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@gel.usherb.ca --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/