ffmpeg.texi 58.3 KB
Newer Older
1 2
\input texinfo @c -*- texinfo -*-

3
@settitle ffmpeg Documentation
4
@titlepage
5
@center @titlefont{ffmpeg Documentation}
6 7
@end titlepage

8 9 10 11
@top

@contents

12 13
@chapter Synopsis

14
ffmpeg [@var{global_options}] @{[@var{input_file_options}] -i @file{input_file}@} ... @{[@var{output_file_options}] @file{output_file}@} ...
15

16 17
@chapter Description
@c man begin DESCRIPTION
18

19
@command{ffmpeg} is a very fast video and audio converter that can also grab from
20 21
a live audio/video source. It can also convert between arbitrary sample
rates and resize video on the fly with a high quality polyphase filter.
22

23
@command{ffmpeg} reads from an arbitrary number of input "files" (which can be regular
Michael Niedermayer's avatar
Michael Niedermayer committed
24 25
files, pipes, network streams, grabbing devices, etc.), specified by the
@code{-i} option, and writes to an arbitrary number of output "files", which are
Michael Niedermayer's avatar
Michael Niedermayer committed
26
specified by a plain output filename. Anything found on the command line which
Michael Niedermayer's avatar
Michael Niedermayer committed
27 28
cannot be interpreted as an option is considered to be an output filename.

29 30 31 32 33
Each input or output file can, in principle, contain any number of streams of
different types (video/audio/subtitle/attachment/data). The allowed number and/or
types of streams may be limited by the container format. Selecting which
streams from which inputs will go into which output is either done automatically
or with the @code{-map} option (see the Stream selection chapter).
Michael Niedermayer's avatar
Michael Niedermayer committed
34 35

To refer to input files in options, you must use their indices (0-based). E.g.
36
the first input file is @code{0}, the second is @code{1}, etc. Similarly, streams
Michael Niedermayer's avatar
Michael Niedermayer committed
37
within a file are referred to by their indices. E.g. @code{2:3} refers to the
38
fourth stream in the third input file. Also see the Stream specifiers chapter.
Michael Niedermayer's avatar
Michael Niedermayer committed
39

40 41 42 43
As a general rule, options are applied to the next specified
file. Therefore, order is important, and you can have the same
option on the command line multiple times. Each occurrence is
then applied to the next input or output file.
44 45
Exceptions from this rule are the global options (e.g. verbosity level),
which should be specified first.
46

Michael Niedermayer's avatar
Michael Niedermayer committed
47 48 49 50
Do not mix input and output files -- first specify all input files, then all
output files. Also do not mix options which belong to different files. All
options apply ONLY to the next input or output file and are reset between files.

51 52
@itemize
@item
53
To set the video bitrate of the output file to 64 kbit/s:
54
@example
rogerdpack's avatar
rogerdpack committed
55
ffmpeg -i input.avi -b:v 64k -bufsize 64k output.avi
56 57
@end example

58 59
@item
To force the frame rate of the output file to 24 fps:
60 61 62 63
@example
ffmpeg -i input.avi -r 24 output.avi
@end example

64 65
@item
To force the frame rate of the input file (valid for raw formats only)
66 67 68 69
to 1 fps and the frame rate of the output file to 24 fps:
@example
ffmpeg -r 1 -i input.m2v -r 24 output.avi
@end example
70
@end itemize
71 72 73 74 75

The format option may be needed for raw input files.

@c man end DESCRIPTION

76 77 78
@chapter Detailed description
@c man begin DETAILED DESCRIPTION

79
The transcoding process in @command{ffmpeg} for each output can be described by
80 81 82
the following diagram:

@example
83 84 85 86 87 88 89 90 91 92
 _______              ______________
|       |            |              |
| input |  demuxer   | encoded data |   decoder
| file  | ---------> | packets      | -----+
|_______|            |______________|      |
                                           v
                                       _________
                                      |         |
                                      | decoded |
                                      | frames  |
93 94
                                      |_________|
 ________             ______________       |
95 96 97 98 99
|        |           |              |      |
| output | <-------- | encoded data | <----+
| file   |   muxer   | packets      |   encoder
|________|           |______________|

100 101 102

@end example

103
@command{ffmpeg} calls the libavformat library (containing demuxers) to read
104
input files and get packets containing encoded data from them. When there are
105
multiple input files, @command{ffmpeg} tries to keep them synchronized by
106 107 108 109 110
tracking lowest timestamp on any active input stream.

Encoded packets are then passed to the decoder (unless streamcopy is selected
for the stream, see further for a description). The decoder produces
uncompressed frames (raw video/PCM audio/...) which can be processed further by
111 112
filtering (see next section). After filtering, the frames are passed to the
encoder, which encodes them and outputs encoded packets. Finally those are
113 114 115
passed to the muxer, which writes the encoded packets to the output file.

@section Filtering
116
Before encoding, @command{ffmpeg} can process raw audio and video frames using
117
filters from the libavfilter library. Several chained filters form a filter
118
graph. @command{ffmpeg} distinguishes between two types of filtergraphs:
119 120 121 122 123 124 125 126
simple and complex.

@subsection Simple filtergraphs
Simple filtergraphs are those that have exactly one input and output, both of
the same type. In the above diagram they can be represented by simply inserting
an additional step between decoding and encoding:

@example
127 128 129
 _________                        ______________
|         |                      |              |
| decoded |                      | encoded data |
130 131
| frames  |\                   _ | packets      |
|_________| \                  /||______________|
132
             \   __________   /
133 134
  simple     _\||          | /  encoder
  filtergraph   | filtered |/
135 136
                | frames   |
                |__________|
137 138 139 140 141 142 143 144

@end example

Simple filtergraphs are configured with the per-stream @option{-filter} option
(with @option{-vf} and @option{-af} aliases for video and audio respectively).
A simple filtergraph for video can look for example like this:

@example
145 146 147 148
 _______        _____________        _______        ________
|       |      |             |      |       |      |        |
| input | ---> | deinterlace | ---> | scale | ---> | output |
|_______|      |_____________|      |_______|      |________|
149 150 151 152 153 154 155 156 157 158

@end example

Note that some filters change frame properties but not frame contents. E.g. the
@code{fps} filter in the example above changes number of frames, but does not
touch the frame contents. Another example is the @code{setpts} filter, which
only sets timestamps and otherwise passes the frames unchanged.

@subsection Complex filtergraphs
Complex filtergraphs are those which cannot be described as simply a linear
159
processing chain applied to one stream. This is the case, for example, when the graph has
160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183
more than one input and/or output, or when output stream type is different from
input. They can be represented with the following diagram:

@example
 _________
|         |
| input 0 |\                    __________
|_________| \                  |          |
             \   _________    /| output 0 |
              \ |         |  / |__________|
 _________     \| complex | /
|         |     |         |/
| input 1 |---->| filter  |\
|_________|     |         | \   __________
               /| graph   |  \ |          |
              / |         |   \| output 1 |
 _________   /  |_________|    |__________|
|         | /
| input 2 |/
|_________|

@end example

Complex filtergraphs are configured with the @option{-filter_complex} option.
184
Note that this option is global, since a complex filtergraph, by its nature,
185 186
cannot be unambiguously associated with a single stream or file.

187 188
The @option{-lavfi} option is equivalent to @option{-filter_complex}.

189 190 191 192 193 194
A trivial example of a complex filtergraph is the @code{overlay} filter, which
has two video inputs and one video output, containing one video overlaid on top
of the other. Its audio counterpart is the @code{amix} filter.

@section Stream copy
Stream copy is a mode selected by supplying the @code{copy} parameter to the
195
@option{-codec} option. It makes @command{ffmpeg} omit the decoding and encoding
196 197
step for the specified stream, so it does only demuxing and muxing. It is useful
for changing the container format or modifying container-level metadata. The
198
diagram above will, in this case, simplify to this:
199 200 201 202 203 204 205 206 207 208 209

@example
 _______              ______________            ________
|       |            |              |          |        |
| input |  demuxer   | encoded data |  muxer   | output |
| file  | ---------> | packets      | -------> | file   |
|_______|            |______________|          |________|

@end example

Since there is no decoding or encoding, it is very fast and there is no quality
210
loss. However, it might not work in some cases because of many factors. Applying
211 212 213 214
filters is obviously also impossible, since filters work on uncompressed data.

@c man end DETAILED DESCRIPTION

215 216 217
@chapter Stream selection
@c man begin STREAM SELECTION

218
By default, @command{ffmpeg} includes only one stream of each type (video, audio, subtitle)
219
present in the input files and adds them to each output file.  It picks the
220 221 222 223
"best" of each based upon the following criteria: for video, it is the stream
with the highest resolution, for audio, it is the stream with the most channels, for
subtitles, it is the first subtitle stream. In the case where several streams of
the same type rate equally, the stream with the lowest index is chosen.
224

225
You can disable some of those defaults by using the @code{-vn/-an/-sn} options. For
226 227 228 229 230
full manual control, use the @code{-map} option, which disables the defaults just
described.

@c man end STREAM SELECTION

231
@chapter Options
232
@c man begin OPTIONS
233

234
@include fftools-common-opts.texi
235

236 237
@section Main options

238
@table @option
239

240
@item -f @var{fmt} (@emph{input/output})
241
Force input or output file format. The format is normally auto detected for input
242
files and guessed from the file extension for output files, so this option is not
243
needed in most cases.
Fabrice Bellard's avatar
Fabrice Bellard committed
244

245
@item -i @var{filename} (@emph{input})
246
input file name
247

248
@item -y (@emph{global})
249
Overwrite output files without asking.
250

251
@item -n (@emph{global})
252 253
Do not overwrite output files, and exit immediately if a specified
output file already exists.
254

255 256 257 258 259
@item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
@itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
Select an encoder (when used before an output file) or a decoder (when used
before an input file) for one or more streams. @var{codec} is the name of a
decoder/encoder or a special value @code{copy} (output only) to indicate that
260
the stream is not to be re-encoded.
261 262 263 264 265 266 267 268 269 270 271 272 273 274

For example
@example
ffmpeg -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
@end example
encodes all video streams with libx264 and copies all audio streams.

For each stream, the last matching @code{c} option is applied, so
@example
ffmpeg -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
@end example
will copy all the streams except the second video, which will be encoded with
libx264, and the 138th audio, which will be encoded with libvorbis.

275 276 277 278 279 280 281
@item -t @var{duration} (@emph{input/output})
When used as an input option (before @code{-i}), limit the @var{duration} of
data read from the input file.

When used as an output option (before an output filename), stop writing the
output after its duration reaches @var{duration}.

282
@var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
283

284 285 286 287 288 289 290 291
-to and -t are mutually exclusive and -t has priority.

@item -to @var{position} (@emph{output})
Stop writing the output at @var{position}.
@var{position} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.

-to and -t are mutually exclusive and -t has priority.

292
@item -fs @var{limit_size} (@emph{output})
293
Set the file size limit, expressed in bytes.
294

295 296
@item -ss @var{position} (@emph{input/output})
When used as an input option (before @code{-i}), seeks in this input file to
297
@var{position}. Note the in most formats it is not possible to seek exactly, so
298
@command{ffmpeg} will seek to the closest seek point before @var{position}.
299 300 301 302 303 304 305
When transcoding and @option{-accurate_seek} is enabled (the default), this
extra segment between the seek point and @var{position} will be decoded and
discarded. When doing stream copy or when @option{-noaccurate_seek} is used, it
will be preserved.

When used as an output option (before an output filename), decodes but discards
input until the timestamps reach @var{position}.
306

307 308 309
@var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form.

@item -itsoffset @var{offset} (@emph{input})
310
Set the input time offset.
311

312 313 314 315 316 317 318 319
@var{offset} must be a time duration specification,
see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.

The offset is added to the timestamps of the input files. Specifying
a positive offset means that the corresponding streams are delayed by
the time duration specified in @var{offset}.

@item -timestamp @var{date} (@emph{output})
320
Set the recording timestamp in the container.
321 322 323

@var{date} must be a time duration specification,
see @ref{date syntax,,the Date section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
324

325
@item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata})
Stefano Sabatini's avatar
Stefano Sabatini committed
326
Set a metadata key/value pair.
327

328 329 330 331 332 333 334
An optional @var{metadata_specifier} may be given to set metadata
on streams or chapters. See @code{-map_metadata} documentation for
details.

This option overrides metadata set with @code{-map_metadata}. It is
also possible to delete metadata by using an empty value.

335
For example, for setting the title in the output file:
336
@example
337
ffmpeg -i in.avi -metadata title="my title" out.flv
338
@end example
339

Michael Niedermayer's avatar
Michael Niedermayer committed
340
To set the language of the first audio stream:
341
@example
342
ffmpeg -i INPUT -metadata:s:a:0 language=eng OUTPUT
343 344 345
@end example

@item -target @var{type} (@emph{output})
346 347 348 349
Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv},
@code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or
@code{film-} to use the corresponding standard. All the format options
(bitrate, codecs, buffer sizes) are then set automatically. You can just type:
Fabrice Bellard's avatar
Fabrice Bellard committed
350 351 352 353 354

@example
ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
@end example

Diego Biurrun's avatar
Diego Biurrun committed
355 356
Nevertheless you can specify additional options as long as you know
they do not conflict with the standard, as in:
357 358 359 360 361

@example
ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
@end example

362
@item -dframes @var{number} (@emph{output})
363
Set the number of data frames to output. This is an alias for @code{-frames:d}.
364

365 366
@item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
Stop writing to the stream after @var{framecount} frames.
367

368 369
@item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
@itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
370
Use fixed quality scale (VBR). The meaning of @var{q}/@var{qscale} is
371
codec-dependent.
372 373 374 375 376
If @var{qscale} is used without a @var{stream_specifier} then it applies only
to the video stream, this is to maintain compatibility with previous behavior
and as specifying the same codec specific value to 2 different codecs that is
audio and video generally is not what is intended when no stream_specifier is
used.
377

378
@anchor{filter_option}
379 380
@item -filter[:@var{stream_specifier}] @var{filtergraph} (@emph{output,per-stream})
Create the filtergraph specified by @var{filtergraph} and use it to
381 382
filter the stream.

383
@var{filtergraph} is a description of the filtergraph to apply to
384
the stream, and must have a single input and a single output of the
385
same type of the stream. In the filtergraph, the input is associated
386 387 388 389 390
to the label @code{in}, and the output to the label @code{out}. See
the ffmpeg-filters manual for more information about the filtergraph
syntax.

See the @ref{filter_complex_option,,-filter_complex option} if you
391
want to create filtergraphs with multiple inputs and/or outputs.
392

393 394 395 396 397
@item -filter_script[:@var{stream_specifier}] @var{filename} (@emph{output,per-stream})
This option is similar to @option{-filter}, the only difference is that its
argument is the name of the file from which a filtergraph description is to be
read.

Michael Niedermayer's avatar
Michael Niedermayer committed
398 399 400 401
@item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
Specify the preset for matching stream(s).

@item -stats (@emph{global})
402 403
Print encoding progress/statistics. It is on by default, to explicitly
disable it you need to specify @code{-nostats}.
Michael Niedermayer's avatar
Michael Niedermayer committed
404

405 406 407 408 409 410 411 412
@item -progress @var{url} (@emph{global})
Send program-friendly progress information to @var{url}.

Progress information is written approximately every second and at the end of
the encoding process. It is made of "@var{key}=@var{value}" lines. @var{key}
consists of only alphanumeric characters. The last key of a sequence of
progress information is always "progress".

413 414
@item -stdin
Enable interaction on standard input. On by default unless standard input is
415 416
used as an input. To explicitly disable interaction you need to specify
@code{-nostdin}.
417

418 419 420 421
Disabling interaction on standard input is useful, for example, if
ffmpeg is in the background process group. Roughly the same result can
be achieved with @code{ffmpeg ... < /dev/null} but it requires a
shell.
422

423 424 425 426 427 428 429 430
@item -debug_ts (@emph{global})
Print timestamp information. It is off by default. This option is
mostly useful for testing and debugging purposes, and the output
format may change from one version to another, so it should not be
employed by portable scripts.

See also the option @code{-fdebug ts}.

Michael Niedermayer's avatar
Michael Niedermayer committed
431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452
@item -attach @var{filename} (@emph{output})
Add an attachment to the output file. This is supported by a few formats
like Matroska for e.g. fonts used in rendering subtitles. Attachments
are implemented as a specific type of stream, so this option will add
a new stream to the file. It is then possible to use per-stream options
on this stream in the usual way. Attachment streams created with this
option will be created after all the other streams (i.e. those created
with @code{-map} or automatic mappings).

Note that for Matroska you also have to set the mimetype metadata tag:
@example
ffmpeg -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
@end example
(assuming that the attachment stream will be third in the output file).

@item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream})
Extract the matching attachment stream into a file named @var{filename}. If
@var{filename} is empty, then the value of the @code{filename} metadata tag
will be used.

E.g. to extract the first attachment to a file named 'out.ttf':
@example
453
ffmpeg -dump_attachment:t:0 out.ttf -i INPUT
Michael Niedermayer's avatar
Michael Niedermayer committed
454 455 456
@end example
To extract all attachments to files determined by the @code{filename} tag:
@example
457
ffmpeg -dump_attachment:t "" -i INPUT
Michael Niedermayer's avatar
Michael Niedermayer committed
458 459 460 461 462
@end example

Technical note -- attachments are implemented as codec extradata, so this
option can actually be used to extract extradata from any stream, not just
attachments.
463

464 465 466 467
@end table

@section Video Options

468
@table @option
469
@item -vframes @var{number} (@emph{output})
470
Set the number of video frames to output. This is an alias for @code{-frames:v}.
471
@item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
472 473 474 475
Set frame rate (Hz value, fraction or abbreviation).

As an input option, ignore any timestamps stored in the file and instead
generate timestamps assuming constant frame rate @var{fps}.
476 477 478
This is not the same as the @option{-framerate} option used for some input formats
like image2 or v4l2 (it used to be the same in older versions of FFmpeg).
If in doubt use @option{-framerate} instead of the input option @option{-r}.
479 480

As an output option, duplicate or drop input frames to achieve constant output
481
frame rate @var{fps}.
482

483
@item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
484 485 486 487 488 489 490 491 492 493
Set frame size.

As an input option, this is a shortcut for the @option{video_size} private
option, recognized by some demuxers for which the frame size is either not
stored in the file or is configurable -- e.g. raw video or video grabbers.

As an output option, this inserts the @code{scale} video filter to the
@emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
directly to insert it at the beginning or some other place.

494
The format is @samp{wxh} (default - same as source).
Fabrice Bellard's avatar
Fabrice Bellard committed
495

496
@item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
497 498 499 500 501 502 503
Set the video display aspect ratio specified by @var{aspect}.

@var{aspect} can be a floating point number string, or a string of the
form @var{num}:@var{den}, where @var{num} and @var{den} are the
numerator and denominator of the aspect ratio. For example "4:3",
"16:9", "1.3333", and "1.7777" are valid argument values.

504 505 506 507
If used together with @option{-vcodec copy}, it will affect the aspect ratio
stored at container level, but not the aspect ratio stored in encoded
frames, if it exists.

508
@item -vn (@emph{output})
Diego Biurrun's avatar
Diego Biurrun committed
509
Disable video recording.
510

511 512 513
@item -vcodec @var{codec} (@emph{output})
Set the video codec. This is an alias for @code{-codec:v}.

514
@item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
515 516 517 518 519
Select the pass number (1 or 2). It is used to do two-pass
video encoding. The statistics of the video are recorded in the first
pass into a log file (see also the option -passlogfile),
and in the second pass that log file is used to generate the video
at the exact requested bitrate.
520 521 522
On pass 1, you may just deactivate audio and set output to null,
examples for Windows and Unix:
@example
523 524
ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
525
@end example
526

527
@item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
528 529 530
Set two-pass log file name prefix to @var{prefix}, the default file name
prefix is ``ffmpeg2pass''. The complete file name will be
@file{PREFIX-N.log}, where N is a number specific to the output
531
stream
532

533 534
@item -vf @var{filtergraph} (@emph{output})
Create the filtergraph specified by @var{filtergraph} and use it to
535
filter the stream.
536

537
This is an alias for @code{-filter:v}, see the @ref{filter_option,,-filter option}.
538 539
@end table

540
@section Advanced Video options
541

542
@table @option
543 544
@item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
Set pixel format. Use @code{-pix_fmts} to show all the supported
545
pixel formats.
546 547 548 549
If the selected pixel format can not be selected, ffmpeg will print a
warning and select the best pixel format supported by the encoder.
If @var{pix_fmt} is prefixed by a @code{+}, ffmpeg will exit with an error
if the requested pixel format can not be selected, and automatic conversions
550
inside filtergraphs are disabled.
551 552 553
If @var{pix_fmt} is a single @code{+}, ffmpeg selects the same pixel format
as the input (or graph output) and automatic conversions are disabled.

554
@item -sws_flags @var{flags} (@emph{input/output})
555
Set SwScaler flags.
556
@item -vdt @var{n}
557
Discard threshold.
Stefano Sabatini's avatar
Stefano Sabatini committed
558

559
@item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
560
Rate control override for specific intervals, formatted as "int,int,int"
561 562 563
list separated with slashes. Two first values are the beginning and
end frame numbers, last one is quantizer to use if positive, or quality
factor if negative.
Fabrice Bellard's avatar
Fabrice Bellard committed
564

565
@item -ilme
Diego Biurrun's avatar
Diego Biurrun committed
566 567 568 569 570
Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
Use this option if your input file is interlaced and you want
to keep the interlaced format for minimum losses.
The alternative is to deinterlace the input stream with
@option{-deinterlace}, but deinterlacing introduces losses.
Fabrice Bellard's avatar
Fabrice Bellard committed
571
@item -psnr
Diego Biurrun's avatar
Diego Biurrun committed
572
Calculate PSNR of compressed frames.
Fabrice Bellard's avatar
Fabrice Bellard committed
573
@item -vstats
Diego Biurrun's avatar
Diego Biurrun committed
574
Dump video coding statistics to @file{vstats_HHMMSS.log}.
575
@item -vstats_file @var{file}
576
Dump video coding statistics to @var{file}.
577
@item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
578
top=1/bottom=0/auto=-1 field first
579
@item -dc @var{precision}
580
Intra_dc_precision.
581 582 583 584
@item -vtag @var{fourcc/tag} (@emph{output})
Force video tag/fourcc. This is an alias for @code{-tag:v}.
@item -qphist (@emph{global})
Show QP histogram
585
@item -vbsf @var{bitstream_filter}
586
Deprecated see -bsf
587

588
@item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
589
@item -force_key_frames[:@var{stream_specifier}] expr:@var{expr} (@emph{output,per-stream})
590 591
Force key frames at the specified timestamps, more precisely at the first
frames after each specified time.
592 593 594 595 596

If the argument is prefixed with @code{expr:}, the string @var{expr}
is interpreted like an expression and is evaluated for each frame. A
key frame is forced in case the evaluation is non-zero.

597 598 599
If one of the times is "@code{chapters}[@var{delta}]", it is expanded into
the time of the beginning of all chapters in the file, shifted by
@var{delta}, expressed as a time in seconds.
600 601
This option can be useful to ensure that a seek point is present at a
chapter mark or any other designated place in the output file.
602 603 604 605 606 607

For example, to insert a key frame at 5 minutes, plus key frames 0.1 second
before the beginning of every chapter:
@example
-force_key_frames 0:05:00,chapters-0.1
@end example
Michael Niedermayer's avatar
Michael Niedermayer committed
608

609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639
The expression in @var{expr} can contain the following constants:
@table @option
@item n
the number of current processed frame, starting from 0
@item n_forced
the number of forced frames
@item prev_forced_n
the number of the previous forced frame, it is @code{NAN} when no
keyframe was forced yet
@item prev_forced_t
the time of the previous forced frame, it is @code{NAN} when no
keyframe was forced yet
@item t
the time of the current processed frame
@end table

For example to force a key frame every 5 seconds, you can specify:
@example
-force_key_frames expr:gte(t,n_forced*5)
@end example

To force a key frame 5 seconds after the time of the last forced one,
starting from second 13:
@example
-force_key_frames expr:if(isnan(prev_forced_t),gte(t,13),gte(t,prev_forced_t+5))
@end example

Note that forcing too many keyframes is very harmful for the lookahead
algorithms of certain encoders: using fixed-GOP options or similar
would be more efficient.

Michael Niedermayer's avatar
Michael Niedermayer committed
640 641 642
@item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
When doing stream copy, copy also non-key frames found at the
beginning.
643 644 645 646 647 648 649 650 651 652

@item -hwaccel[:@var{stream_specifier}] @var{hwaccel} (@emph{input,per-stream})
Use hardware acceleration to decode the matching stream(s). The allowed values
of @var{hwaccel} are:
@table @option
@item none
Do not use any hardware acceleration (the default).

@item auto
Automatically select the hardware acceleration method.
653

654 655 656
@item vda
Use Apple VDA hardware acceleration.

657 658
@item vdpau
Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.
659 660 661

@item dxva2
Use DXVA2 (DirectX Video Acceleration) hardware acceleration.
662 663 664 665 666 667
@end table

This option has no effect if the selected hwaccel is not available or not
supported by the chosen decoder.

Note that most acceleration methods are intended for playback and will not be
668
faster than software decoding on modern CPUs. Additionally, @command{ffmpeg}
669 670 671 672 673 674 675 676 677 678
will usually need to copy the decoded frames from the GPU memory into the system
memory, resulting in further performance loss. This option is thus mainly
useful for testing.

@item -hwaccel_device[:@var{stream_specifier}] @var{hwaccel_device} (@emph{input,per-stream})
Select a device to use for hardware acceleration.

This option only makes sense when the @option{-hwaccel} option is also
specified. Its exact meaning depends on the specific hardware acceleration
method chosen.
679 680 681 682 683

@table @option
@item vdpau
For VDPAU, this option specifies the X11 display/screen to use. If this option
is not specified, the value of the @var{DISPLAY} environment variable is used
684 685 686 687

@item dxva2
For DXVA2, this option should contain the number of the display adapter to use.
If this option is not specified, the default adapter is used.
688
@end table
Fabrice Bellard's avatar
Fabrice Bellard committed
689 690 691 692 693
@end table

@section Audio Options

@table @option
694
@item -aframes @var{number} (@emph{output})
695
Set the number of audio frames to output. This is an alias for @code{-frames:a}.
696
@item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
697 698 699 700
Set the audio sampling frequency. For output streams it is set by
default to the frequency of the corresponding input stream. For input
streams this option only makes sense for audio grabbing devices and raw
demuxers and is mapped to the corresponding demuxer options.
701 702 703
@item -aq @var{q} (@emph{output})
Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
@item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
704 705 706 707
Set the number of audio channels. For output streams it is set by
default to the number of input audio channels. For input streams
this option only makes sense for audio grabbing devices and raw demuxers
and is mapped to the corresponding demuxer options.
708
@item -an (@emph{output})
Diego Biurrun's avatar
Diego Biurrun committed
709
Disable audio recording.
710 711 712
@item -acodec @var{codec} (@emph{input/output})
Set the audio codec. This is an alias for @code{-codec:a}.
@item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
Michael Niedermayer's avatar
Michael Niedermayer committed
713
Set the audio sample format. Use @code{-sample_fmts} to get a list
714
of supported sample formats.
715

716 717
@item -af @var{filtergraph} (@emph{output})
Create the filtergraph specified by @var{filtergraph} and use it to
718 719 720
filter the stream.

This is an alias for @code{-filter:a}, see the @ref{filter_option,,-filter option}.
721 722
@end table

723
@section Advanced Audio options
724 725

@table @option
726 727
@item -atag @var{fourcc/tag} (@emph{output})
Force audio tag/fourcc. This is an alias for @code{-tag:a}.
728
@item -absf @var{bitstream_filter}
729
Deprecated, see -bsf
730 731 732 733 734 735
@item -guess_layout_max @var{channels} (@emph{input,per-stream})
If some input channel layout is not known, try to guess only if it
corresponds to at most the specified number of channels. For example, 2
tells to @command{ffmpeg} to recognize 1 channel as mono and 2 channels as
stereo but not 6 channels as 5.1. The default is to always try to guess. Use
0 to disable all guessing.
736 737
@end table

738
@section Subtitle options
739 740

@table @option
741 742 743
@item -scodec @var{codec} (@emph{input/output})
Set the subtitle codec. This is an alias for @code{-codec:s}.
@item -sn (@emph{output})
Diego Biurrun's avatar
Diego Biurrun committed
744
Disable subtitle recording.
745
@item -sbsf @var{bitstream_filter}
746
Deprecated, see -bsf
Fabrice Bellard's avatar
Fabrice Bellard committed
747 748
@end table

749
@section Advanced Subtitle options
750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765

@table @option

@item -fix_sub_duration
Fix subtitles durations. For each subtitle, wait for the next packet in the
same stream and adjust the duration of the first to avoid overlap. This is
necessary with some subtitles codecs, especially DVB subtitles, because the
duration in the original packet is only a rough estimate and the end is
actually marked by an empty subtitle frame. Failing to use this option when
necessary can result in exaggerated durations or muxing failures due to
non-monotonic timestamps.

Note that this option will delay the output of all data until the next
subtitle packet is decoded: it may increase memory consumption and latency a
lot.

766 767 768
@item -canvas_size @var{size}
Set the size of the canvas used to render subtitles.

769 770
@end table

Fabrice Bellard's avatar
Fabrice Bellard committed
771 772 773
@section Advanced options

@table @option
774
@item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
775

776
Designate one or more input streams as a source for the output file. Each input
777 778
stream is identified by the input file index @var{input_file_id} and
the input stream index @var{input_stream_id} within the input
779 780
file. Both indices start at 0. If specified,
@var{sync_file_id}:@var{stream_specifier} sets which input stream
781 782
is used as a presentation sync reference.

783
The first @code{-map} option on the command line specifies the
784 785 786
source for output stream 0, the second @code{-map} option specifies
the source for output stream 1, etc.

787 788 789
A @code{-} character before the stream identifier creates a "negative" mapping.
It disables matching streams from already created mappings.

790 791 792 793
An alternative @var{[linklabel]} form will map outputs from complex filter
graphs (see the @option{-filter_complex} option) to the output file.
@var{linklabel} must correspond to a defined output link label in the graph.

794 795 796 797 798
For example, to map ALL streams from the first input file to output
@example
ffmpeg -i INPUT -map 0 output
@end example

799
For example, if you have two audio streams in the first input file,
800 801
these streams are identified by "0:0" and "0:1". You can use
@code{-map} to select which streams to place in an output file. For
802 803
example:
@example
804
ffmpeg -i INPUT -map 0:1 out.wav
805
@end example
806
will map the input stream in @file{INPUT} identified by "0:1" to
807 808 809
the (single) output stream in @file{out.wav}.

For example, to select the stream with index 2 from input file
810 811
@file{a.mov} (specified by the identifier "0:2"), and stream with
index 6 from input @file{b.mov} (specified by the identifier "1:6"),
812 813
and copy them to the output file @file{out.mov}:
@example
814
ffmpeg -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
815 816
@end example

817 818 819 820
To select all video and the third audio stream from an input file:
@example
ffmpeg -i INPUT -map 0:v -map 0:a:2 OUTPUT
@end example
821

822 823 824 825
To map all the streams except the second audio, use negative mappings
@example
ffmpeg -i INPUT -map 0 -map -0:a:1 OUTPUT
@end example
826

827 828
To pick the English audio stream:
@example
Michael Niedermayer's avatar
Michael Niedermayer committed
829
ffmpeg -i INPUT -map 0:m:language:eng OUTPUT
830 831
@end example

832 833
Note that using this option disables the default mappings for this output file.

834 835
@item -map_channel [@var{input_file_id}.@var{stream_specifier}.@var{channel_id}|-1][:@var{output_file_id}.@var{stream_specifier}]
Map an audio channel from a given input to an output. If
836
@var{output_file_id}.@var{stream_specifier} is not set, the audio channel will
837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857
be mapped on all the audio streams.

Using "-1" instead of
@var{input_file_id}.@var{stream_specifier}.@var{channel_id} will map a muted
channel.

For example, assuming @var{INPUT} is a stereo audio file, you can switch the
two audio channels with the following command:
@example
ffmpeg -i INPUT -map_channel 0.0.1 -map_channel 0.0.0 OUTPUT
@end example

If you want to mute the first channel and keep the second:
@example
ffmpeg -i INPUT -map_channel -1 -map_channel 0.0.1 OUTPUT
@end example

The order of the "-map_channel" option specifies the order of the channels in
the output stream. The output channel layout is guessed from the number of
channels mapped (mono if one "-map_channel", stereo if two, etc.). Using "-ac"
in combination of "-map_channel" makes the channel gain levels to be updated if
858 859
input and output channel layouts don't match (for instance two "-map_channel"
options and "-ac 6").
860

861 862 863
You can also extract each channel of an input to specific outputs; the following
command extracts two channels of the @var{INPUT} audio stream (file 0, stream 0)
to the respective @var{OUTPUT_CH0} and @var{OUTPUT_CH1} outputs:
864 865 866 867
@example
ffmpeg -i INPUT -map_channel 0.0.0 OUTPUT_CH0 -map_channel 0.0.1 OUTPUT_CH1
@end example

868 869
The following example splits the channels of a stereo input into two separate
streams, which are put into the same output file:
870 871 872 873
@example
ffmpeg -i stereo.wav -map 0:0 -map 0:0 -map_channel 0.0.0:0.0 -map_channel 0.0.1:0.1 -y out.ogg
@end example

874 875 876 877 878
Note that currently each output stream can only contain channels from a single
input stream; you can't for example use "-map_channel" to pick multiple input
audio channels contained in different streams (from the same or different files)
and merge them into a single output stream. It is therefore not currently
possible, for example, to turn two separate mono streams into a single stereo
879
stream. However splitting a stereo stream into two single channel mono streams
880
is possible.
881

882 883 884
If you need this feature, a possible workaround is to use the @emph{amerge}
filter. For example, if you need to merge a media (here @file{input.mkv}) with 2
mono audio streams into one single stereo channel audio stream (and keep the
885
video stream), you can use the following command:
886
@example
887
ffmpeg -i input.mkv -filter_complex "[0:1] [0:2] amerge" -c:a pcm_s16le -c:v copy output.mkv
888 889
@end example

Michael Niedermayer's avatar
Michael Niedermayer committed
890
@item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
891 892
Set metadata information of the next output file from @var{infile}. Note that
those are file indices (zero-based), not filenames.
Michael Niedermayer's avatar
Michael Niedermayer committed
893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911
Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
A metadata specifier can have the following forms:
@table @option
@item @var{g}
global metadata, i.e. metadata that applies to the whole file

@item @var{s}[:@var{stream_spec}]
per-stream metadata. @var{stream_spec} is a stream specifier as described
in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
matching stream is copied from. In an output metadata specifier, all matching
streams are copied to.

@item @var{c}:@var{chapter_index}
per-chapter metadata. @var{chapter_index} is the zero-based chapter index.

@item @var{p}:@var{program_index}
per-program metadata. @var{program_index} is the zero-based program index.
@end table
If metadata specifier is omitted, it defaults to global.
912

913
By default, global metadata is copied from the first input file,
914 915 916 917
per-stream and per-chapter metadata is copied along with streams/chapters. These
default mappings are disabled by creating any mapping of the relevant type. A negative
file index can be used to create a dummy mapping that just disables automatic copying.

918 919 920
For example to copy metadata from the first stream of the input file to global metadata
of the output file:
@example
921
ffmpeg -i in.ogg -map_metadata 0:s:0 out.mp3
922
@end example
Michael Niedermayer's avatar
Michael Niedermayer committed
923 924 925 926 927 928 929 930

To do the reverse, i.e. copy global metadata to all audio streams:
@example
ffmpeg -i in.mkv -map_metadata:s:a 0:g out.mkv
@end example
Note that simple @code{0} would work as well in this example, since global
metadata is assumed by default.

931 932 933 934 935
@item -map_chapters @var{input_file_index} (@emph{output})
Copy chapters from input file with index @var{input_file_index} to the next
output file. If no chapter mapping is specified, then chapters are copied from
the first input file with at least one chapter. Use a negative file index to
disable any chapter copying.
936

937
@item -benchmark (@emph{global})
938 939 940 941
Show benchmarking information at the end of an encode.
Shows CPU time used and maximum memory consumption.
Maximum memory consumption is not supported on all systems,
it will usually display as 0 if not supported.
942 943 944
@item -benchmark_all (@emph{global})
Show benchmarking information during the encode.
Shows CPU time used in various steps (audio/video encode/decode).
945 946
@item -timelimit @var{duration} (@emph{global})
Exit after ffmpeg has been running for @var{duration} seconds.
947
@item -dump (@emph{global})
948
Dump each input packet to stderr.
949
@item -hex (@emph{global})
950
When dumping packets, also dump the payload.
951
@item -re (@emph{input})
Diego Biurrun's avatar
Diego Biurrun committed
952
Read input at native frame rate. Mainly used to simulate a grab device.
953 954 955
or live input stream (e.g. when reading from a file). Should not be used
with actual grab devices or live input streams (where it can cause packet
loss).
956 957
By default @command{ffmpeg} attempts to read the input(s) as fast as possible.
This option will slow down the reading of the input(s) to the native frame rate
958
of the input(s). It is useful for real-time output (e.g. live streaming).
959
@item -loop_input
Diego Biurrun's avatar
Diego Biurrun committed
960 961
Loop over the input stream. Currently it works only for image
streams. This option is used for automatic FFserver testing.
Carl Eugen Hoyos's avatar
Carl Eugen Hoyos committed
962
This option is deprecated, use -loop 1.
963
@item -loop_output @var{number_of_times}
Diego Biurrun's avatar
Diego Biurrun committed
964
Repeatedly loop output for formats that support looping such as animated GIF
Diego Biurrun's avatar
Diego Biurrun committed
965
(0 will loop the output infinitely).
966
This option is deprecated, use -loop.
967
@item -vsync @var{parameter}
968
Video sync method.
Reimar Döffinger's avatar
Reimar Döffinger committed
969 970
For compatibility reasons old values can be specified as numbers.
Newly added values will have to be specified as strings always.
971 972

@table @option
973
@item 0, passthrough
974
Each frame is passed with its timestamp from the demuxer to the muxer.
975
@item 1, cfr
976
Frames will be duplicated and dropped to achieve exactly the requested
977
constant frame rate.
978
@item 2, vfr
979 980
Frames are passed through with their timestamp or dropped so as to
prevent 2 frames from having the same timestamp.
Reimar Döffinger's avatar
Reimar Döffinger committed
981 982 983
@item drop
As passthrough but destroys all timestamps, making the muxer generate
fresh timestamps based on frame-rate.
984
@item -1, auto
985 986 987 988
Chooses between 1 and 2 depending on muxer capabilities. This is the
default method.
@end table

989 990 991 992
Note that the timestamps may be further modified by the muxer, after this.
For example, in the case that the format option @option{avoid_negative_ts}
is enabled.

993 994 995 996
With -map you can select from which stream the timestamps should be
taken. You can leave either video or audio unchanged and sync the
remaining stream(s) to the unchanged one.

997
@item -async @var{samples_per_second}
998
Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
999 1000 1001
the parameter is the maximum samples per second by which the audio is changed.
-async 1 is a special case where only the start of the audio stream is corrected
without any later correction.
1002 1003 1004 1005 1006

Note that the timestamps may be further modified by the muxer, after this.
For example, in the case that the format option @option{avoid_negative_ts}
is enabled.

1007
This option has been deprecated. Use the @code{aresample} audio filter instead.
1008

1009
@item -copyts
1010 1011 1012 1013 1014
Do not process input timestamps, but keep their values without trying
to sanitize them. In particular, do not remove the initial start time
offset value.

Note that, depending on the @option{vsync} option or on specific muxer
1015 1016
processing (e.g. in case the format option @option{avoid_negative_ts}
is enabled) the output timestamps may mismatch with the input
1017 1018
timestamps even when this option is selected.

1019 1020 1021 1022 1023 1024
@item -start_at_zero
When used with @option{copyts}, shift input timestamps so they start at zero.

This means that using e.g. @code{-ss 50} will make output timestamps start at
50 seconds, regardless of what timestamp the input file started at.

1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048
@item -copytb @var{mode}
Specify how to set the encoder timebase when stream copying.  @var{mode} is an
integer numeric value, and can assume one of the following values:

@table @option
@item 1
Use the demuxer timebase.

The time base is copied to the output encoder from the corresponding input
demuxer. This is sometimes required to avoid non monotonically increasing
timestamps when copying video streams with variable frame rate.

@item 0
Use the decoder timebase.

The time base is copied to the output encoder from the corresponding input
decoder.

@item -1
Try to make the choice automatically, in order to generate a sane output.
@end table

Default value is -1.

1049
@item -shortest (@emph{output})
1050 1051 1052
Finish encoding when the shortest input stream ends.
@item -dts_delta_threshold
Timestamp discontinuity delta threshold.
1053
@item -muxdelay @var{seconds} (@emph{input})
1054
Set the maximum demux-decode delay.
1055
@item -muxpreload @var{seconds} (@emph{input})
1056
Set the initial demux-decode delay.
1057
@item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
1058 1059 1060 1061
Assign a new stream-id value to an output stream. This option should be
specified prior to the output filename to which it applies.
For the situation where multiple output files exist, a streamid
may be reassigned to a different value.
1062 1063 1064 1065 1066 1067

For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
an output mpegts file:
@example
ffmpeg -i infile -streamid 0:33 -streamid 1:36 out.ts
@end example
1068 1069

@item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
1070
Set bitstream filters for matching streams. @var{bitstream_filters} is
1071 1072 1073
a comma-separated list of bitstream filters. Use the @code{-bsfs} option
to get the list of bitstream filters.
@example
1074
ffmpeg -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
1075 1076
@end example
@example
1077
ffmpeg -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
1078 1079
@end example

1080
@item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{input/output,per-stream})
1081
Force a tag/fourcc for matching streams.
1082 1083 1084 1085 1086 1087 1088

@item -timecode @var{hh}:@var{mm}:@var{ss}SEP@var{ff}
Specify Timecode for writing. @var{SEP} is ':' for non drop timecode and ';'
(or '.') for drop.
@example
ffmpeg -i input.mpg -timecode 01:02:03.04 -r 30000/1001 -s ntsc output.mpg
@end example
1089

1090
@anchor{filter_complex_option}
1091
@item -filter_complex @var{filtergraph} (@emph{global})
1092
Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or
1093 1094
outputs. For simple graphs -- those with one input and one output of the same
type -- see the @option{-filter} options. @var{filtergraph} is a description of
1095
the filtergraph, as described in the ``Filtergraph syntax'' section of the
1096
ffmpeg-filters manual.
1097 1098 1099 1100 1101 1102 1103 1104 1105 1106

Input link labels must refer to input streams using the
@code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
uses). If @var{stream_specifier} matches multiple streams, the first one will be
used. An unlabeled input will be connected to the first unused input stream of
the matching type.

Output link labels are referred to with @option{-map}. Unlabeled outputs are
added to the first output file.

1107 1108 1109
Note that with this option it is possible to use only lavfi sources without
normal input files.

1110 1111
For example, to overlay an image over video
@example
1112
ffmpeg -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
1113 1114 1115 1116 1117 1118 1119 1120 1121 1122
'[out]' out.mkv
@end example
Here @code{[0:v]} refers to the first video stream in the first input file,
which is linked to the first (main) input of the overlay filter. Similarly the
first video stream in the second input is linked to the second (overlay) input
of overlay.

Assuming there is only one video stream in each input file, we can omit input
labels, so the above is equivalent to
@example
1123
ffmpeg -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
1124 1125 1126 1127 1128 1129
'[out]' out.mkv
@end example

Furthermore we can omit the output label and the single output from the filter
graph will be added to the output file automatically, so we can simply write
@example
1130
ffmpeg -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
1131
@end example
1132 1133 1134

To generate 5 seconds of pure red video using lavfi @code{color} source:
@example
1135
ffmpeg -filter_complex 'color=c=red' -t 5 out.mkv
1136
@end example
1137 1138

@item -lavfi @var{filtergraph} (@emph{global})
1139
Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or
1140 1141
outputs. Equivalent to @option{-filter_complex}.

1142 1143 1144 1145 1146
@item -filter_complex_script @var{filename} (@emph{global})
This option is similar to @option{-filter_complex}, the only difference is that
its argument is the name of the file from which a complex filtergraph
description is to be read.

1147 1148 1149 1150 1151 1152
@item -accurate_seek (@emph{input})
This option enables or disables accurate seeking in input files with the
@option{-ss} option. It is enabled by default, so seeking is accurate when
transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful
e.g. when copying some streams and transcoding the others.

1153
@item -override_ffserver (@emph{global})
1154 1155 1156 1157 1158 1159
Overrides the input specifications from @command{ffserver}. Using this
option you can map any input stream to @command{ffserver} and control
many aspects of the encoding from @command{ffmpeg}. Without this
option @command{ffmpeg} will transmit to @command{ffserver} what is
requested by @command{ffserver}.

1160
The option is intended for cases where features are needed that cannot be
1161
specified to @command{ffserver} but can be to @command{ffmpeg}.
1162

1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186
@item -discard (@emph{input})
Allows discarding specific streams or frames of streams at the demuxer.
Not all demuxers support this.

@table @option
@item none
Discard no frame.

@item default
Default, which discards no frames.

@item noref
Discard all non-reference frames.

@item bidir
Discard all bidirectional frames.

@item nokey
Discard all frames excepts keyframes.

@item all
Discard all frames.
@end table

1187
@end table
Fabrice Bellard's avatar
Fabrice Bellard committed
1188

1189 1190
As a special exception, you can use a bitmap subtitle stream as input: it
will be converted into a video with the same size as the largest video in
1191
the file, or 720x576 if no video is present. Note that this is an
1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204
experimental and temporary solution. It will be removed once libavfilter has
proper support for subtitles.

For example, to hardcode subtitles on top of a DVB-T recording stored in
MPEG-TS format, delaying the subtitles by 1 second:
@example
ffmpeg -i input.ts -filter_complex \
  '[#0x2ef] setpts=PTS+1/TB [sub] ; [#0x2d0] [sub] overlay' \
  -sn -map '#0x2dc' output.mkv
@end example
(0x2d0, 0x2dc and 0x2ef are the MPEG-TS PIDs of respectively the video,
audio and subtitles streams; 0:0, 0:3 and 0:7 would have worked too)

1205 1206 1207 1208 1209
@section Preset files
A preset file contains a sequence of @var{option}=@var{value} pairs,
one for each line, specifying a sequence of options which would be
awkward to specify on the command line. Lines starting with the hash
('#') character are ignored and are used to provide comments. Check
1210
the @file{presets} directory in the FFmpeg source tree for examples.
1211

1212 1213 1214 1215 1216
Preset files are specified with the @code{vpre}, @code{apre},
@code{spre}, and @code{fpre} options. The @code{fpre} option takes the
filename of the preset instead of a preset name as input and can be
used for any kind of codec. For the @code{vpre}, @code{apre}, and
@code{spre} options, the options specified in a preset file are
1217 1218
applied to the currently selected codec of the same type as the preset
option.
1219

1220 1221 1222
The argument passed to the @code{vpre}, @code{apre}, and @code{spre}
preset options identifies the preset file to use according to the
following rules:
1223 1224

First ffmpeg searches for a file named @var{arg}.ffpreset in the
1225 1226
directories @file{$FFMPEG_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in
the datadir defined at configuration time (usually @file{PREFIX/share/ffmpeg})
Gianluigi Tiesi's avatar
Gianluigi Tiesi committed
1227
or in a @file{ffpresets} folder along the executable on win32,
1228 1229
in that order. For example, if the argument is @code{libvpx-1080p}, it will
search for the file @file{libvpx-1080p.ffpreset}.
1230 1231 1232 1233 1234

If no such file is found, then ffmpeg will search for a file named
@var{codec_name}-@var{arg}.ffpreset in the above-mentioned
directories, where @var{codec_name} is the name of the codec to which
the preset file options will be applied. For example, if you select
1235 1236
the video codec with @code{-vcodec libvpx} and use @code{-vpre 1080p},
then it will search for the file @file{libvpx-1080p.ffpreset}.
1237
@c man end OPTIONS
1238

1239
@chapter Tips
1240
@c man begin TIPS
1241 1242

@itemize
1243
@item
1244
For streaming at very low bitrates, use a low frame rate
Diego Biurrun's avatar
Diego Biurrun committed
1245
and a small GOP size. This is especially true for RealVideo where
1246 1247
the Linux player does not seem to be very fast, so it can miss
frames. An example is:
1248 1249

@example
1250
ffmpeg -g 3 -r 3 -t 10 -b:v 50k -s qcif -f rv10 /tmp/b.rm
1251 1252
@end example

1253 1254
@item
The parameter 'q' which is displayed while encoding is the current
Diego Biurrun's avatar
Diego Biurrun committed
1255 1256
quantizer. The value 1 indicates that a very good quality could
be achieved. The value 31 indicates the worst quality. If q=31 appears
1257
too often, it means that the encoder cannot compress enough to meet
Diego Biurrun's avatar
Diego Biurrun committed
1258
your bitrate. You must either increase the bitrate, decrease the
1259
frame rate or decrease the frame size.
1260

1261 1262
@item
If your computer is not fast enough, you can speed up the
1263
compression at the expense of the compression ratio. You can use
1264
'-me zero' to speed up motion estimation, and '-g 0' to disable
Diego Biurrun's avatar
Diego Biurrun committed
1265
motion estimation completely (you have only I-frames, which means it
1266
is about as good as JPEG compression).
1267

1268 1269
@item
To have very low audio bitrates, reduce the sampling frequency
1270
(down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
1271

1272 1273
@item
To have a constant quality (but a variable bitrate), use the option
1274 1275
'-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
quality).
1276 1277

@end itemize
1278
@c man end TIPS
1279

1280 1281 1282
@chapter Examples
@c man begin EXAMPLES

Michael Niedermayer's avatar
Michael Niedermayer committed
1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297
@section Preset files

A preset file contains a sequence of @var{option=value} pairs, one for
each line, specifying a sequence of options which can be specified also on
the command line. Lines starting with the hash ('#') character are ignored and
are used to provide comments. Empty lines are also ignored. Check the
@file{presets} directory in the FFmpeg source tree for examples.

Preset files are specified with the @code{pre} option, this option takes a
preset name as input.  FFmpeg searches for a file named @var{preset_name}.avpreset in
the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in
the data directory defined at configuration time (usually @file{$PREFIX/share/ffmpeg})
in that order.  For example, if the argument is @code{libx264-max}, it will
search for the file @file{libx264-max.avpreset}.

1298 1299
@section Video and Audio grabbing

1300 1301
If you specify the input format and device then ffmpeg can grab video
and audio directly.
1302 1303 1304

@example
ffmpeg -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
1305 1306 1307 1308 1309
@end example

Or with an ALSA audio source (mono input, card id 1) instead of OSS:
@example
ffmpeg -f alsa -ac 1 -i hw:1 -f video4linux2 -i /dev/video0 /tmp/out.mpg
1310 1311 1312
@end example

Note that you must activate the right video source and channel before
1313 1314
launching ffmpeg with any TV viewer such as
@uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
1315 1316 1317 1318 1319
have to set the audio recording levels correctly with a
standard mixer.

@section X11 grabbing

1320
Grab the X11 display with ffmpeg via
1321 1322

@example
1323
ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0 /tmp/out.mpg
1324 1325 1326 1327 1328 1329
@end example

0.0 is display.screen number of your X11 server, same as
the DISPLAY environment variable.

@example
1330
ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0+10,20 /tmp/out.mpg
1331 1332
@end example

1333 1334
0.0 is display.screen number of your X11 server, same as the DISPLAY environment
variable. 10 is the x-offset and 20 the y-offset for the grabbing.
1335 1336 1337

@section Video and Audio file format conversion

1338
Any supported file format and protocol can serve as input to ffmpeg:
1339 1340

Examples:
1341 1342 1343
@itemize
@item
You can use YUV files as input:
1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357

@example
ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
@end example

It will use the files:
@example
/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
/tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
@end example

The Y files use twice the resolution of the U and V files. They are
raw files, without header. They can be generated by all decent video
decoders. You must specify the size of the image with the @option{-s} option
1358
if ffmpeg cannot guess it.
1359

1360 1361
@item
You can input from a raw YUV420P file:
1362 1363 1364 1365 1366 1367 1368 1369 1370

@example
ffmpeg -i /tmp/test.yuv /tmp/out.avi
@end example

test.yuv is a file containing raw YUV planar data. Each frame is composed
of the Y plane followed by the U and V planes at half vertical and
horizontal resolution.

1371 1372
@item
You can output to a raw YUV420P file:
1373 1374 1375 1376 1377

@example
ffmpeg -i mydivx.avi hugefile.yuv
@end example

1378 1379
@item
You can set several input files and output files:
1380 1381 1382 1383 1384 1385 1386 1387

@example
ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
@end example

Converts the audio file a.wav and the raw YUV video file a.yuv
to MPEG file a.mpg.

1388 1389
@item
You can also do audio and video conversions at the same time:
1390 1391 1392 1393 1394 1395 1396

@example
ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
@end example

Converts a.wav to MPEG audio at 22050 Hz sample rate.

1397 1398
@item
You can encode to several formats at the same time and define a
1399 1400 1401
mapping from input stream to output streams:

@example
1402
ffmpeg -i /tmp/a.wav -map 0:a -b:a 64k /tmp/a.mp2 -map 0:a -b:a 128k /tmp/b.mp2
1403 1404 1405 1406 1407 1408
@end example

Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
file:index' specifies which input stream is used for each output
stream, in the order of the definition of output streams.

1409 1410
@item
You can transcode decrypted VOBs:
1411 1412

@example
1413
ffmpeg -i snatch_1.vob -f avi -c:v mpeg4 -b:v 800k -g 300 -bf 2 -c:a libmp3lame -b:a 128k snatch.avi
1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426
@end example

This is a typical DVD ripping example; the input is a VOB file, the
output an AVI file with MPEG-4 video and MP3 audio. Note that in this
command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
input video. Furthermore, the audio stream is MP3-encoded so you need
to enable LAME support by passing @code{--enable-libmp3lame} to configure.
The mapping is particularly useful for DVD transcoding
to get the desired audio language.

NOTE: To see the supported input formats, use @code{ffmpeg -formats}.

1427 1428
@item
You can extract images from a video, or create a video from many images:
1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450

For extracting images from a video:
@example
ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
@end example

This will extract one video frame per second from the video and will
output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
etc. Images will be rescaled to fit the new WxH values.

If you want to extract just a limited number of frames, you can use the
above command in combination with the -vframes or -t option, or in
combination with -ss to start extracting from a certain point in time.

For creating a video from many images:
@example
ffmpeg -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
@end example

The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
composed of three digits padded with zeroes to express the sequence
number. It is the same syntax supported by the C printf function, but
1451 1452
only formats accepting a normal integer are suitable.

1453 1454 1455 1456 1457 1458 1459 1460 1461
When importing an image sequence, -i also supports expanding
shell-like wildcard patterns (globbing) internally, by selecting the
image2-specific @code{-pattern_type glob} option.

For example, for creating a video from filenames matching the glob pattern
@code{foo-*.jpeg}:
@example
ffmpeg -f image2 -pattern_type glob -i 'foo-*.jpeg' -r 12 -s WxH foo.avi
@end example
1462

1463 1464
@item
You can put many streams of the same type in the output:
1465 1466

@example
1467
ffmpeg -i test1.avi -i test2.avi -map 1:1 -map 1:0 -map 0:1 -map 0:0 -c copy -y test12.nut
1468 1469
@end example

1470 1471
The resulting output file @file{test12.nut} will contain the first four streams
from the input files in reverse order.
1472

1473 1474 1475
@item
To force CBR video output:
@example
1476
ffmpeg -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
1477 1478 1479 1480 1481 1482
@end example

@item
The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
but you may use the QP2LAMBDA constant to easily convert from 'q' units:
@example
1483
ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
1484 1485
@end example

1486
@end itemize
1487 1488
@c man end EXAMPLES

1489
@include config.texi
1490
@ifset config-all
1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513
@ifset config-avutil
@include utils.texi
@end ifset
@ifset config-avcodec
@include codecs.texi
@include bitstream_filters.texi
@end ifset
@ifset config-avformat
@include formats.texi
@include protocols.texi
@end ifset
@ifset config-avdevice
@include devices.texi
@end ifset
@ifset config-swresample
@include resampler.texi
@end ifset
@ifset config-swscale
@include scaler.texi
@end ifset
@ifset config-avfilter
@include filters.texi
@end ifset
1514 1515
@end ifset

1516 1517 1518
@chapter See Also

@ifhtml
1519 1520 1521 1522 1523 1524
@ifset config-all
@url{ffmpeg.html,ffmpeg}
@end ifset
@ifset config-not-all
@url{ffmpeg-all.html,ffmpeg-all},
@end ifset
1525 1526 1527 1528 1529
@url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
@url{ffmpeg-utils.html,ffmpeg-utils},
@url{ffmpeg-scaler.html,ffmpeg-scaler},
@url{ffmpeg-resampler.html,ffmpeg-resampler},
@url{ffmpeg-codecs.html,ffmpeg-codecs},
1530
@url{ffmpeg-bitstream-filters.html,ffmpeg-bitstream-filters},
1531 1532 1533 1534 1535 1536 1537
@url{ffmpeg-formats.html,ffmpeg-formats},
@url{ffmpeg-devices.html,ffmpeg-devices},
@url{ffmpeg-protocols.html,ffmpeg-protocols},
@url{ffmpeg-filters.html,ffmpeg-filters}
@end ifhtml

@ifnothtml
1538 1539 1540 1541 1542 1543
@ifset config-all
ffmpeg(1),
@end ifset
@ifset config-not-all
ffmpeg-all(1),
@end ifset
1544 1545 1546 1547 1548 1549
ffplay(1), ffprobe(1), ffserver(1),
ffmpeg-utils(1), ffmpeg-scaler(1), ffmpeg-resampler(1),
ffmpeg-codecs(1), ffmpeg-bitstream-filters(1), ffmpeg-formats(1),
ffmpeg-devices(1), ffmpeg-protocols(1), ffmpeg-filters(1)
@end ifnothtml

1550 1551
@include authors.texi

1552 1553 1554
@ignore

@setfilename ffmpeg
1555
@settitle ffmpeg video converter
1556 1557 1558

@end ignore

1559
@bye