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Philosophically, the accessibility of HTML 5
video is a beautiful thing.
There is no fall-back accessibility content; instead, it’s just a link to the video and, perhaps, a transcript:
Your browser is not video-enabled; <a href="movie.ogg">download the video</a> and <a href="movie.txt">transcript</a>.
There is no “alternate text” attribute. Instead, each video is expected to carry its own synchronised captions—not “burned onto” the video, but in some kind of time-stamped text file so the browser can access it and display it over the video for users who require it. As an added bonus, search engines would be able to access this information.
The reason is good. Many videos are hosted in one place (for example, YouTube, DailyMotion etc) and embedded in many other sites. It’s highly unlikely that people embedding those videos would copy accessibility information, so it’s better that the video creator bags it all up together.
But what format to use? Given that discussions about the best video codec at an impasse, discussions about accessibility formats are unlikely to advance. This is not a fault of those who specify the language; it’s a problem of codecs, patents and closed standards vs open standards. (Related: Video of open video codecs discussion at Mozilla, and Mozilla’s General Counsel on Theora patents.)
But the situation is urgent. Sasquatch-wrestlin’ John Foliot writes that in the USA the The Twenty-first Century Communications and Video Accessibility Act of 2009 was introduced last month, and if enacted, big video sites like YouTube
would need to provide captioning .
In an excellent post The most pressing Accessibility issue in HTML5 today? <video> (which I urge you to read), John describes how captioning, like video itself, can already be accomplished through plugins.
If HTML 5 video is going to catch on (and we all hope plugin-less video that can be manipulated with scripting, integrate with canvas and SVG will catch on), it needs to be able to compete with plugins, especially if The Twenty-first Century Communications and Video Accessibility Act of 2009 looks close to becoming law.
Meanwhile, Sylvia Pfeiffer is plugging away at adding captioning to HTML 5 video, and is looking for your feedback.