[FFmpeg-devel] [RFC] AAC Encoder, now more optimal

Michael Niedermayer michaelni
Sun Sep 7 01:11:18 CEST 2008

On Sat, Sep 06, 2008 at 08:15:55PM +0300, Kostya wrote:
> On Sat, Sep 06, 2008 at 06:17:38PM +0200, Michael Niedermayer wrote:
> > On Sat, Sep 06, 2008 at 06:36:16PM +0300, Kostya wrote:
> [choosing codebooks for coeffients encoding]
> > > IMO it should encode losslessly at this stage, so no rate distortion.
> > 
> > How much quality do we loose from this?
> none (yet) - 

You apparently misunderstood me, i meant 
how much quality is lost by ignoring distortion when choosing
codebooks? Though this doesnt matter if you fix it and make it use full RD
i just thought you wont from your first coment above. But judging from
your next comment below it seem you do plan to fix this so its all fine
and iam somewhat confused now :)

> quantization is performed the same way for all codebooks
> I still have to introduce codebook-specific quantization (and distortion from it).

It would be great if you did this before wasting more time with
approximating it, because the exact solution may very well be faster than
your approximation. pow() and cbrt() are rather slow and there is no need
to search through the codebook bruteforce, but id like you to implement the
bruteforce variant so we can verify that the optimized code does work

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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