[FFmpeg-devel] [PATCH 1/2] doc/muxers: extend documentation for MOV muxers

Sat Jan 6 22:43:47 EET 2024

+This section covers formats belonging to the QuickTime / MOV family,
+also named after the MPEG-4 Part 14 format, also named after the ISO
+base media file format (ISOBMFF).
+
+The MOV format was originally developed for the Apple QuickTime
+container format. Then it was later used as basis for the MPEG MPEG-4
+Part 1 (later Part 14) format, also named after ISO/IEC 14496-1.
+
+The format was later generalized into the ISO base media file format,
+also named MPEG-4 Part 12 format or ISO/IEC 14496-12 or ISO/IEC
+15444-12.
+

The word "also" is very prominent in this part (and a duplicate MPEG).  I
admit it feels confusing to read. Maybe something like this?

This section covers formats belonging to the QuickTime / MOV family,
including the MPEG-4 Part 14 format. These formats share a common structure
based on the ISO base media file format (ISOBMFF). ISOBMFF is also known as
MPEG-4 Part 12, ISO/IEC 14496-12, or ISO/IEC 15444-12.

The MOV format was originally developed for use with Apple QuickTime.
It was later used as the basis for MPEG-4 Part 1 (later Part 14), also
known as
ISO/IEC 14496-1. That format was then generalized into ISOBMFF.

Thank you!

On Sat, Jan 6, 2024 at 10:52 AM Stefano Sabatini <stefasab at gmail.com> wrote:

> ---
>  doc/muxers.texi | 468 +++++++++++++++++++++++++++++++++---------------
>  1 file changed, 321 insertions(+), 147 deletions(-)
>
> diff --git a/doc/muxers.texi b/doc/muxers.texi
> index 7b705b6a9e..345a55e8f4 100644
> --- a/doc/muxers.texi
> +++ b/doc/muxers.texi
> @@ -19,6 +19,327 @@ enabled demuxers and muxers.
>
>  A description of some of the currently available muxers follows.
>
> + at section 3gp, 3g2, f4v, ipod, ismv, mov, mp4, psp
> +
> +MOV/MPEG-4/ISOMBFF format family muxers.
> +
> +This section covers formats belonging to the QuickTime / MOV family,
> +also named after the MPEG-4 Part 14 format, also named after the ISO
> +base media file format (ISOBMFF).
> +
> +The MOV format was originally developed for the Apple QuickTime
> +container format. Then it was later used as basis for the MPEG MPEG-4
> +Part 1 (later Part 14) format, also named after ISO/IEC 14496-1.
> +
> +The format was later generalized into the ISO base media file format,
> +also named MPEG-4 Part 12 format or ISO/IEC 14496-12 or ISO/IEC
> +15444-12.
> +
> +It comprises the following muxers:
> +
> + at table @samp
> + at item 3gp
> +Third Generation Partnership Project (3GPP) format for 3G UMTS
> +multimedia services.
> +
> + at item 3g2
> +Third Generation Partnership Project 2 (3GP2 or 3GPP2) format for 3G
> +CDMA2000 multimedia services, similar to @code{3gp} with extensions
> +and limitations
> +
> + at item f4v
> +Adobe Flash Video format.
> +
> + at item ipod
> +MPEG4 file formation audio file, as MOV/MP4 but limited to contain
> +only audio streams, typically played with the Apple ipod device
> +
> + at item ismv
> +Microsoft IIS (Internet Information Services) Smooth Streaming
> +Audio/Video (ISMV or ISMA) format. This is based on MPEG-4 Part 14
> +format with a few incompatible variants, used to stream media files
> +for the Microsoft IIS server.
> +
> + at item mov
> +A QuickTime format identified by the @code{.mov} extension, used
> +natively by Apple QuickTime player.
> +
> + at item mp4
> +MP4 or MPEG-4 Part 14 format.
> +
> + at item psp
> +PlayStation Portable MP4/MPEG-4 Part 14 format variant. This is based
> +on MPEG-4 Part 14 format with a few incompatible variants, used to
> +play files on PlayStation devices.
> + at end table
> +
> + at subsection Fragmentation
> +
> +The @samp{mov}, @samp{mp4}, and @samp{ismv} muxers support
> +fragmentation. Normally, a MOV/MP4 file has all the metadata about all
> +packets stored in one location.
> +
> +This data is usually written at the end of the file, but it can be
> +moved to the start for better playback by adding @code{+faststart} to
> +the @code{-movflags}, or using the @command{qt-faststart} tool).
> +
> +A fragmented file consists of a number of fragments, where packets and
> +metadata about these packets are stored together. Writing a fragmented
> +file has the advantage that the file is decodable even if the writing
> +is interrupted (while a normal MOV/MP4 is undecodable if it is not
> +properly finished), and it requires less memory when writing very long
> +files (since writing normal MOV/MP4 files stores info about every
> +single packet in memory until the file is closed). The downside is
> +that it is less compatible with other applications.
> +
> +Fragmentation is enabled by setting one of the options that define
> +how to cut the file into fragments:
> + at table @option
> + at item frag_duration
> + at item frag_size
> + at item min_frag_duration
> + at item movflags +frag_keyframe
> + at item movflags +frag_custom
> + at end table
> +
> +If more than one condition is specified, fragments are cut when one of
> +the specified conditions is fulfilled. The exception to this is the
> +option @option{min_frag_duration}, which has to be fulfilled for any
> +of the other conditions to apply.
> +
> + at subsection Options
> +
> + at table @option
> +
> + at item brand @var{brand_string}
> +Override major brand.
> +
> + at item empty_hdlr_name @var{bool}
> +Enable to skip writing the name inside a @code{hdlr} box.
> +Default is @code{false}.
> +
> + at item encryption_key @var{key}
> +set the media encryption key in hexadecimal format
> +
> + at item encryption_kid @var{kid}
> +set the media encryption key identifier in hexadecimal format
> +
> + at item encryption_scheme @var{scheme}
> +configure the encryption scheme, allowed values are @samp{none}, and
> + at samp{cenc-aes-ctr}
> +
> + at item frag_duration @var{duration}
> +Create fragments that are @var{duration} microseconds long.
> +
> + at item frag_interleave  @var{number}
> +Interleave samples within fragments (max number of consecutive
> +samples, lower is tighter interleaving, but with more overhead. It is
> +set to @code{0} by default.
> +
> + at item frag_size @var{size}
> +create fragments that contain up to @var{size} bytes of payload data
> +
> + at item iods_audio_profile @var{profile}
> +specify iods number for the audio profile atom (from -1 to 255),
> +default is @code{-1}
> +
> + at item iods_video_profile @var{profile}
> +specify iods number for the video profile atom (from -1 to 255),
> +default is @code{-1}
> +
> + at item ism_lookahead @var{num_entries}
> +specify number of lookahead entries for ISM files (from 0 to 255),
> +default is @code{0}
> +
> + at item min_frag_duration @var{duration}
> +do not create fragments that are shorter than @var{duration} microseconds
> long
> +
> + at item moov_size @var{bytes}
> +Reserves space for the moov atom at the beginning of the file instead of
> placing the
> +moov atom at the end. If the space reserved is insufficient, muxing will
> fail.
> +
> + at item mov_gamma @var{gamma}
> +specify gamma value for gama atom (as a decimal number from 0 to 10),
> +default is @code{0.0}, must be set together with @code{+ movflags}
> +
> + at item movflags @var{flags}
> +Set various muxing switches. The following flags can be used:
> + at table @samp
> + at item cmaf
> +write CMAF (Common Media Application Format) compatible fragmented
> +MP4 output
> +
> + at item dash
> +write DASH (Dynamic Adaptive Streaming over HTTP) compatible fragmented
> +MP4 output
> +
> + at item default_base_moof
> +Similarly to the @samp{omit_tfhd_offset} flag, this flag avoids
> +writing the absolute base_data_offset field in tfhd atoms, but does so
> +by using the new default-base-is-moof flag instead. This flag is new
> +from 14496-12:2012. This may make the fragments easier to parse in
> +certain circumstances (avoiding basing track fragment location
> +calculations on the implicit end of the previous track fragment).
> +
> + at item delay_moov
> +delay writing the initial moov until the first fragment is cut, or
> +until the first fragment flush
> +
> + at item disable_chpl
> +Disable Nero chapter markers (chpl atom). Normally, both Nero chapters
> +and a QuickTime chapter track are written to the file. With this
> +option set, only the QuickTime chapter track will be written. Nero
> +chapters can cause failures when the file is reprocessed with certain
> +tagging programs, like mp3Tag 2.61a and iTunes 11.3, most likely other
> +versions are affected as well.
> +
> + at item faststart
> +Run a second pass moving the index (moov atom) to the beginning of the
> +file. This operation can take a while, and will not work in various
> +situations such as fragmented output, thus it is not enabled by
> +default.
> +
> + at item frag_custom
> +Allow the caller to manually choose when to cut fragments, by calling
> + at code{av_write_frame(ctx, NULL)} to write a fragment with the packets
> +written so far. (This is only useful with other applications
> +integrating libavformat, not from @command{ffmpeg}.)
> +
> + at item frag_discont
> +signal that the next fragment is discontinuous from earlier ones
> +
> + at item frag_every_frame
> +fragment at every frame
> +
> + at item frag_keyframe
> +start a new fragment at each video keyframe
> +
> + at item global_sidx
> +write a global sidx index at the start of the file
> +
> + at item isml
> +create a live smooth streaming feed (for pushing to a publishing point)
> +
> + at item negative_cts_offsets
> +Enables utilization of version 1 of the CTTS box, in which the CTS
> offsets can
> +be negative. This enables the initial sample to have DTS/CTS of zero, and
> +reduces the need for edit lists for some cases such as video tracks with
> +B-frames. Additionally, eases conformance with the DASH-IF
> interoperability
> +guidelines.
> +
> +This option is implicitly set when writing @samp{ismv} (Smooth
> +Streaming) files.
> +
> + at item omit_tfhd_offset
> +Do not write any absolute base_data_offset in tfhd atoms. This avoids
> +tying fragments to absolute byte positions in the file/streams.
> +
> + at item prefer_icc
> +If writing colr atom prioritise usage of ICC profile if it exists in
> +stream packet side data.
> +
> + at item rtphint
> +add RTP hinting tracks to the output file
> +
> + at item separate_moof
> +Write a separate moof (movie fragment) atom for each track. Normally,
> +packets for all tracks are written in a moof atom (which is slightly
> +more efficient), but with this option set, the muxer writes one
> +moof/mdat pair for each track, making it easier to separate tracks.
> +
> + at item skip_sidx
> +Skip writing of sidx atom. When bitrate overhead due to sidx atom is
> +high, this option could be used for cases where sidx atom is not
> +mandatory. When the @samp{global_sidx} flag is enabled, this option
> +is ignored.
> +
> + at item skip_trailer
> +skip writing the mfra/tfra/mfro trailer for fragmented files
> +
> + at item use_metadata_tags
> +use mdta atom for metadata
> +
> + at item write_colr
> +write colr atom even if the color info is unspecified. This flag is
> +experimental, may be renamed or changed, do not use from scripts.
> +
> + at item write_gama
> +write deprecated gama atom
> + at end table
> +
> + at item movie_timescale @var{scale}
> +Set the timescale written in the movie header box (@code{mvhd}).
> +Range is 1 to INT_MAX. Default is @code{1000}.
> +
> + at item rtpflags @var{flags}
> +Add RTP hinting tracks to the output file.
> +
> +The following flags can be used:
> + at table @samp
> + at item h264_mode0
> +use mode 0 for H.264 in RTP
> +
> + at item latm
> +use MP4A-LATM packetization instead of MPEG4-GENERIC for AAC
> +
> + at item rfc2190
> +use RFC 2190 packetization instead of RFC 4629 for H.263
> +
> + at item send_bye
> +send RTCP BYE packets when finishing
> +
> + at item skip_rtcp
> +do not send RTCP sender reports
> + at end table
> +
> + at item skip_iods @var{bool}
> +skip writing iods atom (default value is @code{true})
> +
> + at item use_editlist @var{bool}
> +use edit list (default value is @code{auto})
> +
> + at item use_stream_ids_as_track_ids
> +use stream ids as track ids (default value is @code{false})
> +
> + at item video_track_timescale @var{scale}
> +Set the timescale used for video tracks. Range is @code{0} to INT_MAX. If
> +set to @code{0}, the timescale is automatically set based on the
> +native stream time base. Default is @code{0}.
> +
> + at item write_btrt @var{bool}
> +Force or disable writing bitrate box inside stsd box of a track. The
> +box contains decoding buffer size (in bytes), maximum bitrate and
> +average bitrate for the track. The box will be skipped if none of
> +these values can be computed.  Default is @code{-1} or @code{auto},
> +which will write the box only in MP4 mode.
> +
> + at item write_prft @var{option}
> +Write producer time reference box (PRFT) with a specified time source for
> the
> +NTP field in the PRFT box. Set value as @samp{wallclock} to specify
> timesource
> +as wallclock time and @samp{pts} to specify timesource as input packets'
> PTS
> +values.
> +
> + at item write_tmcd @var{bool}
> +Specify @code{on} to force writing a timecode track, @code{off} to
> disable it
> +and @code{auto} to write a timecode track only for mov and mp4 output
> (default).
> +
> +Setting value to @samp{pts} is applicable only for a live encoding use
> case,
> +where PTS values are set as as wallclock time at the source. For example,
> an
> +encoding use case with decklink capture source where @option{video_pts}
> and
> + at option{audio_pts} are set to @samp{abs_wallclock}.
> + at end table
> +
> + at subsection Examples
> +
> + at itemize
> + at item
> +Push Smooth Streaming content in real time to a publishing point on
> +IIS with the @samp{ismv} muxer using @command{ffmpeg}:
> + at example
> +ffmpeg -re @var{<normal input/transcoding options>} -movflags
> isml+frag_keyframe -f ismv
> http://server/publishingpoint.isml/Streams(Encoder1)
> + at end example
> + at end itemize
> +
>  @anchor{a64}
>  @section a64
>
> @@ -1623,153 +1944,6 @@ ffmpeg -i INPUT -f md5 -
>
>  See also the @ref{hash} and @ref{framemd5} muxers.
>
> - at section mov, mp4, ismv
> -
> -MOV/MP4/ISMV (Smooth Streaming) muxer.
> -
> -The mov/mp4/ismv muxer supports fragmentation. Normally, a MOV/MP4
> -file has all the metadata about all packets stored in one location
> -(written at the end of the file, it can be moved to the start for
> -better playback by adding @code{+faststart} to the @code{-movflags}, or
> -using the @command{qt-faststart} tool).
> -
> -A fragmented
> -file consists of a number of fragments, where packets and metadata
> -about these packets are stored together. Writing a fragmented
> -file has the advantage that the file is decodable even if the
> -writing is interrupted (while a normal MOV/MP4 is undecodable if
> -it is not properly finished), and it requires less memory when writing
> -very long files (since writing normal MOV/MP4 files stores info about
> -every single packet in memory until the file is closed). The downside
> -is that it is less compatible with other applications.
> -
> -Fragmentation is enabled by setting one of the options that define
> -how to cut the file into fragments: @code{-frag_duration},
> @code{-frag_size},
> - at code{-min_frag_duration}, @code{-movflags +frag_keyframe} and
> - at code{-movflags +frag_custom}. If more than one condition is specified,
> -fragments are cut when one of the specified conditions is fulfilled. The
> -exception to this is @code{-min_frag_duration}, which has to be fulfilled
> for
> -any of the other conditions to apply.
> -
> - at subsection Options
> -
> - at table @option
> - at item frag_duration @var{duration}
> -Create fragments that are @var{duration} microseconds long.
> - at item frag_size @var{size}
> -Create fragments that contain up to @var{size} bytes of payload data.
> - at item min_frag_duration @var{duration}
> -Don't create fragments that are shorter than @var{duration} microseconds
> long.
> - at item movflags @var{flags}
> -Set various muxing switches. The following flags can be used:
> - at table @samp
> - at item frag_keyframe
> -Start a new fragment at each video keyframe.
> - at item frag_custom
> -Allow the caller to manually choose when to cut fragments, by
> -calling @code{av_write_frame(ctx, NULL)} to write a fragment with
> -the packets written so far. (This is only useful with other
> -applications integrating libavformat, not from @command{ffmpeg}.)
> - at item empty_moov
> -Write an initial moov atom directly at the start of the file, without
> -describing any samples in it. Generally, an mdat/moov pair is written
> -at the start of the file, as a normal MOV/MP4 file, containing only
> -a short portion of the file. With this option set, there is no initial
> -mdat atom, and the moov atom only describes the tracks but has
> -a zero duration.
> -
> -This option is implicitly set when writing ismv (Smooth Streaming) files.
> - at item separate_moof
> -Write a separate moof (movie fragment) atom for each track. Normally,
> -packets for all tracks are written in a moof atom (which is slightly
> -more efficient), but with this option set, the muxer writes one moof/mdat
> -pair for each track, making it easier to separate tracks.
> -
> -This option is implicitly set when writing ismv (Smooth Streaming) files.
> - at item skip_sidx
> -Skip writing of sidx atom. When bitrate overhead due to sidx atom is high,
> -this option could be used for cases where sidx atom is not mandatory.
> -When global_sidx flag is enabled, this option will be ignored.
> - at item faststart
> -Run a second pass moving the index (moov atom) to the beginning of the
> file.
> -This operation can take a while, and will not work in various situations
> such
> -as fragmented output, thus it is not enabled by default.
> - at item rtphint
> -Add RTP hinting tracks to the output file.
> - at item disable_chpl
> -Disable Nero chapter markers (chpl atom).  Normally, both Nero chapters
> -and a QuickTime chapter track are written to the file. With this option
> -set, only the QuickTime chapter track will be written. Nero chapters can
> -cause failures when the file is reprocessed with certain tagging
> programs, like
> -mp3Tag 2.61a and iTunes 11.3, most likely other versions are affected as
> well.
> - at item omit_tfhd_offset
> -Do not write any absolute base_data_offset in tfhd atoms. This avoids
> -tying fragments to absolute byte positions in the file/streams.
> - at item default_base_moof
> -Similarly to the omit_tfhd_offset, this flag avoids writing the
> -absolute base_data_offset field in tfhd atoms, but does so by using
> -the new default-base-is-moof flag instead. This flag is new from
> -14496-12:2012. This may make the fragments easier to parse in certain
> -circumstances (avoiding basing track fragment location calculations
> -on the implicit end of the previous track fragment).
> - at item negative_cts_offsets
> -Enables utilization of version 1 of the CTTS box, in which the CTS
> offsets can
> -be negative. This enables the initial sample to have DTS/CTS of zero, and
> -reduces the need for edit lists for some cases such as video tracks with
> -B-frames. Additionally, eases conformance with the DASH-IF
> interoperability
> -guidelines.
> -
> -This option is implicitly set when writing ismv (Smooth Streaming) files.
> - at end table
> -
> - at item moov_size @var{bytes}
> -Reserves space for the moov atom at the beginning of the file instead of
> placing the
> -moov atom at the end. If the space reserved is insufficient, muxing will
> fail.
> -
> - at item write_tmcd
> -Specify @code{on} to force writing a timecode track, @code{off} to
> disable it
> -and @code{auto} to write a timecode track only for mov and mp4 output
> (default).
> -
> - at item write_btrt @var{bool}
> -Force or disable writing bitrate box inside stsd box of a track.
> -The box contains decoding buffer size (in bytes), maximum bitrate and
> -average bitrate for the track. The box will be skipped if none of these
> values
> -can be computed.
> -Default is @code{-1} or @code{auto}, which will write the box only in MP4
> mode.
> -
> - at item write_prft
> -Write producer time reference box (PRFT) with a specified time source for
> the
> -NTP field in the PRFT box. Set value as @samp{wallclock} to specify
> timesource
> -as wallclock time and @samp{pts} to specify timesource as input packets'
> PTS
> -values.
> -
> -Setting value to @samp{pts} is applicable only for a live encoding use
> case,
> -where PTS values are set as as wallclock time at the source. For example,
> an
> -encoding use case with decklink capture source where @option{video_pts}
> and
> - at option{audio_pts} are set to @samp{abs_wallclock}.
> -
> - at item empty_hdlr_name @var{bool}
> -Enable to skip writing the name inside a @code{hdlr} box.
> -Default is @code{false}.
> -
> - at item movie_timescale @var{scale}
> -Set the timescale written in the movie header box (@code{mvhd}).
> -Range is 1 to INT_MAX. Default is 1000.
> -
> - at item video_track_timescale @var{scale}
> -Set the timescale used for video tracks. Range is 0 to INT_MAX.
> -If set to @code{0}, the timescale is automatically set based on
> -the native stream time base. Default is 0.
> - at end table
> -
> - at subsection Example
> -
> -Smooth Streaming content can be pushed in real time to a publishing
> -point on IIS with this muxer. Example:
> - at example
> -ffmpeg -re @var{<normal input/transcoding options>} -movflags
> isml+frag_keyframe -f ismv
> http://server/publishingpoint.isml/Streams(Encoder1)
> - at end <http://server/publishingpoint.isml/Streams(Encoder1)- at end> example
> -
>  @section mp3
>
>  The MP3 muxer writes a raw MP3 stream with the following optional
> features:
> --
> 2.34.1
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>