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[Bug 13359] A way is needed to identify the type of data in a track element

From: <bugzilla@jessica.w3.org>
Date: Fri, 19 Aug 2011 22:18:05 +0000
To: public-html-a11y@w3.org
Message-Id: <E1QuXO9-000708-ME@jessica.w3.org>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=13359

--- Comment #4 from Bob Lund <b.lund@cablelabs.com> 2011-08-19 22:18:04 UTC ---
(In reply to comment #3)
> (In reply to comment #2)
> > EDITOR'S RESPONSE: This is an Editor's Response to your comment. If you are
> > satisfied with this response, please change the state of this bug to CLOSED. If
> > you have additional information and would like the editor to reconsider, please
> > reopen this bug. If you would like to escalate the issue to the full HTML
> > Working Group, please add the TrackerRequest keyword to this bug, and suggest
> > title and text for the tracker issue; or you may create a tracker issue
> > yourself, if you are able to do so. For more details, see this document:
> >    http://dev.w3.org/html5/decision-policy/decision-policy.html
> > 
> > Status: Did Not Understand Request
> > Change Description: no spec change
> > Rationale: I don't understand. What is the concrete use case where a script
> > would be doing anything with a kind=metadata track and not know what the
> > metadata is but yet would still be able to do something useful with it?
> 
> My understanding (Bob may wish to correct) is as follows:
> 
> Page origin O exposes video/audio from a 3rd party P, which contains/refers to
> a metadata track sourced by P or sourced by a 4th party M.
> 
> Page origin O provides JS for interpreting metadata tracks with media types M1,
> M2, or M3.
> 
> If Page author O is provided with content type information for the metadata
> track contained in response headers (or by other means if fetched via
> non-HTTP), then O's JS can select appropriate handling of metadata content
> exposed to JS via TextTrackCue.getCueAsSource().
> 
> This information could be exposed to JS via a new TextTrack.type IDL attribute.

To expand, 3rd party P adds three in-band tracks: IB1 - parental control
content advisories, IB2 - SCTE-35 segment descriptors for targeted advertising
and IB3 -EISS for interactive television. (In reply to comment #3)
> (In reply to comment #2)
> > EDITOR'S RESPONSE: This is an Editor's Response to your comment. If you are
> > satisfied with this response, please change the state of this bug to CLOSED. If
> > you have additional information and would like the editor to reconsider, please
> > reopen this bug. If you would like to escalate the issue to the full HTML
> > Working Group, please add the TrackerRequest keyword to this bug, and suggest
> > title and text for the tracker issue; or you may create a tracker issue
> > yourself, if you are able to do so. For more details, see this document:
> >    http://dev.w3.org/html5/decision-policy/decision-policy.html
> > 
> > Status: Did Not Understand Request
> > Change Description: no spec change
> > Rationale: I don't understand. What is the concrete use case where a script
> > would be doing anything with a kind=metadata track and not know what the
> > metadata is but yet would still be able to do something useful with it?
> 
> My understanding (Bob may wish to correct) is as follows:
> 
> Page origin O exposes video/audio from a 3rd party P, which contains/refers to
> a metadata track sourced by P or sourced by a 4th party M.
> 
> Page origin O provides JS for interpreting metadata tracks with media types M1,
> M2, or M3.
> 
> If Page author O is provided with content type information for the metadata
> track contained in response headers (or by other means if fetched via
> non-HTTP), then O's JS can select appropriate handling of metadata content
> exposed to JS via TextTrackCue.getCueAsSource().
> 
> This information could be exposed to JS via a new TextTrack.type IDL attribute.

To expand, consider 3rd party P adding three in-band signaling tracks: IB1 -
content advisories for parental control, IB2 - SCTE35 segment descriptors for
targeted advertising and IB3 - EISS for interactive television. The user agent
executing Page O recognizes these in-band tracks and sources them as three
different track elements with kind = metadata as described in [1]. Since the
user agent knows how to recognize these in-band tracks it can inform JS of the
metadata type by a new TextTrack.type IDL attribute. Without this new
attribute, JS will have to contain logic to infer the metadata type, redoing
what the UA has already done.

[1] http://dev.w3.org/html5/spec/Overview.html#sourcing-in-band-text-tracks

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Received on Friday, 19 August 2011 22:18:07 GMT

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