This Wiki page is edited by participants of the HTML Accessibility Task Force. It does not necessarily represent consensus and it may have incorrect information or information that is not supported by other Task Force participants, WAI, or W3C. It may also have some very useful information.
Media Chapters with Images
Text alternatives for video frames of chapters in Video
One request that has come up in discussions is that blind users would like to have the frames that come up from a navigation to cues in chapter tracks described by the screen reader.
We currently have the kind=metadata text tracks in HTML to experiment with such ideas.
Here's one idea for how it could be done.
Use a WebVTT file that describes the images, e.g.
WEBVTT 00:00:00.000 --> 00:00:10.700 <c.framedesc>Slide titled "HTML5 video accessibility and the WebVTT file format March 23rd 2011, Silvia Pfeifffer"</c> Title Slide 00:00:10.700 --> 00:00:47.600 <c.framedesc>Naomi Black stands in an auditorium at a podium</c> Introduction by Naomi Black 00:00:47.600 --> 00:01:50.100 <c.framedesc>Silvia Pfeiffer stands in an auditorium at a podium</c> Impact of Captions on the Web 00:01:50.100 --> 00:03:33.000 <c.framedesc>Slide titled "Requirements of a Web Text Format - captions/subtitles, text video descriptions, navigation/chapters metadata</c> Requirements of a Video text format 00:03:33.000 --> 00:04:57.766 <c.framedesc>Slide with a WebVTT file example</c> Simple WebVTT file 00:04:57.766 --> 00:06:16.666 <c.framedesc>Slide with a WebVTT formatted subtitles example file</c> Styled WebVTT file 00:06:16.666 --> 00:07:37.900 <c.framedesc>Slide with a WebVTT for internationalization i18n</c> Internationalized WebVTT file </nav>
The classes could be mapped to divs that could be provided as aria-describedby links on the chapter's name.
getCueAsHTML(0): <div id=framedesc0>Slide titled "HTML5 video accessibility and the WebVTT file format March 23rd 2011, Silvia Pfeifffer"</div> <p aria-describedby="framedesc0">Title Slide</p> </p>