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Re: Acessibility of <audio> and <video>

From: Smylers <Smylers@stripey.com>
Date: Tue, 2 Sep 2008 15:58:32 +0100
To: public-html@w3.org
Message-ID: <20080902145832.GN2588@stripey.com>

Lachlan Hunt writes:

> Leif Halvard Silli wrote:
> 
> > Lachlan Hunt 2008-09-01 23.36:
> > 
> > > Unlike video, images have no way embedding accessibility features
> > > within them, and their meaning is very often depending on the
> > > context.
> >
> > Our recent debate about EXIF proves opposite.
>
> Although it can contain descriptions, that's not particularly useful
> when the alternate text needs to be context sensitive.

If people start wanting to use videos for logos, decoration, mere
illustration, text replacement, as icons, or whatever then they would
need <img>-like alt text -- and we'd have the same thing as with images,
where a single image could serve different purposes (and as such require
different alt text) on different pages.

But there doesn't seem to be a desire for such use of videos -- they all
seem to be in the category of being 'important content' on the page --
so, as Lachlan suggests, alternative representations could be embedded
in the video and still be appropriate.

> > Link: http://www.dagbladet.no/kultur/2008/09/01/545443.html
>
> That's just using the poster frame for its intended purpose: providing
> a visual, iconic representation of the video to indicate what the
> video is about.

If a page has several videos in it, the poster frames for each may be
chosen such that a sighted user can use them to distinguish them and
pick which video she wishes to watch.  It may be that no other content
is needed on the page for her to make such a decision.

However, somebody reliant on a speaking browser would not have that
information available.  Obviously such a person wouldn't be able to see
the videos either, but they may still wish to play them for their audio
tracks.

Each video's title, or other information which helps pick between them,
obviously _could_ be included in the HTML next to the video.  But this
may be of no benefit to sighted users.  Consider a page with videos of
speeches, with the poster frames containing head-shots of different
presidential candidates, each with a visible caption of their name and
party: putting their this information additionaly on the page with HTML
would be repeating it visually; that would be unnecessary for sighted
viewers, and I'm not sure it's reasonable to insist that authors should
include this duplication for accessibility reasons.

I'd've thought it better that there's some way in which non-image
alternative to the poster frame could be made available for speaking
browsers.

Smylers
Received on Tuesday, 2 September 2008 14:59:17 UTC

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