1266 which is bottom field first.
1270 ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
1275 Buffer input images and send them when they are requested.
1277 This filter is mainly useful when auto-inserted by the libavfilter
1280 The filter does not take parameters.
1284 Convert the input video to one of the specified pixel formats.
1285 Libavfilter will try to pick one that is supported for the input to
1288 The filter accepts a list of pixel format names, separated by ":",
1289 for example "yuv420p:monow:rgb24".
1291 Some examples follow:
1293 # convert the input video to the format "yuv420p"
1296 # convert the input video to any of the formats in the list
1297 format=yuv420p:yuv444p:yuv410p
1303 Apply a frei0r effect to the input video.
1305 To enable compilation of this filter you need to install the frei0r
1306 header and configure FFmpeg with --enable-frei0r.
1308 The filter supports the syntax:
1310 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
1313 @var{filter_name} is the name to the frei0r effect to load. If the
1314 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
1315 is searched in each one of the directories specified by the colon
1316 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
1317 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
1318 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
1320 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
1321 for the frei0r effect.
1323 A frei0r effect parameter can be a boolean (whose values are specified
1324 with "y" and "n"), a double, a color (specified by the syntax
1325 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
1326 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
1327 description), a position (specified by the syntax @var{X}/@var{Y},
1328 @var{X} and @var{Y} being float numbers) and a string.
1330 The number and kind of parameters depend on the loaded effect. If an
1331 effect parameter is not specified the default value is set.
1333 Some examples follow:
1335 # apply the distort0r effect, set the first two double parameters
1336 frei0r=distort0r:0.5:0.01
1338 # apply the colordistance effect, takes a color as first parameter
1339 frei0r=colordistance:0.2/0.3/0.4
1340 frei0r=colordistance:violet
1341 frei0r=colordistance:0x112233
1343 # apply the perspective effect, specify the top left and top right
1345 frei0r=perspective:0.2/0.2:0.8/0.2
1348 For more information see:
1349 @url{http://piksel.org/frei0r}
1353 Fix the banding artifacts that are sometimes introduced into nearly flat
1354 regions by truncation to 8bit colordepth.
1355 Interpolate the gradients that should go where the bands are, and
1358 This filter is designed for playback only. Do not use it prior to
1359 lossy compression, because compression tends to lose the dither and
1360 bring back the bands.
1362 The filter takes two optional parameters, separated by ':':
1363 @var{strength}:@var{radius}
1365 @var{strength} is the maximum amount by which the filter will change
1366 any one pixel. Also the threshold for detecting nearly flat
1367 regions. Acceptable values range from .51 to 255, default value is
1368 1.2, out-of-range values will be clipped to the valid range.
1370 @var{radius} is the neighborhood to fit the gradient to. A larger
1371 radius makes for smoother gradients, but also prevents the filter from
1372 modifying the pixels near detailed regions. Acceptable values are
1373 8-32, default value is 16, out-of-range values will be clipped to the
1377 # default parameters
1386 Flip the input video horizontally.
1388 For example to horizontally flip the video in input with
1391 ffmpeg -i in.avi -vf "hflip" out.avi
1396 High precision/quality 3d denoise filter. This filter aims to reduce
1397 image noise producing smooth images and making still images really
1398 still. It should enhance compressibility.
1400 It accepts the following optional parameters:
1401 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
1405 a non-negative float number which specifies spatial luma strength,
1408 @item chroma_spatial
1409 a non-negative float number which specifies spatial chroma strength,
1410 defaults to 3.0*@var{luma_spatial}/4.0
1413 a float number which specifies luma temporal strength, defaults to
1414 6.0*@var{luma_spatial}/4.0
1417 a float number which specifies chroma temporal strength, defaults to
1418 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
1421 @section lut, lutrgb, lutyuv
1423 Compute a look-up table for binding each pixel component input value
1424 to an output value, and apply it to input video.
1426 @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb}
1427 to an RGB input video.
1429 These filters accept in input a ":"-separated list of options, which
1430 specify the expressions used for computing the lookup table for the
1431 corresponding pixel component values.
1433 The @var{lut} filter requires either YUV or RGB pixel formats in
1434 input, and accepts the options:
1437 first pixel component
1439 second pixel component
1441 third pixel component
1443 fourth pixel component, corresponds to the alpha component
1446 The exact component associated to each option depends on the format in
1449 The @var{lutrgb} filter requires RGB pixel formats in input, and
1450 accepts the options:
1462 The @var{lutyuv} filter requires YUV pixel formats in input, and
1463 accepts the options:
1466 Y/luminance component
1475 The expressions can contain the following constants and functions:
1479 the input width and heigth
1482 input value for the pixel component
1485 the input value clipped in the @var{minval}-@var{maxval} range
1488 maximum value for the pixel component
1491 minimum value for the pixel component
1494 the negated value for the pixel component value clipped in the
1495 @var{minval}-@var{maxval} range , it corresponds to the expression
1496 "maxval-clipval+minval"
1499 the computed value in @var{val} clipped in the
1500 @var{minval}-@var{maxval} range
1502 @item gammaval(gamma)
1503 the computed gamma correction value of the pixel component value
1504 clipped in the @var{minval}-@var{maxval} range, corresponds to the
1506 "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval"
1510 All expressions default to "val".
1512 Some examples follow:
1514 # negate input video
1515 lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
1516 lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
1518 # the above is the same as
1519 lutrgb="r=negval:g=negval:b=negval"
1520 lutyuv="y=negval:u=negval:v=negval"
1525 # remove chroma components, turns the video into a graytone image
1526 lutyuv="u=128:v=128"
1528 # apply a luma burning effect
1531 # remove green and blue components
1534 # set a constant alpha channel value on input
1535 format=rgba,lutrgb=a="maxval-minval/2"
1537 # correct luminance gamma by a 0.5 factor
1538 lutyuv=y=gammaval(0.5)
1543 Apply an MPlayer filter to the input video.
1545 This filter provides a wrapper around most of the filters of
1548 This wrapper is considered experimental. Some of the wrapped filters
1549 may not work properly and we may drop support for them, as they will
1550 be implemented natively into FFmpeg. Thus you should avoid
1551 depending on them when writing portable scripts.
1553 The filters accepts the parameters:
1554 @var{filter_name}[:=]@var{filter_params}
1556 @var{filter_name} is the name of a supported MPlayer filter,
1557 @var{filter_params} is a string containing the parameters accepted by
1560 The list of the currently supported filters follows:
1614 The parameter syntax and behavior for the listed filters are the same
1615 of the corresponding MPlayer filters. For detailed instructions check
1616 the "VIDEO FILTERS" section in the MPlayer manual.
1618 Some examples follow:
1620 # remove a logo by interpolating the surrounding pixels
1621 mp=delogo=200:200:80:20:1
1623 # adjust gamma, brightness, contrast
1626 # tweak hue and saturation
1630 See also mplayer(1), @url{http://www.mplayerhq.hu/}.
1636 This filter accepts an integer in input, if non-zero it negates the
1637 alpha component (if available). The default value in input is 0.
1641 Force libavfilter not to use any of the specified pixel formats for the
1642 input to the next filter.
1644 The filter accepts a list of pixel format names, separated by ":",
1645 for example "yuv420p:monow:rgb24".
1647 Some examples follow:
1649 # force libavfilter to use a format different from "yuv420p" for the
1650 # input to the vflip filter
1651 noformat=yuv420p,vflip
1653 # convert the input video to any of the formats not contained in the list
1654 noformat=yuv420p:yuv444p:yuv410p
1659 Pass the video source unchanged to the output.
1663 Apply video transform using libopencv.
1665 To enable this filter install libopencv library and headers and
1666 configure FFmpeg with --enable-libopencv.
1668 The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
1670 @var{filter_name} is the name of the libopencv filter to apply.
1672 @var{filter_params} specifies the parameters to pass to the libopencv
1673 filter. If not specified the default values are assumed.
1675 Refer to the official libopencv documentation for more precise
1677 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
1679 Follows the list of supported libopencv filters.
1684 Dilate an image by using a specific structuring element.
1685 This filter corresponds to the libopencv function @code{cvDilate}.
1687 It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
1689 @var{struct_el} represents a structuring element, and has the syntax:
1690 @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
1692 @var{cols} and @var{rows} represent the number of colums and rows of
1693 the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
1694 point, and @var{shape} the shape for the structuring element, and
1695 can be one of the values "rect", "cross", "ellipse", "custom".
1697 If the value for @var{shape} is "custom", it must be followed by a
1698 string of the form "=@var{filename}". The file with name
1699 @var{filename} is assumed to represent a binary image, with each
1700 printable character corresponding to a bright pixel. When a custom
1701 @var{shape} is used, @var{cols} and @var{rows} are ignored, the number
1702 or columns and rows of the read file are assumed instead.
1704 The default value for @var{struct_el} is "3x3+0x0/rect".
1706 @var{nb_iterations} specifies the number of times the transform is
1707 applied to the image, and defaults to 1.
1709 Follow some example:
1711 # use the default values
1714 # dilate using a structuring element with a 5x5 cross, iterate two times
1715 ocv=dilate=5x5+2x2/cross:2
1717 # read the shape from the file diamond.shape, iterate two times
1718 # the file diamond.shape may contain a pattern of characters like this:
1724 # the specified cols and rows are ignored (but not the anchor point coordinates)
1725 ocv=0x0+2x2/custom=diamond.shape:2
1730 Erode an image by using a specific structuring element.
1731 This filter corresponds to the libopencv function @code{cvErode}.
1733 The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
1734 with the same syntax and semantics as the @ref{dilate} filter.
1738 Smooth the input video.
1740 The filter takes the following parameters:
1741 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
1743 @var{type} is the type of smooth filter to apply, and can be one of
1744 the following values: "blur", "blur_no_scale", "median", "gaussian",
1745 "bilateral". The default value is "gaussian".
1747 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
1748 parameters whose meanings depend on smooth type. @var{param1} and
1749 @var{param2} accept integer positive values or 0, @var{param3} and
1750 @var{param4} accept float values.
1752 The default value for @var{param1} is 3, the default value for the
1753 other parameters is 0.
1755 These parameters correspond to the parameters assigned to the
1756 libopencv function @code{cvSmooth}.
1760 Overlay one video on top of another.
1762 It takes two inputs and one output, the first input is the "main"
1763 video on which the second input is overlayed.
1765 It accepts the parameters: @var{x}:@var{y}[:@var{options}].
1767 @var{x} is the x coordinate of the overlayed video on the main video,
1768 @var{y} is the y coordinate. @var{x} and @var{y} are expressions containing
1769 the following parameters:
1772 @item main_w, main_h
1773 main input width and height
1776 same as @var{main_w} and @var{main_h}
1778 @item overlay_w, overlay_h
1779 overlay input width and height
1782 same as @var{overlay_w} and @var{overlay_h}
1785 @var{options} is an optional list of @var{key}=@var{value} pairs,
1788 The description of the accepted options follows.
1792 If set to 1, force the filter to accept inputs in the RGB
1793 colorspace. Default value is 0.
1796 Be aware that frames are taken from each input video in timestamp
1797 order, hence, if their initial timestamps differ, it is a a good idea
1798 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
1799 have them begin in the same zero timestamp, as it does the example for
1800 the @var{movie} filter.
1802 Follow some examples:
1804 # draw the overlay at 10 pixels from the bottom right
1805 # corner of the main video.
1806 overlay=main_w-overlay_w-10:main_h-overlay_h-10
1808 # insert a transparent PNG logo in the bottom left corner of the input
1809 movie=logo.png [logo];
1810 [in][logo] overlay=10:main_h-overlay_h-10 [out]
1812 # insert 2 different transparent PNG logos (second logo on bottom
1814 movie=logo1.png [logo1];
1815 movie=logo2.png [logo2];
1816 [in][logo1] overlay=10:H-h-10 [in+logo1];
1817 [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
1819 # add a transparent color layer on top of the main video,
1820 # WxH specifies the size of the main input to the overlay filter
1821 color=red@.3:WxH [over]; [in][over] overlay [out]
1824 You can chain together more overlays but the efficiency of such
1825 approach is yet to be tested.
1829 Add paddings to the input image, and places the original input at the
1830 given coordinates @var{x}, @var{y}.
1832 It accepts the following parameters:
1833 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
1835 The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
1836 expressions containing the following constants:
1840 the input video width and height
1843 same as @var{in_w} and @var{in_h}
1846 the output width and height, that is the size of the padded area as
1847 specified by the @var{width} and @var{height} expressions
1850 same as @var{out_w} and @var{out_h}
1853 x and y offsets as specified by the @var{x} and @var{y}
1854 expressions, or NAN if not yet specified
1857 same as @var{iw} / @var{ih}
1860 input sample aspect ratio
1863 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1866 horizontal and vertical chroma subsample values. For example for the
1867 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1870 Follows the description of the accepted parameters.
1875 Specify the size of the output image with the paddings added. If the
1876 value for @var{width} or @var{height} is 0, the corresponding input size
1877 is used for the output.
1879 The @var{width} expression can reference the value set by the
1880 @var{height} expression, and viceversa.
1882 The default value of @var{width} and @var{height} is 0.
1886 Specify the offsets where to place the input image in the padded area
1887 with respect to the top/left border of the output image.
1889 The @var{x} expression can reference the value set by the @var{y}
1890 expression, and viceversa.
1892 The default value of @var{x} and @var{y} is 0.
1896 Specify the color of the padded area, it can be the name of a color
1897 (case insensitive match) or a 0xRRGGBB[AA] sequence.
1899 The default value of @var{color} is "black".
1903 Some examples follow:
1906 # Add paddings with color "violet" to the input video. Output video
1907 # size is 640x480, the top-left corner of the input video is placed at
1909 pad=640:480:0:40:violet
1911 # pad the input to get an output with dimensions increased bt 3/2,
1912 # and put the input video at the center of the padded area
1913 pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
1915 # pad the input to get a squared output with size equal to the maximum
1916 # value between the input width and height, and put the input video at
1917 # the center of the padded area
1918 pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
1920 # pad the input to get a final w/h ratio of 16:9
1921 pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
1923 # for anamorphic video, in order to set the output display aspect ratio,
1924 # it is necessary to use sar in the expression, according to the relation:
1925 # (ih * X / ih) * sar = output_dar
1926 # X = output_dar / sar
1927 pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
1929 # double output size and put the input video in the bottom-right
1930 # corner of the output padded area
1931 pad="2*iw:2*ih:ow-iw:oh-ih"
1934 @section pixdesctest
1936 Pixel format descriptor test filter, mainly useful for internal
1937 testing. The output video should be equal to the input video.
1941 format=monow, pixdesctest
1944 can be used to test the monowhite pixel format descriptor definition.
1948 Scale the input video to @var{width}:@var{height}[:@var{interl}=@{1|-1@}] and/or convert the image format.
1950 The parameters @var{width} and @var{height} are expressions containing
1951 the following constants:
1955 the input width and height
1958 same as @var{in_w} and @var{in_h}
1961 the output (cropped) width and height
1964 same as @var{out_w} and @var{out_h}
1967 same as @var{iw} / @var{ih}
1970 input sample aspect ratio
1973 input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar}
1976 input sample aspect ratio
1979 horizontal and vertical chroma subsample values. For example for the
1980 pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1983 If the input image format is different from the format requested by
1984 the next filter, the scale filter will convert the input to the
1987 If the value for @var{width} or @var{height} is 0, the respective input
1988 size is used for the output.
1990 If the value for @var{width} or @var{height} is -1, the scale filter will
1991 use, for the respective output size, a value that maintains the aspect
1992 ratio of the input image.
1994 The default value of @var{width} and @var{height} is 0.
1996 Valid values for the optional parameter @var{interl} are:
2000 force interlaced aware scaling
2003 select interlaced aware scaling depending on whether the source frames
2004 are flagged as interlaced or not
2007 Some examples follow:
2009 # scale the input video to a size of 200x100.
2012 # scale the input to 2x
2014 # the above is the same as
2017 # scale the input to half size
2020 # increase the width, and set the height to the same size
2023 # seek for Greek harmony
2027 # increase the height, and set the width to 3/2 of the height
2030 # increase the size, but make the size a multiple of the chroma
2031 scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
2033 # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
2034 scale='min(500\, iw*3/2):-1'
2038 Select frames to pass in output.
2040 It accepts in input an expression, which is evaluated for each input
2041 frame. If the expression is evaluated to a non-zero value, the frame
2042 is selected and passed to the output, otherwise it is discarded.
2044 The expression can contain the following constants:
2048 the sequential number of the filtered frame, starting from 0
2051 the sequential number of the selected frame, starting from 0
2053 @item prev_selected_n
2054 the sequential number of the last selected frame, NAN if undefined
2057 timebase of the input timestamps
2060 the PTS (Presentation TimeStamp) of the filtered video frame,
2061 expressed in @var{TB} units, NAN if undefined
2064 the PTS (Presentation TimeStamp) of the filtered video frame,
2065 expressed in seconds, NAN if undefined
2068 the PTS of the previously filtered video frame, NAN if undefined
2070 @item prev_selected_pts
2071 the PTS of the last previously filtered video frame, NAN if undefined
2073 @item prev_selected_t
2074 the PTS of the last previously selected video frame, NAN if undefined
2077 the PTS of the first video frame in the video, NAN if undefined
2080 the time of the first video frame in the video, NAN if undefined
2083 the type of the filtered frame, can assume one of the following
2095 @item interlace_type
2096 the frame interlace type, can assume one of the following values:
2099 the frame is progressive (not interlaced)
2101 the frame is top-field-first
2103 the frame is bottom-field-first
2107 1 if the filtered frame is a key-frame, 0 otherwise
2110 the position in the file of the filtered frame, -1 if the information
2111 is not available (e.g. for synthetic video)
2114 The default value of the select expression is "1".
2116 Some examples follow:
2119 # select all frames in input
2122 # the above is the same as:
2128 # select only I-frames
2129 select='eq(pict_type\,I)'
2131 # select one frame every 100
2132 select='not(mod(n\,100))'
2134 # select only frames contained in the 10-20 time interval
2135 select='gte(t\,10)*lte(t\,20)'
2137 # select only I frames contained in the 10-20 time interval
2138 select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
2140 # select frames with a minimum distance of 10 seconds
2141 select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
2147 Set the Display Aspect Ratio for the filter output video.
2149 This is done by changing the specified Sample (aka Pixel) Aspect
2150 Ratio, according to the following equation:
2151 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2153 Keep in mind that this filter does not modify the pixel dimensions of
2154 the video frame. Also the display aspect ratio set by this filter may
2155 be changed by later filters in the filterchain, e.g. in case of
2156 scaling or if another "setdar" or a "setsar" filter is applied.
2158 The filter accepts a parameter string which represents the wanted
2159 display aspect ratio.
2160 The parameter can be a floating point number string, or an expression
2161 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
2162 numerator and denominator of the aspect ratio.
2163 If the parameter is not specified, it is assumed the value "0:1".
2165 For example to change the display aspect ratio to 16:9, specify:
2168 # the above is equivalent to
2172 See also the @ref{setsar} filter documentation.
2176 Change the PTS (presentation timestamp) of the input video frames.
2178 Accept in input an expression evaluated through the eval API, which
2179 can contain the following constants:
2183 the presentation timestamp in input
2186 the count of the input frame, starting from 0.
2189 the PTS of the first video frame
2192 tell if the current frame is interlaced
2195 original position in the file of the frame, or undefined if undefined
2196 for the current frame
2206 Some examples follow:
2209 # start counting PTS from zero
2221 # fixed rate 25 fps with some jitter
2222 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
2228 Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
2230 Note that as a consequence of the application of this filter, the
2231 output display aspect ratio will change according to the following
2233 @math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
2235 Keep in mind that the sample aspect ratio set by this filter may be
2236 changed by later filters in the filterchain, e.g. if another "setsar"
2237 or a "setdar" filter is applied.
2239 The filter accepts a parameter string which represents the wanted
2240 sample aspect ratio.
2241 The parameter can be a floating point number string, or an expression
2242 of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
2243 numerator and denominator of the aspect ratio.
2244 If the parameter is not specified, it is assumed the value "0:1".
2246 For example to change the sample aspect ratio to 10:11, specify:
2253 Set the timebase to use for the output frames timestamps.
2254 It is mainly useful for testing timebase configuration.
2256 It accepts in input an arithmetic expression representing a rational.
2257 The expression can contain the constants "AVTB" (the
2258 default timebase), and "intb" (the input timebase).
2260 The default value for the input is "intb".
2262 Follow some examples.
2265 # set the timebase to 1/25
2268 # set the timebase to 1/10
2271 #set the timebase to 1001/1000
2274 #set the timebase to 2*intb
2277 #set the default timebase value
2283 Show a line containing various information for each input video frame.
2284 The input video is not modified.
2286 The shown line contains a sequence of key/value pairs of the form
2287 @var{key}:@var{value}.
2289 A description of each shown parameter follows:
2293 sequential number of the input frame, starting from 0
2296 Presentation TimeStamp of the input frame, expressed as a number of
2297 time base units. The time base unit depends on the filter input pad.
2300 Presentation TimeStamp of the input frame, expressed as a number of
2304 position of the frame in the input stream, -1 if this information in
2305 unavailable and/or meanigless (for example in case of synthetic video)
2311 sample aspect ratio of the input frame, expressed in the form
2315 size of the input frame, expressed in the form
2316 @var{width}x@var{height}
2319 interlaced mode ("P" for "progressive", "T" for top field first, "B"
2320 for bottom field first)
2323 1 if the frame is a key frame, 0 otherwise
2326 picture type of the input frame ("I" for an I-frame, "P" for a
2327 P-frame, "B" for a B-frame, "?" for unknown type).
2328 Check also the documentation of the @code{AVPictureType} enum and of
2329 the @code{av_get_picture_type_char} function defined in
2330 @file{libavutil/avutil.h}.
2333 Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
2335 @item plane_checksum
2336 Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
2337 expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]"
2342 Pass the images of input video on to next video filter as multiple
2346 ffmpeg -i in.avi -vf "slicify=32" out.avi
2349 The filter accepts the slice height as parameter. If the parameter is
2350 not specified it will use the default value of 16.
2352 Adding this in the beginning of filter chains should make filtering
2353 faster due to better use of the memory cache.
2357 Pass on the input video to two outputs. Both outputs are identical to
2362 [in] split [splitout1][splitout2];
2363 [splitout1] crop=100:100:0:0 [cropout];
2364 [splitout2] pad=200:200:100:100 [padout];
2367 will create two separate outputs from the same input, one cropped and
2372 Transpose rows with columns in the input video and optionally flip it.
2374 It accepts a parameter representing an integer, which can assume the
2379 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
2387 Rotate by 90 degrees clockwise, that is:
2395 Rotate by 90 degrees counterclockwise, that is:
2403 Rotate by 90 degrees clockwise and vertically flip, that is:
2413 Sharpen or blur the input video.
2415 It accepts the following parameters:
2416 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
2418 Negative values for the amount will blur the input video, while positive
2419 values will sharpen. All parameters are optional and default to the
2420 equivalent of the string '5:5:1.0:5:5:0.0'.
2425 Set the luma matrix horizontal size. It can be an integer between 3
2426 and 13, default value is 5.
2429 Set the luma matrix vertical size. It can be an integer between 3
2430 and 13, default value is 5.
2433 Set the luma effect strength. It can be a float number between -2.0
2434 and 5.0, default value is 1.0.
2436 @item chroma_msize_x
2437 Set the chroma matrix horizontal size. It can be an integer between 3
2438 and 13, default value is 5.
2440 @item chroma_msize_y
2441 Set the chroma matrix vertical size. It can be an integer between 3
2442 and 13, default value is 5.
2445 Set the chroma effect strength. It can be a float number between -2.0
2446 and 5.0, default value is 0.0.
2451 # Strong luma sharpen effect parameters
2454 # Strong blur of both luma and chroma parameters
2455 unsharp=7:7:-2:7:7:-2
2457 # Use the default values with @command{ffmpeg}
2458 ffmpeg -i in.avi -vf "unsharp" out.mp4
2463 Flip the input video vertically.
2466 ffmpeg -i in.avi -vf "vflip" out.avi
2471 Deinterlace the input video ("yadif" means "yet another deinterlacing
2474 It accepts the optional parameters: @var{mode}:@var{parity}:@var{auto}.
2476 @var{mode} specifies the interlacing mode to adopt, accepts one of the
2481 output 1 frame for each frame
2483 output 1 frame for each field
2485 like 0 but skips spatial interlacing check
2487 like 1 but skips spatial interlacing check
2492 @var{parity} specifies the picture field parity assumed for the input
2493 interlaced video, accepts one of the following values:
2497 assume top field first
2499 assume bottom field first
2501 enable automatic detection
2504 Default value is -1.
2505 If interlacing is unknown or decoder does not export this information,
2506 top field first will be assumed.
2508 @var{auto} specifies if deinterlacer should trust the interlaced flag
2509 and only deinterlace frames marked as interlaced
2513 deinterlace all frames
2515 only deinterlace frames marked as interlaced
2520 @c man end VIDEO FILTERS
2522 @chapter Video Sources
2523 @c man begin VIDEO SOURCES
2525 Below is a description of the currently available video sources.
2529 Buffer video frames, and make them available to the filter chain.
2531 This source is mainly intended for a programmatic use, in particular
2532 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
2534 It accepts the following parameters:
2535 @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}
2537 All the parameters but @var{scale_params} need to be explicitly
2540 Follows the list of the accepted parameters.
2545 Specify the width and height of the buffered video frames.
2547 @item pix_fmt_string
2548 A string representing the pixel format of the buffered video frames.
2549 It may be a number corresponding to a pixel format, or a pixel format
2552 @item timebase_num, timebase_den
2553 Specify numerator and denomitor of the timebase assumed by the
2554 timestamps of the buffered frames.
2556 @item sample_aspect_ratio.num, sample_aspect_ratio.den
2557 Specify numerator and denominator of the sample aspect ratio assumed
2558 by the video frames.
2561 Specify the optional parameters to be used for the scale filter which
2562 is automatically inserted when an input change is detected in the
2563 input size or format.
2568 buffer=320:240:yuv410p:1:24:1:1
2571 will instruct the source to accept video frames with size 320x240 and
2572 with format "yuv410p", assuming 1/24 as the timestamps timebase and
2573 square pixels (1:1 sample aspect ratio).
2574 Since the pixel format with name "yuv410p" corresponds to the number 6
2575 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
2576 this example corresponds to:
2578 buffer=320:240:6:1:24:1:1
2583 Provide an uniformly colored input.
2585 It accepts the following parameters:
2586 @var{color}:@var{frame_size}:@var{frame_rate}
2588 Follows the description of the accepted parameters.
2593 Specify the color of the source. It can be the name of a color (case
2594 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
2595 alpha specifier. The default value is "black".
2598 Specify the size of the sourced video, it may be a string of the form
2599 @var{width}x@var{height}, or the name of a size abbreviation. The
2600 default value is "320x240".
2603 Specify the frame rate of the sourced video, as the number of frames
2604 generated per second. It has to be a string in the format
2605 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2606 number or a valid video frame rate abbreviation. The default value is
2611 For example the following graph description will generate a red source
2612 with an opacity of 0.2, with size "qcif" and a frame rate of 10
2613 frames per second, which will be overlayed over the source connected
2614 to the pad with identifier "in".
2617 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
2622 Read a video stream from a movie container.
2624 It accepts the syntax: @var{movie_name}[:@var{options}] where
2625 @var{movie_name} is the name of the resource to read (not necessarily
2626 a file but also a device or a stream accessed through some protocol),
2627 and @var{options} is an optional sequence of @var{key}=@var{value}
2628 pairs, separated by ":".
2630 The description of the accepted options follows.
2634 @item format_name, f
2635 Specifies the format assumed for the movie to read, and can be either
2636 the name of a container or an input device. If not specified the
2637 format is guessed from @var{movie_name} or by probing.
2639 @item seek_point, sp
2640 Specifies the seek point in seconds, the frames will be output
2641 starting from this seek point, the parameter is evaluated with
2642 @code{av_strtod} so the numerical value may be suffixed by an IS
2643 postfix. Default value is "0".
2645 @item stream_index, si
2646 Specifies the index of the video stream to read. If the value is -1,
2647 the best suited video stream will be automatically selected. Default
2652 This filter allows to overlay a second video on top of main input of
2653 a filtergraph as shown in this graph:
2655 input -----------> deltapts0 --> overlay --> output
2658 movie --> scale--> deltapts1 -------+
2661 Some examples follow:
2663 # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
2664 # on top of the input labelled as "in".
2665 movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2666 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2668 # read from a video4linux2 device, and overlay it on top of the input
2670 movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
2671 [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
2677 Generate various test patterns, as generated by the MPlayer test filter.
2679 The size of the generated video is fixed, and is 256x256.
2680 This source is useful in particular for testing encoding features.
2682 This source accepts an optional sequence of @var{key}=@var{value} pairs,
2683 separated by ":". The description of the accepted options follows.
2688 Specify the frame rate of the sourced video, as the number of frames
2689 generated per second. It has to be a string in the format
2690 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2691 number or a valid video frame rate abbreviation. The default value is
2695 Set the video duration of the sourced video. The accepted syntax is:
2697 [-]HH[:MM[:SS[.m...]]]
2700 See also the function @code{av_parse_time()}.
2702 If not specified, or the expressed duration is negative, the video is
2703 supposed to be generated forever.
2707 Set the number or the name of the test to perform. Supported tests are:
2722 Default value is "all", which will cycle through the list of all tests.
2725 For example the following:
2730 will generate a "dc_luma" test pattern.
2734 Provide a frei0r source.
2736 To enable compilation of this filter you need to install the frei0r
2737 header and configure FFmpeg with --enable-frei0r.
2739 The source supports the syntax:
2741 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
2744 @var{size} is the size of the video to generate, may be a string of the
2745 form @var{width}x@var{height} or a frame size abbreviation.
2746 @var{rate} is the rate of the video to generate, may be a string of
2747 the form @var{num}/@var{den} or a frame rate abbreviation.
2748 @var{src_name} is the name to the frei0r source to load. For more
2749 information regarding frei0r and how to set the parameters read the
2750 section @ref{frei0r} in the description of the video filters.
2752 Some examples follow:
2754 # generate a frei0r partik0l source with size 200x200 and framerate 10
2755 # which is overlayed on the overlay filter main input
2756 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
2759 @section nullsrc, rgbtestsrc, testsrc
2761 The @code{nullsrc} source returns unprocessed video frames. It is
2762 mainly useful to be employed in analysis / debugging tools, or as the
2763 source for filters which ignore the input data.
2765 The @code{rgbtestsrc} source generates an RGB test pattern useful for
2766 detecting RGB vs BGR issues. You should see a red, green and blue
2767 stripe from top to bottom.
2769 The @code{testsrc} source generates a test video pattern, showing a
2770 color pattern, a scrolling gradient and a timestamp. This is mainly
2771 intended for testing purposes.
2773 These sources accept an optional sequence of @var{key}=@var{value} pairs,
2774 separated by ":". The description of the accepted options follows.
2779 Specify the size of the sourced video, it may be a string of the form
2780 @var{width}x@var{heigth}, or the name of a size abbreviation. The
2781 default value is "320x240".
2784 Specify the frame rate of the sourced video, as the number of frames
2785 generated per second. It has to be a string in the format
2786 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
2787 number or a valid video frame rate abbreviation. The default value is
2791 Set the sample aspect ratio of the sourced video.
2794 Set the video duration of the sourced video. The accepted syntax is:
2796 [-]HH[:MM[:SS[.m...]]]
2799 See also the function @code{av_parse_time()}.
2801 If not specified, or the expressed duration is negative, the video is
2802 supposed to be generated forever.
2805 For example the following:
2807 testsrc=duration=5.3:size=qcif:rate=10
2810 will generate a video with a duration of 5.3 seconds, with size
2811 176x144 and a framerate of 10 frames per second.
2813 If the input content is to be ignored, @code{nullsrc} can be used. The
2814 following command generates noise in the luminance plane by employing
2815 the @code{mp=geq} filter:
2817 nullsrc=s=256x256, mp=geq=random(1)*255:128:128
2820 @c man end VIDEO SOURCES
2822 @chapter Video Sinks
2823 @c man begin VIDEO SINKS
2825 Below is a description of the currently available video sinks.
2829 Buffer video frames, and make them available to the end of the filter
2832 This sink is mainly intended for a programmatic use, in particular
2833 through the interface defined in @file{libavfilter/buffersink.h}.
2835 It does not require a string parameter in input, but you need to
2836 specify a pointer to a list of supported pixel formats terminated by
2837 -1 in the opaque parameter provided to @code{avfilter_init_filter}
2838 when initializing this sink.
2842 Null video sink, do absolutely nothing with the input video. It is
2843 mainly useful as a template and to be employed in analysis / debugging
2846 @c man end VIDEO SINKS