[Bug 23113] Deal with mode for TextTrackCues that are not VTTCues

https://www.w3.org/Bugs/Public/show_bug.cgi?id=23113

--- Comment #3 from Philip Jägenstedt <philipj@opera.com> ---
(In reply to Graham from comment #2)
> I think the mode='showing' approach is really a band-aid that helps but
> doesn't solve all the problems. So maybe the starting point here is to
> define some of the problems that I believe we need to solve:
> 
> Problem1: App needs to know whether the UA is already showing these captions
> by itself. Currently the app can set mode='showing' and not know the result
> in the UA.
> 
> Problem2: App needs to know whether the UA is capable of showing these
> captions if requested to turn them on. There is no way interrogate the UA
> capabilities in order to, say,allow for loading a captioning display library
> in advance. 

I don't think either of these problem will appear in current implementations,
since everyone who exposes VTTCue will also render it when mode=='showing'. If
we just avoid adding interfaces which some browsers will render and some won't,
then just looking at the interface will be enough.

> Problem3: App needs to know whether the platform supports native captioning
> in one type and and whether it is capable of and whether it does convert
> these to another format when presenting to JS. For example: A UA might be
> able to leverage the platform's native display of CEA-708 captions when the
> video is presented fullscreen but not in partial screen mode. Support for
> captioning in the partial screen mode might be done by converting captions
> to WebVTT or TTML cues in order to make use of the UA's native captioning
> ability.

The fullscreen API just makes a website occupy the full screen but is still
just rendering as usual, so it seems unlikely that the ability to render
captions would be affected by it. As for querying which kinds of captions are
supported, just looking for the existence of its cue interface seems
sufficient, so e.g. if window.TTMLCue exist then the browser knows how to parse
and render TTML.

-- 
You are receiving this mail because:
You are the QA Contact for the bug.

Received on Thursday, 12 September 2013 08:29:11 UTC