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/*
* rematrix.c
*
* Copyright (C) Aaron Holtzman - July 1999
*
* This file is part of ac3dec, a free Dolby AC-3 stream decoder.
*
* ac3dec is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* ac3dec is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Make; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*
*
*/
#include <stdlib.h>
#include <stdio.h>
#include "ac3.h"
#include "ac3_internal.h"
#include "rematrix.h"
struct rematrix_band_s
{
uint32_t start;
uint32_t end;
} rematrix_band[] = {
{13, 24},
{25, 36},
{37, 60},
{61, 252}
};
/**
*
**/
inline uint32_t min (uint32_t a, uint32_t b)
{
return (a < b) ? a : b;
}
/**
* This routine simply does stereo remartixing for the 2 channel
* stereo mode
**/
void rematrix (audblk_t *audblk, stream_samples_t samples)
{
uint32_t num_bands;
uint32_t start;
uint32_t end;
int i,j;
if (!audblk->cplinu || audblk->cplbegf > 2)
num_bands = 4;
else if (audblk->cplbegf > 0)
num_bands = 3;
else
num_bands = 2;
for (i=0; i < num_bands; i++) {
if (!audblk->rematflg[i])
continue;
start = rematrix_band[i].start;
end = min (rematrix_band[i].end ,12 * audblk->cplbegf + 36);
for (j=start;j < end; j++) {
float left,right;
left = samples[0][j] + samples[1][j];
right = samples[0][j] - samples[1][j];
samples[0][j] = left;
samples[1][j] = right;
}
}
}
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