118 lines
3.2 KiB
C
118 lines
3.2 KiB
C
/*
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* iLBC - a library for the iLBC codec
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*
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* iCBConstruct.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: iCBConstruct.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 "ilbc.h"
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#include "gainquant.h"
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#include "getCBvec.h"
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#include "iCBConstruct.h"
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/*----------------------------------------------------------------*
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* Convert the codebook indexes to make the search easier
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*---------------------------------------------------------------*/
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void index_conv_enc(int *index) /* (i/o) Codebook indexes */
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{
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int k;
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for (k = 1; k < CB_NSTAGES; k++)
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{
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if ((index[k] >= 108) && (index[k] < 172))
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{
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index[k] -= 64;
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}
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else if (index[k] >= 236)
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{
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index[k] -= 128;
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}
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else
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{
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/* ERROR */
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}
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}
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}
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void index_conv_dec(int *index) /* (i/o) Codebook indexes */
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{
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int k;
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for (k = 1; k < CB_NSTAGES; k++)
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{
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if ((index[k] >= 44) && (index[k] < 108))
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{
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index[k] += 64;
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}
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else if ((index[k] >= 108) && (index[k] < 128))
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{
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index[k] += 128;
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}
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else
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{
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/* ERROR */
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}
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}
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}
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/*----------------------------------------------------------------*
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* Construct decoded vector from codebook and gains.
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*---------------------------------------------------------------*/
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void iCBConstruct(float *decvector, /* (o) Decoded vector */
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int *index, /* (i) Codebook indices */
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int *gain_index, /* (i) Gain quantization indices */
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float *mem, /* (i) Buffer for codevector construction */
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int lMem, /* (i) Length of buffer */
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int veclen, /* (i) Length of vector */
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int nStages) /* (i) Number of codebook stages */
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{
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int j;
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int k;
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float gain[CB_NSTAGES];
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float cbvec[SUBL];
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/* Gain de-quantization */
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gain[0] = gaindequant(gain_index[0], 1.0, 32);
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if (nStages > 1)
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gain[1] = gaindequant(gain_index[1], fabsf(gain[0]), 16);
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if (nStages > 2)
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gain[2] = gaindequant(gain_index[2], fabsf(gain[1]), 8);
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/* Codebook vector construction and construction of total vector */
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getCBvec(cbvec, mem, index[0], lMem, veclen);
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for (j = 0; j < veclen; j++)
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decvector[j] = gain[0]*cbvec[j];
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if (nStages > 1)
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{
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for (k = 1; k < nStages; k++)
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{
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getCBvec(cbvec, mem, index[k], lMem, veclen);
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for (j = 0; j < veclen; j++)
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decvector[j] += gain[k]*cbvec[j];
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}
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}
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}
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