[Theora-dev] Re: Questions, MMX and co.
Adam D. Moss
adam at gimp.org
Thu Aug 26 00:42:52 PDT 2004
Ralph Giles wrote:
>>5) How to *validate* the implementation? It is probably easy to introduce
>>biais in the encoder in the C to MMX transformation process. On the other
>>hand, sometimes output is different and this is normal (psavgb does (A+B+1)/2
>>which is more precise than (A+B)/2). Maybe we can simply trust experimental
>>work, or rely on a good 4), but then...?
> Well, encoder output should be bit-for-bit identical, at least for the
> reference implementation. On the decoder one can make speed/quality
Is this the right way around? I thought the DEcoder had to be
bit-for-bit identical because that's what VP3 assumes (precise
decoding rules allow unbound GOP size, because of supposedly no
The MMXized ENcoder as it stands is certainly far from bit-for-bit
identical with the output of the reference encoder -- even its own
output between runs is non-deterministic (which probably isn't a good sign).
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