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Re: Video Poster image (was RE: DRAFT analysis of fallback mechanisms for embedded content ACTION-66)

From: Eric Carlson <eric.carlson@apple.com>
Date: Fri, 03 Dec 2010 14:06:42 -0800
Cc: 'Maciej Stachowiak' <mjs@apple.com>, 'Martin Kliehm' <martin.kliehm@namics.com>, 'Silvia Pfeiffer' <silviapfeiffer1@gmail.com>, 'HTML Accessibility Task Force' <public-html-a11y@w3.org>
Message-id: <894C8502-2668-4E6A-A89E-6848B435CC90@apple.com>
To: John Foliot <jfoliot@stanford.edu>
John -

On Dec 3, 2010, at 1:35 PM, John Foliot wrote:

> Maciej Stachowiak wrote:
>> Why is that better than including that text in the video summary?
>> It seems like the poster frame and your suggested label/summary text
>> both serve the same purpose - helping the user decide if they want to
>> play the video.
> This may not always be true.
>> They are auxiliary content. Describing the poster frame
>> seems like an overly literal-minded approach to equivalent content.
> I have repeatedly suggested (and offered as example) image files that
> would serve as poster frames that contain content that is not related to a
> video. This can be doubly problematic when the image contains text (a
> likely probability). It is for this reasons that the image requires the
> ability to have an alt value. I again urge all to review
> http://dev.w3.org/html5/alt-techniques/#replacement 
>> What is needed is a summary of the video that equally allows non-
>> sighted users to decide if they want to play it, just as the poster
>> frame (whether explicit or built-in) does for sighted users. 
> This presumes that the poster frame will always be chosen to elicit that
> call-to-action. I am trying to explain that this may not always be the
> case - that the image chosen by any given author could serve an
> alternative purpose (whether branding, informational, or other) that is
> conceptually unrelated to a specific video, but meets other author
> needs/goals.
> I agree that the video should have a summary, and even leave open the door
> that it could be explicit (@summary) or 'relative' (aria-describedby) -
> where here the Summary would appear as text on the page for both sighted
> and non-sighted users.
> However that summary does not serve as the @alt value for the image being
> used - it can't, as then you are mixing oranges and apples. My video is
> not about "Stanford University - this video is closed captioned" it is
> about (whatever it is about). I have no disagreement that the author
> *could* add this information into a summary, but I must also concede that
> they might not, or that the text example I am using here is an imperfect
> example

  What about a video that includes the "poster image" as the first frame? Inserting an image into a video file doesn't magically make it relevant to the rest of the content. In your case, the video still is not about "Stanford University - this video is closed captioned", that is just what the first frame says.

  From the user's perspective, the <video> element is exactly the same when the page loads whether the "poster image" is a separate file or the first frame of the video. Why do you think the two cases require different markup? How will this lead to a better user experience for anyone?

Received on Friday, 3 December 2010 22:07:16 UTC

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