270 lines
7.6 KiB
C
270 lines
7.6 KiB
C
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/******************************************************************
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iLBC Speech Coder ANSI-C Source Code
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doCPLC.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 <math.h>
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#include <string.h>
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#include <stdio.h>
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#include "iLBC_define.h"
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/*----------------------------------------------------------------*
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* Compute cross correlation and pitch gain for pitch prediction
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* of last subframe at given lag.
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*---------------------------------------------------------------*/
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void compCorr(
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float *cc, /* (o) cross correlation coefficient */
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float *gc, /* (o) gain */
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float *pm,
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float *buffer, /* (i) signal buffer */
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int lag, /* (i) pitch lag */
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int bLen, /* (i) length of buffer */
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int sRange /* (i) correlation search length */
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){
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int i;
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float ftmp1, ftmp2, ftmp3;
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/* Guard against getting outside buffer */
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if ((bLen-sRange-lag)<0) {
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sRange=bLen-lag;
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}
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ftmp1 = 0.0;
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ftmp2 = 0.0;
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ftmp3 = 0.0;
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for (i=0; i<sRange; i++) {
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ftmp1 += buffer[bLen-sRange+i] *
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buffer[bLen-sRange+i-lag];
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ftmp2 += buffer[bLen-sRange+i-lag] *
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buffer[bLen-sRange+i-lag];
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ftmp3 += buffer[bLen-sRange+i] *
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buffer[bLen-sRange+i];
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}
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if (ftmp2 > 0.0) {
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*cc = ftmp1*ftmp1/ftmp2;
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*gc = (float)fabs(ftmp1/ftmp2);
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*pm=(float)fabs(ftmp1)/
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((float)sqrt(ftmp2)*(float)sqrt(ftmp3));
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}
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else {
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*cc = 0.0;
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*gc = 0.0;
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*pm=0.0;
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}
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}
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/*----------------------------------------------------------------*
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* Packet loss concealment routine. Conceals a residual signal
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* and LP parameters. If no packet loss, update state.
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*---------------------------------------------------------------*/
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void doThePLC(
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float *PLCresidual, /* (o) concealed residual */
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float *PLClpc, /* (o) concealed LP parameters */
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int PLI, /* (i) packet loss indicator
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0 - no PL, 1 = PL */
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float *decresidual, /* (i) decoded residual */
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float *lpc, /* (i) decoded LPC (only used for no PL) */
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int inlag, /* (i) pitch lag */
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iLBC_Dec_Inst_t *iLBCdec_inst
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/* (i/o) decoder instance */
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){
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int lag=20, randlag;
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float gain, maxcc;
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float use_gain;
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float gain_comp, maxcc_comp, per, max_per=0;
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int i, pick, use_lag;
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float ftmp, randvec[BLOCKL_MAX], pitchfact, energy;
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/* Packet Loss */
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if (PLI == 1) {
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iLBCdec_inst->consPLICount += 1;
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/* if previous frame not lost,
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determine pitch pred. gain */
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if (iLBCdec_inst->prevPLI != 1) {
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/* Search around the previous lag to find the
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best pitch period */
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lag=inlag-3;
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compCorr(&maxcc, &gain, &max_per,
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iLBCdec_inst->prevResidual,
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lag, iLBCdec_inst->blockl, 60);
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for (i=inlag-2;i<=inlag+3;i++) {
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compCorr(&maxcc_comp, &gain_comp, &per,
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iLBCdec_inst->prevResidual,
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i, iLBCdec_inst->blockl, 60);
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if (maxcc_comp>maxcc) {
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maxcc=maxcc_comp;
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gain=gain_comp;
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lag=i;
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max_per=per;
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}
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}
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}
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/* previous frame lost, use recorded lag and periodicity */
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else {
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lag=iLBCdec_inst->prevLag;
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max_per=iLBCdec_inst->per;
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}
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/* downscaling */
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use_gain=1.0;
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if (iLBCdec_inst->consPLICount*iLBCdec_inst->blockl>320)
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use_gain=(float)0.9;
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else if (iLBCdec_inst->consPLICount*
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iLBCdec_inst->blockl>2*320)
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use_gain=(float)0.7;
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else if (iLBCdec_inst->consPLICount*
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iLBCdec_inst->blockl>3*320)
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use_gain=(float)0.5;
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else if (iLBCdec_inst->consPLICount*
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iLBCdec_inst->blockl>4*320)
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use_gain=(float)0.0;
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/* mix noise and pitch repeatition */
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ftmp=(float)sqrt(max_per);
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if (ftmp>(float)0.7)
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pitchfact=(float)1.0;
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else if (ftmp>(float)0.4)
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pitchfact=(ftmp-(float)0.4)/((float)0.7-(float)0.4);
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else
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pitchfact=0.0;
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/* avoid repetition of same pitch cycle */
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use_lag=lag;
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if (lag<80) {
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use_lag=2*lag;
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}
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/* compute concealed residual */
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energy = 0.0;
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for (i=0; i<iLBCdec_inst->blockl; i++) {
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/* noise component */
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iLBCdec_inst->seed=(iLBCdec_inst->seed*69069L+1) &
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(0x80000000L-1);
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randlag = 50 + ((signed long) iLBCdec_inst->seed)%70;
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pick = i - randlag;
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if (pick < 0) {
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randvec[i] =
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iLBCdec_inst->prevResidual[
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iLBCdec_inst->blockl+pick];
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} else {
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randvec[i] = randvec[pick];
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}
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/* pitch repeatition component */
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pick = i - use_lag;
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if (pick < 0) {
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PLCresidual[i] =
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iLBCdec_inst->prevResidual[
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iLBCdec_inst->blockl+pick];
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} else {
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PLCresidual[i] = PLCresidual[pick];
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}
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/* mix random and periodicity component */
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if (i<80)
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PLCresidual[i] = use_gain*(pitchfact *
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PLCresidual[i] +
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((float)1.0 - pitchfact) * randvec[i]);
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else if (i<160)
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PLCresidual[i] = (float)0.95*use_gain*(pitchfact *
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PLCresidual[i] +
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((float)1.0 - pitchfact) * randvec[i]);
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else
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PLCresidual[i] = (float)0.9*use_gain*(pitchfact *
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PLCresidual[i] +
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((float)1.0 - pitchfact) * randvec[i]);
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energy += PLCresidual[i] * PLCresidual[i];
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}
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/* less than 30 dB, use only noise */
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if (sqrt(energy/(float)iLBCdec_inst->blockl) < 30.0) {
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gain=0.0;
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for (i=0; i<iLBCdec_inst->blockl; i++) {
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PLCresidual[i] = randvec[i];
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}
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}
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/* use old LPC */
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memcpy(PLClpc,iLBCdec_inst->prevLpc,
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(LPC_FILTERORDER+1)*sizeof(float));
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}
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/* no packet loss, copy input */
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else {
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memcpy(PLCresidual, decresidual,
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iLBCdec_inst->blockl*sizeof(float));
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memcpy(PLClpc, lpc, (LPC_FILTERORDER+1)*sizeof(float));
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iLBCdec_inst->consPLICount = 0;
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}
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/* update state */
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if (PLI) {
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iLBCdec_inst->prevLag = lag;
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iLBCdec_inst->per=max_per;
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}
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iLBCdec_inst->prevPLI = PLI;
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memcpy(iLBCdec_inst->prevLpc, PLClpc,
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(LPC_FILTERORDER+1)*sizeof(float));
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memcpy(iLBCdec_inst->prevResidual, PLCresidual,
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iLBCdec_inst->blockl*sizeof(float));
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}
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