- From: CVS User spfeiffe <cvsmail@w3.org>
- Date: Tue, 07 Apr 2015 23:40:51 +0000
- To: public-html-commits@w3.org
Update of /sources/public/html5/html-sourcing-inband-tracks
In directory roscoe:/var/tmp/cvs-serv3208
Modified Files:
Overview.html
Log Message:
Sync HTML sourcing inband tracks spec with Git commit 60e06975544156c18055739f9923a3c428ff90b9
--- /sources/public/html5/html-sourcing-inband-tracks/Overview.html 2015/02/15 10:14:18 1.11
+++ /sources/public/html5/html-sourcing-inband-tracks/Overview.html 2015/04/07 23:40:51 1.12
@@ -223,7 +223,7 @@
</p>
<h1 class="title p-name" id="title" property="dcterms:title">Sourcing In-band Media Resource Tracks from Media Containers into HTML</h1>
- <h2 id="unofficial-draft-15-february-2015">Unofficial Draft <time property="dcterms:issued" class="dt-published" datetime="2015-02-15">15 February 2015</time></h2>
+ <h2 id="unofficial-draft-07-april-2015">Unofficial Draft <time property="dcterms:issued" class="dt-published" datetime="2015-04-07">07 April 2015</time></h2>
<dl>
@@ -292,6 +292,8 @@
<p>
The specification maintains mappings from in-band audio, video and other data tracks of media resources to HTML <code>VideoTrack</code>, <code>AudioTrack</code>, and <code>TextTrack</code> objects and their attribute values.
</p>
+ <p>This specification defines the mapping of tracks from media resources depending on the MIME type of that resource. If an implementation claims to support that MIME type and exposes a track from a resource of that type, the exposed track must conform to this specification.</p>
+ <p>Which actual tracks are exposed by a user agent from a supported media resource is implementation dependent. A user agent may expose tracks, for which it supports parsing, decoding and rendering, for playback selection by the web application or user. A user agent may also decide to expose tracks coded in formats it is not able to decode, but which it can identify, and describe through metadata such as the HTML <code>kind</code> attribute and others as defined in this specification. For text tracks, the track content may be exposed to the Web application via TextTrackCue or DataCue objects.</p>
<p>
A generic rule to follow is that a track as exposed in HTML only ever represents a single semantic concept. When mapping from a media resource, sometimes an in-band track does not relate 1-to-1 to a HTML text, audio or video track.
</p>
@@ -311,9 +313,11 @@
</p>
<ol>
<li>Track order.
- <p>Tracks sourced according to this specification are referenced by HTML <code>TrackList</code> objects (<code>audioTracks</code>, <code>videoTracks</code> or <code>textTracks</code>). The [<cite><a class="bibref" href="#bib-HTML5">HTML5</a></cite>]/[<cite><a class="bibref" href="#bib-HTML">HTML</a></cite>] specification mandates that the tracks in those objects be consistently ordered. This requirement insures that the order of tracks is not changed when a track is added or removed, e.g. that <code>videoTracks[3]</code> points to the same object if the tracks with indices 0, 1, 2 and 3 were not removed. This also insures a deterministic result when calls to <code>getTrackById</code> are made with media resources, possibly invalid, that declares two tracks with the same id. This specification defines a consistent ordering of tracks between the media resource and <code>TrackList</code> objects when the media resource is consumed by the user agent. However, in some media workflows, the order of track in a media resource may be subject to changes (e.g. tracks may be added or removed) between authoring and publication. Applications associated with a media resource should not rely on this order of tracks being the same between when the media resource was authored and when it consumed by the user agent. All media resource formats used in this specification support identifying tracks using a unique identifier. This specification defines how those unique identifiers are mapped onto the <code>id</code> attribute of HTML Track objects. Application authors are encouraged to use the <code>id</code> attribute to identify tracks, rather than the index in a <code>TrackList</code> object.</p>
+ <p>Tracks sourced according to this specification are referenced by HTML <code>TrackList</code> objects (<code>audioTracks</code>, <code>videoTracks</code> or <code>textTracks</code>). The [<cite><a class="bibref" href="#bib-HTML5">HTML5</a></cite>]/[<cite><a class="bibref" href="#bib-HTML">HTML</a></cite>] specification mandates that the tracks in those objects be consistently ordered. This requirement insures that the order of tracks is not changed when a track is added or removed, e.g. that <code>videoTracks[3]</code> points to the same object if the tracks with indices 0, 1, 2 and 3 were not removed. This also insures a deterministic result when calls to <code>getTrackById</code> are made with media resources, possibly invalid, that declares two tracks with the same id. This specification defines a consistent ordering of tracks between the media resource and <code>TrackList</code> objects when the media resource is consumed by the user agent.</p>
+ <p>Note that in some media workflows, the order of tracks in a media resource may be subject to changes (e.g. tracks may be added or removed) between authoring and publication. Applications associated with a media resource should not rely on an order of tracks being the same between when the media resource was authored and when it is consumed by the user agent.</p>
+ <p>All media resource formats used in this specification support identifying tracks using a unique identifier. This specification defines how those unique identifiers are mapped onto the <code>id</code> attribute of HTML Track objects. Application authors are encouraged to use the <code>id</code> attribute to identify tracks, rather than the index in a <code>TrackList</code> object.</p>
</li>
- <li>How to identify the type of tracks.</li>
+ <li>How to identify the type of tracks - one of audio, video or text.</li>
<li>Setting the attributes <code>id</code>, <code>kind</code>, <code>language</code> and <code>label</code> for sourced <code>TextTrack</code> objects.</li>
<li>Setting the attributes <code>id</code>, <code>kind</code>, <code>language</code> and <code>label</code> for sourced <code>AudioTrack</code> and <code>VideoTrack</code> objects.</li>
<li>Mapping Text Track content into text track cues.</li>
@@ -324,7 +328,7 @@
<!--OddPage--><h2 id="h-mpegdash" resource="#h-mpegdash"><span property="xhv:role" resource="xhv:heading"><span class="secno">2. </span>MPEG DASH</span></h2>
<b>MIME type/subtype: <code>application/dash+xml</code></b>
<p>
- [<cite><a class="bibref" href="#bib-MPEGDASH">MPEGDASH</a></cite>] defines formats for a media manifest, called MPD (Media Presentation Description), which references media containers, called media segments. [<cite><a class="bibref" href="#bib-MPEGDASH">MPEGDASH</a></cite>] also defines some media segments formats based on [<cite><a class="bibref" href="#bib-MPEG2TS">MPEG2TS</a></cite>] or [<cite><a class="bibref" href="#bib-ISOBMFF">ISOBMFF</a></cite>]. Processing of media manifests and segments to expose tracks to Web applications can be done by the user agent. Alternatively, a web application can process the manifests and segments to expose tracks. When the user agent processes MPD and media segments directly, it exposes tracks for <code>AdaptationSet</code> and <code>ContentComponent</code> elements, as defined in this document. When the Web application processes the MPD and media segments, it passes media segments to the user agent according to the MediaSource Extension ([MSE]) specification. n this case, the tracks are exposed by the user agent according to MSE. The Web application may set default track attributes from MPD data, using the <code>trackDefaults</code> object, that will be used by the user agent to set attributes not set from initialization segment data.
+ [<cite><a class="bibref" href="#bib-MPEGDASH">MPEGDASH</a></cite>] defines formats for a media manifest, called MPD (Media Presentation Description), which references media containers, called media segments. [<cite><a class="bibref" href="#bib-MPEGDASH">MPEGDASH</a></cite>] also defines some media segments formats based on [<cite><a class="bibref" href="#bib-MPEG2TS">MPEG2TS</a></cite>] or [<cite><a class="bibref" href="#bib-ISOBMFF">ISOBMFF</a></cite>]. Processing of media manifests and segments to expose tracks to Web applications can be done by the user agent. Alternatively, a web application can process the manifests and segments to expose tracks. When the user agent processes MPD and media segments directly, it exposes tracks for <code>AdaptationSet</code> and <code>ContentComponent</code> elements, as defined in this document. When the Web application processes the MPD and media segments, it passes media segments to the user agent according to the MediaSource Extension [<cite><a class="bibref href="#bib-MSE">MSE</a></cite>] specification. In this case, the tracks are exposed by the user agent according to [<cite><a class="bibref" href="#bib-MSE">MSE</a></cite>]. The Web application may set default track attributes from MPD data, using the <code>trackDefaults</code> object, that will be used by the user agent to set attributes not set from initialization segment data.
</p>
<ol>
<li><p>Track Order</p>
@@ -335,11 +339,15 @@
<li><p>Determining the type of track</p>
<p>
- A user agent recognises and supports data from a MPEG DASH media resource as being equivalent to a HTML track based on the AdaptationSet or ContentComponent mimeType:
+ A user agent recognises and supports data from a MPEG DASH media resource as being equivalent to a HTML track based on the <code>AdaptationSet</code> or <code>ContentComponent</code> <code>mimeType</code>:
</p>
<ul>
- <li>text track: the <code>mimeType</code> is of main type "<code>application</code>" or "<code>text</code>"</li>
- <li>video track: the <code>mimeType</code> is of main type "<code>video</code>"</li>
+ <li>text track:
+ <ul>
+ <li>the <code>AdaptationSet mimeType</code> is of main type "<code>application</code>" or "<code>text</code>"</li>
+ <li>the <code>AdaptationSet mimeType</code> is of main type "<code>video</code>" and the <code>AdaptationSet</code> contains one or more <a href="#mp4avcceacaption">ISOBMFF CEA 608 or 708 caption services</a>.</li>
+ </ul>
+ </li><li>video track: the <code>mimeType</code> is of main type "<code>video</code>"</li>
<li>audio track: the <code>mimeType</code> is of main type "<code>audio</code>"</li>
</ul>
</li>
@@ -356,17 +364,25 @@
<tbody><tr>
<th><code>id</code></th>
<td>
- Content of the <code>id</code> attribute in the <code>AdaptationSet</code> or <code>ContentComponent</code> element. Empty string if <code>id</code> attribute is not present.
+ The track is:
+ <ul>
+ <li>An <a href="#mp4avcceacaption">ISOBMFF CEA 608 caption service</a>: value of the '<code>channel-number</code>' field in the <code>Accessibility</code> descriptor in the <code>AdaptationSet</code>.</li>
+ <li>An <a href="#mp4avcceacaption">ISOBMFF CEA 708 caption service</a>: value of the '<code>service-number</code>' field in the <code>Accessibility</code> descriptor in the <code>AdaptationSet</code>.</li>
+ <li>Otherwise, the content of the '<code>id</code>' attribute in the <code>AdaptationSet</code> or <code>ContentComponent</code> element. Empty string if '<code>id</code>' attribute is not present.</li>
+ </ul>
</td>
</tr>
<tr>
<th><code>kind</code></th>
- <td>
- <p>Given URN="<code>urn:mpeg:dash:role:2011</code>":</p>
+ <td>The track:
<ul>
- <li>"<code>captions</code>": if the <code>Role</code> descriptor's value is "<code>caption</code>"</li>
- <li>"<code>subtitles</code>": if the <code>Role</code> descriptor's value is "<code>subtitle</code>"</li>
- <li>"<code>metadata</code>": otherwise</li>
+ <li>Represents an <code>AdaptationSet</code> containing a <code>Role</code> descriptor with <code>schemeIdURI</code> attribute = "<code>urn:mpeg:dash:role:2011</code>":
+ <ul>
+ <li>"<code>captions</code>": if the <code>Role</code> descriptor's value is "<code>caption</code>"</li>
+ <li>"<code>subtitles</code>": if the <code>Role</code> descriptor's value is "<code>subtitle</code>"</li>
+ <li>"<code>metadata</code>": otherwise</li>
+ </ul></li>
+ <li>Is an <a href="#mp4avcceacaption">ISOBMFF CEA 608 or 708 caption service</a>: "<code>captions</code>".</li>
</ul>
</td>
</tr>
@@ -378,14 +394,17 @@
</tr>
<tr>
<th><code>language</code></th>
- <td>
- Content of the <code>lang</code> attribute in the <code>AdaptationSet</code> or <code>ContentComponent</code> element.
+ <td>The track is:
+ <ul>
+ <li>An <a href="#mp4avcceacaption">ISOBMFF CEA 608 708 caption service</a>: the value of the '<code>language</code>' field in the <code>Accessibility</code> descriptor, in the <code>AdaptationSet</code>, where the corresponding '<code>channel-number</code>' or '<code>service-number</code>' is the same as this track's '<code>id</code>' attribute. The empty string if there is no such corresponding '<code>channel-number</code>' or '<code>service-number</code>'.</li>
+ <li>Otherwise: the content of the '<code>lang</code>'ßß attribute in the <code>AdaptationSet</code> or <code>ContentComponent</code> element.</li>
+ </ul>
</td>
</tr>
<tr>
<th><code>inBandMetadataTrackDispatchType</code></th>
<td>
- If <code>kind</code> is "<code>metadata</code>" the concatenation of the <code>AdaptationSet</code> element and all child <code>Role</code> descriptors. The empty string otherwise.
+ If <code>kind</code> is "<code>metadata</code>", the concatenation of the <code>AdaptationSet</code> element and all child <code>Role</code> descriptors. The empty string otherwise.
</td>
</tr>
<tr>
@@ -453,7 +472,7 @@
Media content with the MIME type "<code>text/vtt</code>" is in the WebVTT format and should be exposed as a <code>VTTCue</code> object as defined in [<cite><a class="bibref" href="#bib-WEBVTT">WEBVTT</a></cite>].
</p>
<p>
- Media content with the MIME type "<code>application/ttml+xml</code>" is in the TTML format and should be exposed as an as yet to be defined <code>TTMLCue</code> object. Alternatively, browsers can also map the TTML features to <code>VTTCue</code> objects. Finally, browsers that cannot render TTML [<cite><a class="bibref" href="#bib-ttaf1-dfxp">ttaf1-dfxp</a></cite>] format data should expose them as <code>DataCue</code> objects [<cite><a class="bibref" href="#bib-HTML5">HTML5</a></cite>]. In this case, the TTML file must be parsed in its entirety and then converted into a sequence of TTML Intermediate Synchronic Documents (ISDs). Each ISD creates a <code>DataCue</code> object with attributes sourced as follows:
+ Media content with the MIME type "<code>application/ttml+xml</code>" is in the TTML format and should be exposed as an as yet to be defined <code>TTMLCue</code> object. Alternatively, browsers can also map the TTML features to <code>VTTCue</code> objects [<cite><a class="bibref" href="#bib-WEBVTT">WEBVTT</a></cite>]. Finally, browsers that cannot render TTML [<cite><a class="bibref" href="#bib-ttaf1-dfxp">ttaf1-dfxp</a></cite>] format data should expose them as <code>DataCue</code> objects [<cite><a class="bibref" href="#bib-HTML51">HTML51</a></cite>]. In this case, the TTML file must be parsed in its entirety and then converted into a sequence of TTML Intermediate Synchronic Documents (ISDs). Each ISD creates a <code>DataCue</code> object with attributes sourced as follows:
</p><p>
</p><table>
<thead>
@@ -525,7 +544,7 @@
<li>For <code>stream_type</code> 0x1B, the presence of caption data in the <code>ATSC1_data()</code> field [<cite><a class="bibref" href="#bib-SCTE128-1">SCTE128-1</a></cite>].</li>
</ul>
</li>
- <li>a DVB subtitle component [<cite><a class="bibref" href="#bib-DVB-SUB">DVB-SUB</a></cite>] as identified by a <code>subtitling_descriptor</code> [<cite><a class="bibref" href="#bib-DVB-SI">DVB-SI</a></cite>]in the 'Elementary Stream Descriptors' in the PMT entry for a stream with a <code>stream_type</code> of "0x06"</li>
+ <li>a DVB subtitle component [<cite><a class="bibref" href="#bib-DVB-SUB">DVB-SUB</a></cite>] as identified by a <code>subtitling_descriptor</code> [<cite><a class="bibref" href="#bib-DVB-SI">DVB-SI</a></cite>] in the 'Elementary Stream Descriptors' in the PMT entry for a stream with a <code>stream_type</code> of "0x06"</li>
<li>an ITU-R System B Teletext component [<cite><a class="bibref" href="#bib-DVB-TXT">DVB-TXT</a></cite>] as identified by an <code>teletext_descriptor</code> [<cite><a class="bibref" href="#bib-DVB-SI">DVB-SI</a></cite>] in the 'Elementary Stream Descriptors' in the PMT entry for a stream with a <code>stream_type</code> of "0x06"</li>
<li>a VBI data component [<cite><a class="bibref" href="#bib-DVB-VBI">DVB-VBI</a></cite>] as identified by a <code>VBI_data_descriptor</code> [<cite><a class="bibref" href="#bib-DVB-SI">DVB-SI</a></cite>] or a <code>VBI_teletext_descriptor</code> [<cite><a class="bibref" href="#bib-DVB-SI">DVB-SI</a></cite>] in the 'Elementary Stream Descriptors' in the PMT entry for a stream with a <code>stream_type</code> of "0x06"</li>
</ul>
@@ -552,7 +571,7 @@
<td>
Decimal representation of the elementary stream's identifier (<code>elementary_PID</code> field) in the PMT.
<p>
- In the case of CEA 708 closed captions, decimal representation of the <code>caption_service_number</code> in the 'Caption Service Descriptor' in the PMT.
+ In the case of CEA 708 closed captions, decimal representation of the <code>service_number</code> field in the 'Caption Channel Service Block'.
</p>
<p>
If program 0 (zero) is present in the transport stream, a string of the format "OOOO.TTTT.SSSS.CC" consisting of the following, lower-case hexadecimal encoded fields:
@@ -750,7 +769,7 @@
<ol type="a">
<li><p>Metadata cues</p>
<p>
- Cues on an MPEG-2 metadata text track are created as <code>DataCue</code> objects [<cite><a class="bibref" href="#bib-HTML5">HTML5</a></cite>]. Each <code>section</code> in an elementary stream identified as a text track creates a <code>DataCue</code> object with its <code>TextTrackCue</code> attributes sourced as follows:
+ Cues on an MPEG-2 metadata text track are created as <code>DataCue</code> objects [<cite><a class="bibref" href="#bib-HTML51">HTML51</a></cite>]. Each <code>section</code> in an elementary stream identified as a text track creates a <code>DataCue</code> object with its <code>TextTrackCue</code> attributes sourced as follows:
</p>
<table>
<thead>
@@ -790,7 +809,7 @@
</p><ul>
<li>CEA 708
<p>
- MPEG-2 TS captions in the CEA 708 format [<cite><a class="bibref" href="#bib-CEA708">CEA708</a></cite>] are carried in the video stream in Picture User Data [<cite><a class="bibref" href="#bib-ATSC53-4">ATSC53-4</a></cite>] for <code>stream_type</code> 0x02 and in Supplemental Enhancement Information [<cite><a class="bibref" href="#bib-ATSC72-1">ATSC72-1</a></cite>] for <code>stream_type</code> 0x1B. Browsers that can render the CEA 708 format should expose them in as yet to be specified <code>CEA708Cue</code> objects. Alternatively, browsers can also map the CEA 708 features to <code>VTTCue</code> objects [<cite><a class="bibref" href="#bib-VTT708">VTT708</a></cite>]. Finally, browsers that cannot render CEA 708 captions should expose them as <code>DataCue</code> objects [<cite><a class="bibref" href="#bib-HTML5">HTML5</a></cite>]. In this case, each <code>service_block</code> in a digital TV closed caption (DTVCC) transport channel creates a <code>DataCue</code> object with <code>TextrackCue</code> attributes sourced as follows:
+ MPEG-2 TS captions in the CEA 708 format [<cite><a class="bibref" href="#bib-CEA708">CEA708</a></cite>] are carried in the video stream in Picture User Data [<cite><a class="bibref" href="#bib-ATSC53-4">ATSC53-4</a></cite>] for <code>stream_type</code> 0x02 and in Supplemental Enhancement Information [<cite><a class="bibref" href="#bib-ATSC72-1">ATSC72-1</a></cite>] for <code>stream_type</code> 0x1B. Browsers that can render the CEA 708 format should expose them in as yet to be specified <code>CEA708Cue</code> objects. Alternatively, browsers can also map the CEA 708 features to <code>VTTCue</code> objects [<cite><a class="bibref" href="#bib-VTT708">VTT708</a></cite>]. Finally, browsers that cannot render CEA 708 captions should expose them as <code>DataCue</code> objects [<cite><a class="bibref" href="#bib-HTML51">HTML51</a></cite>]. In this case, each <code>service_block</code> in a digital TV closed caption (DTVCC) transport channel creates a <code>DataCue</code> object with <code>TetTrackCue</code> attributes sourced as follows:
</p>
<table>
<thead>
@@ -838,7 +857,7 @@
<ul>
<li>SCTE 27
<p>
- MPEG-2 TS subtitles in the SCTE 27 format [<cite><a class="bibref" href="#bib-SCTE27">SCTE27</a></cite>] should should be exposed in an as yet to be specified <code>SCTE27Cue</code> objects. Alternatively, browsers can also map the SCTE 27 features to <code>VTTCue</code> object via an as yet to be specified mapping process. Finally, browsers that cannot render SCTE 27 subtitles, should expose them as <code>DataCue</code> objects [<cite><a class="bibref" href="#bib-HTML5">HTML5</a></cite>]. In this case, each <code>section</code> in an elementary stream identified as a subtitles text track creates a <code>DataCue</code> object with <code>TextTrackCue</code> attributes sourced as follows:
+ MPEG-2 TS subtitles in the SCTE 27 format [<cite><a class="bibref" href="#bib-SCTE27">SCTE27</a></cite>] should should be exposed in an as yet to be specified <code>SCTE27Cue</code> objects. Alternatively, browsers can also map the SCTE 27 features to <code>VTTCue</code> object via an as yet to be specified mapping process. Finally, browsers that cannot render SCTE 27 subtitles, should expose them as <code>DataCue</code> objects [<cite><a class="bibref" href="#bib-HTML51">HTML51</a></cite>]. In this case, each <code>section</code> in an elementary stream identified as a subtitles text track creates a <code>DataCue</code> object with <code>TextTrackCue</code> attributes sourced as follows:
</p>
<table>
<thead>
@@ -904,8 +923,12 @@
A user agent recognises and supports data from a <code>TrackBox</code> as being equivalent to a HTML track based on the value of the <code>handler_type</code> field in the <code>HandlerBox</code> (<code>hdlr</code>) of the <code>MediaBox</code> (<code>mdia</code>) of the <code>TrackBox</code>:
</p>
<ul>
- <li>text track: the <code>handler_type</code> value is "<code>meta</code>", "<code>subt</code>" or "<code>text</code>"</li>
- <li>video track: the <code>handler_type</code> value is "<code>vide</code>"</li>
+ <li>text track:
+ <ul>
+ <li>the <code>handler_type</code> value is "<code>meta</code>", "<code>subt</code>" or "<code>text</code>"</li>
+ <li>the <code>handler_type</code> value is "<code>vide</code>" and an <dfn id="mp4avcceacaption"> ISOBMFF CEA 608 or 708 caption service </dfn> is encapsulated in the video track as an SEI message as defined in [<cite><a class="bibref" href="#bib-DASHIFIOP">DASHIFIOP</a></cite>].</li>
+ </ul>
+ </li><li>video track: the <code>handler_type</code> value is "<code>vide</code>"</li>
<li>audio track: the <code>handler_type</code> value is "<code>soun</code>"</li>
</ul>
</li>
@@ -919,7 +942,10 @@
<tbody><tr>
<th><code>id</code></th>
<td>
- Decimal representation of the <code>track_ID</code> of a <code>TrackHeaderBox</code> (<code>tkhd</code>) in a <code>TrackBox</code> (<code>trak</code>).
+ If the track is an <a href="#mp4avcceacaption">ISOBMFF CEA 608 or 708 caption service</a> then the concatenation of the string "cc" and the string representation of the channel number for a CEA 608 caption or the string representation of the <code>"service_number"</code> in the Caption Channel Service Block for a CEA 708 caption.
+ <p>
+ Otherwise, the decimal representation of the <code>track_ID</code> of a <code>TrackHeaderBox</code> (<code>tkhd</code>) in a <code>TrackBox</code> (<code>trak</code>).
+ </p>
</td>
</tr>
<tr>
@@ -930,18 +956,19 @@
<ul>
<li><dfn id="WebVTTcaption">WebVTT caption</dfn>: <code>handler_type</code> is "<code>text</code>" and <code>SampleEntry</code> format is <code>WVTTSampleEntry</code> [<cite><a class="bibref" href="#bib-ISO14496-30">ISO14496-30</a></cite>] and the VTT metadata header <code>Kind</code> is "<code>captions</code>"</li>
<li><dfn id="SMPTETTcaption">SMPTE-TT caption</dfn>: <code>handler_type</code> is "<code>subt</code>" and <code>SampleEntry</code> format is <code>XMLSubtitleSampleEntry</code> [<cite><a class="bibref" href="#bib-ISO14496-30">ISO14496-30</a></cite>] and the <code>namespace</code> is set to "<code>http://www.smpte-ra.org/schemas/2052-1/2013/smpte-tt#cea708</code>" [<cite><a class="bibref" href="#bib-SMPTE2052-11">SMPTE2052-11</a></cite>].</li>
- <li></li><li><dfn id="3GPPcaption">3GPP caption</dfn>: <code>handler_type</code> is "<code>text</code>" and the <code>SampleEntry</code> code (<code>format</code> field) is "<code>tx3g</code>". <div class="note"><div class="note-title" aria-level="3" role="heading" id="h-note7"><span>Note</span></div><p class="">Are all sample entries of this type "<code>captions</code>"?</p></div></li>
+ <li>An <a href="#mp4avcceacaption">ISOBMFF CEA 608 or 708 caption service</a>.</li>
+ <li><dfn id="3GPPcaption">3GPP caption</dfn>: <code>handler_type</code> is "<code>text</code>" and the <code>SampleEntry</code> code (<code>format</code> field) is "<code>tx3g</code>". <div class="note"><div class="note-title" aria-level="3" role="heading" id="h-note7"><span>Note</span></div><p class="">Are all sample entries of this type "<code>captions</code>"?</p></div></li>
</ul>
</li>
- <li>"subtitles":
+ <li>"<code>subtitles<code>":
<ul>
<li><dfn id="WebVTTsubtitle">WebVTT subtitle</dfn>: <code>handler_type</code> is "<code>text</code>" and <code>SampleEntry</code> format is <code>WVTTSampleEntry</code> [<cite><a class="bibref" href="#bib-ISO14496-30">ISO14496-30</a></cite>] and the VTT metadata header <code>Kind</code> is "<code>subtitles</code>"</li>
<li><dfn id="SMPTE-TT subtitle">SMPTE-TT subtitle</dfn>: <code>handler_type</code> is "<code>subt</code>" and <code>SampleEntry</code> format is <code>XMLSubtitleSampleEntry</code> [<cite><a class="bibref" href="#bib-ISO14496-30">ISO14496-30</a></cite>] and the <code>namespace</code> is set to a TTML namespace that does not indicate a <a href="#SMPTETTcaption">SMPTE-TT caption</a>.</li>
</ul>
- </li>
+ </code></code></li><code><code>
<li>"<code>metadata</code>": otherwise</li>
- </ul>
- </td>
+ </code></code></ul><code><code>
+ </code></code></td>
</tr>
<tr>
<th><code>label</code></th>
@@ -952,7 +979,13 @@
<tr>
<th><code>language</code></th>
<td>
- Content of the <code>language</code> field in the <code>MediaHeaderBox</code>.
+ If the track is an <a href="#mp4avcceacaption">ISOBMFF CEA 608 or 708 caption service</a> then the empty string ("").
+ <p>
+ Otherwise, the content of the <code>language</code> field in the <code>MediaHeaderBox</code>.
+ </p>
+ <div class="note"><div class="note-title" aria-level="3" role="heading" id="h-note8"><span>Note</span></div><p class="">
+ No signaling is currently defined for specifying the langaugae of CEA 608 or 708 captions in ISOBMFF. MPEG DASH MPDs may specify caption track metadata, including language [<cite><a class="bibref" href="#bib-DASHIFIOP">DASHIFIOP</a></cite>]. The user agent should set the <code>language</code> attribute of CEA 608 or 708 caption text tracks to the empty string so that script may use the media source extensions [<cite><a class="bibref" href="#bib-MSE">MSE</a></cite>] <code>TrackDefault</code> object to provide a default for the <code>language</code> attribute.
+ </p></div>
</td>
</tr>
<tr>
@@ -1081,7 +1114,7 @@
</tbody></table>
<p></p>
<p>
- ISOBMFF text tracks carry TTML data if the media handler type is "<code>subt</code>" and an <code>XMLSubtileSampleEntry</code> format is used with a TTML-based <code>name_space</code> field, as described in [<cite><a class="bibref" href="#bib-ISO14496-30">ISO14496-30</a></cite>]. Browsers that can render text tracks in the TTML format should expose an as yet to be defined <code>TTMLCue</code>. Alternatively, browsers can also map the TTML features to <code>VTTCue</code> objects. Finally, browsers that cannot render TTML [<cite><a class="bibref" href="#bib-ttaf1-dfxp">ttaf1-dfxp</a></cite>] format data should expose them as <code>DataCue</code> objects [<cite><a class="bibref" href="#bib-HTML5">HTML5</a></cite>]. Each TTML subtitle sample consists of an XML document and creates a <code>DataCue</code> object with attributes sourced as follows:
+ ISOBMFF text tracks carry TTML data if the media handler type is "<code>subt</code>" and an <code>XMLSubtileSampleEntry</code> format is used with a TTML-based <code>name_space</code> field, as described in [<cite><a class="bibref" href="#bib-ISO14496-30">ISO14496-30</a></cite>]. Browsers that can render text tracks in the TTML format should expose an as yet to be defined <code>TTMLCue</code>. Alternatively, browsers can also map the TTML features to <code>VTTCue</code> objects. Finally, browsers that cannot render TTML [<cite><a class="bibref" href="#bib-ttaf1-dfxp">ttaf1-dfxp</a></cite>] format data should expose them as <code>DataCue</code> objects [<cite><a class="bibref" href="#bib-HTML51">HTML51</a></cite>]. Each TTML subtitle sample consists of an XML document and creates a <code>DataCue</code> object with attributes sourced as follows:
</p><p>
</p><table>
<thead>
@@ -1205,7 +1238,7 @@
<p>
Tracks of <code>kind</code> "<code>chapters</code>" are found in the "<code>Chapters</code>" section of the WebM file Segment, which are all at the beginning of the WebM file, such that chapters can be used for navigation. The details of this mapping have not been specified yet and simply point to the more powerful Matroska chapter specification [<cite><a class="bibref" href="#bib-Matroska">Matroska</a></cite>]. Presumably, the <code>id</code> attribute could be found in <code>EditionUID</code>, <code>label</code> is empty, and <code>language</code> can come from the first ChapterAtom's <code>ChapLanguage</code> value.
</p>
- <div class="note"><div class="note-title" aria-level="3" role="heading" id="h-note8"><span>Note</span></div><p class="">
+ <div class="note"><div class="note-title" aria-level="3" role="heading" id="h-note9"><span>Note</span></div><p class="">
The Matroska container format, which is the basis for WebM, has specifications for other text tracks, in particular SRT, SSA/ASS, and VOBSUB. The described attribute mappings can be applied to these, too, except that the <code>kind</code> field will always be "<code>subtitles</code>". The information of their <code>CodecPrivate</code> field is exposed in the <code>inBandMetadataTrackDispatchType</code> attribute.
</p></div>
</li>
@@ -1298,7 +1331,7 @@
</td>
</tr>
</tbody></table>
- <div class="note"><div class="note-title" aria-level="3" role="heading" id="h-note9"><span>Note</span></div><p class="">Other Matroska container format's text tracks can also be mapped to <code>TextTrackCue</code> objects. These will be created as <code>DataCue</code> objects [<cite><a class="bibref" href="#bib-HTML5">HTML5</a></cite>] with <code>id</code>, <code>startTime</code>, <code>endTime</code>, and <code>pauseOnExit</code> attributes filled identically to the <code>VTTCue</code> objects, and the <code>data</code> attribute containing the Block's data.
+ <div class="note"><div class="note-title" aria-level="3" role="heading" id="h-note10"><span>Note</span></div><p class="">Other Matroska container format's text tracks can also be mapped to <code>TextTrackCue</code> objects. These will be created as <code>DataCue</code> objects [<cite><a class="bibref" href="#bib-HTML51">HTML51</a></cite>] with <code>id</code>, <code>startTime</code>, <code>endTime</code>, and <code>pauseOnExit</code> attributes filled identically to the <code>VTTCue</code> objects, and the <code>data</code> attribute containing the Block's data.
</p></div>
</li>
</ol>
@@ -1419,7 +1452,7 @@
<tr>
<th><code>label</code></th>
<td>
- Content of the <<code>title</code> message header field of the fisbone header. If no Skeleton header is available, the empty string.
+ Content of the <code>title</code> message header field of the fisbone header. If no Skeleton header is available, the empty string.
</td>
</tr>
<tr>
@@ -1454,6 +1487,7 @@
</dd><dt id="bib-ATSC65">[ATSC65]</dt><dd><a href="http://www.atsc.org/cms/standards/A65_2013.pdf" property="dc:references"><cite>Program and System Information Protocol for Terrestrial Broadcast and Cable</cite></a>. 7 August 2013. URL: <a href="http://www.atsc.org/cms/standards/A65_2013.pdf" property="dc:references">http://www.atsc.org/cms/standards/A65_2013.pdf</a>
</dd><dt id="bib-ATSC72-1">[ATSC72-1]</dt><dd><a href="http://www.atsc.org/cms/standards/a72/A72-Part-1-2014.pdf" property="dc:references"><cite>Video System Characteristics of AVC in the ATSC Digital Television System</cite></a>. 18 February 2014. URL: <a href="http://www.atsc.org/cms/standards/a72/A72-Part-1-2014.pdf" property="dc:references">http://www.atsc.org/cms/standards/a72/A72-Part-1-2014.pdf</a>
</dd><dt id="bib-CEA708">[CEA708]</dt><dd><a href="http://www.ce.org/Standards/Standard-Listings/R4-3-Television-Data-Systems-Subcommittee/CEA-708-D.aspx" property="dc:references"><cite>Digital Television (DTV) Closed Captioning CEA-708-B</cite></a>. URL: <a href="http://www.ce.org/Standards/Standard-Listings/R4-3-Television-Data-Systems-Subcommittee/CEA-708-D.aspx" property="dc:references">http://www.ce.org/Standards/Standard-Listings/R4-3-Television-Data-Systems-Subcommittee/CEA-708-D.aspx</a>
+</dd><dt id="bib-DASHIFIOP">[DASHIFIOP]</dt><dd><a href="http://dashif.org/w/2014/08/DASH-IF-IOP-v2.90.pdf" property="dc:references"><cite>Guidelines for Implementation: DASH-IF Interoperability Points</cite></a>. Community Review. URL: <a href="http://dashif.org/w/2014/08/DASH-IF-IOP-v2.90.pdf" property="dc:references">http://dashif.org/w/2014/08/DASH-IF-IOP-v2.90.pdf</a>
</dd><dt id="bib-DVB-SI">[DVB-SI]</dt><dd><a href="http://www.etsi.org/deliver/etsi_en/300400_300499/300468/01.14.01_60/en_300468v011401p.pdf" property="dc:references"><cite>ETSI EN 300 468: "Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems"</cite></a>. URL: <a href="http://www.etsi.org/deliver/etsi_en/300400_300499/300468/01.14.01_60/en_300468v011401p.pdf" property="dc:references">http://www.etsi.org/deliver/etsi_en/300400_300499/300468/01.14.01_60/en_300468v011401p.pdf</a>
</dd><dt id="bib-DVB-SUB">[DVB-SUB]</dt><dd><a href="http://www.etsi.org/deliver/etsi_en/300700_300799/300743/01.05.01_60/en_300743v010501p.pdf" property="dc:references"><cite>ETSI EN 300 743: "Digital Video Broadcasting (DVB); Subtitling systems"</cite></a>. URL: <a href="http://www.etsi.org/deliver/etsi_en/300700_300799/300743/01.05.01_60/en_300743v010501p.pdf" property="dc:references">http://www.etsi.org/deliver/etsi_en/300700_300799/300743/01.05.01_60/en_300743v010501p.pdf</a>
</dd><dt id="bib-DVB-TXT">[DVB-TXT]</dt><dd><a href="http://www.etsi.org/deliver/etsi_en/300400_300499/300472/01.03.01_60/en_300472v010301p.pdf" property="dc:references"><cite>ETSI EN 300 472: "Digital Video Broadcasting (DVB); Specification for conveying ITU-R System B Teletext in DVB bitstreams"</cite></a>. URL: <a href="http://www.etsi.org/deliver/etsi_en/300400_300499/300472/01.03.01_60/en_300472v010301p.pdf" property="dc:references">http://www.etsi.org/deliver/etsi_en/300400_300499/300472/01.03.01_60/en_300472v010301p.pdf</a>
@@ -1461,10 +1495,12 @@
</dd><dt id="bib-ETSI102366">[ETSI102366]</dt><dd><a href="http://www.etsi.org/deliver/etsi_ts/102300_102399/102366/01.03.01_60/ts_102366v010301p.pdf" property="dc:references"><cite>Digital Audio Compression(AC-3, Enhanced AC-3) Standard v1.3.1</cite></a>. URL: <a href="http://www.etsi.org/deliver/etsi_ts/102300_102399/102366/01.03.01_60/ts_102366v010301p.pdf" property="dc:references">http://www.etsi.org/deliver/etsi_ts/102300_102399/102366/01.03.01_60/ts_102366v010301p.pdf</a>
</dd><dt id="bib-HTML">[HTML]</dt><dd>Ian Hickson. <a href="https://html.spec.whatwg.org/" property="dc:references"><cite>HTML</cite></a>. Living Standard. URL: <a href="https://html.spec.whatwg.org/" property="dc:references">https://html.spec.whatwg.org/</a>
</dd><dt id="bib-HTML5">[HTML5]</dt><dd>Ian Hickson; Robin Berjon; Steve Faulkner; Travis Leithead; Erika Doyle Navara; Edward O'Connor; Silvia Pfeiffer. <a href="http://www.w3.org/TR/html5/" property="dc:references"><cite>HTML5</cite></a>. 28 October 2014. W3C Recommendation. URL: <a href="http://www.w3.org/TR/html5/" property="dc:references">http://www.w3.org/TR/html5/</a>
+</dd><dt id="bib-HTML51">[HTML51]</dt><dd>Ian Hickson; Robin Berjon; Steve Faulkner; Travis Leithead; Erika Doyle Navara; Edward O'Connor; Tab Atkins Jr.; Simon Pieters; Yoav Weiss; Marcos Caceres; Mathew Marquis. <a href="http://www.w3.org/TR/html51/" property="dc:references"><cite>HTML 5.1</cite></a>. 23 March 2015. W3C Working Draft. URL: <a href="http://www.w3.org/TR/html51/" property="dc:references">http://www.w3.org/TR/html51/</a>
</dd><dt id="bib-ISO14496-30">[ISO14496-30]</dt><dd><a href="http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=63107" property="dc:references"><cite>Information technology — Coding of audio-visual objects — Part 30: Timed text and other visual overlays in ISO base media file format</cite></a>. 11 March 2014. URL: <a href="http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=63107" property="dc:references">http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=63107</a>
</dd><dt id="bib-ISOBMFF">[ISOBMFF]</dt><dd><a href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c061988_ISO_IEC_14496-12_2012.zip" property="dc:references"><cite>Information technology -- Coding of audio-visual objects -- Part 12: ISO base media file format</cite></a> ISO/IEC 14496-12:2012. URL: <a href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c061988_ISO_IEC_14496-12_2012.zip" property="dc:references">http://standards.iso.org/ittf/PubliclyAvailableStandards/c061988_ISO_IEC_14496-12_2012.zip</a>
</dd><dt id="bib-MPEG2TS">[MPEG2TS]</dt><dd><a href="http://www.itu.int/rec/T-REC-H.222.0-201206-I" property="dc:references"><cite>Information technology -- Generic coding of moving pictures and associated audio information: Systems ITU-T Rec. H.222.0 / ISO/IEC 13818-1:2013</cite></a>. URL: <a href="http://www.itu.int/rec/T-REC-H.222.0-201206-I" property="dc:references">http://www.itu.int/rec/T-REC-H.222.0-201206-I</a>
</dd><dt id="bib-MPEGDASH">[MPEGDASH]</dt><dd><a href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c065274_ISO_IEC_23009-1_2014.zip" property="dc:references"><cite>ISO/IEC 23009-1:2014 Information technology -- Dynamic adaptive streaming over HTTP (DASH) -- Part 1: Media presentation description and segment formats</cite></a>. URL: <a href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c065274_ISO_IEC_23009-1_2014.zip" property="dc:references">http://standards.iso.org/ittf/PubliclyAvailableStandards/c065274_ISO_IEC_23009-1_2014.zip</a>
+</dd><dt id="bib-MSE">[MSE]</dt><dd>Aaron Colwell; Adrian Bateman; Mark Watson. <a href="http://www.w3.org/TR/media-source/" property="dc:references"><cite>Media Source Extensions</cite></a>. 31 March 2015. W3C Candidate Recommendation. URL: <a href="http://www.w3.org/TR/media-source/" property="dc:references">http://www.w3.org/TR/media-source/</a>
</dd><dt id="bib-Matroska">[Matroska]</dt><dd><a href="http://matroska.org/technical/specs/index.html" property="dc:references"><cite>Matroska Specifications</cite></a>. 9 January 2014. URL: <a href="http://matroska.org/technical/specs/index.html" property="dc:references">http://matroska.org/technical/specs/index.html</a>
</dd><dt id="bib-OGG">[OGG]</dt><dd>S. Pfeiffer. <a href="https://tools.ietf.org/html/rfc3533" property="dc:references"><cite>The Ogg Encapsulation Format Version 0</cite></a>. May 2003. Informational. URL: <a href="https://tools.ietf.org/html/rfc3533" property="dc:references">https://tools.ietf.org/html/rfc3533</a>
</dd><dt id="bib-OGGSKELETON">[OGGSKELETON]</dt><dd><a href="http://wiki.xiph.org/SkeletonHeaders" property="dc:references"><cite>Ogg Skeleton 4 Message Headers</cite></a>. 17 March 2014. URL: <a href="http://wiki.xiph.org/SkeletonHeaders" property="dc:references">http://wiki.xiph.org/SkeletonHeaders</a>
Received on Tuesday, 7 April 2015 23:40:57 UTC