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Re: Is longdesc a good solution? (was: Acessibility of <audio> and <video>)

From: Henri Sivonen <hsivonen@iki.fi>
Date: Tue, 9 Sep 2008 12:36:59 +0300
Cc: Leif Halvard Silli <lhs@malform.no>, HTML WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>
Message-Id: <A4CA8F64-6DDE-451A-B2E6-D14CD4B56B3D@iki.fi>
To: Matt Morgan-May <mattmay@adobe.com>

On Sep 9, 2008, at 00:26, Matt Morgan-May wrote:

> On 9/8/08 1:22 AM, "Henri Sivonen" <hsivonen@iki.fi> wrote:
>> On Sep 7, 2008, at 22:31, Leif Halvard Silli wrote:
>>
>>> <video>: Would you propose the use of <object> instead of <video>
>>> when HTML fallback for videos is wanted as well?
>>
>> No. I would propose that users who don't see the video track play the
>> video and listen to the soundtrack. When the content provider makes  
>> an
>> additional effort for addressing the not seeing the video track case,
>> I'd suggest the effort be put into making an alternative audio
>> description sound track.
>
> Where's the opportunity cost assessment on this one, then?
>
> It is clearly less work to produce a text equivalent and associate  
> it, than
> to script, voice and associate a secondary audio description track.

You are right. Even though I suggested merely listening to the sound  
track in the common case, I went straight to the rather impractical  
high end with the more accessible suggestion.

How far-fetched is audio description authoring in your assessment?  
Does it even make sense to build browser support for it?

In any case, a full-text transcript (including annotations recounting  
significant visual happenings) does not belong in <object> fallback,  
which is what Leif asked me about, because a full-text transcript-- 
once written--is useful in general. In particular, it is useful in  
cases where it is *also* useful to make <object> render the media file  
(even if only for the audio for blind and low-vision users and only  
for the video for deaf or low-hearing users). The transcript should be  
available on the same page or on another page via a plain link.

> Which is partly why WCAG 2 Guideline 1.2 offers authors the
> choice of full-text transcript as an alternative, at level A.
>
> What you're proposing means that the fallback that's good enough for  
> WCAG
> would need to be done as a hack in HTML5, rather than a clean semantic
> association.

Would this
<video src=movie.ogg>Please upgrade to a browser that supports HTML5  
video.</video><p><a href=transcript.html>Annotated transcript</a></p>
be a "hack"?

Is a semantic association between the <video> element and the  
transcript necessary if the link is very near the video in the  
document reading order?

-- 
Henri Sivonen
hsivonen@iki.fi
http://hsivonen.iki.fi/
Received on Tuesday, 9 September 2008 09:37:53 UTC

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