Statistics
| Branch: | Revision:

ffmpeg / doc / filters.texi @ f0a55438

History | View | Annotate | Download (15.6 KB)

1 f59e9eaf Stefano Sabatini
@chapter Audio Filters
2
@c man begin AUDIO FILTERS
3
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
7
build.
8
9
Below is a description of the currently available audio filters.
10
11 99046339 S.N. Hemanth Meenakshisundaram
@section anull
12
13
Pass the audio source unchanged to the output.
14
15 f59e9eaf Stefano Sabatini
@c man end AUDIO FILTERS
16
17 1ee410f3 Stefano Sabatini
@chapter Audio Sources
18
@c man begin AUDIO SOURCES
19
20
Below is a description of the currently available audio sources.
21
22
@section anullsrc
23
24
Null audio source, never return audio frames. It is mainly useful as a
25
template and to be employed in analysis / debugging tools.
26
27
It accepts as optional parameter a string of the form
28
@var{sample_rate}:@var{channel_layout}.
29
30
@var{sample_rate} specify the sample rate, and defaults to 44100.
31
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.
35
36
Check the channel_layout_map definition in
37
@file{libavcodec/audioconvert.c} for the correspondance between string
38
and channel layout values.
39
40
Follow some examples:
41
@example
42
#  set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
43
anullsrc=48000:4
44
45
# same as
46
anullsrc=48000:mono
47
@end example
48
49
@c man end AUDIO SOURCES
50
51 f0a55438 S.N. Hemanth Meenakshisundaram
@chapter Audio Sinks
52
@c man begin AUDIO SINKS
53
54
Below is a description of the currently available audio sinks.
55
56
@section anullsink
57
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
60
tools.
61
62
@c man end AUDIO SINKS
63
64 3275ac6a Stefano Sabatini
@chapter Video Filters
65
@c man begin VIDEO FILTERS
66
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
70
build.
71
72
Below is a description of the currently available video filters.
73
74
@section crop
75
76 75b67a8a Stefano Sabatini
Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
77 3275ac6a Stefano Sabatini
78 75b67a8a Stefano Sabatini
The parameters are expressions containing the following constants:
79
80
@table @option
81
@item E, PI, PHI
82
the corresponding mathematical approximated values for e
83
(euler number), pi (greek PI), PHI (golden ratio)
84
85
@item x, y
86
the computed values for @var{x} and @var{y}. They are evaluated for
87
each new frame.
88
89
@item in_w, in_h
90
the input width and heigth
91
92
@item iw, ih
93
same as @var{in_w} and @var{in_h}
94
95
@item out_w, out_h
96
the output (cropped) width and heigth
97
98
@item ow, oh
99
same as @var{out_w} and @var{out_h}
100
101
@item n
102
the number of input frame, starting from 0
103
104
@item pos
105
the position in the file of the input frame, NAN if unknown
106
107
@item t
108
timestamp expressed in seconds, NAN if the input timestamp is unknown
109 3275ac6a Stefano Sabatini
110 75b67a8a Stefano Sabatini
@end table
111 3275ac6a Stefano Sabatini
112 75b67a8a Stefano Sabatini
The @var{out_w} and @var{out_h} parameters specify the expressions for
113
the width and height of the output (cropped) video. They are
114
evaluated just at the configuration of the filter.
115 3275ac6a Stefano Sabatini
116 75b67a8a Stefano Sabatini
The default value of @var{out_w} is "in_w", and the default value of
117
@var{out_h} is "in_h".
118 2bc05d35 Stefano Sabatini
119 75b67a8a Stefano Sabatini
The expression for @var{out_w} may depend on the value of @var{out_h},
120
and the expression for @var{out_h} may depend on @var{out_w}, but they
121
cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
122
evaluated after @var{out_w} and @var{out_h}.
123 2bc05d35 Stefano Sabatini
124 75b67a8a Stefano Sabatini
The @var{x} and @var{y} parameters specify the expressions for the
125
position of the top-left corner of the output (non-cropped) area. They
126
are evaluated for each frame. If the evaluated value is not valid, it
127
is approximated to the nearest valid value.
128 3275ac6a Stefano Sabatini
129 75b67a8a Stefano Sabatini
The default value of @var{x} is "(in_w-out_w)/2", and the default
130
value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
131
the center of the input image.
132
133
The expression for @var{x} may depend on @var{y}, and the expression
134
for @var{y} may depend on @var{x}.
135
136
Follow some examples:
137 3275ac6a Stefano Sabatini
@example
138 75b67a8a Stefano Sabatini
# crop the central input area with size 100x100
139
crop=100:100
140
141
# crop the central input area with size 2/3 of the input video
142
"crop=2/3*in_w:2/3*in_h"
143
144
# crop the input video central square
145
crop=in_h
146
147
# delimit the rectangle with the top-left corner placed at position
148
# 100:100 and the right-bottom corner corresponding to the right-bottom
149
# corner of the input image.
150
crop=in_w-100:in_h-100:100:100
151 3275ac6a Stefano Sabatini
152 75b67a8a Stefano Sabatini
# crop 10 pixels from the lefth and right borders, and 20 pixels from
153
# the top and bottom borders
154
"crop=in_w-2*10:in_h-2*20"
155 3275ac6a Stefano Sabatini
156 75b67a8a Stefano Sabatini
# keep only the bottom right quarter of the input image
157
"crop=in_w/2:in_h/2:in_w/2:in_h/2"
158
159
# crop height for getting Greek harmony
160
"crop=in_w:1/PHI*in_w"
161
162
# trembling effect
163
"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)"
164
165
# erratic camera effect depending on timestamp and position
166
"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)"
167
168
# set x depending on the value of y
169
"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
170
@end example
171 3275ac6a Stefano Sabatini
172 7f1af825 Stefano Sabatini
@section fifo
173
174
Buffer input images and send them when they are requested.
175
176
This filter is mainly useful when auto-inserted by the libavfilter
177
framework.
178
179
The filter does not take parameters.
180
181 3275ac6a Stefano Sabatini
@section format
182
183
Convert the input video to one of the specified pixel formats.
184
Libavfilter will try to pick one that is supported for the input to
185
the next filter.
186
187 b1094275 Stefano Sabatini
The filter accepts a list of pixel format names, separated by ":",
188
for example "yuv420p:monow:rgb24".
189 3275ac6a Stefano Sabatini
190
The following command:
191
192
@example
193
./ffmpeg -i in.avi -vf "format=yuv420p" out.avi
194
@end example
195
196 b1094275 Stefano Sabatini
will convert the input video to the format "yuv420p".
197 3275ac6a Stefano Sabatini
198 47941088 Stefano Sabatini
@section frei0r
199
200
Apply a frei0r effect to the input video.
201
202
To enable compilation of this filter you need to install the frei0r
203
header and configure FFmpeg with --enable-frei0r.
204
205
The filter supports the syntax:
206
@example
207
@var{filter_name}:@var{param1}:@var{param2}:...:@var{paramN}
208
@end example
209
210
@var{filter_name} is the name to the frei0r effect to load. If the
211
environment variable @env{FREI0R_PATH} is defined, the frei0r effect
212
is searched in each one of the directories specified by the colon
213
separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
214
paths, which are in this order: @file{HOME/.frei0r-1/lib/},
215
@file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
216
217
@var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
218
for the frei0r effect.
219
220
A frei0r effect parameter can be a boolean (whose values are specified
221
with "y" and "n"), a double, a color (specified by the syntax
222
@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
223
numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
224
description), a position (specified by the syntax @var{X}/@var{Y},
225
@var{X} and @var{Y} being float numbers) and a string.
226
227
The number and kind of parameters depend on the loaded effect. If an
228
effect parameter is not specified the default value is set.
229
230
Some examples follow:
231
@example
232
# apply the distort0r effect, set the first two double parameters
233
frei0r=distort0r:0.5:0.01
234
235
# apply the colordistance effect, takes a color as first parameter
236
frei0r=colordistance:0.2/0.3/0.4
237
frei0r=colordistance:violet
238
frei0r=colordistance:0x112233
239
240
# apply the perspective effect, specify the top left and top right
241
# image positions
242
frei0r=perspective:0.2/0.2:0.8/0.2
243
@end example
244
245
For more information see:
246
@url{http://piksel.org/frei0r}
247
248 a1e171df Stefano Sabatini
@section hflip
249
250
Flip the input video horizontally.
251
252
For example to horizontally flip the video in input with
253
@file{ffmpeg}:
254
@example
255
ffmpeg -i in.avi -vf "hflip" out.avi
256
@end example
257
258 3275ac6a Stefano Sabatini
@section noformat
259
260
Force libavfilter not to use any of the specified pixel formats for the
261
input to the next filter.
262
263 b1094275 Stefano Sabatini
The filter accepts a list of pixel format names, separated by ":",
264
for example "yuv420p:monow:rgb24".
265 3275ac6a Stefano Sabatini
266
The following command:
267
268
@example
269
./ffmpeg -i in.avi -vf "noformat=yuv420p, vflip" out.avi
270
@end example
271
272 b1094275 Stefano Sabatini
will make libavfilter use a format different from "yuv420p" for the
273 3275ac6a Stefano Sabatini
input to the vflip filter.
274
275
@section null
276
277 99046339 S.N. Hemanth Meenakshisundaram
Pass the video source unchanged to the output.
278 3275ac6a Stefano Sabatini
279 6ebf0bfc Stefano Sabatini
@section ocv_smooth
280
281
Apply smooth transform using libopencv.
282
283
To enable this filter install libopencv library and headers and
284
configure FFmpeg with --enable-libopencv.
285
286 58d94364 Stefano Sabatini
The filter accepts the following parameters:
287 6ebf0bfc Stefano Sabatini
@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
288
289
@var{type} is the type of smooth filter to apply, and can be one of
290 58d94364 Stefano Sabatini
the following values: "blur", "blur_no_scale", "median", "gaussian",
291 6ebf0bfc Stefano Sabatini
"bilateral". The default value is "gaussian".
292
293
@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
294
parameters whose meanings depend on smooth type. @var{param1} and
295
@var{param2} accept integer positive values or 0, @var{param3} and
296
@var{param4} accept float values.
297
298
The default value for @var{param1} is 3, the default value for the
299
other parameters is 0.
300
301 58d94364 Stefano Sabatini
These parameters correspond to the parameters assigned to the
302
libopencv function @code{cvSmooth}. Refer to the official libopencv
303 6ebf0bfc Stefano Sabatini
documentation for the exact meaning of the parameters:
304
@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
305
306 3275ac6a Stefano Sabatini
@section pad
307
308
Add paddings to the input image, and places the original input at the
309
given coordinates @var{x}, @var{y}.
310
311
It accepts the following parameters:
312
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
313
314
Follows the description of the accepted parameters.
315
316
@table @option
317
@item width, height
318
319
Specify the size of the output image with the paddings added. If the
320
value for @var{width} or @var{height} is 0, the corresponding input size
321
is used for the output.
322
323
The default value of @var{width} and @var{height} is 0.
324
325
@item x, y
326
327
Specify the offsets where to place the input image in the padded area
328
with respect to the top/left border of the output image.
329
330
The default value of @var{x} and @var{y} is 0.
331
332
@item color
333
334
Specify the color of the padded area, it can be the name of a color
335
(case insensitive match) or a 0xRRGGBB[AA] sequence.
336
337 b1094275 Stefano Sabatini
The default value of @var{color} is "black".
338 3275ac6a Stefano Sabatini
339
@end table
340
341 ce2e4ae3 Stefano Sabatini
@section pixdesctest
342
343
Pixel format descriptor test filter, mainly useful for internal
344
testing. The output video should be equal to the input video.
345
346
For example:
347
@example
348
format=monow, pixdesctest
349
@end example
350
351
can be used to test the monowhite pixel format descriptor definition.
352
353 3275ac6a Stefano Sabatini
@section scale
354
355
Scale the input video to @var{width}:@var{height} and/or convert the image format.
356
357
For example the command:
358
359
@example
360
./ffmpeg -i in.avi -vf "scale=200:100" out.avi
361
@end example
362
363
will scale the input video to a size of 200x100.
364
365
If the input image format is different from the format requested by
366
the next filter, the scale filter will convert the input to the
367
requested format.
368
369
If the value for @var{width} or @var{height} is 0, the respective input
370
size is used for the output.
371
372
If the value for @var{width} or @var{height} is -1, the scale filter will
373
use, for the respective output size, a value that maintains the aspect
374
ratio of the input image.
375
376
The default value of @var{width} and @var{height} is 0.
377
378
@section slicify
379
380
Pass the images of input video on to next video filter as multiple
381
slices.
382
383
@example
384
./ffmpeg -i in.avi -vf "slicify=32" out.avi
385
@end example
386
387
The filter accepts the slice height as parameter. If the parameter is
388
not specified it will use the default value of 16.
389
390
Adding this in the beginning of filter chains should make filtering
391
faster due to better use of the memory cache.
392
393
@section unsharp
394
395 843b5fd0 Stefano Sabatini
Sharpen or blur the input video.
396
397
It accepts the following parameters:
398
@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
399 3275ac6a Stefano Sabatini
400
Negative values for the amount will blur the input video, while positive
401
values will sharpen. All parameters are optional and default to the
402
equivalent of the string '5:5:1.0:0:0:0.0'.
403
404
@table @option
405
406
@item luma_msize_x
407
Set the luma matrix horizontal size. It can be an integer between 3
408
and 13, default value is 5.
409
410
@item luma_msize_y
411
Set the luma matrix vertical size. It can be an integer between 3
412
and 13, default value is 5.
413
414
@item luma_amount
415
Set the luma effect strength. It can be a float number between -2.0
416
and 5.0, default value is 1.0.
417
418
@item chroma_msize_x
419
Set the chroma matrix horizontal size. It can be an integer between 3
420
and 13, default value is 0.
421
422
@item chroma_msize_y
423
Set the chroma matrix vertical size. It can be an integer between 3
424
and 13, default value is 0.
425
426
@item luma_amount
427
Set the chroma effect strength. It can be a float number between -2.0
428
and 5.0, default value is 0.0.
429
430
@end table
431
432
@example
433
# Strong luma sharpen effect parameters
434
unsharp=7:7:2.5
435
436
# Strong blur of both luma and chroma parameters
437
unsharp=7:7:-2:7:7:-2
438
439
# Use the default values with @command{ffmpeg}
440
./ffmpeg -i in.avi -vf "unsharp" out.mp4
441
@end example
442
443
@section vflip
444
445
Flip the input video vertically.
446
447
@example
448
./ffmpeg -i in.avi -vf "vflip" out.avi
449
@end example
450
451
@c man end VIDEO FILTERS
452
453
@chapter Video Sources
454
@c man begin VIDEO SOURCES
455
456
Below is a description of the currently available video sources.
457
458 24413399 Stefano Sabatini
@section buffer
459
460
Buffer video frames, and make them available to the filter chain.
461
462
This source is mainly intended for a programmatic use, in particular
463 ac1a31ab VĂ­ctor Paesa
through the interface defined in @file{libavfilter/vsrc_buffer.h}.
464 24413399 Stefano Sabatini
465
It accepts the following parameters:
466
@var{width}:@var{height}:@var{pix_fmt_string}
467
468
All the parameters need to be explicitely defined.
469
470
Follows the list of the accepted parameters.
471
472
@table @option
473
474
@item width, height
475
Specify the width and height of the buffered video frames.
476
477
@item pix_fmt_string
478
479
A string representing the pixel format of the buffered video frames.
480
It may be a number corresponding to a pixel format, or a pixel format
481
name.
482
483
@end table
484
485
For example:
486
@example
487
buffer=320:240:yuv410p
488
@end example
489
490
will instruct the source to accept video frames with size 320x240 and
491
with format "yuv410p". Since the pixel format with name "yuv410p"
492
corresponds to the number 6 (check the enum PixelFormat definition in
493
@file{libavutil/pixfmt.h}), this example corresponds to:
494
@example
495
buffer=320:240:6
496
@end example
497
498 23ccf3c7 Stefano Sabatini
@section color
499
500
Provide an uniformly colored input.
501
502
It accepts the following parameters:
503 b5f47309 Stefano Sabatini
@var{color}:@var{frame_size}:@var{frame_rate}
504 23ccf3c7 Stefano Sabatini
505
Follows the description of the accepted parameters.
506
507
@table @option
508
509
@item color
510
Specify the color of the source. It can be the name of a color (case
511
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
512
alpha specifier. The default value is "black".
513
514
@item frame_size
515
Specify the size of the sourced video, it may be a string of the form
516
@var{width}x@var{heigth}, or the name of a size abbreviation. The
517
default value is "320x240".
518
519
@item frame_rate
520
Specify the frame rate of the sourced video, as the number of frames
521
generated per second. It has to be a string in the format
522
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
523
number or a valid video frame rate abbreviation. The default value is
524
"25".
525
526
@end table
527
528
For example the following graph description will generate a red source
529
with an opacity of 0.2, with size "qcif" and a frame rate of 10
530
frames per second, which will be overlayed over the source connected
531
to the pad with identifier "in".
532
533
@example
534
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
535
@end example
536
537 3275ac6a Stefano Sabatini
@section nullsrc
538
539
Null video source, never return images. It is mainly useful as a
540
template and to be employed in analysis / debugging tools.
541
542
It accepts as optional parameter a string of the form
543
@var{width}:@var{height}, where @var{width} and @var{height} specify the size of
544
the configured source.
545
546
The default values of @var{width} and @var{height} are respectively 352
547
and 288 (corresponding to the CIF size format).
548
549
@c man end VIDEO SOURCES
550
551
@chapter Video Sinks
552
@c man begin VIDEO SINKS
553
554
Below is a description of the currently available video sinks.
555
556
@section nullsink
557
558
Null video sink, do absolutely nothing with the input video. It is
559
mainly useful as a template and to be employed in analysis / debugging
560
tools.
561
562
@c man end VIDEO SINKS