[vorbis-dev] psytune.c - question

[Jean-Marc Valin]

Hi,

Can anyone explain to me the following lines taken from psytune.c .
I'm new to perceptual coding and I don't understand what the LPC coefficients
have to do with the masking threshold.

        for(j=0;j<framesize/2;j++)floor[j]=todB(floor[j])+150;
        amp=_curve_to_lpc(floor,lpc,&floorlook,frameno);
        _lpc_to_curve(floor,lpc,sqrt(amp),&floorlook,"Ffloor",frameno);
        for(j=0;j<framesize/2;j++)floor[j]=fromdB(floor[j]-150);

Also, I don't know whether this would be useful, but I have started integrating
Vorbis building blocks (so far MDCT and psycho) in the Overflow project
(http://freespeech.sourceforge.net/overflow.html). This is a "visual language"
oriented fowards signal processing (screenshots at
http://freespeech.sourceforge.net/FreeSpeech/html/Overflow/screenshots.html). I
could allow to "play with the blocks" and visualizing results with
recompiling... just a thought...

        Jean-Marc


-- 
Jean-Marc Valin
Universite de Sherbrooke - Genie Electrique
valj01 at gel.usherb.ca

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