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Re: Tech Discussions on the Multitrack Media (issue-152)

From: David Singer <singer@apple.com>
Date: Wed, 16 Feb 2011 15:33:18 +0800
Cc: Jonas Sicking <jonas@sicking.cc>, Mark Watson <watsonm@netflix.com>, Philip Jägenstedt <philipj@opera.com>, public-html <public-html@w3.org>
Message-Id: <B5EEA1FF-0844-491F-85C8-CF2F3366886C@apple.com>
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
I think we might be in agreement here, but I am not being clear.

On Feb 16, 2011, at 15:22 , Silvia Pfeiffer wrote:

>> b) and the timing does not need to change, but the audio description has, as part of its mix-down, the appropriate portions of the main audio, then make the video the primary source, and offer a <track> which has multiple sources, one or more of which are the plain audio, others are the audio description
> 
> That would require the author to pull the main video into two separate
> resources

no...I am not being clear.

<video src="just the video, madam" />
<track src="primary audio" />
<track src="audio description mixed with the right bits of primary audio" kind="audio-desc-of-video" />

> 
> In case of a mix-down audio description - which I regard as the 20%
> use case

Oh.  I think it's the 90% use case.  Usually there isn't enough quiet time in the primary audio to give the audio description.

>> c) and the timing needs to change; offer two or more sources, one or more of which have the normal audio and normal timing, and one or more of which have the audio description with the revised timing
> 
> The problem here is that not just the audio changes timing, but also
> the video.

again, I am being unclear

<video>
  <source src="the usual normal program, muxed audio and video" />
  <source src="a described program, with timing changes in it, muxed audio and video" kind="audio-desc-of-video" />
</video>

>> while it is technically true that the user-agent may be able to make all sorts of ingenious displays, it's not a great system design to assume that the UA and the user will have the time or skills to make the choices over lots of ingenious possibilities.
> 
> We do in fact have to discuss how the display of multiple videos would
> work. Would they be expected to be displayed as picture-in-picture?

I'd love to be able to give them display areas, and adjust the page as needed to suit.  That's why I originally thought of media queries; they can be used as needed to adjust the entire page layout, and also 'style' the tracks in the video.


David Singer
Multimedia and Software Standards, Apple Inc.
Received on Wednesday, 16 February 2011 07:34:28 GMT

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