117 lines
3.3 KiB
C
117 lines
3.3 KiB
C
/*
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* broadvoice - a library for the BroadVoice 16 and 32 codecs
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*
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* gainquan.c - Quantize gains.
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*
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* Adapted by Steve Underwood <steveu@coppice.org> from code which is
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* Copyright 2000-2009 Broadcom Corporation
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License version 2.1,
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* as published by the Free Software Foundation.
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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. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id: bv32gainquan.c,v 1.1.1.1 2009/11/19 12:10:48 steveu Exp $
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*/
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/*! \file */
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#if defined(HAVE_CONFIG_H)
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#include "config.h"
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#endif
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#include <math.h>
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#include "typedef.h"
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#include "bv32externs.h"
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int bv32_gainquan(Float *gainq,
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Float lg,
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Float *lgpm,
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Float *prevlg, /* previous log gains (last two frames) */
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Float level) /* input level estimate */
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{
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Float elg;
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Float lgpe;
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Float limit;
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Float dmin;
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Float d;
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int i;
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int n;
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int gidx = 0;
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const int *p_gidx;
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/* CALCULATE ESTIMATED LOG-GAIN */
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elg = bv32_lgmean;
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for (i = 0; i < LGPORDER; i++)
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elg += bv32_lgp[i]*lgpm[i];
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/* SUBTRACT LOG-GAIN MEAN & ESTIMATED LOG-GAIN TO GET PREDICTION ERROR */
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lgpe = lg - elg;
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/* SCALAR QUANTIZATION OF LOG-GAIN PREDICTION ERROR */
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dmin = 1e30;
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p_gidx = bv32_idxord;
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for (i = 0; i < LGPECBSZ; i++)
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{
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d = lgpe - bv32_lgpecb[*p_gidx++];
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if (d < 0.0F)
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{
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d = -d;
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}
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if (d < dmin)
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{
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dmin = d;
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/* index into ordered codebook */
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gidx=i;
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}
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}
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/* CALCULATE QUANTIZED LOG-GAIN */
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*gainq = bv32_lgpecb[bv32_idxord[gidx]] + elg;
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/* LOOK UP FROM lgclimit() TABLE THE MAXIMUM LOG GAIN CHANGE ALLOWED */
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i = (int) ((prevlg[0] - level - LGLB) * 0.5F); /* get column index */
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if (i >= NGB)
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i = NGB - 1;
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else if (i < 0)
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i = 0;
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n = (int) ((prevlg[0] - prevlg[1] - GCLB) * 0.5F); /* get row index */
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if (n >= NGCB)
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n = NGCB - 1;
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else if (n < 0)
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n = 0;
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i = i*NGCB + n;
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/* CHECK WHETHER QUANTIZED LOG-GAIN CAUSE A GAIN CHANGE > LGCLIMIT */
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limit = prevlg[0] + bv32_lgclimit[i];/* limit that log-gain shouldn't exceed */
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while (*gainq > limit && gidx > 0) /* if quantized gain exceeds limit */
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{
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gidx -= 1; /* decrement gain quantizer index by 1 */
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*gainq = bv32_lgpecb[bv32_idxord[gidx]] + elg; /* use next quantizer output*/
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}
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/* get true codebook index */
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gidx = bv32_idxord[gidx];
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/* UPDATE LOG-GAIN PREDICTOR MEMORY */
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prevlg[1] = prevlg[0];
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prevlg[0] = *gainq;
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for (i = LGPORDER - 1; i > 0; i--)
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lgpm[i] = lgpm[i - 1];
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lgpm[0] = bv32_lgpecb[gidx];
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/* CONVERT QUANTIZED LOG-GAIN TO LINEAR DOMAIN */
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*gainq = pow(2.0F, 0.5F * *gainq);
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return gidx;
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}
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