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 Audio Interchange File Format muxer.
26 It accepts the following options:
30 Enable ID3v2 tags writing when set to 1. Default is 0 (disabled).
33 Select ID3v2 version to write. Currently only version 3 and 4 (aka.
34 ID3v2.3 and ID3v2.4) are supported. The default is version 4.
41 CRC (Cyclic Redundancy Check) testing format.
43 This muxer computes and prints the Adler-32 CRC of all the input audio
44 and video frames. By default audio frames are converted to signed
45 16-bit raw audio and video frames to raw video before computing the
48 The output of the muxer consists of a single line of the form:
49 CRC=0x@var{CRC}, where @var{CRC} is a hexadecimal number 0-padded to
50 8 digits containing the CRC for all the decoded input frames.
52 For example to compute the CRC of the input, and store it in the file
55 ffmpeg -i INPUT -f crc out.crc
58 You can print the CRC to stdout with the command:
60 ffmpeg -i INPUT -f crc -
63 You can select the output format of each frame with @command{ffmpeg} by
64 specifying the audio and video codec and format. For example to
65 compute the CRC of the input audio converted to PCM unsigned 8-bit
66 and the input video converted to MPEG-2 video, use the command:
68 ffmpeg -i INPUT -c:a pcm_u8 -c:v mpeg2video -f crc -
71 See also the @ref{framecrc} muxer.
76 Per-packet CRC (Cyclic Redundancy Check) testing format.
78 This muxer computes and prints the Adler-32 CRC for each audio
79 and video packet. By default audio frames are converted to signed
80 16-bit raw audio and video frames to raw video before computing the
83 The output of the muxer consists of a line for each audio and video
86 @var{stream_index}, @var{packet_dts}, @var{packet_pts}, @var{packet_duration}, @var{packet_size}, 0x@var{CRC}
89 @var{CRC} is a hexadecimal number 0-padded to 8 digits containing the
92 For example to compute the CRC of the audio and video frames in
93 @file{INPUT}, converted to raw audio and video packets, and store it
94 in the file @file{out.crc}:
96 ffmpeg -i INPUT -f framecrc out.crc
99 To print the information to stdout, use the command:
101 ffmpeg -i INPUT -f framecrc -
104 With @command{ffmpeg}, you can select the output format to which the
105 audio and video frames are encoded before computing the CRC for each
106 packet by specifying the audio and video codec. For example, to
107 compute the CRC of each decoded input audio frame converted to PCM
108 unsigned 8-bit and of each decoded input video frame converted to
109 MPEG-2 video, use the command:
111 ffmpeg -i INPUT -c:a pcm_u8 -c:v mpeg2video -f framecrc -
114 See also the @ref{crc} muxer.
119 Per-packet MD5 testing format.
121 This muxer computes and prints the MD5 hash for each audio
122 and video packet. By default audio frames are converted to signed
123 16-bit raw audio and video frames to raw video before computing the
126 The output of the muxer consists of a line for each audio and video
129 @var{stream_index}, @var{packet_dts}, @var{packet_pts}, @var{packet_duration}, @var{packet_size}, @var{MD5}
132 @var{MD5} is a hexadecimal number representing the computed MD5 hash
135 For example to compute the MD5 of the audio and video frames in
136 @file{INPUT}, converted to raw audio and video packets, and store it
137 in the file @file{out.md5}:
139 ffmpeg -i INPUT -f framemd5 out.md5
142 To print the information to stdout, use the command:
144 ffmpeg -i INPUT -f framemd5 -
147 See also the @ref{md5} muxer.
154 It accepts the following options:
158 Set the number of times to loop the output. Use @code{-1} for no loop, @code{0}
159 for looping indefinitely (default).
162 Force the delay (expressed in centiseconds) after the last frame. Each frame
163 ends with a delay until the next frame. The default is @code{-1}, which is a
164 special value to tell the muxer to re-use the previous delay. In case of a
165 loop, you might want to customize this value to mark a pause for instance.
168 For example, to encode a gif looping 10 times, with a 5 seconds delay between
171 ffmpeg -i INPUT -loop 10 -final_delay 500 out.gif
174 Note 1: if you wish to extract the frames in separate GIF files, you need to
175 force the @ref{image2} muxer:
177 ffmpeg -i INPUT -c:v gif -f image2 "out%d.gif"
180 Note 2: the GIF format has a very small time base: the delay between two frames
181 can not be smaller than one centi second.
186 Apple HTTP Live Streaming muxer that segments MPEG-TS according to
187 the HTTP Live Streaming (HLS) specification.
189 It creates a playlist file and numbered segment files. The output
190 filename specifies the playlist filename; the segment filenames
191 receive the same basename as the playlist, a sequential number and
194 For example, to convert an input file with @command{ffmpeg}:
196 ffmpeg -i in.nut out.m3u8
199 See also the @ref{segment} muxer, which provides a more generic and
200 flexible implementation of a segmenter, and can be used to perform HLS
203 This muxer supports the following options:
206 @item hls_time @var{seconds}
207 Set the segment length in seconds. Default value is 2.
209 @item hls_list_size @var{size}
210 Set the maximum number of playlist entries. If set to 0 the list file
211 will contain all the segments. Default value is 5.
213 @item hls_wrap @var{wrap}
214 Set the number after which the segment filename number (the number
215 specified in each segment file) wraps. If set to 0 the number will be
216 never wrapped. Default value is 0.
218 This option is useful to avoid to fill the disk with many segment
219 files, and limits the maximum number of segment files written to disk
222 @item start_number @var{number}
223 Start the playlist sequence number from @var{number}. Default value is
226 Note that the playlist sequence number must be unique for each segment
227 and it is not to be confused with the segment filename sequence number
228 which can be cyclic, for example if the @option{wrap} option is
237 Microsoft's icon file format (ICO) has some strict limitations that should be noted:
241 Size cannot exceed 256 pixels in any dimension
244 Only BMP and PNG images can be stored
247 If a BMP image is used, it must be one of the following pixel formats:
249 BMP Bit Depth FFmpeg Pixel Format
259 If a BMP image is used, it must use the BITMAPINFOHEADER DIB header
262 If a PNG image is used, it must use the rgba pixel format
270 The image file muxer writes video frames to image files.
272 The output filenames are specified by a pattern, which can be used to
273 produce sequentially numbered series of files.
274 The pattern may contain the string "%d" or "%0@var{N}d", this string
275 specifies the position of the characters representing a numbering in
276 the filenames. If the form "%0@var{N}d" is used, the string
277 representing the number in each filename is 0-padded to @var{N}
278 digits. The literal character '%' can be specified in the pattern with
281 If the pattern contains "%d" or "%0@var{N}d", the first filename of
282 the file list specified will contain the number 1, all the following
283 numbers will be sequential.
285 The pattern may contain a suffix which is used to automatically
286 determine the format of the image files to write.
288 For example the pattern "img-%03d.bmp" will specify a sequence of
289 filenames of the form @file{img-001.bmp}, @file{img-002.bmp}, ...,
290 @file{img-010.bmp}, etc.
291 The pattern "img%%-%d.jpg" will specify a sequence of filenames of the
292 form @file{img%-1.jpg}, @file{img%-2.jpg}, ..., @file{img%-10.jpg},
295 The following example shows how to use @command{ffmpeg} for creating a
296 sequence of files @file{img-001.jpeg}, @file{img-002.jpeg}, ...,
297 taking one image every second from the input video:
299 ffmpeg -i in.avi -vsync 1 -r 1 -f image2 'img-%03d.jpeg'
302 Note that with @command{ffmpeg}, if the format is not specified with the
303 @code{-f} option and the output filename specifies an image file
304 format, the image2 muxer is automatically selected, so the previous
305 command can be written as:
307 ffmpeg -i in.avi -vsync 1 -r 1 'img-%03d.jpeg'
310 Note also that the pattern must not necessarily contain "%d" or
311 "%0@var{N}d", for example to create a single image file
312 @file{img.jpeg} from the input video you can employ the command:
314 ffmpeg -i in.avi -f image2 -frames:v 1 img.jpeg
318 @item start_number @var{number}
319 Start the sequence from @var{number}. Default value is 1. Must be a
322 @item -update @var{number}
323 If @var{number} is nonzero, the filename will always be interpreted as just a
324 filename, not a pattern, and this file will be continuously overwritten with new
329 The image muxer supports the .Y.U.V image file format. This format is
330 special in that that each image frame consists of three files, for
331 each of the YUV420P components. To read or write this image file format,
332 specify the name of the '.Y' file. The muxer will automatically open the
333 '.U' and '.V' files as required.
337 Matroska container muxer.
339 This muxer implements the matroska and webm container specs.
341 The recognized metadata settings in this muxer are:
345 Set title name provided to a single track.
348 Specify the language of the track in the Matroska languages form.
351 Set stereo 3D video layout of two views in a single video track.
353 The following values are recognized:
358 Both views are arranged side by side, Left-eye view is on the left
360 Both views are arranged in top-bottom orientation, Left-eye view is at bottom
362 Both views are arranged in top-bottom orientation, Left-eye view is on top
363 @item checkerboard_rl
364 Each view is arranged in a checkerboard interleaved pattern, Left-eye view being first
365 @item checkerboard_lr
366 Each view is arranged in a checkerboard interleaved pattern, Right-eye view being first
367 @item row_interleaved_rl
368 Each view is constituted by a row based interleaving, Right-eye view is first row
369 @item row_interleaved_lr
370 Each view is constituted by a row based interleaving, Left-eye view is first row
371 @item col_interleaved_rl
372 Both views are arranged in a column based interleaving manner, Right-eye view is first column
373 @item col_interleaved_lr
374 Both views are arranged in a column based interleaving manner, Left-eye view is first column
375 @item anaglyph_cyan_red
376 All frames are in anaglyph format viewable through red-cyan filters
378 Both views are arranged side by side, Right-eye view is on the left
379 @item anaglyph_green_magenta
380 All frames are in anaglyph format viewable through green-magenta filters
382 Both eyes laced in one Block, Left-eye view is first
384 Both eyes laced in one Block, Right-eye view is first
388 For example a 3D WebM clip can be created using the following command line:
390 ffmpeg -i sample_left_right_clip.mpg -an -c:v libvpx -metadata stereo_mode=left_right -y stereo_clip.webm
393 This muxer supports the following options:
396 @item reserve_index_space
397 By default, this muxer writes the index for seeking (called cues in Matroska
398 terms) at the end of the file, because it cannot know in advance how much space
399 to leave for the index at the beginning of the file. However for some use cases
400 -- e.g. streaming where seeking is possible but slow -- it is useful to put the
401 index at the beginning of the file.
403 If this option is set to a non-zero value, the muxer will reserve a given amount
404 of space in the file header and then try to write the cues there when the muxing
405 finishes. If the available space does not suffice, muxing will fail. A safe size
406 for most use cases should be about 50kB per hour of video.
408 Note that cues are only written if the output is seekable and this option will
409 have no effect if it is not.
417 This muxer computes and prints the MD5 hash of all the input audio
418 and video frames. By default audio frames are converted to signed
419 16-bit raw audio and video frames to raw video before computing the
422 The output of the muxer consists of a single line of the form:
423 MD5=@var{MD5}, where @var{MD5} is a hexadecimal number representing
424 the computed MD5 hash.
426 For example to compute the MD5 hash of the input converted to raw
427 audio and video, and store it in the file @file{out.md5}:
429 ffmpeg -i INPUT -f md5 out.md5
432 You can print the MD5 to stdout with the command:
434 ffmpeg -i INPUT -f md5 -
437 See also the @ref{framemd5} muxer.
439 @section mov/mp4/ismv
441 MOV/MP4/ISMV (Smooth Streaming) muxer.
443 The mov/mp4/ismv muxer supports fragmentation. Normally, a MOV/MP4
444 file has all the metadata about all packets stored in one location
445 (written at the end of the file, it can be moved to the start for
446 better playback by adding @var{faststart} to the @var{movflags}, or
447 using the @command{qt-faststart} tool). A fragmented
448 file consists of a number of fragments, where packets and metadata
449 about these packets are stored together. Writing a fragmented
450 file has the advantage that the file is decodable even if the
451 writing is interrupted (while a normal MOV/MP4 is undecodable if
452 it is not properly finished), and it requires less memory when writing
453 very long files (since writing normal MOV/MP4 files stores info about
454 every single packet in memory until the file is closed). The downside
455 is that it is less compatible with other applications.
457 Fragmentation is enabled by setting one of the AVOptions that define
458 how to cut the file into fragments:
461 @item -moov_size @var{bytes}
462 Reserves space for the moov atom at the beginning of the file instead of placing the
463 moov atom at the end. If the space reserved is insufficient, muxing will fail.
464 @item -movflags frag_keyframe
465 Start a new fragment at each video keyframe.
466 @item -frag_duration @var{duration}
467 Create fragments that are @var{duration} microseconds long.
468 @item -frag_size @var{size}
469 Create fragments that contain up to @var{size} bytes of payload data.
470 @item -movflags frag_custom
471 Allow the caller to manually choose when to cut fragments, by
472 calling @code{av_write_frame(ctx, NULL)} to write a fragment with
473 the packets written so far. (This is only useful with other
474 applications integrating libavformat, not from @command{ffmpeg}.)
475 @item -min_frag_duration @var{duration}
476 Don't create fragments that are shorter than @var{duration} microseconds long.
479 If more than one condition is specified, fragments are cut when
480 one of the specified conditions is fulfilled. The exception to this is
481 @code{-min_frag_duration}, which has to be fulfilled for any of the other
484 Additionally, the way the output file is written can be adjusted
485 through a few other options:
488 @item -movflags empty_moov
489 Write an initial moov atom directly at the start of the file, without
490 describing any samples in it. Generally, an mdat/moov pair is written
491 at the start of the file, as a normal MOV/MP4 file, containing only
492 a short portion of the file. With this option set, there is no initial
493 mdat atom, and the moov atom only describes the tracks but has
496 Files written with this option set do not work in QuickTime.
497 This option is implicitly set when writing ismv (Smooth Streaming) files.
498 @item -movflags separate_moof
499 Write a separate moof (movie fragment) atom for each track. Normally,
500 packets for all tracks are written in a moof atom (which is slightly
501 more efficient), but with this option set, the muxer writes one moof/mdat
502 pair for each track, making it easier to separate tracks.
504 This option is implicitly set when writing ismv (Smooth Streaming) files.
505 @item -movflags faststart
506 Run a second pass moving the index (moov atom) to the beginning of the file.
507 This operation can take a while, and will not work in various situations such
508 as fragmented output, thus it is not enabled by default.
509 @item -movflags rtphint
510 Add RTP hinting tracks to the output file.
513 Smooth Streaming content can be pushed in real time to a publishing
514 point on IIS with this muxer. Example:
516 ffmpeg -re @var{<normal input/transcoding options>} -movflags isml+frag_keyframe -f ismv http://server/publishingpoint.isml/Streams(Encoder1)
521 The MP3 muxer writes a raw MP3 stream with an ID3v2 header at the beginning and
522 optionally an ID3v1 tag at the end. ID3v2.3 and ID3v2.4 are supported, the
523 @code{id3v2_version} option controls which one is used. The legacy ID3v1 tag is
524 not written by default, but may be enabled with the @code{write_id3v1} option.
526 For seekable output the muxer also writes a Xing frame at the beginning, which
527 contains the number of frames in the file. It is useful for computing duration
530 The muxer supports writing ID3v2 attached pictures (APIC frames). The pictures
531 are supplied to the muxer in form of a video stream with a single packet. There
532 can be any number of those streams, each will correspond to a single APIC frame.
533 The stream metadata tags @var{title} and @var{comment} map to APIC
534 @var{description} and @var{picture type} respectively. See
535 @url{http://id3.org/id3v2.4.0-frames} for allowed picture types.
537 Note that the APIC frames must be written at the beginning, so the muxer will
538 buffer the audio frames until it gets all the pictures. It is therefore advised
539 to provide the pictures as soon as possible to avoid excessive buffering.
543 Write an mp3 with an ID3v2.3 header and an ID3v1 footer:
545 ffmpeg -i INPUT -id3v2_version 3 -write_id3v1 1 out.mp3
548 To attach a picture to an mp3 file select both the audio and the picture stream
551 ffmpeg -i input.mp3 -i cover.png -c copy -map 0 -map 1
552 -metadata:s:v title="Album cover" -metadata:s:v comment="Cover (Front)" out.mp3
557 MPEG transport stream muxer.
559 This muxer implements ISO 13818-1 and part of ETSI EN 300 468.
561 The muxer options are:
564 @item -mpegts_original_network_id @var{number}
565 Set the original_network_id (default 0x0001). This is unique identifier
566 of a network in DVB. Its main use is in the unique identification of a
567 service through the path Original_Network_ID, Transport_Stream_ID.
568 @item -mpegts_transport_stream_id @var{number}
569 Set the transport_stream_id (default 0x0001). This identifies a
571 @item -mpegts_service_id @var{number}
572 Set the service_id (default 0x0001) also known as program in DVB.
573 @item -mpegts_pmt_start_pid @var{number}
574 Set the first PID for PMT (default 0x1000, max 0x1f00).
575 @item -mpegts_start_pid @var{number}
576 Set the first PID for data packets (default 0x0100, max 0x0f00).
577 @item -mpegts_m2ts_mode @var{number}
578 Enable m2ts mode if set to 1. Default value is -1 which disables m2ts mode.
579 @item -muxrate @var{number}
581 @item -pes_payload_size @var{number}
582 Set minimum PES packet payload in bytes.
583 @item -mpegts_flags @var{flags}
584 Set flags (see below).
585 @item -mpegts_copyts @var{number}
586 Preserve original timestamps, if value is set to 1. Default value is -1, which
587 results in shifting timestamps so that they start from 0.
588 @item -tables_version @var{number}
589 Set PAT, PMT and SDT version (default 0, valid values are from 0 to 31, inclusively).
590 This option allows updating stream structure so that standard consumer may
591 detect the change. To do so, reopen output AVFormatContext (in case of API
592 usage) or restart ffmpeg instance, cyclically changing tables_version value:
594 ffmpeg -i source1.ts -codec copy -f mpegts -tables_version 0 udp://1.1.1.1:1111
595 ffmpeg -i source2.ts -codec copy -f mpegts -tables_version 1 udp://1.1.1.1:1111
597 ffmpeg -i source3.ts -codec copy -f mpegts -tables_version 31 udp://1.1.1.1:1111
598 ffmpeg -i source1.ts -codec copy -f mpegts -tables_version 0 udp://1.1.1.1:1111
599 ffmpeg -i source2.ts -codec copy -f mpegts -tables_version 1 udp://1.1.1.1:1111
604 Option mpegts_flags may take a set of such flags:
608 Reemit PAT/PMT before writing the next packet.
610 Use LATM packetization for AAC.
613 The recognized metadata settings in mpegts muxer are @code{service_provider}
614 and @code{service_name}. If they are not set the default for
615 @code{service_provider} is "FFmpeg" and the default for
616 @code{service_name} is "Service01".
619 ffmpeg -i file.mpg -c copy \
620 -mpegts_original_network_id 0x1122 \
621 -mpegts_transport_stream_id 0x3344 \
622 -mpegts_service_id 0x5566 \
623 -mpegts_pmt_start_pid 0x1500 \
624 -mpegts_start_pid 0x150 \
625 -metadata service_provider="Some provider" \
626 -metadata service_name="Some Channel" \
634 This muxer does not generate any output file, it is mainly useful for
635 testing or benchmarking purposes.
637 For example to benchmark decoding with @command{ffmpeg} you can use the
640 ffmpeg -benchmark -i INPUT -f null out.null
643 Note that the above command does not read or write the @file{out.null}
644 file, but specifying the output file is required by the @command{ffmpeg}
647 Alternatively you can write the command as:
649 ffmpeg -benchmark -i INPUT -f null -
657 @item -page_duration @var{duration}
658 Preferred page duration, in microseconds. The muxer will attempt to create
659 pages that are approximately @var{duration} microseconds long. This allows the
660 user to compromise between seek granularity and container overhead. The default
661 is 1 second. A value of 0 will fill all segments, making pages as large as
662 possible. A value of 1 will effectively use 1 packet-per-page in most
663 situations, giving a small seek granularity at the cost of additional container
668 @section segment, stream_segment, ssegment
670 Basic stream segmenter.
672 This muxer outputs streams to a number of separate files of nearly
673 fixed duration. Output filename pattern can be set in a fashion similar to
676 @code{stream_segment} is a variant of the muxer used to write to
677 streaming output formats, i.e. which do not require global headers,
678 and is recommended for outputting e.g. to MPEG transport stream segments.
679 @code{ssegment} is a shorter alias for @code{stream_segment}.
681 Every segment starts with a keyframe of the selected reference stream,
682 which is set through the @option{reference_stream} option.
684 Note that if you want accurate splitting for a video file, you need to
685 make the input key frames correspond to the exact splitting times
686 expected by the segmenter, or the segment muxer will start the new
687 segment with the key frame found next after the specified start
690 The segment muxer works best with a single constant frame rate video.
692 Optionally it can generate a list of the created segments, by setting
693 the option @var{segment_list}. The list type is specified by the
694 @var{segment_list_type} option. The entry filenames in the segment
695 list are set by default to the basename of the corresponding segment
698 See also the @ref{hls} muxer, which provides a more specific
699 implementation for HLS segmentation.
701 The segment muxer supports the following options:
704 @item reference_stream @var{specifier}
705 Set the reference stream, as specified by the string @var{specifier}.
706 If @var{specifier} is set to @code{auto}, the reference is choosen
707 automatically. Otherwise it must be a stream specifier (see the ``Stream
708 specifiers'' chapter in the ffmpeg manual) which specifies the
709 reference stream. The default value is @code{auto}.
711 @item segment_format @var{format}
712 Override the inner container format, by default it is guessed by the filename
715 @item segment_list @var{name}
716 Generate also a listfile named @var{name}. If not specified no
717 listfile is generated.
719 @item segment_list_flags @var{flags}
720 Set flags affecting the segment list generation.
722 It currently supports the following flags:
725 Allow caching (only affects M3U8 list files).
728 Allow live-friendly file generation.
731 @item segment_list_size @var{size}
732 Update the list file so that it contains at most the last @var{size}
733 segments. If 0 the list file will contain all the segments. Default
736 @item segment_list_entry_prefix @var{prefix}
737 Set @var{prefix} to prepend to the name of each entry filename. By
738 default no prefix is applied.
740 @item segment_list_type @var{type}
741 Specify the format for the segment list file.
743 The following values are recognized:
746 Generate a flat list for the created segments, one segment per line.
749 Generate a list for the created segments, one segment per line,
750 each line matching the format (comma-separated values):
752 @var{segment_filename},@var{segment_start_time},@var{segment_end_time}
755 @var{segment_filename} is the name of the output file generated by the
756 muxer according to the provided pattern. CSV escaping (according to
757 RFC4180) is applied if required.
759 @var{segment_start_time} and @var{segment_end_time} specify
760 the segment start and end time expressed in seconds.
762 A list file with the suffix @code{".csv"} or @code{".ext"} will
763 auto-select this format.
765 @samp{ext} is deprecated in favor or @samp{csv}.
768 Generate an ffconcat file for the created segments. The resulting file
769 can be read using the FFmpeg @ref{concat} demuxer.
771 A list file with the suffix @code{".ffcat"} or @code{".ffconcat"} will
772 auto-select this format.
775 Generate an extended M3U8 file, version 3, compliant with
776 @url{http://tools.ietf.org/id/draft-pantos-http-live-streaming}.
778 A list file with the suffix @code{".m3u8"} will auto-select this format.
781 If not specified the type is guessed from the list file name suffix.
783 @item segment_time @var{time}
784 Set segment duration to @var{time}, the value must be a duration
785 specification. Default value is "2". See also the
786 @option{segment_times} option.
788 Note that splitting may not be accurate, unless you force the
789 reference stream key-frames at the given time. See the introductory
790 notice and the examples below.
792 @item segment_time_delta @var{delta}
793 Specify the accuracy time when selecting the start time for a
794 segment, expressed as a duration specification. Default value is "0".
796 When delta is specified a key-frame will start a new segment if its
797 PTS satisfies the relation:
799 PTS >= start_time - time_delta
802 This option is useful when splitting video content, which is always
803 split at GOP boundaries, in case a key frame is found just before the
804 specified split time.
806 In particular may be used in combination with the @file{ffmpeg} option
807 @var{force_key_frames}. The key frame times specified by
808 @var{force_key_frames} may not be set accurately because of rounding
809 issues, with the consequence that a key frame time may result set just
810 before the specified time. For constant frame rate videos a value of
811 1/2*@var{frame_rate} should address the worst case mismatch between
812 the specified time and the time set by @var{force_key_frames}.
814 @item segment_times @var{times}
815 Specify a list of split points. @var{times} contains a list of comma
816 separated duration specifications, in increasing order. See also
817 the @option{segment_time} option.
819 @item segment_frames @var{frames}
820 Specify a list of split video frame numbers. @var{frames} contains a
821 list of comma separated integer numbers, in increasing order.
823 This option specifies to start a new segment whenever a reference
824 stream key frame is found and the sequential number (starting from 0)
825 of the frame is greater or equal to the next value in the list.
827 @item segment_wrap @var{limit}
828 Wrap around segment index once it reaches @var{limit}.
830 @item segment_start_number @var{number}
831 Set the sequence number of the first segment. Defaults to @code{0}.
833 @item reset_timestamps @var{1|0}
834 Reset timestamps at the begin of each segment, so that each segment
835 will start with near-zero timestamps. It is meant to ease the playback
836 of the generated segments. May not work with some combinations of
837 muxers/codecs. It is set to @code{0} by default.
839 @item initial_offset @var{offset}
840 Specify timestamp offset to apply to the output packet timestamps. The
841 argument must be a time duration specification, and defaults to 0.
848 To remux the content of file @file{in.mkv} to a list of segments
849 @file{out-000.nut}, @file{out-001.nut}, etc., and write the list of
850 generated segments to @file{out.list}:
852 ffmpeg -i in.mkv -codec copy -map 0 -f segment -segment_list out.list out%03d.nut
856 As the example above, but segment the input file according to the split
857 points specified by the @var{segment_times} option:
859 ffmpeg -i in.mkv -codec copy -map 0 -f segment -segment_list out.csv -segment_times 1,2,3,5,8,13,21 out%03d.nut
863 As the example above, but use the @command{ffmpeg} @option{force_key_frames}
864 option to force key frames in the input at the specified location, together
865 with the segment option @option{segment_time_delta} to account for
866 possible roundings operated when setting key frame times.
868 ffmpeg -i in.mkv -force_key_frames 1,2,3,5,8,13,21 -codec:v mpeg4 -codec:a pcm_s16le -map 0 \
869 -f segment -segment_list out.csv -segment_times 1,2,3,5,8,13,21 -segment_time_delta 0.05 out%03d.nut
871 In order to force key frames on the input file, transcoding is
875 Segment the input file by splitting the input file according to the
876 frame numbers sequence specified with the @option{segment_frames} option:
878 ffmpeg -i in.mkv -codec copy -map 0 -f segment -segment_list out.csv -segment_frames 100,200,300,500,800 out%03d.nut
882 To convert the @file{in.mkv} to TS segments using the @code{libx264}
883 and @code{libfaac} encoders:
885 ffmpeg -i in.mkv -map 0 -codec:v libx264 -codec:a libfaac -f ssegment -segment_list out.list out%03d.ts
889 Segment the input file, and create an M3U8 live playlist (can be used
892 ffmpeg -re -i in.mkv -codec copy -map 0 -f segment -segment_list playlist.m3u8 \
893 -segment_list_flags +live -segment_time 10 out%03d.mkv
899 The tee muxer can be used to write the same data to several files or any
900 other kind of muxer. It can be used, for example, to both stream a video to
901 the network and save it to disk at the same time.
903 It is different from specifying several outputs to the @command{ffmpeg}
904 command-line tool because the audio and video data will be encoded only once
905 with the tee muxer; encoding can be a very expensive process. It is not
906 useful when using the libavformat API directly because it is then possible
907 to feed the same packets to several muxers directly.
909 The slave outputs are specified in the file name given to the muxer,
910 separated by '|'. If any of the slave name contains the '|' separator,
911 leading or trailing spaces or any special character, it must be
912 escaped (see @ref{quoting_and_escaping,,the "Quoting and escaping"
913 section in the ffmpeg-utils(1) manual,ffmpeg-utils}).
915 Muxer options can be specified for each slave by prepending them as a list of
916 @var{key}=@var{value} pairs separated by ':', between square brackets. If
917 the options values contain a special character or the ':' separator, they
918 must be escaped; note that this is a second level escaping.
920 The following special options are also recognized:
923 Specify the format name. Useful if it cannot be guessed from the
926 @item bsfs[/@var{spec}]
927 Specify a list of bitstream filters to apply to the specified
930 It is possible to specify to which streams a given bitstream filter
931 applies, by appending a stream specifier to the option separated by
932 @code{/}. @var{spec} must be a stream specifier (see @ref{Format
933 stream specifiers}). If the stream specifier is not specified, the
934 bistream filters will be applied to all streams in the output.
936 Several bitstream filters can be specified, separated by ",".
939 Select the streams that should be mapped to the slave output,
940 specified by a stream specifier. If not specified, this defaults to
941 all the input streams.
944 Some examples follow.
947 Encode something and both archive it in a WebM file and stream it
948 as MPEG-TS over UDP (the streams need to be explicitly mapped):
950 ffmpeg -i ... -c:v libx264 -c:a mp2 -f tee -map 0:v -map 0:a
951 "archive-20121107.mkv|[f=mpegts]udp://10.0.1.255:1234/"
955 Use @command{ffmpeg} to encode the input, and send the output
956 to three different destinations. The @code{dump_extra} bitstream
957 filter is used to add extradata information to all the output video
958 keyframes packets, as requested by the MPEG-TS format. The select
959 option is applied to @file{out.aac} in order to make it contain only
962 ffmpeg -i ... -map 0 -flags +global_header -c:v libx264 -c:a aac -strict experimental
963 -f tee "[bsfs/v=dump_extra]out.ts|[movflags=+faststart]out.mp4|[select=a]out.aac"
967 As below, but select only stream @code{a:1} for the audio output. Note
968 that a second level escaping must be performed, as ":" is a special
969 character used to separate options.
971 ffmpeg -i ... -map 0 -flags +global_header -c:v libx264 -c:a aac -strict experimental
972 -f tee "[bsfs/v=dump_extra]out.ts|[movflags=+faststart]out.mp4|[select=\'a:1\']out.aac"
976 Note: some codecs may need different options depending on the output format;
977 the auto-detection of this can not work with the tee muxer. The main example
978 is the @option{global_header} flag.