[FFmpeg-devel] [PATCH] RealAudio 14.4K encoder

[Michael Niedermayer]

On Wed, Jun 02, 2010 at 01:13:17PM +0200, Francesco Lavra wrote:
> On Sun, 2010-05-23 at 20:52 +0200, Francesco Lavra wrote:
> [...]
> > Floating point, with orthogonalization, with gain quantization done the
> > fast way
> > stddev:  210.14 PSNR: 49.88 bytes:   200000/   200320
> > stddev:  202.50 PSNR: 50.20 bytes:   143680/   144000
> > stddev:  196.30 PSNR: 50.47 bytes:   744960/   745280
> > stddev:  786.06 PSNR: 38.42 bytes:  5370560/  5370880
> > stddev:  422.29 PSNR: 43.82 bytes:   814080/   814400
> > stddev:  495.53 PSNR: 42.43 bytes:   432320/   432640
> > stddev:  396.24 PSNR: 44.37 bytes:  1741120/  1741440
> > 
> > Floating point, with orthogonalization, with gain quantization done
> > taking into account the rounding error of the 5 best entries
> > stddev:  210.49 PSNR: 49.86 bytes:   200000/   200320
> > stddev:  201.69 PSNR: 50.24 bytes:   143680/   144000
> > stddev:  200.05 PSNR: 50.31 bytes:   744960/   745280
> > stddev:  786.22 PSNR: 38.42 bytes:  5370560/  5370880
> > stddev:  419.41 PSNR: 43.88 bytes:   814080/   814400
> > stddev:  497.65 PSNR: 42.39 bytes:   432320/   432640
> > stddev:  395.23 PSNR: 44.39 bytes:  1741120/  1741440
> > 
> > I'd say we should go for the fast gain qantization, and in attachment is
> > an cleaned up patch for it, with code duplication removed.
> > I still have to try the iterative method, will do that in a few days I
> > think.
> 
> I have implemented an algorithm with multiple iterations in the codebook
> search, and here are the results with 2 iterations:
> 
> Floating point, with orthogonalization, with gain quantization done the
> fast way, 2 iterations
> stddev:  212.22 PSNR: 49.79 bytes:   200000/   200320
> stddev:  213.08 PSNR: 49.76 bytes:   143680/   144000
> stddev:  210.23 PSNR: 49.88 bytes:   744960/   745280
> stddev:  768.60 PSNR: 38.62 bytes:  5370560/  5370880
> stddev:  402.07 PSNR: 44.24 bytes:   814080/   814400
> stddev:  501.12 PSNR: 42.33 bytes:   432320/   432640
> stddev:  390.40 PSNR: 44.50 bytes:  1741120/  1741440
> 
> As you can see, no sensible improvements are brought by this approach,
> and in some cases PSNR is even worse.
> In case you want to take a look a the code, it's attached: at each
> iteration, the vectors used to search a given codebook are
> orthogonalized with the previously found vectors from the other two
> codebooks.
> 

> So my proposal is to go for the simpler method, with no iterations, like
> in the attached (updated to latest svn) patch.

ok
btw, is the code stable enough to add a regresion test? or is it
giving different results between compilers/cpus?
a reg test would be usefull


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

While the State exists there can be no freedom; when there is freedom there
will be no State. -- Vladimir Lenin
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