[FFmpeg-devel] [PATCH] libx264 psyrd update V4

Loren Merritt lorenm
Thu Jan 22 22:22:44 CET 2009

On Thu, 22 Jan 2009, Marcus Blomenkamp wrote:

> Terms that i found questionable/explainable/replaceable:
> psyrd vs psyrdo?
> rate-distortion optimization == RD mode decision != RD mode refinement 
> (which the average user would assume because 'optimization' sounds 
> similar to 'refinement')?

RD == RDO == rate-distortion == rate-distortion optimization.
(Well, RD can be applied to nouns that aren't literally "optimization", 
such as "RD metric" or "RD score", but any use of "RD" is part of 
some instance of "RDO".)
We sometimes omit the "O", because an encoder doesn't do anything other 
than optimize, so it's kinda redundant to say that some particular 
option also controls optimization.
RD mode decision != RD mode refinement, but both are forms of RDO. The 
difference is in which decisions they optimize and which candidate 
solutions they consider.

--Loren Merritt

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