Lines Matching defs:lpc
13 function: LPC low level routines
14 last mod: $Id: lpc.c 16227 2009-07-08 06:58:46Z xiphmont $
18 /* Some of these routines (autocorrelator, LPC coefficient estimator)
51 #include "lpc.h"
55 /* Autocorrelation LPC coeff generation algorithm invented by
59 Output: m lpc coefficients, excitation energy */
63 double *lpc=alloca(sizeof(*lpc)*(m));
76 /* Generate lpc coefficients from autocorr values */
86 memset(lpc+i,0,(m-i)*sizeof(*lpc));
95 for(j=0;j<i;j++)r-=lpc[j]*aut[i-j];
98 /* Update LPC coefficients and total error */
100 lpc[i]=r;
102 double tmp=lpc[j];
104 lpc[j]+=r*lpc[i-1-j];
105 lpc[i-1-j]+=r*tmp;
107 if(i&1)lpc[j]+=lpc[j]*r;
120 lpc[j]*=damp;
125 for(j=0;j<m;j++)lpci[j]=(float)lpc[j];
136 /* in: coeff[0...m-1] LPC coefficients
