ac3_parse.c

vlc stand 0.1.99 ist sehr einfach

/*****************************************************************************
 * ac3_parse.c: ac3 parsing procedures
 *****************************************************************************
 * Copyright (C) 1999, 2000 VideoLAN
 *
 * Authors:
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
 *****************************************************************************/
#include "defs.h"

#include "int_types.h"
#include "ac3_decoder.h"
#include "ac3_internal.h"
#include "ac3_bit_stream.h"

/* Misc LUT */
static u16 nfchans[] = { 2, 1, 2, 3, 3, 4, 4, 5 };

struct frmsize_s {
    u16 bit_rate;
    u16 frm_size[3];
};

static struct frmsize_s frmsizecod_tbl[] = {
      { 32  ,{64   ,69   ,96   } },
      { 32  ,{64   ,70   ,96   } },
      { 40  ,{80   ,87   ,120  } },
      { 40  ,{80   ,88   ,120  } },
      { 48  ,{96   ,104  ,144  } },
      { 48  ,{96   ,105  ,144  } },
      { 56  ,{112  ,121  ,168  } },
      { 56  ,{112  ,122  ,168  } },
      { 64  ,{128  ,139  ,192  } },
      { 64  ,{128  ,140  ,192  } },
      { 80  ,{160  ,174  ,240  } },
      { 80  ,{160  ,175  ,240  } },
      { 96  ,{192  ,208  ,288  } },
      { 96  ,{192  ,209  ,288  } },
      { 112 ,{224  ,243  ,336  } },
      { 112 ,{224  ,244  ,336  } },
      { 128 ,{256  ,278  ,384  } },
      { 128 ,{256  ,279  ,384  } },
      { 160 ,{320  ,348  ,480  } },
      { 160 ,{320  ,349  ,480  } },
      { 192 ,{384  ,417  ,576  } },
      { 192 ,{384  ,418  ,576  } },
      { 224 ,{448  ,487  ,672  } },
      { 224 ,{448  ,488  ,672  } },
      { 256 ,{512  ,557  ,768  } },
      { 256 ,{512  ,558  ,768  } },
      { 320 ,{640  ,696  ,960  } },
      { 320 ,{640  ,697  ,960  } },
      { 384 ,{768  ,835  ,1152 } },
      { 384 ,{768  ,836  ,1152 } },
      { 448 ,{896  ,975  ,1344 } },
      { 448 ,{896  ,976  ,1344 } },
      { 512 ,{1024 ,1114 ,1536 } },
      { 512 ,{1024 ,1115 ,1536 } },
      { 576 ,{1152 ,1253 ,1728 } },
      { 576 ,{1152 ,1254 ,1728 } },
      { 640 ,{1280 ,1393 ,1920 } },
      { 640 ,{1280 ,1394 ,1920 } }};

static int fscod_tbl[] = {48000, 44100, 32000};

/* Parse a syncinfo structure */
int ac3_sync_frame (ac3dec_t * p_ac3dec, ac3_sync_info_t * p_sync_info) 
{
    int buf;

    p_ac3dec->bit_stream.total_bits_read = 0;
    p_ac3dec->bit_stream.i_available = 0;

    /* sync word - should be 0x0b77 */
    NeedBits (&(p_ac3dec->bit_stream), 16);
    buf =  p_ac3dec->bit_stream.buffer >> (32 - 16);
    DumpBits (&(p_ac3dec->bit_stream), 16);
    if (buf != 0x0b77)
	return 1;

    /* Get crc1 - we don't actually use this data though */
    NeedBits (&(p_ac3dec->bit_stream), 16);
    DumpBits (&(p_ac3dec->bit_stream), 16);

    /* Get the sampling rate */
    NeedBits (&(p_ac3dec->bit_stream), 2);
    p_ac3dec->syncinfo.fscod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
    DumpBits (&(p_ac3dec->bit_stream), 2);

    if (p_ac3dec->syncinfo.fscod >= 3)
	return 1;

    /* Get the frame size code */
    NeedBits (&(p_ac3dec->bit_stream), 6);
    p_ac3dec->syncinfo.frmsizecod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 6));
    DumpBits (&(p_ac3dec->bit_stream), 6);

    if (p_ac3dec->syncinfo.frmsizecod >= 38)
	return 1;

    p_sync_info->bit_rate = frmsizecod_tbl[p_ac3dec->syncinfo.frmsizecod].bit_rate;

    p_ac3dec->syncinfo.frame_size = frmsizecod_tbl[p_ac3dec->syncinfo.frmsizecod].frm_size[p_ac3dec->syncinfo.fscod];
    p_sync_info->frame_size = 2 * p_ac3dec->syncinfo.frame_size;

    p_sync_info->sample_rate = fscod_tbl[p_ac3dec->syncinfo.fscod];

    return 0;
}

/*
 * This routine fills a bsi struct from the AC3 stream
 */
int parse_bsi (ac3dec_t * p_ac3dec)
{
    u32 i;

    /* Check the AC-3 version number */
    NeedBits (&(p_ac3dec->bit_stream), 5);
    p_ac3dec->bsi.bsid = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 5));
    DumpBits (&(p_ac3dec->bit_stream), 5);

    if (p_ac3dec->bsi.bsid > 8)
	return 1;

    /* Get the audio service provided by the steram */
    NeedBits (&(p_ac3dec->bit_stream), 3);
    p_ac3dec->bsi.bsmod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 3));
    DumpBits (&(p_ac3dec->bit_stream), 3);

    /* Get the audio coding mode (ie how many channels)*/
    NeedBits (&(p_ac3dec->bit_stream), 3);
    p_ac3dec->bsi.acmod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 3));
    DumpBits (&(p_ac3dec->bit_stream), 3);
    /* Predecode the number of full bandwidth channels as we use this
     * number a lot */
    p_ac3dec->bsi.nfchans = nfchans[p_ac3dec->bsi.acmod];

    /* If it is in use, get the centre channel mix level */
    if ((p_ac3dec->bsi.acmod & 0x1) && (p_ac3dec->bsi.acmod != 0x1)) {
        NeedBits (&(p_ac3dec->bit_stream), 2);
        p_ac3dec->bsi.cmixlev = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
        DumpBits (&(p_ac3dec->bit_stream), 2);
    }

    /* If it is in use, get the surround channel mix level */
    if (p_ac3dec->bsi.acmod & 0x4) {
        NeedBits (&(p_ac3dec->bit_stream), 2);
        p_ac3dec->bsi.surmixlev = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
        DumpBits (&(p_ac3dec->bit_stream), 2);
    }

    /* Get the dolby surround mode if in 2/0 mode */
    if (p_ac3dec->bsi.acmod == 0x2) {
        NeedBits (&(p_ac3dec->bit_stream), 2);
        p_ac3dec->bsi.dsurmod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
        DumpBits (&(p_ac3dec->bit_stream), 2);
    }

    /* Is the low frequency effects channel on? */
    NeedBits (&(p_ac3dec->bit_stream), 1);
    p_ac3dec->bsi.lfeon = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));
    DumpBits (&(p_ac3dec->bit_stream), 1);

    /* Get the dialogue normalization level */
    NeedBits (&(p_ac3dec->bit_stream), 5);
    p_ac3dec->bsi.dialnorm = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 5));
    DumpBits (&(p_ac3dec->bit_stream), 5);

    /* Does compression gain exist? */
    NeedBits (&(p_ac3dec->bit_stream), 1);
    p_ac3dec->bsi.compre = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));
    DumpBits (&(p_ac3dec->bit_stream), 1);
    if (p_ac3dec->bsi.compre) {
        /* Get compression gain */
        NeedBits (&(p_ac3dec->bit_stream), 8);
        p_ac3dec->bsi.compr = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 8));
        DumpBits (&(p_ac3dec->bit_stream), 8);
    }

    /* Does language code exist? */
    NeedBits (&(p_ac3dec->bit_stream), 1);
    p_ac3dec->bsi.langcode = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));
    DumpBits (&(p_ac3dec->bit_stream), 1);
    if (p_ac3dec->bsi.langcode) {
        /* Get langauge code */
        NeedBits (&(p_ac3dec->bit_stream), 8);
        p_ac3dec->bsi.langcod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 8));
        DumpBits (&(p_ac3dec->bit_stream), 8);
    }

    /* Does audio production info exist? */
    NeedBits (&(p_ac3dec->bit_stream), 1);
    p_ac3dec->bsi.audprodie = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));
    DumpBits (&(p_ac3dec->bit_stream), 1);
    if (p_ac3dec->bsi.audprodie) {
        /* Get mix level */
        NeedBits (&(p_ac3dec->bit_stream), 5);
        p_ac3dec->bsi.mixlevel = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 5));
        DumpBits (&(p_ac3dec->bit_stream), 5);

        /* Get room type */
        NeedBits (&(p_ac3dec->bit_stream), 2);
        p_ac3dec->bsi.roomtyp = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
        DumpBits (&(p_ac3dec->bit_stream), 2);
    }

    /* If we're in dual mono mode then get some extra info */
    if (p_ac3dec->bsi.acmod ==0) {
        /* Get the dialogue normalization level two */
        NeedBits (&(p_ac3dec->bit_stream), 5);
        p_ac3dec->bsi.dialnorm2 = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 5));
        DumpBits (&(p_ac3dec->bit_stream), 5);

        /* Does compression gain two exist? */
        NeedBits (&(p_ac3dec->bit_stream), 1);
        p_ac3dec->bsi.compr2e = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));
        DumpBits (&(p_ac3dec->bit_stream), 1);
        if (p_ac3dec->bsi.compr2e) {
            /* Get compression gain two */
            NeedBits (&(p_ac3dec->bit_stream), 8);
            p_ac3dec->bsi.compr2 = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 8));
            DumpBits (&(p_ac3dec->bit_stream), 8);
        }

        /* Does language code two exist? */
        NeedBits (&(p_ac3dec->bit_stream), 1);
        p_ac3dec->bsi.langcod2e = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));
        DumpBits (&(p_ac3dec->bit_stream), 1);
        if (p_ac3dec->bsi.langcod2e) {
            /* Get langauge code two */
            NeedBits (&(p_ac3dec->bit_stream), 8);
            p_ac3dec->bsi.langcod2 = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 8));
            DumpBits (&(p_ac3dec->bit_stream), 8);
        }

        /* Does audio production info two exist? */
        NeedBits (&(p_ac3dec->bit_stream), 1);
        p_ac3dec->bsi.audprodi2e = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));
        DumpBits (&(p_ac3dec->bit_stream), 1);
        if (p_ac3dec->bsi.audprodi2e) {
            /* Get mix level two */
            NeedBits (&(p_ac3dec->bit_stream), 5);
            p_ac3dec->bsi.mixlevel2 = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 5));
            DumpBits (&(p_ac3dec->bit_stream), 5);

            /* Get room type two */
            NeedBits (&(p_ac3dec->bit_stream), 2);
            p_ac3dec->bsi.roomtyp2 = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
            DumpBits (&(p_ac3dec->bit_stream), 2);
        }
    }

    /* Get the copyright bit */
    NeedBits (&(p_ac3dec->bit_stream), 1);
    p_ac3dec->bsi.copyrightb = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));