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[Bug 10642] No alternative text description for video key frame (poster)

From: <bugzilla@jessica.w3.org>
Date: Tue, 12 Oct 2010 23:13:15 +0000
To: public-html-a11y@w3.org
Message-Id: <E1P5o1z-0001qk-8n@jessica.w3.org>

--- Comment #54 from Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no> 2010-10-12 23:13:13 UTC ---
(In reply to comment #53)

   [ snip ]
> I just wouldn't want to use @alt to mean the alt text for the poster, because
> that would confuse people.
   [ snip ]
> Thus, @posteralt seems to make the most sense.
   [ snip]
> So, probably this is better:
> <video src="video.ogv" poster="image.png" alt="Ian Hickson - editor of
>  HTML5 spec" aria-label="a video about HTML5" controls>
> </video>

Indeed. :-)  Because here you used @alt, and not @posteralt. Please note a
problem, though, in your code: ARIA enabled AT will not discern the @alt from
the @aria-label, it is all smashed into one string, from the user's point
oview. I therefore think @title could be just fine - in that example.

We disagree about how problematic @alt eventually would be - I belive close to
zero problems w.r.t. understanding its correctly. (Defining it properly, might
be more difficult, though ...) 

I agree that @posteralt makes some sense - when I look at it and read its name.
However, it would be interesting to hear from UA and AT vendors as well as ARIA
experts if it would not be an advantage to reuse @alt. At the very least I
discovered, when did some heavy ARIA testing the last month, that @alt is
supported - it doesn't matter which element you place it on, ARIA enabled ATs
will pick it up. "It just works."

> It has to be in parallel to
> whatever alt text we have for video and tightly linked to the poster itself,
> because that's the only thing that it describes.

Please note that @alt, when used on <img>, has a variety of meanings. I think,
likewise, one must pick what @alt for <video> means in the context. What, for
instance, if the frame of the video simply contains some info about the film,
or its title? If the title of the video has already been mentioned in the
preceding element, then why repeat it inside @alt?  But if the video poster is
an essential part of the content of the page/article/section, then @alt should
indeed describe the image.

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Received on Tuesday, 12 October 2010 23:13:20 UTC

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