> 
> Hi 
> 
> I am a student doing a University project. I am trying to add MS
> stereo to the dist10 code so it will be useful if I know where the
> tonality index c(w) is called and saved. I am trying to use it for
> MS threshold calculations. Just a little curious about the
> psymodel.c functions L3psycho_anal_ns and L3psycho_anal. Counldn't
> really understand the psychoacoustics model 2 of dist10. In dist10,
> there is only one call for psycho analysis. What are the differences
> between these 2 function calls? They look quite similar to me
> especially the agruments that are being called from encoder.c. Will
> appreciate all help.
> 

One of the biggest differences between l3psycho_anal_ns and
l3psyco_anal is exactly what you are asking about - how the estimate
the tonality index.  One is a tweaked and cleaned up version of the
MPEG1/2 recommendation:  the predictiictability of the energy in each
band over several granules.  I believe it comes from thesis work
of one of the creators of MP3.  The other is based on how peaked the
spectrum is, and uses data just from a single granule.  Naoki wrote
it based on data in Zweicker's book.  

Keep in mind that all the models are very crude estimates,
and the output should be considered as a rough guide to the noise
shaping algorthims rather than absolute truth.  

Mark
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