ac3_parse.c

vlc stand 0.1.99 ist sehr einfach

	if ((!blknum) && (p_ac3dec->audblk.lfeexpstr == EXP_REUSE))
	    return 1;
    }

    /* Determine the bandwidths of all the fbw channels */
    for (i = 0; i < p_ac3dec->bsi.nfchans; i++) {
        u16 grp_size;

        if (p_ac3dec->audblk.chexpstr[i] != EXP_REUSE) {
            if (p_ac3dec->audblk.cplinu && p_ac3dec->audblk.chincpl[i]) {
                p_ac3dec->audblk.endmant[i] = p_ac3dec->audblk.cplstrtmant;
            } else {
                NeedBits (&(p_ac3dec->bit_stream), 6);
                p_ac3dec->audblk.chbwcod[i] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 6));
                DumpBits (&(p_ac3dec->bit_stream), 6);

		if (p_ac3dec->audblk.chbwcod[i] > 60)
		    return 1;

                p_ac3dec->audblk.endmant[i] = ((p_ac3dec->audblk.chbwcod[i] + 12) * 3) + 37;
            }

            /* Calculate the number of exponent groups to fetch */
            grp_size =  3 * (1 << (p_ac3dec->audblk.chexpstr[i] - 1));
            p_ac3dec->audblk.nchgrps[i] = (p_ac3dec->audblk.endmant[i] - 1 + (grp_size - 3)) / grp_size;
        }
    }

    /* Get the coupling exponents if they exist */
    if (p_ac3dec->audblk.cplinu && (p_ac3dec->audblk.cplexpstr != EXP_REUSE)) {
        NeedBits (&(p_ac3dec->bit_stream), 4);
        p_ac3dec->audblk.cplabsexp = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 4));
        DumpBits (&(p_ac3dec->bit_stream), 4);
        for (i=0; i< p_ac3dec->audblk.ncplgrps;i++) {
            NeedBits (&(p_ac3dec->bit_stream), 7);
            p_ac3dec->audblk.cplexps[i] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 7));
            DumpBits (&(p_ac3dec->bit_stream), 7);

	    if (p_ac3dec->audblk.cplexps[i] >= 125)
		return 1;
        }
    }

    /* Get the fwb channel exponents */
    for (i=0; i < p_ac3dec->bsi.nfchans; i++) {
        if (p_ac3dec->audblk.chexpstr[i] != EXP_REUSE) {
            NeedBits (&(p_ac3dec->bit_stream), 4);
            p_ac3dec->audblk.exps[i][0] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 4));
            DumpBits (&(p_ac3dec->bit_stream), 4);
            for (j=1; j<=p_ac3dec->audblk.nchgrps[i];j++) {
                NeedBits (&(p_ac3dec->bit_stream), 7);
                p_ac3dec->audblk.exps[i][j] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 7));
                DumpBits (&(p_ac3dec->bit_stream), 7);
		if (p_ac3dec->audblk.exps[i][j] >= 125)
		    return 1;
            }
            NeedBits (&(p_ac3dec->bit_stream), 2);
            p_ac3dec->audblk.gainrng[i] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
            DumpBits (&(p_ac3dec->bit_stream), 2);
        }
    }

    /* Get the lfe channel exponents */
    if (p_ac3dec->bsi.lfeon && (p_ac3dec->audblk.lfeexpstr != EXP_REUSE)) {
        NeedBits (&(p_ac3dec->bit_stream), 4);
        p_ac3dec->audblk.lfeexps[0] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 4));
        DumpBits (&(p_ac3dec->bit_stream), 4);
        NeedBits (&(p_ac3dec->bit_stream), 7);
        p_ac3dec->audblk.lfeexps[1] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 7));
        DumpBits (&(p_ac3dec->bit_stream), 7);
	if (p_ac3dec->audblk.lfeexps[1] >= 125)
	    return 1;
        NeedBits (&(p_ac3dec->bit_stream), 7);
        p_ac3dec->audblk.lfeexps[2] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 7));
        DumpBits (&(p_ac3dec->bit_stream), 7);
	if (p_ac3dec->audblk.lfeexps[2] >= 125)
	    return 1;
    }

    /* Get the parametric bit allocation parameters */
    NeedBits (&(p_ac3dec->bit_stream), 1);
    p_ac3dec->audblk.baie = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));
    DumpBits (&(p_ac3dec->bit_stream), 1);

    if ((!blknum) && (!p_ac3dec->audblk.baie))
	return 1;

    if (p_ac3dec->audblk.baie) {
        NeedBits (&(p_ac3dec->bit_stream), 2);
        p_ac3dec->audblk.sdcycod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
        DumpBits (&(p_ac3dec->bit_stream), 2);
        NeedBits (&(p_ac3dec->bit_stream), 2);
        p_ac3dec->audblk.fdcycod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
        DumpBits (&(p_ac3dec->bit_stream), 2);
        NeedBits (&(p_ac3dec->bit_stream), 2);
        p_ac3dec->audblk.sgaincod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
        DumpBits (&(p_ac3dec->bit_stream), 2);
        NeedBits (&(p_ac3dec->bit_stream), 2);
        p_ac3dec->audblk.dbpbcod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
        DumpBits (&(p_ac3dec->bit_stream), 2);
        NeedBits (&(p_ac3dec->bit_stream), 3);
        p_ac3dec->audblk.floorcod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 3));
        DumpBits (&(p_ac3dec->bit_stream), 3);
    }

    /* Get the SNR off set info if it exists */
    NeedBits (&(p_ac3dec->bit_stream), 1);
    p_ac3dec->audblk.snroffste = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));
    DumpBits (&(p_ac3dec->bit_stream), 1);
    if ((!blknum) && (!p_ac3dec->audblk.snroffste))
	return 1;

    if (p_ac3dec->audblk.snroffste) {
        NeedBits (&(p_ac3dec->bit_stream), 6);
        p_ac3dec->audblk.csnroffst = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 6));
        DumpBits (&(p_ac3dec->bit_stream), 6);

        if (p_ac3dec->audblk.cplinu) {
            NeedBits (&(p_ac3dec->bit_stream), 4);
            p_ac3dec->audblk.cplfsnroffst = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 4));
            DumpBits (&(p_ac3dec->bit_stream), 4);
            NeedBits (&(p_ac3dec->bit_stream), 3);
            p_ac3dec->audblk.cplfgaincod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 3));
            DumpBits (&(p_ac3dec->bit_stream), 3);
        }

        for (i = 0;i < p_ac3dec->bsi.nfchans; i++) {
            NeedBits (&(p_ac3dec->bit_stream), 4);
            p_ac3dec->audblk.fsnroffst[i] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 4));
            DumpBits (&(p_ac3dec->bit_stream), 4);
            NeedBits (&(p_ac3dec->bit_stream), 3);
            p_ac3dec->audblk.fgaincod[i] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 3));
            DumpBits (&(p_ac3dec->bit_stream), 3);
        }
        if (p_ac3dec->bsi.lfeon) {
            NeedBits (&(p_ac3dec->bit_stream), 4);
            p_ac3dec->audblk.lfefsnroffst = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 4));
            DumpBits (&(p_ac3dec->bit_stream), 4);
            NeedBits (&(p_ac3dec->bit_stream), 3);
            p_ac3dec->audblk.lfefgaincod = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 3));
            DumpBits (&(p_ac3dec->bit_stream), 3);
        }
    }

    /* Get coupling leakage info if it exists */
    if (p_ac3dec->audblk.cplinu) {
        NeedBits (&(p_ac3dec->bit_stream), 1);
        p_ac3dec->audblk.cplleake = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));
        DumpBits (&(p_ac3dec->bit_stream), 1);
	if ((!blknum) && (!p_ac3dec->audblk.cplleake))
	    return 1;

        if (p_ac3dec->audblk.cplleake) {
            NeedBits (&(p_ac3dec->bit_stream), 3);
            p_ac3dec->audblk.cplfleak = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 3));
            DumpBits (&(p_ac3dec->bit_stream), 3);
            NeedBits (&(p_ac3dec->bit_stream), 3);
            p_ac3dec->audblk.cplsleak = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 3));
            DumpBits (&(p_ac3dec->bit_stream), 3);
        }
    }

    /* Get the delta bit alloaction info */
    NeedBits (&(p_ac3dec->bit_stream), 1);
    p_ac3dec->audblk.deltbaie = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));
    DumpBits (&(p_ac3dec->bit_stream), 1);

    if (p_ac3dec->audblk.deltbaie) {
        if (p_ac3dec->audblk.cplinu) {
            NeedBits (&(p_ac3dec->bit_stream), 2);
            p_ac3dec->audblk.cpldeltbae = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
            DumpBits (&(p_ac3dec->bit_stream), 2);
	    if (p_ac3dec->audblk.cpldeltbae == 3)
		return 1;
        }

        for (i = 0;i < p_ac3dec->bsi.nfchans; i++) {
            NeedBits (&(p_ac3dec->bit_stream), 2);
            p_ac3dec->audblk.deltbae[i] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 2));
            DumpBits (&(p_ac3dec->bit_stream), 2);
	    if (p_ac3dec->audblk.deltbae[i] == 3)
		return 1;
        }

        if (p_ac3dec->audblk.cplinu && (p_ac3dec->audblk.cpldeltbae == DELTA_BIT_NEW)) {
            NeedBits (&(p_ac3dec->bit_stream), 3);
            p_ac3dec->audblk.cpldeltnseg = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 3));
            DumpBits (&(p_ac3dec->bit_stream), 3);
            for (i = 0;i < p_ac3dec->audblk.cpldeltnseg + 1; i++) {
                NeedBits (&(p_ac3dec->bit_stream), 5);
                p_ac3dec->audblk.cpldeltoffst[i] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 5));
                DumpBits (&(p_ac3dec->bit_stream), 5);
                NeedBits (&(p_ac3dec->bit_stream), 4);
                p_ac3dec->audblk.cpldeltlen[i] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 4));
                DumpBits (&(p_ac3dec->bit_stream), 4);
                NeedBits (&(p_ac3dec->bit_stream), 3);
                p_ac3dec->audblk.cpldeltba[i] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 3));
                DumpBits (&(p_ac3dec->bit_stream), 3);
            }
        }

        for (i = 0; i < p_ac3dec->bsi.nfchans; i++) {
            if (p_ac3dec->audblk.deltbae[i] == DELTA_BIT_NEW) {
                NeedBits (&(p_ac3dec->bit_stream), 3);
                p_ac3dec->audblk.deltnseg[i] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 3));
                DumpBits (&(p_ac3dec->bit_stream), 3);
//                if (p_ac3dec->audblk.deltnseg[i] >= 8)
//                    fprintf (stderr, "parse debug: p_ac3dec->audblk.deltnseg[%i] == %i\n", i, p_ac3dec->audblk.deltnseg[i]);
                for (j = 0; j < p_ac3dec->audblk.deltnseg[i] + 1; j++) {
                    NeedBits (&(p_ac3dec->bit_stream), 5);
                    p_ac3dec->audblk.deltoffst[i][j] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 5));
                    DumpBits (&(p_ac3dec->bit_stream), 5);
                    NeedBits (&(p_ac3dec->bit_stream), 4);
                    p_ac3dec->audblk.deltlen[i][j] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 4));
                    DumpBits (&(p_ac3dec->bit_stream), 4);
                    NeedBits (&(p_ac3dec->bit_stream), 3);
                    p_ac3dec->audblk.deltba[i][j] = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 3));
                    DumpBits (&(p_ac3dec->bit_stream), 3);
                }
            }
        }
    }

    /* Check to see if there's any dummy info to get */
    NeedBits (&(p_ac3dec->bit_stream), 1);
    p_ac3dec->audblk.skiple = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 1));
    DumpBits (&(p_ac3dec->bit_stream), 1);

    if (p_ac3dec->audblk.skiple) {
        NeedBits (&(p_ac3dec->bit_stream), 9);
        p_ac3dec->audblk.skipl = (u16)(p_ac3dec->bit_stream.buffer >> (32 - 9));
        DumpBits (&(p_ac3dec->bit_stream), 9);

        for (i = 0; i < p_ac3dec->audblk.skipl ; i++) {
            NeedBits (&(p_ac3dec->bit_stream), 8);
            DumpBits (&(p_ac3dec->bit_stream), 8);
        }
    }

    return 0;
}

void parse_auxdata (ac3dec_t * p_ac3dec)
{
    int i;
    int skip_length;

    skip_length = (p_ac3dec->syncinfo.frame_size * 16) - p_ac3dec->bit_stream.total_bits_read - 17 - 1;
//    fprintf (stderr, "parse debug: skip_length == %i\n", skip_length);

    for (i = 0; i < skip_length; i++) {
        NeedBits (&(p_ac3dec->bit_stream), 1);
        DumpBits (&(p_ac3dec->bit_stream), 1);
    }

    /* get the auxdata exists bit */
    NeedBits (&(p_ac3dec->bit_stream), 1);
    DumpBits (&(p_ac3dec->bit_stream), 1);

    /* Skip the CRC reserved bit */
    NeedBits (&(p_ac3dec->bit_stream), 1);
    DumpBits (&(p_ac3dec->bit_stream), 1);

    /* Get the crc */
    NeedBits (&(p_ac3dec->bit_stream), 16);
    DumpBits (&(p_ac3dec->bit_stream), 16);
}