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".
288 Apply a frei0r effect to the input video.
290 To enable compilation of this filter you need to install the frei0r
291 header and configure FFmpeg with --enable-frei0r.
293 The filter supports the syntax:
295 @var{filter_name}:@var{param1}:@var{param2}:...:@var{paramN}
298 @var{filter_name} is the name to the frei0r effect to load. If the
299 environment variable @env{FREI0R_PATH} is defined, the frei0r effect
300 is searched in each one of the directories specified by the colon
301 separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
302 paths, which are in this order: @file{HOME/.frei0r-1/lib/},
303 @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
305 @var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
306 for the frei0r effect.
308 A frei0r effect parameter can be a boolean (whose values are specified
309 with "y" and "n"), a double, a color (specified by the syntax
310 @var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
311 numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
312 description), a position (specified by the syntax @var{X}/@var{Y},
313 @var{X} and @var{Y} being float numbers) and a string.
315 The number and kind of parameters depend on the loaded effect. If an
316 effect parameter is not specified the default value is set.
318 Some examples follow:
320 # apply the distort0r effect, set the first two double parameters
321 frei0r=distort0r:0.5:0.01
323 # apply the colordistance effect, takes a color as first parameter
324 frei0r=colordistance:0.2/0.3/0.4
325 frei0r=colordistance:violet
326 frei0r=colordistance:0x112233
328 # apply the perspective effect, specify the top left and top right
330 frei0r=perspective:0.2/0.2:0.8/0.2
333 For more information see:
334 @url{http://piksel.org/frei0r}
338 Flip the input video horizontally.
340 For example to horizontally flip the video in input with
343 ffmpeg -i in.avi -vf "hflip" out.avi
348 Force libavfilter not to use any of the specified pixel formats for the
349 input to the next filter.
351 The filter accepts a list of pixel format names, separated by ":",
352 for example "yuv420p:monow:rgb24".
354 The following command:
357 ./ffmpeg -i in.avi -vf "noformat=yuv420p, vflip" out.avi
360 will make libavfilter use a format different from "yuv420p" for the
361 input to the vflip filter.
365 Pass the video source unchanged to the output.
369 Apply smooth transform using libopencv.
371 To enable this filter install libopencv library and headers and
372 configure FFmpeg with --enable-libopencv.
374 The filter accepts the following parameters:
375 @var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
377 @var{type} is the type of smooth filter to apply, and can be one of
378 the following values: "blur", "blur_no_scale", "median", "gaussian",
379 "bilateral". The default value is "gaussian".
381 @var{param1}, @var{param2}, @var{param3}, and @var{param4} are
382 parameters whose meanings depend on smooth type. @var{param1} and
383 @var{param2} accept integer positive values or 0, @var{param3} and
384 @var{param4} accept float values.
386 The default value for @var{param1} is 3, the default value for the
387 other parameters is 0.
389 These parameters correspond to the parameters assigned to the
390 libopencv function @code{cvSmooth}. Refer to the official libopencv
391 documentation for the exact meaning of the parameters:
392 @url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
396 Add paddings to the input image, and places the original input at the
397 given coordinates @var{x}, @var{y}.
399 It accepts the following parameters:
400 @var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
402 Follows the description of the accepted parameters.
407 Specify the size of the output image with the paddings added. If the
408 value for @var{width} or @var{height} is 0, the corresponding input size
409 is used for the output.
411 The default value of @var{width} and @var{height} is 0.
415 Specify the offsets where to place the input image in the padded area
416 with respect to the top/left border of the output image.
418 The default value of @var{x} and @var{y} is 0.
422 Specify the color of the padded area, it can be the name of a color
423 (case insensitive match) or a 0xRRGGBB[AA] sequence.
425 The default value of @var{color} is "black".
431 Pixel format descriptor test filter, mainly useful for internal
432 testing. The output video should be equal to the input video.
436 format=monow, pixdesctest
439 can be used to test the monowhite pixel format descriptor definition.
443 Scale the input video to @var{width}:@var{height} and/or convert the image format.
445 For example the command:
448 ./ffmpeg -i in.avi -vf "scale=200:100" out.avi
451 will scale the input video to a size of 200x100.
453 If the input image format is different from the format requested by
454 the next filter, the scale filter will convert the input to the
457 If the value for @var{width} or @var{height} is 0, the respective input
458 size is used for the output.
460 If the value for @var{width} or @var{height} is -1, the scale filter will
461 use, for the respective output size, a value that maintains the aspect
462 ratio of the input image.
464 The default value of @var{width} and @var{height} is 0.
468 Set the timebase to use for the output frames timestamps.
469 It is mainly useful for testing timebase configuration.
471 It accepts in input an arithmetic expression representing a rational.
472 The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
473 default timebase), and "intb" (the input timebase).
475 The default value for the input is "intb".
477 Follow some examples.
480 # set the timebase to 1/25
483 # set the timebase to 1/10
486 #set the timebase to 1001/1000
489 #set the timebase to 2*intb
492 #set the default timebase value
498 Pass the images of input video on to next video filter as multiple
502 ./ffmpeg -i in.avi -vf "slicify=32" out.avi
505 The filter accepts the slice height as parameter. If the parameter is
506 not specified it will use the default value of 16.
508 Adding this in the beginning of filter chains should make filtering
509 faster due to better use of the memory cache.
513 Sharpen or blur the input video.
515 It accepts the following parameters:
516 @var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
518 Negative values for the amount will blur the input video, while positive
519 values will sharpen. All parameters are optional and default to the
520 equivalent of the string '5:5:1.0:0:0:0.0'.
525 Set the luma matrix horizontal size. It can be an integer between 3
526 and 13, default value is 5.
529 Set the luma matrix vertical size. It can be an integer between 3
530 and 13, default value is 5.
533 Set the luma effect strength. It can be a float number between -2.0
534 and 5.0, default value is 1.0.
537 Set the chroma matrix horizontal size. It can be an integer between 3
538 and 13, default value is 0.
541 Set the chroma matrix vertical size. It can be an integer between 3
542 and 13, default value is 0.
545 Set the chroma effect strength. It can be a float number between -2.0
546 and 5.0, default value is 0.0.
551 # Strong luma sharpen effect parameters
554 # Strong blur of both luma and chroma parameters
555 unsharp=7:7:-2:7:7:-2
557 # Use the default values with @command{ffmpeg}
558 ./ffmpeg -i in.avi -vf "unsharp" out.mp4
563 Flip the input video vertically.
566 ./ffmpeg -i in.avi -vf "vflip" out.avi
571 yadif is "yet another deinterlacing filter".
573 It accepts the syntax:
575 yadif=[@var{mode}[:@var{parity}]]
581 Specify the interlacing mode to adopt, accepts one of the following values.
583 0: Output 1 frame for each frame.
585 1: Output 1 frame for each field.
587 2: Like 0 but skips spatial interlacing check.
589 3: Like 1 but skips spatial interlacing check.
594 0 if is bottom field first, 1 if the interlaced video is top field
595 first, -1 to enable automatic detection.
599 @c man end VIDEO FILTERS
601 @chapter Video Sources
602 @c man begin VIDEO SOURCES
604 Below is a description of the currently available video sources.
608 Buffer video frames, and make them available to the filter chain.
610 This source is mainly intended for a programmatic use, in particular
611 through the interface defined in @file{libavfilter/vsrc_buffer.h}.
613 It accepts the following parameters:
614 @var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}
616 All the parameters need to be explicitely defined.
618 Follows the list of the accepted parameters.
623 Specify the width and height of the buffered video frames.
626 A string representing the pixel format of the buffered video frames.
627 It may be a number corresponding to a pixel format, or a pixel format
630 @item timebase_num, timebase_den
631 Specify numerator and denomitor of the timebase assumed by the
632 timestamps of the buffered frames.
637 buffer=320:240:yuv410p:1:24
640 will instruct the source to accept video frames with size 320x240 and
641 with format "yuv410p" and assuming 1/24 as the timestamps timebase.
642 Since the pixel format with name "yuv410p" corresponds to the number 6
643 (check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
644 this example corresponds to:
646 buffer=320:240:6:1:24
651 Provide an uniformly colored input.
653 It accepts the following parameters:
654 @var{color}:@var{frame_size}:@var{frame_rate}
656 Follows the description of the accepted parameters.
661 Specify the color of the source. It can be the name of a color (case
662 insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
663 alpha specifier. The default value is "black".
666 Specify the size of the sourced video, it may be a string of the form
667 @var{width}x@var{heigth}, or the name of a size abbreviation. The
668 default value is "320x240".
671 Specify the frame rate of the sourced video, as the number of frames
672 generated per second. It has to be a string in the format
673 @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
674 number or a valid video frame rate abbreviation. The default value is
679 For example the following graph description will generate a red source
680 with an opacity of 0.2, with size "qcif" and a frame rate of 10
681 frames per second, which will be overlayed over the source connected
682 to the pad with identifier "in".
685 "color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
690 Null video source, never return images. It is mainly useful as a
691 template and to be employed in analysis / debugging tools.
693 It accepts as optional parameter a string of the form
694 @var{width}:@var{height}:@var{timebase}.
696 @var{width} and @var{height} specify the size of the configured
697 source. The default values of @var{width} and @var{height} are
698 respectively 352 and 288 (corresponding to the CIF size format).
700 @var{timebase} specifies an arithmetic expression representing a
701 timebase. The expression can contain the constants "PI", "E", "PHI",
702 "AVTB" (the default timebase), and defaults to the value "AVTB".
704 @c man end VIDEO SOURCES
707 @c man begin VIDEO SINKS
709 Below is a description of the currently available video sinks.
713 Null video sink, do absolutely nothing with the input video. It is
714 mainly useful as a template and to be employed in analysis / debugging
717 @c man end VIDEO SINKS