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

From: <bugzilla@jessica.w3.org>
Date: Sat, 13 Nov 2010 04:52:18 +0000
To: public-html-bugzilla@w3.org
Message-Id: <E1PH866-0001WR-Hh@jessica.w3.org>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=10642

--- Comment #69 from Silvia Pfeiffer <silviapfeiffer1@gmail.com> 2010-11-13 04:52:17 UTC ---
(In reply to comment #68)
> (In reply to comment #66)
> > Agree with David; IMO the poster is only an interstitial element at best.
> > Accessibility for the video element is best done through subtitling, linked
> > transcripts, etc.
> 
> Sorry Frank, but must disagree.
> 
> Given the fact that the author can specify *any* image as a poster frame image,
> it becomes content in-and-of-itself: there is no mandate or technical means to
> ensure that the image used is a frame from the video, or that it even directly
> relates to the video. 
> 
> It may be *presumed* that this would be the normal way that authors would use a
> poster frame image (http://www.w3.org/Bugs/Public/show_bug.cgi?id=10642#c22),
> but there is no practical or programmatic means of ensuring this: consider a
> Film Festival site, where each film's "poster" would be a branding exercise for
> the Festival and have nothing to do with the film itself - the image might even
> include (yech) text... the point is, we have no idea *what* kind of image will
> be used here, and further have no way of 'policing' how a poster image will be
> used.
> 
> As such, the image used as the poster frame requires a means of directly
> linking the 'alternative text' for that image to the image.
> 
> Silvia Pfeiffer suggested:
> > All that would be required is an extra sentence to encourage users to
> > explain the poster content as part of the alternative text of the video
> > element. (http://www.w3.org/Bugs/Public/show_bug.cgi?id=10642#c62)
> 
> Once again, this presumes that the image is directly related to the video, a
> presumption we should not be making.


It is specified through a @src attribute on a <video> element and shown as a
replacement for the video before the video starts playing back. I think your
assumption that it may have nothing to do with the video only holds true when
that image is not used in the @src attribute, but otherwise it has a very
strong link to it. Even in your example: once the user clicks on the play
button, the image is removed and replaced by the video and therefore they are
strongly linked to each other.

However, my argument is not that we do not need a text alternative for the
poster. I do argue that we need that. But I also argue that when we have a text
replacement for the video, we can include the text replacement for the poster
in that piece of text - it does not have to be separate.

So, as an example: an alternative text for film festival videos may be:
"Video poster shows .....blah. Video is about .... blah."

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Received on Saturday, 13 November 2010 04:52:20 GMT

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