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ISSUE-314 (Temporally active is not defined for regions): Temporally active is not defined for regions [TTML 1.0]

From: Timed Text Working Group Issue Tracker <sysbot+tracker@w3.org>
Date: Wed, 21 May 2014 13:17:34 +0000
Message-Id: <E1Wn6Ok-0004Qi-F9@stuart.w3.org>
To: public-tt@w3.org
ISSUE-314 (Temporally active is not defined for regions): Temporally active is not defined for regions [TTML 1.0]

http://www.w3.org/AudioVideo/TT/tracker/issues/314

Raised by: Nigel Megitt
On product: TTML 1.0

The process for constructing Intermediate Synchronic Documents [1] assumes it is clear when a region is temporally active however the definition of this concept is unclear.

In particular it appears from §9.1.2 [2] that regions that are not temporally active "must not produce any visible marks when presented on a visual medium." yet if tts:showBackground="always" then this is untrue. In SMIL 2 §5.3.3 under the definition of showBackground [3] the distinction is made between regions being active and having showBackground=always, i.e. they are distinct concepts.

A solution to this would be to amend the process for constructing Intermediate Synchronic Documents to include additionally non-active regions that have showBackground="true".

While making such a change we should consider if it is acceptable to prune any regions whose tts:opacity=0. 

[1] http://www.w3.org/TR/ttml1/#semantics-region-layout-step-1
[2] http://www.w3.org/TR/ttml1/#layout-vocabulary-region
[3] http://www.w3.org/TR/2005/REC-SMIL2-20051213/layout.html#q8
Received on Wednesday, 21 May 2014 13:17:35 UTC

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