2 @c man begin AUDIO FILTERS
4 When you configure your FFmpeg build, you can disable any of the
5 existing filters using --disable-filters.
6 The configure output will show the audio filters included in your
9 Below is a description of the currently available audio filters.
13 Pass the audio source unchanged to the output.
15 @c man end AUDIO FILTERS
17 @chapter Audio Sources
18 @c man begin AUDIO SOURCES
20 Below is a description of the currently available audio sources.
24 Null audio source, never return audio frames. It is mainly useful as a
25 template and to be employed in analysis / debugging tools.
27 It accepts as optional parameter a string of the form
28 @var{sample_rate}:@var{channel_layout}.
30 @var{sample_rate} specify the sample rate, and defaults to 44100.
32 @var{channel_layout} specify the channel layout, and can be either an
33 integer or a string representing a channel layout. The default value
34 of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
36 Check the channel_layout_map definition in
37 @file{libavcodec/audioconvert.c} for the mapping between strings and
38 channel layout values.
42 # set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
49 @c man end AUDIO SOURCES
52 @c man begin AUDIO SINKS
54 Below is a description of the currently available audio sinks.
58 Null audio sink, do absolutely nothing with the input audio. It is
59 mainly useful as a template and to be employed in analysis / debugging
62 @c man end AUDIO SINKS
64 @chapter Video Filters
65 @c man begin VIDEO FILTERS
67 When you configure your FFmpeg build, you can disable any of the
68 existing filters using --disable-filters.
69 The configure output will show the video filters included in your
72 Below is a description of the currently available video filters.
76 Detect frames that are (almost) completely black. Can be useful to
77 detect chapter transitions or commercials. Output lines consist of
78 the frame number of the detected frame, the percentage of blackness,
79 the position in the file if known or -1 and the timestamp in seconds.
81 In order to display the output lines, you need to set the loglevel at
82 least to the AV_LOG_INFO value.
84 The filter accepts the syntax:
86 blackframe[=@var{amount}:[@var{threshold}]]
89 @var{amount} is the percentage of the pixels that have to be below the
90 threshold, and defaults to 98.
92 @var{threshold} is the threshold below which a pixel value is
93 considered black, and defaults to 32.
97 Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
99 The parameters are expressions containing the following constants:
103 the corresponding mathematical approximated values for e
104 (euler number), pi (greek PI), PHI (golden ratio)
107 the computed values for @var{x} and @var{y}. They are evaluated for
111 the input width and heigth
114 same as @var{in_w} and @var{in_h}
117 the output (cropped) width and heigth
120 same as @var{out_w} and @var{out_h}
123 the number of input frame, starting from 0
126 the position in the file of the input frame, NAN if unknown
129 timestamp expressed in seconds, NAN if the input timestamp is unknown
133 The @var{out_w} and @var{out_h} parameters specify the expressions for
134 the width and height of the output (cropped) video. They are
135 evaluated just at the configuration of the filter.
137 The default value of @var{out_w} is "in_w", and the default value of
138 @var{out_h} is "in_h".
140 The expression for @var{out_w} may depend on the value of @var{out_h},
141 and the expression for @var{out_h} may depend on @var{out_w}, but they
142 cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
143 evaluated after @var{out_w} and @var{out_h}.
145 The @var{x} and @var{y} parameters specify the expressions for the
146 position of the top-left corner of the output (non-cropped) area. They
147 are evaluated for each frame. If the evaluated value is not valid, it
148 is approximated to the nearest valid value.
150 The default value of @var{x} is "(in_w-out_w)/2", and the default
151 value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
152 the center of the input image.
154 The expression for @var{x} may depend on @var{y}, and the expression
155 for @var{y} may depend on @var{x}.
157 Follow some examples:
159 # crop the central input area with size 100x100
162 # crop the central input area with size 2/3 of the input video
163 "crop=2/3*in_w:2/3*in_h"
165 # crop the input video central square
168 # delimit the rectangle with the top-left corner placed at position
169 # 100:100 and the right-bottom corner corresponding to the right-bottom
170 # corner of the input image.
171 crop=in_w-100:in_h-100:100:100
173 # crop 10 pixels from the lefth and right borders, and 20 pixels from
174 # the top and bottom borders
175 "crop=in_w-2*10:in_h-2*20"
177 # keep only the bottom right quarter of the input image
178 "crop=in_w/2:in_h/2:in_w/2:in_h/2"
180 # crop height for getting Greek harmony
181 "crop=in_w:1/PHI*in_w"
184 "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)"
186 # erratic camera effect depending on timestamp and position
187 "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)"
189 # set x depending on the value of y
190 "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
195 Auto-detect crop size.
197 Calculate necessary cropping parameters and prints the recommended
198 parameters through the logging system. The detected dimensions
199 correspond to the non-black area of the input video.
201 It accepts the syntax:
203 cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
209 Threshold, which can be optionally specified from nothing (0) to
210 everything (255), defaults to 24.
213 Value which the width/height should be divisible by, defaults to
214 16. The offset is automatically adjusted to center the video. Use 2 to
215 get only even dimensions (needed for 4:2:2 video). 16 is best when
216 encoding to most video codecs.
219 Counter that determines after how many frames cropdetect will reset
220 the previously detected largest video area and start over to detect
221 the current optimal crop area. Defaults to 0.
223 This can be useful when channel logos distort the video area. 0
224 indicates never reset and return the largest area encountered during
230 Draw a colored box on the input image.
232 It accepts the syntax:
234 drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
240 Specify the top left corner coordinates of the box. Default to 0.
243 Specify the width and height of the box, if 0 they are interpreted as
244 the input width and height. Default to 0.
247 Specify the color of the box to write, it can be the name of a color
248 (case insensitive match) or a 0xRRGGBB[AA] sequence.
251 Follow some examples:
253 # draw a black box around the edge of the input image
256 # draw a box with color red and an opacity of 50%
257 drawbox=10:20:200:60:red@@0.5"
262 Buffer input images and send them when they are requested.
264 This filter is mainly useful when auto-inserted by the libavfilter
267 The filter does not take parameters.
271 Convert the input video to one of the specified pixel formats.
272 Libavfilter will try to pick one that is supported for the input to
275 The filter accepts a list of pixel format names, separated by ":",
276 for example "yuv420p:monow:rgb24".
278 The following command:
281 ./ffmpeg -i in.avi -vf "format=yuv420p" out.avi
284 will convert the input video to the format "yuv420p".
289 Apply a frei0r effect to the input video.
291 To enable compilation of this filter you need to install the frei0r
292 header and configure FFmpeg with --enable-frei0r.
294 The filter supports the syntax:
296 @var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
299 @var{filter_name} is the name to the frei0r effect to load. If the
300 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
301 is searched in each one of the directories specified by the colon
302 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
303 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
304 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
306 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
307 for the frei0r effect.
309 A frei0r effect parameter can be a boolean (whose values are specified
310 with "y" and "n"), a double, a color (specified by the syntax
311 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
312 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
313 description), a position (specified by the syntax @var{X}/@var{Y},
314 @var{X} and @var{Y} being float numbers) and a string.
316 The number and kind of parameters depend on the loaded effect. If an
317 effect parameter is not specified the default value is set.
319 Some examples follow:
321 # apply the distort0r effect, set the first two double parameters
322 frei0r=distort0r:0.5:0.01
324 # apply the colordistance effect, takes a color as first parameter
325 frei0r=colordistance:0.2/0.3/0.4
326 frei0r=colordistance:violet
327 frei0r=colordistance:0x112233
329 # apply the perspective effect, specify the top left and top right
331 frei0r=perspective:0.2/0.2:0.8/0.2
334 For more information see:
335 @url{http://piksel.org/frei0r}
339 Flip the input video horizontally.
341 For example to horizontally flip the video in input with
344 ffmpeg -i in.avi -vf "hflip" out.avi
349 High precision/quality 3d denoise filter. This filter aims to reduce
350 image noise producing smooth images and making still images really
351 still. It should enhance compressibility.
353 It accepts the following optional parameters:
354 @var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
358 a non-negative float number which specifies spatial luma strength,
362 a non-negative float number which specifies spatial chroma strength,
363 defaults to 3.0*@var{luma_spatial}/4.0
366 a float number which specifies luma temporal strength, defaults to
367 6.0*@var{luma_spatial}/4.0
370 a float number which specifies chroma temporal strength, defaults to
371 @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
376 Force libavfilter not to use any of the specified pixel formats for the
377 input to the next filter.
379 The filter accepts a list of pixel format names, separated by ":",
380 for example "yuv420p:monow:rgb24".
382 The following command:
385 ./ffmpeg -i in.avi -vf "noformat=yuv420p, vflip" out.avi
388 will make libavfilter use a format different from "yuv420p" for the
389 input to the vflip filter.
393 Pass the video source unchanged to the output.
397 Apply smooth transform using libopencv.
399 To enable this filter install libopencv library and headers and
400 configure FFmpeg with --enable-libopencv.
402 The filter accepts the following parameters:
403 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
405 @var{type} is the type of smooth filter to apply, and can be one of
406 the following values: "blur", "blur_no_scale", "median", "gaussian",
407 "bilateral". The default value is "gaussian".
409 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
410 parameters whose meanings depend on smooth type. @var{param1} and
411 @var{param2} accept integer positive values or 0, @var{param3} and
412 @var{param4} accept float values.
414 The default value for @var{param1} is 3, the default value for the
415 other parameters is 0.
417 These parameters correspond to the parameters assigned to the
418 libopencv function @code{cvSmooth}. Refer to the official libopencv
419 documentation for the exact meaning of the parameters:
420 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
424 Overlay one video on top of another.
426 It takes two inputs and one output, the first input is the "main"
427 video on which the second input is overlayed.
429 It accepts the parameters: @var{x}:@var{y}.
431 @var{x} is the x coordinate of the overlayed video on the main video,
432 @var{y} is the y coordinate. The parameters are expressions containing
433 the following parameters:
437 main input width and height
440 same as @var{main_w} and @var{main_h}
442 @item overlay_w, overlay_h
443 overlay input width and height
446 same as @var{overlay_w} and @var{overlay_h}
449 Be aware that frames are taken from each input video in timestamp
450 order, hence, if their initial timestamps differ, it is a a good idea
451 to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
452 have them begin in the same zero timestamp, as it does the example for
453 the @var{movie} filter.
455 Follow some examples:
457 # draw the overlay at 10 pixels from the bottom right
458 # corner of the main video.
459 overlay=main_w-overlay_w-10:main_h-overlay_h-10
461 # insert a transparent PNG logo in the bottom left corner of the input
462 movie=0:png:logo.png [logo];
463 [in][logo] overlay=10:main_h-overlay_h-10 [out]
465 # insert 2 different transparent PNG logos (second logo on bottom
467 movie=0:png:logo1.png [logo1];
468 movie=0:png:logo2.png [logo2];
469 [in][logo1] overlay=10:H-h-10 [in+logo1];
470 [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
472 # add a transparent color layer on top of the main video,
473 # WxH specifies the size of the main input to the overlay filter
474 color=red@.3:WxH [over]; [in][over] overlay [out]
477 You can chain togheter more overlays but the efficiency of such
478 approach is yet to be tested.
482 Add paddings to the input image, and places the original input at the
483 given coordinates @var{x}, @var{y}.
485 It accepts the following parameters:
486 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
488 Follows the description of the accepted parameters.
493 Specify the size of the output image with the paddings added. If the
494 value for @var{width} or @var{height} is 0, the corresponding input size
495 is used for the output.
497 The default value of @var{width} and @var{height} is 0.
501 Specify the offsets where to place the input image in the padded area
502 with respect to the top/left border of the output image.
504 The default value of @var{x} and @var{y} is 0.
508 Specify the color of the padded area, it can be the name of a color
509 (case insensitive match) or a 0xRRGGBB[AA] sequence.
511 The default value of @var{color} is "black".
518 # Add paddings with color "violet" to the input video. Output video
519 # size is 640x480, the top-left corner of the input video is placed at
521 pad=640:480:0:40:violet
526 Pixel format descriptor test filter, mainly useful for internal
527 testing. The output video should be equal to the input video.
531 format=monow, pixdesctest
534 can be used to test the monowhite pixel format descriptor definition.
538 Scale the input video to @var{width}:@var{height} and/or convert the image format.
540 For example the command:
543 ./ffmpeg -i in.avi -vf "scale=200:100" out.avi
546 will scale the input video to a size of 200x100.
548 If the input image format is different from the format requested by
549 the next filter, the scale filter will convert the input to the
552 If the value for @var{width} or @var{height} is 0, the respective input
553 size is used for the output.
555 If the value for @var{width} or @var{height} is -1, the scale filter will
556 use, for the respective output size, a value that maintains the aspect
557 ratio of the input image.
559 The default value of @var{width} and @var{height} is 0.
563 Change the PTS (presentation timestamp) of the input video frames.
565 Accept in input an expression evaluated through the eval API, which
566 can contain the following constants:
570 the presentation timestamp in input
582 the count of the input frame, starting from 0.
585 the PTS of the first video frame
588 tell if the current frame is interlaced
591 original position in the file of the frame, or undefined if undefined
592 for the current frame
602 Some examples follow:
605 # start counting PTS from zero
617 # fixed rate 25 fps with some jitter
618 setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
623 Set the timebase to use for the output frames timestamps.
624 It is mainly useful for testing timebase configuration.
626 It accepts in input an arithmetic expression representing a rational.
627 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
628 default timebase), and "intb" (the input timebase).
630 The default value for the input is "intb".
632 Follow some examples.
635 # set the timebase to 1/25
638 # set the timebase to 1/10
641 #set the timebase to 1001/1000
644 #set the timebase to 2*intb
647 #set the default timebase value
653 Pass the images of input video on to next video filter as multiple
657 ./ffmpeg -i in.avi -vf "slicify=32" out.avi
660 The filter accepts the slice height as parameter. If the parameter is
661 not specified it will use the default value of 16.
663 Adding this in the beginning of filter chains should make filtering
664 faster due to better use of the memory cache.
668 Transpose rows with columns in the input video and optionally flip it.
670 It accepts a parameter representing an integer, which can assume the
675 Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
683 Rotate by 90 degrees clockwise, that is:
691 Rotate by 90 degrees counterclockwise, that is:
699 Rotate by 90 degrees clockwise and vertically flip, that is:
709 Sharpen or blur the input video.
711 It accepts the following parameters:
712 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
714 Negative values for the amount will blur the input video, while positive
715 values will sharpen. All parameters are optional and default to the
716 equivalent of the string '5:5:1.0:0:0:0.0'.
721 Set the luma matrix horizontal size. It can be an integer between 3
722 and 13, default value is 5.
725 Set the luma matrix vertical size. It can be an integer between 3
726 and 13, default value is 5.
729 Set the luma effect strength. It can be a float number between -2.0
730 and 5.0, default value is 1.0.
733 Set the chroma matrix horizontal size. It can be an integer between 3
734 and 13, default value is 0.
737 Set the chroma matrix vertical size. It can be an integer between 3
738 and 13, default value is 0.
741 Set the chroma effect strength. It can be a float number between -2.0
742 and 5.0, default value is 0.0.
747 # Strong luma sharpen effect parameters
750 # Strong blur of both luma and chroma parameters
751 unsharp=7:7:-2:7:7:-2
753 # Use the default values with @command{ffmpeg}
754 ./ffmpeg -i in.avi -vf "unsharp" out.mp4
759 Flip the input video vertically.
762 ./ffmpeg -i in.avi -vf "vflip" out.avi
767 yadif is "yet another deinterlacing filter".
769 It accepts the syntax:
771 yadif=[@var{mode}[:@var{parity}]]
777 Specify the interlacing mode to adopt, accepts one of the following values.
779 0: Output 1 frame for each frame.
781 1: Output 1 frame for each field.
783 2: Like 0 but skips spatial interlacing check.
785 3: Like 1 but skips spatial interlacing check.
790 0 if is bottom field first, 1 if the interlaced video is top field
791 first, -1 to enable automatic detection.
795 @c man end VIDEO FILTERS
797 @chapter Video Sources
798 @c man begin VIDEO SOURCES
800 Below is a description of the currently available video sources.
804 Buffer video frames, and make them available to the filter chain.
806 This source is mainly intended for a programmatic use, in particular
807 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
809 It accepts the following parameters:
810 @var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}
812 All the parameters need to be explicitely defined.
814 Follows the list of the accepted parameters.
819 Specify the width and height of the buffered video frames.
822 A string representing the pixel format of the buffered video frames.
823 It may be a number corresponding to a pixel format, or a pixel format
826 @item timebase_num, timebase_den
827 Specify numerator and denomitor of the timebase assumed by the
828 timestamps of the buffered frames.
833 buffer=320:240:yuv410p:1:24
836 will instruct the source to accept video frames with size 320x240 and
837 with format "yuv410p" and assuming 1/24 as the timestamps timebase.
838 Since the pixel format with name "yuv410p" corresponds to the number 6
839 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
840 this example corresponds to:
842 buffer=320:240:6:1:24
847 Provide an uniformly colored input.
849 It accepts the following parameters:
850 @var{color}:@var{frame_size}:@var{frame_rate}
852 Follows the description of the accepted parameters.
857 Specify the color of the source. It can be the name of a color (case
858 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
859 alpha specifier. The default value is "black".
862 Specify the size of the sourced video, it may be a string of the form
863 @var{width}x@var{heigth}, or the name of a size abbreviation. The
864 default value is "320x240".
867 Specify the frame rate of the sourced video, as the number of frames
868 generated per second. It has to be a string in the format
869 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
870 number or a valid video frame rate abbreviation. The default value is
875 For example the following graph description will generate a red source
876 with an opacity of 0.2, with size "qcif" and a frame rate of 10
877 frames per second, which will be overlayed over the source connected
878 to the pad with identifier "in".
881 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
886 Null video source, never return images. It is mainly useful as a
887 template and to be employed in analysis / debugging tools.
889 It accepts as optional parameter a string of the form
890 @var{width}:@var{height}:@var{timebase}.
892 @var{width} and @var{height} specify the size of the configured
893 source. The default values of @var{width} and @var{height} are
894 respectively 352 and 288 (corresponding to the CIF size format).
896 @var{timebase} specifies an arithmetic expression representing a
897 timebase. The expression can contain the constants "PI", "E", "PHI",
898 "AVTB" (the default timebase), and defaults to the value "AVTB".
902 Provide a frei0r source.
904 To enable compilation of this filter you need to install the frei0r
905 header and configure FFmpeg with --enable-frei0r.
907 The source supports the syntax:
909 @var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
912 @var{size} is the size of the video to generate, may be a string of the
913 form @var{width}x@var{height} or a frame size abbreviation.
914 @var{rate} is the rate of the video to generate, may be a string of
915 the form @var{num}/@var{den} or a frame rate abbreviation.
916 @var{src_name} is the name to the frei0r source to load. For more
917 information regarding frei0r and how to set the parameters read the
918 section "frei0r" (@pxref{frei0r}) in the description of the video
921 Some examples follow:
923 # generate a frei0r partik0l source with size 200x200 and framerate 10
924 # which is overlayed on the overlay filter main input
925 frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
928 @c man end VIDEO SOURCES
931 @c man begin VIDEO SINKS
933 Below is a description of the currently available video sinks.
937 Null video sink, do absolutely nothing with the input video. It is
938 mainly useful as a template and to be employed in analysis / debugging
941 @c man end VIDEO SINKS