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Re: Liaison response - template on MIME type parameter for TimedText

From: David Singer <singer@apple.com>
Date: Mon, 12 May 2014 09:34:56 +0200
Cc: Cyril Concolato <cyril.concolato@telecom-paristech.fr>, TTWG <public-tt@w3.org>
Message-id: <7AF0E002-372A-4976-A226-56BA61BCBA07@apple.com>
To: Glenn Adams <glenn@skynav.com>

On May 11, 2014, at 20:30 , Glenn Adams <glenn@skynav.com> wrote:

> On Mon, May 5, 2014 at 5:42 AM, Cyril Concolato <cyril.concolato@telecom-paristech.fr> wrote:
> Hi all,
> Some points worth highlighting/repeating:
> - Aside from the MP4 problem, the problem is general. Consider a DASH MPD pointing to a TTML file (not packaged in a MP4). How can a player know that it'll be able to play it meaningfully without downloading the entire TTML file?
> TTML resources should have a declaration in either the root (<tt>) element start tag, in the form of a ttp:profile attribute, that specifies the processor profile required to process the document. 

You say singular “the”, but a document can be conformant with more than one profile, can’t it?  How do I indicate that?

> That is, I would prefer using the simple expression you specify above: codecs="stpp.ttml". Any further determination about processability should use the existing TTML profile mechanism described above.

The trouble is that this requires fetching the document.  In some environments (e.g. DASH) one wants to make a ‘can play’ determination based on the MIME type and its parameters.  Ideally, the MIME type and parameters are diagnostic.

David Singer
Manager, Software Standards, Apple Inc.
Received on Monday, 12 May 2014 07:35:27 UTC

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