[theora-dev] Keyframe seeking in Ogg and spec

Ralph Giles zen6669 at zen.co.uk
Mon Sep 16 14:31:44 PDT 2002

On Monday, Sep 16, 2002, at 22:03 Europe/London, Tabuleiro wrote:

> This might be a stupid question, and forgive me if it really is. But 
> if the
> codec is going to pickup information on the granulepos and multiply it 
> by
> the frame rate in order to find a reference time why don't we encode 
> the
> reference time directly in the granulepos, and save one step? This will
> allow variable frame rates if needed. Any reason why this is not a good
> solution?

There's nothing wrong with the specific idea and it may well make sense 
for some codecs. The reason monty doesn't want to do it that way is 
that in the specific case of vp3 it's more valuable to be able to use 
the information in the granulepos to identify keyframe.

Requiring that a codec be asked about the interpretation of the 
granulepos is just a reasonable tradeoff here. Having a uniform 
timestamp format doesn't really help multiplexing tools because 
different codecs still have different latency requirements and headers.


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