doCPLC.h File Reference

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Functions
void	doThePLC (float *PLCresidual, float *PLClpc, int PLI, float *decresidual, float *lpc, int inlag, iLBC_Dec_Inst_t *iLBCdec_inst)

Function Documentation

doThePLC()

void doThePLC	(	float *	PLCresidual,
		float *	PLClpc,
		int	PLI,
		float *	decresidual,
		float *	lpc,
		int	inlag,
		iLBC_Dec_Inst_t *	iLBCdec_inst
	)

Definition at line 79 of file doCPLC.c.

References iLBC_Dec_Inst_t_::blockl, BLOCKL_MAX, compCorr(), iLBC_Dec_Inst_t_::consPLICount, LPC_FILTERORDER, iLBC_Dec_Inst_t_::per, iLBC_Dec_Inst_t_::prevLag, iLBC_Dec_Inst_t_::prevLpc, iLBC_Dec_Inst_t_::prevPLI, iLBC_Dec_Inst_t_::prevResidual, and iLBC_Dec_Inst_t_::seed.

Referenced by iLBC_decode().

    {
       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));
   }