mp3enc: allow omitting the id3v2 header with -id3v2_version 0
[libav.git] / doc / muxers.texi
1 @chapter Muxers
2 @c man begin MUXERS
4 Muxers are configured elements in Libav which allow writing
5 multimedia streams to a particular type of file.
7 When you configure your Libav build, all the supported muxers
8 are enabled by default. You can list all available muxers using the
9 configure option @code{--list-muxers}.
11 You can disable all the muxers with the configure option
12 @code{--disable-muxers} and selectively enable / disable single muxers
13 with the options @code{--enable-muxer=@var{MUXER}} /
14 @code{--disable-muxer=@var{MUXER}}.
16 The option @code{-formats} of the av* tools will display the list of
17 enabled muxers.
19 A description of some of the currently available muxers follows.
21 @anchor{crc}
22 @section crc
24 CRC (Cyclic Redundancy Check) testing format.
26 This muxer computes and prints the Adler-32 CRC of all the input audio
27 and video frames. By default audio frames are converted to signed
28 16-bit raw audio and video frames to raw video before computing the
29 CRC.
31 The output of the muxer consists of a single line of the form:
32 CRC=0x@var{CRC}, where @var{CRC} is a hexadecimal number 0-padded to
33 8 digits containing the CRC for all the decoded input frames.
35 For example to compute the CRC of the input, and store it in the file
36 @file{out.crc}:
37 @example
38 avconv -i INPUT -f crc out.crc
39 @end example
41 You can print the CRC to stdout with the command:
42 @example
43 avconv -i INPUT -f crc -
44 @end example
46 You can select the output format of each frame with @command{avconv} by
47 specifying the audio and video codec and format. For example to
48 compute the CRC of the input audio converted to PCM unsigned 8-bit
49 and the input video converted to MPEG-2 video, use the command:
50 @example
51 avconv -i INPUT -c:a pcm_u8 -c:v mpeg2video -f crc -
52 @end example
54 See also the @ref{framecrc} muxer.
56 @anchor{framecrc}
57 @section framecrc
59 Per-frame CRC (Cyclic Redundancy Check) testing format.
61 This muxer computes and prints the Adler-32 CRC for each decoded audio
62 and video frame. By default audio frames are converted to signed
63 16-bit raw audio and video frames to raw video before computing the
64 CRC.
66 The output of the muxer consists of a line for each audio and video
67 frame of the form: @var{stream_index}, @var{frame_dts},
68 @var{frame_size}, 0x@var{CRC}, where @var{CRC} is a hexadecimal
69 number 0-padded to 8 digits containing the CRC of the decoded frame.
71 For example to compute the CRC of each decoded frame in the input, and
72 store it in the file @file{out.crc}:
73 @example
74 avconv -i INPUT -f framecrc out.crc
75 @end example
77 You can print the CRC of each decoded frame to stdout with the command:
78 @example
79 avconv -i INPUT -f framecrc -
80 @end example
82 You can select the output format of each frame with @command{avconv} by
83 specifying the audio and video codec and format. For example, to
84 compute the CRC of each decoded input audio frame converted to PCM
85 unsigned 8-bit and of each decoded input video frame converted to
86 MPEG-2 video, use the command:
87 @example
88 avconv -i INPUT -c:a pcm_u8 -c:v mpeg2video -f framecrc -
89 @end example
91 See also the @ref{crc} muxer.
93 @anchor{hls}
94 @section hls
96 Apple HTTP Live Streaming muxer that segments MPEG-TS according to
97 the HTTP Live Streaming specification.
99 It creates a playlist file and numbered segment files. The output
100 filename specifies the playlist filename; the segment filenames
101 receive the same basename as the playlist, a sequential number and
102 a .ts extension.
104 @example
105 avconv -i in.nut out.m3u8
106 @end example
108 @table @option
109 @item -hls_time @var{seconds}
110 Set the segment length in seconds.
111 @item -hls_list_size @var{size}
112 Set the maximum number of playlist entries.
113 @item -hls_wrap @var{wrap}
114 Set the number after which index wraps.
115 @item -start_number @var{number}
116 Start the sequence from @var{number}.
117 @end table
119 @anchor{image2}
120 @section image2
122 Image file muxer.
124 The image file muxer writes video frames to image files.
126 The output filenames are specified by a pattern, which can be used to
127 produce sequentially numbered series of files.
128 The pattern may contain the string "%d" or "%0@var{N}d", this string
129 specifies the position of the characters representing a numbering in
130 the filenames. If the form "%0@var{N}d" is used, the string
131 representing the number in each filename is 0-padded to @var{N}
132 digits. The literal character '%' can be specified in the pattern with
133 the string "%%".
135 If the pattern contains "%d" or "%0@var{N}d", the first filename of
136 the file list specified will contain the number 1, all the following
137 numbers will be sequential.
139 The pattern may contain a suffix which is used to automatically
140 determine the format of the image files to write.
142 For example the pattern "img-%03d.bmp" will specify a sequence of
143 filenames of the form @file{img-001.bmp}, @file{img-002.bmp}, ...,
144 @file{img-010.bmp}, etc.
145 The pattern "img%%-%d.jpg" will specify a sequence of filenames of the
146 form @file{img%-1.jpg}, @file{img%-2.jpg}, ..., @file{img%-10.jpg},
147 etc.
149 The following example shows how to use @command{avconv} for creating a
150 sequence of files @file{img-001.jpeg}, @file{img-002.jpeg}, ...,
151 taking one image every second from the input video:
152 @example
153 avconv -i in.avi -vsync 1 -r 1 -f image2 'img-%03d.jpeg'
154 @end example
156 Note that with @command{avconv}, if the format is not specified with the
157 @code{-f} option and the output filename specifies an image file
158 format, the image2 muxer is automatically selected, so the previous
159 command can be written as:
160 @example
161 avconv -i in.avi -vsync 1 -r 1 'img-%03d.jpeg'
162 @end example
164 Note also that the pattern must not necessarily contain "%d" or
165 "%0@var{N}d", for example to create a single image file
166 @file{img.jpeg} from the input video you can employ the command:
167 @example
168 avconv -i in.avi -f image2 -frames:v 1 img.jpeg
169 @end example
171 @table @option
172 @item -start_number @var{number}
173 Start the sequence from @var{number}.
175 @item -update @var{number}
176 If @var{number} is nonzero, the filename will always be interpreted as just a
177 filename, not a pattern, and this file will be continuously overwritten with new
178 images.
180 @end table
182 @section MOV/MP4/ISMV
184 The mov/mp4/ismv muxer supports fragmentation. Normally, a MOV/MP4
185 file has all the metadata about all packets stored in one location
186 (written at the end of the file, it can be moved to the start for
187 better playback using the @command{qt-faststart} tool). A fragmented
188 file consists of a number of fragments, where packets and metadata
189 about these packets are stored together. Writing a fragmented
190 file has the advantage that the file is decodable even if the
191 writing is interrupted (while a normal MOV/MP4 is undecodable if
192 it is not properly finished), and it requires less memory when writing
193 very long files (since writing normal MOV/MP4 files stores info about
194 every single packet in memory until the file is closed). The downside
195 is that it is less compatible with other applications.
197 Fragmentation is enabled by setting one of the AVOptions that define
198 how to cut the file into fragments:
200 @table @option
201 @item -movflags frag_keyframe
202 Start a new fragment at each video keyframe.
203 @item -frag_duration @var{duration}
204 Create fragments that are @var{duration} microseconds long.
205 @item -frag_size @var{size}
206 Create fragments that contain up to @var{size} bytes of payload data.
207 @item -movflags frag_custom
208 Allow the caller to manually choose when to cut fragments, by
209 calling @code{av_write_frame(ctx, NULL)} to write a fragment with
210 the packets written so far. (This is only useful with other
211 applications integrating libavformat, not from @command{avconv}.)
212 @item -min_frag_duration @var{duration}
213 Don't create fragments that are shorter than @var{duration} microseconds long.
214 @end table
216 If more than one condition is specified, fragments are cut when
217 one of the specified conditions is fulfilled. The exception to this is
218 @code{-min_frag_duration}, which has to be fulfilled for any of the other
219 conditions to apply.
221 Additionally, the way the output file is written can be adjusted
222 through a few other options:
224 @table @option
225 @item -movflags empty_moov
226 Write an initial moov atom directly at the start of the file, without
227 describing any samples in it. Generally, an mdat/moov pair is written
228 at the start of the file, as a normal MOV/MP4 file, containing only
229 a short portion of the file. With this option set, there is no initial
230 mdat atom, and the moov atom only describes the tracks but has
231 a zero duration.
233 Files written with this option set do not work in QuickTime.
234 This option is implicitly set when writing ismv (Smooth Streaming) files.
235 @item -movflags separate_moof
236 Write a separate moof (movie fragment) atom for each track. Normally,
237 packets for all tracks are written in a moof atom (which is slightly
238 more efficient), but with this option set, the muxer writes one moof/mdat
239 pair for each track, making it easier to separate tracks.
241 This option is implicitly set when writing ismv (Smooth Streaming) files.
242 @item -movflags faststart
243 Run a second pass moving the index (moov atom) to the beginning of the file.
244 This operation can take a while, and will not work in various situations such
245 as fragmented output, thus it is not enabled by default.
246 @end table
248 Smooth Streaming content can be pushed in real time to a publishing
249 point on IIS with this muxer. Example:
250 @example
251 avconv -re @var{<normal input/transcoding options>} -movflags isml+frag_keyframe -f ismv http://server/publishingpoint.isml/Streams(Encoder1)
252 @end example
254 @section mpegts
256 MPEG transport stream muxer.
258 This muxer implements ISO 13818-1 and part of ETSI EN 300 468.
260 The muxer options are:
262 @table @option
263 @item -mpegts_original_network_id @var{number}
264 Set the original_network_id (default 0x0001). This is unique identifier
265 of a network in DVB. Its main use is in the unique identification of a
266 service through the path Original_Network_ID, Transport_Stream_ID.
267 @item -mpegts_transport_stream_id @var{number}
268 Set the transport_stream_id (default 0x0001). This identifies a
269 transponder in DVB.
270 @item -mpegts_service_id @var{number}
271 Set the service_id (default 0x0001) also known as program in DVB.
272 @item -mpegts_pmt_start_pid @var{number}
273 Set the first PID for PMT (default 0x1000, max 0x1f00).
274 @item -mpegts_start_pid @var{number}
275 Set the first PID for data packets (default 0x0100, max 0x0f00).
276 @end table
278 The recognized metadata settings in mpegts muxer are @code{service_provider}
279 and @code{service_name}. If they are not set the default for
280 @code{service_provider} is "Libav" and the default for
281 @code{service_name} is "Service01".
283 @example
284 avconv -i file.mpg -c copy \
285 -mpegts_original_network_id 0x1122 \
286 -mpegts_transport_stream_id 0x3344 \
287 -mpegts_service_id 0x5566 \
288 -mpegts_pmt_start_pid 0x1500 \
289 -mpegts_start_pid 0x150 \
290 -metadata service_provider="Some provider" \
291 -metadata service_name="Some Channel" \
292 -y out.ts
293 @end example
295 @section null
297 Null muxer.
299 This muxer does not generate any output file, it is mainly useful for
300 testing or benchmarking purposes.
302 For example to benchmark decoding with @command{avconv} you can use the
303 command:
304 @example
305 avconv -benchmark -i INPUT -f null out.null
306 @end example
308 Note that the above command does not read or write the @file{out.null}
309 file, but specifying the output file is required by the @command{avconv}
310 syntax.
312 Alternatively you can write the command as:
313 @example
314 avconv -benchmark -i INPUT -f null -
315 @end example
317 @section matroska
319 Matroska container muxer.
321 This muxer implements the matroska and webm container specs.
323 The recognized metadata settings in this muxer are:
325 @table @option
327 @item title=@var{title name}
328 Name provided to a single track
329 @end table
331 @table @option
333 @item language=@var{language name}
334 Specifies the language of the track in the Matroska languages form
335 @end table
337 @table @option
339 @item STEREO_MODE=@var{mode}
340 Stereo 3D video layout of two views in a single video track
341 @table @option
342 @item mono
343 video is not stereo
344 @item left_right
345 Both views are arranged side by side, Left-eye view is on the left
346 @item bottom_top
347 Both views are arranged in top-bottom orientation, Left-eye view is at bottom
348 @item top_bottom
349 Both views are arranged in top-bottom orientation, Left-eye view is on top
350 @item checkerboard_rl
351 Each view is arranged in a checkerboard interleaved pattern, Left-eye view being first
352 @item checkerboard_lr
353 Each view is arranged in a checkerboard interleaved pattern, Right-eye view being first
354 @item row_interleaved_rl
355 Each view is constituted by a row based interleaving, Right-eye view is first row
356 @item row_interleaved_lr
357 Each view is constituted by a row based interleaving, Left-eye view is first row
358 @item col_interleaved_rl
359 Both views are arranged in a column based interleaving manner, Right-eye view is first column
360 @item col_interleaved_lr
361 Both views are arranged in a column based interleaving manner, Left-eye view is first column
362 @item anaglyph_cyan_red
363 All frames are in anaglyph format viewable through red-cyan filters
364 @item right_left
365 Both views are arranged side by side, Right-eye view is on the left
366 @item anaglyph_green_magenta
367 All frames are in anaglyph format viewable through green-magenta filters
368 @item block_lr
369 Both eyes laced in one Block, Left-eye view is first
370 @item block_rl
371 Both eyes laced in one Block, Right-eye view is first
372 @end table
373 @end table
375 For example a 3D WebM clip can be created using the following command line:
376 @example
377 avconv -i sample_left_right_clip.mpg -an -c:v libvpx -metadata STEREO_MODE=left_right -y stereo_clip.webm
378 @end example
380 This muxer supports the following options:
382 @table @option
384 @item reserve_index_space
385 By default, this muxer writes the index for seeking (called cues in Matroska
386 terms) at the end of the file, because it cannot know in advance how much space
387 to leave for the index at the beginning of the file. However for some use cases
388 -- e.g. streaming where seeking is possible but slow -- it is useful to put the
389 index at the beginning of the file.
391 If this option is set to a non-zero value, the muxer will reserve a given amount
392 of space in the file header and then try to write the cues there when the muxing
393 finishes. If the available space does not suffice, muxing will fail. A safe size
394 for most use cases should be about 50kB per hour of video.
396 Note that cues are only written if the output is seekable and this option will
397 have no effect if it is not.
399 @end table
401 @section segment
403 Basic stream segmenter.
405 The segmenter muxer outputs streams to a number of separate files of nearly
406 fixed duration. Output filename pattern can be set in a fashion similar to
407 @ref{image2}.
409 Every segment starts with a video keyframe, if a video stream is present.
410 The segment muxer works best with a single constant frame rate video.
412 Optionally it can generate a flat list of the created segments, one segment
413 per line.
415 @table @option
416 @item segment_format @var{format}
417 Override the inner container format, by default it is guessed by the filename
418 extension.
419 @item segment_time @var{t}
420 Set segment duration to @var{t} seconds.
421 @item segment_list @var{name}
422 Generate also a listfile named @var{name}.
423 @item segment_list_size @var{size}
424 Overwrite the listfile once it reaches @var{size} entries.
425 @item segment_wrap @var{limit}
426 Wrap around segment index once it reaches @var{limit}.
427 @end table
429 @example
430 avconv -i in.mkv -c copy -map 0 -f segment -list out.list out%03d.nut
431 @end example
433 @section mp3
435 The MP3 muxer writes a raw MP3 stream with an ID3v2 header at the beginning and
436 optionally an ID3v1 tag at the end. ID3v2.3 and ID3v2.4 are supported, the
437 @code{id3v2_version} option controls which one is used. Setting
438 @code{id3v2_version} to 0 will disable the ID3v2 header completely. The legacy
439 ID3v1 tag is not written by default, but may be enabled with the
440 @code{write_id3v1} option.
442 The muxer may also write a Xing frame at the beginning, which contains the
443 number of frames in the file. It is useful for computing duration of VBR files.
444 The Xing frame is written if the output stream is seekable and if the
445 @code{write_xing} option is set to 1 (the default).
447 The muxer supports writing ID3v2 attached pictures (APIC frames). The pictures
448 are supplied to the muxer in form of a video stream with a single packet. There
449 can be any number of those streams, each will correspond to a single APIC frame.
450 The stream metadata tags @var{title} and @var{comment} map to APIC
451 @var{description} and @var{picture type} respectively. See
452 @url{} for allowed picture types.
454 Note that the APIC frames must be written at the beginning, so the muxer will
455 buffer the audio frames until it gets all the pictures. It is therefore advised
456 to provide the pictures as soon as possible to avoid excessive buffering.
458 Examples:
460 Write an mp3 with an ID3v2.3 header and an ID3v1 footer:
461 @example
462 avconv -i INPUT -id3v2_version 3 -write_id3v1 1 out.mp3
463 @end example
465 Attach a picture to an mp3:
466 @example
467 avconv -i input.mp3 -i cover.png -c copy -metadata:s:v title="Album cover"
468 -metadata:s:v comment="Cover (Front)" out.mp3
469 @end example
471 Write a "clean" MP3 without any extra features:
472 @example
473 avconv -i input.wav -write_xing 0 -id3v2_version 0 out.mp3
474 @end example
476 @section ogg
478 Ogg container muxer.
480 @table @option
481 @item -page_duration @var{duration}
482 Preferred page duration, in microseconds. The muxer will attempt to create
483 pages that are approximately @var{duration} microseconds long. This allows the
484 user to compromise between seek granularity and container overhead. The default
485 is 1 second. A value of 0 will fill all segments, making pages as large as
486 possible. A value of 1 will effectively use 1 packet-per-page in most
487 situations, giving a small seek granularity at the cost of additional container
488 overhead.
489 @end table
491 @c man end MUXERS