[theora] Closed Captioning

[David Siebert]

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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>>
>
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