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

Re: [media] change proposals for issue-152

From: Eric Carlson <eric.carlson@apple.com>
Date: Thu, 31 Mar 2011 07:49:03 -0700
Cc: Ian Hickson <ian@hixie.ch>, Mark Watson <watsonm@netflix.com>, "public-html-a11y@w3.org" <public-html-a11y@w3.org>
Message-id: <ABA56F78-509A-47B4-95A5-6AB85487E35F@apple.com>
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>

On Mar 30, 2011, at 9:22 PM, Silvia Pfeiffer wrote:

>  But I am told, UAs render them simply over each other
> at the top left corner. In any case, there will be a default rendering
> IIUC.
> 
  This is not quite right. Every visual track in MPEG-4 and QuickTime containers, at least, has a display matrix that determines where it is rendered. The movie's display box is the union of all visual track display boxes, eg. the size and position of a visual track affects the size of its movie.

  It is certainly *possible* to render an in-band track in the top left corner, and that may be the default in some media authoring software, but it is not a requirement.

eric
Received on Thursday, 31 March 2011 14:49:34 UTC

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