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115 lines
5.9 KiB
115 lines
5.9 KiB
/*
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decodeGains.c
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Copyright (C) 2011 Belledonne Communications, Grenoble, France
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Author : Johan Pascal
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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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 General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include "typedef.h"
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#include "codecParameters.h"
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#include "basicOperationsMacros.h"
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#include "codebooks.h"
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#include "utils.h"
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#include "decodeGains.h"
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/* init function */
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void initDecodeGains(bcg729DecoderChannelContextStruct *decoderChannelContext)
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{
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/*init previousGainPredictionError to -14 in Q10 */
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decoderChannelContext->previousGainPredictionError[0] = -14336;
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decoderChannelContext->previousGainPredictionError[1] = -14336;
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decoderChannelContext->previousGainPredictionError[2] = -14336;
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decoderChannelContext->previousGainPredictionError[3] = -14336;
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}
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/*****************************************************************************/
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/* decodeGains : decode adaptive and fixed codebooks gains as in spec 4.1.5 */
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/* parameters: */
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/* -(i/o) decoderChannelContext : the channel context data */
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/* -(i) GA : parameter GA: Gain Codebook Stage 1 (3 bits) */
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/* -(i) GB : paremeter GB: Gain Codebook Stage 2 (4 bits) */
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/* -(i) fixedCodebookVector: 40 values current fixed Codebook vector */
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/* in Q1.13. */
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/* -(i) frameErasureFlag : set in case of frame erasure */
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/* -(i/o) adaptativeCodebookGain : input previous/output current */
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/* subframe Pitch Gain in Q14 */
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/* -(i/o) fixedCodebookGain : input previous/output current Fixed */
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/* Codebook Gain in Q1 */
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/* */
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/*****************************************************************************/
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void decodeGains (bcg729DecoderChannelContextStruct *decoderChannelContext, uint16_t GA, uint16_t GB, word16_t *fixedCodebookVector, uint8_t frameErasureFlag,
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word16_t *adaptativeCodebookGain, word16_t *fixedCodebookGain)
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{
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word32_t predictedFixedCodebookGain;
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word16_t fixedCodebookGainCorrectionFactor;
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/* check the erasure flag */
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if (frameErasureFlag != 0) { /* we have a frame erasure, proceed as described in spec 4.4.2 */
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int i;
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word32_t currentGainPredictionError =0;
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/* adaptativeCodebookGain as in eq94 */
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if (*adaptativeCodebookGain < 16384) { /* last subframe gain < 1 in Q14 */
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*adaptativeCodebookGain = MULT16_16_Q15(*adaptativeCodebookGain, 29491 ); /* *0.9 in Q15 */
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} else { /* bound current subframe gain to 0.9 (14746 in Q14) */
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*adaptativeCodebookGain = 14746;
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}
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/* fixedCodebookGain as in eq93 */
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*fixedCodebookGain = MULT16_16_Q15(*fixedCodebookGain, 32113 ); /* *0.98 in Q15 */
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/* And update the previousGainPredictionError according to spec 4.4.3 */
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for (i=0; i<4; i++) {
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currentGainPredictionError = ADD32(currentGainPredictionError, decoderChannelContext->previousGainPredictionError[i]); /* previousGainPredictionError in Q3.10-> Sum in Q5.10 (on 32 bits) */
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}
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currentGainPredictionError = PSHR(currentGainPredictionError,2); /* /4 -> Q3.10 */
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if (currentGainPredictionError < -10240) { /* final result is low bounded by -14, so check before doing -4 if it's over -10(-10240 in Q10) or not */
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currentGainPredictionError = -14336; /* set to -14 in Q10 */
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} else { /* substract 4 */
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currentGainPredictionError = SUB32(currentGainPredictionError,4096); /* in Q10 */
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}
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/* shift the array and insert the current Prediction Error */
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decoderChannelContext->previousGainPredictionError[3] = decoderChannelContext->previousGainPredictionError[2];
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decoderChannelContext->previousGainPredictionError[2] = decoderChannelContext->previousGainPredictionError[1];
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decoderChannelContext->previousGainPredictionError[1] = decoderChannelContext->previousGainPredictionError[0];
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decoderChannelContext->previousGainPredictionError[0] = (word16_t)currentGainPredictionError;
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return;
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}
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/* First recover the GA and GB real index from their mapping tables(spec 3.9.3) */
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GA = reverseIndexMappingGA[GA];
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GB = reverseIndexMappingGB[GB];
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/* Compute the adaptativeCodebookGain from the tables according to eq73 in spec3.9.2 */
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/* adaptativeCodebookGain = GACodebook[GA][0] + GBCodebook[GB][0] */
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*adaptativeCodebookGain = ADD16(GACodebook[GA][0], GBCodebook[GB][0]); /* result in Q1.14 */
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/* Fixed Codebook: MA code-gain prediction */
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predictedFixedCodebookGain = MACodeGainPrediction(decoderChannelContext->previousGainPredictionError, fixedCodebookVector); /* predictedFixedCodebookGain on 32 bits in Q11.16 */
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/* get fixed codebook gain correction factor(gama) from the codebooks GA and GB according to eq74 */
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fixedCodebookGainCorrectionFactor = ADD16(GACodebook[GA][1], GBCodebook[GB][1]); /* result in Q3.12 (range [0.185, 5.05])*/
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/* compute fixedCodebookGain according to eq74 */
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*fixedCodebookGain = (word16_t)PSHR(MULT16_32_Q12(fixedCodebookGainCorrectionFactor, predictedFixedCodebookGain), 15); /* Q11.16*Q3.12 -> Q14.16, shift by 15 to get a Q14.1 which fits on 16 bits */
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/* use eq72 to compute current prediction error in order to update the previousGainPredictionError array */
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computeGainPredictionError(fixedCodebookGainCorrectionFactor, decoderChannelContext->previousGainPredictionError);
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}
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