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/******************************************************************
iLBC Speech Coder ANSI-C Source Code
FrameClassify.c
Copyright (C) The Internet Society (2004).
All Rights Reserved.
******************************************************************/
#include "iLBC_define.h"
/*---------------------------------------------------------------*
* Classification of subframes to localize start state
*--------------------------------------------------------------*/
int FrameClassify( /* index to the max-energy sub-frame */
iLBC_Enc_Inst_t *iLBCenc_inst,
/* (i/o) the encoder state structure */
float *residual /* (i) lpc residual signal */
) {
float max_ssqEn, fssqEn[NSUB_MAX], bssqEn[NSUB_MAX], *pp;
int n, l, max_ssqEn_n;
const float ssqEn_win[NSUB_MAX-1]={(float)0.8,(float)0.9,
(float)1.0,(float)0.9,(float)0.8};
const float sampEn_win[5]={(float)1.0/(float)6.0,
(float)2.0/(float)6.0, (float)3.0/(float)6.0,
(float)4.0/(float)6.0, (float)5.0/(float)6.0};
/* init the front and back energies to zero */
memset(fssqEn, 0, NSUB_MAX*sizeof(float));
memset(bssqEn, 0, NSUB_MAX*sizeof(float));
/* Calculate front of first seqence */
n=0;
pp=residual;
for (l=0; l<5; l++) {
fssqEn[n] += sampEn_win[l] * (*pp) * (*pp);
pp++;
}
for (l=5; l<SUBL; l++) {
fssqEn[n] += (*pp) * (*pp);
pp++;
}
/* Calculate front and back of all middle sequences */
for (n=1; n<iLBCenc_inst->nsub-1; n++) {
pp=residual+n*SUBL;
for (l=0; l<5; l++) {
fssqEn[n] += sampEn_win[l] * (*pp) * (*pp);
bssqEn[n] += (*pp) * (*pp);
pp++;
}
for (l=5; l<SUBL-5; l++) {
fssqEn[n] += (*pp) * (*pp);
bssqEn[n] += (*pp) * (*pp);
pp++;
}
for (l=SUBL-5; l<SUBL; l++) {
fssqEn[n] += (*pp) * (*pp);
bssqEn[n] += sampEn_win[SUBL-l-1] * (*pp) * (*pp);
pp++;
}
}
/* Calculate back of last seqence */
n=iLBCenc_inst->nsub-1;
pp=residual+n*SUBL;
for (l=0; l<SUBL-5; l++) {
bssqEn[n] += (*pp) * (*pp);
pp++;
}
for (l=SUBL-5; l<SUBL; l++) {
bssqEn[n] += sampEn_win[SUBL-l-1] * (*pp) * (*pp);
pp++;
}
/* find the index to the weighted 80 sample with
most energy */
if (iLBCenc_inst->mode==20) l=1;
else l=0;
max_ssqEn=(fssqEn[0]+bssqEn[1])*ssqEn_win[l];
max_ssqEn_n=1;
for (n=2; n<iLBCenc_inst->nsub; n++) {
l++;
if ((fssqEn[n-1]+bssqEn[n])*ssqEn_win[l] > max_ssqEn) {
max_ssqEn=(fssqEn[n-1]+bssqEn[n]) *
ssqEn_win[l];
max_ssqEn_n=n;
}
}
return max_ssqEn_n;
}
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