mirror of
https://github.com/asterisk/asterisk.git
synced 2025-11-04 05:15:22 +00:00
75 lines
2.2 KiB
C
75 lines
2.2 KiB
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];
|
|
}
|
|
}
|