[whatwg] Thoughts on video accessibility

David Singer singer at apple.com
Thu Jul 16 06:56:52 PDT 2009

At 23:28  +1000 16/07/09, Silvia Pfeiffer wrote:
>  > 2) I think the environment can and should help select and configure type-1
>>  resources, where it can.  It shouldn't need to be always a manual step by
>>  the user interacting with the media player.  That is, I don't see why we
>>  cannot have the markup express "this source is better for people who have
>>  accessibility need X" (probably as a media query).  However, media queries
>>  are CSS, not HTML...
>Would you mind providing an example that demonstrates the use of media
>queries? I cannot currently imagine what that could look like and how
>it could work. Feels free to use CSS in addition to any require HTML
>(and javascript?). Since I cannot imagine what that would look like
>and how it could work, I cannot start to understand it as an

sure. using deliberately vague way of writing the media queries

<video blah blah ... >
    <source src="xx-O.ers" media="want-captions" />
    <source src="xx-N.ers" media="not want-captions" />

xx-O has open (burned in captions), uses the same codecs etc.  It 
gets selected if the user says they want captions, otherwise XX-N (no 
captions) is selected.

<video blah blah ... >
    <source src="xx-S.ers" media="want-sign-language" />
    <source src="xx.ers" />

xx-S has a sign-language overlay capability.  It gets selected for 
those users expressing a positive preference for sign language; 
otherwise we don't waste the bandwidth loading that, and we load the 
plain xx file.  It may be that the media part of the UA also detects 
this user preference and automatically enables sign language in xx-S.

Basically, I think we should have a framework which attempts to 
select and configure the appropriate source, so we get it right most 
of the time by default.

This (accessibility) is a subject that covers multiple groups, of course...
David Singer
Multimedia Standards, Apple Inc.

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