RFC 3951
Internet Low Bit Rate Codec (iLBC)
Pages: 194
Experimental
Experimental
Part 6 of 6 – Pages 152 to 194
A.33. iCBSearch.h
/****************************************************************** iLBC Speech Coder ANSI-C Source Code iCBSearch.h Copyright (C) The Internet Society (2004). All Rights Reserved. ******************************************************************/ #ifndef __iLBC_ICBSEARCH_H #define __iLBC_ICBSEARCH_H
void iCBSearch(
iLBC_Enc_Inst_t *iLBCenc_inst,
/* (i) the encoder state structure */
int *index, /* (o) Codebook indices */
int *gain_index,/* (o) Gain quantization indices */
float *intarget,/* (i) Target vector for encoding */
float *mem, /* (i) Buffer for codebook construction */
int lMem, /* (i) Length of buffer */
int lTarget, /* (i) Length of vector */
int nStages, /* (i) Number of codebook stages */
float *weightDenum, /* (i) weighting filter coefficients */
float *weightState, /* (i) weighting filter state */
int block /* (i) the sub-block number */
);
#endif
A.34. iCBSearch.c
/******************************************************************
iLBC Speech Coder ANSI-C Source Code
iCBSearch.c
Copyright (C) The Internet Society (2004).
All Rights Reserved.
******************************************************************/
#include <math.h>
#include <string.h>
#include "iLBC_define.h"
#include "gainquant.h"
#include "createCB.h"
#include "filter.h"
#include "constants.h"
/*----------------------------------------------------------------*
* Search routine for codebook encoding and gain quantization.
*---------------------------------------------------------------*/
void iCBSearch(
iLBC_Enc_Inst_t *iLBCenc_inst,
/* (i) the encoder state structure */
int *index, /* (o) Codebook indices */
int *gain_index,/* (o) Gain quantization indices */
float *intarget,/* (i) Target vector for encoding */
float *mem, /* (i) Buffer for codebook construction */
int lMem, /* (i) Length of buffer */
int lTarget, /* (i) Length of vector */
int nStages, /* (i) Number of codebook stages */
float *weightDenum, /* (i) weighting filter coefficients */
float *weightState, /* (i) weighting filter state */
int block /* (i) the sub-block number */
){
int i, j, icount, stage, best_index, range, counter;
float max_measure, gain, measure, crossDot, ftmp;
float gains[CB_NSTAGES];
float target[SUBL];
int base_index, sInd, eInd, base_size;
int sIndAug=0, eIndAug=0;
float buf[CB_MEML+SUBL+2*LPC_FILTERORDER];
float invenergy[CB_EXPAND*128], energy[CB_EXPAND*128];
float *pp, *ppi=0, *ppo=0, *ppe=0;
float cbvectors[CB_MEML];
float tene, cene, cvec[SUBL];
float aug_vec[SUBL];
memset(cvec,0,SUBL*sizeof(float));
/* Determine size of codebook sections */
base_size=lMem-lTarget+1;
if (lTarget==SUBL) {
base_size=lMem-lTarget+1+lTarget/2;
}
/* setup buffer for weighting */
memcpy(buf,weightState,sizeof(float)*LPC_FILTERORDER);
memcpy(buf+LPC_FILTERORDER,mem,lMem*sizeof(float));
memcpy(buf+LPC_FILTERORDER+lMem,intarget,lTarget*sizeof(float));
/* weighting */
AllPoleFilter(buf+LPC_FILTERORDER, weightDenum,
lMem+lTarget, LPC_FILTERORDER);
/* Construct the codebook and target needed */
memcpy(target, buf+LPC_FILTERORDER+lMem, lTarget*sizeof(float));
tene=0.0;
for (i=0; i<lTarget; i++) {
tene+=target[i]*target[i];
}
/* Prepare search over one more codebook section. This section
is created by filtering the original buffer with a filter. */
filteredCBvecs(cbvectors, buf+LPC_FILTERORDER, lMem);
/* The Main Loop over stages */
for (stage=0; stage<nStages; stage++) {
range = search_rangeTbl[block][stage];
/* initialize search measure */
max_measure = (float)-10000000.0;
gain = (float)0.0;
best_index = 0;
/* Compute cross dot product between the target
and the CB memory */
crossDot=0.0;
pp=buf+LPC_FILTERORDER+lMem-lTarget;
for (j=0; j<lTarget; j++) {
crossDot += target[j]*(*pp++);
}
if (stage==0) {
/* Calculate energy in the first block of
'lTarget' samples. */
ppe = energy;
ppi = buf+LPC_FILTERORDER+lMem-lTarget-1;
ppo = buf+LPC_FILTERORDER+lMem-1;
*ppe=0.0;
pp=buf+LPC_FILTERORDER+lMem-lTarget;
for (j=0; j<lTarget; j++) {
*ppe+=(*pp)*(*pp++);
}
if (*ppe>0.0) {
invenergy[0] = (float) 1.0 / (*ppe + EPS);
} else {
invenergy[0] = (float) 0.0;
}
ppe++;
measure=(float)-10000000.0;
if (crossDot > 0.0) {
measure = crossDot*crossDot*invenergy[0];
}
}
else {
measure = crossDot*crossDot*invenergy[0];
}
/* check if measure is better */
ftmp = crossDot*invenergy[0];
if ((measure>max_measure) && (fabs(ftmp)<CB_MAXGAIN)) {
best_index = 0;
max_measure = measure;
gain = ftmp;
}
/* loop over the main first codebook section,
full search */
for (icount=1; icount<range; icount++) {
/* calculate measure */
crossDot=0.0;
pp = buf+LPC_FILTERORDER+lMem-lTarget-icount;
for (j=0; j<lTarget; j++) {
crossDot += target[j]*(*pp++);
}
if (stage==0) {
*ppe++ = energy[icount-1] + (*ppi)*(*ppi) -
(*ppo)*(*ppo);
ppo--;
ppi--;
if (energy[icount]>0.0) {
invenergy[icount] =
(float)1.0/(energy[icount]+EPS);
} else {
invenergy[icount] = (float) 0.0;
}
measure=(float)-10000000.0;
if (crossDot > 0.0) {
measure = crossDot*crossDot*invenergy[icount];
}
}
else {
measure = crossDot*crossDot*invenergy[icount];
}
/* check if measure is better */
ftmp = crossDot*invenergy[icount];
if ((measure>max_measure) && (fabs(ftmp)<CB_MAXGAIN)) {
best_index = icount;
max_measure = measure;
gain = ftmp;
}
}
/* Loop over augmented part in the first codebook
* section, full search.
* The vectors are interpolated.
*/
if (lTarget==SUBL) {
/* Search for best possible cb vector and
compute the CB-vectors' energy. */
searchAugmentedCB(20, 39, stage, base_size-lTarget/2,
target, buf+LPC_FILTERORDER+lMem,
&max_measure, &best_index, &gain, energy,
invenergy);
}
/* set search range for following codebook sections */
base_index=best_index;
/* unrestricted search */
if (CB_RESRANGE == -1) {
sInd=0;
eInd=range-1;
sIndAug=20;
eIndAug=39;
}
/* restricted search around best index from first
codebook section */
else {
/* Initialize search indices */
sIndAug=0;
eIndAug=0;
sInd=base_index-CB_RESRANGE/2;
eInd=sInd+CB_RESRANGE;
if (lTarget==SUBL) {
if (sInd<0) {
sIndAug = 40 + sInd;
eIndAug = 39;
sInd=0;
} else if ( base_index < (base_size-20) ) {
if (eInd > range) {
sInd -= (eInd-range);
eInd = range;
}
} else { /* base_index >= (base_size-20) */
if (sInd < (base_size-20)) {
sIndAug = 20;
sInd = 0;
eInd = 0;
eIndAug = 19 + CB_RESRANGE;
if(eIndAug > 39) {
eInd = eIndAug-39;
eIndAug = 39;
}
} else {
sIndAug = 20 + sInd - (base_size-20);
eIndAug = 39;
sInd = 0;
eInd = CB_RESRANGE - (eIndAug-sIndAug+1);
}
}
} else { /* lTarget = 22 or 23 */
if (sInd < 0) {
eInd -= sInd;
sInd = 0;
}
if(eInd > range) {
sInd -= (eInd - range);
eInd = range;
}
}
}
/* search of higher codebook section */
/* index search range */
counter = sInd;
sInd += base_size;
eInd += base_size;
if (stage==0) {
ppe = energy+base_size;
*ppe=0.0;
pp=cbvectors+lMem-lTarget;
for (j=0; j<lTarget; j++) {
*ppe+=(*pp)*(*pp++);
}
ppi = cbvectors + lMem - 1 - lTarget;
ppo = cbvectors + lMem - 1;
for (j=0; j<(range-1); j++) {
*(ppe+1) = *ppe + (*ppi)*(*ppi) - (*ppo)*(*ppo);
ppo--;
ppi--;
ppe++;
}
}
/* loop over search range */
for (icount=sInd; icount<eInd; icount++) {
/* calculate measure */
crossDot=0.0;
pp=cbvectors + lMem - (counter++) - lTarget;
for (j=0;j<lTarget;j++) {
crossDot += target[j]*(*pp++);
}
if (energy[icount]>0.0) {
invenergy[icount] =(float)1.0/(energy[icount]+EPS);
} else {
invenergy[icount] =(float)0.0;
}
if (stage==0) {
measure=(float)-10000000.0;
if (crossDot > 0.0) {
measure = crossDot*crossDot*
invenergy[icount];
}
}
else {
measure = crossDot*crossDot*invenergy[icount];
}
/* check if measure is better */
ftmp = crossDot*invenergy[icount];
if ((measure>max_measure) && (fabs(ftmp)<CB_MAXGAIN)) {
best_index = icount;
max_measure = measure;
gain = ftmp;
}
}
/* Search the augmented CB inside the limited range. */
if ((lTarget==SUBL)&&(sIndAug!=0)) {
searchAugmentedCB(sIndAug, eIndAug, stage,
2*base_size-20, target, cbvectors+lMem,
&max_measure, &best_index, &gain, energy,
invenergy);
}
/* record best index */
index[stage] = best_index;
/* gain quantization */
if (stage==0){
if (gain<0.0){
gain = 0.0;
}
if (gain>CB_MAXGAIN) {
gain = (float)CB_MAXGAIN;
}
gain = gainquant(gain, 1.0, 32, &gain_index[stage]);
}
else {
if (stage==1) {
gain = gainquant(gain, (float)fabs(gains[stage-1]),
16, &gain_index[stage]);
} else {
gain = gainquant(gain, (float)fabs(gains[stage-1]),
8, &gain_index[stage]);
}
}
/* Extract the best (according to measure)
codebook vector */
if (lTarget==(STATE_LEN-iLBCenc_inst->state_short_len)) {
if (index[stage]<base_size) {
pp=buf+LPC_FILTERORDER+lMem-lTarget-index[stage];
} else {
pp=cbvectors+lMem-lTarget-
index[stage]+base_size;
}
} else {
if (index[stage]<base_size) {
if (index[stage]<(base_size-20)) {
pp=buf+LPC_FILTERORDER+lMem-
lTarget-index[stage];
} else {
createAugmentedVec(index[stage]-base_size+40,
buf+LPC_FILTERORDER+lMem,aug_vec);
pp=aug_vec;
}
} else {
int filterno, position;
filterno=index[stage]/base_size;
position=index[stage]-filterno*base_size;
if (position<(base_size-20)) {
pp=cbvectors+filterno*lMem-lTarget-
index[stage]+filterno*base_size;
} else {
createAugmentedVec(
index[stage]-(filterno+1)*base_size+40,
cbvectors+filterno*lMem,aug_vec);
pp=aug_vec;
}
}
}
/* Subtract the best codebook vector, according
to measure, from the target vector */
for (j=0;j<lTarget;j++) {
cvec[j] += gain*(*pp);
target[j] -= gain*(*pp++);
}
/* record quantized gain */
gains[stage]=gain;
}/* end of Main Loop. for (stage=0;... */
/* Gain adjustment for energy matching */
cene=0.0;
for (i=0; i<lTarget; i++) {
cene+=cvec[i]*cvec[i];
}
j=gain_index[0];
for (i=gain_index[0]; i<32; i++) {
ftmp=cene*gain_sq5Tbl[i]*gain_sq5Tbl[i];
if ((ftmp<(tene*gains[0]*gains[0])) &&
(gain_sq5Tbl[j]<(2.0*gains[0]))) {
j=i;
}
}
gain_index[0]=j;
}
A.35. LPCdecode.h
/****************************************************************** iLBC Speech Coder ANSI-C Source Code LPC_decode.h Copyright (C) The Internet Society (2004). All Rights Reserved. ******************************************************************/ #ifndef __iLBC_LPC_DECODE_H #define __iLBC_LPC_DECODE_H void LSFinterpolate2a_dec( float *a, /* (o) lpc coefficients for a sub-frame */ float *lsf1, /* (i) first lsf coefficient vector */ float *lsf2, /* (i) second lsf coefficient vector */ float coef, /* (i) interpolation weight */ int length /* (i) length of lsf vectors */ ); void SimplelsfDEQ( float *lsfdeq, /* (o) dequantized lsf coefficients */ int *index, /* (i) quantization index */ int lpc_n /* (i) number of LPCs */ ); void DecoderInterpolateLSF( float *syntdenum, /* (o) synthesis filter coefficients */ float *weightdenum, /* (o) weighting denumerator coefficients */ float *lsfdeq, /* (i) dequantized lsf coefficients */ int length, /* (i) length of lsf coefficient vector */ iLBC_Dec_Inst_t *iLBCdec_inst /* (i) the decoder state structure */ ); #endif
A.36. LPCdecode.c
/****************************************************************** iLBC Speech Coder ANSI-C Source Code LPC_decode.c Copyright (C) The Internet Society (2004). All Rights Reserved. ******************************************************************/ #include <math.h> #include <string.h> #include "helpfun.h" #include "lsf.h" #include "iLBC_define.h" #include "constants.h" /*---------------------------------------------------------------* * interpolation of lsf coefficients for the decoder *--------------------------------------------------------------*/ void LSFinterpolate2a_dec( float *a, /* (o) lpc coefficients for a sub-frame */ float *lsf1, /* (i) first lsf coefficient vector */ float *lsf2, /* (i) second lsf coefficient vector */ float coef, /* (i) interpolation weight */ int length /* (i) length of lsf vectors */ ){ float lsftmp[LPC_FILTERORDER]; interpolate(lsftmp, lsf1, lsf2, coef, length); lsf2a(a, lsftmp); } /*---------------------------------------------------------------* * obtain dequantized lsf coefficients from quantization index *--------------------------------------------------------------*/ void SimplelsfDEQ( float *lsfdeq, /* (o) dequantized lsf coefficients */ int *index, /* (i) quantization index */ int lpc_n /* (i) number of LPCs */ ){ int i, j, pos, cb_pos;
/* decode first LSF */
pos = 0;
cb_pos = 0;
for (i = 0; i < LSF_NSPLIT; i++) {
for (j = 0; j < dim_lsfCbTbl[i]; j++) {
lsfdeq[pos + j] = lsfCbTbl[cb_pos +
(long)(index[i])*dim_lsfCbTbl[i] + j];
}
pos += dim_lsfCbTbl[i];
cb_pos += size_lsfCbTbl[i]*dim_lsfCbTbl[i];
}
if (lpc_n>1) {
/* decode last LSF */
pos = 0;
cb_pos = 0;
for (i = 0; i < LSF_NSPLIT; i++) {
for (j = 0; j < dim_lsfCbTbl[i]; j++) {
lsfdeq[LPC_FILTERORDER + pos + j] =
lsfCbTbl[cb_pos +
(long)(index[LSF_NSPLIT + i])*
dim_lsfCbTbl[i] + j];
}
pos += dim_lsfCbTbl[i];
cb_pos += size_lsfCbTbl[i]*dim_lsfCbTbl[i];
}
}
}
/*----------------------------------------------------------------*
* obtain synthesis and weighting filters form lsf coefficients
*---------------------------------------------------------------*/
void DecoderInterpolateLSF(
float *syntdenum, /* (o) synthesis filter coefficients */
float *weightdenum, /* (o) weighting denumerator
coefficients */
float *lsfdeq, /* (i) dequantized lsf coefficients */
int length, /* (i) length of lsf coefficient vector */
iLBC_Dec_Inst_t *iLBCdec_inst
/* (i) the decoder state structure */
){
int i, pos, lp_length;
float lp[LPC_FILTERORDER + 1], *lsfdeq2;
lsfdeq2 = lsfdeq + length;
lp_length = length + 1;
if (iLBCdec_inst->mode==30) {
/* sub-frame 1: Interpolation between old and first */
LSFinterpolate2a_dec(lp, iLBCdec_inst->lsfdeqold, lsfdeq,
lsf_weightTbl_30ms[0], length);
memcpy(syntdenum,lp,lp_length*sizeof(float));
bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM,
lp_length);
/* sub-frames 2 to 6: interpolation between first
and last LSF */
pos = lp_length;
for (i = 1; i < 6; i++) {
LSFinterpolate2a_dec(lp, lsfdeq, lsfdeq2,
lsf_weightTbl_30ms[i], length);
memcpy(syntdenum + pos,lp,lp_length*sizeof(float));
bwexpand(weightdenum + pos, lp,
LPC_CHIRP_WEIGHTDENUM, lp_length);
pos += lp_length;
}
}
else {
pos = 0;
for (i = 0; i < iLBCdec_inst->nsub; i++) {
LSFinterpolate2a_dec(lp, iLBCdec_inst->lsfdeqold,
lsfdeq, lsf_weightTbl_20ms[i], length);
memcpy(syntdenum+pos,lp,lp_length*sizeof(float));
bwexpand(weightdenum+pos, lp, LPC_CHIRP_WEIGHTDENUM,
lp_length);
pos += lp_length;
}
}
/* update memory */
if (iLBCdec_inst->mode==30)
memcpy(iLBCdec_inst->lsfdeqold, lsfdeq2,
length*sizeof(float));
else
memcpy(iLBCdec_inst->lsfdeqold, lsfdeq,
length*sizeof(float));
}
A.37. LPCencode.h
/****************************************************************** iLBC Speech Coder ANSI-C Source Code LPCencode.h Copyright (C) The Internet Society (2004). All Rights Reserved. ******************************************************************/ #ifndef __iLBC_LPCENCOD_H #define __iLBC_LPCENCOD_H void LPCencode( float *syntdenum, /* (i/o) synthesis filter coefficients before/after encoding */ float *weightdenum, /* (i/o) weighting denumerator coefficients before/after encoding */ int *lsf_index, /* (o) lsf quantization index */ float *data, /* (i) lsf coefficients to quantize */ iLBC_Enc_Inst_t *iLBCenc_inst /* (i/o) the encoder state structure */ ); #endifA.38. LPCencode.c
/****************************************************************** iLBC Speech Coder ANSI-C Source Code LPCencode.c Copyright (C) The Internet Society (2004). All Rights Reserved. ******************************************************************/ #include <string.h> #include "iLBC_define.h" #include "helpfun.h" #include "lsf.h" #include "constants.h"
/*----------------------------------------------------------------*
* lpc analysis (subrutine to LPCencode)
*---------------------------------------------------------------*/
void SimpleAnalysis(
float *lsf, /* (o) lsf coefficients */
float *data, /* (i) new data vector */
iLBC_Enc_Inst_t *iLBCenc_inst
/* (i/o) the encoder state structure */
){
int k, is;
float temp[BLOCKL_MAX], lp[LPC_FILTERORDER + 1];
float lp2[LPC_FILTERORDER + 1];
float r[LPC_FILTERORDER + 1];
is=LPC_LOOKBACK+BLOCKL_MAX-iLBCenc_inst->blockl;
memcpy(iLBCenc_inst->lpc_buffer+is,data,
iLBCenc_inst->blockl*sizeof(float));
/* No lookahead, last window is asymmetric */
for (k = 0; k < iLBCenc_inst->lpc_n; k++) {
is = LPC_LOOKBACK;
if (k < (iLBCenc_inst->lpc_n - 1)) {
window(temp, lpc_winTbl,
iLBCenc_inst->lpc_buffer, BLOCKL_MAX);
} else {
window(temp, lpc_asymwinTbl,
iLBCenc_inst->lpc_buffer + is, BLOCKL_MAX);
}
autocorr(r, temp, BLOCKL_MAX, LPC_FILTERORDER);
window(r, r, lpc_lagwinTbl, LPC_FILTERORDER + 1);
levdurb(lp, temp, r, LPC_FILTERORDER);
bwexpand(lp2, lp, LPC_CHIRP_SYNTDENUM, LPC_FILTERORDER+1);
a2lsf(lsf + k*LPC_FILTERORDER, lp2);
}
is=LPC_LOOKBACK+BLOCKL_MAX-iLBCenc_inst->blockl;
memmove(iLBCenc_inst->lpc_buffer,
iLBCenc_inst->lpc_buffer+LPC_LOOKBACK+BLOCKL_MAX-is,
is*sizeof(float));
}
/*----------------------------------------------------------------*
* lsf interpolator and conversion from lsf to a coefficients
* (subrutine to SimpleInterpolateLSF)
*---------------------------------------------------------------*/
void LSFinterpolate2a_enc(
float *a, /* (o) lpc coefficients */
float *lsf1,/* (i) first set of lsf coefficients */
float *lsf2,/* (i) second set of lsf coefficients */
float coef, /* (i) weighting coefficient to use between
lsf1 and lsf2 */
long length /* (i) length of coefficient vectors */
){
float lsftmp[LPC_FILTERORDER];
interpolate(lsftmp, lsf1, lsf2, coef, length);
lsf2a(a, lsftmp);
}
/*----------------------------------------------------------------*
* lsf interpolator (subrutine to LPCencode)
*---------------------------------------------------------------*/
void SimpleInterpolateLSF(
float *syntdenum, /* (o) the synthesis filter denominator
resulting from the quantized
interpolated lsf */
float *weightdenum, /* (o) the weighting filter denominator
resulting from the unquantized
interpolated lsf */
float *lsf, /* (i) the unquantized lsf coefficients */
float *lsfdeq, /* (i) the dequantized lsf coefficients */
float *lsfold, /* (i) the unquantized lsf coefficients of
the previous signal frame */
float *lsfdeqold, /* (i) the dequantized lsf coefficients of
the previous signal frame */
int length, /* (i) should equate LPC_FILTERORDER */
iLBC_Enc_Inst_t *iLBCenc_inst
/* (i/o) the encoder state structure */
){
int i, pos, lp_length;
float lp[LPC_FILTERORDER + 1], *lsf2, *lsfdeq2;
lsf2 = lsf + length;
lsfdeq2 = lsfdeq + length;
lp_length = length + 1;
if (iLBCenc_inst->mode==30) {
/* sub-frame 1: Interpolation between old and first
set of lsf coefficients */
LSFinterpolate2a_enc(lp, lsfdeqold, lsfdeq,
lsf_weightTbl_30ms[0], length);
memcpy(syntdenum,lp,lp_length*sizeof(float));
LSFinterpolate2a_enc(lp, lsfold, lsf,
lsf_weightTbl_30ms[0], length);
bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM, lp_length);
/* sub-frame 2 to 6: Interpolation between first
and second set of lsf coefficients */
pos = lp_length;
for (i = 1; i < iLBCenc_inst->nsub; i++) {
LSFinterpolate2a_enc(lp, lsfdeq, lsfdeq2,
lsf_weightTbl_30ms[i], length);
memcpy(syntdenum + pos,lp,lp_length*sizeof(float));
LSFinterpolate2a_enc(lp, lsf, lsf2,
lsf_weightTbl_30ms[i], length);
bwexpand(weightdenum + pos, lp,
LPC_CHIRP_WEIGHTDENUM, lp_length);
pos += lp_length;
}
}
else {
pos = 0;
for (i = 0; i < iLBCenc_inst->nsub; i++) {
LSFinterpolate2a_enc(lp, lsfdeqold, lsfdeq,
lsf_weightTbl_20ms[i], length);
memcpy(syntdenum+pos,lp,lp_length*sizeof(float));
LSFinterpolate2a_enc(lp, lsfold, lsf,
lsf_weightTbl_20ms[i], length);
bwexpand(weightdenum+pos, lp,
LPC_CHIRP_WEIGHTDENUM, lp_length);
pos += lp_length;
}
}
/* update memory */
if (iLBCenc_inst->mode==30) {
memcpy(lsfold, lsf2, length*sizeof(float));
memcpy(lsfdeqold, lsfdeq2, length*sizeof(float));
}
else {
memcpy(lsfold, lsf, length*sizeof(float));
memcpy(lsfdeqold, lsfdeq, length*sizeof(float));
}
}
/*----------------------------------------------------------------*
* lsf quantizer (subrutine to LPCencode)
*---------------------------------------------------------------*/
void SimplelsfQ(
float *lsfdeq, /* (o) dequantized lsf coefficients
(dimension FILTERORDER) */
int *index, /* (o) quantization index */
float *lsf, /* (i) the lsf coefficient vector to be
quantized (dimension FILTERORDER ) */
int lpc_n /* (i) number of lsf sets to quantize */
){
/* Quantize first LSF with memoryless split VQ */
SplitVQ(lsfdeq, index, lsf, lsfCbTbl, LSF_NSPLIT,
dim_lsfCbTbl, size_lsfCbTbl);
if (lpc_n==2) {
/* Quantize second LSF with memoryless split VQ */
SplitVQ(lsfdeq + LPC_FILTERORDER, index + LSF_NSPLIT,
lsf + LPC_FILTERORDER, lsfCbTbl, LSF_NSPLIT,
dim_lsfCbTbl, size_lsfCbTbl);
}
}
/*----------------------------------------------------------------*
* lpc encoder
*---------------------------------------------------------------*/
void LPCencode(
float *syntdenum, /* (i/o) synthesis filter coefficients
before/after encoding */
float *weightdenum, /* (i/o) weighting denumerator
coefficients before/after
encoding */
int *lsf_index, /* (o) lsf quantization index */
float *data, /* (i) lsf coefficients to quantize */
iLBC_Enc_Inst_t *iLBCenc_inst
/* (i/o) the encoder state structure */
){
float lsf[LPC_FILTERORDER * LPC_N_MAX];
float lsfdeq[LPC_FILTERORDER * LPC_N_MAX];
int change=0;
SimpleAnalysis(lsf, data, iLBCenc_inst);
SimplelsfQ(lsfdeq, lsf_index, lsf, iLBCenc_inst->lpc_n);
change=LSF_check(lsfdeq, LPC_FILTERORDER, iLBCenc_inst->lpc_n);
SimpleInterpolateLSF(syntdenum, weightdenum,
lsf, lsfdeq, iLBCenc_inst->lsfold,
iLBCenc_inst->lsfdeqold, LPC_FILTERORDER, iLBCenc_inst);
}
A.39. lsf.h
/******************************************************************
iLBC Speech Coder ANSI-C Source Code
lsf.h
Copyright (C) The Internet Society (2004).
All Rights Reserved.
******************************************************************/
#ifndef __iLBC_LSF_H
#define __iLBC_LSF_H
void a2lsf(
float *freq,/* (o) lsf coefficients */
float *a /* (i) lpc coefficients */
);
void lsf2a(
float *a_coef, /* (o) lpc coefficients */
float *freq /* (i) lsf coefficients */
);
#endif
A.40. lsf.c
/******************************************************************
iLBC Speech Coder ANSI-C Source Code
lsf.c
Copyright (C) The Internet Society (2004).
All Rights Reserved.
******************************************************************/
#include <string.h>
#include <math.h>
#include "iLBC_define.h"
/*----------------------------------------------------------------*
* conversion from lpc coefficients to lsf coefficients
*---------------------------------------------------------------*/
void a2lsf(
float *freq,/* (o) lsf coefficients */
float *a /* (i) lpc coefficients */
){
float steps[LSF_NUMBER_OF_STEPS] =
{(float)0.00635, (float)0.003175, (float)0.0015875,
(float)0.00079375};
float step;
int step_idx;
int lsp_index;
float p[LPC_HALFORDER];
float q[LPC_HALFORDER];
float p_pre[LPC_HALFORDER];
float q_pre[LPC_HALFORDER];
float old_p, old_q, *old;
float *pq_coef;
float omega, old_omega;
int i;
float hlp, hlp1, hlp2, hlp3, hlp4, hlp5;
for (i=0; i<LPC_HALFORDER; i++) {
p[i] = (float)-1.0 * (a[i + 1] + a[LPC_FILTERORDER - i]);
q[i] = a[LPC_FILTERORDER - i] - a[i + 1];
}
p_pre[0] = (float)-1.0 - p[0];
p_pre[1] = - p_pre[0] - p[1];
p_pre[2] = - p_pre[1] - p[2];
p_pre[3] = - p_pre[2] - p[3];
p_pre[4] = - p_pre[3] - p[4];
p_pre[4] = p_pre[4] / 2;
q_pre[0] = (float)1.0 - q[0];
q_pre[1] = q_pre[0] - q[1];
q_pre[2] = q_pre[1] - q[2];
q_pre[3] = q_pre[2] - q[3];
q_pre[4] = q_pre[3] - q[4];
q_pre[4] = q_pre[4] / 2;
omega = 0.0;
old_omega = 0.0;
old_p = FLOAT_MAX;
old_q = FLOAT_MAX;
/* Here we loop through lsp_index to find all the
LPC_FILTERORDER roots for omega. */
for (lsp_index = 0; lsp_index<LPC_FILTERORDER; lsp_index++) {
/* Depending on lsp_index being even or odd, we
alternatively solve the roots for the two LSP equations. */
if ((lsp_index & 0x1) == 0) {
pq_coef = p_pre;
old = &old_p;
} else {
pq_coef = q_pre;
old = &old_q;
}
/* Start with low resolution grid */
for (step_idx = 0, step = steps[step_idx];
step_idx < LSF_NUMBER_OF_STEPS;){
/* cos(10piw) + pq(0)cos(8piw) + pq(1)cos(6piw) +
pq(2)cos(4piw) + pq(3)cod(2piw) + pq(4) */
hlp = (float)cos(omega * TWO_PI);
hlp1 = (float)2.0 * hlp + pq_coef[0];
hlp2 = (float)2.0 * hlp * hlp1 - (float)1.0 +
pq_coef[1];
hlp3 = (float)2.0 * hlp * hlp2 - hlp1 + pq_coef[2];
hlp4 = (float)2.0 * hlp * hlp3 - hlp2 + pq_coef[3];
hlp5 = hlp * hlp4 - hlp3 + pq_coef[4];
if (((hlp5 * (*old)) <= 0.0) || (omega >= 0.5)){
if (step_idx == (LSF_NUMBER_OF_STEPS - 1)){
if (fabs(hlp5) >= fabs(*old)) {
freq[lsp_index] = omega - step;
} else {
freq[lsp_index] = omega;
}
if ((*old) >= 0.0){
*old = (float)-1.0 * FLOAT_MAX;
} else {
*old = FLOAT_MAX;
}
omega = old_omega;
step_idx = 0;
step_idx = LSF_NUMBER_OF_STEPS;
} else {
if (step_idx == 0) {
old_omega = omega;
}
step_idx++;
omega -= steps[step_idx];
/* Go back one grid step */
step = steps[step_idx];
}
} else {
/* increment omega until they are of different sign,
and we know there is at least one root between omega
and old_omega */
*old = hlp5;
omega += step;
}
}
}
for (i = 0; i<LPC_FILTERORDER; i++) {
freq[i] = freq[i] * TWO_PI;
}
}
/*----------------------------------------------------------------*
* conversion from lsf coefficients to lpc coefficients
*---------------------------------------------------------------*/
void lsf2a(
float *a_coef, /* (o) lpc coefficients */
float *freq /* (i) lsf coefficients */
){
int i, j;
float hlp;
float p[LPC_HALFORDER], q[LPC_HALFORDER];
float a[LPC_HALFORDER + 1], a1[LPC_HALFORDER],
a2[LPC_HALFORDER];
float b[LPC_HALFORDER + 1], b1[LPC_HALFORDER],
b2[LPC_HALFORDER];
for (i=0; i<LPC_FILTERORDER; i++) {
freq[i] = freq[i] * PI2;
}
/* Check input for ill-conditioned cases. This part is not
found in the TIA standard. It involves the following 2 IF
blocks. If "freq" is judged ill-conditioned, then we first
modify freq[0] and freq[LPC_HALFORDER-1] (normally
LPC_HALFORDER = 10 for LPC applications), then we adjust
the other "freq" values slightly */
if ((freq[0] <= 0.0) || (freq[LPC_FILTERORDER - 1] >= 0.5)){
if (freq[0] <= 0.0) {
freq[0] = (float)0.022;
}
if (freq[LPC_FILTERORDER - 1] >= 0.5) {
freq[LPC_FILTERORDER - 1] = (float)0.499;
}
hlp = (freq[LPC_FILTERORDER - 1] - freq[0]) /
(float) (LPC_FILTERORDER - 1);
for (i=1; i<LPC_FILTERORDER; i++) {
freq[i] = freq[i - 1] + hlp;
}
}
memset(a1, 0, LPC_HALFORDER*sizeof(float));
memset(a2, 0, LPC_HALFORDER*sizeof(float));
memset(b1, 0, LPC_HALFORDER*sizeof(float));
memset(b2, 0, LPC_HALFORDER*sizeof(float));
memset(a, 0, (LPC_HALFORDER+1)*sizeof(float));
memset(b, 0, (LPC_HALFORDER+1)*sizeof(float));
/* p[i] and q[i] compute cos(2*pi*omega_{2j}) and
cos(2*pi*omega_{2j-1} in eqs. 4.2.2.2-1 and 4.2.2.2-2.
Note that for this code p[i] specifies the coefficients
used in .Q_A(z) while q[i] specifies the coefficients used
in .P_A(z) */
for (i=0; i<LPC_HALFORDER; i++) {
p[i] = (float)cos(TWO_PI * freq[2 * i]);
q[i] = (float)cos(TWO_PI * freq[2 * i + 1]);
}
a[0] = 0.25;
b[0] = 0.25;
for (i= 0; i<LPC_HALFORDER; i++) {
a[i + 1] = a[i] - 2 * p[i] * a1[i] + a2[i];
b[i + 1] = b[i] - 2 * q[i] * b1[i] + b2[i];
a2[i] = a1[i];
a1[i] = a[i];
b2[i] = b1[i];
b1[i] = b[i];
}
for (j=0; j<LPC_FILTERORDER; j++) {
if (j == 0) {
a[0] = 0.25;
b[0] = -0.25;
} else {
a[0] = b[0] = 0.0;
}
for (i=0; i<LPC_HALFORDER; i++) {
a[i + 1] = a[i] - 2 * p[i] * a1[i] + a2[i];
b[i + 1] = b[i] - 2 * q[i] * b1[i] + b2[i];
a2[i] = a1[i];
a1[i] = a[i];
b2[i] = b1[i];
b1[i] = b[i];
}
a_coef[j + 1] = 2 * (a[LPC_HALFORDER] + b[LPC_HALFORDER]);
}
a_coef[0] = 1.0;
}
A.41. packing.h
/****************************************************************** iLBC Speech Coder ANSI-C Source Code packing.h Copyright (C) The Internet Society (2004). All Rights Reserved. ******************************************************************/ #ifndef __PACKING_H #define __PACKING_H void packsplit( int *index, /* (i) the value to split */ int *firstpart, /* (o) the value specified by most significant bits */ int *rest, /* (o) the value specified by least significant bits */ int bitno_firstpart, /* (i) number of bits in most significant part */ int bitno_total /* (i) number of bits in full range of value */ ); void packcombine( int *index, /* (i/o) the msb value in the combined value out */ int rest, /* (i) the lsb value */ int bitno_rest /* (i) the number of bits in the lsb part */ ); void dopack( unsigned char **bitstream, /* (i/o) on entrance pointer to place in bitstream to pack new data, on exit pointer to place in bitstream to pack future data */ int index, /* (i) the value to pack */ int bitno, /* (i) the number of bits that the value will fit within */ int *pos /* (i/o) write position in the current byte */ );
void unpack(
unsigned char **bitstream, /* (i/o) on entrance pointer to
place in bitstream to
unpack new data from, on
exit pointer to place in
bitstream to unpack future
data from */
int *index, /* (o) resulting value */
int bitno, /* (i) number of bits used to
represent the value */
int *pos /* (i/o) read position in the
current byte */
);
#endif
A.42. packing.c
/******************************************************************
iLBC Speech Coder ANSI-C Source Code
packing.c
Copyright (C) The Internet Society (2004).
All Rights Reserved.
******************************************************************/
#include <math.h>
#include <stdlib.h>
#include "iLBC_define.h"
#include "constants.h"
#include "helpfun.h"
#include "string.h"
/*----------------------------------------------------------------*
* splitting an integer into first most significant bits and
* remaining least significant bits
*---------------------------------------------------------------*/
void packsplit(
int *index, /* (i) the value to split */
int *firstpart, /* (o) the value specified by most
significant bits */
int *rest, /* (o) the value specified by least
significant bits */
int bitno_firstpart, /* (i) number of bits in most
significant part */
int bitno_total /* (i) number of bits in full range
of value */
){
int bitno_rest = bitno_total-bitno_firstpart;
*firstpart = *index>>(bitno_rest);
*rest = *index-(*firstpart<<(bitno_rest));
}
/*----------------------------------------------------------------*
* combining a value corresponding to msb's with a value
* corresponding to lsb's
*---------------------------------------------------------------*/
void packcombine(
int *index, /* (i/o) the msb value in the
combined value out */
int rest, /* (i) the lsb value */
int bitno_rest /* (i) the number of bits in the
lsb part */
){
*index = *index<<bitno_rest;
*index += rest;
}
/*----------------------------------------------------------------*
* packing of bits into bitstream, i.e., vector of bytes
*---------------------------------------------------------------*/
void dopack(
unsigned char **bitstream, /* (i/o) on entrance pointer to
place in bitstream to pack
new data, on exit pointer
to place in bitstream to
pack future data */
int index, /* (i) the value to pack */
int bitno, /* (i) the number of bits that the
value will fit within */
int *pos /* (i/o) write position in the
current byte */
){
int posLeft;
/* Clear the bits before starting in a new byte */
if ((*pos)==0) {
**bitstream=0;
}
while (bitno>0) {
/* Jump to the next byte if end of this byte is reached*/
if (*pos==8) {
*pos=0;
(*bitstream)++;
**bitstream=0;
}
posLeft=8-(*pos);
/* Insert index into the bitstream */
if (bitno <= posLeft) {
**bitstream |= (unsigned char)(index<<(posLeft-bitno));
*pos+=bitno;
bitno=0;
} else {
**bitstream |= (unsigned char)(index>>(bitno-posLeft));
*pos=8;
index-=((index>>(bitno-posLeft))<<(bitno-posLeft));
bitno-=posLeft;
}
}
}
/*----------------------------------------------------------------*
* unpacking of bits from bitstream, i.e., vector of bytes
*---------------------------------------------------------------*/
void unpack(
unsigned char **bitstream, /* (i/o) on entrance pointer to
place in bitstream to
unpack new data from, on
exit pointer to place in
bitstream to unpack future
data from */
int *index, /* (o) resulting value */
int bitno, /* (i) number of bits used to
represent the value */
int *pos /* (i/o) read position in the
current byte */
){
int BitsLeft;
*index=0;
while (bitno>0) {
/* move forward in bitstream when the end of the
byte is reached */
if (*pos==8) {
*pos=0;
(*bitstream)++;
}
BitsLeft=8-(*pos);
/* Extract bits to index */
if (BitsLeft>=bitno) {
*index+=((((**bitstream)<<(*pos)) & 0xFF)>>(8-bitno));
*pos+=bitno;
bitno=0;
} else {
if ((8-bitno)>0) {
*index+=((((**bitstream)<<(*pos)) & 0xFF)>>
(8-bitno));
*pos=8;
} else {
*index+=(((int)(((**bitstream)<<(*pos)) & 0xFF))<<
(bitno-8));
*pos=8;
}
bitno-=BitsLeft;
}
}
}
A.43. StateConstructW.h
/******************************************************************
iLBC Speech Coder ANSI-C Source Code
StateConstructW.h
Copyright (C) The Internet Society (2004).
All Rights Reserved.
******************************************************************/
#ifndef __iLBC_STATECONSTRUCTW_H
#define __iLBC_STATECONSTRUCTW_H
void StateConstructW(
int idxForMax, /* (i) 6-bit index for the quantization of
max amplitude */
int *idxVec, /* (i) vector of quantization indexes */
float *syntDenum, /* (i) synthesis filter denumerator */
float *out, /* (o) the decoded state vector */
int len /* (i) length of a state vector */
);
#endif
A.44. StateConstructW.c
/******************************************************************
iLBC Speech Coder ANSI-C Source Code
StateConstructW.c
Copyright (C) The Internet Society (2004).
All Rights Reserved.
******************************************************************/
#include <math.h>
#include <string.h>
#include "iLBC_define.h"
#include "constants.h"
#include "filter.h"
/*----------------------------------------------------------------*
* decoding of the start state
*---------------------------------------------------------------*/
void StateConstructW(
int idxForMax, /* (i) 6-bit index for the quantization of
max amplitude */
int *idxVec, /* (i) vector of quantization indexes */
float *syntDenum, /* (i) synthesis filter denumerator */
float *out, /* (o) the decoded state vector */
int len /* (i) length of a state vector */
){
float maxVal, tmpbuf[LPC_FILTERORDER+2*STATE_LEN], *tmp,
numerator[LPC_FILTERORDER+1];
float foutbuf[LPC_FILTERORDER+2*STATE_LEN], *fout;
int k,tmpi;
/* decoding of the maximum value */
maxVal = state_frgqTbl[idxForMax];
maxVal = (float)pow(10,maxVal)/(float)4.5;
/* initialization of buffers and coefficients */
memset(tmpbuf, 0, LPC_FILTERORDER*sizeof(float));
memset(foutbuf, 0, LPC_FILTERORDER*sizeof(float));
for (k=0; k<LPC_FILTERORDER; k++) {
numerator[k]=syntDenum[LPC_FILTERORDER-k];
}
numerator[LPC_FILTERORDER]=syntDenum[0];
tmp = &tmpbuf[LPC_FILTERORDER];
fout = &foutbuf[LPC_FILTERORDER];
/* decoding of the sample values */
for (k=0; k<len; k++) {
tmpi = len-1-k;
/* maxVal = 1/scal */
tmp[k] = maxVal*state_sq3Tbl[idxVec[tmpi]];
}
/* circular convolution with all-pass filter */
memset(tmp+len, 0, len*sizeof(float));
ZeroPoleFilter(tmp, numerator, syntDenum, 2*len,
LPC_FILTERORDER, fout);
for (k=0;k<len;k++) {
out[k] = fout[len-1-k]+fout[2*len-1-k];
}
}
A.45. StateSearchW.h
/****************************************************************** iLBC Speech Coder ANSI-C Source Code StateSearchW.h Copyright (C) The Internet Society (2004). All Rights Reserved. ******************************************************************/ #ifndef __iLBC_STATESEARCHW_H #define __iLBC_STATESEARCHW_H void AbsQuantW( iLBC_Enc_Inst_t *iLBCenc_inst, /* (i) Encoder instance */ float *in, /* (i) vector to encode */ float *syntDenum, /* (i) denominator of synthesis filter */ float *weightDenum, /* (i) denominator of weighting filter */ int *out, /* (o) vector of quantizer indexes */ int len, /* (i) length of vector to encode and vector of quantizer indexes */ int state_first /* (i) position of start state in the 80 vec */ ); void StateSearchW( iLBC_Enc_Inst_t *iLBCenc_inst, /* (i) Encoder instance */ float *residual,/* (i) target residual vector */ float *syntDenum, /* (i) lpc synthesis filter */ float *weightDenum, /* (i) weighting filter denuminator */ int *idxForMax, /* (o) quantizer index for maximum amplitude */ int *idxVec, /* (o) vector of quantization indexes */ int len, /* (i) length of all vectors */ int state_first /* (i) position of start state in the 80 vec */ ); #endif
A.46. StateSearchW.c
/****************************************************************** iLBC Speech Coder ANSI-C Source Code StateSearchW.c Copyright (C) The Internet Society (2004). All Rights Reserved. ******************************************************************/ #include <math.h> #include <string.h> #include "iLBC_define.h" #include "constants.h" #include "filter.h" #include "helpfun.h" /*----------------------------------------------------------------* * predictive noise shaping encoding of scaled start state * (subrutine for StateSearchW) *---------------------------------------------------------------*/ void AbsQuantW( iLBC_Enc_Inst_t *iLBCenc_inst, /* (i) Encoder instance */ float *in, /* (i) vector to encode */ float *syntDenum, /* (i) denominator of synthesis filter */ float *weightDenum, /* (i) denominator of weighting filter */ int *out, /* (o) vector of quantizer indexes */ int len, /* (i) length of vector to encode and vector of quantizer indexes */ int state_first /* (i) position of start state in the 80 vec */ ){ float *syntOut; float syntOutBuf[LPC_FILTERORDER+STATE_SHORT_LEN_30MS]; float toQ, xq; int n; int index; /* initialization of buffer for filtering */ memset(syntOutBuf, 0, LPC_FILTERORDER*sizeof(float));
/* initialization of pointer for filtering */
syntOut = &syntOutBuf[LPC_FILTERORDER];
/* synthesis and weighting filters on input */
if (state_first) {
AllPoleFilter (in, weightDenum, SUBL, LPC_FILTERORDER);
} else {
AllPoleFilter (in, weightDenum,
iLBCenc_inst->state_short_len-SUBL,
LPC_FILTERORDER);
}
/* encoding loop */
for (n=0; n<len; n++) {
/* time update of filter coefficients */
if ((state_first)&&(n==SUBL)){
syntDenum += (LPC_FILTERORDER+1);
weightDenum += (LPC_FILTERORDER+1);
/* synthesis and weighting filters on input */
AllPoleFilter (&in[n], weightDenum, len-n,
LPC_FILTERORDER);
} else if ((state_first==0)&&
(n==(iLBCenc_inst->state_short_len-SUBL))) {
syntDenum += (LPC_FILTERORDER+1);
weightDenum += (LPC_FILTERORDER+1);
/* synthesis and weighting filters on input */
AllPoleFilter (&in[n], weightDenum, len-n,
LPC_FILTERORDER);
}
/* prediction of synthesized and weighted input */
syntOut[n] = 0.0;
AllPoleFilter (&syntOut[n], weightDenum, 1,
LPC_FILTERORDER);
/* quantization */
toQ = in[n]-syntOut[n];
sort_sq(&xq, &index, toQ, state_sq3Tbl, 8);
out[n]=index;
syntOut[n] = state_sq3Tbl[out[n]];
/* update of the prediction filter */
AllPoleFilter(&syntOut[n], weightDenum, 1,
LPC_FILTERORDER);
}
}
/*----------------------------------------------------------------*
* encoding of start state
*---------------------------------------------------------------*/
void StateSearchW(
iLBC_Enc_Inst_t *iLBCenc_inst,
/* (i) Encoder instance */
float *residual,/* (i) target residual vector */
float *syntDenum, /* (i) lpc synthesis filter */
float *weightDenum, /* (i) weighting filter denuminator */
int *idxForMax, /* (o) quantizer index for maximum
amplitude */
int *idxVec, /* (o) vector of quantization indexes */
int len, /* (i) length of all vectors */
int state_first /* (i) position of start state in the
80 vec */
){
float dtmp, maxVal;
float tmpbuf[LPC_FILTERORDER+2*STATE_SHORT_LEN_30MS];
float *tmp, numerator[1+LPC_FILTERORDER];
float foutbuf[LPC_FILTERORDER+2*STATE_SHORT_LEN_30MS], *fout;
int k;
float qmax, scal;
/* initialization of buffers and filter coefficients */
memset(tmpbuf, 0, LPC_FILTERORDER*sizeof(float));
memset(foutbuf, 0, LPC_FILTERORDER*sizeof(float));
for (k=0; k<LPC_FILTERORDER; k++) {
numerator[k]=syntDenum[LPC_FILTERORDER-k];
}
numerator[LPC_FILTERORDER]=syntDenum[0];
tmp = &tmpbuf[LPC_FILTERORDER];
fout = &foutbuf[LPC_FILTERORDER];
/* circular convolution with the all-pass filter */
memcpy(tmp, residual, len*sizeof(float));
memset(tmp+len, 0, len*sizeof(float));
ZeroPoleFilter(tmp, numerator, syntDenum, 2*len,
LPC_FILTERORDER, fout);
for (k=0; k<len; k++) {
fout[k] += fout[k+len];
}
/* identification of the maximum amplitude value */
maxVal = fout[0];
for (k=1; k<len; k++) {
if (fout[k]*fout[k] > maxVal*maxVal){
maxVal = fout[k];
}
}
maxVal=(float)fabs(maxVal);
/* encoding of the maximum amplitude value */
if (maxVal < 10.0) {
maxVal = 10.0;
}
maxVal = (float)log10(maxVal);
sort_sq(&dtmp, idxForMax, maxVal, state_frgqTbl, 64);
/* decoding of the maximum amplitude representation value,
and corresponding scaling of start state */
maxVal=state_frgqTbl[*idxForMax];
qmax = (float)pow(10,maxVal);
scal = (float)(4.5)/qmax;
for (k=0; k<len; k++){
fout[k] *= scal;
}
/* predictive noise shaping encoding of scaled start state */
AbsQuantW(iLBCenc_inst, fout,syntDenum,
weightDenum,idxVec, len, state_first);
}
A.47. syntFilter.h
/****************************************************************** iLBC Speech Coder ANSI-C Source Code syntFilter.h Copyright (C) The Internet Society (2004). All Rights Reserved. ******************************************************************/ #ifndef __iLBC_SYNTFILTER_H #define __iLBC_SYNTFILTER_H void syntFilter( float *Out, /* (i/o) Signal to be filtered */ float *a, /* (i) LP parameters */ int len, /* (i) Length of signal */ float *mem /* (i/o) Filter state */ ); #endifA.48. syntFilter.c
/****************************************************************** iLBC Speech Coder ANSI-C Source Code syntFilter.c Copyright (C) The Internet Society (2004). All Rights Reserved. ******************************************************************/ #include "iLBC_define.h" /*----------------------------------------------------------------* * LP synthesis filter. *---------------------------------------------------------------*/ void syntFilter( float *Out, /* (i/o) Signal to be filtered */ float *a, /* (i) LP parameters */ int len, /* (i) Length of signal */
float *mem /* (i/o) Filter state */
){
int i, j;
float *po, *pi, *pa, *pm;
po=Out;
/* Filter first part using memory from past */
for (i=0; i<LPC_FILTERORDER; i++) {
pi=&Out[i-1];
pa=&a[1];
pm=&mem[LPC_FILTERORDER-1];
for (j=1; j<=i; j++) {
*po-=(*pa++)*(*pi--);
}
for (j=i+1; j<LPC_FILTERORDER+1; j++) {
*po-=(*pa++)*(*pm--);
}
po++;
}
/* Filter last part where the state is entirely in
the output vector */
for (i=LPC_FILTERORDER; i<len; i++) {
pi=&Out[i-1];
pa=&a[1];
for (j=1; j<LPC_FILTERORDER+1; j++) {
*po-=(*pa++)*(*pi--);
}
po++;
}
/* Update state vector */
memcpy(mem, &Out[len-LPC_FILTERORDER],
LPC_FILTERORDER*sizeof(float));
}
Authors' Addresses
Soren Vang Andersen Department of Communication Technology Aalborg University Fredrik Bajers Vej 7A 9200 Aalborg Denmark Phone: ++45 9 6358627 EMail: sva@kom.auc.dk Alan Duric Telio AS Stoperigt. 2 Oslo, N-0250 Norway Phone: +47 21673555 EMail: alan.duric@telio.no Henrik Astrom Global IP Sound AB Olandsgatan 42 Stockholm, S-11663 Sweden Phone: +46 8 54553040 EMail: henrik.astrom@globalipsound.com Roar Hagen Global IP Sound AB Olandsgatan 42 Stockholm, S-11663 Sweden Phone: +46 8 54553040 EMail: roar.hagen@globalipsound.com
W. Bastiaan Kleijn Global IP Sound AB Olandsgatan 42 Stockholm, S-11663 Sweden Phone: +46 8 54553040 EMail: bastiaan.kleijn@globalipsound.com Jan Linden Global IP Sound Inc. 900 Kearny Street, suite 500 San Francisco, CA-94133 USA Phone: +1 415 397 2555 EMail: jan.linden@globalipsound.com
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