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[Bug 13359] New: An way is needed to identify the type of data in a track alement

From: <bugzilla@jessica.w3.org>
Date: Mon, 25 Jul 2011 22:29:57 +0000
To: public-html-bugzilla@w3.org
Message-ID: <bug-13359-2486@http.www.w3.org/Bugs/Public/>

           Summary: An way is needed to identify the type of data in a
                    track alement
           Product: HTML WG
           Version: unspecified
          Platform: PC
        OS/Version: Windows XP
            Status: NEW
          Severity: normal
          Priority: P2
         Component: HTML5 spec (editor: Ian Hickson)
        AssignedTo: ian@hixie.ch
        ReportedBy: b.lund@cablelabs.com
         QAContact: public-html-bugzilla@w3.org
                CC: mike@w3.org, public-html-wg-issue-tracking@w3.org,

Problem Statement

HTML5 provides access to timed text tracks and its constituent data via the
TextTrack and TextTrackCue interfaces for the purpose of allowing (1) script
control over showing or hiding the associated track content via TextTrack.mode,
and (2) script access to the constituent track data (as cues) via
TextTrack.getCueAsSource(). In order for application authored script to (1)
make decisions about showing/hiding track content and (2) interpret the raw
source content, it is necessary to provide the script with additional
information about the form of the track content. In the case where
TextTrack.kind == “metadata” it is also necessary to provide the script with
information about the purpose of the track. At present, the only information
provided is via TextTrack.kind and TextTrack.label; however, this information
is insufficient to determine the form of the track content since it does not
identify the media type or the purpose of the track for metatdata tracks. For
example, if TextTrack.kind == 'metadata', then the track content may contain
ETV EISS data [1], Ad insertion data (SCTE-35) [2], generic XML data, etc. 
Similarly, if TextTrack.kind == 'captions', then the track content may contain
WebVTT data [3], Timed Text (TTML) data [4], CEA-708 data [5], etc.

Proposed Solution

In order to resolve the above problem, it is proposed that a @type attribute be
added to the track element and an associated IDL attribute be added to the
TextTrack interface. When specified by the content author, this media type
attribute would serve as a hint to application script as to the media type
employed for the track content.

[1] http://www.cablelabs.com/specifications/OC-SP-ETV-AM1.0-I06-110128.pdf
[2] http://www.scte.org/standards/Standards_Available.aspx
[3] http://www.whatwg.org/specs/web-apps/current-work/webvtt.html
[4] http://www.w3.org/TR/ttaf1-dfxp/
[5] http://www.ce.org/Standards/listings.asp

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Received on Monday, 25 July 2011 22:29:59 UTC

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