237 lines
7.6 KiB
C
237 lines
7.6 KiB
C
/*
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* iLBC - a library for the iLBC codec
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*
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* doCPLC.c - The iLBC low bit rate speech codec.
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*
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* Adapted by Steve Underwood <steveu@coppice.org> from the reference
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* iLBC code supplied in RFC3951.
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*
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* Original code Copyright (C) The Internet Society (2004).
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* All changes to produce this version Copyright (C) 2008 by Steve Underwood
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* All Rights Reserved.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*
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* $Id: doCPLC.c,v 1.2 2008/03/06 12:27:38 steveu Exp $
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*/
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/*! \file */
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <inttypes.h>
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#include <math.h>
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#include <string.h>
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#include "ilbc.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(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;
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float ftmp2;
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float 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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ftmp1 = 0.0f;
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ftmp2 = 0.0f;
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ftmp3 = 0.0f;
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for (i = 0; i < sRange; i++)
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{
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ftmp1 += buffer[bLen - sRange + i]*buffer[bLen - sRange + i - lag];
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ftmp2 += buffer[bLen - sRange + i - lag]*buffer[bLen - sRange + i - lag];
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ftmp3 += buffer[bLen - sRange + i]*buffer[bLen - sRange + i];
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}
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if (ftmp2 > 0.0f)
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{
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*cc = ftmp1*ftmp1/ftmp2;
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*gc = fabsf(ftmp1/ftmp2);
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*pm = fabsf(ftmp1)/(sqrtf(ftmp2)*sqrtf(ftmp3));
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}
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else
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{
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*cc = 0.0f;
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*gc = 0.0f;
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*pm = 0.0f;
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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(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_decode_state_t *iLBCdec_inst) /* (i/o) decoder instance */
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{
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int lag = 20l;
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int randlag;
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float gain;
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float 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;
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int pick;
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int use_lag;
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float ftmp;
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float randvec[ILBC_BLOCK_LEN_MAX];
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float pitchfact;
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float energy;
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/* Packet Loss */
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if (PLI == 1)
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{
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iLBCdec_inst->consPLICount += 1;
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if (iLBCdec_inst->prevPLI != 1)
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{
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/* previous frame not lost, determine pitch pred. gain */
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/* Search around the previous lag to find the best pitch period */
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lag = inlag - 3;
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compCorr(&maxcc,
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&gain,
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&max_per,
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iLBCdec_inst->prevResidual,
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lag,
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iLBCdec_inst->blockl,
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60);
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for (i = inlag - 2; i <= inlag + 3; i++)
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{
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compCorr(&maxcc_comp,
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&gain_comp,
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&per,
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iLBCdec_inst->prevResidual,
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i,
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iLBCdec_inst->blockl,
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60);
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if (maxcc_comp>maxcc)
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{
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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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else
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{
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/* previous frame lost, use recorded lag and periodicity */
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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 = 1.0f;
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if (iLBCdec_inst->consPLICount*iLBCdec_inst->blockl > 320)
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use_gain = 0.9f;
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else if (iLBCdec_inst->consPLICount*iLBCdec_inst->blockl > 2*320)
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use_gain = 0.7f;
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else if (iLBCdec_inst->consPLICount*iLBCdec_inst->blockl > 3*320)
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use_gain = 0.5f;
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else if (iLBCdec_inst->consPLICount*iLBCdec_inst->blockl > 4*320)
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use_gain = 0.0f;
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/* mix noise and pitch repeatition */
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ftmp = sqrtf(max_per);
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if (ftmp > 0.7f)
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pitchfact = 1.0f;
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else if (ftmp > 0.4f)
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pitchfact = (ftmp - 0.4f)/(0.7f - 0.4f);
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else
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pitchfact = 0.0f;
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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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/* compute concealed residual */
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energy = 0.0f;
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for (i = 0; i < iLBCdec_inst->blockl; i++)
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{
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/* noise component */
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iLBCdec_inst->seed = (iLBCdec_inst->seed*69069L + 1) & (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] = iLBCdec_inst->prevResidual[iLBCdec_inst->blockl + pick];
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else
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randvec[i] = randvec[pick];
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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] = iLBCdec_inst->prevResidual[iLBCdec_inst->blockl + pick];
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else
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PLCresidual[i] = PLCresidual[pick];
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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*PLCresidual[i] + (1.0f - pitchfact) * randvec[i]);
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else if (i < 160)
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PLCresidual[i] = 0.95f*use_gain*(pitchfact*PLCresidual[i] + (1.0f - pitchfact) * randvec[i]);
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else
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PLCresidual[i] = 0.9f*use_gain*(pitchfact*PLCresidual[i] + (1.0f - 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) < 30.0f)
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{
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gain = 0.0f;
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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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/* use old LPC */
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memcpy(PLClpc, iLBCdec_inst->prevLpc, (ILBC_LPC_FILTERORDER + 1)*sizeof(float));
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}
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else
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{
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/* no packet loss, copy input */
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memcpy(PLCresidual, decresidual, iLBCdec_inst->blockl*sizeof(float));
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memcpy(PLClpc, lpc, (ILBC_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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{
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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, (ILBC_LPC_FILTERORDER + 1)*sizeof(float));
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memcpy(iLBCdec_inst->prevResidual, PLCresidual, iLBCdec_inst->blockl*sizeof(float));
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}
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