/******************************************************************
iLBC Speech Coder ANSI-C Source Code
doCPLC.c
Copyright (C) The Internet Society (2004).
All Rights Reserved.
******************************************************************/
#include <math.h>
#include <string.h>
#include <stdio.h>
#include "iLBC_define.h"
/*----------------------------------------------------------------*
* Compute cross correlation and pitch gain for pitch prediction
* of last subframe at given lag.
*---------------------------------------------------------------*/
void compCorr(
float *cc, /* (o) cross correlation coefficient */
float *gc, /* (o) gain */
float *pm,
float *buffer, /* (i) signal buffer */
int lag, /* (i) pitch lag */
int bLen, /* (i) length of buffer */
int sRange /* (i) correlation search length */
){
int i;
float ftmp1, ftmp2, ftmp3;
/* Guard against getting outside buffer */
if ((bLen-sRange-lag)<0) {
sRange=bLen-lag;
}
ftmp1 = 0.0;
ftmp2 = 0.0;
ftmp3 = 0.0;
for (i=0; i<sRange; i++) {
ftmp1 += buffer[bLen-sRange+i] *
buffer[bLen-sRange+i-lag];
ftmp2 += buffer[bLen-sRange+i-lag] *
buffer[bLen-sRange+i-lag];
ftmp3 += buffer[bLen-sRange+i] *
buffer[bLen-sRange+i];
}
if (ftmp2 > 0.0) {
*cc = ftmp1*ftmp1/ftmp2;
*gc = (float)fabs(ftmp1/ftmp2);
*pm=(float)fabs(ftmp1)/
((float)sqrt(ftmp2)*(float)sqrt(ftmp3));
}
else {
*cc = 0.0;
*gc = 0.0;
*pm=0.0;
}
}
/*----------------------------------------------------------------*
* Packet loss concealment routine. Conceals a residual signal
* and LP parameters. If no packet loss, update state.
*---------------------------------------------------------------*/
void doThePLC(
float *PLCresidual, /* (o) concealed residual */
float *PLClpc, /* (o) concealed LP parameters */
int PLI, /* (i) packet loss indicator
0 - no PL, 1 = PL */
float *decresidual, /* (i) decoded residual */
float *lpc, /* (i) decoded LPC (only used for no PL) */
int inlag, /* (i) pitch lag */
iLBC_Dec_Inst_t *iLBCdec_inst
/* (i/o) decoder instance */
){
int lag=20, randlag;
float gain, maxcc;
float use_gain;
float gain_comp, maxcc_comp, per, max_per=0;
int i, pick, use_lag;
float ftmp, randvec[BLOCKL_MAX], pitchfact, energy;
/* Packet Loss */
if (PLI == 1) {
iLBCdec_inst->consPLICount += 1;
/* if previous frame not lost,
determine pitch pred. gain */
if (iLBCdec_inst->prevPLI != 1) {
/* Search around the previous lag to find the
best pitch period */
lag=inlag-3;
compCorr(&maxcc, &gain, &max_per,
iLBCdec_inst->prevResidual,
lag, iLBCdec_inst->blockl, 60);
for (i=inlag-2;i<=inlag+3;i++) {
compCorr(&maxcc_comp, &gain_comp, &per,
iLBCdec_inst->prevResidual,
i, iLBCdec_inst->blockl, 60);
if (maxcc_comp>maxcc) {
maxcc=maxcc_comp;
gain=gain_comp;
lag=i;
max_per=per;
}
}
}
/* previous frame lost, use recorded lag and periodicity */
else {
lag=iLBCdec_inst->prevLag;
max_per=iLBCdec_inst->per;
}
/* downscaling */
use_gain=1.0;
if (iLBCdec_inst->consPLICount*iLBCdec_inst->blockl>320)
use_gain=(float)0.9;
else if (iLBCdec_inst->consPLICount*
iLBCdec_inst->blockl>2*320)
use_gain=(float)0.7;
else if (iLBCdec_inst->consPLICount*
iLBCdec_inst->blockl>3*320)
use_gain=(float)0.5;
else if (iLBCdec_inst->consPLICount*
iLBCdec_inst->blockl>4*320)
use_gain=(float)0.0;
/* mix noise and pitch repeatition */
ftmp=(float)sqrt(max_per);
if (ftmp>(float)0.7)
pitchfact=(float)1.0;
else if (ftmp>(float)0.4)
pitchfact=(ftmp-(float)0.4)/((float)0.7-(float)0.4);
else
pitchfact=0.0;
/* avoid repetition of same pitch cycle */
use_lag=lag;
if (lag<80) {
use_lag=2*lag;
}
/* compute concealed residual */
energy = 0.0;
for (i=0; i<iLBCdec_inst->blockl; i++) {
/* noise component */
iLBCdec_inst->seed=(iLBCdec_inst->seed*69069L+1) &
(0x80000000L-1);
randlag = 50 + ((signed long) iLBCdec_inst->seed)%70;
pick = i - randlag;
if (pick < 0) {
randvec[i] =
iLBCdec_inst->prevResidual[
iLBCdec_inst->blockl+pick];
} else {
randvec[i] = randvec[pick];
}
/* pitch repeatition component */
pick = i - use_lag;
if (pick < 0) {
PLCresidual[i] =
iLBCdec_inst->prevResidual[
iLBCdec_inst->blockl+pick];
} else {
PLCresidual[i] = PLCresidual[pick];
}
/* mix random and periodicity component */
if (i<80)
PLCresidual[i] = use_gain*(pitchfact *
PLCresidual[i] +
((float)1.0 - pitchfact) * randvec[i]);
else if (i<160)
PLCresidual[i] = (float)0.95*use_gain*(pitchfact *
PLCresidual[i] +
((float)1.0 - pitchfact) * randvec[i]);
else
PLCresidual[i] = (float)0.9*use_gain*(pitchfact *
PLCresidual[i] +
((float)1.0 - pitchfact) * randvec[i]);
energy += PLCresidual[i] * PLCresidual[i];
}
/* less than 30 dB, use only noise */
if (sqrt(energy/(float)iLBCdec_inst->blockl) < 30.0) {
gain=0.0;
for (i=0; i<iLBCdec_inst->blockl; i++) {
PLCresidual[i] = randvec[i];
}
}
/* use old LPC */
memcpy(PLClpc,iLBCdec_inst->prevLpc,
(LPC_FILTERORDER+1)*sizeof(float));
}
/* no packet loss, copy input */
else {
memcpy(PLCresidual, decresidual,
iLBCdec_inst->blockl*sizeof(float));
memcpy(PLClpc, lpc, (LPC_FILTERORDER+1)*sizeof(float));
iLBCdec_inst->consPLICount = 0;
}
/* update state */
if (PLI) {
iLBCdec_inst->prevLag = lag;
iLBCdec_inst->per=max_per;
}
iLBCdec_inst->prevPLI = PLI;
memcpy(iLBCdec_inst->prevLpc, PLClpc,
(LPC_FILTERORDER+1)*sizeof(float));
memcpy(iLBCdec_inst->prevResidual, PLCresidual,
iLBCdec_inst->blockl*sizeof(float));
}