- From: Benjamin Hawkes-Lewis <bhawkeslewis@googlemail.com>
- Date: Mon, 10 Aug 2009 07:53:09 +0100
On 10/08/2009 04:05, Remco wrote: > A title is a short description, and could be the movie title in the > case of a video element. WCAG 2 1.1.1 requires that: "If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content." "title" and "aria-labelledby" seem sufficient for this purpose. So do "figure" and "legend": http://dev.w3.org/html5/spec/Overview.html#the-figure-element > An alt is a textual alternative for the content. [snip] > For video, audio, object, iframe, this is a little sparse. [snip] > But Elephants Dream may not be a good example for a video where an alt > text would be useful. It's simply too complicated to replace with > alternative text. But if you have a short video that explains > something on Wikipedia, it would be tremendously helpful if the alt > text would convey the same meaning. A video of a ball falling to show > what gravity is, could have the alt text: "A ball accelerates as it > moves down. Next to the ball's trajectory, a speedometer increases > with 9.8 m/s per second.". If you want to provide an "alternative for time-based media" (in WCAG 2's phrase), then you want a method that can scale to contain semantic information, such as indicating language changes ("lang") or changes of speaker ("dialog"). Here's how WCAG 2 defines "alternative for time-based media": "document including correctly sequenced text descriptions of time-based visual and auditory information and providing a means for achieving the outcomes of any time-based interaction "Note: A screenplay used to create the synchronized media content would meet this definition only if it was corrected to accurately represent the final synchronized media after editing." http://www.w3.org/TR/WCAG20/#alt-time-based-mediadef Here's just three ways you could do this without changing HTML5, assuming the incorporation of WAI-ARIA: 1. <figure><legend>Ball acceleraton.<details>A ball accelerates as it moves down. Next to the ball's trajectory, a speedometer increases with 9.8 m/s per second.</details></legend><video>...</video></figure> 2. <video title="Ball acceleration" aria-describedby="alternative"...</video><p id="alternative">A ball accelerates as it moves down. Next to the ball's trajectory, a speedometer increases with 9.8 m/s per second.</p> 3. <video title="Interview with Barack Obama" aria-describedby="transcript-link"...</video><a href="transcript.html" id="transcript-link">Transcript of Interview with Barack Obama</a> See also: "WAI CG Consensus Resolutions on Text alternatives in HTML 5" (proposal for using "aria-describedby" in place of "longdesc"): http://www.w3.org/2009/06/Text-Alternatives-in-HTML5 WCAG 2 Technique "G159: Providing an alternative for time-based media for video-only content": http://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/G159 WCAG 2 Technique G58: Placing a link to the alternative for time-based media immediately next to the non-text content" http://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/G58.html Do these features meet your requirements? If not, why not? -- Benjamin Hawkes-Lewis
Received on Sunday, 9 August 2009 23:53:09 UTC