[theora-dev] question about ogg mapping

Ralph Giles giles at xiph.org
Thu Jun 12 02:43:53 PDT 2003

On Thursday, June 12, 2003, at 03:28 am, Dan Miller wrote:

> Question: is it permissible to put more than one frame packet into a 
> page?  At 30 fps, Ogg page overhead is on the order of 8 - 10 
> kbits/sec.  At low datarates, this is going to be unacceptable.

Yes that's fine. There wouldn't be any point to having pages if they 
weren't different from packets, and as you suggest, it's necessary to 
keep the overhead down.

> If I shove a few frames into a page, how does this affect the 
> granulepos stuff?

It's actually pages that have granulepos. The granulepos in the packet 
structure is just how they're passed to the ogg layer. Granulepos is 
'the total samples encoded after including all packets finished on this 
page', so libogg sets the page granulepos to the greatest granulepos of 
the packets that ended on that page.


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