114 lines
3.1 KiB
C
114 lines
3.1 KiB
C
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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) The Internet Society (2004).
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All Rights Reserved.
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******************************************************************/
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#include "iLBC_define.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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iLBC_Enc_Inst_t *iLBCenc_inst,
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/* (i/o) the encoder state structure */
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float *residual /* (i) lpc residual signal */
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) {
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float max_ssqEn, fssqEn[NSUB_MAX], bssqEn[NSUB_MAX], *pp;
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int n, l, max_ssqEn_n;
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const float ssqEn_win[NSUB_MAX-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_MAX*sizeof(float));
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memset(bssqEn, 0, NSUB_MAX*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<iLBCenc_inst->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=iLBCenc_inst->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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if (iLBCenc_inst->mode==20) l=1;
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else l=0;
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max_ssqEn=(fssqEn[0]+bssqEn[1])*ssqEn_win[l];
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max_ssqEn_n=1;
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for (n=2; n<iLBCenc_inst->nsub; n++) {
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l++;
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if ((fssqEn[n-1]+bssqEn[n])*ssqEn_win[l] > max_ssqEn) {
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max_ssqEn=(fssqEn[n-1]+bssqEn[n]) *
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ssqEn_win[l];
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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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