vdr/ac3dec/rematrix.c

/* 
 *    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;
		}
	}
}