[whatwg] Thoughts on video accessibility

Dave Singer singer at apple.com
Tue Dec 9 20:56:08 PST 2008

At 21:33  +1300 9/12/08, Robert O'Callahan wrote:
>For what it's worth, loading an intermediate document of some new 
>type which references other streams to be loaded adds a lot of 
>complexity to the browser implementation. It creates new states that 
>the decoder can be in, and introduces new failure modes. It creates 
>new timing issues and possibly new security issues.

I'm not sure I agree;  but if you believe that, we should address it 
no matter which way this discussion goes.  It should absolutely be 
possible to reference a SMIL file, or an MP4 or MOV file with 
external data (to give only two examples) from a <video> or <audio> 
element, and have the DOM, events, states, and APis work correctly.

Also, I should say that we quite deliberately left off associating 
and synchronizing media from our initial proposal for the media 
elements, for two reasons:
a) we believe that SMIL files should be embeddable;
b) it's an easy line to draw;  you want media integration, use a 
media integration language such as SMIL.  If you start adding some 
integration, it's very hard to know where to stop.

As for user or user-agent supplied subtitles etc., that can (of 
course) be a UA feature or option.  If a unique content ID would help 
find such subtitle files, then I am hoping that the media annotations 
group would come up with a workable scheme (something the music 
industry is still, ahem, struggling with).
David Singer
Multimedia Standards, Apple Inc.

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