[whatwg] Introduction of media accessibility features

Silvia Pfeiffer silviapfeiffer1 at gmail.com
Fri Apr 9 15:41:29 PDT 2010

Hi all,

At the W3C there have been many discussions about how to introduce
accessibility for the media elements.

Over the last months, two proposals to improve the specification have
been developed within the media subgroup of the Accessibility Task

It is time to put them in front of a larger technical audience for
further discussion, improvement, and progress towards inclusion in the

Change Proposal 1:

This proposal introduces a JavaScript API for media resources that
have more than the usual main audio and video track. The idea is to
introduce a control mechanism for page authors to allow them to
activate / deactivate tracks for display. This is particularly
important since many media resources already contain caption and
subtitle tracks.

The proposal further has a further recommendation to include into the
UI control a menu to enable users to undertake the track activation /
deactivation interactively.

Change Proposal 2:

This proposal introduces declarative markup to associate external
timed text resources (such as captions and subtitles) with a media
resource. It introduces <track> and <trackgroup> elements to be used
inside media elements and provides some recommendations on how to
render the text resources.

Note that these change proposals are a first step towards resolving
media accessibility and will require further specifications.

For example, it is as yet unclear how the timed text fragments (also
called "text cues" or "text intervals") are to be rendered. Should
they be included in plain sight in the DOM? Should they be included in
a shadow DOM? Should they be rendered into an iframe-like construct?
And how would a Web Developer gain access to the text in a text
fragment - should there be a callback?

Any feedback, comments, suggestions welcome!


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