mirror of https://github.com/mpv-player/mpv
spelling/punctuation/grammar/wording improvements, no semantic changes
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@22488 b3059339-0415-0410-9bf9-f77b7e298cf2
This commit is contained in:
parent
a708559fe5
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@ -7,73 +7,72 @@ NUT Open Container Format 20061104
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Intro:
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======
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NUT is a Free multimedia container format for storage of audio, video,
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NUT is a free multimedia container format for storage of audio, video,
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subtitles and related user defined streams, it provides exact timestamps for
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synchronization and seeking, is simple, has low overhead and can recover
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in case of errors in the stream
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in case of errors in the stream.
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other common multimedia container formats are AVI, OGG, Matroska, MP4, MOV
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ASF, MPEG-PS, MPEG-TS
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Other common multimedia container formats are AVI, Ogg, Matroska, MP4, MOV
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ASF, MPEG-PS, MPEG-TS.
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Features / goals:
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(supported by the format, not necessarily by a specific implementation)
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Simple
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use the same encoding for nearly all fields
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simple decoding, so slow CPUs (and embedded systems) can handle it
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Simplicity
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Use the same encoding for nearly all fields.
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Simple decoding, so slow CPUs (and embedded systems) can handle it.
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Extendible
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no limit for the possible values of all fields (using universal vlc)
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allow adding of new headers in the future
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allow adding more fields at the end of headers
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Extensibility
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No limit for the possible values of all fields (using universal vlc).
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Allow adding of new headers in the future.
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Allow adding more fields at the end of headers.
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Compact
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~0.2% overhead, for normal bitrates
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index is <100kb per hour
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a usual header for a file is about 100 bytes (audio + video headers together)
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a packet header is about ~1-5 bytes
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Compactness
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~0.2% overhead for normal bitrates.
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The index is <100kb per hour.
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A typical file header is about 100 bytes (audio + video headers together).
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A packet header is about ~1-5 bytes.
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Error resistant
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seeking / playback without an index
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headers & index can be repeated
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damaged files can be played back with minimal data loss and fast
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resync times
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Error resistance
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Seeking / playback is possible without an index.
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Headers & index can be repeated.
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Damaged files can be played back with minimal data loss and fast
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resynchronization times.
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The spec is frozen. All files following spec will be compatible unless the
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spec is unfrozen.
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The specification is frozen. All files following the specification will be
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compatible unless the specification is unfrozen.
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Definitions:
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============
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MUST the specific part must be done to conform to this standard
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SHOULD it is recommended to be done that way, but not strictly required
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MUST The specific part must be done to conform to this standard.
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SHOULD It is recommended to be done that way, but not strictly required.
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keyframe
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A keyframe is a frame from which you can start decoding, a more
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exact definition is below
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The nth frame is a keyframe if and only if frames n, n+1, ... in
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The nth frame is a keyframe if and only if frames n, n+1, ... in
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presentation order (that are all frames with a pts >= frame[n].pts) can
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be decoded successfully without reference to frames prior n in storage
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order (that are all frames with a dts < frame[n].dts)
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if no such frames exist (for example due to use of overlapped transforms
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like the MDCT in an audio codec) then the definition shall be extended
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order (that are all frames with a dts < frame[n].dts).
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If no such frames exist (for example due to using overlapped transforms
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like the MDCT in an audio codec), then the definition shall be extended
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by dropping n out of the set of frames which must be decodable, if this
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is still insufficient then n+1 shall be dropped, and so on until there is
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a keyframe
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every frame which is marked as a keyframe MUST be a keyframe according to
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a keyframe.
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Every frame which is marked as a keyframe MUST be a keyframe according to
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the definition above, a muxer MUST mark every frame it knows is a keyframe
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as such, a muxer SHOULD NOT analyze future frames to determine the
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keyframe status of the current frame but instead just set the frame as
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non keyframe
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non-keyframe.
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(FIXME maybe move somewhere else?)
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pts
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presentation time of the first frame/sample that is completed by decoding
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Presentation time of the first frame/sample that is completed by decoding
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the coded frame.
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dts
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of a frame is the time when it is input into a synchronous 1-in-1-out
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decoder
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The time when a frame is input into a synchronous 1-in-1-out decoder.
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Syntax:
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@ -96,7 +95,7 @@ name (text description)
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[Optional notes]
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The bitstream syntax elements have a tagname and a functional definition, they
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are presented in a bottom up approach, again optional notes may follow and
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are presented in a bottom-up approach, again optional notes may follow and
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are reproduced in the tag description:
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name: (optional note)
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@ -166,10 +165,10 @@ file:
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frame
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}
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the structure of an undamaged file should look like the following, but
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The structure of an undamaged file should look like the following, but
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demuxers should be flexible and be able to deal with damaged headers so the
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above is a better loop in practice (not to mention it is simpler)
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note, demuxers MUST be able to deal with new and unknown headers
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above is a better loop in practice (not to mention it is simpler).
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Note: Demuxers MUST be able to deal with new and unknown headers.
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file:
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file_id_string
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@ -203,10 +202,10 @@ Common elements:
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reserved_bytes:
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for(i=0; i<forward_ptr - length_of_non_reserved; i++)
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reserved u(8)
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[a demuxer MUST ignore any reserved bytes
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a muxer MUST NOT write any reserved bytes, as this would make it
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[A demuxer MUST ignore any reserved bytes.
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A muxer MUST NOT write any reserved bytes, as this would make it
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impossible to add new fields at the end of packets in the future
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in a compatible way]
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in a compatible way.]
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packet_header
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startcode f(64)
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@ -368,8 +367,8 @@ index:
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info_packet:
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stream_id_plus1 v
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chapter_id s (Note due to a typo this was v
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until 2006-11-04)
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chapter_id s (Note: Due to a typo this was v
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until 2006-11-04.)
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chapter_start t
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chapter_len v
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count v
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@ -411,8 +410,7 @@ Tag description:
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file_id_string
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"nut/multimedia container\0"
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the very first thing in every nut file, useful for identifying nut
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files
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The very first thing in every NUT file, useful for identifying NUT files.
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*_startcode (f(64))
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all startcodes start with 'N'
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@ -433,24 +431,24 @@ info_startcode (f(64))
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0xAB68B596BA78ULL + (((uint64_t)('N'<<8) + 'I')<<48)
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version (v)
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NUT version. The current value is 3. All lower values are pre-freeze
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NUT version. The current value is 3. All lower values are pre-freeze.
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stream_count (v)
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number of streams in this file
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time_base_count (v)
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number of different time bases in this file
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this MUST NOT be 0
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This MUST NOT be 0.
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forward_ptr (v)
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size of the packet data (exactly the distance from the first byte
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after the packet_header to the first byte of the next packet)
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every nut packet contains a forward_ptr immediately after its startcode
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with the exception of frame_code based packets, the forward pointer
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can be used to skip over the packet without decoding its contents
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Size of the packet data (exactly the distance from the first byte
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after the packet_header to the first byte of the next packet).
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Every NUT packet contains a forward_ptr immediately after its startcode
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with the exception of frame_code-based packets. The forward pointer
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can be used to skip over the packet without decoding its contents.
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max_distance (v)
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max distance between startcodes. If p1 and p2 are the byte
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maximum distance between startcodes. If p1 and p2 are the byte
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positions of the first byte of two consecutive startcodes, then
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p2-p1 MUST be less than or equal to max_distance unless the entire
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span from p1 to p2 comprises a single packet or a syncpoint
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@ -459,25 +457,25 @@ max_distance (v)
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frame headers, should a chain of frame headers pass max_distance
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without encountering any startcode.
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syncpoints SHOULD be placed immediately before a keyframe if the
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Syncpoints SHOULD be placed immediately before a keyframe if the
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previous frame of the same stream was a non-keyframe, unless such
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non-keyframe - keyframe transitions are very frequent
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non-keyframe - keyframe transitions are very frequent.
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SHOULD be set to <=32768
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if the stored value is >65536 then max_distance MUST be set to 65536
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SHOULD be set to <=32768.
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If the stored value is >65536 then max_distance MUST be set to 65536.
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This is also half the max frame size without a checksum after the
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frameheader.
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This is also half the maximum frame size without a checksum after the
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frame header.
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max_pts_distance (v)
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max absolute difference of pts of new frame from last_pts in the
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timebase of the stream, without a checksum after the frameheader.
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Maximum absolute difference of the pts of the new frame from last_pts in
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the timebase of the stream, without a checksum after the frame header.
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A frame header MUST include a checksum if abs(pts-last_pts) is
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strictly greater than max_pts_distance.
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Note that last_pts is not necessarily the pts of the last frame
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on the same stream, as it is altered by syncpoint timestamps.
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SHOULD NOT be higher than 1/timebase
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SHOULD NOT be higher than 1/timebase.
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stream_id (v)
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Stream identifier
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@ -488,16 +486,16 @@ stream_class (v)
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1 audio
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2 subtitles
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3 userdata
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Note: the remaining values are reserved and MUST NOT be used
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a demuxer MUST ignore streams with reserved classes
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Note: The remaining values are reserved and MUST NOT be used.
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A demuxer MUST ignore streams with reserved classes.
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fourcc (vb)
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identification for the codec
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example: "H264"
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MUST contain 2 or 4 bytes, note, this might be increased in the future
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if needed
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the id values used are the same as in avi, so if a codec uses a specific
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fourcc in avi then the same fourcc MUST be used here
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if needed.
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The ID values used are the same as in AVI, so if a codec uses a specific
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FourCC in AVI then the same FourCC MUST be used here.
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time_base_num (v) / time_base_denom (v) = time_base
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the length of a timer tick in seconds, this MUST be equal to the 1/fps
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@ -515,7 +513,7 @@ time_base_num (v) / time_base_denom (v) = time_base
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time_base_id (v)
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index into the time_base table
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MUST be < time_base_count
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MUST be < time_base_count.
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convert_ts
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To switch from 2 different timebases, the following calculation is
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d1 = from_time_base_denom
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d2 = to_time_base_num
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timestamp = (ln/d1*sn + ln%d1*sn/d1)/d2
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Note: this calculation MUST be done with unsigned 64 bit integers, and
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is equivalent to (ln*sn)/(d1*d2) but this would require a 96bit integer
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Note: This calculation MUST be done with unsigned 64 bit integers, and
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is equivalent to (ln*sn)/(d1*d2) but this would require a 96 bit integer.
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compare_ts
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Compares timestamps from 2 different timebases,
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@ -549,16 +547,16 @@ compare_ts
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msb_pts_shift (v)
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amount of bits in lsb_pts
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MUST be <16
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MUST be <16.
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decode_delay (v)
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size of the reordering buffer used to convert pts to dts
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codecs which don't support b frames normally use 0
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mpeg1/mpeg2 style codecs with b frames use 1
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h264 style b pyramid uses 2
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h264 and future codecs might need values >2
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audio codecs generally use 0 (we aren't aware of any which doesn't
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but its theoretically possible that one exists which needs it >0)
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Size of the reordering buffer used to convert pts to dts.
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Codecs which do not support B-frames normally use 0.
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MPEG-1/MPEG-2-style codecs with B-frames use 1.
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H.264-style B-pyramid uses 2.
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H.264 and future codecs might need values >2.
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Audio codecs generally use 0. (We are not aware of any, but it
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is theoretically possible that a codec might need a value >0.)
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decode_delay MUST NOT be set higher than necessary for a codec.
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stream_flags (v)
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1 FLAG_FIXED_FPS indicates that the fps is fixed
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codec_specific_data (vb)
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private global data for a codec (could be huffman tables or ...)
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if a codec has a global header it SHOULD be placed in here instead of
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at the start of every keyframe
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the exact format is specified in the codec spec
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for H.264 the NAL units MUST be formatted as in a bytestream
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(with 00 00 01 prefixes)
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Private global data for a codec (could be huffman tables or ...).
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If a codec has a global header it SHOULD be placed in here instead of
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at the start of every keyframe.
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The exact format is specified in the codec specification.
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For H.264 the NAL units MUST be formatted as in a bytestream
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(with 00 00 01 prefixes).
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codec_specific_data SHOULD contain exactly the essential global packets
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needed to decode a stream, more specifically it SHOULD NOT contain packets
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which contain only non essential metadata like author, title, ...
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it also MUST NOT contain normal packets which cause the reference decoder
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to generate any specific decoded samples
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the encoder name and version, shall be considered essential as it is very
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usefull to workaround possible encoder bugs
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It also MUST NOT contain normal packets which cause the reference decoder
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to generate any specific decoded samples.
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The encoder name and version shall be considered essential as it is very
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useful to work around possible encoder bugs.
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The global headers MUST consist of the normal
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sequence of header packets required for codec initialization, in the
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order defined in the codec spec. An implementation MAY strip metadata and
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other redundant information not necessary for correct playback from the
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global headers as long as no incorrect values are stored and as long as
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the striped result is not less valid per codec spec as before striping
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the stripped result is not less valid per codec spec as before stripping.
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frame_code (f(8))
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frame_code is an 8-bit field which exists before every frame, it can
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store part of the size of the frame, the stream number, the timestamp
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and some flags amongst other things, what is not directly stored
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in it but is needed is stored in various fields immediately after it
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the values stored in it can be found in the main header
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the value 78 ('N') is forbidden to ensure that the byte is always
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different from the first byte of any startcode
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a muxer SHOULD mark 0x00 and 0xFF as invalid to improve error
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detection
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and some flags amongst other things. What is not directly stored
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in it but is needed is stored in various fields immediately after it.
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The values stored in it can be found in the main header.
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The value 78 ('N') is forbidden to ensure that the byte is always
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different from the first byte of any startcode.
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A muxer SHOULD mark 0x00 and 0xFF as invalid to improve error
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detection.
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flags[frame_code], frame_flags (v)
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Bit Name Description
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0 FLAG_KEY if set, frame is keyframe
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1 FLAG_EOR if set, stream has no relevance on
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0 FLAG_KEY If set, the frame is a keyframe.
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1 FLAG_EOR If set, the stream has no relevance on
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presentation. (EOR)
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3 FLAG_CODED_PTS if set, coded_pts is in the frame header
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4 FLAG_STREAM_ID if set, stream_id is coded in the frame header
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5 FLAG_SIZE_MSB if set, data_size_msb is at frame header,
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otherwise data_size_msb is 0
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6 FLAG_CHECKSUM if set then the frame header contains a checksum
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7 FLAG_RESERVED if set, reserved_count is coded in the frame header
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12 FLAG_CODED if set, coded_flags are stored in the frame header.
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13 FLAG_INVALID if set, frame_code is invalid.
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3 FLAG_CODED_PTS If set, coded_pts is in the frame header.
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4 FLAG_STREAM_ID If set, stream_id is coded in the frame header.
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5 FLAG_SIZE_MSB If set, data_size_msb at the frame header,
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otherwise data_size_msb is 0.
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6 FLAG_CHECKSUM If set, the frame header contains a checksum.
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7 FLAG_RESERVED If set, reserved_count is coded in the frame header.
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12 FLAG_CODED If set, coded_flags are stored in the frame header.
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13 FLAG_INVALID If set, frame_code is invalid.
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EOR frames MUST be zero-length and must be set keyframe.
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All streams SHOULD end with EOR, where the pts of the EOR indicates the
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@ -622,52 +620,52 @@ flags[frame_code], frame_flags (v)
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defined as below).
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last_pts
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the timestamp of the last frame with the same stream_id as the current
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if there is no such frame between the last syncpoint and the current
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frame then the syncpoint timestamp is used, see global_key_pts
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The timestamp of the last frame with the same stream_id as the current.
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If there is no such frame between the last syncpoint and the current
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frame then the syncpoint timestamp is used, see global_key_pts.
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stream_id[frame_code] (v)
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if FLAG_STREAM_ID is not set then this is the stream number for the
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frame following this frame_code
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if FLAG_STREAM_ID is set then this value has no meaning
|
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MUST be <250
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If FLAG_STREAM_ID is not set then this is the stream number for the
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frame following this frame_code.
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If FLAG_STREAM_ID is set then this value has no meaning.
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MUST be <250.
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data_size_mul[frame_code] (v)
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if FLAG_SIZE_MSB is set then data_size_msb which is stored after the
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If FLAG_SIZE_MSB is set then data_size_msb which is stored after the
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frame code is multiplied with it and forms the more significant part
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of the size of the following frame
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if FLAG_SIZE_MSB is not set then this field has no meaning
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MUST be <16384
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of the size of the following frame.
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If FLAG_SIZE_MSB is not set then this field has no meaning.
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MUST be <16384.
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data_size_lsb[frame_code] (v)
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the less significant part of the size of the following frame
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this added together with data_size_mul*data_size_msb is the size of
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the following frame
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MUST be <16384
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The less significant part of the size of the following frame.
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This added together with data_size_mul*data_size_msb is the size of
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the following frame.
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MUST be <16384.
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pts_delta[frame_code] (s)
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MUST be <16384 and >-16384
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||||
if FLAG_CODED_PTS is set in the flags of the current frame then this
|
||||
If FLAG_CODED_PTS is set in the flags of the current frame then this
|
||||
value MUST be ignored, if FLAG_CODED_PTS is not set then pts_delta is the
|
||||
difference between the current pts and last_pts
|
||||
difference between the current pts and last_pts.
|
||||
MUST be <16384 and >-16384.
|
||||
|
||||
reserved_count[frame_code] (v)
|
||||
MUST be <256
|
||||
MUST be <256.
|
||||
|
||||
data_size
|
||||
the size of the following frame
|
||||
data_size= data_size_lsb + data_size_msb*data_size_mul;
|
||||
The size of the following frame.
|
||||
data_size = data_size_lsb + data_size_msb * data_size_mul ;
|
||||
|
||||
coded_pts (v)
|
||||
if coded_pts < (1<<msb_pts_shift) then it is an lsb
|
||||
pts, otherwise it is a full pts + (1<<msb_pts_shift)
|
||||
If coded_pts < ( 1 << msb_pts_shift ) then it is an lsb
|
||||
pts, otherwise it is a full pts + ( 1 << msb_pts_shift ).
|
||||
lsb pts is converted to a full pts by:
|
||||
mask = (1<<msb_pts_shift)-1;
|
||||
delta = last_pts - mask/2
|
||||
pts = ((pts_lsb-delta)&mask) + delta
|
||||
mask = ( 1 << msb_pts_shift ) - 1;
|
||||
delta = last_pts - mask / 2
|
||||
pts = ( (pts_lsb - delta) & mask ) + delta
|
||||
|
||||
lsb_pts
|
||||
least significant bits of the pts in time_base precision
|
||||
Least significant bits of the pts in time_base precision.
|
||||
Example: IBBP display order
|
||||
keyframe pts=0 -> pts=0
|
||||
frame lsb_pts=3 -> pts=3
|
||||
|
@ -680,33 +678,33 @@ lsb_pts
|
|||
frame lsb_pts=4 -> pts=260
|
||||
frame lsb_pts=2 -> pts=258
|
||||
frame lsb_pts=3 -> pts=259
|
||||
all pts's of keyframes of a single stream MUST be monotone
|
||||
All pts values of keyframes of a single stream MUST be monotone.
|
||||
|
||||
dts
|
||||
decoding timestamp
|
||||
the dts of a frame is the timestamp of the first sample which is
|
||||
output by a decoder when it is fed with the frame, note that the
|
||||
The dts of a frame is the timestamp of the first sample which is
|
||||
output by a decoder when it is fed with the frame. Note that the
|
||||
data output is not necessarily what is coded in the frame, but may
|
||||
be data from previous frames
|
||||
dts is calculated by using a decode_delay+1 sized buffer for each
|
||||
be data from previous frames.
|
||||
dts is calculated by using a decode_delay + 1 sized buffer for each
|
||||
stream, into which the current pts is inserted and the element with
|
||||
the smallest value is removed, this is then the current dts
|
||||
this buffer is initialized with decode_delay -1 elements
|
||||
the smallest value is removed. This is then the current dts.
|
||||
This buffer is initialized with decode_delay - 1 elements.
|
||||
|
||||
Pts of all frames in all streams MUST be bigger or equal to dts of all
|
||||
pts of all frames in all streams MUST be bigger or equal to dts of all
|
||||
previous frames in all streams, compared in common timebase. (EOR
|
||||
frames are NOT exempt from this rule)
|
||||
Dts of all frames MUST be bigger or equal to dts of all previous frames
|
||||
in the same stream
|
||||
frames are NOT exempt from this rule.)
|
||||
dts of all frames MUST be bigger or equal to dts of all previous frames
|
||||
in the same stream.
|
||||
|
||||
width (v) / height (v)
|
||||
width and height of the video in pixels
|
||||
MUST be set to the coded width/height, MUST NOT be 0
|
||||
Width and height of the video in pixels.
|
||||
MUST be set to the coded width/height, MUST NOT be 0.
|
||||
|
||||
sample_width (v) /sample_height (v) (aspect ratio)
|
||||
sample_width is the horizontal distance between samples
|
||||
sample_width and sample_height MUST be relatively prime if not zero
|
||||
both MUST be 0 if unknown otherwise both MUST be non zero
|
||||
sample_width is the horizontal distance between samples.
|
||||
sample_width and sample_height MUST be relatively prime if not zero.
|
||||
Both MUST be 0 if unknown otherwise both MUST be nonzero.
|
||||
|
||||
colorspace_type (v)
|
||||
0 unknown
|
||||
|
@ -716,21 +714,21 @@ colorspace_type (v)
|
|||
18 ITU Rec 709 Y range: 0..255 Cb/Cr range: 0..255
|
||||
|
||||
samplerate_num (v) / samplerate_denom (v) = samplerate
|
||||
the number of samples per second, MUST NOT be 0
|
||||
The number of samples per second, MUST NOT be 0.
|
||||
|
||||
crc32 checksum
|
||||
Generator polynomial is 0x104C11DB7. Starting value is zero.
|
||||
|
||||
checksum (u(32))
|
||||
crc32 checksum
|
||||
checksum is calculated for the area pointed to by forward_ptr not
|
||||
including the checksum itself (from first byte after the
|
||||
The checksum is calculated for the area pointed to by forward_ptr
|
||||
not including the checksum itself (from first byte after the
|
||||
packet_header until last byte before the checksum).
|
||||
for frame headers the checksum contains the framecode byte and all
|
||||
following bytes up to the checksum itself
|
||||
For frame headers the checksum contains the framecode byte and all
|
||||
following bytes up to the checksum itself.
|
||||
|
||||
header_checksum (u(32))
|
||||
checksum over the startcode and forward pointer
|
||||
Checksum over the startcode and forward pointer.
|
||||
|
||||
Syncpoint tags:
|
||||
---------------
|
||||
|
@ -738,7 +736,7 @@ Syncpoint tags:
|
|||
back_ptr_div16 (v)
|
||||
back_ptr = back_ptr_div16 * 16 + 15
|
||||
back_ptr must point to a position up to 15 bytes before a syncpoint
|
||||
startcode. Relative to position of current syncpoint. The syncpoint
|
||||
startcode, relative to position of current syncpoint. The syncpoint
|
||||
pointed to MUST be the closest syncpoint such that at least one keyframe
|
||||
with a pts lower or equal to the current syncpoint's global_key_pts for
|
||||
all streams lies between it and the current syncpoint.
|
||||
|
@ -756,23 +754,23 @@ Index tags:
|
|||
-----------
|
||||
|
||||
max_pts (t)
|
||||
The highest pts in the entire file
|
||||
the highest pts in the entire file
|
||||
|
||||
syncpoints (v)
|
||||
number of indexed syncpoints
|
||||
|
||||
syncpoint_pos_div16 (v)
|
||||
offset from beginning of file to up to 15 bytes before the syncpoint
|
||||
referred to in this index entry. Relative to position of last
|
||||
The offset from the beginning of the file to up to 15 bytes before the
|
||||
syncpoint referred to in this index entry. Relative to position of last
|
||||
syncpoint.
|
||||
|
||||
has_keyframe
|
||||
indicates whether this stream has a keyframe between this syncpoint and
|
||||
Indicates whether this stream has a keyframe between this syncpoint and
|
||||
the last syncpoint.
|
||||
|
||||
keyframe_pts
|
||||
The pts of the first keyframe for this stream in the region between the
|
||||
2 syncpoints, in the stream's timebase. (EOR frames are also keyframes)
|
||||
2 syncpoints, in the stream's timebase. (EOR frames are also keyframes.)
|
||||
|
||||
eor_pts
|
||||
Coded only if EOR is set at the position of the syncpoint. The pts of
|
||||
|
@ -790,22 +788,23 @@ Info tags:
|
|||
----------
|
||||
|
||||
stream_id_plus1 (v)
|
||||
Stream this info packet applies to. If zero, packet applies to whole
|
||||
file.
|
||||
Stream this info packet applies to. If zero, packet applies to the
|
||||
whole file.
|
||||
|
||||
chapter_id (s)
|
||||
Id of chapter this packet applies to. If zero, packet applies to whole
|
||||
file. Positive chapter_id's are real chapters and MUST NOT overlap.
|
||||
Negative chapter_id indicate a sub region of file and not a real
|
||||
The ID of the chapter this packet applies to. If zero, the packet applies
|
||||
to the whole file. Positive chapter_id values represent real chapters and
|
||||
MUST NOT overlap.
|
||||
A negative chapter_id indicates a sub region of the file and not a real
|
||||
chapter. chapter_id MUST be unique to the region it represents.
|
||||
chapter_id n MUST not be used unless there are at least n chapters in the
|
||||
file
|
||||
chapter_id n MUST NOT be used unless there are at least n chapters in the
|
||||
file.
|
||||
|
||||
chapter_start (t)
|
||||
timestamp of start of chapter
|
||||
|
||||
chapter_len (v)
|
||||
Length of chapter in same timebase of chapter_start.
|
||||
Length of chapter in the same timebase as chapter_start.
|
||||
|
||||
count (v)
|
||||
number of name/value pairs in this info packet
|
||||
|
@ -815,94 +814,95 @@ type
|
|||
"v" -> unsigned integer
|
||||
"s" -> signed integer
|
||||
"r" -> rational
|
||||
Note: nonstandard fields should be prefixed by "X-"
|
||||
Note: MUST be less than 6 byte long (might be increased to 64 later)
|
||||
Note: Nonstandard fields should be prefixed by "X-".
|
||||
Note: MUST be less than 6 byte long (might be increased to 64 later).
|
||||
|
||||
info packet types
|
||||
the name of the info entry, valid names are
|
||||
The name of the info entry. Valid names are
|
||||
"Author"
|
||||
"Description"
|
||||
"Copyright"
|
||||
"Encoder"
|
||||
the name & version of the software used for encoding
|
||||
The name & version of the software used for encoding.
|
||||
"Title"
|
||||
"Cover" (allowed types are "PNG" and "JPEG")
|
||||
image of the (CD, DVD, VHS, ..) cover (preferably PNG or JPEG)
|
||||
"Source"
|
||||
"DVD", "VCD", "CD", "MD", "FM radio", "VHS", "TV", "LD"
|
||||
Optional: appended PAL, NTSC, SECAM, ... in parentheses
|
||||
Optional: Appended PAL, NTSC, SECAM, ... in parentheses.
|
||||
"SourceContainer"
|
||||
"nut", "mkv", "mov", "avi", "ogg", "rm", "mpeg-ps", "mpeg-ts", "raw"
|
||||
"SourceCodecTag"
|
||||
the source codec id like a fourcc which was used to store a specific
|
||||
stream in its SourceContainer
|
||||
The source codec ID like a FourCC which was used to store a specific
|
||||
stream in its SourceContainer.
|
||||
"CaptureDevice"
|
||||
"BT878", "BT848", "webcam", ... (more exact names are fine too)
|
||||
"BT878", "BT848", "webcam", ... (or more precise names)
|
||||
"CreationTime"
|
||||
"2003-01-20 20:13:15Z", ...
|
||||
(ISO 8601 format, see http://www.cl.cam.ac.uk/~mgk25/iso-time.html)
|
||||
Note: do not forget the timezone
|
||||
Note: Do not forget the timezone.
|
||||
"Keywords"
|
||||
"Language"
|
||||
An ISO 639-2 (three-letter) language code, optionally followed by an
|
||||
ISO 3166-1 country code that is separated from the language
|
||||
code by a hyphen. All codes defined in ISO 639-2 are allowed,
|
||||
including "und" (Undetermined), "mul" (Multiple languages)
|
||||
see http://www.loc.gov/standards/iso639-2/
|
||||
including "und" (Undetermined), "mul" (Multiple languages).
|
||||
See http://www.loc.gov/standards/iso639-2/
|
||||
and http://www.din.de/gremien/nas/nabd/iso3166ma/codlstp1/en_listp1.html
|
||||
the language code
|
||||
a demuxer MUST ignore unknown language and country codes instead of
|
||||
treating them as an error
|
||||
A demuxer MUST ignore unknown language and country codes instead of
|
||||
treating them as an error.
|
||||
"Disposition"
|
||||
"original", "dub" (translated), "comment", "lyrics", "karaoke"
|
||||
Note: if someone needs some others, please tell us about them, so we
|
||||
can add them to the official standard (if they are sane)
|
||||
Note: nonstandard fields should be prefixed by "X-"
|
||||
Note: names of fields SHOULD be in English if a word with the same
|
||||
meaning exists in English
|
||||
Note: MUST be less than 64 bytes long
|
||||
Note: If someone needs some others, please tell us about them, so we
|
||||
can add them to the official standard (if they are sane).
|
||||
Note: Nonstandard fields should be prefixed by "X-".
|
||||
Note: Names of fields SHOULD be in English if a word with the same
|
||||
meaning exists in English.
|
||||
Note: MUST be less than 64 bytes long.
|
||||
|
||||
value
|
||||
value of this name/type pair
|
||||
|
||||
stuffing
|
||||
0x80 can be placed in front of any type v entry for stuffing purposes
|
||||
except the forward_ptr and all fields in the frame header where a
|
||||
maximum of 8 stuffing bytes per field are allowed
|
||||
0x80 can be placed in front of any type v entry for stuffing purposes.
|
||||
Exceptions are the forward_ptr and all fields in the frame header where
|
||||
a maximum of 8 stuffing bytes per field are allowed.
|
||||
|
||||
|
||||
Structure:
|
||||
----------
|
||||
|
||||
the headers MUST be in exactly the following order (to simplify demuxer design)
|
||||
The headers MUST be in exactly the following order (to simplify demuxer design).
|
||||
|
||||
main header
|
||||
stream_header (id=0)
|
||||
stream_header (id=1)
|
||||
...
|
||||
stream_header (id=n)
|
||||
|
||||
headers may be repeated, but if they are, then they MUST all be repeated
|
||||
together and repeated headers MUST be identical
|
||||
Headers may be repeated, but if they are, then they MUST all be repeated
|
||||
together and repeated headers MUST be identical.
|
||||
|
||||
Each set of repeated headers not at the beginning or end of the file SHOULD
|
||||
be stored at the earliest possible position after 2^x where x is
|
||||
an integer and the file end, so the headers may be repeated at 4102 if that is
|
||||
the closest position after 2^12=4096 at which the headers can be placed
|
||||
be stored at the earliest possible position after 2^x where x is an integer
|
||||
and the end of the file. So the headers may be repeated at 4102 if that is
|
||||
the closest position after 2^12=4096 at which the headers can be placed.
|
||||
|
||||
Note: this allows an implementation reading the file to locate backup
|
||||
headers in O(log filesize) time as opposed to O(filesize)
|
||||
Note: This allows an implementation reading the file to locate backup
|
||||
headers in O(log filesize) time as opposed to O(filesize).
|
||||
|
||||
headers MUST be placed at least at the start of the file and immediately before
|
||||
the index or at the file end if there is no index
|
||||
headers MUST be repeated at least twice (so they exist three times in a file)
|
||||
Headers MUST be placed at least at the start of the file and immediately before
|
||||
the index or at the end of the file if there is no index.
|
||||
Headers MUST be repeated at least twice (so they exist three times in a file).
|
||||
|
||||
there MUST be a sync point immediately before the first frame after any headers
|
||||
There MUST be a syncpoint immediately before the first frame after any headers.
|
||||
|
||||
|
||||
Index:
|
||||
------
|
||||
|
||||
Note: with realtime streaming, there is no end, so no index there either
|
||||
Note: With realtime streaming, there is no end, so no index there either.
|
||||
Index MAY only be repeated after main headers.
|
||||
If an index is written anywhere in the file, it MUST be written at end of
|
||||
file as well.
|
||||
|
@ -911,55 +911,56 @@ file as well.
|
|||
Info:
|
||||
-----
|
||||
|
||||
If a info packet is stored anywhere then a muxer MUST also store an identical
|
||||
info packet after every main-stream-header set
|
||||
If an info packet is stored anywhere then a muxer MUST also store an identical
|
||||
info packet after every main-stream-header set.
|
||||
|
||||
If a demuxer has seen several info packets with the same chapter_id and
|
||||
stream_id then it MUST ignore all but the one with the highest position in
|
||||
the file
|
||||
the file.
|
||||
|
||||
demuxers SHOULD NOT search the whole file for info packets
|
||||
Demuxers SHOULD NOT search the whole file for info packets.
|
||||
|
||||
demuxer (non-normative):
|
||||
------------------------
|
||||
|
||||
in the absence of a valid header at the beginning, players SHOULD search for
|
||||
In the absence of a valid header at the beginning, players SHOULD search for
|
||||
backup headers starting at offset 2^x; for each x players SHOULD end their
|
||||
search at a particular offset when any startcode is found (including syncpoint)
|
||||
search at a particular offset when any startcode (including a syncpoint) is
|
||||
found.
|
||||
|
||||
|
||||
Seeking without an index (non-normative):
|
||||
-----------------------------------------
|
||||
A. backward seeking
|
||||
1. perform a binary search on the syncpoint timestamps finding the one
|
||||
which is largest and <= the target timestamp
|
||||
1. Perform a binary search on the syncpoint timestamps finding the one
|
||||
which is largest and <= the target timestamp.
|
||||
B. forward seeking
|
||||
1a. perform a binary search on the syncpoint timestamps finding the one
|
||||
which is smallest and >= the target timestamp
|
||||
1b. perform a binary search on the syncpoint back pointers finding the
|
||||
1a. Perform a binary search on the syncpoint timestamps finding the one
|
||||
which is smallest and >= the target timestamp.
|
||||
1b. Perform a binary search on the syncpoint back pointers finding the
|
||||
smallest one which has a back ptr >= the position of what was found in 1.
|
||||
2. follow the back pointer to the corresponding syncpoint
|
||||
2. Follow the back pointer to the corresponding syncpoint.
|
||||
|
||||
Seeking with an index (non-normative):
|
||||
--------------------------------------
|
||||
The demuxer only has to find the appropriate keyframe in the index and
|
||||
start demuxing from the previous syncpoint
|
||||
start demuxing from the previous syncpoint.
|
||||
|
||||
Note, more complicated seeking methods exist which are capable of quickly
|
||||
seeking to the optimal point in the presence of an index even if only a
|
||||
subset of all streams is active
|
||||
subset of all streams is active.
|
||||
|
||||
A muxer SHOULD place syncpoints so that that simple low complexity seeking
|
||||
works with fine granularity, that is syncpoints should be placed prior
|
||||
to keyframes instead of non keyframes and with high enough frequency
|
||||
works with fine granularity. That is, syncpoints should be placed prior
|
||||
to keyframes instead of non-keyframes and with high enough frequency
|
||||
(once per second unless there are no keyframes between this and the previous
|
||||
syncpoint)
|
||||
syncpoint).
|
||||
|
||||
encoders SHOULD place keyframes so that the number of points where all
|
||||
streams have a keyframe at the same time is maximized, this ensures that
|
||||
Encoders SHOULD place keyframes so that the number of points where all
|
||||
streams have a keyframe at the same time is maximized. This ensures that
|
||||
seeking (complicated or not) does not need to demux and decode significant
|
||||
amounts of data to reach a point where a presentable frame for each stream
|
||||
is available after seeking
|
||||
is available after seeking.
|
||||
|
||||
|
||||
Semantic requirements:
|
||||
|
@ -971,9 +972,9 @@ It often highly improves usability and is therefore strongly encouraged.
|
|||
|
||||
A demuxer MUST NOT demux a stream which contains more than one stream, or which
|
||||
is wrapped in a structure to facilitate more than one stream or otherwise
|
||||
duplicate the role of a container. any such file is to be considered invalid.
|
||||
for example vorbis in ogg in nut is invalid, as is
|
||||
mpegvideo+mpegaudio in mpeg-ps/ts in nut or dvvideo + dvaudio in dv in nut
|
||||
duplicate the role of a container. Any such file is to be considered invalid.
|
||||
For example Vorbis in Ogg in NUT is invalid, as is
|
||||
mpegvideo + mpegaudio in MPEG-PS/TS in NUT or dvvideo + dvaudio in DV in NUT.
|
||||
|
||||
|
||||
|
||||
|
@ -1029,7 +1030,7 @@ static inline int put_v(BufferContext *bc, uint64_t val){
|
|||
|
||||
if(space_left(bc) < 9) return -1;
|
||||
|
||||
val &= 0x7FFFFFFFFFFFFFFFULL; // FIXME can only encode up to 63 bits currently
|
||||
val &= 0x7FFFFFFFFFFFFFFFULL; // FIXME: Can only encode up to 63 bits ATM.
|
||||
for(i=7; ; i+=7){
|
||||
if(val>>i == 0) break;
|
||||
}
|
||||
|
|
Loading…
Reference in New Issue