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Re: Survey ready on Media Multitrack API proposal

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Thu, 4 Mar 2010 07:40:12 +1100
Message-ID: <2c0e02831003031240g30abeb77m81d13cf97a5a2b5a@mail.gmail.com>
To: Eric Carlson <eric.carlson@apple.com>
Cc: Maciej Stachowiak <mjs@apple.com>, "Michael(tm) Smith" <mike@w3.org>, HTML Accessibility Task Force <public-html-a11y@w3.org>
On Thu, Mar 4, 2010 at 3:33 AM, Eric Carlson <eric.carlson@apple.com> wrote:
> On Mar 2, 2010, at 11:14 PM, Silvia Pfeiffer wrote:
>>> You also didn't answer my second question -  are track names typically
>>> unique? Do media container formats generally guarantee the presence of
>>> unique track names?
>> There is no guarantee of their existence - same for the role
>> attribute. But where they exist, they are unique.
>  Track IDs (which are numeric) in QuickTime and MPEG-4 files are guaranteed to be unique, track names are not required and are *not* guaranteed to be unique.

So maybe for MPEG the track ID is the one that should be mapped to the
this field here as text? Or alternatively it could be a combination of
track name and the track ID?

There is obviously work to be done still to map the information inside
the typically used container formats for HTML5 to this API.

For some background: The attributes have been chosen mostly to map
with the external captions spec also up for vote in another survey.
This will make for a uniform API across internal and external tracks.
The names have also been chosen to make sense in the HTML context and
be generic across file formats.

Received on Wednesday, 3 March 2010 20:41:05 UTC

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