[FFmpeg-devel] [PATCH] Use LCG to generate random data for dither instead of CPU-intesive LFG.

[Michael Niedermayer]

On Mon, Apr 25, 2011 at 09:27:54PM +0200, Reimar Döffinger wrote:
> On Mon, Apr 25, 2011 at 09:13:17PM +0200, Michael Niedermayer wrote:
> > On Mon, Apr 25, 2011 at 08:42:21PM +0200, Reimar Döffinger wrote:
> > > I am not able to hear any difference.
> > > Differences in FATE tests:
> > > AC3:
> > > stddev:    4.91 PSNR: 82.50 MAXDIFF:   55 bytes:   804864/   804864
> > > stddev:    0.28 PSNR:107.16 MAXDIFF:    2 bytes:  1032192/  1032192
> > > 
> > > EAC3:
> > > stddev:   20.26 PSNR: 70.20 MAXDIFF: 1054 bytes:   884736/   884736
> > > stddev:   13.27 PSNR: 73.87 MAXDIFF:  215 bytes:  2998272/  2998272
> > > stddev:    5.93 PSNR: 80.87 MAXDIFF:  100 bytes:   804864/   804864
> > > (no difference in fourth test)
> > > ---
> > >  libavcodec/ac3dec.c  |    9 +++++----
> > >  libavcodec/ac3dec.h  |    2 +-
> > >  libavcodec/eac3dec.c |    6 ++++--
> > >  3 files changed, 10 insertions(+), 7 deletions(-)
> > 
> > ok, i dont understand why an LFG was used to begin with
> > i also assume you didnt pick the numbers randomly but used standard
> > constants
> 
> Not sure about the initial value, but the others are from lfg.h

The initial value is irrelevant for this use case

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Frequently ignored awnser#1 FFmpeg bugs should be sent to our bugtracker. User
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