1 /*****************************************************************************
2 * ac3_decoder.c: core ac3 decoder
3 *****************************************************************************
4 * Copyright (C) 1999, 2000 VideoLAN
5 * $Id: ac3_decoder.c,v 1.30 2001/04/30 21:04:20 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 *****************************************************************************/
33 #include "intf_msg.h" /* intf_DbgMsg(), intf_ErrMsg() */
35 #include "stream_control.h"
36 #include "input_ext-dec.h"
37 #include "audio_output.h"
40 #include "ac3_decoder.h"
41 #include "ac3_decoder_thread.h"
43 #include "ac3_internal.h"
47 void imdct_init (imdct_t * p_imdct);
48 void downmix_init (downmix_t * p_downmix);
50 static float cmixlev_lut[4] = { 0.707, 0.595, 0.500, 0.707 };
51 static float smixlev_lut[4] = { 0.707, 0.500, 0.0 , 0.500 };
53 int ac3_init (ac3dec_t * p_ac3dec)
55 // p_ac3dec->bit_stream.buffer = 0;
56 // p_ac3dec->bit_stream.i_available = 0;
57 p_ac3dec->mantissa.lfsr_state = 1; /* dither_gen initialization */
58 imdct_init(&p_ac3dec->imdct);
59 downmix_init(&p_ac3dec->downmix);
64 int ac3_decode_frame (ac3dec_t * p_ac3dec, s16 * buffer)
67 ac3dec_thread_t * p_ac3dec_t = (ac3dec_thread_t *) p_ac3dec->bit_stream.p_callback_arg;
69 if (parse_bsi (p_ac3dec))
71 intf_WarnMsg (1,"Error during ac3parsing");
72 parse_auxdata (p_ac3dec);
76 /* compute downmix parameters
77 * downmix to tow channels for now */
78 p_ac3dec->dm_par.clev = 0.0;
79 p_ac3dec->dm_par.slev = 0.0;
80 p_ac3dec->dm_par.unit = 1.0;
81 if (p_ac3dec->bsi.acmod & 0x1) /* have center */
82 p_ac3dec->dm_par.clev = cmixlev_lut[p_ac3dec->bsi.cmixlev];
84 if (p_ac3dec->bsi.acmod & 0x4) /* have surround channels */
85 p_ac3dec->dm_par.slev = smixlev_lut[p_ac3dec->bsi.surmixlev];
87 p_ac3dec->dm_par.unit /= 1.0 + p_ac3dec->dm_par.clev + p_ac3dec->dm_par.slev;
88 p_ac3dec->dm_par.clev *= p_ac3dec->dm_par.unit;
89 p_ac3dec->dm_par.slev *= p_ac3dec->dm_par.unit;
91 for (i = 0; i < 6; i++) {
92 /* Initialize freq/time sample storage */
93 memset(p_ac3dec->samples, 0, sizeof(float) * 256 *
94 (p_ac3dec->bsi.nfchans + p_ac3dec->bsi.lfeon));
97 if ((p_ac3dec_t->p_fifo->b_die) && (p_ac3dec_t->p_fifo->b_error))
102 if (parse_audblk (p_ac3dec, i))
104 intf_WarnMsg (1,"Error during ac3audioblock");
105 parse_auxdata (p_ac3dec);
109 if ((p_ac3dec_t->p_fifo->b_die) && (p_ac3dec_t->p_fifo->b_error))
114 if (exponent_unpack (p_ac3dec))
116 intf_WarnMsg (1,"Error during ac3unpack");
117 parse_auxdata (p_ac3dec);
120 bit_allocate (p_ac3dec);
121 mantissa_unpack (p_ac3dec);
123 if ((p_ac3dec_t->p_fifo->b_die) && (p_ac3dec_t->p_fifo->b_error))
128 if (p_ac3dec->bsi.acmod == 0x2)
130 imdct (p_ac3dec, buffer);
135 parse_auxdata (p_ac3dec);