83 lines
2.7 KiB
C
83 lines
2.7 KiB
C
/*
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* iLBC - a library for the iLBC codec
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*
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* StateConstruct.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: StateConstructW.c,v 1.2 2008/03/06 12:27:37 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 "constants.h"
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#include "filter.h"
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#include "StateConstructW.h"
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/*----------------------------------------------------------------*
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* decoding of the start state
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*---------------------------------------------------------------*/
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void StateConstructW(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;
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float tmpbuf[ILBC_LPC_FILTERORDER + 2*STATE_LEN];
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float *tmp;
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float numerator[ILBC_LPC_FILTERORDER + 1];
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float foutbuf[ILBC_LPC_FILTERORDER + 2*STATE_LEN];
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float *fout;
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int k;
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int tmpi;
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/* decoding of the maximum value */
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maxVal = state_frgqTbl[idxForMax];
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maxVal = powf(10.0f, maxVal)/4.5f;
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/* initialization of buffers and coefficients */
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memset(tmpbuf, 0, ILBC_LPC_FILTERORDER*sizeof(float));
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memset(foutbuf, 0, ILBC_LPC_FILTERORDER*sizeof(float));
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for (k = 0; k < ILBC_LPC_FILTERORDER; k++)
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numerator[k] = syntDenum[ILBC_LPC_FILTERORDER - k];
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numerator[ILBC_LPC_FILTERORDER] = syntDenum[0];
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tmp = &tmpbuf[ILBC_LPC_FILTERORDER];
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fout = &foutbuf[ILBC_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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{
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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, ILBC_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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