vp3.c

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.10平台上编译为嵌入式图形界面操作系统。

        s->first_coded_y_fragment,
        s->last_coded_y_fragment,
        s->first_coded_c_fragment,
        s->last_coded_c_fragment);

    return 0;
}

/*
 * This function unpacks all the coding mode data for individual macroblocks
 * from the bitstream.
 */
static int unpack_modes(Vp3DecodeContext *s, GetBitContext *gb)
{
    int i, j, k;
    int scheme;
    int current_macroblock;
    int current_fragment;
    int coding_mode;

    debug_vp3("  vp3: unpacking encoding modes\n");

    if (s->keyframe) {
        debug_vp3("    keyframe-- all blocks are coded as INTRA\n");

        for (i = 0; i < s->fragment_count; i++)
            s->all_fragments[i].coding_method = MODE_INTRA;

    } else {

        /* fetch the mode coding scheme for this frame */
        scheme = get_bits(gb, 3);
        debug_modes("    using mode alphabet %d\n", scheme);

        /* is it a custom coding scheme? */
        if (scheme == 0) {
            debug_modes("    custom mode alphabet ahead:\n");
            for (i = 0; i < 8; i++)
                ModeAlphabet[scheme][get_bits(gb, 3)] = i;
        }

        for (i = 0; i < 8; i++)
            debug_modes("      mode[%d][%d] = %d\n", scheme, i, 
                ModeAlphabet[scheme][i]);

        /* iterate through all of the macroblocks that contain 1 or more
         * coded fragments */
        for (i = 0; i < s->u_superblock_start; i++) {

            for (j = 0; j < 4; j++) {
                current_macroblock = s->superblock_macroblocks[i * 4 + j];
                if ((current_macroblock == -1) ||
                    (s->macroblock_coding[current_macroblock] == MODE_COPY))
                    continue;
                if (current_macroblock >= s->macroblock_count) {
                    av_log(s->avctx, AV_LOG_ERROR, "  vp3:unpack_modes(): bad macroblock number (%d >= %d)\n",
                        current_macroblock, s->macroblock_count);
                    return 1;
                }

                /* mode 7 means get 3 bits for each coding mode */
                if (scheme == 7)
                    coding_mode = get_bits(gb, 3);
                else
                    coding_mode = ModeAlphabet[scheme][get_mode_code(gb)];

                s->macroblock_coding[current_macroblock] = coding_mode;
                for (k = 0; k < 6; k++) {
                    current_fragment = 
                        s->macroblock_fragments[current_macroblock * 6 + k];
                    if (current_fragment == -1)
                        continue;
                    if (current_fragment >= s->fragment_count) {
                        av_log(s->avctx, AV_LOG_ERROR, "  vp3:unpack_modes(): bad fragment number (%d >= %d)\n",
                            current_fragment, s->fragment_count);
                        return 1;
                    }
                    if (s->all_fragments[current_fragment].coding_method != 
                        MODE_COPY)
                        s->all_fragments[current_fragment].coding_method =
                            coding_mode;
                }

                debug_modes("    coding method for macroblock starting @ fragment %d = %d\n",
                    s->macroblock_fragments[current_macroblock * 6], coding_mode);
            }
        }
    }

    return 0;
}

/*
 * This function unpacks all the motion vectors for the individual
 * macroblocks from the bitstream.
 */
static int unpack_vectors(Vp3DecodeContext *s, GetBitContext *gb)
{
    int i, j, k;
    int coding_mode;
    int motion_x[6];
    int motion_y[6];
    int last_motion_x = 0;
    int last_motion_y = 0;
    int prior_last_motion_x = 0;
    int prior_last_motion_y = 0;
    int current_macroblock;
    int current_fragment;

    debug_vp3("  vp3: unpacking motion vectors\n");
    if (s->keyframe) {

        debug_vp3("    keyframe-- there are no motion vectors\n");

    } else {

        memset(motion_x, 0, 6 * sizeof(int));
        memset(motion_y, 0, 6 * sizeof(int));

        /* coding mode 0 is the VLC scheme; 1 is the fixed code scheme */
        coding_mode = get_bits(gb, 1);
        debug_vectors("    using %s scheme for unpacking motion vectors\n",
            (coding_mode == 0) ? "VLC" : "fixed-length");

        /* iterate through all of the macroblocks that contain 1 or more
         * coded fragments */
        for (i = 0; i < s->u_superblock_start; i++) {

            for (j = 0; j < 4; j++) {
                current_macroblock = s->superblock_macroblocks[i * 4 + j];
                if ((current_macroblock == -1) ||
                    (s->macroblock_coding[current_macroblock] == MODE_COPY))
                    continue;
                if (current_macroblock >= s->macroblock_count) {
                    av_log(s->avctx, AV_LOG_ERROR, "  vp3:unpack_vectors(): bad macroblock number (%d >= %d)\n",
                        current_macroblock, s->macroblock_count);
                    return 1;
                }

                current_fragment = s->macroblock_fragments[current_macroblock * 6];
                if (current_fragment >= s->fragment_count) {
                    av_log(s->avctx, AV_LOG_ERROR, "  vp3:unpack_vectors(): bad fragment number (%d >= %d\n",
                        current_fragment, s->fragment_count);
                    return 1;
                }
                switch (s->macroblock_coding[current_macroblock]) {

                case MODE_INTER_PLUS_MV:
                case MODE_GOLDEN_MV:
                    /* all 6 fragments use the same motion vector */
                    if (coding_mode == 0) {
                        motion_x[0] = get_motion_vector_vlc(gb);
                        motion_y[0] = get_motion_vector_vlc(gb);
                    } else {
                        motion_x[0] = get_motion_vector_fixed(gb);
                        motion_y[0] = get_motion_vector_fixed(gb);
                    }
                    for (k = 1; k < 6; k++) {
                        motion_x[k] = motion_x[0];
                        motion_y[k] = motion_y[0];
                    }

                    /* vector maintenance, only on MODE_INTER_PLUS_MV */
                    if (s->macroblock_coding[current_macroblock] ==
                        MODE_INTER_PLUS_MV) {
                        prior_last_motion_x = last_motion_x;
                        prior_last_motion_y = last_motion_y;
                        last_motion_x = motion_x[0];
                        last_motion_y = motion_y[0];
                    }
                    break;

                case MODE_INTER_FOURMV:
                    /* fetch 4 vectors from the bitstream, one for each
                     * Y fragment, then average for the C fragment vectors */
                    motion_x[4] = motion_y[4] = 0;
                    for (k = 0; k < 4; k++) {
                        if (coding_mode == 0) {
                            motion_x[k] = get_motion_vector_vlc(gb);
                            motion_y[k] = get_motion_vector_vlc(gb);
                        } else {
                            motion_x[k] = get_motion_vector_fixed(gb);
                            motion_y[k] = get_motion_vector_fixed(gb);
                        }
                        motion_x[4] += motion_x[k];
                        motion_y[4] += motion_y[k];
                    }

                    if (motion_x[4] >= 0) 
                        motion_x[4] = (motion_x[4] + 2) / 4;
                    else
                        motion_x[4] = (motion_x[4] - 2) / 4;
                    motion_x[5] = motion_x[4];

                    if (motion_y[4] >= 0) 
                        motion_y[4] = (motion_y[4] + 2) / 4;
                    else
                        motion_y[4] = (motion_y[4] - 2) / 4;
                    motion_y[5] = motion_y[4];

                    /* vector maintenance; vector[3] is treated as the
                     * last vector in this case */
                    prior_last_motion_x = last_motion_x;
                    prior_last_motion_y = last_motion_y;
                    last_motion_x = motion_x[3];
                    last_motion_y = motion_y[3];
                    break;

                case MODE_INTER_LAST_MV:
                    /* all 6 fragments use the last motion vector */
                    motion_x[0] = last_motion_x;
                    motion_y[0] = last_motion_y;
                    for (k = 1; k < 6; k++) {
                        motion_x[k] = motion_x[0];
                        motion_y[k] = motion_y[0];
                    }

                    /* no vector maintenance (last vector remains the
                     * last vector) */
                    break;

                case MODE_INTER_PRIOR_LAST:
                    /* all 6 fragments use the motion vector prior to the
                     * last motion vector */
                    motion_x[0] = prior_last_motion_x;
                    motion_y[0] = prior_last_motion_y;
                    for (k = 1; k < 6; k++) {
                        motion_x[k] = motion_x[0];
                        motion_y[k] = motion_y[0];
                    }

                    /* vector maintenance */
                    prior_last_motion_x = last_motion_x;
                    prior_last_motion_y = last_motion_y;
                    last_motion_x = motion_x[0];
                    last_motion_y = motion_y[0];
                    break;

                default:
                    /* covers intra, inter without MV, golden without MV */
                    memset(motion_x, 0, 6 * sizeof(int));
                    memset(motion_y, 0, 6 * sizeof(int));

                    /* no vector maintenance */
                    break;
                }

                /* assign the motion vectors to the correct fragments */
                debug_vectors("    vectors for macroblock starting @ fragment %d (coding method %d):\n",
                    current_fragment,
                    s->macroblock_coding[current_macroblock]);
                for (k = 0; k < 6; k++) {
                    current_fragment = 
                        s->macroblock_fragments[current_macroblock * 6 + k];
                    if (current_fragment == -1)
                        continue;
                    if (current_fragment >= s->fragment_count) {
                        av_log(s->avctx, AV_LOG_ERROR, "  vp3:unpack_vectors(): bad fragment number (%d >= %d)\n",
                            current_fragment, s->fragment_count);
                        return 1;
                    }
                    s->all_fragments[current_fragment].motion_x = motion_x[k];
                    s->all_fragments[current_fragment].motion_y = motion_y[k];
                    debug_vectors("    vector %d: fragment %d = (%d, %d)\n",
                        k, current_fragment, motion_x[k], motion_y[k]);
                }
            }
        }
    }

    return 0;
}

/* 
 * This function is called by unpack_dct_coeffs() to extract the VLCs from
 * the bitstream. The VLCs encode tokens which are used to unpack DCT
 * data. This function unpacks all the VLCs for either the Y plane or both
 * C planes, and is called for DC coefficients or different AC coefficient
 * levels (since different coefficient types require different VLC tables.
 *
 * This function returns a residual eob run. E.g, if a particular token gave
 * instructions to EOB the next 5 fragments and there were only 2 fragments
 * left in the current fragment range, 3 would be returned so that it could
 * be passed into the next call to this same function.
 */
static int unpack_vlcs(Vp3DecodeContext *s, GetBitContext *gb,
                        VLC *table, int coeff_index,
                        int first_fragment, int last_fragment,
                        int eob_run)
{
    int i;
    int token;
    int zero_run;
    DCTELEM coeff;
    Vp3Fragment *fragment;

    if ((first_fragment >= s->fragment_count) ||
        (last_fragment >= s->fragment_count)) {

        av_log(s->avctx, AV_LOG_ERROR, "  vp3:unpack_vlcs(): bad fragment number (%d -> %d ?)\n",
            first_fragment, last_fragment);
        return 0;
    }

    for (i = first_fragment; i <= last_fragment; i++) {

        fragment = &s->all_fragments[s->coded_fragment_list[i]];
        if (fragment->coeff_count > coeff_index)
            continue;

        if (!eob_run) {
            /* decode a VLC into a token */
            token = get_vlc2(gb, table->table, 5, 3);
            debug_vlc(" token = %2d, ", token);
            /* use the token to get a zero run, a coefficient, and an eob run */
            unpack_token(gb, token, &zero_run, &coeff, &eob_run);
        }

        if (!eob_run) {
            fragment->coeff_count += zero_run;
            if (fragment->coeff_count < 64)
                fragment->coeffs[fragment->coeff_count++] = coeff;
            debug_vlc(" fragment %d coeff = %d\n",
                s->coded_fragment_list[i], fragment->coeffs[coeff_index]);
        } else {
            fragment->last_coeff = fragment->coeff_count;
            fragment->coeff_count = 64;
            debug_vlc(" fragment %d eob with %d coefficients\n", 
                s->coded_fragment_list[i], fragment->last_coeff);
            eob_run--;
        }
    }

    return eob_run;
}

/*
 * This function unpacks all of the DCT coefficient data from the
 * bitstream.
 */
static int unpack_dct_coeffs(Vp3DecodeContext *s, GetBitContext *gb)
{
    int i;
    int dc_y_table;
    int dc_c_table;
    int ac_y_table;
    int ac_c_table;
    int residual_eob_run = 0;

    /* fetch the DC table indices */
    dc_y_table = get_bits(gb, 4);
    dc_c_table = get_bits(gb, 4);

    /* unpack the Y plane DC coefficients */
    debug_vp3("  vp3: unpacking Y plane DC coefficients using table %d\n",
        dc_y_table);
    residual_eob_run = unpack_vlcs(s, gb, &s->dc_vlc[dc_y_table], 0, 
        s->first_coded_y_fragment, s->last_coded_y_fragment, residual_eob_run);

    /* unpack the C plane DC coefficients */
    debug_vp3("  vp3: unpacking C plane DC coefficients using table %d\n",
        dc_c_table);
    residual_eob_run = unpack_vlcs(s, gb, &s->dc_vlc[dc_c_table], 0,
        s->first_coded_c_fragment, s->last_coded_c_fragment, residual_eob_run);

    /* fetch the AC table indices */
    ac_y_table = get_bits(gb, 4);
    ac_c_table = get_bits(gb, 4);

    /* unpack the group 1 AC coefficients (coeffs 1-5) */
    for (i = 1; i <= 5; i++) {

        debug_vp3("  vp3: unpacking level %d Y plane AC coefficients using table %d\n",
            i, ac_y_table);
        residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_1[ac_y_table], i, 
            s->first_coded_y_fragment, s->last_coded_y_fragment, residual_eob_run);

        debug_vp3("  vp3: unpacking level %d C plane AC coefficients using table %d\n",
            i, ac_c_table);
        residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_1[ac_c_table], i, 
            s->first_coded_c_fragment, s->last_coded_c_fragment, residual_eob_run);
    }

    /* unpack the group 2 AC coefficients (coeffs 6-14) */
    for (i = 6; i <= 14; i++) {

        debug_vp3("  vp3: unpacking level %d Y plane AC coefficients using table %d\n",
            i, ac_y_table);
        residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_2[ac_y_table], i, 
            s->first_coded_y_fragment, s->last_coded_y_fragment, residual_eob_run);

        debug_vp3("  vp3: unpacking level %d C plane AC coefficients using table %d\n",
            i, ac_c_table);
        residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_2[ac_c_table], i, 
            s->first_coded_c_fragment, s->last_coded_c_fragment, residual_eob_run);
    }

    /* unpack the group 3 AC coefficients (coeffs 15-27) */
    for (i = 15; i <= 27; i++) {

        debug_vp3("  vp3: unpacking level %d Y plane AC coefficients using table %d\n",
            i, ac_y_table);
        residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_3[ac_y_table], i, 
            s->first_coded_y_fragment, s->last_coded_y_fragment, residual_eob_run