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75 lines
2.2 KiB
C
75 lines
2.2 KiB
C
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/******************************************************************
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iLBC Speech Coder ANSI-C Source Code
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StateConstructW.c
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Copyright (C) The Internet Society (2004).
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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 "constants.h"
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#include "filter.h"
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/*----------------------------------------------------------------*
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* decoding of the start state
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*---------------------------------------------------------------*/
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void StateConstructW(
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int idxForMax, /* (i) 6-bit index for the quantization of
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max amplitude */
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int *idxVec, /* (i) vector of quantization indexes */
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float *syntDenum, /* (i) synthesis filter denumerator */
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float *out, /* (o) the decoded state vector */
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int len /* (i) length of a state vector */
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){
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float maxVal, tmpbuf[LPC_FILTERORDER+2*STATE_LEN], *tmp,
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numerator[LPC_FILTERORDER+1];
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float foutbuf[LPC_FILTERORDER+2*STATE_LEN], *fout;
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int k,tmpi;
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/* decoding of the maximum value */
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maxVal = state_frgqTbl[idxForMax];
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maxVal = (float)pow(10,maxVal)/(float)4.5;
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/* initialization of buffers and coefficients */
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memset(tmpbuf, 0, LPC_FILTERORDER*sizeof(float));
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memset(foutbuf, 0, LPC_FILTERORDER*sizeof(float));
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for (k=0; k<LPC_FILTERORDER; k++) {
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numerator[k]=syntDenum[LPC_FILTERORDER-k];
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}
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numerator[LPC_FILTERORDER]=syntDenum[0];
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tmp = &tmpbuf[LPC_FILTERORDER];
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fout = &foutbuf[LPC_FILTERORDER];
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/* decoding of the sample values */
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for (k=0; k<len; k++) {
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tmpi = len-1-k;
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/* maxVal = 1/scal */
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tmp[k] = maxVal*state_sq3Tbl[idxVec[tmpi]];
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}
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/* circular convolution with all-pass filter */
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memset(tmp+len, 0, len*sizeof(float));
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ZeroPoleFilter(tmp, numerator, syntDenum, 2*len,
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LPC_FILTERORDER, fout);
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for (k=0;k<len;k++) {
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out[k] = fout[len-1-k]+fout[2*len-1-k];
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}
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}
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