1 /*****************************************************************************
2 * ac3_decoder.c: core ac3 decoder
3 *****************************************************************************
4 * Copyright (C) 1999, 2000 VideoLAN
5 * $Id: ac3_decoder.c,v 1.33 2001/05/14 15:58:03 reno Exp $
7 * Authors: Michel Kaempf <maxx@via.ecp.fr>
8 * Michel Lespinasse <walken@zoy.org>
9 * Aaron Holtzman <aholtzma@engr.uvic.ca>
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
24 *****************************************************************************/
28 #include <string.h> /* memcpy() */
35 #include "intf_msg.h" /* intf_DbgMsg(), intf_ErrMsg() */
37 #include "stream_control.h"
38 #include "input_ext-dec.h"
40 #include "audio_output.h"
42 #include "ac3_decoder.h"
43 #include "ac3_decoder_thread.h" /* ac3dec_thread_t */
44 #include "ac3_internal.h"
46 static const float cmixlev_lut[4] = { 0.707, 0.595, 0.500, 0.707 };
47 static const float smixlev_lut[4] = { 0.707, 0.500, 0.0 , 0.500 };
49 int ac3_init (ac3dec_t * p_ac3dec)
51 p_ac3dec->mantissa.lfsr_state = 1; /* dither_gen initialization */
52 imdct_init(&p_ac3dec->imdct);
53 downmix_init(&p_ac3dec->downmix);
58 int ac3_decode_frame (ac3dec_t * p_ac3dec, s16 * buffer)
61 ac3dec_thread_t * p_ac3dec_t = (ac3dec_thread_t *) p_ac3dec->bit_stream.p_callback_arg;
63 if (parse_bsi (p_ac3dec))
65 intf_WarnMsg (3,"ac3dec warn: error during parsing");
66 parse_auxdata (p_ac3dec);
70 /* compute downmix parameters
71 * downmix to tow channels for now */
72 p_ac3dec->dm_par.clev = 0.0;
73 p_ac3dec->dm_par.slev = 0.0;
74 p_ac3dec->dm_par.unit = 1.0;
75 if (p_ac3dec->bsi.acmod & 0x1) /* have center */
76 p_ac3dec->dm_par.clev = cmixlev_lut[p_ac3dec->bsi.cmixlev];
78 if (p_ac3dec->bsi.acmod & 0x4) /* have surround channels */
79 p_ac3dec->dm_par.slev = smixlev_lut[p_ac3dec->bsi.surmixlev];
81 p_ac3dec->dm_par.unit /= 1.0 + p_ac3dec->dm_par.clev + p_ac3dec->dm_par.slev;
82 p_ac3dec->dm_par.clev *= p_ac3dec->dm_par.unit;
83 p_ac3dec->dm_par.slev *= p_ac3dec->dm_par.unit;
85 for (i = 0; i < 6; i++) {
86 /* Initialize freq/time sample storage */
87 memset(p_ac3dec->samples, 0, sizeof(float) * 256 *
88 (p_ac3dec->bsi.nfchans + p_ac3dec->bsi.lfeon));
91 if ((p_ac3dec_t->p_fifo->b_die) && (p_ac3dec_t->p_fifo->b_error))
96 if (parse_audblk (p_ac3dec, i))
98 intf_WarnMsg (3,"ac3dec warn: error during audioblock");
99 parse_auxdata (p_ac3dec);
103 if ((p_ac3dec_t->p_fifo->b_die) && (p_ac3dec_t->p_fifo->b_error))
108 if (exponent_unpack (p_ac3dec))
110 intf_WarnMsg (3,"ac3dec warn: error during unpack");
111 parse_auxdata (p_ac3dec);
114 bit_allocate (p_ac3dec);
115 mantissa_unpack (p_ac3dec);
117 if ((p_ac3dec_t->p_fifo->b_die) && (p_ac3dec_t->p_fifo->b_error))
122 if (p_ac3dec->bsi.acmod == 0x2)
124 imdct (p_ac3dec, buffer);
129 parse_auxdata (p_ac3dec);