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 GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public
19 * License along with this program; if not, write to the
20 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
21 * Boston, MA 02111-1307, USA.
22 *****************************************************************************/
25 #include "int_types.h"
26 #include "ac3_decoder.h"
27 #include "ac3_internal.h"
29 struct rematrix_band_s {
34 static struct rematrix_band_s rematrix_band[] = { {13,24}, {25,36}, {37 ,60}, {61,252}};
36 static __inline__ u32 min (u32 a, u32 b)
38 return (a < b ? a : b);
41 /* This routine simply does stereo rematixing for the 2 channel
43 void rematrix (ac3dec_t * p_ac3dec)
51 if (p_ac3dec->audblk.cplinu || p_ac3dec->audblk.cplbegf > 2)
53 else if (p_ac3dec->audblk.cplbegf > 0)
58 for (i=0;i < num_bands; i++) {
59 if (!p_ac3dec->audblk.rematflg[i])
62 start = rematrix_band[i].start;
63 end = min(rematrix_band[i].end ,12 * p_ac3dec->audblk.cplbegf + 36);
65 for (j=start;j < end; j++) {
66 left = 0.5f * (p_ac3dec->coeffs.fbw[0][j] + p_ac3dec->coeffs.fbw[1][j]);
67 right = 0.5f * (p_ac3dec->coeffs.fbw[0][j] - p_ac3dec->coeffs.fbw[1][j]);
68 p_ac3dec->coeffs.fbw[0][j] = left;
69 p_ac3dec->coeffs.fbw[1][j] = right;