W3C home > Mailing lists > Public > public-html-a11y@w3.org > May 2011

Re: [media] alt technologies for paused video (and using ARIA)

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Sun, 15 May 2011 13:05:37 +1000
Message-ID: <BANLkTim+UBBxdxOkt50MSo7wcKmiuh7bsA@mail.gmail.com>
To: John Foliot <jfoliot@stanford.edu>
Cc: Victor Tsaran <vtsaran@yahoo-inc.com>, HTML Accessibility Task Force <public-html-a11y@w3.org>, James Craig <jcraig@apple.com>, Michael Cooper <cooper@w3.org>, "E.J. Zufelt" <everett@zufelt.ca>
On Fri, May 13, 2011 at 5:04 PM, John Foliot <jfoliot@stanford.edu> wrote:
> Silvia Pfeiffer wrote:
>> Would it not be much more useful to have:
>> <video src=".." controls aria-label="Yahoo! Media Player showing blah
>> blah blah" [poster=".."]>
>> </video>
> How would this render on screen for those users who have a very slow
> connection and are browsing with images disabled, are using a text-only
> browser, or have images disabled to save on download costs?
> No other instances of aria-label display text on screen (in fact the ARIA
> spec states that it is inappropriate to do so), why should it here?

I have been considering this for the last few days. This is a valid
issue and one which I had to investigate to understand further.

I think you are right and text-only browsers do not display aria-label
text (though it could actually be a very interesting piece of
information to display, but that's just not how it currently works, so
let's not argue about that).

So, I have been wondering what happens in text-only browsers. In fact,
I think text-only browsers is a use case that we should treat
separately from everything else, because we have a special means of
dealing with such browsers (this differentiates video from img, btw).

Text-only browsers behave the same as legacy browsers that do not
support the video element: they expose the html content from inside
the video element to the user. Therefore, the solution to providing a
"text alternative" (I prefer calling it a "text replacement") for the
video element and poster attribute to text-only browsers does not need
a special attribute on the video element, because we can already put
anything that we want inside the video element.

Thus, I would mark up the Clockwork Orange example for text-only
browser as follows:

      <video poster="media/ClockworkOrangetrailer.jpg" controls>
         <source src="media/ClockworkOrangetrailer.mp4">
         <source src="media/ClockworkOrangetrailer.webm">
         <source src="media/ClockworkOrangetrailer.ogv">
         <div id="posteralt">
           The video placeholder image shows a movie poster with the text
           "Stanley Kubrick's A Clockwork Orange" with a man peering through
           the letter 'A' holding a knife. It also reads 'Being the adventures
           of a young man whose principle interests are rape, ultra-violence
           and Beethoven'.
           Download the video in one of three formats from:
             <li><a href="media/ClockworkOrangetrailer.mp4">MPEG-4</a></li>
             <li><a href="media/ClockworkOrangetrailer.webm">WebM</a></li>
             <li><a href="media/ClockworkOrangetrailer.ogv">Ogg Theroa</a></li>

I've tested this in lynx and it does indeed display the poster
description and the download links.

(NOTE that this example ONLY shows the markup for text-only browsers -
I have left out all markup for screenreaders.)

This now opens an interesting option for a different use case, namely
that of providing a long text alternative on the placeholder image: I
wonder if it would be possible to use @aria-describedby on the <video>
element to link to a thus "hidden" paragraph inside the <video>
element for a long image description that is otherwise not displayed
to users. We wouldn't need to do the off-page hack and the description
would be with the element, thus not being repeated again when browsing
elsewhere on the page.


Received on Sunday, 15 May 2011 03:06:25 UTC

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