[Bug 25261] Don't require TextTrack.kind = 'metadata' for DataCues?

https://www.w3.org/Bugs/Public/show_bug.cgi?id=25261

--- Comment #9 from Glenn Adams <glenn@skynav.com> ---
(In reply to Silvia Pfeiffer from comment #8)
> (In reply to Philip Jägenstedt from comment #7)
> > (In reply to Silvia Pfeiffer from comment #4)
> > > (In reply to Philip Jägenstedt from comment #3)
> > > > Sorry Aaron, I should have worded that more carefully.
> > > > 
> > > > I don't think anything (normative) needs to be said about DataCue rendering,
> > > > because there is no default rendering algorithm that could apply.
> > > 
> > > When cues are of kind captions, subtitles, chapters or descriptions, some
> > > kind of rendering is expected, see
> > > http://www.w3.org/html/wg/drafts/html/master/embedded-content.html#attr-
> > > track-kind .
> > > 
> > > The only kind of cue that is not rendered is of metadata. For that reason,
> > > kind=metadata is appropriate for DataCues which are per definition not
> > > rendered.
> > > 
> > > If we allowed DataCue to be on a caption track, for example, we'd need to
> > > define a rendering algorithm - likely the content of the text attribute
> > > being rendered verbatim on screen. Is there a use case for that?
> > 
> > It's not a matter of use cases, it's that guard in the spec is incomplete:
> > 
> > var track = document.createElement('track');
> > track.kind = 'metadata';
> > track.mode = 'hidden';
> > track.track.addCue(new DataCue(0, 0, new ArrayBuffer());
> > track.setAttribute('kind', 'captions');
> > 
> > Throwing an exception on that last line would be very weird. Lacking a
> > (sane) way to ensure that a DataCue is never in a TextTrack with a kind
> > other than metadata, just allowing it seems much simpler.
> 
> OK, but we have to deal with the consequences, which means we have to define
> "rules for updating the text track rendering", seeing as now DataCue objects
> can become active and rendered.
> 
> We have the following options:
> 1. no automatic rendering by UA
> 2. rendering of content of .text as plain text
> 
> If we pick 2. (which could be useful for debugging, for example), then we
> would probably render it at the bottom of the video viewport, centered.
> 
> What do ppl prefer?

definitely #1 (no rendering, an otherwise ignored by UA)

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Received on Sunday, 27 April 2014 01:39:35 UTC