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

From: Matt Morgan-May <mattmay@adobe.com>
Date: Tue, 09 Sep 2008 13:16:26 -0700
To: Henri Sivonen <hsivonen@iki.fi>
CC: Leif Halvard Silli <lhs@malform.no>, HTML WG <public-html@w3.org>, W3C WAI-XTECH <wai-xtech@w3.org>
Message-ID: <C4EC27AA.E207%mattmay@adobe.com>

On 9/9/08 2:36 AM, "Henri Sivonen" <hsivonen@iki.fi> wrote:
> How far-fetched is audio description authoring in your assessment?
> Does it even make sense to build browser support for it?

There is plenty of audio-described content. Much of it is educational
material, though every episode of the Simpsons, for example, is also
described. It's not by any means impossible to do; my point was that it is a
step above providing a simple transcript.

HTML5 should have support for secondary audio tracks in any event.
Multilingual programming is another viable use case.

> 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.

I agree with the need for transcripts to be usable by everyone, but the
mechanism needs to be cleaner than this.

> 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"?

Yes, I'd say that's definitely a hack. (I also think that returning to the
day of telling users their browser isn't good enough is a pretty big step
backward, especially when they could instead embed another object 99% of
them already have. But that's not an accessibility issue.)

> 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?

Yes. What if there are 2 or more videos within the document?

We're beyond telling screen readers to scrape around for data. That's what
they're reduced to doing when the format in question doesn't provide them
with the kind of linkage they're looking for--it's a repair technique. (see
also: D-links).

Another problem with this is that if users steal HTML code for videos from
one another (which is a common scenario), transcripts will invariably get
lost in the shuffle if they're outside the <video> element. There should be
a way for authors to link the two items together, within that element.

The aria-describedby attrib may seem like a potential solution, but
transcripts are different from descriptions. I think that captions,
transcripts and audio descriptions are all suitably different from one
another to make the case for all of them to have attributes on <video>, and
the same is true for transcripts on <audio>.

-
m
Received on Tuesday, 9 September 2008 20:17:22 GMT

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