[theora] Closed Captioning

[Dan Miller]

fyi all --

MPlayer (www.mplayerhq.hu) has very extensive CC support.  It might be worth finding out how they do it.

We looked into this about a year ago for a project and I recall there were a number of different standards, as this thread attests.

-dan

> -----Original Message-----
> From: David Siebert [mailto:dsiebert at eclipsecat.com]
> Sent: Thursday, December 05, 2002 9:22 AM
> To: theora at xiph.org
> Subject: Re: [theora] Closed Captioning
> 
> 
> Line 21 uses chars the font is left up to the encoder. 
> Compared to DVB 
> it seems much more compact. It is also less flexiable as far as 
> controling the display. I think it could be better for allowing text 
> searches of the video.
> Our customers in AU and the UK us teletex for the captioning.
> 
> Joe Straitiff wrote:
> 
> >If I remember correctly, DVB is all raster graphics.  They 
> define several
> >graphic formats (4bit, 8bit, full color) to save bandwidth, 
> and there is
> >certain amount of buffer memory built into the model so you 
> can pre-load the
> >images.
> >
> >Vector would be nice for higher res...
> >
> >-Joe
> >
> >  
> >
> >>-----Original Message-----
> >>From: owner-theora at xiph.org 
> [mailto:owner-theora at xiph.org]On Behalf Of
> >>Ralph Giles
> >>Sent: Wednesday, December 04, 2002 5:27 PM
> >>To: theora at xiph.org
> >>Subject: Re: [theora] Closed Captioning
> >>
> >>
> >>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.
> >>
> >>  -r
> >>
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