[theora] Closed Captioning

Ralph Giles zen6669 at zen.co.uk
Wed Dec 4 17:27:25 PST 2002

On Wednesday, December 4, 2002, at 09:16  pm, Joe Straitiff wrote:

> The main difference between the US and European versions are that the
> european versions are all graphical (they do have sections talking 
> about
> character based encoding but it's so vague and up to implementation 
> that
> I've never seen anyone use it) and the US is fully character based.  
> So the
> DVB is similar to DVD's subtitling, i.e. they use a graphics rendering 
> model
> and push graphics through on their stream.

Vector or raster graphics?

We intend to use mng for raster overlays, which provides a superset of 
image-based subtitles. Of course character based ones are more flexible 
and accessible for alternate uses, but there are enough cases where the 
control (or simplicity) of graphic overlays make them worthwhile.

Vector graphics become more attractive as the video resolution goes up, 
but I don't think it makes sense to try and codify something for 
theora. Have to leave something for v2.

> Hope this info helps ;)

It does, thanks.


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