W3C home > Mailing lists > Public > public-html-a11y@w3.org > April 2011

Re: text track associations

From: David Singer <singer@apple.com>
Date: Fri, 08 Apr 2011 11:06:07 -0700
Cc: Silvia Pfeiffer <silviapfeiffer1@gmail.com>, Mark Watson <watsonm@netflix.com>, Eric Carlson <eric.carlson@apple.com>, Ian Hickson <ian@hixie.ch>, "public-html-a11y@w3.org" <public-html-a11y@w3.org>
Message-id: <81553E98-3C5B-4F75-A8B1-050DE4C7D7F3@apple.com>
To: Sean Hayes <Sean.Hayes@microsoft.com>

On Apr 8, 2011, at 2:16 , Sean Hayes wrote:

> In a multitrack API, since caption tracks are essentially the audio for Deaf and HoH use, we will need some way for these to follow the selected audio asset.
> If I have a presentation, with the option of switching to different a different audio resource (e.g director commentary which is longer, starts before and ends after the main movie). The captions for it need to be timed to the commentary audio, and so if it's in a markup element, live in that element. If the user has captions turned on and wants the commentary audio, then the captions for the commentary soundtrack will need to replace the captions for the original audio track, and render into the rectangle allotted for the main video.
> I'm not seeing how I would create this. 

I think that the optional additions and alternatives that are logically part of one resource need to share a timeline.  We mustn't forget we're in a web environment where we can use web markup to offer choices to the user.  It's common and expected that there is a 'top-level choice' -- do you want
a) the plain movie
b) the movie with director's commentary in parallel and inserted (longer)
c) the movie with audio description of video (longer, includes places where the video is paused to give time for the description)

I think we'll go crazy if the time-map of the optional/alternative parts is not common with the base resource.

David Singer
Multimedia and Software Standards, Apple Inc.
Received on Friday, 8 April 2011 18:06:35 UTC

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