4 Muxers are configured elements in FFmpeg which allow writing
5 multimedia streams to a particular type of file.
7 When you configure your FFmpeg 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 ff* tools will display the list of
19 A description of some of the currently available muxers follows.
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
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
38 ffmpeg -i INPUT -f crc out.crc
41 You can print the CRC to stdout with the command:
43 ffmpeg -i INPUT -f crc -
46 You can select the output format of each frame with @command{ffmpeg} 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:
51 ffmpeg -i INPUT -c:a pcm_u8 -c:v mpeg2video -f crc -
54 See also the @ref{framecrc} muxer.
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
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}:
74 ffmpeg -i INPUT -f framecrc out.crc
77 You can print the CRC of each decoded frame to stdout with the command:
79 ffmpeg -i INPUT -f framecrc -
82 You can select the output format of each frame with @command{ffmpeg} 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:
88 ffmpeg -i INPUT -c:a pcm_u8 -c:v mpeg2video -f framecrc -
91 See also the @ref{crc} muxer.
98 The image file muxer writes video frames to image files.
100 The output filenames are specified by a pattern, which can be used to
101 produce sequentially numbered series of files.
102 The pattern may contain the string "%d" or "%0@var{N}d", this string
103 specifies the position of the characters representing a numbering in
104 the filenames. If the form "%0@var{N}d" is used, the string
105 representing the number in each filename is 0-padded to @var{N}
106 digits. The literal character '%' can be specified in the pattern with
109 If the pattern contains "%d" or "%0@var{N}d", the first filename of
110 the file list specified will contain the number 1, all the following
111 numbers will be sequential.
113 The pattern may contain a suffix which is used to automatically
114 determine the format of the image files to write.
116 For example the pattern "img-%03d.bmp" will specify a sequence of
117 filenames of the form @file{img-001.bmp}, @file{img-002.bmp}, ...,
118 @file{img-010.bmp}, etc.
119 The pattern "img%%-%d.jpg" will specify a sequence of filenames of the
120 form @file{img%-1.jpg}, @file{img%-2.jpg}, ..., @file{img%-10.jpg},
123 The following example shows how to use @command{ffmpeg} for creating a
124 sequence of files @file{img-001.jpeg}, @file{img-002.jpeg}, ...,
125 taking one image every second from the input video:
127 ffmpeg -i in.avi -vsync 1 -r 1 -f image2 'img-%03d.jpeg'
130 Note that with @command{ffmpeg}, if the format is not specified with the
131 @code{-f} option and the output filename specifies an image file
132 format, the image2 muxer is automatically selected, so the previous
133 command can be written as:
135 ffmpeg -i in.avi -vsync 1 -r 1 'img-%03d.jpeg'
138 Note also that the pattern must not necessarily contain "%d" or
139 "%0@var{N}d", for example to create a single image file
140 @file{img.jpeg} from the input video you can employ the command:
142 ffmpeg -i in.avi -f image2 -frames:v 1 img.jpeg
145 The image muxer supports the .Y.U.V image file format. This format is
146 special in that that each image frame consists of three files, for
147 each of the YUV420P components. To read or write this image file format,
148 specify the name of the '.Y' file. The muxer will automatically open the
149 '.U' and '.V' files as required.
151 @section MOV/MP4/ISMV
153 The mov/mp4/ismv muxer supports fragmentation. Normally, a MOV/MP4
154 file has all the metadata about all packets stored in one location
155 (written at the end of the file, it can be moved to the start for
156 better playback using the @command{qt-faststart} tool). A fragmented
157 file consists of a number of fragments, where packets and metadata
158 about these packets are stored together. Writing a fragmented
159 file has the advantage that the file is decodable even if the
160 writing is interrupted (while a normal MOV/MP4 is undecodable if
161 it is not properly finished), and it requires less memory when writing
162 very long files (since writing normal MOV/MP4 files stores info about
163 every single packet in memory until the file is closed). The downside
164 is that it is less compatible with other applications.
166 Fragmentation is enabled by setting one of the AVOptions that define
167 how to cut the file into fragments:
170 @item -moov_size @var{bytes}
171 Reserves space for the moov atom at the beginning of the file instead of placing the
172 moov atom at the end. If the space reserved is insufficient, muxing will fail.
173 @item -movflags frag_keyframe
174 Start a new fragment at each video keyframe.
175 @item -frag_duration @var{duration}
176 Create fragments that are @var{duration} microseconds long.
177 @item -frag_size @var{size}
178 Create fragments that contain up to @var{size} bytes of payload data.
179 @item -movflags frag_custom
180 Allow the caller to manually choose when to cut fragments, by
181 calling @code{av_write_frame(ctx, NULL)} to write a fragment with
182 the packets written so far. (This is only useful with other
183 applications integrating libavformat, not from @command{ffmpeg}.)
184 @item -min_frag_duration @var{duration}
185 Don't create fragments that are shorter than @var{duration} microseconds long.
188 If more than one condition is specified, fragments are cut when
189 one of the specified conditions is fulfilled. The exception to this is
190 @code{-min_frag_duration}, which has to be fulfilled for any of the other
193 Additionally, the way the output file is written can be adjusted
194 through a few other options:
197 @item -movflags empty_moov
198 Write an initial moov atom directly at the start of the file, without
199 describing any samples in it. Generally, an mdat/moov pair is written
200 at the start of the file, as a normal MOV/MP4 file, containing only
201 a short portion of the file. With this option set, there is no initial
202 mdat atom, and the moov atom only describes the tracks but has
205 Files written with this option set do not work in QuickTime.
206 This option is implicitly set when writing ismv (Smooth Streaming) files.
207 @item -movflags separate_moof
208 Write a separate moof (movie fragment) atom for each track. Normally,
209 packets for all tracks are written in a moof atom (which is slightly
210 more efficient), but with this option set, the muxer writes one moof/mdat
211 pair for each track, making it easier to separate tracks.
213 This option is implicitly set when writing ismv (Smooth Streaming) files.
216 Smooth Streaming content can be pushed in real time to a publishing
217 point on IIS with this muxer. Example:
219 ffmpeg -re @var{<normal input/transcoding options>} -movflags isml+frag_keyframe -f ismv http://server/publishingpoint.isml/Streams(Encoder1)
224 MPEG transport stream muxer.
226 This muxer implements ISO 13818-1 and part of ETSI EN 300 468.
228 The muxer options are:
231 @item -mpegts_original_network_id @var{number}
232 Set the original_network_id (default 0x0001). This is unique identifier
233 of a network in DVB. Its main use is in the unique identification of a
234 service through the path Original_Network_ID, Transport_Stream_ID.
235 @item -mpegts_transport_stream_id @var{number}
236 Set the transport_stream_id (default 0x0001). This identifies a
238 @item -mpegts_service_id @var{number}
239 Set the service_id (default 0x0001) also known as program in DVB.
240 @item -mpegts_pmt_start_pid @var{number}
241 Set the first PID for PMT (default 0x1000, max 0x1f00).
242 @item -mpegts_start_pid @var{number}
243 Set the first PID for data packets (default 0x0100, max 0x0f00).
246 The recognized metadata settings in mpegts muxer are @code{service_provider}
247 and @code{service_name}. If they are not set the default for
248 @code{service_provider} is "FFmpeg" and the default for
249 @code{service_name} is "Service01".
252 ffmpeg -i file.mpg -c copy \
253 -mpegts_original_network_id 0x1122 \
254 -mpegts_transport_stream_id 0x3344 \
255 -mpegts_service_id 0x5566 \
256 -mpegts_pmt_start_pid 0x1500 \
257 -mpegts_start_pid 0x150 \
258 -metadata service_provider="Some provider" \
259 -metadata service_name="Some Channel" \
267 This muxer does not generate any output file, it is mainly useful for
268 testing or benchmarking purposes.
270 For example to benchmark decoding with @command{ffmpeg} you can use the
273 ffmpeg -benchmark -i INPUT -f null out.null
276 Note that the above command does not read or write the @file{out.null}
277 file, but specifying the output file is required by the @command{ffmpeg}
280 Alternatively you can write the command as:
282 ffmpeg -benchmark -i INPUT -f null -
287 Matroska container muxer.
289 This muxer implements the matroska and webm container specs.
291 The recognized metadata settings in this muxer are:
295 @item title=@var{title name}
296 Name provided to a single track
301 @item language=@var{language name}
302 Specifies the language of the track in the Matroska languages form
307 @item stereo_mode=@var{mode}
308 Stereo 3D video layout of two views in a single video track
313 Both views are arranged side by side, Left-eye view is on the left
315 Both views are arranged in top-bottom orientation, Left-eye view is at bottom
317 Both views are arranged in top-bottom orientation, Left-eye view is on top
318 @item checkerboard_rl
319 Each view is arranged in a checkerboard interleaved pattern, Left-eye view being first
320 @item checkerboard_lr
321 Each view is arranged in a checkerboard interleaved pattern, Right-eye view being first
322 @item row_interleaved_rl
323 Each view is constituted by a row based interleaving, Right-eye view is first row
324 @item row_interleaved_lr
325 Each view is constituted by a row based interleaving, Left-eye view is first row
326 @item col_interleaved_rl
327 Both views are arranged in a column based interleaving manner, Right-eye view is first column
328 @item col_interleaved_lr
329 Both views are arranged in a column based interleaving manner, Left-eye view is first column
330 @item anaglyph_cyan_red
331 All frames are in anaglyph format viewable through red-cyan filters
333 Both views are arranged side by side, Right-eye view is on the left
334 @item anaglyph_green_magenta
335 All frames are in anaglyph format viewable through green-magenta filters
337 Both eyes laced in one Block, Left-eye view is first
339 Both eyes laced in one Block, Right-eye view is first
343 For example a 3D WebM clip can be created using the following command line:
345 ffmpeg -i sample_left_right_clip.mpg -an -c:v libvpx -metadata stereo_mode=left_right -y stereo_clip.webm
350 Basic stream segmenter.
352 The segmenter muxer outputs streams to a number of separate files of nearly
353 fixed duration. Output filename pattern can be set in a fashion similar to
356 Every segment starts with a video keyframe, if a video stream is present.
357 The segment muxer works best with a single constant frame rate video.
359 Optionally it can generate a flat list of the created segments, one segment
363 @item segment_format @var{format}
364 Override the inner container format, by default it is guessed by the filename
366 @item segment_time @var{t}
367 Set segment duration to @var{t} seconds.
368 @item segment_list @var{name}
369 Generate also a listfile named @var{name}.
370 @item segment_list_size @var{size}
371 Overwrite the listfile once it reaches @var{size} entries.
372 @item segment_wrap @var{limit}
373 Wrap around segment index once it reaches @var{limit}.
377 ffmpeg -i in.mkv -c copy -map 0 -f segment -list out.list out%03d.nut
382 The MP3 muxer writes a raw MP3 stream with an ID3v2 header at the beginning and
383 optionally an ID3v1 tag at the end. ID3v2.3 and ID3v2.4 are supported, the
384 @code{id3v2_version} option controls which one is used. The legacy ID3v1 tag is
385 not written by default, but may be enabled with the @code{write_id3v1} option.
387 For seekable output the muxer also writes a Xing frame at the beginning, which
388 contains the number of frames in the file. It is useful for computing duration
391 The muxer supports writing ID3v2 attached pictures (APIC frames). The pictures
392 are supplied to the muxer in form of a video stream with a single packet. There
393 can be any number of those streams, each will correspond to a single APIC frame.
394 The stream metadata tags @var{title} and @var{comment} map to APIC
395 @var{description} and @var{picture type} respectively. See
396 @url{http://id3.org/id3v2.4.0-frames} for allowed picture types.
398 Note that the APIC frames must be written at the beginning, so the muxer will
399 buffer the audio frames until it gets all the pictures. It is therefore advised
400 to provide the pictures as soon as possible to avoid excessive buffering.
404 Write an mp3 with an ID3v2.3 header and an ID3v1 footer:
406 ffmpeg -i INPUT -id3v2_version 3 -write_id3v1 1 out.mp3
409 Attach a picture to an mp3:
411 ffmpeg -i input.mp3 -i cover.png -c copy -metadata:s:v title="Album cover"
412 -metadata:s:v comment="Cover (Front)" out.mp3