FFmpeg/libavcodec/vc1_block.c

/*
 * VC-1 and WMV3 decoder
 * Copyright (c) 2011 Mashiat Sarker Shakkhar
 * Copyright (c) 2006-2007 Konstantin Shishkov
 * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, Michael Niedermayer
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * VC-1 and WMV3 block decoding routines
 */

#include "avcodec.h"
#include "mpegutils.h"
#include "mpegvideo.h"
#include "mpegvideodec.h"
#include "msmpeg4_vc1_data.h"
#include "unary.h"
#include "vc1.h"
#include "vc1_pred.h"
#include "vc1acdata.h"
#include "vc1data.h"

// offset tables for interlaced picture MVDATA decoding
static const uint8_t offset_table[2][9] = {
    {  0,  1,  2,  4,  8, 16, 32,  64, 128 },
    {  0,  1,  3,  7, 15, 31, 63, 127, 255 },
};

// mapping table for internal block representation
static const int block_map[6] = {0, 2, 1, 3, 4, 5};

/***********************************************************************/
/**
 * @name VC-1 Bitplane decoding
 * @see 8.7, p56
 * @{
 */


static inline void init_block_index(VC1Context *v)
{
    MpegEncContext *s = &v->s;
    ff_init_block_index(s);
    if (v->field_mode && !(v->second_field ^ v->tff)) {
        s->dest[0] += s->current_picture_ptr->f->linesize[0];
        s->dest[1] += s->current_picture_ptr->f->linesize[1];
        s->dest[2] += s->current_picture_ptr->f->linesize[2];
    }
}

static inline void update_block_index(MpegEncContext *s)
{
    /* VC1 is always 420 except when using AV_CODEC_FLAG_GRAY
     * (or a HWAccel). Shall we inline this value? */
    ff_update_block_index(s, 8, 0, s->chroma_x_shift);
}

/** @} */ //Bitplane group

static void vc1_put_blocks_clamped(VC1Context *v, int put_signed)
{
    MpegEncContext *s = &v->s;
    uint8_t *dest;
    int block_count = CONFIG_GRAY && (s->avctx->flags & AV_CODEC_FLAG_GRAY) ? 4 : 6;
    int fieldtx = 0;
    int i;

    /* The put pixels loop is one MB row and one MB column behind the decoding
     * loop because we can only put pixels when overlap filtering is done. For
     * interlaced frame pictures, however, the put pixels loop is only one
     * column behind the decoding loop as interlaced frame pictures only need
     * horizontal overlap filtering. */
    if (!s->first_slice_line && v->fcm != ILACE_FRAME) {
        if (s->mb_x) {
            for (i = 0; i < block_count; i++) {
                if (i > 3 ? v->mb_type[0][s->block_index[i] - s->block_wrap[i] - 1] :
                            v->mb_type[0][s->block_index[i] - 2 * s->block_wrap[i] - 2]) {
                    dest = s->dest[0] + ((i & 2) - 4) * 4 * s->linesize + ((i & 1) - 2) * 8;
                    if (put_signed)
                        s->idsp.put_signed_pixels_clamped(v->block[v->topleft_blk_idx][block_map[i]],
                                                          i > 3 ? s->dest[i - 3] - 8 * s->uvlinesize - 8 : dest,
                                                          i > 3 ? s->uvlinesize : s->linesize);
                    else
                        s->idsp.put_pixels_clamped(v->block[v->topleft_blk_idx][block_map[i]],
                                                   i > 3 ? s->dest[i - 3] - 8 * s->uvlinesize - 8 : dest,
                                                   i > 3 ? s->uvlinesize : s->linesize);
                }
            }
        }
        if (s->mb_x == v->end_mb_x - 1) {
            for (i = 0; i < block_count; i++) {
                if (i > 3 ? v->mb_type[0][s->block_index[i] - s->block_wrap[i]] :
                            v->mb_type[0][s->block_index[i] - 2 * s->block_wrap[i]]) {
                    dest = s->dest[0] + ((i & 2) - 4) * 4 * s->linesize + (i & 1) * 8;
                    if (put_signed)
                        s->idsp.put_signed_pixels_clamped(v->block[v->top_blk_idx][block_map[i]],
                                                          i > 3 ? s->dest[i - 3] - 8 * s->uvlinesize : dest,
                                                          i > 3 ? s->uvlinesize : s->linesize);
                    else
                        s->idsp.put_pixels_clamped(v->block[v->top_blk_idx][block_map[i]],
                                                   i > 3 ? s->dest[i - 3] - 8 * s->uvlinesize : dest,
                                                   i > 3 ? s->uvlinesize : s->linesize);
                }
            }
        }
    }
    if (s->mb_y == s->end_mb_y - 1 || v->fcm == ILACE_FRAME) {
        if (s->mb_x) {
            if (v->fcm == ILACE_FRAME)
                fieldtx = v->fieldtx_plane[s->mb_y * s->mb_stride + s->mb_x - 1];
            for (i = 0; i < block_count; i++) {
                if (i > 3 ? v->mb_type[0][s->block_index[i] - 1] :
                            v->mb_type[0][s->block_index[i] - 2]) {
                    if (fieldtx)
                        dest = s->dest[0] + ((i & 2) >> 1) * s->linesize + ((i & 1) - 2) * 8;
                    else
                        dest = s->dest[0] + (i & 2) * 4 * s->linesize + ((i & 1) - 2) * 8;
                    if (put_signed)
                        s->idsp.put_signed_pixels_clamped(v->block[v->left_blk_idx][block_map[i]],
                                                          i > 3 ? s->dest[i - 3] - 8 : dest,
                                                          i > 3 ? s->uvlinesize : s->linesize << fieldtx);
                    else
                        s->idsp.put_pixels_clamped(v->block[v->left_blk_idx][block_map[i]],
                                                   i > 3 ? s->dest[i - 3] - 8 : dest,
                                                   i > 3 ? s->uvlinesize : s->linesize << fieldtx);
                }
            }
        }
        if (s->mb_x == v->end_mb_x - 1) {
            if (v->fcm == ILACE_FRAME)
                fieldtx = v->fieldtx_plane[s->mb_y * s->mb_stride + s->mb_x];
            for (i = 0; i < block_count; i++) {
                if (v->mb_type[0][s->block_index[i]]) {
                    if (fieldtx)
                        dest = s->dest[0] + ((i & 2) >> 1) * s->linesize + (i & 1) * 8;
                    else
                        dest = s->dest[0] + (i & 2) * 4 * s->linesize + (i & 1) * 8;
                    if (put_signed)
                        s->idsp.put_signed_pixels_clamped(v->block[v->cur_blk_idx][block_map[i]],
                                                          i > 3 ? s->dest[i - 3] : dest,
                                                          i > 3 ? s->uvlinesize : s->linesize << fieldtx);
                    else
                        s->idsp.put_pixels_clamped(v->block[v->cur_blk_idx][block_map[i]],
                                                   i > 3 ? s->dest[i - 3] : dest,
                                                   i > 3 ? s->uvlinesize : s->linesize << fieldtx);
                }
            }
        }
    }
}

#define inc_blk_idx(idx) do { \
        idx++; \
        if (idx >= v->n_allocated_blks) \
            idx = 0; \
    } while (0)

/***********************************************************************/
/**
 * @name VC-1 Block-level functions
 * @see 7.1.4, p91 and 8.1.1.7, p(1)04
 * @{
 */

/**
 * @def GET_MQUANT
 * @brief Get macroblock-level quantizer scale
 */
#define GET_MQUANT()                                           \
    if (v->dquantfrm) {                                        \
        int edges = 0;                                         \
        if (v->dqprofile == DQPROFILE_ALL_MBS) {               \
            if (v->dqbilevel) {                                \
                mquant = (get_bits1(gb)) ? -v->altpq : v->pq;  \
            } else {                                           \
                mqdiff = get_bits(gb, 3);                      \
                if (mqdiff != 7)                               \
                    mquant = -v->pq - mqdiff;                  \
                else                                           \
                    mquant = -get_bits(gb, 5);                 \
            }                                                  \
        }                                                      \
        if (v->dqprofile == DQPROFILE_SINGLE_EDGE)             \
            edges = 1 << v->dqsbedge;                          \
        else if (v->dqprofile == DQPROFILE_DOUBLE_EDGES)       \
            edges = (3 << v->dqsbedge) % 15;                   \
        else if (v->dqprofile == DQPROFILE_FOUR_EDGES)         \
            edges = 15;                                        \
        if ((edges&1) && !s->mb_x)                             \
            mquant = -v->altpq;                                \
        if ((edges&2) && !s->mb_y)                             \
            mquant = -v->altpq;                                \
        if ((edges&4) && s->mb_x == (s->mb_width - 1))         \
            mquant = -v->altpq;                                \
        if ((edges&8) &&                                       \
            s->mb_y == ((s->mb_height >> v->field_mode) - 1))  \
            mquant = -v->altpq;                                \
        if (!mquant || mquant > 31 || mquant < -31) {                          \
            av_log(v->s.avctx, AV_LOG_ERROR,                   \
                   "Overriding invalid mquant %d\n", mquant);  \
            mquant = 1;                                        \
        }                                                      \
    }

/**
 * @def GET_MVDATA(_dmv_x, _dmv_y)
 * @brief Get MV differentials
 * @see MVDATA decoding from 8.3.5.2, p(1)20
 * @param _dmv_x Horizontal differential for decoded MV
 * @param _dmv_y Vertical differential for decoded MV
 */
#define GET_MVDATA(_dmv_x, _dmv_y)                                      \
    index = 1 + get_vlc2(gb, ff_vc1_mv_diff_vlc[s->mv_table_index],     \
                         VC1_MV_DIFF_VLC_BITS, 2);                      \
    if (index > 36) {                                                   \
        mb_has_coeffs = 1;                                              \
        index -= 37;                                                    \
    } else                                                              \
        mb_has_coeffs = 0;                                              \
    s->mb_intra = 0;                                                    \
    if (!index) {                                                       \
        _dmv_x = _dmv_y = 0;                                            \
    } else if (index == 35) {                                           \
        _dmv_x = get_bits(gb, v->k_x - 1 + s->quarter_sample);          \
        _dmv_y = get_bits(gb, v->k_y - 1 + s->quarter_sample);          \
    } else if (index == 36) {                                           \
        _dmv_x = 0;                                                     \
        _dmv_y = 0;                                                     \
        s->mb_intra = 1;                                                \
    } else {                                                            \
        index1 = index % 6;                                             \
        _dmv_x = offset_table[1][index1];                               \
        val = size_table[index1] - (!s->quarter_sample && index1 == 5); \
        if (val > 0) {                                                  \
            val = get_bits(gb, val);                                    \
            sign = 0 - (val & 1);                                       \
            _dmv_x = (sign ^ ((val >> 1) + _dmv_x)) - sign;             \
        }                                                               \
                                                                        \
        index1 = index / 6;                                             \
        _dmv_y = offset_table[1][index1];                               \
        val = size_table[index1] - (!s->quarter_sample && index1 == 5); \
        if (val > 0) {                                                  \
            val = get_bits(gb, val);                                    \
            sign = 0 - (val & 1);                                       \
            _dmv_y = (sign ^ ((val >> 1) + _dmv_y)) - sign;             \
        }                                                               \
    }

static av_always_inline void get_mvdata_interlaced(VC1Context *v, int *dmv_x,
                                                   int *dmv_y, int *pred_flag)
{
    int index, index1;
    int extend_x, extend_y;
    GetBitContext *gb = &v->s.gb;
    int bits, esc;
    int val, sign;

    if (v->numref) {
        bits = VC1_2REF_MVDATA_VLC_BITS;
        esc  = 125;
    } else {
        bits = VC1_1REF_MVDATA_VLC_BITS;
        esc  = 71;
    }
    extend_x = v->dmvrange & 1;
    extend_y = (v->dmvrange >> 1) & 1;
    index = get_vlc2(gb, v->imv_vlc, bits, 3);
    if (index == esc) {
        *dmv_x = get_bits(gb, v->k_x);
        *dmv_y = get_bits(gb, v->k_y);
        if (v->numref) {
            if (pred_flag)
                *pred_flag = *dmv_y & 1;
            *dmv_y = (*dmv_y + (*dmv_y & 1)) >> 1;
        }
    }
    else {
        av_assert0(index < esc);
        index1 = (index + 1) % 9;
        if (index1 != 0) {
            val    = get_bits(gb, index1 + extend_x);
            sign   = 0 - (val & 1);
            *dmv_x = (sign ^ ((val >> 1) + offset_table[extend_x][index1])) - sign;
        } else
            *dmv_x = 0;
        index1 = (index + 1) / 9;
        if (index1 > v->numref) {
            val    = get_bits(gb, (index1 >> v->numref) + extend_y);
            sign   = 0 - (val & 1);
            *dmv_y = (sign ^ ((val >> 1) + offset_table[extend_y][index1 >> v->numref])) - sign;
        } else
            *dmv_y = 0;
        if (v->numref && pred_flag)
            *pred_flag = index1 & 1;
    }
}

/** Reconstruct motion vector for B-frame and do motion compensation
 */
static inline void vc1_b_mc(VC1Context *v, int dmv_x[2], int dmv_y[2],
                            int direct, int mode)
{
    if (direct) {
        ff_vc1_mc_1mv(v, 0);
        ff_vc1_interp_mc(v);
        return;
    }
    if (mode == BMV_TYPE_INTERPOLATED) {
        ff_vc1_mc_1mv(v, 0);
        ff_vc1_interp_mc(v);
        return;
    }

    ff_vc1_mc_1mv(v, (mode == BMV_TYPE_BACKWARD));
}

/** Get predicted DC value for I-frames only
 * prediction dir: left=0, top=1
 * @param s MpegEncContext
 * @param overlap flag indicating that overlap filtering is used
 * @param pq integer part of picture quantizer
 * @param[in] n block index in the current MB
 * @param dc_val_ptr Pointer to DC predictor
 * @param dir_ptr Prediction direction for use in AC prediction
 */
static inline int vc1_i_pred_dc(MpegEncContext *s, int overlap, int pq, int n,
                                int16_t **dc_val_ptr, int *dir_ptr)
{
    int a, b, c, wrap, pred, scale;
    int16_t *dc_val;
    static const uint16_t dcpred[32] = {
        -1, 1024,  512,  341,  256,  205,  171,  146,  128,
             114,  102,   93,   85,   79,   73,   68,   64,
              60,   57,   54,   51,   49,   47,   45,   43,
              41,   39,   38,   37,   35,   34,   33
    };

    /* find prediction - wmv3_dc_scale always used here in fact */
    if (n < 4) scale = s->y_dc_scale;
    else       scale = s->c_dc_scale;

    wrap   = s->block_wrap[n];
    dc_val = s->dc_val[0] + s->block_index[n];

    /* B A
     * C X
     */
    c = dc_val[ - 1];
    b = dc_val[ - 1 - wrap];
    a = dc_val[ - wrap];

    if (pq < 9 || !overlap) {
        /* Set outer values */
        if (s->first_slice_line && (n != 2 && n != 3))
            b = a = dcpred[scale];
        if (s->mb_x == 0 && (n != 1 && n != 3))
            b = c = dcpred[scale];
    } else {
        /* Set outer values */
        if (s->first_slice_line && (n != 2 && n != 3))
            b = a = 0;
        if (s->mb_x == 0 && (n != 1 && n != 3))
            b = c = 0;
    }

    if (abs(a - b) <= abs(b - c)) {
        pred     = c;
        *dir_ptr = 1; // left
    } else {
        pred     = a;
        *dir_ptr = 0; // top
    }

    /* update predictor */
    *dc_val_ptr = &dc_val[0];
    return pred;
}


/** Get predicted DC value
 * prediction dir: left=0, top=1
 * @param s MpegEncContext
 * @param overlap flag indicating that overlap filtering is used
 * @param pq integer part of picture quantizer
 * @param[in] n block index in the current MB
 * @param a_avail flag indicating top block availability
 * @param c_avail flag indicating left block availability
 * @param dc_val_ptr Pointer to DC predictor
 * @param dir_ptr Prediction direction for use in AC prediction
 */
static inline int ff_vc1_pred_dc(MpegEncContext *s, int overlap, int pq, int n,
                              int a_avail, int c_avail,
                              int16_t **dc_val_ptr, int *dir_ptr)
{
    int a, b, c, wrap, pred;
    int16_t *dc_val;
    int mb_pos = s->mb_x + s->mb_y * s->mb_stride;
    int q1, q2 = 0;
    int dqscale_index;

    /* scale predictors if needed */
    q1 = FFABS(s->current_picture.qscale_table[mb_pos]);
    dqscale_index = s->y_dc_scale_table[q1] - 1;
    if (dqscale_index < 0)
        return 0;

    wrap = s->block_wrap[n];
    dc_val = s->dc_val[0] + s->block_index[n];

    /* B A
     * C X
     */
    c = dc_val[ - 1];
    b = dc_val[ - 1 - wrap];
    a = dc_val[ - wrap];

    if (c_avail && (n != 1 && n != 3)) {
        q2 = FFABS(s->current_picture.qscale_table[mb_pos - 1]);
        if (q2 && q2 != q1)
            c = (int)((unsigned)c * s->y_dc_scale_table[q2] * ff_vc1_dqscale[dqscale_index] + 0x20000) >> 18;
    }
    if (a_avail && (n != 2 && n != 3)) {
        q2 = FFABS(s->current_picture.qscale_table[mb_pos - s->mb_stride]);
        if (q2 && q2 != q1)
            a = (int)((unsigned)a * s->y_dc_scale_table[q2] * ff_vc1_dqscale[dqscale_index] + 0x20000) >> 18;
    }
    if (a_avail && c_avail && (n != 3)) {
        int off = mb_pos;
        if (n != 1)
            off--;
        if (n != 2)
            off -= s->mb_stride;
        q2 = FFABS(s->current_picture.qscale_table[off]);
        if (q2 && q2 != q1)
            b = (int)((unsigned)b * s->y_dc_scale_table[q2] * ff_vc1_dqscale[dqscale_index] + 0x20000) >> 18;
    }

    if (c_avail && (!a_avail || abs(a - b) <= abs(b - c))) {
        pred     = c;
        *dir_ptr = 1; // left
    } else if (a_avail) {
        pred     = a;
        *dir_ptr = 0; // top
    } else {
        pred     = 0;
        *dir_ptr = 1; // left
    }

    /* update predictor */
    *dc_val_ptr = &dc_val[0];
    return pred;
}

/** @} */ // Block group

/**
 * @name VC1 Macroblock-level functions in Simple/Main Profiles
 * @see 7.1.4, p91 and 8.1.1.7, p(1)04
 * @{
 */

static inline int vc1_coded_block_pred(MpegEncContext * s, int n,
                                       uint8_t **coded_block_ptr)
{
    int xy, wrap, pred, a, b, c;

    xy   = s->block_index[n];
    wrap = s->b8_stride;

    /* B C
     * A X
     */
    a = s->coded_block[xy - 1       ];
    b = s->coded_block[xy - 1 - wrap];
    c = s->coded_block[xy     - wrap];

    if (b == c) {
        pred = a;
    } else {
        pred = c;
    }

    /* store value */
    *coded_block_ptr = &s->coded_block[xy];

    return pred;
}

/**
 * Decode one AC coefficient
 * @param v The VC1 context
 * @param last Last coefficient
 * @param skip How much zero coefficients to skip
 * @param value Decoded AC coefficient value
 * @param codingset set of VLC to decode data
 * @see 8.1.3.4
 */
static int vc1_decode_ac_coeff(VC1Context *v, int *last, int *skip,
                                int *value, int codingset)
{
    GetBitContext *gb = &v->s.gb;
    int index, run, level, lst, sign;

    index = get_vlc2(gb, ff_vc1_ac_coeff_table[codingset], AC_VLC_BITS, 3);
    if (index < 0)
        return index;
    if (index != ff_vc1_ac_sizes[codingset] - 1) {
        run   = vc1_index_decode_table[codingset][index][0];
        level = vc1_index_decode_table[codingset][index][1];
        lst   = index >= vc1_last_decode_table[codingset] || get_bits_left(gb) < 0;
        sign  = get_bits1(gb);
    } else {
        int escape = decode210(gb);
        if (escape != 2) {
            index = get_vlc2(gb, ff_vc1_ac_coeff_table[codingset], AC_VLC_BITS, 3);
            if (index >= ff_vc1_ac_sizes[codingset] - 1U)
                return AVERROR_INVALIDDATA;
            run   = vc1_index_decode_table[codingset][index][0];
            level = vc1_index_decode_table[codingset][index][1];
            lst   = index >= vc1_last_decode_table[codingset];
            if (escape == 0) {
                if (lst)
                    level += vc1_last_delta_level_table[codingset][run];
                else
                    level += vc1_delta_level_table[codingset][run];
            } else {
                if (lst)
                    run += vc1_last_delta_run_table[codingset][level] + 1;
                else
                    run += vc1_delta_run_table[codingset][level] + 1;
            }
            sign = get_bits1(gb);
        } else {
            lst = get_bits1(gb);
            if (v->s.esc3_level_length == 0) {
                if (v->pq < 8 || v->dquantfrm) { // table 59
                    v->s.esc3_level_length = get_bits(gb, 3);
                    if (!v->s.esc3_level_length)
                        v->s.esc3_level_length = get_bits(gb, 2) + 8;
                } else { // table 60
                    v->s.esc3_level_length = get_unary(gb, 1, 6) + 2;
                }
                v->s.esc3_run_length = 3 + get_bits(gb, 2);
            }
            run   = get_bits(gb, v->s.esc3_run_length);
            sign  = get_bits1(gb);
            level = get_bits(gb, v->s.esc3_level_length);
        }
    }

    *last  = lst;
    *skip  = run;
    *value = (level ^ -sign) + sign;

    return 0;
}

/** Decode intra block in intra frames - should be faster than decode_intra_block
 * @param v VC1Context
 * @param block block to decode
 * @param[in] n subblock index
 * @param coded are AC coeffs present or not
 * @param codingset set of VLC to decode data
 */
static int vc1_decode_i_block(VC1Context *v, int16_t block[64], int n,
                              int coded, int codingset)
{
    GetBitContext *gb = &v->s.gb;
    MpegEncContext *s = &v->s;
    int dc_pred_dir = 0; /* Direction of the DC prediction used */
    int i;
    int16_t *dc_val;
    int16_t *ac_val, *ac_val2;
    int dcdiff, scale;

    /* Get DC differential */
    dcdiff = get_vlc2(&s->gb, ff_msmp4_dc_vlc[s->dc_table_index][n >= 4],
                      MSMP4_DC_VLC_BITS, 3);
    if (dcdiff) {
        const int m = (v->pq == 1 || v->pq == 2) ? 3 - v->pq : 0;
        if (dcdiff == 119 /* ESC index value */) {
            dcdiff = get_bits(gb, 8 + m);
        } else {
            if (m)
                dcdiff = (dcdiff << m) + get_bits(gb, m) - ((1 << m) - 1);
        }
        if (get_bits1(gb))
            dcdiff = -dcdiff;
    }

    /* Prediction */
    dcdiff += vc1_i_pred_dc(&v->s, v->overlap, v->pq, n, &dc_val, &dc_pred_dir);
    *dc_val = dcdiff;

    /* Store the quantized DC coeff, used for prediction */
    if (n < 4)
        scale = s->y_dc_scale;
    else
        scale = s->c_dc_scale;
    block[0] = dcdiff * scale;

    ac_val  = s->ac_val[0][s->block_index[n]];
    ac_val2 = ac_val;
    if (dc_pred_dir) // left
        ac_val -= 16;
    else // top
        ac_val -= 16 * s->block_wrap[n];

    scale = v->pq * 2 + v->halfpq;

    //AC Decoding
    i = !!coded;

    if (coded) {
        int last = 0, skip, value;
        const uint8_t *zz_table;
        int k;

        if (v->s.ac_pred) {
            if (!dc_pred_dir)
                zz_table = v->zz_8x8[2];
            else
                zz_table = v->zz_8x8[3];
        } else
            zz_table = v->zz_8x8[1];

        while (!last) {
            int ret = vc1_decode_ac_coeff(v, &last, &skip, &value, codingset);
            if (ret < 0)
                return ret;
            i += skip;
            if (i > 63)
                break;
            block[zz_table[i++]] = value;
        }

        /* apply AC prediction if needed */
        if (s->ac_pred) {
            int sh;
            if (dc_pred_dir) { // left
                sh = v->left_blk_sh;
            } else { // top
                sh = v->top_blk_sh;
                ac_val += 8;
            }
            for (k = 1; k < 8; k++)
                block[k << sh] += ac_val[k];
        }
        /* save AC coeffs for further prediction */
        for (k = 1; k < 8; k++) {
            ac_val2[k]     = block[k << v->left_blk_sh];
            ac_val2[k + 8] = block[k << v->top_blk_sh];
        }

        /* scale AC coeffs */
        for (k = 1; k < 64; k++)
            if (block[k]) {
                block[k] *= scale;
                if (!v->pquantizer)
                    block[k] += (block[k] < 0) ? -v->pq : v->pq;
            }

    } else {
        int k;

        memset(ac_val2, 0, 16 * 2);

        /* apply AC prediction if needed */
        if (s->ac_pred) {
            int sh;
            if (dc_pred_dir) { //left
                sh = v->left_blk_sh;
            } else { // top
                sh = v->top_blk_sh;
                ac_val  += 8;
                ac_val2 += 8;
            }
            memcpy(ac_val2, ac_val, 8 * 2);
            for (k = 1; k < 8; k++) {
                block[k << sh] = ac_val[k] * scale;
                if (!v->pquantizer && block[k << sh])
                    block[k << sh] += (block[k << sh] < 0) ? -v->pq : v->pq;
            }
        }
    }
    if (s->ac_pred) i = 63;
    s->block_last_index[n] = i;

    return 0;
}

/** Decode intra block in intra frames - should be faster than decode_intra_block
 * @param v VC1Context
 * @param block block to decode
 * @param[in] n subblock number
 * @param coded are AC coeffs present or not
 * @param codingset set of VLC to decode data
 * @param mquant quantizer value for this macroblock
 */
static int vc1_decode_i_block_adv(VC1Context *v, int16_t block[64], int n,
                                  int coded, int codingset, int mquant)
{
    GetBitContext *gb = &v->s.gb;
    MpegEncContext *s = &v->s;
    int dc_pred_dir = 0; /* Direction of the DC prediction used */
    int i;
    int16_t *dc_val = NULL;
    int16_t *ac_val, *ac_val2;
    int dcdiff;
    int a_avail = v->a_avail, c_avail = v->c_avail;
    int use_pred = s->ac_pred;
    int scale;
    int q1, q2 = 0;
    int mb_pos = s->mb_x + s->mb_y * s->mb_stride;
    int quant = FFABS(mquant);

    /* Get DC differential */
    dcdiff = get_vlc2(&s->gb, ff_msmp4_dc_vlc[s->dc_table_index][n >= 4],
                      MSMP4_DC_VLC_BITS, 3);
    if (dcdiff) {
        const int m = (quant == 1 || quant == 2) ? 3 - quant : 0;
        if (dcdiff == 119 /* ESC index value */) {
            dcdiff = get_bits(gb, 8 + m);
        } else {
            if (m)
                dcdiff = (dcdiff << m) + get_bits(gb, m) - ((1 << m) - 1);
        }
        if (get_bits1(gb))
            dcdiff = -dcdiff;
    }

    /* Prediction */
    dcdiff += ff_vc1_pred_dc(&v->s, v->overlap, quant, n, v->a_avail, v->c_avail, &dc_val, &dc_pred_dir);
    *dc_val = dcdiff;

    /* Store the quantized DC coeff, used for prediction */
    if (n < 4)
        scale = s->y_dc_scale;
    else
        scale = s->c_dc_scale;
    block[0] = dcdiff * scale;

    /* check if AC is needed at all */
    if (!a_avail && !c_avail)
        use_pred = 0;

    scale = quant * 2 + ((mquant < 0) ? 0 : v->halfpq);

    ac_val  = s->ac_val[0][s->block_index[n]];
    ac_val2 = ac_val;
    if (dc_pred_dir) // left
        ac_val -= 16;
    else // top
        ac_val -= 16 * s->block_wrap[n];

    q1 = s->current_picture.qscale_table[mb_pos];
    if (n == 3)
        q2 = q1;
    else if (dc_pred_dir) {
        if (n == 1)
            q2 = q1;
        else if (c_avail && mb_pos)
            q2 = s->current_picture.qscale_table[mb_pos - 1];
    } else {
        if (n == 2)
            q2 = q1;
        else if (a_avail && mb_pos >= s->mb_stride)
            q2 = s->current_picture.qscale_table[mb_pos - s->mb_stride];
    }

    //AC Decoding
    i = 1;

    if (coded) {
        int last = 0, skip, value;
        const uint8_t *zz_table;
        int k;

        if (v->s.ac_pred) {
            if (!use_pred && v->fcm == ILACE_FRAME) {
                zz_table = v->zzi_8x8;
            } else {
                if (!dc_pred_dir) // top
                    zz_table = v->zz_8x8[2];
                else // left
                    zz_table = v->zz_8x8[3];
            }
        } else {
            if (v->fcm != ILACE_FRAME)
                zz_table = v->zz_8x8[1];
            else
                zz_table = v->zzi_8x8;
        }

        while (!last) {
            int ret = vc1_decode_ac_coeff(v, &last, &skip, &value, codingset);
            if (ret < 0)
                return ret;
            i += skip;
            if (i > 63)
                break;
            block[zz_table[i++]] = value;
        }

        /* apply AC prediction if needed */
        if (use_pred) {
            int sh;
            if (dc_pred_dir) { // left
                sh = v->left_blk_sh;
            } else { // top
                sh = v->top_blk_sh;
                ac_val += 8;
            }
            /* scale predictors if needed*/
            q1 = FFABS(q1) * 2 + ((q1 < 0) ? 0 : v->halfpq) - 1;
            if (q1 < 1)
                return AVERROR_INVALIDDATA;
            if (q2)
                q2 = FFABS(q2) * 2 + ((q2 < 0) ? 0 : v->halfpq) - 1;
            if (q2 && q1 != q2) {
                for (k = 1; k < 8; k++)
                    block[k << sh] += (int)(ac_val[k] * (unsigned)q2 * ff_vc1_dqscale[q1 - 1] + 0x20000) >> 18;
            } else {
                for (k = 1; k < 8; k++)
                    block[k << sh] += ac_val[k];
            }
        }
        /* save AC coeffs for further prediction */
        for (k = 1; k < 8; k++) {
            ac_val2[k    ] = block[k << v->left_blk_sh];
            ac_val2[k + 8] = block[k << v->top_blk_sh];
        }

        /* scale AC coeffs */
        for (k = 1; k < 64; k++)
            if (block[k]) {
                block[k] *= scale;
                if (!v->pquantizer)
                    block[k] += (block[k] < 0) ? -quant : quant;
            }

    } else { // no AC coeffs
        int k;

        memset(ac_val2, 0, 16 * 2);

        /* apply AC prediction if needed */
        if (use_pred) {
            int sh;
            if (dc_pred_dir) { // left
                sh = v->left_blk_sh;
            } else { // top
                sh = v->top_blk_sh;
                ac_val  += 8;
                ac_val2 += 8;
            }
            memcpy(ac_val2, ac_val, 8 * 2);
            q1 = FFABS(q1) * 2 + ((q1 < 0) ? 0 : v->halfpq) - 1;
            if (q1 < 1)
                return AVERROR_INVALIDDATA;
            if (q2)
                q2 = FFABS(q2) * 2 + ((q2 < 0) ? 0 : v->halfpq) - 1;
            if (q2 && q1 != q2) {
                for (k = 1; k < 8; k++)
                    ac_val2[k] = (int)(ac_val2[k] * q2 * (unsigned)ff_vc1_dqscale[q1 - 1] + 0x20000) >> 18;
            }
            for (k = 1; k < 8; k++) {
                block[k << sh] = ac_val2[k] * scale;
                if (!v->pquantizer && block[k << sh])
                    block[k << sh] += (block[k << sh] < 0) ? -quant : quant;
            }
        }
    }
    if (use_pred) i = 63;
    s->block_last_index[n] = i;

    return 0;
}

/** Decode intra block in inter frames - more generic version than vc1_decode_i_block
 * @param v VC1Context
 * @param block block to decode
 * @param[in] n subblock index
 * @param coded are AC coeffs present or not
 * @param mquant block quantizer
 * @param codingset set of VLC to decode data
 */
static int vc1_decode_intra_block(VC1Context *v, int16_t block[64], int n,
                                  int coded, int mquant, int codingset)
{
    GetBitContext *gb = &v->s.gb;
    MpegEncContext *s = &v->s;
    int dc_pred_dir = 0; /* Direction of the DC prediction used */
    int i;
    int16_t *dc_val = NULL;
    int16_t *ac_val, *ac_val2;
    int dcdiff;
    int mb_pos = s->mb_x + s->mb_y * s->mb_stride;
    int a_avail = v->a_avail, c_avail = v->c_avail;
    int use_pred = s->ac_pred;
    int scale;
    int q1, q2 = 0;
    int quant = FFABS(mquant);

    s->bdsp.clear_block(block);

    /* XXX: Guard against dumb values of mquant */
    quant = av_clip_uintp2(quant, 5);

    /* Set DC scale - y and c use the same */
    s->y_dc_scale = s->y_dc_scale_table[quant];
    s->c_dc_scale = s->c_dc_scale_table[quant];

    /* Get DC differential */
    dcdiff = get_vlc2(&s->gb, ff_msmp4_dc_vlc[s->dc_table_index][n >= 4],
                      MSMP4_DC_VLC_BITS, 3);
    if (dcdiff) {
        const int m = (quant == 1 || quant == 2) ? 3 - quant : 0;
        if (dcdiff == 119 /* ESC index value */) {
            dcdiff = get_bits(gb, 8 + m);
        } else {
            if (m)
                dcdiff = (dcdiff << m) + get_bits(gb, m) - ((1 << m) - 1);
        }
        if (get_bits1(gb))
            dcdiff = -dcdiff;
    }

    /* Prediction */
    dcdiff += ff_vc1_pred_dc(&v->s, v->overlap, quant, n, a_avail, c_avail, &dc_val, &dc_pred_dir);
    *dc_val = dcdiff;

    /* Store the quantized DC coeff, used for prediction */

    if (n < 4) {
        block[0] = dcdiff * s->y_dc_scale;
    } else {
        block[0] = dcdiff * s->c_dc_scale;
    }

    //AC Decoding
    i = 1;

    /* check if AC is needed at all and adjust direction if needed */
    if (!a_avail) dc_pred_dir = 1;
    if (!c_avail) dc_pred_dir = 0;
    if (!a_avail && !c_avail) use_pred = 0;
    ac_val = s->ac_val[0][s->block_index[n]];
    ac_val2 = ac_val;

    scale = quant * 2 + ((mquant < 0) ? 0 : v->halfpq);

    if (dc_pred_dir) //left
        ac_val -= 16;
    else //top
        ac_val -= 16 * s->block_wrap[n];

    q1 = s->current_picture.qscale_table[mb_pos];
    if (dc_pred_dir && c_avail && mb_pos)
        q2 = s->current_picture.qscale_table[mb_pos - 1];
    if (!dc_pred_dir && a_avail && mb_pos >= s->mb_stride)
        q2 = s->current_picture.qscale_table[mb_pos - s->mb_stride];
    if (dc_pred_dir && n == 1)
        q2 = q1;
    if (!dc_pred_dir && n == 2)
        q2 = q1;
    if (n == 3) q2 = q1;

    if (coded) {
        int last = 0, skip, value;
        int k;

        while (!last) {
            int ret = vc1_decode_ac_coeff(v, &last, &skip, &value, codingset);
            if (ret < 0)
                return ret;
            i += skip;
            if (i > 63)
                break;
            if (v->fcm == PROGRESSIVE)
                block[v->zz_8x8[0][i++]] = value;
            else {
                if (use_pred && (v->fcm == ILACE_FRAME)) {
                    if (!dc_pred_dir) // top
                        block[v->zz_8x8[2][i++]] = value;
                    else // left
                        block[v->zz_8x8[3][i++]] = value;
                } else {
                    block[v->zzi_8x8[i++]] = value;
                }
            }
        }

        /* apply AC prediction if needed */
        if (use_pred) {
            /* scale predictors if needed*/
            q1 = FFABS(q1) * 2 + ((q1 < 0) ? 0 : v->halfpq) - 1;
            if (q1 < 1)
                return AVERROR_INVALIDDATA;
            if (q2)
                q2 = FFABS(q2) * 2 + ((q2 < 0) ? 0 : v->halfpq) - 1;
            if (q2 && q1 != q2) {
                if (dc_pred_dir) { // left
                    for (k = 1; k < 8; k++)
                        block[k << v->left_blk_sh] += (int)(ac_val[k] * q2 * (unsigned)ff_vc1_dqscale[q1 - 1] + 0x20000) >> 18;
                } else { //top
                    for (k = 1; k < 8; k++)
                        block[k << v->top_blk_sh] += (int)(ac_val[k + 8] * q2 * (unsigned)ff_vc1_dqscale[q1 - 1] + 0x20000) >> 18;
                }
            } else {
                if (dc_pred_dir) { // left
                    for (k = 1; k < 8; k++)
                        block[k << v->left_blk_sh] += ac_val[k];
                } else { // top
                    for (k = 1; k < 8; k++)
                        block[k << v->top_blk_sh] += ac_val[k + 8];
                }
            }
        }
        /* save AC coeffs for further prediction */
        for (k = 1; k < 8; k++) {
            ac_val2[k    ] = block[k << v->left_blk_sh];
            ac_val2[k + 8] = block[k << v->top_blk_sh];
        }

        /* scale AC coeffs */
        for (k = 1; k < 64; k++)
            if (block[k]) {
                block[k] *= scale;
                if (!v->pquantizer)
                    block[k] += (block[k] < 0) ? -quant : quant;
            }

        if (use_pred) i = 63;
    } else { // no AC coeffs
        int k;

        memset(ac_val2, 0, 16 * 2);
        if (dc_pred_dir) { // left
            if (use_pred) {
                memcpy(ac_val2, ac_val, 8 * 2);
                q1 = FFABS(q1) * 2 + ((q1 < 0) ? 0 : v->halfpq) - 1;
                if (q1 < 1)
                    return AVERROR_INVALIDDATA;
                if (q2)
                    q2 = FFABS(q2) * 2 + ((q2 < 0) ? 0 : v->halfpq) - 1;
                if (q2 && q1 != q2) {
                    for (k = 1; k < 8; k++)
                        ac_val2[k] = (int)(ac_val2[k] * (unsigned)q2 * ff_vc1_dqscale[q1 - 1] + 0x20000) >> 18;
                }
            }
        } else { // top
            if (use_pred) {
                memcpy(ac_val2 + 8, ac_val + 8, 8 * 2);
                q1 = FFABS(q1) * 2 + ((q1 < 0) ? 0 : v->halfpq) - 1;
                if (q1 < 1)
                    return AVERROR_INVALIDDATA;
                if (q2)
                    q2 = FFABS(q2) * 2 + ((q2 < 0) ? 0 : v->halfpq) - 1;
                if (q2 && q1 != q2) {
                    for (k = 1; k < 8; k++)
                        ac_val2[k + 8] = (int)(ac_val2[k + 8] * (unsigned)q2 * ff_vc1_dqscale[q1 - 1] + 0x20000) >> 18;
                }
            }
        }

        /* apply AC prediction if needed */
        if (use_pred) {
            if (dc_pred_dir) { // left
                for (k = 1; k < 8; k++) {
                    block[k << v->left_blk_sh] = ac_val2[k] * scale;
                    if (!v->pquantizer && block[k << v->left_blk_sh])
                        block[k << v->left_blk_sh] += (block[k << v->left_blk_sh] < 0) ? -quant : quant;
                }
            } else { // top
                for (k = 1; k < 8; k++) {
                    block[k << v->top_blk_sh] = ac_val2[k + 8] * scale;
                    if (!v->pquantizer && block[k << v->top_blk_sh])
                        block[k << v->top_blk_sh] += (block[k << v->top_blk_sh] < 0) ? -quant : quant;
                }
            }
            i = 63;
        }
    }
    s->block_last_index[n] = i;

    return 0;
}

/** Decode P block
 */
static int vc1_decode_p_block(VC1Context *v, int16_t block[64], int n,
                              int mquant, int ttmb, int first_block,
                              uint8_t *dst, int linesize, int skip_block,
                              int *ttmb_out)
{
    MpegEncContext *s = &v->s;
    GetBitContext *gb = &s->gb;
    int i, j;
    int subblkpat = 0;
    int scale, off, idx, last, skip, value;
    int ttblk = ttmb & 7;
    int pat = 0;
    int quant = FFABS(mquant);

    s->bdsp.clear_block(block);

    if (ttmb == -1) {
        ttblk = ff_vc1_ttblk_to_tt[v->tt_index][get_vlc2(gb, ff_vc1_ttblk_vlc[v->tt_index], VC1_TTBLK_VLC_BITS, 1)];
    }
    if (ttblk == TT_4X4) {
        subblkpat = ~(get_vlc2(gb, ff_vc1_subblkpat_vlc[v->tt_index], VC1_SUBBLKPAT_VLC_BITS, 1) + 1);
    }
    if ((ttblk != TT_8X8 && ttblk != TT_4X4)
        && ((v->ttmbf || (ttmb != -1 && (ttmb & 8) && !first_block))
            || (!v->res_rtm_flag && !first_block))) {
        subblkpat = decode012(gb);
        if (subblkpat)
            subblkpat ^= 3; // swap decoded pattern bits
        if (ttblk == TT_8X4_TOP || ttblk == TT_8X4_BOTTOM)
            ttblk = TT_8X4;
        if (ttblk == TT_4X8_RIGHT || ttblk == TT_4X8_LEFT)
            ttblk = TT_4X8;
    }
    scale = quant * 2 + ((mquant < 0) ? 0 : v->halfpq);

    // convert transforms like 8X4_TOP to generic TT and SUBBLKPAT
    if (ttblk == TT_8X4_TOP || ttblk == TT_8X4_BOTTOM) {
        subblkpat = 2 - (ttblk == TT_8X4_TOP);
        ttblk     = TT_8X4;
    }
    if (ttblk == TT_4X8_RIGHT || ttblk == TT_4X8_LEFT) {
        subblkpat = 2 - (ttblk == TT_4X8_LEFT);
        ttblk     = TT_4X8;
    }
    switch (ttblk) {
    case TT_8X8:
        pat  = 0xF;
        i    = 0;
        last = 0;
        while (!last) {
            int ret = vc1_decode_ac_coeff(v, &last, &skip, &value, v->codingset2);
            if (ret < 0)
                return ret;
            i += skip;
            if (i > 63)
                break;
            if (!v->fcm)
                idx = v->zz_8x8[0][i++];
            else
                idx = v->zzi_8x8[i++];
            block[idx] = value * scale;
            if (!v->pquantizer)
                block[idx] += (block[idx] < 0) ? -quant : quant;
        }
        if (!skip_block) {
            if (i == 1)
                v->vc1dsp.vc1_inv_trans_8x8_dc(dst, linesize, block);
            else {
                v->vc1dsp.vc1_inv_trans_8x8(block);
                s->idsp.add_pixels_clamped(block, dst, linesize);
            }
        }
        break;
    case TT_4X4:
        pat = ~subblkpat & 0xF;
        for (j = 0; j < 4; j++) {
            last = subblkpat & (1 << (3 - j));
            i    = 0;
            off  = (j & 1) * 4 + (j & 2) * 16;
            while (!last) {
                int ret = vc1_decode_ac_coeff(v, &last, &skip, &value, v->codingset2);
                if (ret < 0)
                    return ret;
                i += skip;
                if (i > 15)
                    break;
                if (!v->fcm)
                    idx = ff_vc1_simple_progressive_4x4_zz[i++];
                else
                    idx = ff_vc1_adv_interlaced_4x4_zz[i++];
                block[idx + off] = value * scale;
                if (!v->pquantizer)
                    block[idx + off] += (block[idx + off] < 0) ? -quant : quant;
            }
            if (!(subblkpat & (1 << (3 - j))) && !skip_block) {
                if (i == 1)
                    v->vc1dsp.vc1_inv_trans_4x4_dc(dst + (j & 1) * 4 + (j & 2) * 2 * linesize, linesize, block + off);
                else
                    v->vc1dsp.vc1_inv_trans_4x4(dst + (j & 1) * 4 + (j & 2) *  2 * linesize, linesize, block + off);
            }
        }
        break;
    case TT_8X4:
        pat = ~((subblkpat & 2) * 6 + (subblkpat & 1) * 3) & 0xF;
        for (j = 0; j < 2; j++) {
            last = subblkpat & (1 << (1 - j));
            i    = 0;
            off  = j * 32;
            while (!last) {
                int ret = vc1_decode_ac_coeff(v, &last, &skip, &value, v->codingset2);
                if (ret < 0)
                    return ret;
                i += skip;
                if (i > 31)
                    break;
                if (!v->fcm)
                    idx = v->zz_8x4[i++] + off;
                else
                    idx = ff_vc1_adv_interlaced_8x4_zz[i++] + off;
                block[idx] = value * scale;
                if (!v->pquantizer)
                    block[idx] += (block[idx] < 0) ? -quant : quant;
            }
            if (!(subblkpat & (1 << (1 - j))) && !skip_block) {
                if (i == 1)
                    v->vc1dsp.vc1_inv_trans_8x4_dc(dst + j * 4 * linesize, linesize, block + off);
                else
                    v->vc1dsp.vc1_inv_trans_8x4(dst + j * 4 * linesize, linesize, block + off);
            }
        }
        break;
    case TT_4X8:
        pat = ~(subblkpat * 5) & 0xF;
        for (j = 0; j < 2; j++) {
            last = subblkpat & (1 << (1 - j));
            i    = 0;
            off  = j * 4;
            while (!last) {
                int ret = vc1_decode_ac_coeff(v, &last, &skip, &value, v->codingset2);
                if (ret < 0)
                    return ret;
                i += skip;
                if (i > 31)
                    break;
                if (!v->fcm)
                    idx = v->zz_4x8[i++] + off;
                else
                    idx = ff_vc1_adv_interlaced_4x8_zz[i++] + off;
                block[idx] = value * scale;
                if (!v->pquantizer)
                    block[idx] += (block[idx] < 0) ? -quant : quant;
            }
            if (!(subblkpat & (1 << (1 - j))) && !skip_block) {
                if (i == 1)
                    v->vc1dsp.vc1_inv_trans_4x8_dc(dst + j * 4, linesize, block + off);
                else
                    v->vc1dsp.vc1_inv_trans_4x8(dst + j*4, linesize, block + off);
            }
        }
        break;
    }
    if (ttmb_out)
        *ttmb_out |= ttblk << (n * 4);
    return pat;
}

/** @} */ // Macroblock group

static const uint8_t size_table[6] = { 0, 2, 3, 4,  5,  8 };

/** Decode one P-frame MB
 */
static int vc1_decode_p_mb(VC1Context *v)
{
    MpegEncContext *s = &v->s;
    GetBitContext *gb = &s->gb;
    int i, j;
    int mb_pos = s->mb_x + s->mb_y * s->mb_stride;
    int cbp; /* cbp decoding stuff */
    int mqdiff, mquant; /* MB quantization */
    int ttmb = v->ttfrm; /* MB Transform type */

    int mb_has_coeffs = 1; /* last_flag */
    int dmv_x, dmv_y; /* Differential MV components */
    int index, index1; /* LUT indexes */
    int val, sign; /* temp values */
    int first_block = 1;
    int dst_idx, off;
    int skipped, fourmv;
    int block_cbp = 0, pat, block_tt = 0, block_intra = 0;

    mquant = v->pq; /* lossy initialization */

    if (v->mv_type_is_raw)
        fourmv = get_bits1(gb);
    else
        fourmv = v->mv_type_mb_plane[mb_pos];
    if (v->skip_is_raw)
        skipped = get_bits1(gb);
    else
        skipped = v->s.mbskip_table[mb_pos];

    if (!fourmv) { /* 1MV mode */
        if (!skipped) {
            GET_MVDATA(dmv_x, dmv_y);

            if (s->mb_intra) {
                s->current_picture.motion_val[1][s->block_index[0]][0] = 0;
                s->current_picture.motion_val[1][s->block_index[0]][1] = 0;
            }
            s->current_picture.mb_type[mb_pos] = s->mb_intra ? MB_TYPE_INTRA : MB_TYPE_16x16;
            ff_vc1_pred_mv(v, 0, dmv_x, dmv_y, 1, v->range_x, v->range_y, v->mb_type[0], 0, 0);

            /* FIXME Set DC val for inter block ? */
            if (s->mb_intra && !mb_has_coeffs) {
                GET_MQUANT();
                s->ac_pred = get_bits1(gb);
                cbp        = 0;
            } else if (mb_has_coeffs) {
                if (s->mb_intra)
                    s->ac_pred = get_bits1(gb);
                cbp = get_vlc2(&v->s.gb, v->cbpcy_vlc, VC1_CBPCY_P_VLC_BITS, 2);
                GET_MQUANT();
            } else {
                mquant = v->pq;
                cbp    = 0;
            }
            s->current_picture.qscale_table[mb_pos] = mquant;

            if (!v->ttmbf && !s->mb_intra && mb_has_coeffs)
                ttmb = get_vlc2(gb, ff_vc1_ttmb_vlc[v->tt_index],
                                VC1_TTMB_VLC_BITS, 2);
            if (!s->mb_intra) ff_vc1_mc_1mv(v, 0);
            dst_idx = 0;
            for (i = 0; i < 6; i++) {
                s->dc_val[0][s->block_index[i]] = 0;
                dst_idx += i >> 2;
                val = ((cbp >> (5 - i)) & 1);
                off = (i & 4) ? 0 : ((i & 1) * 8 + (i & 2) * 4 * s->linesize);
                v->mb_type[0][s->block_index[i]] = s->mb_intra;
                if (s->mb_intra) {
                    /* check if prediction blocks A and C are available */
                    v->a_avail = v->c_avail = 0;
                    if (i == 2 || i == 3 || !s->first_slice_line)
                        v->a_avail = v->mb_type[0][s->block_index[i] - s->block_wrap[i]];
                    if (i == 1 || i == 3 || s->mb_x)
                        v->c_avail = v->mb_type[0][s->block_index[i] - 1];

                    vc1_decode_intra_block(v, v->block[v->cur_blk_idx][block_map[i]], i, val, mquant,
                                           (i & 4) ? v->codingset2 : v->codingset);
                    if (CONFIG_GRAY && (i > 3) && (s->avctx->flags & AV_CODEC_FLAG_GRAY))
                        continue;
                    v->vc1dsp.vc1_inv_trans_8x8(v->block[v->cur_blk_idx][block_map[i]]);
                    if (v->rangeredfrm)
                        for (j = 0; j < 64; j++)
                            v->block[v->cur_blk_idx][block_map[i]][j] *= 2;
                    block_cbp   |= 0xF << (i << 2);
                    block_intra |= 1 << i;
                } else if (val) {
                    pat = vc1_decode_p_block(v, v->block[v->cur_blk_idx][block_map[i]], i, mquant, ttmb, first_block,
                                             s->dest[dst_idx] + off, (i & 4) ? s->uvlinesize : s->linesize,
                                             CONFIG_GRAY && (i & 4) && (s->avctx->flags & AV_CODEC_FLAG_GRAY), &block_tt);
                    if (pat < 0)
                        return pat;
                    block_cbp |= pat << (i << 2);
                    if (!v->ttmbf && ttmb < 8)
                        ttmb = -1;
                    first_block = 0;
                }
            }
        } else { // skipped
            s->mb_intra = 0;
            for (i = 0; i < 6; i++) {
                v->mb_type[0][s->block_index[i]] = 0;
                s->dc_val[0][s->block_index[i]]  = 0;
            }
            s->current_picture.mb_type[mb_pos]      = MB_TYPE_SKIP;
            s->current_picture.qscale_table[mb_pos] = 0;
            ff_vc1_pred_mv(v, 0, 0, 0, 1, v->range_x, v->range_y, v->mb_type[0], 0, 0);
            ff_vc1_mc_1mv(v, 0);
        }
    } else { // 4MV mode
        if (!skipped /* unskipped MB */) {
            int intra_count = 0, coded_inter = 0;
            int is_intra[6], is_coded[6];
            /* Get CBPCY */
            cbp = get_vlc2(&v->s.gb, v->cbpcy_vlc, VC1_CBPCY_P_VLC_BITS, 2);
            for (i = 0; i < 6; i++) {
                val = ((cbp >> (5 - i)) & 1);
                s->dc_val[0][s->block_index[i]] = 0;
                s->mb_intra                     = 0;
                if (i < 4) {
                    dmv_x = dmv_y = 0;
                    s->mb_intra   = 0;
                    mb_has_coeffs = 0;
                    if (val) {
                        GET_MVDATA(dmv_x, dmv_y);
                    }
                    ff_vc1_pred_mv(v, i, dmv_x, dmv_y, 0, v->range_x, v->range_y, v->mb_type[0], 0, 0);
                    if (!s->mb_intra)
                        ff_vc1_mc_4mv_luma(v, i, 0, 0);
                    intra_count += s->mb_intra;
                    is_intra[i]  = s->mb_intra;
                    is_coded[i]  = mb_has_coeffs;
                }
                if (i & 4) {
                    is_intra[i] = (intra_count >= 3);
                    is_coded[i] = val;
                }
                if (i == 4)
                    ff_vc1_mc_4mv_chroma(v, 0);
                v->mb_type[0][s->block_index[i]] = is_intra[i];
                if (!coded_inter)
                    coded_inter = !is_intra[i] & is_coded[i];
            }
            // if there are no coded blocks then don't do anything more
            dst_idx = 0;
            if (!intra_count && !coded_inter)
                goto end;
            GET_MQUANT();
            s->current_picture.qscale_table[mb_pos] = mquant;
            /* test if block is intra and has pred */
            {
                int intrapred = 0;
                for (i = 0; i < 6; i++)
                    if (is_intra[i]) {
                        if (((!s->first_slice_line || (i == 2 || i == 3)) && v->mb_type[0][s->block_index[i] - s->block_wrap[i]])
                            || ((s->mb_x || (i == 1 || i == 3)) && v->mb_type[0][s->block_index[i] - 1])) {
                            intrapred = 1;
                            break;
                        }
                    }
                if (intrapred)
                    s->ac_pred = get_bits1(gb);
                else
                    s->ac_pred = 0;
            }
            if (!v->ttmbf && coded_inter)
                ttmb = get_vlc2(gb, ff_vc1_ttmb_vlc[v->tt_index], VC1_TTMB_VLC_BITS, 2);
            for (i = 0; i < 6; i++) {
                dst_idx    += i >> 2;
                off         = (i & 4) ? 0 : ((i & 1) * 8 + (i & 2) * 4 * s->linesize);
                s->mb_intra = is_intra[i];
                if (is_intra[i]) {
                    /* check if prediction blocks A and C are available */
                    v->a_avail = v->c_avail = 0;
                    if (i == 2 || i == 3 || !s->first_slice_line)
                        v->a_avail = v->mb_type[0][s->block_index[i] - s->block_wrap[i]];
                    if (i == 1 || i == 3 || s->mb_x)
                        v->c_avail = v->mb_type[0][s->block_index[i] - 1];

                    vc1_decode_intra_block(v, v->block[v->cur_blk_idx][block_map[i]], i, is_coded[i], mquant,
                                           (i & 4) ? v->codingset2 : v->codingset);
                    if (CONFIG_GRAY && (i > 3) && (s->avctx->flags & AV_CODEC_FLAG_GRAY))
                        continue;
                    v->vc1dsp.vc1_inv_trans_8x8(v->block[v->cur_blk_idx][block_map[i]]);
                    if (v->rangeredfrm)
                        for (j = 0; j < 64; j++)
                            v->block[v->cur_blk_idx][block_map[i]][j] *= 2;
                    block_cbp   |= 0xF << (i << 2);
                    block_intra |= 1 << i;
                } else if (is_coded[i]) {
                    pat = vc1_decode_p_block(v, v->block[v->cur_blk_idx][block_map[i]], i, mquant, ttmb,
                                             first_block, s->dest[dst_idx] + off,
                                             (i & 4) ? s->uvlinesize : s->linesize,
                                             CONFIG_GRAY && (i & 4) && (s->avctx->flags & AV_CODEC_FLAG_GRAY),
                                             &block_tt);
                    if (pat < 0)
                        return pat;
                    block_cbp |= pat << (i << 2);
                    if (!v->ttmbf && ttmb < 8)
                        ttmb = -1;
                    first_block = 0;
                }
            }
        } else { // skipped MB
            s->mb_intra                               = 0;
            s->current_picture.qscale_table[mb_pos] = 0;
            for (i = 0; i < 6; i++) {
                v->mb_type[0][s->block_index[i]] = 0;
                s->dc_val[0][s->block_index[i]]  = 0;
            }
            for (i = 0; i < 4; i++) {
                ff_vc1_pred_mv(v, i, 0, 0, 0, v->range_x, v->range_y, v->mb_type[0], 0, 0);
                ff_vc1_mc_4mv_luma(v, i, 0, 0);
            }
            ff_vc1_mc_4mv_chroma(v, 0);
            s->current_picture.qscale_table[mb_pos] = 0;
        }
    }
end:
    if (v->overlap && v->pq >= 9)
        ff_vc1_p_overlap_filter(v);
    vc1_put_blocks_clamped(v, 1);

    v->cbp[s->mb_x]      = block_cbp;
    v->ttblk[s->mb_x]    = block_tt;
    v->is_intra[s->mb_x] = block_intra;

    return 0;
}

/* Decode one macroblock in an interlaced frame p picture */

static int vc1_decode_p_mb_intfr(VC1Context *v)
{
    MpegEncContext *s = &v->s;
    GetBitContext *gb = &s->gb;
    int i;
    int mb_pos = s->mb_x + s->mb_y * s->mb_stride;
    int cbp = 0; /* cbp decoding stuff */
    int mqdiff, mquant; /* MB quantization */
    int ttmb = v->ttfrm; /* MB Transform type */

    int mb_has_coeffs = 1; /* last_flag */
    int dmv_x, dmv_y; /* Differential MV components */
    int val; /* temp value */
    int first_block = 1;
    int dst_idx, off;
    int skipped, fourmv = 0, twomv = 0;
    int block_cbp = 0, pat, block_tt = 0;
    int idx_mbmode = 0, mvbp;
    int fieldtx;

    mquant = v->pq; /* Lossy initialization */

    if (v->skip_is_raw)
        skipped = get_bits1(gb);
    else
        skipped = v->s.mbskip_table[mb_pos];
    if (!skipped) {
        if (v->fourmvswitch)
            idx_mbmode = get_vlc2(gb, v->mbmode_vlc, VC1_INTFR_4MV_MBMODE_VLC_BITS, 2); // try getting this done
        else
            idx_mbmode = get_vlc2(gb, v->mbmode_vlc, VC1_INTFR_NON4MV_MBMODE_VLC_BITS, 2); // in a single line
        switch (ff_vc1_mbmode_intfrp[v->fourmvswitch][idx_mbmode][0]) {
        /* store the motion vector type in a flag (useful later) */
        case MV_PMODE_INTFR_4MV:
            fourmv = 1;
            v->blk_mv_type[s->block_index[0]] = 0;
            v->blk_mv_type[s->block_index[1]] = 0;
            v->blk_mv_type[s->block_index[2]] = 0;
            v->blk_mv_type[s->block_index[3]] = 0;
            break;
        case MV_PMODE_INTFR_4MV_FIELD:
            fourmv = 1;
            v->blk_mv_type[s->block_index[0]] = 1;
            v->blk_mv_type[s->block_index[1]] = 1;
            v->blk_mv_type[s->block_index[2]] = 1;
            v->blk_mv_type[s->block_index[3]] = 1;
            break;
        case MV_PMODE_INTFR_2MV_FIELD:
            twomv = 1;
            v->blk_mv_type[s->block_index[0]] = 1;
            v->blk_mv_type[s->block_index[1]] = 1;
            v->blk_mv_type[s->block_index[2]] = 1;
            v->blk_mv_type[s->block_index[3]] = 1;
            break;
        case MV_PMODE_INTFR_1MV:
            v->blk_mv_type[s->block_index[0]] = 0;
            v->blk_mv_type[s->block_index[1]] = 0;
            v->blk_mv_type[s->block_index[2]] = 0;
            v->blk_mv_type[s->block_index[3]] = 0;
            break;
        }
        if (ff_vc1_mbmode_intfrp[v->fourmvswitch][idx_mbmode][0] == MV_PMODE_INTFR_INTRA) { // intra MB
            for (i = 0; i < 4; i++) {
                s->current_picture.motion_val[1][s->block_index[i]][0] = 0;
                s->current_picture.motion_val[1][s->block_index[i]][1] = 0;
            }
            v->is_intra[s->mb_x] = 0x3f; // Set the bitfield to all 1.
            s->mb_intra          = 1;
            s->current_picture.mb_type[mb_pos] = MB_TYPE_INTRA;
            fieldtx = v->fieldtx_plane[mb_pos] = get_bits1(gb);
            mb_has_coeffs = get_bits1(gb);
            if (mb_has_coeffs)
                cbp = 1 + get_vlc2(&v->s.gb, v->cbpcy_vlc, VC1_CBPCY_P_VLC_BITS, 2);
            v->s.ac_pred = v->acpred_plane[mb_pos] = get_bits1(gb);
            GET_MQUANT();
            s->current_picture.qscale_table[mb_pos] = mquant;
            /* Set DC scale - y and c use the same (not sure if necessary here) */
            s->y_dc_scale = s->y_dc_scale_table[FFABS(mquant)];
            s->c_dc_scale = s->c_dc_scale_table[FFABS(mquant)];
            dst_idx = 0;
            for (i = 0; i < 6; i++) {
                v->a_avail = v->c_avail          = 0;
                v->mb_type[0][s->block_index[i]] = 1;
                s->dc_val[0][s->block_index[i]]  = 0;
                dst_idx += i >> 2;
                val = ((cbp >> (5 - i)) & 1);
                if (i == 2 || i == 3 || !s->first_slice_line)
                    v->a_avail = v->mb_type[0][s->block_index[i] - s->block_wrap[i]];
                if (i == 1 || i == 3 || s->mb_x)
                    v->c_avail = v->mb_type[0][s->block_index[i] - 1];

                vc1_decode_intra_block(v, v->block[v->cur_blk_idx][block_map[i]], i, val, mquant,
                                       (i & 4) ? v->codingset2 : v->codingset);
                if (CONFIG_GRAY && (i > 3) && (s->avctx->flags & AV_CODEC_FLAG_GRAY))
                    continue;
                v->vc1dsp.vc1_inv_trans_8x8(v->block[v->cur_blk_idx][block_map[i]]);
                if (i < 4)
                    off = (fieldtx) ? ((i & 1) * 8) + ((i & 2) >> 1) * s->linesize : (i & 1) * 8 + 4 * (i & 2) * s->linesize;
                else
                    off = 0;
                block_cbp |= 0xf << (i << 2);
            }

        } else { // inter MB
            mb_has_coeffs = ff_vc1_mbmode_intfrp[v->fourmvswitch][idx_mbmode][3];
            if (mb_has_coeffs)
                cbp = 1 + get_vlc2(&v->s.gb, v->cbpcy_vlc, VC1_CBPCY_P_VLC_BITS, 2);
            if (ff_vc1_mbmode_intfrp[v->fourmvswitch][idx_mbmode][0] == MV_PMODE_INTFR_2MV_FIELD) {
                v->twomvbp = get_vlc2(gb, v->twomvbp_vlc, VC1_2MV_BLOCK_PATTERN_VLC_BITS, 1);
            } else {
                if ((ff_vc1_mbmode_intfrp[v->fourmvswitch][idx_mbmode][0] == MV_PMODE_INTFR_4MV)
                    || (ff_vc1_mbmode_intfrp[v->fourmvswitch][idx_mbmode][0] == MV_PMODE_INTFR_4MV_FIELD)) {
                    v->fourmvbp = get_vlc2(gb, v->fourmvbp_vlc, VC1_4MV_BLOCK_PATTERN_VLC_BITS, 1);
                }
            }
            s->mb_intra = v->is_intra[s->mb_x] = 0;
            for (i = 0; i < 6; i++)
                v->mb_type[0][s->block_index[i]] = 0;
            fieldtx = v->fieldtx_plane[mb_pos] = ff_vc1_mbmode_intfrp[v->fourmvswitch][idx_mbmode][1];
            /* for all motion vector read MVDATA and motion compensate each block */
            dst_idx = 0;
            if (fourmv) {
                mvbp = v->fourmvbp;
                for (i = 0; i < 4; i++) {
                    dmv_x = dmv_y = 0;
                    if (mvbp & (8 >> i))
                        get_mvdata_interlaced(v, &dmv_x, &dmv_y, 0);
                    ff_vc1_pred_mv_intfr(v, i, dmv_x, dmv_y, 0, v->range_x, v->range_y, 0);
                    ff_vc1_mc_4mv_luma(v, i, 0, 0);
                }
                ff_vc1_mc_4mv_chroma4(v, 0, 0, 0);
            } else if (twomv) {
                mvbp  = v->twomvbp;
                dmv_x = dmv_y = 0;
                if (mvbp & 2) {
                    get_mvdata_interlaced(v, &dmv_x, &dmv_y, 0);
                }
                ff_vc1_pred_mv_intfr(v, 0, dmv_x, dmv_y, 2, v->range_x, v->range_y, 0);
                ff_vc1_mc_4mv_luma(v, 0, 0, 0);
                ff_vc1_mc_4mv_luma(v, 1, 0, 0);
                dmv_x = dmv_y = 0;
                if (mvbp & 1) {
                    get_mvdata_interlaced(v, &dmv_x, &dmv_y, 0);
                }
                ff_vc1_pred_mv_intfr(v, 2, dmv_x, dmv_y, 2, v->range_x, v->range_y, 0);
                ff_vc1_mc_4mv_luma(v, 2, 0, 0);
                ff_vc1_mc_4mv_luma(v, 3, 0, 0);
                ff_vc1_mc_4mv_chroma4(v, 0, 0, 0);
            } else {
                mvbp = ff_vc1_mbmode_intfrp[v->fourmvswitch][idx_mbmode][2];
                dmv_x = dmv_y = 0;
                if (mvbp) {
                    get_mvdata_interlaced(v, &dmv_x, &dmv_y, 0);
                }
                ff_vc1_pred_mv_intfr(v, 0, dmv_x, dmv_y, 1, v->range_x, v->range_y, 0);
                ff_vc1_mc_1mv(v, 0);
            }
            if (cbp)
                GET_MQUANT();  // p. 227
            s->current_picture.qscale_table[mb_pos] = mquant;
            if (!v->ttmbf && cbp)
                ttmb = get_vlc2(gb, ff_vc1_ttmb_vlc[v->tt_index], VC1_TTMB_VLC_BITS, 2);
            for (i = 0; i < 6; i++) {
                s->dc_val[0][s->block_index[i]] = 0;
                dst_idx += i >> 2;
                val = ((cbp >> (5 - i)) & 1);
                if (!fieldtx)
                    off = (i & 4) ? 0 : ((i & 1) * 8 + (i & 2) * 4 * s->linesize);
                else
                    off = (i & 4) ? 0 : ((i & 1) * 8 + ((i > 1) * s->linesize));
                if (val) {
                    pat = vc1_decode_p_block(v, v->block[v->cur_blk_idx][block_map[i]], i, mquant, ttmb,
                                             first_block, s->dest[dst_idx] + off,
                                             (i & 4) ? s->uvlinesize : (s->linesize << fieldtx),
                                             CONFIG_GRAY && (i & 4) && (s->avctx->flags & AV_CODEC_FLAG_GRAY), &block_tt);
                    if (pat < 0)
                        return pat;
                    block_cbp |= pat << (i << 2);
                    if (!v->ttmbf && ttmb < 8)
                        ttmb = -1;
                    first_block = 0;
                }
            }
        }
    } else { // skipped
        s->mb_intra = v->is_intra[s->mb_x] = 0;
        for (i = 0; i < 6; i++) {
            v->mb_type[0][s->block_index[i]] = 0;
            s->dc_val[0][s->block_index[i]] = 0;
        }
        s->current_picture.mb_type[mb_pos]      = MB_TYPE_SKIP;
        s->current_picture.qscale_table[mb_pos] = 0;
        v->blk_mv_type[s->block_index[0]] = 0;
        v->blk_mv_type[s->block_index[1]] = 0;
        v->blk_mv_type[s->block_index[2]] = 0;
        v->blk_mv_type[s->block_index[3]] = 0;
        ff_vc1_pred_mv_intfr(v, 0, 0, 0, 1, v->range_x, v->range_y, 0);
        ff_vc1_mc_1mv(v, 0);
        v->fieldtx_plane[mb_pos] = 0;
    }
    if (v->overlap && v->pq >= 9)
        ff_vc1_p_overlap_filter(v);
    vc1_put_blocks_clamped(v, 1);

    v->cbp[s->mb_x]      = block_cbp;
    v->ttblk[s->mb_x]    = block_tt;

    return 0;
}

static int vc1_decode_p_mb_intfi(VC1Context *v)
{
    MpegEncContext *s = &v->s;
    GetBitContext *gb = &s->gb;
    int i;
    int mb_pos = s->mb_x + s->mb_y * s->mb_stride;
    int cbp = 0; /* cbp decoding stuff */
    int mqdiff, mquant; /* MB quantization */
    int ttmb = v->ttfrm; /* MB Transform type */

    int mb_has_coeffs = 1; /* last_flag */
    int dmv_x, dmv_y; /* Differential MV components */
    int val; /* temp values */
    int first_block = 1;
    int dst_idx, off;
    int pred_flag = 0;
    int block_cbp = 0, pat, block_tt = 0;
    int idx_mbmode = 0;

    mquant = v->pq; /* Lossy initialization */

    idx_mbmode = get_vlc2(gb, v->mbmode_vlc, VC1_IF_MBMODE_VLC_BITS, 2);
    if (idx_mbmode <= 1) { // intra MB
        v->is_intra[s->mb_x] = 0x3f; // Set the bitfield to all 1.
        s->mb_intra          = 1;
        s->current_picture.motion_val[1][s->block_index[0] + v->blocks_off][0] = 0;
        s->current_picture.motion_val[1][s->block_index[0] + v->blocks_off][1] = 0;
        s->current_picture.mb_type[mb_pos + v->mb_off] = MB_TYPE_INTRA;
        GET_MQUANT();
        s->current_picture.qscale_table[mb_pos] = mquant;
        /* Set DC scale - y and c use the same (not sure if necessary here) */
        s->y_dc_scale = s->y_dc_scale_table[FFABS(mquant)];
        s->c_dc_scale = s->c_dc_scale_table[FFABS(mquant)];
        v->s.ac_pred  = v->acpred_plane[mb_pos] = get_bits1(gb);
        mb_has_coeffs = idx_mbmode & 1;
        if (mb_has_coeffs)
            cbp = 1 + get_vlc2(&v->s.gb, v->cbpcy_vlc, VC1_ICBPCY_VLC_BITS, 2);
        dst_idx = 0;
        for (i = 0; i < 6; i++) {
            v->a_avail = v->c_avail          = 0;
            v->mb_type[0][s->block_index[i]] = 1;
            s->dc_val[0][s->block_index[i]]  = 0;
            dst_idx += i >> 2;
            val = ((cbp >> (5 - i)) & 1);
            if (i == 2 || i == 3 || !s->first_slice_line)
                v->a_avail = v->mb_type[0][s->block_index[i] - s->block_wrap[i]];
            if (i == 1 || i == 3 || s->mb_x)
                v->c_avail = v->mb_type[0][s->block_index[i] - 1];

            vc1_decode_intra_block(v, v->block[v->cur_blk_idx][block_map[i]], i, val, mquant,
                                   (i & 4) ? v->codingset2 : v->codingset);
            if (CONFIG_GRAY && (i > 3) && (s->avctx->flags & AV_CODEC_FLAG_GRAY))
                continue;
            v->vc1dsp.vc1_inv_trans_8x8(v->block[v->cur_blk_idx][block_map[i]]);
            off  = (i & 4) ? 0 : ((i & 1) * 8 + (i & 2) * 4 * s->linesize);
            block_cbp |= 0xf << (i << 2);
        }
    } else {
        s->mb_intra = v->is_intra[s->mb_x] = 0;
        s->current_picture.mb_type[mb_pos + v->mb_off] = MB_TYPE_16x16;
        for (i = 0; i < 6; i++)
            v->mb_type[0][s->block_index[i]] = 0;
        if (idx_mbmode <= 5) { // 1-MV
            dmv_x = dmv_y = pred_flag = 0;
            if (idx_mbmode & 1) {
                get_mvdata_interlaced(v, &dmv_x, &dmv_y, &pred_flag);
            }
            ff_vc1_pred_mv(v, 0, dmv_x, dmv_y, 1, v->range_x, v->range_y, v->mb_type[0], pred_flag, 0);
            ff_vc1_mc_1mv(v, 0);
            mb_has_coeffs = !(idx_mbmode & 2);
        } else { // 4-MV
            v->fourmvbp = get_vlc2(gb, v->fourmvbp_vlc, VC1_4MV_BLOCK_PATTERN_VLC_BITS, 1);
            for (i = 0; i < 4; i++) {
                dmv_x = dmv_y = pred_flag = 0;
                if (v->fourmvbp & (8 >> i))
                    get_mvdata_interlaced(v, &dmv_x, &dmv_y, &pred_flag);
                ff_vc1_pred_mv(v, i, dmv_x, dmv_y, 0, v->range_x, v->range_y, v->mb_type[0], pred_flag, 0);
                ff_vc1_mc_4mv_luma(v, i, 0, 0);
            }
            ff_vc1_mc_4mv_chroma(v, 0);
            mb_has_coeffs = idx_mbmode & 1;
        }
        if (mb_has_coeffs)
            cbp = 1 + get_vlc2(&v->s.gb, v->cbpcy_vlc, VC1_CBPCY_P_VLC_BITS, 2);
        if (cbp) {
            GET_MQUANT();
        }
        s->current_picture.qscale_table[mb_pos] = mquant;
        if (!v->ttmbf && cbp) {
            ttmb = get_vlc2(gb, ff_vc1_ttmb_vlc[v->tt_index], VC1_TTMB_VLC_BITS, 2);
        }
        dst_idx = 0;
        for (i = 0; i < 6; i++) {
            s->dc_val[0][s->block_index[i]] = 0;
            dst_idx += i >> 2;
            val = ((cbp >> (5 - i)) & 1);
            off = (i & 4) ? 0 : (i & 1) * 8 + (i & 2) * 4 * s->linesize;
            if (val) {
                pat = vc1_decode_p_block(v, v->block[v->cur_blk_idx][block_map[i]], i, mquant, ttmb,
                                         first_block, s->dest[dst_idx] + off,
                                         (i & 4) ? s->uvlinesize : s->linesize,
                                         CONFIG_GRAY && (i & 4) && (s->avctx->flags & AV_CODEC_FLAG_GRAY),
                                         &block_tt);
                if (pat < 0)
                    return pat;
                block_cbp |= pat << (i << 2);
                if (!v->ttmbf && ttmb < 8)
                    ttmb = -1;
                first_block = 0;
            }
        }
    }
    if (v->overlap && v->pq >= 9)
        ff_vc1_p_overlap_filter(v);
    vc1_put_blocks_clamped(v, 1);

    v->cbp[s->mb_x]      = block_cbp;
    v->ttblk[s->mb_x]    = block_tt;

    return 0;
}

/** Decode one B-frame MB (in Main profile)
 */
static int vc1_decode_b_mb(VC1Context *v)
{
    MpegEncContext *s = &v->s;
    GetBitContext *gb = &s->gb;
    int i, j;
    int mb_pos = s->mb_x + s->mb_y * s->mb_stride;
    int cbp = 0; /* cbp decoding stuff */
    int mqdiff, mquant; /* MB quantization */
    int ttmb = v->ttfrm; /* MB Transform type */
    int mb_has_coeffs = 0; /* last_flag */
    int index, index1; /* LUT indexes */
    int val, sign; /* temp values */
    int first_block = 1;
    int dst_idx, off;
    int skipped, direct;
    int dmv_x[2], dmv_y[2];
    int bmvtype = BMV_TYPE_BACKWARD;

    mquant      = v->pq; /* lossy initialization */
    s->mb_intra = 0;

    if (v->dmb_is_raw)
        direct = get_bits1(gb);
    else
        direct = v->direct_mb_plane[mb_pos];
    if (v->skip_is_raw)
        skipped = get_bits1(gb);
    else
        skipped = v->s.mbskip_table[mb_pos];

    dmv_x[0] = dmv_x[1] = dmv_y[0] = dmv_y[1] = 0;
    for (i = 0; i < 6; i++) {
        v->mb_type[0][s->block_index[i]] = 0;
        s->dc_val[0][s->block_index[i]]  = 0;
    }
    s->current_picture.qscale_table[mb_pos] = 0;

    if (!direct) {
        if (!skipped) {
            GET_MVDATA(dmv_x[0], dmv_y[0]);
            dmv_x[1] = dmv_x[0];
            dmv_y[1] = dmv_y[0];
        }
        if (skipped || !s->mb_intra) {
            bmvtype = decode012(gb);
            switch (bmvtype) {
            case 0:
                bmvtype = (v->bfraction >= (B_FRACTION_DEN/2)) ? BMV_TYPE_BACKWARD : BMV_TYPE_FORWARD;
                break;
            case 1:
                bmvtype = (v->bfraction >= (B_FRACTION_DEN/2)) ? BMV_TYPE_FORWARD : BMV_TYPE_BACKWARD;
                break;
            case 2:
                bmvtype  = BMV_TYPE_INTERPOLATED;
                dmv_x[0] = dmv_y[0] = 0;
            }
        }
    }
    for (i = 0; i < 6; i++)
        v->mb_type[0][s->block_index[i]] = s->mb_intra;

    if (skipped) {
        if (direct)
            bmvtype = BMV_TYPE_INTERPOLATED;
        ff_vc1_pred_b_mv(v, dmv_x, dmv_y, direct, bmvtype);
        vc1_b_mc(v, dmv_x, dmv_y, direct, bmvtype);
        return 0;
    }
    if (direct) {
        cbp = get_vlc2(&v->s.gb, v->cbpcy_vlc, VC1_CBPCY_P_VLC_BITS, 2);
        GET_MQUANT();
        s->mb_intra = 0;
        s->current_picture.qscale_table[mb_pos] = mquant;
        if (!v->ttmbf)
            ttmb = get_vlc2(gb, ff_vc1_ttmb_vlc[v->tt_index], VC1_TTMB_VLC_BITS, 2);
        dmv_x[0] = dmv_y[0] = dmv_x[1] = dmv_y[1] = 0;
        ff_vc1_pred_b_mv(v, dmv_x, dmv_y, direct, bmvtype);
        vc1_b_mc(v, dmv_x, dmv_y, direct, bmvtype);
    } else {
        if (!mb_has_coeffs && !s->mb_intra) {
            /* no coded blocks - effectively skipped */
            ff_vc1_pred_b_mv(v, dmv_x, dmv_y, direct, bmvtype);
            vc1_b_mc(v, dmv_x, dmv_y, direct, bmvtype);
            return 0;
        }
        if (s->mb_intra && !mb_has_coeffs) {
            GET_MQUANT();
            s->current_picture.qscale_table[mb_pos] = mquant;
            s->ac_pred = get_bits1(gb);
            cbp = 0;
            ff_vc1_pred_b_mv(v, dmv_x, dmv_y, direct, bmvtype);
        } else {
            if (bmvtype == BMV_TYPE_INTERPOLATED) {
                GET_MVDATA(dmv_x[0], dmv_y[0]);
                if (!mb_has_coeffs) {
                    /* interpolated skipped block */
                    ff_vc1_pred_b_mv(v, dmv_x, dmv_y, direct, bmvtype);
                    vc1_b_mc(v, dmv_x, dmv_y, direct, bmvtype);
                    return 0;
                }
            }
            ff_vc1_pred_b_mv(v, dmv_x, dmv_y, direct, bmvtype);
            if (!s->mb_intra) {
                vc1_b_mc(v, dmv_x, dmv_y, direct, bmvtype);
            }
            if (s->mb_intra)
                s->ac_pred = get_bits1(gb);
            cbp = get_vlc2(&v->s.gb, v->cbpcy_vlc, VC1_CBPCY_P_VLC_BITS, 2);
            GET_MQUANT();
            s->current_picture.qscale_table[mb_pos] = mquant;
            if (!v->ttmbf && !s->mb_intra && mb_has_coeffs)
                ttmb = get_vlc2(gb, ff_vc1_ttmb_vlc[v->tt_index], VC1_TTMB_VLC_BITS, 2);
        }
    }
    dst_idx = 0;
    for (i = 0; i < 6; i++) {
        s->dc_val[0][s->block_index[i]] = 0;
        dst_idx += i >> 2;
        val = ((cbp >> (5 - i)) & 1);
        off = (i & 4) ? 0 : ((i & 1) * 8 + (i & 2) * 4 * s->linesize);
        v->mb_type[0][s->block_index[i]] = s->mb_intra;
        if (s->mb_intra) {
            /* check if prediction blocks A and C are available */
            v->a_avail = v->c_avail = 0;
            if (i == 2 || i == 3 || !s->first_slice_line)
                v->a_avail = v->mb_type[0][s->block_index[i] - s->block_wrap[i]];
            if (i == 1 || i == 3 || s->mb_x)
                v->c_avail = v->mb_type[0][s->block_index[i] - 1];

            vc1_decode_intra_block(v, s->block[i], i, val, mquant,
                                   (i & 4) ? v->codingset2 : v->codingset);
            if (CONFIG_GRAY && (i > 3) && (s->avctx->flags & AV_CODEC_FLAG_GRAY))
                continue;
            v->vc1dsp.vc1_inv_trans_8x8(s->block[i]);
            if (v->rangeredfrm)
                for (j = 0; j < 64; j++)
                    s->block[i][j] *= 2;
            s->idsp.put_signed_pixels_clamped(s->block[i],
                                              s->dest[dst_idx] + off,
                                              i & 4 ? s->uvlinesize
                                                    : s->linesize);
        } else if (val) {
            int pat = vc1_decode_p_block(v, s->block[i], i, mquant, ttmb,
                                         first_block, s->dest[dst_idx] + off,
                                         (i & 4) ? s->uvlinesize : s->linesize,
                                         CONFIG_GRAY && (i & 4) && (s->avctx->flags & AV_CODEC_FLAG_GRAY), NULL);
            if (pat < 0)
                return pat;
            if (!v->ttmbf && ttmb < 8)
                ttmb = -1;
            first_block = 0;
        }
    }
    return 0;
}

/** Decode one B-frame MB (in interlaced field B picture)
 */
static int vc1_decode_b_mb_intfi(VC1Context *v)
{
    MpegEncContext *s = &v->s;
    GetBitContext *gb = &s->gb;
    int i, j;
    int mb_pos = s->mb_x + s->mb_y * s->mb_stride;
    int cbp = 0; /* cbp decoding stuff */
    int mqdiff, mquant; /* MB quantization */
    int ttmb = v->ttfrm; /* MB Transform type */
    int mb_has_coeffs = 0; /* last_flag */
    int val; /* temp value */
    int first_block = 1;
    int dst_idx, off;
    int fwd;
    int dmv_x[2], dmv_y[2], pred_flag[2];
    int bmvtype = BMV_TYPE_BACKWARD;
    int block_cbp = 0, pat, block_tt = 0;
    int idx_mbmode;

    mquant      = v->pq; /* Lossy initialization */
    s->mb_intra = 0;

    idx_mbmode = get_vlc2(gb, v->mbmode_vlc, VC1_IF_MBMODE_VLC_BITS, 2);
    if (idx_mbmode <= 1) { // intra MB
        v->is_intra[s->mb_x] = 0x3f; // Set the bitfield to all 1.
        s->mb_intra          = 1;
        s->current_picture.motion_val[1][s->block_index[0]][0] = 0;
        s->current_picture.motion_val[1][s->block_index[0]][1] = 0;
        s->current_picture.mb_type[mb_pos + v->mb_off]         = MB_TYPE_INTRA;
        GET_MQUANT();
        s->current_picture.qscale_table[mb_pos] = mquant;
        /* Set DC scale - y and c use the same (not sure if necessary here) */
        s->y_dc_scale = s->y_dc_scale_table[FFABS(mquant)];
        s->c_dc_scale = s->c_dc_scale_table[FFABS(mquant)];
        v->s.ac_pred  = v->acpred_plane[mb_pos] = get_bits1(gb);
        mb_has_coeffs = idx_mbmode & 1;
        if (mb_has_coeffs)
            cbp = 1 + get_vlc2(&v->s.gb, v->cbpcy_vlc, VC1_ICBPCY_VLC_BITS, 2);
        dst_idx = 0;
        for (i = 0; i < 6; i++) {
            v->a_avail = v->c_avail          = 0;
            v->mb_type[0][s->block_index[i]] = 1;
            s->dc_val[0][s->block_index[i]]  = 0;
            dst_idx += i >> 2;
            val = ((cbp >> (5 - i)) & 1);
            if (i == 2 || i == 3 || !s->first_slice_line)
                v->a_avail = v->mb_type[0][s->block_index[i] - s->block_wrap[i]];
            if (i == 1 || i == 3 || s->mb_x)
                v->c_avail = v->mb_type[0][s->block_index[i] - 1];

            vc1_decode_intra_block(v, s->block[i], i, val, mquant,
                                   (i & 4) ? v->codingset2 : v->codingset);
            if (CONFIG_GRAY && (i > 3) && (s->avctx->flags & AV_CODEC_FLAG_GRAY))
                continue;
            v->vc1dsp.vc1_inv_trans_8x8(s->block[i]);
            if (v->rangeredfrm)
                for (j = 0; j < 64; j++)
                    s->block[i][j] <<= 1;
            off  = (i & 4) ? 0 : ((i & 1) * 8 + (i & 2) * 4 * s->linesize);
            s->idsp.put_signed_pixels_clamped(s->block[i],
                                              s->dest[dst_idx] + off,
                                              (i & 4) ? s->uvlinesize
                                                      : s->linesize);
        }
    } else {
        s->mb_intra = v->is_intra[s->mb_x] = 0;
        s->current_picture.mb_type[mb_pos + v->mb_off] = MB_TYPE_16x16;
        for (i = 0; i < 6; i++)
            v->mb_type[0][s->block_index[i]] = 0;
        if (v->fmb_is_raw)
            fwd = v->forward_mb_plane[mb_pos] = get_bits1(gb);
        else
            fwd = v->forward_mb_plane[mb_pos];
        if (idx_mbmode <= 5) { // 1-MV
            int interpmvp = 0;
            dmv_x[0]     = dmv_x[1] = dmv_y[0] = dmv_y[1] = 0;
            pred_flag[0] = pred_flag[1] = 0;
            if (fwd)
                bmvtype = BMV_TYPE_FORWARD;
            else {
                bmvtype = decode012(gb);
                switch (bmvtype) {
                case 0:
                    bmvtype = BMV_TYPE_BACKWARD;
                    break;
                case 1:
                    bmvtype = BMV_TYPE_DIRECT;
                    break;
                case 2:
                    bmvtype   = BMV_TYPE_INTERPOLATED;
                    interpmvp = get_bits1(gb);
                }
            }
            v->bmvtype = bmvtype;
            if (bmvtype != BMV_TYPE_DIRECT && idx_mbmode & 1) {
                get_mvdata_interlaced(v, &dmv_x[bmvtype == BMV_TYPE_BACKWARD], &dmv_y[bmvtype == BMV_TYPE_BACKWARD], &pred_flag[bmvtype == BMV_TYPE_BACKWARD]);
            }
            if (interpmvp) {
                get_mvdata_interlaced(v, &dmv_x[1], &dmv_y[1], &pred_flag[1]);
            }
            if (bmvtype == BMV_TYPE_DIRECT) {
                dmv_x[0] = dmv_y[0] = pred_flag[0] = 0;
                dmv_x[1] = dmv_y[1] = pred_flag[0] = 0;
                if (!s->next_picture_ptr->field_picture) {
                    av_log(s->avctx, AV_LOG_ERROR, "Mixed field/frame direct mode not supported\n");
                    return AVERROR_INVALIDDATA;
                }
            }
            ff_vc1_pred_b_mv_intfi(v, 0, dmv_x, dmv_y, 1, pred_flag);
            vc1_b_mc(v, dmv_x, dmv_y, (bmvtype == BMV_TYPE_DIRECT), bmvtype);
            mb_has_coeffs = !(idx_mbmode & 2);
        } else { // 4-MV
            if (fwd)
                bmvtype = BMV_TYPE_FORWARD;
            v->bmvtype  = bmvtype;
            v->fourmvbp = get_vlc2(gb, v->fourmvbp_vlc, VC1_4MV_BLOCK_PATTERN_VLC_BITS, 1);
            for (i = 0; i < 4; i++) {
                dmv_x[0] = dmv_y[0] = pred_flag[0] = 0;
                dmv_x[1] = dmv_y[1] = pred_flag[1] = 0;
                if (v->fourmvbp & (8 >> i)) {
                    get_mvdata_interlaced(v, &dmv_x[bmvtype == BMV_TYPE_BACKWARD],
                                             &dmv_y[bmvtype == BMV_TYPE_BACKWARD],
                                         &pred_flag[bmvtype == BMV_TYPE_BACKWARD]);
                }
                ff_vc1_pred_b_mv_intfi(v, i, dmv_x, dmv_y, 0, pred_flag);
                ff_vc1_mc_4mv_luma(v, i, bmvtype == BMV_TYPE_BACKWARD, 0);
            }
            ff_vc1_mc_4mv_chroma(v, bmvtype == BMV_TYPE_BACKWARD);
            mb_has_coeffs = idx_mbmode & 1;
        }
        if (mb_has_coeffs)
            cbp = 1 + get_vlc2(&v->s.gb, v->cbpcy_vlc, VC1_CBPCY_P_VLC_BITS, 2);
        if (cbp) {
            GET_MQUANT();
        }
        s->current_picture.qscale_table[mb_pos] = mquant;
        if (!v->ttmbf && cbp) {
            ttmb = get_vlc2(gb, ff_vc1_ttmb_vlc[v->tt_index], VC1_TTMB_VLC_BITS, 2);
        }
        dst_idx = 0;
        for (i = 0; i < 6; i++) {
            s->dc_val[0][s->block_index[i]] = 0;
            dst_idx += i >> 2;
            val = ((cbp >> (5 - i)) & 1);
            off = (i & 4) ? 0 : (i & 1) * 8 + (i & 2) * 4 * s->linesize;
            if (val) {
                pat = vc1_decode_p_block(v, s->block[i], i, mquant, ttmb,
                                         first_block, s->dest[dst_idx] + off,
                                         (i & 4) ? s->uvlinesize : s->linesize,
                                         CONFIG_GRAY && (i & 4) && (s->avctx->flags & AV_CODEC_FLAG_GRAY), &block_tt);
                if (pat < 0)
                    return pat;
                block_cbp |= pat << (i << 2);
                if (!v->ttmbf && ttmb < 8)
                    ttmb = -1;
                first_block = 0;
            }
        }
    }
    v->cbp[s->mb_x]      = block_cbp;
    v->ttblk[s->mb_x]    = block_tt;

    return 0;
}

/** Decode one B-frame MB (in interlaced frame B picture)
 */
static int vc1_decode_b_mb_intfr(VC1Context *v)
{
    MpegEncContext *s = &v->s;
    GetBitContext *gb = &s->gb;
    int i, j;
    int mb_pos = s->mb_x + s->mb_y * s->mb_stride;
    int cbp = 0; /* cbp decoding stuff */
    int mqdiff, mquant; /* MB quantization */
    int ttmb = v->ttfrm; /* MB Transform type */
    int mvsw = 0; /* motion vector switch */
    int mb_has_coeffs = 1; /* last_flag */
    int dmv_x, dmv_y; /* Differential MV components */
    int val; /* temp value */
    int first_block = 1;
    int dst_idx, off;
    int skipped, direct, twomv = 0;
    int block_cbp = 0, pat, block_tt = 0;
    int idx_mbmode = 0, mvbp;
    int stride_y, fieldtx;
    int bmvtype = BMV_TYPE_BACKWARD;
    int dir, dir2;

    mquant = v->pq; /* Lossy initialization */
    s->mb_intra = 0;
    if (v->skip_is_raw)
        skipped = get_bits1(gb);
    else
        skipped = v->s.mbskip_table[mb_pos];

    if (!skipped) {
        idx_mbmode = get_vlc2(gb, v->mbmode_vlc, VC1_INTFR_NON4MV_MBMODE_VLC_BITS, 2);
        if (ff_vc1_mbmode_intfrp[0][idx_mbmode][0] == MV_PMODE_INTFR_2MV_FIELD) {
            twomv = 1;
            v->blk_mv_type[s->block_index[0]] = 1;
            v->blk_mv_type[s->block_index[1]] = 1;
            v->blk_mv_type[s->block_index[2]] = 1;
            v->blk_mv_type[s->block_index[3]] = 1;
        } else {
            v->blk_mv_type[s->block_index[0]] = 0;
            v->blk_mv_type[s->block_index[1]] = 0;
            v->blk_mv_type[s->block_index[2]] = 0;
            v->blk_mv_type[s->block_index[3]] = 0;
        }
    }

    if (ff_vc1_mbmode_intfrp[0][idx_mbmode][0] == MV_PMODE_INTFR_INTRA) { // intra MB
        for (i = 0; i < 4; i++) {
            s->mv[0][i][0] = s->current_picture.motion_val[0][s->block_index[i]][0] = 0;
            s->mv[0][i][1] = s->current_picture.motion_val[0][s->block_index[i]][1] = 0;
            s->mv[1][i][0] = s->current_picture.motion_val[1][s->block_index[i]][0] = 0;
            s->mv[1][i][1] = s->current_picture.motion_val[1][s->block_index[i]][1] = 0;
        }
        v->is_intra[s->mb_x] = 0x3f; // Set the bitfield to all 1.
        s->mb_intra          = 1;
        s->current_picture.mb_type[mb_pos] = MB_TYPE_INTRA;
        fieldtx = v->fieldtx_plane[mb_pos] = get_bits1(gb);
        mb_has_coeffs = get_bits1(gb);
        if (mb_has_coeffs)
            cbp = 1 + get_vlc2(&v->s.gb, v->cbpcy_vlc, VC1_CBPCY_P_VLC_BITS, 2);
        v->s.ac_pred = v->acpred_plane[mb_pos] = get_bits1(gb);
        GET_MQUANT();
        s->current_picture.qscale_table[mb_pos] = mquant;
        /* Set DC scale - y and c use the same (not sure if necessary here) */
        s->y_dc_scale = s->y_dc_scale_table[FFABS(mquant)];
        s->c_dc_scale = s->c_dc_scale_table[FFABS(mquant)];
        dst_idx = 0;
        for (i = 0; i < 6; i++) {
            v->a_avail = v->c_avail          = 0;
            v->mb_type[0][s->block_index[i]] = 1;
            s->dc_val[0][s->block_index[i]]  = 0;
            dst_idx += i >> 2;
            val = ((cbp >> (5 - i)) & 1);
            if (i == 2 || i == 3 || !s->first_slice_line)
                v->a_avail = v->mb_type[0][s->block_index[i] - s->block_wrap[i]];
            if (i == 1 || i == 3 || s->mb_x)
                v->c_avail = v->mb_type[0][s->block_index[i] - 1];

            vc1_decode_intra_block(v, s->block[i], i, val, mquant,
                                   (i & 4) ? v->codingset2 : v->codingset);
            if (CONFIG_GRAY && i > 3 && (s->avctx->flags & AV_CODEC_FLAG_GRAY))
                continue;
            v->vc1dsp.vc1_inv_trans_8x8(s->block[i]);
            if (i < 4) {
                stride_y = s->linesize << fieldtx;
                off = (fieldtx) ? ((i & 1) * 8) + ((i & 2) >> 1) * s->linesize : (i & 1) * 8 + 4 * (i & 2) * s->linesize;
            } else {
                stride_y = s->uvlinesize;
                off = 0;
            }
            s->idsp.put_signed_pixels_clamped(s->block[i],
                                              s->dest[dst_idx] + off,
                                              stride_y);
        }
    } else {
        s->mb_intra = v->is_intra[s->mb_x] = 0;

        if (v->dmb_is_raw)
            direct = get_bits1(gb);
        else
            direct = v->direct_mb_plane[mb_pos];

        if (direct) {
            if (s->next_picture_ptr->field_picture)
                av_log(s->avctx, AV_LOG_WARNING, "Mixed frame/field direct mode not supported\n");
            s->mv[0][0][0] = s->current_picture.motion_val[0][s->block_index[0]][0] = scale_mv(s->next_picture.motion_val[1][s->block_index[0]][0], v->bfraction, 0, s->quarter_sample);
            s->mv[0][0][1] = s->current_picture.motion_val[0][s->block_index[0]][1] = scale_mv(s->next_picture.motion_val[1][s->block_index[0]][1], v->bfraction, 0, s->quarter_sample);
            s->mv[1][0][0] = s->current_picture.motion_val[1][s->block_index[0]][0] = scale_mv(s->next_picture.motion_val[1][s->block_index[0]][0], v->bfraction, 1, s->quarter_sample);
            s->mv[1][0][1] = s->current_picture.motion_val[1][s->block_index[0]][1] = scale_mv(s->next_picture.motion_val[1][s->block_index[0]][1], v->bfraction, 1, s->quarter_sample);

            if (twomv) {
                s->mv[0][2][0] = s->current_picture.motion_val[0][s->block_index[2]][0] = scale_mv(s->next_picture.motion_val[1][s->block_index[2]][0], v->bfraction, 0, s->quarter_sample);
                s->mv[0][2][1] = s->current_picture.motion_val[0][s->block_index[2]][1] = scale_mv(s->next_picture.motion_val[1][s->block_index[2]][1], v->bfraction, 0, s->quarter_sample);
                s->mv[1][2][0] = s->current_picture.motion_val[1][s->block_index[2]][0] = scale_mv(s->next_picture.motion_val[1][s->block_index[2]][0], v->bfraction, 1, s->quarter_sample);
                s->mv[1][2][1] = s->current_picture.motion_val[1][s->block_index[2]][1] = scale_mv(s->next_picture.motion_val[1][s->block_index[2]][1], v->bfraction, 1, s->quarter_sample);

                for (i = 1; i < 4; i += 2) {
                    s->mv[0][i][0] = s->current_picture.motion_val[0][s->block_index[i]][0] = s->mv[0][i-1][0];
                    s->mv[0][i][1] = s->current_picture.motion_val[0][s->block_index[i]][1] = s->mv[0][i-1][1];
                    s->mv[1][i][0] = s->current_picture.motion_val[1][s->block_index[i]][0] = s->mv[1][i-1][0];
                    s->mv[1][i][1] = s->current_picture.motion_val[1][s->block_index[i]][1] = s->mv[1][i-1][1];
                }
            } else {
                for (i = 1; i < 4; i++) {
                    s->mv[0][i][0] = s->current_picture.motion_val[0][s->block_index[i]][0] = s->mv[0][0][0];
                    s->mv[0][i][1] = s->current_picture.motion_val[0][s->block_index[i]][1] = s->mv[0][0][1];
                    s->mv[1][i][0] = s->current_picture.motion_val[1][s->block_index[i]][0] = s->mv[1][0][0];
                    s->mv[1][i][1] = s->current_picture.motion_val[1][s->block_index[i]][1] = s->mv[1][0][1];
                }
            }
        }

        if (!direct) {
            if (skipped || !s->mb_intra) {
                bmvtype = decode012(gb);
                switch (bmvtype) {
                case 0:
                    bmvtype = (v->bfraction >= (B_FRACTION_DEN/2)) ? BMV_TYPE_BACKWARD : BMV_TYPE_FORWARD;
                    break;
                case 1:
                    bmvtype = (v->bfraction >= (B_FRACTION_DEN/2)) ? BMV_TYPE_FORWARD : BMV_TYPE_BACKWARD;
                    break;
                case 2:
                    bmvtype  = BMV_TYPE_INTERPOLATED;
                }
            }

            if (twomv && bmvtype != BMV_TYPE_INTERPOLATED)
                mvsw = get_bits1(gb);
        }

        if (!skipped) { // inter MB
            mb_has_coeffs = ff_vc1_mbmode_intfrp[0][idx_mbmode][3];
            if (mb_has_coeffs)
                cbp = 1 + get_vlc2(&v->s.gb, v->cbpcy_vlc, VC1_CBPCY_P_VLC_BITS, 2);
            if (!direct) {
                if (bmvtype == BMV_TYPE_INTERPOLATED && twomv) {
                    v->fourmvbp = get_vlc2(gb, v->fourmvbp_vlc, VC1_4MV_BLOCK_PATTERN_VLC_BITS, 1);
                } else if (bmvtype == BMV_TYPE_INTERPOLATED || twomv) {
                    v->twomvbp = get_vlc2(gb, v->twomvbp_vlc, VC1_2MV_BLOCK_PATTERN_VLC_BITS, 1);
                }
            }

            for (i = 0; i < 6; i++)
                v->mb_type[0][s->block_index[i]] = 0;
            fieldtx = v->fieldtx_plane[mb_pos] = ff_vc1_mbmode_intfrp[0][idx_mbmode][1];
            /* for all motion vector read MVDATA and motion compensate each block */
            dst_idx = 0;
            if (direct) {
                if (twomv) {
                    for (i = 0; i < 4; i++) {
                        ff_vc1_mc_4mv_luma(v, i, 0, 0);
                        ff_vc1_mc_4mv_luma(v, i, 1, 1);
                    }
                    ff_vc1_mc_4mv_chroma4(v, 0, 0, 0);
                    ff_vc1_mc_4mv_chroma4(v, 1, 1, 1);
                } else {
                    ff_vc1_mc_1mv(v, 0);
                    ff_vc1_interp_mc(v);
                }
            } else if (twomv && bmvtype == BMV_TYPE_INTERPOLATED) {
                mvbp = v->fourmvbp;
                for (i = 0; i < 4; i++) {
                    dir = i==1 || i==3;
                    dmv_x = dmv_y = 0;
                    val = ((mvbp >> (3 - i)) & 1);
                    if (val)
                        get_mvdata_interlaced(v, &dmv_x, &dmv_y, 0);
                    j = i > 1 ? 2 : 0;
                    ff_vc1_pred_mv_intfr(v, j, dmv_x, dmv_y, 2, v->range_x, v->range_y, dir);
                    ff_vc1_mc_4mv_luma(v, j, dir, dir);
                    ff_vc1_mc_4mv_luma(v, j+1, dir, dir);
                }

                ff_vc1_mc_4mv_chroma4(v, 0, 0, 0);
                ff_vc1_mc_4mv_chroma4(v, 1, 1, 1);
            } else if (bmvtype == BMV_TYPE_INTERPOLATED) {
                mvbp = v->twomvbp;
                dmv_x = dmv_y = 0;
                if (mvbp & 2)
                    get_mvdata_interlaced(v, &dmv_x, &dmv_y, 0);

                ff_vc1_pred_mv_intfr(v, 0, dmv_x, dmv_y, 1, v->range_x, v->range_y, 0);
                ff_vc1_mc_1mv(v, 0);

                dmv_x = dmv_y = 0;
                if (mvbp & 1)
                    get_mvdata_interlaced(v, &dmv_x, &dmv_y, 0);

                ff_vc1_pred_mv_intfr(v, 0, dmv_x, dmv_y, 1, v->range_x, v->range_y, 1);
                ff_vc1_interp_mc(v);
            } else if (twomv) {
                dir = bmvtype == BMV_TYPE_BACKWARD;
                dir2 = dir;
                if (mvsw)
                    dir2 = !dir;
                mvbp = v->twomvbp;
                dmv_x = dmv_y = 0;
                if (mvbp & 2)
                    get_mvdata_interlaced(v, &dmv_x, &dmv_y, 0);
                ff_vc1_pred_mv_intfr(v, 0, dmv_x, dmv_y, 2, v->range_x, v->range_y, dir);

                dmv_x = dmv_y = 0;
                if (mvbp & 1)
                    get_mvdata_interlaced(v, &dmv_x, &dmv_y, 0);
                ff_vc1_pred_mv_intfr(v, 2, dmv_x, dmv_y, 2, v->range_x, v->range_y, dir2);

                if (mvsw) {
                    for (i = 0; i < 2; i++) {
                        s->mv[dir][i+2][0] = s->mv[dir][i][0] = s->current_picture.motion_val[dir][s->block_index[i+2]][0] = s->current_picture.motion_val[dir][s->block_index[i]][0];
                        s->mv[dir][i+2][1] = s->mv[dir][i][1] = s->current_picture.motion_val[dir][s->block_index[i+2]][1] = s->current_picture.motion_val[dir][s->block_index[i]][1];
                        s->mv[dir2][i+2][0] = s->mv[dir2][i][0] = s->current_picture.motion_val[dir2][s->block_index[i]][0] = s->current_picture.motion_val[dir2][s->block_index[i+2]][0];
                        s->mv[dir2][i+2][1] = s->mv[dir2][i][1] = s->current_picture.motion_val[dir2][s->block_index[i]][1] = s->current_picture.motion_val[dir2][s->block_index[i+2]][1];
                    }
                } else {
                    ff_vc1_pred_mv_intfr(v, 0, 0, 0, 2, v->range_x, v->range_y, !dir);
                    ff_vc1_pred_mv_intfr(v, 2, 0, 0, 2, v->range_x, v->range_y, !dir);
                }

                ff_vc1_mc_4mv_luma(v, 0, dir, 0);
                ff_vc1_mc_4mv_luma(v, 1, dir, 0);
                ff_vc1_mc_4mv_luma(v, 2, dir2, 0);
                ff_vc1_mc_4mv_luma(v, 3, dir2, 0);
                ff_vc1_mc_4mv_chroma4(v, dir, dir2, 0);
            } else {
                dir = bmvtype == BMV_TYPE_BACKWARD;

                mvbp = ff_vc1_mbmode_intfrp[0][idx_mbmode][2];
                dmv_x = dmv_y = 0;
                if (mvbp)
                    get_mvdata_interlaced(v, &dmv_x, &dmv_y, 0);

                ff_vc1_pred_mv_intfr(v, 0, dmv_x, dmv_y, 1, v->range_x, v->range_y, dir);
                v->blk_mv_type[s->block_index[0]] = 1;
                v->blk_mv_type[s->block_index[1]] = 1;
                v->blk_mv_type[s->block_index[2]] = 1;
                v->blk_mv_type[s->block_index[3]] = 1;
                ff_vc1_pred_mv_intfr(v, 0, 0, 0, 2, v->range_x, v->range_y, !dir);
                for (i = 0; i < 2; i++) {
                    s->mv[!dir][i+2][0] = s->mv[!dir][i][0] = s->current_picture.motion_val[!dir][s->block_index[i+2]][0] = s->current_picture.motion_val[!dir][s->block_index[i]][0];
                    s->mv[!dir][i+2][1] = s->mv[!dir][i][1] = s->current_picture.motion_val[!dir][s->block_index[i+2]][1] = s->current_picture.motion_val[!dir][s->block_index[i]][1];
                }
                ff_vc1_mc_1mv(v, dir);
            }

            if (cbp)
                GET_MQUANT();  // p. 227
            s->current_picture.qscale_table[mb_pos] = mquant;
            if (!v->ttmbf && cbp)
                ttmb = get_vlc2(gb, ff_vc1_ttmb_vlc[v->tt_index], VC1_TTMB_VLC_BITS, 2);
            for (i = 0; i < 6; i++) {
                s->dc_val[0][s->block_index[i]] = 0;
                dst_idx += i >> 2;
                val = ((cbp >> (5 - i)) & 1);
                if (!fieldtx)
                    off = (i & 4) ? 0 : ((i & 1) * 8 + (i & 2) * 4 * s->linesize);
                else
                    off = (i & 4) ? 0 : ((i & 1) * 8 + ((i > 1) * s->linesize));
                if (val) {
                    pat = vc1_decode_p_block(v, s->block[i], i, mquant, ttmb,
                                             first_block, s->dest[dst_idx] + off,
                                             (i & 4) ? s->uvlinesize : (s->linesize << fieldtx),
                                             CONFIG_GRAY && (i & 4) && (s->avctx->flags & AV_CODEC_FLAG_GRAY), &block_tt);
                    if (pat < 0)
                        return pat;
                    block_cbp |= pat << (i << 2);
                    if (!v->ttmbf && ttmb < 8)
                        ttmb = -1;
                    first_block = 0;
                }
            }

        } else { // skipped
            dir = 0;
            for (i = 0; i < 6; i++) {
                v->mb_type[0][s->block_index[i]] = 0;
                s->dc_val[0][s->block_index[i]] = 0;
            }
            s->current_picture.mb_type[mb_pos]      = MB_TYPE_SKIP;
            s->current_picture.qscale_table[mb_pos] = 0;
            v->blk_mv_type[s->block_index[0]] = 0;
            v->blk_mv_type[s->block_index[1]] = 0;
            v->blk_mv_type[s->block_index[2]] = 0;
            v->blk_mv_type[s->block_index[3]] = 0;

            if (!direct) {
                if (bmvtype == BMV_TYPE_INTERPOLATED) {
                    ff_vc1_pred_mv_intfr(v, 0, 0, 0, 1, v->range_x, v->range_y, 0);
                    ff_vc1_pred_mv_intfr(v, 0, 0, 0, 1, v->range_x, v->range_y, 1);
                } else {
                    dir = bmvtype == BMV_TYPE_BACKWARD;
                    ff_vc1_pred_mv_intfr(v, 0, 0, 0, 1, v->range_x, v->range_y, dir);
                    if (mvsw) {
                        int dir2 = dir;
                        if (mvsw)
                            dir2 = !dir;
                        for (i = 0; i < 2; i++) {
                            s->mv[dir][i+2][0] = s->mv[dir][i][0] = s->current_picture.motion_val[dir][s->block_index[i+2]][0] = s->current_picture.motion_val[dir][s->block_index[i]][0];
                            s->mv[dir][i+2][1] = s->mv[dir][i][1] = s->current_picture.motion_val[dir][s->block_index[i+2]][1] = s->current_picture.motion_val[dir][s->block_index[i]][1];
                            s->mv[dir2][i+2][0] = s->mv[dir2][i][0] = s->current_picture.motion_val[dir2][s->block_index[i]][0] = s->current_picture.motion_val[dir2][s->block_index[i+2]][0];
                            s->mv[dir2][i+2][1] = s->mv[dir2][i][1] = s->current_picture.motion_val[dir2][s->block_index[i]][1] = s->current_picture.motion_val[dir2][s->block_index[i+2]][1];
                        }
                    } else {
                        v->blk_mv_type[s->block_index[0]] = 1;
                        v->blk_mv_type[s->block_index[1]] = 1;
                        v->blk_mv_type[s->block_index[2]] = 1;
                        v->blk_mv_type[s->block_index[3]] = 1;
                        ff_vc1_pred_mv_intfr(v, 0, 0, 0, 2, v->range_x, v->range_y, !dir);
                        for (i = 0; i < 2; i++) {
                            s->mv[!dir][i+2][0] = s->mv[!dir][i][0] = s->current_picture.motion_val[!dir][s->block_index[i+2]][0] = s->current_picture.motion_val[!dir][s->block_index[i]][0];
                            s->mv[!dir][i+2][1] = s->mv[!dir][i][1] = s->current_picture.motion_val[!dir][s->block_index[i+2]][1] = s->current_picture.motion_val[!dir][s->block_index[i]][1];
                        }
                    }
                }
            }

            ff_vc1_mc_1mv(v, dir);
            if (direct || bmvtype == BMV_TYPE_INTERPOLATED) {
                ff_vc1_interp_mc(v);
            }
            v->fieldtx_plane[mb_pos] = 0;
        }
    }
    v->cbp[s->mb_x]      = block_cbp;
    v->ttblk[s->mb_x]    = block_tt;

    return 0;
}

/** Decode blocks of I-frame
 */
static void vc1_decode_i_blocks(VC1Context *v)
{
    int k, j;
    MpegEncContext *s = &v->s;
    int cbp, val;
    uint8_t *coded_val;
    int mb_pos;

    /* select coding mode used for VLC tables selection */
    switch (v->y_ac_table_index) {
    case 0:
        v->codingset = (v->pqindex <= 8) ? CS_HIGH_RATE_INTRA : CS_LOW_MOT_INTRA;
        break;
    case 1:
        v->codingset = CS_HIGH_MOT_INTRA;
        break;
    case 2:
        v->codingset = CS_MID_RATE_INTRA;
        break;
    }

    switch (v->c_ac_table_index) {
    case 0:
        v->codingset2 = (v->pqindex <= 8) ? CS_HIGH_RATE_INTER : CS_LOW_MOT_INTER;
        break;
    case 1:
        v->codingset2 = CS_HIGH_MOT_INTER;
        break;
    case 2:
        v->codingset2 = CS_MID_RATE_INTER;
        break;
    }

    /* Set DC scale - y and c use the same */
    s->y_dc_scale = s->y_dc_scale_table[v->pq];
    s->c_dc_scale = s->c_dc_scale_table[v->pq];

    //do frame decode
    s->mb_x = s->mb_y = 0;
    s->mb_intra         = 1;
    s->first_slice_line = 1;
    for (s->mb_y = s->start_mb_y; s->mb_y < s->end_mb_y; s->mb_y++) {
        s->mb_x = 0;
        init_block_index(v);
        for (; s->mb_x < v->end_mb_x; s->mb_x++) {
            update_block_index(s);
            s->bdsp.clear_blocks(v->block[v->cur_blk_idx][0]);
            mb_pos = s->mb_x + s->mb_y * s->mb_width;
            s->current_picture.mb_type[mb_pos]                     = MB_TYPE_INTRA;
            s->current_picture.qscale_table[mb_pos]                = v->pq;
            for (int i = 0; i < 4; i++) {
                s->current_picture.motion_val[1][s->block_index[i]][0] = 0;
                s->current_picture.motion_val[1][s->block_index[i]][1] = 0;
            }

            // do actual MB decoding and displaying
            cbp = get_vlc2(&v->s.gb, ff_msmp4_mb_i_vlc,
                           MSMP4_MB_INTRA_VLC_BITS, 2);
            v->s.ac_pred = get_bits1(&v->s.gb);

            for (k = 0; k < 6; k++) {
                v->mb_type[0][s->block_index[k]] = 1;

                val = ((cbp >> (5 - k)) & 1);

                if (k < 4) {
                    int pred   = vc1_coded_block_pred(&v->s, k, &coded_val);
                    val        = val ^ pred;
                    *coded_val = val;
                }
                cbp |= val << (5 - k);

                vc1_decode_i_block(v, v->block[v->cur_blk_idx][block_map[k]], k, val, (k < 4) ? v->codingset : v->codingset2);

                if (CONFIG_GRAY && k > 3 && (s->avctx->flags & AV_CODEC_FLAG_GRAY))
                    continue;
                v->vc1dsp.vc1_inv_trans_8x8(v->block[v->cur_blk_idx][block_map[k]]);
            }

            if (v->overlap && v->pq >= 9) {
                ff_vc1_i_overlap_filter(v);
                if (v->rangeredfrm)
                    for (k = 0; k < 6; k++)
                        for (j = 0; j < 64; j++)
                            v->block[v->cur_blk_idx][block_map[k]][j] *= 2;
                vc1_put_blocks_clamped(v, 1);
            } else {
                if (v->rangeredfrm)
                    for (k = 0; k < 6; k++)
                        for (j = 0; j < 64; j++)
                            v->block[v->cur_blk_idx][block_map[k]][j] = (v->block[v->cur_blk_idx][block_map[k]][j] - 64) * 2;
                vc1_put_blocks_clamped(v, 0);
            }

            if (v->s.loop_filter)
                ff_vc1_i_loop_filter(v);

            if (get_bits_left(&s->gb) < 0) {
                ff_er_add_slice(&s->er, 0, 0, s->mb_x, s->mb_y, ER_MB_ERROR);
                av_log(s->avctx, AV_LOG_ERROR, "Bits overconsumption: %i > %i\n",
                       get_bits_count(&s->gb), s->gb.size_in_bits);
                return;
            }

            v->topleft_blk_idx = (v->topleft_blk_idx + 1) % (v->end_mb_x + 2);
            v->top_blk_idx = (v->top_blk_idx + 1) % (v->end_mb_x + 2);
            v->left_blk_idx = (v->left_blk_idx + 1) % (v->end_mb_x + 2);
            v->cur_blk_idx = (v->cur_blk_idx + 1) % (v->end_mb_x + 2);
        }

        s->first_slice_line = 0;
    }

    /* This is intentionally mb_height and not end_mb_y - unlike in advanced
     * profile, these only differ are when decoding MSS2 rectangles. */
    ff_er_add_slice(&s->er, 0, 0, s->mb_width - 1, s->mb_height - 1, ER_MB_END);
}

/** Decode blocks of I-frame for advanced profile
 */
static int vc1_decode_i_blocks_adv(VC1Context *v)
{
    int k;
    MpegEncContext *s = &v->s;
    int cbp, val;
    uint8_t *coded_val;
    int mb_pos;
    int mquant;
    int mqdiff;
    GetBitContext *gb = &s->gb;

    if (get_bits_left(gb) <= 1)
        return AVERROR_INVALIDDATA;

    /* select coding mode used for VLC tables selection */
    switch (v->y_ac_table_index) {
    case 0:
        v->codingset = (v->pqindex <= 8) ? CS_HIGH_RATE_INTRA : CS_LOW_MOT_INTRA;
        break;
    case 1:
        v->codingset = CS_HIGH_MOT_INTRA;
        break;
    case 2:
        v->codingset = CS_MID_RATE_INTRA;
        break;
    }

    switch (v->c_ac_table_index) {
    case 0:
        v->codingset2 = (v->pqindex <= 8) ? CS_HIGH_RATE_INTER : CS_LOW_MOT_INTER;
        break;
    case 1:
        v->codingset2 = CS_HIGH_MOT_INTER;
        break;
    case 2:
        v->codingset2 = CS_MID_RATE_INTER;
        break;
    }

    // do frame decode
    s->mb_x             = s->mb_y = 0;
    s->mb_intra         = 1;
    s->first_slice_line = 1;
    s->mb_y             = s->start_mb_y;
    if (s->start_mb_y) {
        s->mb_x = 0;
        init_block_index(v);
        memset(&s->coded_block[s->block_index[0] - s->b8_stride], 0,
               (1 + s->b8_stride) * sizeof(*s->coded_block));
    }
    for (; s->mb_y < s->end_mb_y; s->mb_y++) {
        s->mb_x = 0;
        init_block_index(v);
        for (;s->mb_x < s->mb_width; s->mb_x++) {
            mquant = v->pq;
            update_block_index(s);
            s->bdsp.clear_blocks(v->block[v->cur_blk_idx][0]);
            mb_pos = s->mb_x + s->mb_y * s->mb_stride;
            s->current_picture.mb_type[mb_pos + v->mb_off]                         = MB_TYPE_INTRA;
            for (int i = 0; i < 4; i++) {
                s->current_picture.motion_val[1][s->block_index[i] + v->blocks_off][0] = 0;
                s->current_picture.motion_val[1][s->block_index[i] + v->blocks_off][1] = 0;
            }

            // do actual MB decoding and displaying
            if (v->fieldtx_is_raw)
                v->fieldtx_plane[mb_pos] = get_bits1(&v->s.gb);
            if (get_bits_left(&v->s.gb) <= 1) {
                ff_er_add_slice(&s->er, 0, s->start_mb_y, s->mb_x, s->mb_y, ER_MB_ERROR);
                return 0;
            }

            cbp = get_vlc2(&v->s.gb, ff_msmp4_mb_i_vlc,
                           MSMP4_MB_INTRA_VLC_BITS, 2);
            if (v->acpred_is_raw)
                v->s.ac_pred = get_bits1(&v->s.gb);
            else
                v->s.ac_pred = v->acpred_plane[mb_pos];

            if (v->condover == CONDOVER_SELECT && v->overflg_is_raw)
                v->over_flags_plane[mb_pos] = get_bits1(&v->s.gb);

            GET_MQUANT();

            s->current_picture.qscale_table[mb_pos] = mquant;
            /* Set DC scale - y and c use the same */
            s->y_dc_scale = s->y_dc_scale_table[FFABS(mquant)];
            s->c_dc_scale = s->c_dc_scale_table[FFABS(mquant)];

            for (k = 0; k < 6; k++) {
                v->mb_type[0][s->block_index[k]] = 1;

                val = ((cbp >> (5 - k)) & 1);

                if (k < 4) {
                    int pred   = vc1_coded_block_pred(&v->s, k, &coded_val);
                    val        = val ^ pred;
                    *coded_val = val;
                }
                cbp |= val << (5 - k);

                v->a_avail = !s->first_slice_line || (k == 2 || k == 3);
                v->c_avail = !!s->mb_x || (k == 1 || k == 3);

                vc1_decode_i_block_adv(v, v->block[v->cur_blk_idx][block_map[k]], k, val,
                                       (k < 4) ? v->codingset : v->codingset2, mquant);

                if (CONFIG_GRAY && k > 3 && (s->avctx->flags & AV_CODEC_FLAG_GRAY))
                    continue;
                v->vc1dsp.vc1_inv_trans_8x8(v->block[v->cur_blk_idx][block_map[k]]);
            }

            if (v->overlap && (v->pq >= 9 || v->condover != CONDOVER_NONE))
                ff_vc1_i_overlap_filter(v);
            vc1_put_blocks_clamped(v, 1);
            if (v->s.loop_filter)
                ff_vc1_i_loop_filter(v);

            if (get_bits_left(&s->gb) < 0) {
                // TODO: may need modification to handle slice coding
                ff_er_add_slice(&s->er, 0, s->start_mb_y, s->mb_x, s->mb_y, ER_MB_ERROR);
                av_log(s->avctx, AV_LOG_ERROR, "Bits overconsumption: %i > %i\n",
                       get_bits_count(&s->gb), s->gb.size_in_bits);
                return 0;
            }
            inc_blk_idx(v->topleft_blk_idx);
            inc_blk_idx(v->top_blk_idx);
            inc_blk_idx(v->left_blk_idx);
            inc_blk_idx(v->cur_blk_idx);
        }
        s->first_slice_line = 0;
    }

    ff_er_add_slice(&s->er, 0, s->start_mb_y << v->field_mode, s->mb_width - 1,
                    (s->end_mb_y << v->field_mode) - 1, ER_MB_END);
    return 0;
}

static void vc1_decode_p_blocks(VC1Context *v)
{
    MpegEncContext *s = &v->s;
    int apply_loop_filter;

    /* select coding mode used for VLC tables selection */
    switch (v->c_ac_table_index) {
    case 0:
        v->codingset = (v->pqindex <= 8) ? CS_HIGH_RATE_INTRA : CS_LOW_MOT_INTRA;
        break;
    case 1:
        v->codingset = CS_HIGH_MOT_INTRA;
        break;
    case 2:
        v->codingset = CS_MID_RATE_INTRA;
        break;
    }

    switch (v->c_ac_table_index) {
    case 0:
        v->codingset2 = (v->pqindex <= 8) ? CS_HIGH_RATE_INTER : CS_LOW_MOT_INTER;
        break;
    case 1:
        v->codingset2 = CS_HIGH_MOT_INTER;
        break;
    case 2:
        v->codingset2 = CS_MID_RATE_INTER;
        break;
    }

    apply_loop_filter   = s->loop_filter && !(s->avctx->skip_loop_filter >= AVDISCARD_NONKEY);
    s->first_slice_line = 1;
    memset(v->cbp_base, 0, sizeof(v->cbp_base[0]) * 3 * s->mb_stride);
    for (s->mb_y = s->start_mb_y; s->mb_y < s->end_mb_y; s->mb_y++) {
        s->mb_x = 0;
        init_block_index(v);
        for (; s->mb_x < s->mb_width; s->mb_x++) {
            update_block_index(s);

            if (v->fcm == ILACE_FIELD || (v->fcm == PROGRESSIVE && v->mv_type_is_raw) || v->skip_is_raw)
                if (get_bits_left(&v->s.gb) <= 1) {
                    ff_er_add_slice(&s->er, 0, s->start_mb_y, s->mb_x, s->mb_y, ER_MB_ERROR);
                    return;
                }

            if (v->fcm == ILACE_FIELD) {
                vc1_decode_p_mb_intfi(v);
                if (apply_loop_filter)
                    ff_vc1_p_loop_filter(v);
            } else if (v->fcm == ILACE_FRAME) {
                vc1_decode_p_mb_intfr(v);
                if (apply_loop_filter)
                    ff_vc1_p_intfr_loop_filter(v);
            } else {
                vc1_decode_p_mb(v);
                if (apply_loop_filter)
                    ff_vc1_p_loop_filter(v);
            }
            if (get_bits_left(&s->gb) < 0 || get_bits_count(&s->gb) < 0) {
                // TODO: may need modification to handle slice coding
                ff_er_add_slice(&s->er, 0, s->start_mb_y, s->mb_x, s->mb_y, ER_MB_ERROR);
                av_log(s->avctx, AV_LOG_ERROR, "Bits overconsumption: %i > %i at %ix%i\n",
                       get_bits_count(&s->gb), s->gb.size_in_bits, s->mb_x, s->mb_y);
                return;
            }
            inc_blk_idx(v->topleft_blk_idx);
            inc_blk_idx(v->top_blk_idx);
            inc_blk_idx(v->left_blk_idx);
            inc_blk_idx(v->cur_blk_idx);
        }
        memmove(v->cbp_base,
                v->cbp - s->mb_stride,
                sizeof(v->cbp_base[0]) * 2 * s->mb_stride);
        memmove(v->ttblk_base,
                v->ttblk - s->mb_stride,
                sizeof(v->ttblk_base[0]) * 2 * s->mb_stride);
        memmove(v->is_intra_base,
                v->is_intra - s->mb_stride,
                sizeof(v->is_intra_base[0]) * 2 * s->mb_stride);
        memmove(v->luma_mv_base,
                v->luma_mv - s->mb_stride,
                sizeof(v->luma_mv_base[0]) * 2 * s->mb_stride);
        s->first_slice_line = 0;
    }
    ff_er_add_slice(&s->er, 0, s->start_mb_y << v->field_mode, s->mb_width - 1,
                    (s->end_mb_y << v->field_mode) - 1, ER_MB_END);
}

static void vc1_decode_b_blocks(VC1Context *v)
{
    MpegEncContext *s = &v->s;

    /* select coding mode used for VLC tables selection */
    switch (v->c_ac_table_index) {
    case 0:
        v->codingset = (v->pqindex <= 8) ? CS_HIGH_RATE_INTRA : CS_LOW_MOT_INTRA;
        break;
    case 1:
        v->codingset = CS_HIGH_MOT_INTRA;
        break;
    case 2:
        v->codingset = CS_MID_RATE_INTRA;
        break;
    }

    switch (v->c_ac_table_index) {
    case 0:
        v->codingset2 = (v->pqindex <= 8) ? CS_HIGH_RATE_INTER : CS_LOW_MOT_INTER;
        break;
    case 1:
        v->codingset2 = CS_HIGH_MOT_INTER;
        break;
    case 2:
        v->codingset2 = CS_MID_RATE_INTER;
        break;
    }

    s->first_slice_line = 1;
    for (s->mb_y = s->start_mb_y; s->mb_y < s->end_mb_y; s->mb_y++) {
        s->mb_x = 0;
        init_block_index(v);
        for (; s->mb_x < s->mb_width; s->mb_x++) {
            update_block_index(s);

            if (v->fcm == ILACE_FIELD || v->skip_is_raw || v->dmb_is_raw)
                if (get_bits_left(&v->s.gb) <= 1) {
                    ff_er_add_slice(&s->er, 0, s->start_mb_y, s->mb_x, s->mb_y, ER_MB_ERROR);
                    return;
                }

            if (v->fcm == ILACE_FIELD) {
                vc1_decode_b_mb_intfi(v);
                if (v->s.loop_filter)
                    ff_vc1_b_intfi_loop_filter(v);
            } else if (v->fcm == ILACE_FRAME) {
                vc1_decode_b_mb_intfr(v);
                if (v->s.loop_filter)
                    ff_vc1_p_intfr_loop_filter(v);
            } else {
                vc1_decode_b_mb(v);
                if (v->s.loop_filter)
                    ff_vc1_i_loop_filter(v);
            }
            if (get_bits_left(&s->gb) < 0 || get_bits_count(&s->gb) < 0) {
                // TODO: may need modification to handle slice coding
                ff_er_add_slice(&s->er, 0, s->start_mb_y, s->mb_x, s->mb_y, ER_MB_ERROR);
                av_log(s->avctx, AV_LOG_ERROR, "Bits overconsumption: %i > %i at %ix%i\n",
                       get_bits_count(&s->gb), s->gb.size_in_bits, s->mb_x, s->mb_y);
                return;
            }
        }
        memmove(v->cbp_base,
                v->cbp - s->mb_stride,
                sizeof(v->cbp_base[0]) * 2 * s->mb_stride);
        memmove(v->ttblk_base,
                v->ttblk - s->mb_stride,
                sizeof(v->ttblk_base[0]) * 2 * s->mb_stride);
        memmove(v->is_intra_base,
                v->is_intra - s->mb_stride,
                sizeof(v->is_intra_base[0]) * 2 * s->mb_stride);
        s->first_slice_line = 0;
    }
    ff_er_add_slice(&s->er, 0, s->start_mb_y << v->field_mode, s->mb_width - 1,
                    (s->end_mb_y << v->field_mode) - 1, ER_MB_END);
}

static void vc1_decode_skip_blocks(VC1Context *v)
{
    MpegEncContext *s = &v->s;

    if (!v->s.last_picture.f->data[0])
        return;

    ff_er_add_slice(&s->er, 0, s->start_mb_y, s->mb_width - 1, s->end_mb_y - 1, ER_MB_END);
    s->first_slice_line = 1;
    for (s->mb_y = s->start_mb_y; s->mb_y < s->end_mb_y; s->mb_y++) {
        s->mb_x = 0;
        init_block_index(v);
        update_block_index(s);
        memcpy(s->dest[0], s->last_picture.f->data[0] + s->mb_y * 16 * s->linesize,   s->linesize   * 16);
        memcpy(s->dest[1], s->last_picture.f->data[1] + s->mb_y *  8 * s->uvlinesize, s->uvlinesize *  8);
        memcpy(s->dest[2], s->last_picture.f->data[2] + s->mb_y *  8 * s->uvlinesize, s->uvlinesize *  8);
        s->first_slice_line = 0;
    }
}

void ff_vc1_decode_blocks(VC1Context *v)
{

    v->s.esc3_level_length = 0;
    if (v->x8_type) {
        ff_intrax8_decode_picture(&v->x8, &v->s.current_picture,
                                  &v->s.gb, &v->s.mb_x, &v->s.mb_y,
                                  2 * v->pq + v->halfpq, v->pq * !v->pquantizer,
                                  v->s.loop_filter, v->s.low_delay);

        ff_er_add_slice(&v->s.er, 0, 0,
                        (v->s.mb_x >> 1) - 1, (v->s.mb_y >> 1) - 1,
                        ER_MB_END);
    } else {
        v->cur_blk_idx     =  0;
        v->left_blk_idx    = -1;
        v->topleft_blk_idx =  1;
        v->top_blk_idx     =  2;
        switch (v->s.pict_type) {
        case AV_PICTURE_TYPE_I:
            if (v->profile == PROFILE_ADVANCED)
                vc1_decode_i_blocks_adv(v);
            else
                vc1_decode_i_blocks(v);
            break;
        case AV_PICTURE_TYPE_P:
            if (v->p_frame_skipped)
                vc1_decode_skip_blocks(v);
            else
                vc1_decode_p_blocks(v);
            break;
        case AV_PICTURE_TYPE_B:
            if (v->bi_type) {
                if (v->profile == PROFILE_ADVANCED)
                    vc1_decode_i_blocks_adv(v);
                else
                    vc1_decode_i_blocks(v);
            } else
                vc1_decode_b_blocks(v);
            break;
        }
    }
}