Subtitles
+ +Because Matroska is a general container format, we try to avoid specifying the formats +to store in it. This type of work is really outside of the scope of a container-only format. +However, because the use of subtitles in A/V containers has been so limited (with the exception of DVD) +we are taking the time to specify how to store some of the more common subtitle formats in Matroska. +This is being done to help facilitate their growth. Otherwise, incompatibilities could prevent +the standardization and use of subtitle storage.
+ +This page is not meant to be a complete listing of all subtitle formats that will be used in Matroska, +it is only meant to be a guide for the more common, current formats. It is possible that +we will add future formats to this page as they are created, but it is not likely as any +other new subtitle format designer would likely have their own specifications. +Any specification listed here SHOULD be strictly adhered to or it SHOULD NOT +use the corresponding Codec ID.
+ +Here is a list of pointers for storing subtitles in Matroska:
+ +-
+
- Any Matroska file containing only subtitles SHOULD use the extension “.mks”. +
- As a general rule of thumb for all codecs, information that is global to an entire stream +SHOULD be stored in the CodecPrivate element. +
- Start and stop timestamps that are used in a timestamps native storage format SHOULD +be removed when being placed in Matroska as they could interfere if the file is edited +afterwards. Instead, the Blocks timestamp and Duration SHOULD be used to say when the timestamp is displayed. +
- Because a “subtitle” stream is actually just an overlay stream, anything with a transparency +layer could be use, including video. +
Images Subtitles
+ +The first image format that is a goal to import into Matroska is the VobSub subtitle format. +This subtitle type is generated by exporting the subtitles from a DVD [@?DVD-Video].
+ +The requirement for muxing VobSub into Matroska is v7 subtitles (see first line of the .IDX file). +If the version is smaller, you must remux them using the SubResync utility from +VobSub 2.23 (or MPC) into v7 format. Generally any newly created subs will be in v7 format.
+ +The .IFO file will not be used at all.
+ +If there is more than one subtitle stream in the VobSub set, each stream will need to be +separated into separate tracks for storage in Matroska. E.g. the VobSub file contains +streams for both English and German subtitles. Then the resulting Matroska file SHOULD +contain two tracks. That way the language information can be dropped and mapped +to Matroska’s language tags.
+ +The .IDX file is reformatted (see below) and placed in the CodecPrivate.
+ +Each .BMP will be stored in its own Block. The Timestamp with be stored in the Blocks Timestamp +and the duration will be stored in the Default Duration.
+ +Here is an example .IDX file:
+ + # VobSub index file, v7 (do not modify this line!)
+ #
+ # To repair desynchronization, you can insert gaps this way:
+ # (it usually happens after vob id changes)
+ #
+ # delay: [sign]hh:mm:ss:ms
+ #
+ # Where:
+ # [sign]: +, - (optional)
+ # hh: hours (0 <= hh)
+ # mm/ss: minutes/seconds (0 <= mm/ss <= 59)
+ # ms: milliseconds (0 <= ms <= 999)
+ #
+ # Note: You can't position a sub before the previous with a negative
+ # value.
+ #
+ # You can also modify timestamps or delete a few subs you don't
+ # like. Just make sure they stay in increasing order.
+
+ # Settings
+
+ # Original frame size
+ size: 720x480
+
+ # Origin, relative to the upper-left corner, can be overloaded by
+ # alignment
+ org: 0, 0
+
+ # Image scaling (hor,ver), origin is at the upper-left corner or at
+ # the alignment coord (x, y)
+ scale: 100%, 100%
+
+ # Alpha blending
+ alpha: 100%
+
+ # Smoothing for very blocky images (use OLD for no filtering)
+ smooth: OFF
+
+ # In millisecs
+ fadein/out: 50, 50
+
+ # Force subtitle placement relative to (org.x, org.y)
+ align: OFF at LEFT TOP
+
+ # For correcting non-progressive desync. (in millisecs or
+ # hh:mm:ss:ms)
+ # Note: Not effective in DirectVobSub, use "delay: ... " instead.
+ time offset: 0
+
+ # ON: displays only forced subtitles, OFF: shows everything
+ forced subs: OFF
+
+ # The original palette of the DVD
+ palette: 000000, 7e7e7e, fbff8b, cb86f1, 7f74b8, e23f06, 0a48ea, \
+ b3d65a, 6b92f1, 87f087, c02081, f8d0f4, e3c411, 382201, e8840b, \
+ fdfdfd
+
+ # Custom colors (transp idxs and the four colors)
+ custom colors: OFF, tridx: 0000, colors: 000000, 000000, 000000, \
+ 000000
+
+ # Language index in use
+ langidx: 0
+
+ # English
+ id: en, index: 0
+ # Uncomment next line to activate alternative name in DirectVobSub /
+ # Windows Media Player 6.x
+ # alt: English
+ # Vob/Cell ID: 1, 1 (PTS: 0)
+ timestamp: 00:00:01:101, filepos: 000000000
+ timestamp: 00:00:08:708, filepos: 000001000
+First, lines beginning with “#” are removed. These are comments to make text file editing easier, +and as this is not a text file, they aren’t needed.
+ +Next remove the “langidx” and “id” lines. These are used to differentiate the subtitle +streams and define the language. As the streams will be stored separately anyway, +there is no need to differentiate them here. Also, the language setting will be stored +in the Matroska tags, so there is no need to store it here.
+ +Finally, the “timestamp” will be used to set the Block’s timestamp. Once it is set there, +there is no need for it to be stored here. Also, as it may interfere if the file is edited, +it SHOULD NOT be stored here.
+ +Once all of these items are removed, the data to store in the CodecPrivate SHOULD look like this:
+ + size: 720x480
+ org: 0, 0
+ scale: 100%, 100%
+ alpha: 100%
+ smooth: OFF
+ fadein/out: 50, 50
+ align: OFF at LEFT TOP
+ time offset: 0
+ forced subs: OFF
+ palette: 000000, 7e7e7e, fbff8b, cb86f1, 7f74b8, e23f06, 0a48ea, \
+ b3d65a, 6b92f1, 87f087, c02081, f8d0f4, e3c411, 382201, e8840b, \
+ fdfdfd
+ custom colors: OFF, tridx: 0000, colors: 000000, 000000, 000000, \
+ 000000
+There SHOULD also be two Blocks containing one image each with the timestamps “00:00:01:101” and “00:00:08:708”.
+ +SRT Subtitles
+ +SRT is perhaps the most basic of all subtitle formats.
+ +It consists of four parts, all in text:
+ +1. A number indicating which subtitle it is in the sequence. +2. The time that the subtitle appears on the screen, and then disappears. +3. The subtitle itself. +4. A blank line indicating the start of a new subtitle.
+ +When placing SRT in Matroska, part 3 is converted to UTF-8 (S_TEXT/UTF8) and placed +in the data portion of the Block. Part 2 is used to set the timestamp of the Block, +and BlockDuration element. Nothing else is used.
+ +Here is an example SRT file:
+ +1
+00:02:17,440 --> 00:02:20,375
+Senator, we're making
+our final approach into Coruscant.
+
+2
+00:02:20,476 --> 00:02:22,501
+Very good, Lieutenant.
+In this example, the text “Senator, we’re making our final approach into Coruscant.” +would be converted into UTF-8 and placed in the Block. The timestamp of the block would +be set to “00:02:17,440”. And the BlockDuration element would be set to “00:00:02,935”.
+ +The same is repeated for the next subtitle.
+ +Because there are no general settings for SRT, the CodecPrivate is left blank.
+ +SSA/ASS Subtitles
+ +SSA stands for Sub Station Alpha. It’s the file format used by the popular subtitle editor, +SubStation Alpha. +This format is widely used by fansubbers.
+ +It allows you to do some advanced display features, like positioning, karaoke, style managements…
+ +For detailed information on SSA/ASS, see the SSA specs. +It includes an SSA specs description and the advanced features added by ASS format (standing for Advanced SSA). +Because SSA and ASS are so similar, they are treated the same here.
+ +Like SRT, this format is text based with a particular syntax.
+ +A file consists of 4 or 5 parts, declared ala INI file (but it’s not an INI !)
+ +The first, “[Script Info]” contains some information about the subtitle file, +such as it’s title, who created it, type of script and a very important one: “PlayResY”. +Be careful of this value, everything in your script (font size, positioning) is scaled by it. +Sub Station Alpha uses your desktops Y resolution to write this value, so if a friend +with a large monitor and a high screen resolution gives you an edited script, +you can mess everything up by saving the script in SSA with your low-cost monitor.
+ +The second, “[V4 Styles]”, is a list of style definitions. A style describe how will look +a text on the screen. It defines font, font size, primary/…/outile colour, position, alignment, etc.
+ +For example this:
+ +Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, \
+TertiaryColour, BackColour, Bold, Italic, BorderStyle, Outline, \
+Shadow, Alignment, MarginL, MarginR, MarginV, AlphaLevel, Encoding
+Style: Wolf main,Wolf_Rain,56,15724527,15724527,15724527,4144959,0,\
+0,1,1,2,2,5,5,30,0,0
+The third, “[Events]”, is the list of text you want to display at the right timing. +You can specify some attribute here. Like the style to use for this event +(MUSTbe defined in the list), the position of the text (Left, Right, Vertical Margin), +an effect. Name is mostly used by translator to know who said this sentence. +Timing is in h:mm:ss.cc (centisec).
+ +Format: Marked, Start, End, Style, Name, MarginL, MarginR, MarginV, \
+Effect, Text
+Dialogue: Marked=0,0:02:40.65,0:02:41.79,Wolf main,Cher,0000,0000,\
+0000,,Et les enregistrements de ses ondes delta ?
+Dialogue: Marked=0,0:02:42.42,0:02:44.15,Wolf main,autre,0000,0000,\
+0000,,Toujours rien.
+“[Pictures]” or “[Fonts]” part can be found in some SSA file, they contains UUE-encoded +pictures/font but those features are only used by Sub Station Alpha – i.e. +no filter (Vobsub/Avery Lee Subtiler filter) use them.
+ +Now, how are they stored in Matroska?
+ +-
+
- All text is converted to UTF-8 +
- All the headers are stored in CodecPrivate + (Script Info and the Styles list) +
- Start & End field are used to set TimeStamp + and the BlockDuration element. the data stored is: +
- Events are stored in the Block + in this order: ReadOrder, Layer, Style, Name, MarginL, MarginR, MarginV, Effect, + Text (Layer comes from ASS specs … it’s empty for SSA.) “ReadOrder field is needed + for the decoder to be able to reorder the streamed samples as they were placed originally in the file.” +
Here is an example of an SSA file.
+ +[Script Info]
+; This is a Sub Station Alpha v4 script.
+; For Sub Station Alpha info and downloads,
+; go to \
+; [http://www.eswat.demon.co.uk/](http://www.eswat.demon.co.uk/)
+; or email \
+; [kotus@eswat.demon.co.uk](mailto:kotus@eswat.demon.co.uk)
+Title: Wolf's rain 2
+Original Script: Anime-spirit Ishin-francais
+Original Translation: Coolman
+Original Editing: Spikewolfwood
+Original Timing: Lord_alucard
+Original Script Checking: Spikewolfwood
+ScriptType: v4.00
+Collisions: Normal
+PlayResY: 1024
+PlayDepth: 0
+Wav: 0, 128697,D:\Alex\Anime\- Fansub -\- TAFF -\WR_-_02_Wav.wav
+Wav: 0, 120692,H:\team truc\WR_-_02.wav
+Wav: 0, 116504,E:\sub\wolf's_rain\WOLF'S RAIN 02.wav
+LastWav: 3
+Timer: 100,0000
+
+[V4 Styles]
+Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, \
+TertiaryColour, BackColour, Bold, Italic, BorderStyle, Outline, \
+Shadow, Alignment, MarginL, MarginR, MarginV, AlphaLevel, Encoding
+Style: Default,Arial,20,65535,65535,65535,-2147483640,-1,0,1,3,0,2,\
+30,30,30,0,0
+Style: Titre_episode,Akbar,140,15724527,65535,65535,986895,-1,0,1,1,\
+0,3,30,30,30,0,0
+Style: Wolf main,Wolf_Rain,56,15724527,15724527,15724527,4144959,0,\
+0,1,1,2,2,5,5,30,0,0
+
+[Events]
+Format: Marked, Start, End, Style, Name, MarginL, MarginR, MarginV, \
+Effect, Text
+Dialogue: Marked=0,0:02:40.65,0:02:41.79,Wolf main,Cher,0000,0000,\
+0000,,Et les enregistrements de ses ondes delta ?
+Dialogue: Marked=0,0:02:42.42,0:02:44.15,Wolf main,autre,0000,0000,\
+0000,,Toujours rien.
+Here is what would be placed into the CodecPrivate element.
+ +[Script Info]
+; This is a Sub Station Alpha v4 script.
+; For Sub Station Alpha info and downloads,
+; go to \
+; [http://www.eswat.demon.co.uk/](http://www.eswat.demon.co.uk/)
+; or email \
+; [kotus@eswat.demon.co.uk](mailto:kotus@eswat.demon.co.uk)
+Title: Wolf's rain 2
+Original Script: Anime-spirit Ishin-francais
+Original Translation: Coolman
+Original Editing: Spikewolfwood
+Original Timing: Lord_alucard
+Original Script Checking: Spikewolfwood
+ScriptType: v4.00
+Collisions: Normal
+PlayResY: 1024
+PlayDepth: 0
+Wav: 0, 128697,D:\Alex\Anime\- Fansub -\- TAFF -\WR_-_02_Wav.wav
+Wav: 0, 120692,H:\team truc\WR_-_02.wav
+Wav: 0, 116504,E:\sub\wolf's_rain\WOLF'S RAIN 02.wav
+LastWav: 3
+Timer: 100,0000
+
+[V4 Styles]
+Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, \
+TertiaryColour, BackColour, Bold, Italic, BorderStyle, Outline, \
+Shadow, Alignment, MarginL, MarginR, MarginV, AlphaLevel, Encoding
+Style: Default,Arial,20,65535,65535,65535,-2147483640,-1,0,1,3,0,2,\
+30,30,30,0,0
+Style: Titre_episode,Akbar,140,15724527,65535,65535,986895,-1,0,1,1,\
+0,3,30,30,30,0,0
+Style: Wolf main,Wolf_Rain,56,15724527,15724527,15724527,4144959,0,\
+0,1,1,2,2,5,5,30,0,0
+And here are the two blocks that would be generated.
+ +Block’s timestamp: 00:02:40.650 +BlockDuration: 00:00:01.140
+ +1,,Wolf main,Cher,0000,0000,0000,,Et les enregistrements de ses \
+ondes delta ?
+Block’s timestamp: 00:02:42.420 +BlockDuration: 00:00:01.730
+ +2,,Wolf main,autre,0000,0000,0000,,Toujours rien.
+WebVTT
+ +The “Web Video Text Tracks Format” (short: WebVTT) is developed by the World Wide Web Consortium (W3C). +Its specifications are freely available.
+ +The guiding principles for the storage of WebVTT in Matroska are:
+ +-
+
- Consistency: store data in a similar way to other subtitle codecs +
- Simplicity: making decoding and remuxing as easy as possible for existing infrastructures +
- Completeness: keeping as much data as possible from the original WebVTT file +
Storage of WebVTT in Matroska
+ +CodecID: codec identification
+ +The CodecID to use is S_TEXT/WEBVTT.
CodecPrivate: storage of global WebVTT blocks
+ +This element contains all global blocks before the first subtitle entry. This starts at the “WEBVTT”
+file identification marker but excludes the optional byte order mark.
Storage of non-global WebVTT blocks
+ +Non-global WebVTT blocks (e.g., “NOTE”) before a WebVTT Cue Text are stored in Matroska’s BlockAddition +element together with the Matroska Block containing the WebVTT Cue Text these blocks precede +(see below for the actual format).
+ +Storage of Cues in Matroska blocks
+ +Each WebVTT Cue Text is stored directly in the Matroska Block.
+ +A muxer MUST change all WebVTT Cue Timestamps present within the Cue Text to be relative +to the Matroska Block’s timestamp.
+ +The Cue’s start timestamp is used as the Matroska Block’s timestamp.
+ +The difference between the Cue’s end timestamp and its start timestamp is used as +the Matroska Block’s duration.
+ +BlockAdditions: storing non-global WebVTT blocks, Cue Settings Lists and Cue identifiers
+ +Each Matroska Block may be accompanied by one BlockAdditions element. Its format is as follows:
+ +-
+
- The first line contains the WebVTT Cue Text’s optional Cue Settings List followed by +one line feed character (U+0x000a). The Cue Settings List may be empty, in which case +the line consists of the line feed character only. +
- The second line contains the WebVTT Cue Text’s optional Cue Identifier followed by +one line feed character (U+0x000a). The line may be empty indicating that there was +no Cue Identifier in the source file, in which case the line consists of the line feed character only. +
- The third and all following lines contain all WebVTT Comment Blocks that precede +the current WebVTT Cue Block. These may be absent. +
If there is no Matroska BlockAddition element stored together with the Matroska Block, +then all three components (Cue Settings List, Cue Identifier, Cue Comments) MUST be assumed to be absent.
+ +Examples of transformation
+ +Here’s an example how a WebVTT is transformed.
+ +Example WebVTT file
+ +Let’s take the following example file:
+ +WEBVTT with text after the signature
+
+STYLE
+::cue {
+ background-image: linear-gradient(to bottom, dimgray, lightgray);
+ color: papayawhip;
+}
+/* Style blocks cannot use blank lines nor "dash dash greater \
+than" */
+
+NOTE comment blocks can be used between style blocks.
+
+STYLE
+::cue(b) {
+ color: peachpuff;
+}
+
+REGION
+id:bill
+width:40%
+lines:3
+regionanchor:0%,100%
+viewportanchor:10%,90%
+scroll:up
+
+NOTE
+Notes always span a whole block and can cover multiple
+lines. Like this one.
+An empty line ends the block.
+
+hello
+00:00:00.000 --> 00:00:10.000
+Example entry 1: Hello <b>world</b>.
+
+NOTE style blocks cannot appear after the first cue.
+
+00:00:25.000 --> 00:00:35.000
+Example entry 2: Another entry.
+This one has multiple lines.
+
+00:01:03.000 --> 00:01:06.500 position:90% align:right size:35%
+Example entry 3: That stuff to the right of the timestamps are cue \
+settings.
+
+00:03:10.000 --> 00:03:20.000
+Example entry 4: Entries can even include timestamps.
+For example:<00:03:15.000>This becomes visible five seconds
+after the first part.
+Example of CodecPrivate
+ +The resulting CodecPrivate element will look like this:
+ +WEBVTT with text after the signature
+
+STYLE
+::cue {
+ background-image: linear-gradient(to bottom, dimgray, lightgray);
+ color: papayawhip;
+}
+/* Style blocks cannot use blank lines nor "dash dash greater \
+than" */
+
+NOTE comment blocks can be used between style blocks.
+
+STYLE
+::cue(b) {
+ color: peachpuff;
+}
+
+REGION
+id:bill
+width:40%
+lines:3
+regionanchor:0%,100%
+viewportanchor:10%,90%
+scroll:up
+
+NOTE
+Notes always span a whole block and can cover multiple
+lines. Like this one.
+An empty line ends the block.
+Storage of Cue 1
+ +Example Cue 1: timestamp 00:00:00.000, duration 00:00:10.000, Block’s content:
+ +Example entry 1: Hello <b>world</b>.
+BlockAddition’s content starts with one empty line as there’s no Cue Settings List:
+ +
+hello
+Storage of Cue 2
+ +Example Cue 2: timestamp 00:00:25.000, duration 00:00:10.000, Block’s content:
+ +Example entry 2: Another entry.
+This one has multiple lines.
+BlockAddition’s content starts with two empty lines as there’s neither a Cue Settings List nor a Cue Identifier:
+ +
+NOTE style blocks cannot appear after the first cue.
+Storage of Cue 3
+ +Example Cue 3: timestamp 00:01:03.000, duration 00:00:03.500, Block’s content:
+ +Example entry 3: That stuff to the right of the timestamps are cue \
+settings.
+BlockAddition’s content ends with an empty line as there’s no Cue Identifier and +there were no WebVTT Comment blocks:
+ +position:90% align:right size:35%
+
+Storage of Cue 4
+ +Example Cue 4: timestamp 00:03:10.000, duration 00:00:10.000, Block’s content:
+ +Example entry 4: Entries can even include timestamps. For +example:<00:00:05.000>This becomes visible five seconds after the +first part.
+ +This Block does not need a BlockAddition as the Cue did not contain an Identifier, +nor a Settings List, and it wasn’t preceded by Comment blocks.
+ +Storage of WebVTT in Matroska vs. WebM
+ +Note: the storage of WebVTT in Matroska is not the same as the design document for storage +of WebVTT in WebM. There are several reasons for this including but not limited to: +the WebM document is old (from February 2012) and was based on an earlier draft of WebVTT +and ignores several parts that were added to WebVTT later; WebM does still not support subtitles at all; +the proposal suggests splitting the information across multiple tracks making +demuxer’s and remuxer’s life very difficult.
+ +HDMV presentation graphics subtitles
+ +The specifications for the HDMV presentation graphics subtitle format (short: HDMV PGS) +can be found in the document “Blu-ray Disc Read-Only Format; Part 3 — Audio Visual Basic Specifications” +in section 9.14 “HDMV graphics streams”.
+ +Storage of HDMV presentation graphics subtitles
+ +The CodecID to use is S_HDMV/PGS. A CodecPrivate element is not used.
Storage of HDMV PGS Segments in Matroska Blocks
+ +Each HDMV PGS Segment (short: Segment) will be stored in a Matroska Block. +A Segment is the data structure described in section 9.14.2.1 “Segment coding structure and parameters” +of the Blu-ray specifications.
+ +Each Segment contains a presentation timestamp. This timestamp will be used as +the timestamp for the Matroska Block.
+ +A Segment is normally shown until a subsequent Segment is encountered. Therefore the Matroska Block +MAY have no Duration. In that case, a player MUST display a Segment within a Matroska Block +until the next Segment is encountered.
+ +A muxer MAY use a Duration, e.g., by calculating the distance between two subsequent Segments. +If a Matroska Block has a Duration, a player MUST display that Segment only for +the duration of the Block’s Duration.
+ +HDMV text subtitles
+ +The specifications for the HDMV text subtitle format (short: HDMV +TextST) can be found +in the document “Blu-ray Disc Read-Only Format; Part 3 — Audio Visual +Basic Specifications” in section 9.15 “HDMV text subtitle streams”.
+ +Storage of HDMV text subtitles
+ +The CodecID to use is S_HDMV/TEXTST.
A CodecPrivate Element is required. It MUST contain the stream’s Dialog Style Segment +as described in section 9.15.4.2 “Dialog Style Segment” of the Blu-ray specifications.
+ +Storage of HDMV TextST Dialog Presentation Segments in Matroska Blocks
+ +Each HDMV Dialog Presentation Segment (short: Segment) will be stored in a Matroska Block. +A Segment is the data structure described in section 9.15.4.3 “Dialog presentation segment” +of the Blu-ray specifications.
+ +Each Segment contains a start and an end presentation timestamp (short: start PTS & end PTS). +The start PTS will be used as the timestamp for the Matroska Block. The Matroska Block MUST +have a Duration, and that Duration is the difference between the end PTS and the start PTS.
+ +A player MUST use the Matroska Block’s timestamp and Duration instead of the Segment’s +start and end PTS for determining when and how long to show the Segment.
+ +Character set
+ +When TextST subtitles are stored inside Matroska, the only allowed character set is UTF-8.
+ +Each HDMV text subtitle stream in a Blu-ray can use one of a handful of character sets. +This information is not stored in the MPEG2 Transport Stream itself but in the accompanying Clip Information file.
+ +Therefore a muxer MUST parse the accompanying Clip Information file. If the information +indicates a character set other than UTF-8, it MUST re-encode all text Dialog Presentation Segments +from the indicated character set to UTF-8 prior to storing them in Matroska.
+ +Digital Video Broadcasting (DVB) subtitles
+ +The specifications for the Digital Video Broadcasting subtitle bitstream format (short: DVB subtitles) +can be found in the document “ETSI EN 300 743 - Digital Video Broadcasting (DVB); Subtitling systems”. +The storage of DVB subtitles in MPEG transport streams is specified in the document +“ETSI EN 300 468 - Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems”.
+ +Storage of DVB subtitles
+ +CodecID
+ +The CodecID to use is S_DVBSUB.
CodecPrivate
+ +The CodecPrivate element is five bytes long and has the following structure:
+ +-
+
- 2 bytes: composition page ID (bit string, left bit first) +
- 2 bytes: ancillary page ID (bit string, left bit first) +
- 1 byte: subtitling type (bit string, left bit first) +
The semantics of these bytes are the same as the ones described in +section 6.2.41 “Subtitling descriptor” of ETSI EN 300 468.
+ +Storage of DVB subtitles in Matroska Blocks
+ +Each Matroska Block consists of one or more DVB Subtitle Segments as described +in segment 7.2 “Syntax and semantics of the subtitling segment” of ETSI EN 300 743.
+ +Each Matroska Block SHOULD have a Duration indicating how long the DVB Subtitle Segments +in that Block SHOULD be displayed.
+ +ARIB (ISDB) subtitles
+ +The specifications for the ARIB B-24 subtitle bitstream format (short: ARIB subtitles) +and its storage in MPEG transport streams can be found in the documents +[@!ARIB.STD-B24], [@!ARIB.STD-B10], and [@!ARIB.TR-B14].
+ +Storage of ARIB subtitles
+ +CodecID
+ +The CodecID to use is S_ARIBSUB.
CodecPrivate
+ +The CodecPrivate element is three bytes long and has the following structure:
+ +-
+
- 1 byte: component tag (bit string, left bit first) +
- 2 bytes: data component ID (bit string, left bit first) +
The semantics of the component tag are the same as those described in + [@!ARIB.STD-B10], part 2, Annex J. +The semantics of the data component ID are the same as those described +in [@!ARIB.TR-B14], fascicle 2, Vol. 3, Section 2, 4.2.8.1.
+ +Storage of ARIB subtitles in Matroska Blocks
+ +Each Matroska Block consists of a single synchronized PES data structure as described in +chapter 5 “Independent PES transmission protocol” of [@!ARIB.STD-B24], volume 3, with a +Synchronized_PES_data_byte block containing one or more ISDB Caption Data Groups as described +in chapter 9 “Transmission of caption and superimpose” of [@!ARIB.STD-B24], volume 1, part 3. +All of the Caption Statement Data Groups in a given Matroska Track MUST use the same language index.
+ +A Data Group is normally shown until a subsequent Group provides instructions to clear it. +Therefore the Matroska Block SHOULD NOT have a Duration. +A player SHOULD display a Data Group within a Matroska Block until its internal duration elapses, +or until a subsequent Data Group removes it.
+ +