102 lines
2.7 KiB
C
Executable File
102 lines
2.7 KiB
C
Executable File
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/******************************************************************
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iLBC Speech Coder ANSI-C Source Code
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FrameClassify.c
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Copyright (c) 2001,
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Global IP Sound AB.
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All rights reserved.
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******************************************************************/
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#include "iLBC_define.h"
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#include "FrameClassify.h"
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/*----------------------------------------------------------------*
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* Classification of subframes to localize start state
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*---------------------------------------------------------------*/
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int FrameClassify( /* index to the max-energy sub frame */
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float *residual /* (i) lpc residual signal */
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){
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float max_ssqEn, fssqEn[NSUB], bssqEn[NSUB], *pp;
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int n, l, max_ssqEn_n;
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const float ssqEn_win[NSUB-1]={(float)0.8,(float)0.9,
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(float)1.0,(float)0.9,(float)0.8};
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const float sampEn_win[5]={(float)1.0/(float)6.0,
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(float)2.0/(float)6.0, (float)3.0/(float)6.0,
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(float)4.0/(float)6.0, (float)5.0/(float)6.0};
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/* init the front and back energies to zero */
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memset(fssqEn, 0, NSUB*sizeof(float));
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memset(bssqEn, 0, NSUB*sizeof(float));
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/* Calculate front of first seqence */
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n=0;
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pp=residual;
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for(l=0;l<5;l++){
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fssqEn[n] += sampEn_win[l] * (*pp) * (*pp);
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pp++;
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}
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for(l=5;l<SUBL;l++){
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fssqEn[n] += (*pp) * (*pp);
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pp++;
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}
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/* Calculate front and back of all middle sequences */
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for(n=1;n<NSUB-1;n++) {
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pp=residual+n*SUBL;
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for(l=0;l<5;l++){
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fssqEn[n] += sampEn_win[l] * (*pp) * (*pp);
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bssqEn[n] += (*pp) * (*pp);
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pp++;
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}
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for(l=5;l<SUBL-5;l++){
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fssqEn[n] += (*pp) * (*pp);
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bssqEn[n] += (*pp) * (*pp);
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pp++;
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}
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for(l=SUBL-5;l<SUBL;l++){
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fssqEn[n] += (*pp) * (*pp);
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bssqEn[n] += sampEn_win[SUBL-l-1] * (*pp) * (*pp);
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pp++;
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}
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}
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/* Calculate back of last seqence */
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n=NSUB-1;
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pp=residual+n*SUBL;
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for(l=0;l<SUBL-5;l++){
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bssqEn[n] += (*pp) * (*pp);
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pp++;
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}
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for(l=SUBL-5;l<SUBL;l++){
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bssqEn[n] += sampEn_win[SUBL-l-1] * (*pp) * (*pp);
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pp++;
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}
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/* find the index to the weighted 80 sample with
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most energy */
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max_ssqEn=(fssqEn[0]+bssqEn[1])*ssqEn_win[0];
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max_ssqEn_n=1;
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for (n=2;n<NSUB;n++) {
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if ((fssqEn[n-1]+bssqEn[n])*ssqEn_win[n-1] > max_ssqEn) {
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max_ssqEn=(fssqEn[n-1]+bssqEn[n]) *
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ssqEn_win[n-1];
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max_ssqEn_n=n;
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}
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}
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return max_ssqEn_n;
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}
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