[theora-dev] VP3 IDCT

Michael Niedermayer michaelni at gmx.at
Thu Mar 6 11:35:27 PST 2003


On Thursday 06 March 2003 20:01, Dan Miller wrote:
> > From: Michael Niedermayer [mailto:michaelni at gmx.at]
> >
> > btw, does theora/vp3 have a maximum allowed keyframe (or
> > co-located non-skiped
> > non-intra macroblock) limit like mpeg* ? IMHO it should have
> > one, otherwise
> > different decoders with different IDCTs will drift too much
> > like u mentioned
> The DCT/IDCT in VP3 is 100% integer-based, so our philosophy is: you must
> duplicate it exactly.  Drift is not allowed.  Therefore maximum frames to a
that means that existing IDCT hardware cant be used :(
and neither existing software IDCTs :(
for the DCT it shouldnt be an issue though as there cant be any drift

> keyframe is unnecessary.  There are reasons one might not want keyframes at
> all (except at the beginning of course). --- >8 ----
i guess because keyframes are quite large and with limited bandwidth & low 
delay its a problem ...

--- >8 ----
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