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Re: Acessibility of <audio> and <video>

From: Smylers <Smylers@stripey.com>
Date: Wed, 3 Sep 2008 00:11:19 +0100
To: public-html@w3.org
Message-ID: <20080902231119.GA32419@stripey.com>

Leif Halvard Silli writes:

> Smylers 2008-09-02 16.58:
> 
> > 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 
> 
> There is difference beween using <video> and video.

Ah.  I'd presumed that <video> is intended to cope with all desires for
embedding videos in webpages; are there some situations in which <video>
is inappropriate and a different HTML 5 element should be used?

> > 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 
> 
> Take the flash example in LiveDom.validator.nu.

I couldn't trivially work out how to see it.  Any chance you could link
to it directly or provide the HTML one needs to type in the box to make
it display?  Thanks.

> > -- they all seem to be in the category of being 'important content'
> > on the page --
> 
> Important content = 'critical content' = alt text unavailable?

Yes critical content, in the sense that it's critical to the purpose of
the page -- and therefore particularly important (as with images) that a
good alternative representation be available, though not necessarily as
alt text.

> > so, as Lachlan suggests, alternative representations could be
> > embedded in the video and still be appropriate.
> 
> We know now, that alternative content can be added into graphica
> formats, including videos. However, we need to be able to do it in
> HTML as well.

Why?

> > 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 ... unnecessary for sighted viewers, and I'm not
> > sure it's reasonable to insist that authors should include this
> > duplication for accessibility reasons.
> 
> I, for one, did not argue that the content of @title should also 
> be repeatad in the mark-up, if that was what you meant.

Indeed; I was replying to a mail from Lachlan (but then neither did he
suggest text be duplicated, in both a title attribute _and_ visible on
the page).  However he did suggest that the best place to put
information which speaking browsers need in lieu of the poster image may
be somewhere visibly (I'm including title attributes in that, since
browsers can choose to display those in some circumstacnes) in the page
-- in content accessible to all, not just those who can't see the
poster.

I was attempting to come up with a scenario in which perhaps that
wouldn't be appropriate, and something akin to alt text for the poster
could be useful.

> if the poster frame was an <img> with a correctly used @alt, then
> there would be no repetion for sighted users, while there would also
> be a useful description of the poster for those with a browser which
> do not display pictures.

Yes; that was my point (well, not specifically that <img alt="..."> is
the best solution; there could be other mark-up that works as well).

> Btw, we should not suggest using the @title as if was some kind of
> @alt.

I don't think I was; I hadn't even considered a title attribute until
your mail mentioned it.  (Note when I said the "video's title", I meant
the real-world title of the video, what it's called; I wasn't referring
to a <video title="..."> attribute.)

> > 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.
> 
> Absolutely. This is what I am arguing.

I know -- that's why I wrote the above in reply to somebody who
disagreed with you!

Smylers
Received on Tuesday, 2 September 2008 23:11:57 GMT

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