[media] discussion on how to render captions in HTML5

Hi media a11y folks, hi Eric,

In today's call we had a brief discussion on the WHATWG specification of
rendering of time-synchronized text with audio and video resources, see
http://www.whatwg.org/specs/web-apps/current-work/complete/rendering.html#timed-tracks-0.

The point I was making was that I am disappointed that for <audio> elements
there is no rendering. I was suggesting that for both, <audio> and <video>
elements, rendering of time-synchronized text should depend on the @controls
attribute of the <audio> and <video> elements. The reason behind this is
that I expect a menu to be made available to the user through the @controls
that allows the user to activate/deactivate text tracks from the list of
available text tracks. Because that list is made available through the
@controls, I would also expect that the rendering of the text cues depends
on this @controls attribute being available.

However, the specification says that <audio> elements don't render any
time-synchronized text, but only <video> elements do.

We didn't get very far in the discussion - in particular Eric had some
important points to make. Thus, I'd like to take up this discussion here
again.

Cheers,
Silvia.