/******************************************************************       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;   }