305 lines
9.2 KiB
C
Executable File
305 lines
9.2 KiB
C
Executable File
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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) 2001,
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Global IP Sound AB.
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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 "iLBC_define.h"
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#include "doCPLC.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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static 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 *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;
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ftmp1 = 0.0;
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ftmp2 = 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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}
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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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}
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else {
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*cc = 0.0;
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*gc = 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 gain_comp, maxcc_comp;
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int i, pick, offset;
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float ftmp, ftmp1, randvec[BLOCKL], pitchfact;
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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, (*iLBCdec_inst).prevResidual,
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lag, BLOCKL, 60);
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for (i=inlag-2;i<=inlag+3;i++) {
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compCorr(&maxcc_comp, &gain_comp,
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(*iLBCdec_inst).prevResidual,
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i, 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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}
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}
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if (gain > 1.0) {
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gain = 1.0;
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}
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}
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/* previous frame lost, use recorded lag and gain */
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else {
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lag=(*iLBCdec_inst).prevLag;
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gain=(*iLBCdec_inst).prevGain;
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}
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/* Attenuate signal and scale down pitch pred gain if
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several frames lost consecutively */
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if ((*iLBCdec_inst).consPLICount > 1) {
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gain *= (float)0.9;
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}
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/* Compute mixing factor of picth repeatition and noise */
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if (gain > PLC_XT_MIX) {
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pitchfact = PLC_YT_MIX;
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} else if (gain < PLC_XB_MIX) {
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pitchfact = PLC_YB_MIX;
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} else {
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pitchfact = PLC_YB_MIX + (gain - PLC_XB_MIX) *
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(PLC_YT_MIX-PLC_YB_MIX)/(PLC_XT_MIX-PLC_XB_MIX);
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}
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/* compute concealed residual */
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(*iLBCdec_inst).energy = 0.0;
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for (i=0; i<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] = gain *
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(*iLBCdec_inst).prevResidual[BLOCKL+pick];
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} else {
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randvec[i] = gain * randvec[pick];
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}
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/* pitch repeatition component */
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pick = i - lag;
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if (pick < 0) {
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PLCresidual[i] = gain *
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(*iLBCdec_inst).prevResidual[BLOCKL+pick];
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} else {
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PLCresidual[i] = gain * PLCresidual[pick];
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}
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/* mix noise and pitch repeatition */
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PLCresidual[i] = (pitchfact * PLCresidual[i] +
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((float)1.0 - pitchfact) * randvec[i]);
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(*iLBCdec_inst).energy += PLCresidual[i] *
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PLCresidual[i];
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}
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/* less than 30 dB, use only noise */
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if (sqrt((*iLBCdec_inst).energy/(float)BLOCKL) < 30.0) {
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(*iLBCdec_inst).energy = 0.0;
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gain=0.0;
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for (i=0; i<BLOCKL; i++) {
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PLCresidual[i] = randvec[i];
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(*iLBCdec_inst).energy += PLCresidual[i] *
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PLCresidual[i];
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}
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}
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/* conceal LPC by bandwidth expansion of old LPC */
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ftmp=PLC_BWEXPAND;
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PLClpc[0]=(float)1.0;
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for (i=1; i<LPC_FILTERORDER+1; i++) {
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PLClpc[i] = ftmp * (*iLBCdec_inst).prevLpc[i];
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ftmp *= PLC_BWEXPAND;
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}
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}
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/* previous frame lost and this frame OK, mixing in
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with new frame */
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else if ((*iLBCdec_inst).prevPLI == 1) {
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lag = (*iLBCdec_inst).prevLag;
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gain = (*iLBCdec_inst).prevGain;
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/* if pitch pred gain high, do overlap-add */
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if (gain >= PLC_GAINTHRESHOLD) {
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/* Compute mixing factor of pitch repeatition
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and noise */
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if (gain > PLC_XT_MIX) {
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pitchfact = PLC_YT_MIX;
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} else if (gain < PLC_XB_MIX) {
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pitchfact = PLC_YB_MIX;
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} else {
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pitchfact = PLC_YB_MIX + (gain - PLC_XB_MIX) *
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(PLC_YT_MIX-PLC_YB_MIX)/(PLC_XT_MIX-PLC_XB_MIX);
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}
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/* compute concealed residual for 3 subframes */
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for (i=0; i<3*SUBL; i++) {
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(*iLBCdec_inst).seed=((*iLBCdec_inst).seed*
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69069L+1) & (0x80000000L-1);
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randlag = 50 + ((signed long)
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(*iLBCdec_inst).seed)%70;
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/* noise component */
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pick = i - randlag;
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if (pick < 0) {
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randvec[i] = gain *
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(*iLBCdec_inst).prevResidual[BLOCKL+pick];
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} else {
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randvec[i] = gain * randvec[pick];
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}
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/* pitch repeatition component */
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pick = i - lag;
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if (pick < 0) {
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PLCresidual[i] = gain *
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(*iLBCdec_inst).prevResidual[BLOCKL+pick];
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} else {
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PLCresidual[i] = gain * PLCresidual[pick];
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}
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/* mix noise and pitch repeatition */
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PLCresidual[i] = (pitchfact * PLCresidual[i] +
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((float)1.0 - pitchfact) * randvec[i]);
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}
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/* interpolate concealed residual with actual
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residual */
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offset = 3*SUBL;
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for (i=0; i<offset; i++) {
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ftmp1 = (float) (i+1) / (float) (offset+1);
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ftmp = (float)1.0 - ftmp1;
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PLCresidual[i]=PLCresidual[i]*ftmp+
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decresidual[i]*ftmp1;
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}
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memcpy(PLCresidual+offset, decresidual+offset,
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(BLOCKL-offset)*sizeof(float));
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} else {
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memcpy(PLCresidual, decresidual, BLOCKL*sizeof(float));
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}
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/* copy LPC */
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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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/* no packet loss, copy input */
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else {
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memcpy(PLCresidual, decresidual, BLOCKL*sizeof(float));
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memcpy(PLClpc, lpc, (LPC_FILTERORDER+1)*sizeof(float));
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}
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/* update state */
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(*iLBCdec_inst).prevLag = lag;
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(*iLBCdec_inst).prevGain = gain;
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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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BLOCKL*sizeof(float));
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}
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