[Bug 10693] Need a means for navigating between related timed tracks of media elements

http://www.w3.org/Bugs/Public/show_bug.cgi?id=10693

--- Comment #10 from Silvia Pfeiffer <silviapfeiffer1@gmail.com> 2011-03-02 12:16:29 UTC ---
(In reply to comment #8)
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> Status: Rejected
> Change Description: no spec change
> Rationale: 
> 
> This seems like a really esoteric feature, certainly not a "v1" feature (we
> could easily add this in a future revision of the language).


To blind people the need to navigate between different resolution levels on the
timeline of a audio/video resource is actually very fundamental. This is not a
request for a big change - just for an attribute on <track> to identify at what
hierarchy level this track is supposed to be interpreted in relation to the
other <track> elements, such that keyboard-driven track switching (typically
up/down arrow) knows which are the adjacent tracks.


> Having said that, I'm not actually sure it's worth addressing explicitly at
> all. In the example, the software seems to just have multiple chapter tracks
> a couple of implied ones for media and file selection (flash card vs CD), then
> the tracks in the currently selected media file, which, for the "Understanding
> Health" book in question seems to consist of four tracks named "level 1",
> "level 2", "level 3", and "pages", and finally a couple more implied tracks
> called "time" and "bookmarks". This is entirely handled already by <track
> kind=chapter label> in HTML as far as I can tell.

The bit that is not supported is the switching between the tracks in a
controlled manner. If we could safely assume that the hierarchical relationship
between the tracks can be given through their order in the HTMLMediaElement's
list of tracks, then a keyboard-driven track switching wouldn't need any
additional information. However, a track from in-band could logically be a
super-track to an externally specified one, so we can't do it in this way. A
simple additional attribute seems adequate.


> I think before adding this feature we would need to have much more compelling
> use cases and a much more concrete explanation of how it would improve
> accessibility relative to what we have today.

I guess implementation of the <track> element and the different kinds of tracks
is necessary first before we can show the limitations for keyboard-driven track
switching and navigation. In my opinion we can leave this bug open until such
time and get back to the discussion then.

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Received on Wednesday, 2 March 2011 12:16:32 UTC