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91 lines
4.5 KiB
91 lines
4.5 KiB
/*
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postProcessing.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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 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 "preProcessing.h"
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/*****************************************************************************/
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/* */
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/* Define filter coefficients */
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/* Coefficient are given by the filter transfert function : */
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/* */
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/* 0.46363718 - 0.92724705z(-1) + 0.46363718z(-2) */
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/* H(z) = −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− */
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/* 1 - 1.9059465z(-1) + 0.9114024z(-2) */
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/* */
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/* giving: */
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/* y[i] = B0*x[i] + B1*x[i-1] + B2*x[i-2] */
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/* + A1*y[i-1] + A2*y[i-2] */
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/* */
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/*****************************************************************************/
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/* coefficients are stored in Q1.13 */
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#define A1 ((word16_t)(15836))
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#define A2 ((word16_t)(-7667))
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#define B0 ((word16_t)(7699))
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#define B1 ((word16_t)(-15398))
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#define B2 ((word16_t)(7699))
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/* Initialization of context values */
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void initPostProcessing(bcg729DecoderChannelContextStruct *decoderChannelContext) {
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decoderChannelContext->outputY2 = 0;
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decoderChannelContext->outputY1 = 0;
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decoderChannelContext->inputX0 = 0;
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decoderChannelContext->inputX1 = 0;
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}
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/*****************************************************************************/
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/* postProcessing : high pass filtering and upscaling Spec 4.2.5 */
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/* Algorithm: */
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/* y[i] = BO*x[i] + B1*x[i-1] + B2*x[i-2] + A1*y[i-1] + A2*y[i-2] */
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/* parameters: */
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/* -(i/o) decoderChannelContext : the channel context data */
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/* -(i/o) signal : 40 values in Q0, reconstructed speech, output */
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/* replaces the input in buffer */
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/* */
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/*****************************************************************************/
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void postProcessing(bcg729DecoderChannelContextStruct *decoderChannelContext, word16_t signal[]) {
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int i;
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word16_t inputX2;
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word32_t acc; /* in Q13 */
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for(i=0; i<L_SUBFRAME; i++) {
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inputX2 = decoderChannelContext->inputX1;
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decoderChannelContext->inputX1 = decoderChannelContext->inputX0;
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decoderChannelContext->inputX0 = signal[i];
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/* compute with acc and coefficients in Q13 */
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acc = MULT16_32_Q13(A1, decoderChannelContext->outputY1); /* Y1 in Q14.13 * A1 in Q1.13 -> acc in Q17.13*/
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acc = MAC16_32_Q13(acc, A2, decoderChannelContext->outputY2); /* Y2 in Q14.13 * A2 in Q0.13 -> Q15.13 + acc in Q17.13 -> acc in Q18.12 */
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/* 3*(Xi in Q15.0 * Bi in Q0.13)->Q17.13 + acc in Q18.13 -> acc in 19.13(Overflow??) */
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acc = MAC16_16(acc, decoderChannelContext->inputX0, B0);
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acc = MAC16_16(acc, decoderChannelContext->inputX1, B1);
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acc = SATURATE(MAC16_16(acc, inputX2, B2), MAXINT29); /* saturate the acc to keep in Q15.13 */
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signal[i] = SATURATE(PSHR(acc,12), MAXINT16); /* acc in Q13 -> *2 and scale back to Q0 */
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decoderChannelContext->outputY2 = decoderChannelContext->outputY1;
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decoderChannelContext->outputY1 = acc;
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}
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return;
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}
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