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ISSUE-308 (Related video object reference missing): It is unclear how a document is associated with a related video object [TTML IMSC 1.0]

From: Timed Text Working Group Issue Tracker <sysbot+tracker@w3.org>
Date: Fri, 02 May 2014 15:44:57 +0000
Message-Id: <E1WgFdx-0000R8-0p@shauna.w3.org>
To: public-tt@w3.org
ISSUE-308 (Related video object reference missing): It is unclear how a document is associated with a related video object [TTML IMSC 1.0]

http://www.w3.org/AudioVideo/TT/tracker/issues/308

Raised by: Nigel Megitt
On product: TTML IMSC 1.0

It is unclear in §4.3 [1] how the relationship between the document and the related video object can be established. 

[1] http://www.w3.org/TR/ttml-imsc1/#related-video-object

It would be helpful to state that the Related video object is the TTML1-defined Related media object.

If it is possible that the IMSC document is related to more than one video object, which appears possible, I don't understand how the frame rate constraints are applied. For example a content provider may create different video objects with the same IMSC document, perhaps to offer different size downloads by changing the frame rate (or pixel resolution). However §4.4 Synchronization appears to prevent this, requiring content providers to create a separate version of the IMSC document for each video version.

A solution to this is to use a more generic processing of times for synchronisation purposes.

If the IMSC profile does not support this use case then this needs to be made more explicit e.g. in §4.3.
Received on Friday, 2 May 2014 15:44:57 UTC

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