Re: Support for advanced caption features (inc rollup)

On Tue, Dec 4, 2012 at 2:42 PM, Ian Hickson <ian@hixie.ch> wrote:

> On Tue, 4 Dec 2012, Anna Cavender wrote:
> > >
> > > The requirements are similar (though not even remotely identical, for
> > > example there's no way to drag and drop cues on a TV), but the
> > > constraints are vastly different (for example, live TV historically
> > > couldn't have a two-second delay loop and users care more about
> > > syncing captions to the picture than readable captions, but on the
> > > Internet a two-second delay is a non-issue even for live streams and
> > > so we can get readable captions and still get the sync right).
> >
> > A two-second delay will certainly be an issue for real-time interactive
> > communication.  Real-time captioning in these scenarios should be
> > displayed as soon as it is available and any delay will negatively
> > affect access to the conversation.  The idea of rendering regions seems
> > crucial here.
>
> Given that neither <video> nor WebVTT support real-time captioning, this
> is kind of moot in a discussion of WebVTT and <video>.
>
> If we wanted to support real-time captions of low-latency video we'd have
> to do far more than just put roll-up captions in WebVTT.
>
> (Note that instant messaging isn't "roll-up", by the way. It's line-at-a-
> time, and as a near non-stop user of this medium, I'm pretty confident in
> saying that that is fine.)
>

To clarify, I was proposing live captioning for video conferencing, not
instant messaging and not necessarily roll-up, as a use case for the
Region.  There exist proposals to use WebVTT in DASH [1] and HLS [2], so
this isn't too far fetched.  A Region would enable appending of cues as a
captioner types.

Indeed, much more would be required to support real-time captions in
WebVTT, but it is a potential use case for the Region.

[1] http://concolato.wp.mines-telecom.fr/category/general/mpeg/dash/
[2] http://tools.ietf.org/html/draft-pantos-http-live-streaming-09


>
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> Ian Hickson               U+1047E                )\._.,--....,'``.    fL
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