1 /*****************************************************************************
2 * ac3_rematrix.c: ac3 audio rematrixing
3 *****************************************************************************
4 * Copyright (C) 1999, 2000 VideoLAN
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
21 *****************************************************************************/
24 #include "int_types.h"
25 #include "ac3_decoder.h"
26 #include "ac3_internal.h"
28 struct rematrix_band_s {
33 static struct rematrix_band_s rematrix_band[] = { {13,24}, {25,36}, {37 ,60}, {61,252}};
35 static __inline__ u32 min (u32 a, u32 b)
37 return (a < b ? a : b);
40 /* This routine simply does stereo rematixing for the 2 channel
42 void rematrix (ac3dec_t * p_ac3dec)
50 if (p_ac3dec->audblk.cplinu || p_ac3dec->audblk.cplbegf > 2)
52 else if (p_ac3dec->audblk.cplbegf > 0)
57 for (i=0;i < num_bands; i++) {
58 if (!p_ac3dec->audblk.rematflg[i])
61 start = rematrix_band[i].start;
62 end = min(rematrix_band[i].end ,12 * p_ac3dec->audblk.cplbegf + 36);
64 for (j=start;j < end; j++) {
65 left = 0.5f * (p_ac3dec->coeffs.fbw[0][j] + p_ac3dec->coeffs.fbw[1][j]);
66 right = 0.5f * (p_ac3dec->coeffs.fbw[0][j] - p_ac3dec->coeffs.fbw[1][j]);
67 p_ac3dec->coeffs.fbw[0][j] = left;
68 p_ac3dec->coeffs.fbw[1][j] = right;