src/ac3_decoder/ac3_decoder.c

   1 /*****************************************************************************
   2  * ac3_decoder.c: core ac3 decoder
   3  *****************************************************************************
   4  * Copyright (C) 1999, 2000 VideoLAN
   5  * $Id: ac3_decoder.c,v 1.34 2001/05/15 16:19:42 sam Exp $
   6  *
   7  * Authors: Michel Kaempf <maxx@via.ecp.fr>
   8  *          Michel Lespinasse <walken@zoy.org>
   9  *          Aaron Holtzman <aholtzma@engr.uvic.ca>
  10  *
  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.
  15  *
  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.
  20  *
  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  *****************************************************************************/
  25
  26 /*****************************************************************************
  27  * Preamble
  28  *****************************************************************************/
  29 #include "defs.h"
  30
  31 #include <string.h>                                              /* memcpy() */
  32
  33 #include "config.h"
  34 #include "common.h"
  35 #include "threads.h"
  36 #include "mtime.h"
  37
  38 #include "intf_msg.h"                        /* intf_DbgMsg(), intf_ErrMsg() */
  39
  40 #include "stream_control.h"
  41 #include "input_ext-dec.h"
  42
  43 #include "audio_output.h"
  44
  45 #include "ac3_imdct.h"
  46 #include "ac3_downmix.h"
  47 #include "ac3_decoder.h"
  48 #include "ac3_decoder_thread.h"                           /* ac3dec_thread_t */
  49
  50 #include "ac3_internal.h"
  51
  52 static const float cmixlev_lut[4] = { 0.707, 0.595, 0.500, 0.707 };
  53 static const float smixlev_lut[4] = { 0.707, 0.500, 0.0  , 0.500 };
  54
  55 int ac3_init (ac3dec_t * p_ac3dec)
  56 {
  57     p_ac3dec->mantissa.lfsr_state = 1;          /* dither_gen initialization */
  58     imdct_init(&p_ac3dec->imdct);
  59
  60     return 0;
  61 }
  62
  63 int ac3_decode_frame (ac3dec_t * p_ac3dec, s16 * buffer)
  64 {
  65     int i;
  66     ac3dec_thread_t * p_ac3thread = (ac3dec_thread_t *) p_ac3dec->bit_stream.p_callback_arg;
  67
  68     if (parse_bsi (p_ac3dec))
  69     {
  70         intf_WarnMsg (3,"ac3dec warn: error during parsing");
  71         parse_auxdata (p_ac3dec);
  72         return 1;
  73     }
  74
  75     /* compute downmix parameters
  76      * downmix to tow channels for now */
  77     p_ac3dec->dm_par.clev = 0.0;
  78     p_ac3dec->dm_par.slev = 0.0;
  79     p_ac3dec->dm_par.unit = 1.0;
  80     if (p_ac3dec->bsi.acmod & 0x1)    /* have center */
  81         p_ac3dec->dm_par.clev = cmixlev_lut[p_ac3dec->bsi.cmixlev];
  82
  83     if (p_ac3dec->bsi.acmod & 0x4)    /* have surround channels */
  84         p_ac3dec->dm_par.slev = smixlev_lut[p_ac3dec->bsi.surmixlev];
  85
  86     p_ac3dec->dm_par.unit /= 1.0 + p_ac3dec->dm_par.clev + p_ac3dec->dm_par.slev;
  87     p_ac3dec->dm_par.clev *= p_ac3dec->dm_par.unit;
  88     p_ac3dec->dm_par.slev *= p_ac3dec->dm_par.unit;
  89
  90     for (i = 0; i < 6; i++) {
  91         /* Initialize freq/time sample storage */
  92         memset(p_ac3dec->samples, 0, sizeof(float) * 256 *
  93                 (p_ac3dec->bsi.nfchans + p_ac3dec->bsi.lfeon));
  94
  95
  96         if( p_ac3thread->p_fifo->b_die || p_ac3thread->p_fifo->b_error )
  97         {
  98             return 1;
  99         }
 100
 101         if( parse_audblk( p_ac3dec, i ) )
 102         {
 103             intf_WarnMsg( 3, "ac3dec warning: error during audioblock" );
 104             parse_auxdata( p_ac3dec );
 105             return 1;
 106         }
 107
 108         if( p_ac3thread->p_fifo->b_die || p_ac3thread->p_fifo->b_error )
 109         {
 110             return 1;
 111         }
 112
 113         if( exponent_unpack( p_ac3dec ) )
 114         {
 115             intf_WarnMsg( 3, "ac3dec warning: error during unpack" );
 116             parse_auxdata( p_ac3dec );
 117             return 1;
 118         }
 119
 120         bit_allocate (p_ac3dec);
 121         mantissa_unpack (p_ac3dec);
 122
 123         if( p_ac3thread->p_fifo->b_die || p_ac3thread->p_fifo->b_error )
 124         {
 125             return 1;
 126         }
 127
 128         if  (p_ac3dec->bsi.acmod == 0x2)
 129         {
 130             rematrix (p_ac3dec);
 131         }
 132
 133         imdct (p_ac3dec, buffer);
 134
 135         buffer += 2 * 256;
 136     }
 137
 138     parse_auxdata (p_ac3dec);
 139
 140     return 0;
 141 }
 142