PeerStreamer

/*

 * Chinese AVS video (AVS1-P2, JiZhun profile) decoder.

 * Copyright (c) 2006  Stefan Gehrer <stefan.gehrer@gmx.de>

 *

 * 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 St, Fifth Floor, Boston, MA  02110-1301  USA

 */

/**

 * @file cavs.c

 * Chinese AVS video (AVS1-P2, JiZhun profile) decoder

 * @author Stefan Gehrer <stefan.gehrer@gmx.de>

 */

#include "avcodec.h"

#include "bitstream.h"

#include "golomb.h"

#include "mpegvideo.h"

#include "cavsdata.h"

#ifdef CONFIG_CAVS_DECODER

typedef struct {

    MpegEncContext s;

    Picture picture; ///< currently decoded frame

    Picture DPB[2];  ///< reference frames

    int dist[2];     ///< temporal distances from current frame to ref frames

    int profile, level;

    int aspect_ratio;

    int mb_width, mb_height;

    int pic_type;

    int progressive;

    int pic_structure;

    int skip_mode_flag; ///< select between skip_count or one skip_flag per MB

    int loop_filter_disable;

    int alpha_offset, beta_offset;

    int ref_flag;

    int mbx, mby;      ///< macroblock coordinates

    int flags;         ///< availability flags of neighbouring macroblocks

    int stc;           ///< last start code

    uint8_t *cy, *cu, *cv; ///< current MB sample pointers

    int left_qp;

    uint8_t *top_qp;

    /** mv motion vector cache

       0:    D3  B2  B3  C2

       4:    A1  X0  X1   -

       8:    A3  X2  X3   -

       X are the vectors in the current macroblock (5,6,9,10)

       A is the macroblock to the left (4,8)

       B is the macroblock to the top (1,2)

       C is the macroblock to the top-right (3)

       D is the macroblock to the top-left (0)

       the same is repeated for backward motion vectors */

    vector_t mv[2*4*3];

    vector_t *top_mv[2];

    vector_t *col_mv;

    /** luma pred mode cache

       0:    --  B2  B3

       3:    A1  X0  X1

       6:    A3  X2  X3   */

    int pred_mode_Y[3*3];

    int *top_pred_Y;

    int l_stride, c_stride;

    int luma_scan[4];

    int qp;

    int qp_fixed;

    int cbp;

    ScanTable scantable;

    /** intra prediction is done with un-deblocked samples

     they are saved here before deblocking the MB  */

    uint8_t *top_border_y, *top_border_u, *top_border_v;

    uint8_t left_border_y[26], left_border_u[10], left_border_v[10];

    uint8_t intern_border_y[26];

    uint8_t topleft_border_y, topleft_border_u, topleft_border_v;

    void (*intra_pred_l[8])(uint8_t *d,uint8_t *top,uint8_t *left,int stride);

    void (*intra_pred_c[7])(uint8_t *d,uint8_t *top,uint8_t *left,int stride);

    uint8_t *col_type_base;

    uint8_t *col_type;

    /* scaling factors for MV prediction */

    int sym_factor;    ///< for scaling in symmetrical B block

    int direct_den[2]; ///< for scaling in direct B block

    int scale_den[2];  ///< for scaling neighbouring MVs

    int got_keyframe;

    DCTELEM *block;

} AVSContext;

/*****************************************************************************

 *

 * in-loop deblocking filter

 *

 ****************************************************************************/

static inline int get_bs(vector_t *mvP, vector_t *mvQ, int b) {

    if((mvP->ref == REF_INTRA) || (mvQ->ref == REF_INTRA))

        return 2;

    if( (abs(mvP->x - mvQ->x) >= 4) ||  (abs(mvP->y - mvQ->y) >= 4) )

        return 1;

    if(b){

        mvP += MV_BWD_OFFS;

        mvQ += MV_BWD_OFFS;

        if( (abs(mvP->x - mvQ->x) >= 4) ||  (abs(mvP->y - mvQ->y) >= 4) )

            return 1;

    }else{

        if(mvP->ref != mvQ->ref)

            return 1;

    }

    return 0;

}

#define SET_PARAMS                                            \

    alpha = alpha_tab[av_clip(qp_avg + h->alpha_offset,0,63)];   \

    beta  =  beta_tab[av_clip(qp_avg + h->beta_offset, 0,63)];   \

    tc    =    tc_tab[av_clip(qp_avg + h->alpha_offset,0,63)];

/**

 * in-loop deblocking filter for a single macroblock

 *

 * boundary strength (bs) mapping:

 *

 * --4---5--

 * 0   2   |

 * | 6 | 7 |

 * 1   3   |

 * ---------

 *

 */

static void filter_mb(AVSContext *h, enum mb_t mb_type) {

    DECLARE_ALIGNED_8(uint8_t, bs[8]);

    int qp_avg, alpha, beta, tc;

    int i;

    /* save un-deblocked lines */

    h->topleft_border_y = h->top_border_y[h->mbx*16+15];

    h->topleft_border_u = h->top_border_u[h->mbx*10+8];

    h->topleft_border_v = h->top_border_v[h->mbx*10+8];

    memcpy(&h->top_border_y[h->mbx*16], h->cy + 15* h->l_stride,16);

    memcpy(&h->top_border_u[h->mbx*10+1], h->cu +  7* h->c_stride,8);

    memcpy(&h->top_border_v[h->mbx*10+1], h->cv +  7* h->c_stride,8);

    for(i=0;i<8;i++) {

        h->left_border_y[i*2+1] = *(h->cy + 15 + (i*2+0)*h->l_stride);

        h->left_border_y[i*2+2] = *(h->cy + 15 + (i*2+1)*h->l_stride);

        h->left_border_u[i+1] = *(h->cu + 7 + i*h->c_stride);

        h->left_border_v[i+1] = *(h->cv + 7 + i*h->c_stride);

    }

    if(!h->loop_filter_disable) {

        /* determine bs */

        if(mb_type == I_8X8)

            *((uint64_t *)bs) = 0x0202020202020202ULL;

        else{

            *((uint64_t *)bs) = 0;

            if(partition_flags[mb_type] & SPLITV){

                bs[2] = get_bs(&h->mv[MV_FWD_X0], &h->mv[MV_FWD_X1], mb_type > P_8X8);

                bs[3] = get_bs(&h->mv[MV_FWD_X2], &h->mv[MV_FWD_X3], mb_type > P_8X8);

            }

            if(partition_flags[mb_type] & SPLITH){

                bs[6] = get_bs(&h->mv[MV_FWD_X0], &h->mv[MV_FWD_X2], mb_type > P_8X8);

                bs[7] = get_bs(&h->mv[MV_FWD_X1], &h->mv[MV_FWD_X3], mb_type > P_8X8);

            }

            bs[0] = get_bs(&h->mv[MV_FWD_A1], &h->mv[MV_FWD_X0], mb_type > P_8X8);

            bs[1] = get_bs(&h->mv[MV_FWD_A3], &h->mv[MV_FWD_X2], mb_type > P_8X8);

            bs[4] = get_bs(&h->mv[MV_FWD_B2], &h->mv[MV_FWD_X0], mb_type > P_8X8);

            bs[5] = get_bs(&h->mv[MV_FWD_B3], &h->mv[MV_FWD_X1], mb_type > P_8X8);

        }

        if( *((uint64_t *)bs) ) {

            if(h->flags & A_AVAIL) {

                qp_avg = (h->qp + h->left_qp + 1) >> 1;

                SET_PARAMS;

                h->s.dsp.cavs_filter_lv(h->cy,h->l_stride,alpha,beta,tc,bs[0],bs[1]);

                h->s.dsp.cavs_filter_cv(h->cu,h->c_stride,alpha,beta,tc,bs[0],bs[1]);

                h->s.dsp.cavs_filter_cv(h->cv,h->c_stride,alpha,beta,tc,bs[0],bs[1]);

            }

            qp_avg = h->qp;

            SET_PARAMS;

            h->s.dsp.cavs_filter_lv(h->cy + 8,h->l_stride,alpha,beta,tc,bs[2],bs[3]);

            h->s.dsp.cavs_filter_lh(h->cy + 8*h->l_stride,h->l_stride,alpha,beta,tc,

                           bs[6],bs[7]);

            if(h->flags & B_AVAIL) {

                qp_avg = (h->qp + h->top_qp[h->mbx] + 1) >> 1;

                SET_PARAMS;

                h->s.dsp.cavs_filter_lh(h->cy,h->l_stride,alpha,beta,tc,bs[4],bs[5]);

                h->s.dsp.cavs_filter_ch(h->cu,h->c_stride,alpha,beta,tc,bs[4],bs[5]);

                h->s.dsp.cavs_filter_ch(h->cv,h->c_stride,alpha,beta,tc,bs[4],bs[5]);

            }

        }

    }

    h->left_qp = h->qp;

    h->top_qp[h->mbx] = h->qp;

}

#undef SET_PARAMS

/*****************************************************************************

 *

 * spatial intra prediction

 *

 ****************************************************************************/

static inline void load_intra_pred_luma(AVSContext *h, uint8_t *top,

                                        uint8_t **left, int block) {

    int i;

    switch(block) {

    case 0:

        *left = h->left_border_y;

        h->left_border_y[0] = h->left_border_y[1];

        memset(&h->left_border_y[17],h->left_border_y[16],9);

        memcpy(&top[1],&h->top_border_y[h->mbx*16],16);

        top[17] = top[16];

        top[0] = top[1];

        if((h->flags & A_AVAIL) && (h->flags & B_AVAIL))

            h->left_border_y[0] = top[0] = h->topleft_border_y;

        break;

    case 1:

        *left = h->intern_border_y;

        for(i=0;i<8;i++)

            h->intern_border_y[i+1] = *(h->cy + 7 + i*h->l_stride);

        memset(&h->intern_border_y[9],h->intern_border_y[8],9);

        h->intern_border_y[0] = h->intern_border_y[1];

        memcpy(&top[1],&h->top_border_y[h->mbx*16+8],8);

        if(h->flags & C_AVAIL)

            memcpy(&top[9],&h->top_border_y[(h->mbx + 1)*16],8);

        else

            memset(&top[9],top[8],9);

        top[17] = top[16];

        top[0] = top[1];

        if(h->flags & B_AVAIL)

            h->intern_border_y[0] = top[0] = h->top_border_y[h->mbx*16+7];

        break;

    case 2:

        *left = &h->left_border_y[8];

        memcpy(&top[1],h->cy + 7*h->l_stride,16);

        top[17] = top[16];

        top[0] = top[1];

        if(h->flags & A_AVAIL)

            top[0] = h->left_border_y[8];

        break;

    case 3:

        *left = &h->intern_border_y[8];

        for(i=0;i<8;i++)

            h->intern_border_y[i+9] = *(h->cy + 7 + (i+8)*h->l_stride);

        memset(&h->intern_border_y[17],h->intern_border_y[16],9);

        memcpy(&top[0],h->cy + 7 + 7*h->l_stride,9);

        memset(&top[9],top[8],9);

        break;

    }

}

static void intra_pred_vert(uint8_t *d,uint8_t *top,uint8_t *left,int stride) {

    int y;

    uint64_t a = unaligned64(&top[1]);

    for(y=0;y<8;y++) {

        *((uint64_t *)(d+y*stride)) = a;

    }

}

static void intra_pred_horiz(uint8_t *d,uint8_t *top,uint8_t *left,int stride) {

    int y;

    uint64_t a;

    for(y=0;y<8;y++) {

        a = left[y+1] * 0x0101010101010101ULL;

        *((uint64_t *)(d+y*stride)) = a;

    }

}

static void intra_pred_dc_128(uint8_t *d,uint8_t *top,uint8_t *left,int stride) {

    int y;

    uint64_t a = 0x8080808080808080ULL;

    for(y=0;y<8;y++)

        *((uint64_t *)(d+y*stride)) = a;

}

static void intra_pred_plane(uint8_t *d,uint8_t *top,uint8_t *left,int stride) {

    int x,y,ia;

    int ih = 0;

    int iv = 0;

    uint8_t *cm = ff_cropTbl + MAX_NEG_CROP;

    for(x=0; x<4; x++) {

        ih += (x+1)*(top[5+x]-top[3-x]);

        iv += (x+1)*(left[5+x]-left[3-x]);

    }

    ia = (top[8]+left[8])<<4;

    ih = (17*ih+16)>>5;

    iv = (17*iv+16)>>5;

    for(y=0; y<8; y++)

        for(x=0; x<8; x++)

            d[y*stride+x] = cm[(ia+(x-3)*ih+(y-3)*iv+16)>>5];

}

#define LOWPASS(ARRAY,INDEX)                                            \

    (( ARRAY[(INDEX)-1] + 2*ARRAY[(INDEX)] + ARRAY[(INDEX)+1] + 2) >> 2)

static void intra_pred_lp(uint8_t *d,uint8_t *top,uint8_t *left,int stride) {

    int x,y;

    for(y=0; y<8; y++)

        for(x=0; x<8; x++)

            d[y*stride+x] = (LOWPASS(top,x+1) + LOWPASS(left,y+1)) >> 1;

}

static void intra_pred_down_left(uint8_t *d,uint8_t *top,uint8_t *left,int stride) {

    int x,y;

    for(y=0; y<8; y++)

        for(x=0; x<8; x++)

            d[y*stride+x] = (LOWPASS(top,x+y+2) + LOWPASS(left,x+y+2)) >> 1;

}

static void intra_pred_down_right(uint8_t *d,uint8_t *top,uint8_t *left,int stride) {

    int x,y;

    for(y=0; y<8; y++)

        for(x=0; x<8; x++)

            if(x==y)

                d[y*stride+x] = (left[1]+2*top[0]+top[1]+2)>>2;

            else if(x>y)

                d[y*stride+x] = LOWPASS(top,x-y);

            else

                d[y*stride+x] = LOWPASS(left,y-x);

}

static void intra_pred_lp_left(uint8_t *d,uint8_t *top,uint8_t *left,int stride) {

    int x,y;

    for(y=0; y<8; y++)

        for(x=0; x<8; x++)

            d[y*stride+x] = LOWPASS(left,y+1);

}

static void intra_pred_lp_top(uint8_t *d,uint8_t *top,uint8_t *left,int stride) {

    int x,y;

    for(y=0; y<8; y++)

        for(x=0; x<8; x++)

            d[y*stride+x] = LOWPASS(top,x+1);

}

#undef LOWPASS

static inline void modify_pred(const int_fast8_t *mod_table, int *mode) {

    *mode = mod_table[*mode];

    if(*mode < 0) {

        av_log(NULL, AV_LOG_ERROR, "Illegal intra prediction mode\n");

        *mode = 0;

    }

}

/*****************************************************************************

 *

 * motion compensation

 *

 ****************************************************************************/

static inline void mc_dir_part(AVSContext *h,Picture *pic,int square,

                        int chroma_height,int delta,int list,uint8_t *dest_y,

                        uint8_t *dest_cb,uint8_t *dest_cr,int src_x_offset,

                        int src_y_offset,qpel_mc_func *qpix_op,

                        h264_chroma_mc_func chroma_op,vector_t *mv){

    MpegEncContext * const s = &h->s;

    const int mx= mv->x + src_x_offset*8;

    const int my= mv->y + src_y_offset*8;

    const int luma_xy= (mx&3) + ((my&3)<<2);

    uint8_t * src_y = pic->data[0] + (mx>>2) + (my>>2)*h->l_stride;

    uint8_t * src_cb= pic->data[1] + (mx>>3) + (my>>3)*h->c_stride;

    uint8_t * src_cr= pic->data[2] + (mx>>3) + (my>>3)*h->c_stride;

    int extra_width= 0; //(s->flags&CODEC_FLAG_EMU_EDGE) ? 0 : 16;

    int extra_height= extra_width;

    int emu=0;

    const int full_mx= mx>>2;

    const int full_my= my>>2;

    const int pic_width  = 16*h->mb_width;

    const int pic_height = 16*h->mb_height;

    if(!pic->data[0])

        return;

    if(mx&7) extra_width -= 3;

    if(my&7) extra_height -= 3;

    if(   full_mx < 0-extra_width

          || full_my < 0-extra_height

          || full_mx + 16/*FIXME*/ > pic_width + extra_width

          || full_my + 16/*FIXME*/ > pic_height + extra_height){

        ff_emulated_edge_mc(s->edge_emu_buffer, src_y - 2 - 2*h->l_stride, h->l_stride,

                            16+5, 16+5/*FIXME*/, full_mx-2, full_my-2, pic_width, pic_height);

        src_y= s->edge_emu_buffer + 2 + 2*h->l_stride;

        emu=1;

    }

    qpix_op[luma_xy](dest_y, src_y, h->l_stride); //FIXME try variable height perhaps?

    if(!square){

        qpix_op[luma_xy](dest_y + delta, src_y + delta, h->l_stride);

    }

    if(emu){

        ff_emulated_edge_mc(s->edge_emu_buffer, src_cb, h->c_stride,

                            9, 9/*FIXME*/, (mx>>3), (my>>3), pic_width>>1, pic_height>>1);

        src_cb= s->edge_emu_buffer;

    }

    chroma_op(dest_cb, src_cb, h->c_stride, chroma_height, mx&7, my&7);

    if(emu){

        ff_emulated_edge_mc(s->edge_emu_buffer, src_cr, h->c_stride,

                            9, 9/*FIXME*/, (mx>>3), (my>>3), pic_width>>1, pic_height>>1);

        src_cr= s->edge_emu_buffer;

    }

    chroma_op(dest_cr, src_cr, h->c_stride, chroma_height, mx&7, my&7);

}

static inline void mc_part_std(AVSContext *h,int square,int chroma_height,int delta,

                        uint8_t *dest_y,uint8_t *dest_cb,uint8_t *dest_cr,

                        int x_offset, int y_offset,qpel_mc_func *qpix_put,

                        h264_chroma_mc_func chroma_put,qpel_mc_func *qpix_avg,

                        h264_chroma_mc_func chroma_avg, vector_t *mv){

    qpel_mc_func *qpix_op=  qpix_put;

    h264_chroma_mc_func chroma_op= chroma_put;

    dest_y  += 2*x_offset + 2*y_offset*h->l_stride;

    dest_cb +=   x_offset +   y_offset*h->c_stride;

    dest_cr +=   x_offset +   y_offset*h->c_stride;

    x_offset += 8*h->mbx;

    y_offset += 8*h->mby;

    if(mv->ref >= 0){

        Picture *ref= &h->DPB[mv->ref];

        mc_dir_part(h, ref, square, chroma_height, delta, 0,

                    dest_y, dest_cb, dest_cr, x_offset, y_offset,

                    qpix_op, chroma_op, mv);

        qpix_op=  qpix_avg;

        chroma_op= chroma_avg;

    }

    if((mv+MV_BWD_OFFS)->ref >= 0){

        Picture *ref= &h->DPB[0];

        mc_dir_part(h, ref, square, chroma_height, delta, 1,

                    dest_y, dest_cb, dest_cr, x_offset, y_offset,

                    qpix_op, chroma_op, mv+MV_BWD_OFFS);

    }

}

static void inter_pred(AVSContext *h, enum mb_t mb_type) {

    if(partition_flags[mb_type] == 0){ // 16x16

        mc_part_std(h, 1, 8, 0, h->cy, h->cu, h->cv, 0, 0,

                h->s.dsp.put_cavs_qpel_pixels_tab[0],

                h->s.dsp.put_h264_chroma_pixels_tab[0],

                h->s.dsp.avg_cavs_qpel_pixels_tab[0],

                h->s.dsp.avg_h264_chroma_pixels_tab[0],&h->mv[MV_FWD_X0]);

    }else{

        mc_part_std(h, 1, 4, 0, h->cy, h->cu, h->cv, 0, 0,

                h->s.dsp.put_cavs_qpel_pixels_tab[1],

                h->s.dsp.put_h264_chroma_pixels_tab[1],

                h->s.dsp.avg_cavs_qpel_pixels_tab[1],

                h->s.dsp.avg_h264_chroma_pixels_tab[1],&h->mv[MV_FWD_X0]);

        mc_part_std(h, 1, 4, 0, h->cy, h->cu, h->cv, 4, 0,

                h->s.dsp.put_cavs_qpel_pixels_tab[1],

                h->s.dsp.put_h264_chroma_pixels_tab[1],

                h->s.dsp.avg_cavs_qpel_pixels_tab[1],

                h->s.dsp.avg_h264_chroma_pixels_tab[1],&h->mv[MV_FWD_X1]);

        mc_part_std(h, 1, 4, 0, h->cy, h->cu, h->cv, 0, 4,

                h->s.dsp.put_cavs_qpel_pixels_tab[1],

                h->s.dsp.put_h264_chroma_pixels_tab[1],

                h->s.dsp.avg_cavs_qpel_pixels_tab[1],

                h->s.dsp.avg_h264_chroma_pixels_tab[1],&h->mv[MV_FWD_X2]);

        mc_part_std(h, 1, 4, 0, h->cy, h->cu, h->cv, 4, 4,

                h->s.dsp.put_cavs_qpel_pixels_tab[1],

                h->s.dsp.put_h264_chroma_pixels_tab[1],

                h->s.dsp.avg_cavs_qpel_pixels_tab[1],

                h->s.dsp.avg_h264_chroma_pixels_tab[1],&h->mv[MV_FWD_X3]);

    }

    /* set intra prediction modes to default values */

    h->pred_mode_Y[3] =  h->pred_mode_Y[6] = INTRA_L_LP;

    h->top_pred_Y[h->mbx*2+0] = h->top_pred_Y[h->mbx*2+1] = INTRA_L_LP;

}

/*****************************************************************************

 *

 * motion vector prediction

 *

 ****************************************************************************/

static inline void set_mvs(vector_t *mv, enum block_t size) {

    switch(size) {

    case BLK_16X16:

        mv[MV_STRIDE  ] = mv[0];

        mv[MV_STRIDE+1] = mv[0];

    case BLK_16X8:

        mv[1] = mv[0];

        break;

    case BLK_8X16:

        mv[MV_STRIDE] = mv[0];

        break;

    }

}

static inline void store_mvs(AVSContext *h) {

    h->col_mv[(h->mby*h->mb_width + h->mbx)*4 + 0] = h->mv[MV_FWD_X0];

    h->col_mv[(h->mby*h->mb_width + h->mbx)*4 + 1] = h->mv[MV_FWD_X1];

    h->col_mv[(h->mby*h->mb_width + h->mbx)*4 + 2] = h->mv[MV_FWD_X2];

    h->col_mv[(h->mby*h->mb_width + h->mbx)*4 + 3] = h->mv[MV_FWD_X3];

}

static inline void scale_mv(AVSContext *h, int *d_x, int *d_y, vector_t *src, int distp) {

    int den = h->scale_den[src->ref];

    *d_x = (src->x*distp*den + 256 + (src->x>>31)) >> 9;

    *d_y = (src->y*distp*den + 256 + (src->y>>31)) >> 9;

}

static inline void mv_pred_median(AVSContext *h, vector_t *mvP, vector_t *mvA, vector_t *mvB, vector_t *mvC) {

    int ax, ay, bx, by, cx, cy;

    int len_ab, len_bc, len_ca, len_mid;

    /* scale candidates according to their temporal span */

    scale_mv(h, &ax, &ay, mvA, mvP->dist);

    scale_mv(h, &bx, &by, mvB, mvP->dist);

    scale_mv(h, &cx, &cy, mvC, mvP->dist);

    /* find the geometrical median of the three candidates */

    len_ab = abs(ax - bx) + abs(ay - by);

    len_bc = abs(bx - cx) + abs(by - cy);

    len_ca = abs(cx - ax) + abs(cy - ay);

    len_mid = mid_pred(len_ab, len_bc, len_ca);

    if(len_mid == len_ab) {

        mvP->x = cx;

        mvP->y = cy;

    } else if(len_mid == len_bc) {

        mvP->x = ax;

        mvP->y = ay;

    } else {

        mvP->x = bx;

        mvP->y = by;

    }

}

static inline void mv_pred_direct(AVSContext *h, vector_t *pmv_fw,

                                  vector_t *col_mv) {

    vector_t *pmv_bw = pmv_fw + MV_BWD_OFFS;

    int den = h->direct_den[col_mv->ref];

    int m = col_mv->x >> 31;

    pmv_fw->dist = h->dist[1];

    pmv_bw->dist = h->dist[0];

    pmv_fw->ref = 1;

    pmv_bw->ref = 0;

    /* scale the co-located motion vector according to its temporal span */

    pmv_fw->x = (((den+(den*col_mv->x*pmv_fw->dist^m)-m-1)>>14)^m)-m;

    pmv_bw->x = m-(((den+(den*col_mv->x*pmv_bw->dist^m)-m-1)>>14)^m);

    m = col_mv->y >> 31;

    pmv_fw->y = (((den+(den*col_mv->y*pmv_fw->dist^m)-m-1)>>14)^m)-m;

    pmv_bw->y = m-(((den+(den*col_mv->y*pmv_bw->dist^m)-m-1)>>14)^m);

}

static inline void mv_pred_sym(AVSContext *h, vector_t *src, enum block_t size) {

    vector_t *dst = src + MV_BWD_OFFS;

    /* backward mv is the scaled and negated forward mv */

    dst->x = -((src->x * h->sym_factor + 256) >> 9);

    dst->y = -((src->y * h->sym_factor + 256) >> 9);

    dst->ref = 0;

    dst->dist = h->dist[0];

    set_mvs(dst, size);

}

static void mv_pred(AVSContext *h, enum mv_loc_t nP, enum mv_loc_t nC,

                    enum mv_pred_t mode, enum block_t size, int ref) {

    vector_t *mvP = &h->mv[nP];

    vector_t *mvA = &h->mv[nP-1];

    vector_t *mvB = &h->mv[nP-4];

    vector_t *mvC = &h->mv[nC];

    const vector_t *mvP2 = NULL;

    mvP->ref = ref;

    mvP->dist = h->dist[mvP->ref];

    if(mvC->ref == NOT_AVAIL)

        mvC = &h->mv[nP-5]; // set to top-left (mvD)

    if((mode == MV_PRED_PSKIP) &&

       ((mvA->ref == NOT_AVAIL) || (mvB->ref == NOT_AVAIL) ||

           ((mvA->x | mvA->y | mvA->ref) == 0)  ||

           ((mvB->x | mvB->y | mvB->ref) == 0) )) {

        mvP2 = &un_mv;

    /* if there is only one suitable candidate, take it */

    } else if((mvA->ref >= 0) && (mvB->ref < 0) && (mvC->ref < 0)) {

        mvP2= mvA;

    } else if((mvA->ref < 0) && (mvB->ref >= 0) && (mvC->ref < 0)) {

        mvP2= mvB;

    } else if((mvA->ref < 0) && (mvB->ref < 0) && (mvC->ref >= 0)) {

        mvP2= mvC;

    } else if(mode == MV_PRED_LEFT     && mvA->ref == ref){

        mvP2= mvA;

    } else if(mode == MV_PRED_TOP      && mvB->ref == ref){

        mvP2= mvB;

    } else if(mode == MV_PRED_TOPRIGHT && mvC->ref == ref){

        mvP2= mvC;

    }

    if(mvP2){

        mvP->x = mvP2->x;

        mvP->y = mvP2->y;

    }else

        mv_pred_median(h, mvP, mvA, mvB, mvC);

    if(mode < MV_PRED_PSKIP) {

        mvP->x += get_se_golomb(&h->s.gb);

        mvP->y += get_se_golomb(&h->s.gb);

    }

    set_mvs(mvP,size);

}

/*****************************************************************************

 *

 * residual data decoding

 *

 ****************************************************************************/

/** kth-order exponential golomb code */

static inline int get_ue_code(GetBitContext *gb, int order) {

    if(order) {

        int ret = get_ue_golomb(gb) << order;

        return ret + get_bits(gb,order);

    }

    return get_ue_golomb(gb);

}

/**

 * decode coefficients from one 8x8 block, dequantize, inverse transform

 *  and add them to sample block

 * @param r pointer to 2D VLC table

 * @param esc_golomb_order escape codes are k-golomb with this order k

 * @param qp quantizer

 * @param dst location of sample block

 * @param stride line stride in frame buffer

 */

static int decode_residual_block(AVSContext *h, GetBitContext *gb,

                                 const residual_vlc_t *r, int esc_golomb_order,

                                 int qp, uint8_t *dst, int stride) {

    int i,pos = -1;

    int level_code, esc_code, level, run, mask;

    int level_buf[64];

    int run_buf[64];

    int dqm = dequant_mul[qp];

    int dqs = dequant_shift[qp];

    int dqa = 1 << (dqs - 1);

    const uint8_t *scantab = h->scantable.permutated;

    DCTELEM *block = h->block;

    for(i=0;i<65;i++) {

        level_code = get_ue_code(gb,r->golomb_order);

        if(level_code >= ESCAPE_CODE) {

            run = ((level_code - ESCAPE_CODE) >> 1) + 1;

            esc_code = get_ue_code(gb,esc_golomb_order);

            level = esc_code + (run > r->max_run ? 1 : r->level_add[run]);

            while(level > r->inc_limit)

                r++;

            mask = -(level_code & 1);

            level = (level^mask) - mask;

        } else {

            level = r->rltab[level_code][0];

            if(!level) //end of block signal

                break;

            run   = r->rltab[level_code][1];

            r += r->rltab[level_code][2];

        }

        level_buf[i] = level;

        run_buf[i] = run;

    }

    /* inverse scan and dequantization */

    while(--i >= 0){

        pos += run_buf[i];

        if(pos > 63) {

            av_log(h->s.avctx, AV_LOG_ERROR,

                   "position out of block bounds at pic %d MB(%d,%d)\n",

                   h->picture.poc, h->mbx, h->mby);

            return -1;

        }

        block[scantab[pos]] = (level_buf[i]*dqm + dqa) >> dqs;

    }

    h->s.dsp.cavs_idct8_add(dst,block,stride);

    return 0;

}

static inline void decode_residual_chroma(AVSContext *h) {

    if(h->cbp & (1<<4))

        decode_residual_block(h,&h->s.gb,chroma_2dvlc,0, chroma_qp[h->qp],

                              h->cu,h->c_stride);

    if(h->cbp & (1<<5))

        decode_residual_block(h,&h->s.gb,chroma_2dvlc,0, chroma_qp[h->qp],

                              h->cv,h->c_stride);

}

static inline int decode_residual_inter(AVSContext *h) {

    int block;

    /* get coded block pattern */

    int cbp= get_ue_golomb(&h->s.gb);

    if(cbp > 63){

        av_log(h->s.avctx, AV_LOG_ERROR, "illegal inter cbp\n");

        return -1;

    }

    h->cbp = cbp_tab[cbp][1];

    /* get quantizer */

    if(h->cbp && !h->qp_fixed)

        h->qp = (h->qp + get_se_golomb(&h->s.gb)) & 63;

    for(block=0;block<4;block++)

        if(h->cbp & (1<<block))

            decode_residual_block(h,&h->s.gb,inter_2dvlc,0,h->qp,

                                  h->cy + h->luma_scan[block], h->l_stride);

    decode_residual_chroma(h);

    return 0;

}

/*****************************************************************************

 *

 * macroblock level

 *

 ****************************************************************************/

/**

 * initialise predictors for motion vectors and intra prediction

 */

static inline void init_mb(AVSContext *h) {

    int i;

    /* copy predictors from top line (MB B and C) into cache */

    for(i=0;i<3;i++) {

        h->mv[MV_FWD_B2+i] = h->top_mv[0][h->mbx*2+i];

        h->mv[MV_BWD_B2+i] = h->top_mv[1][h->mbx*2+i];

    }

    h->pred_mode_Y[1] = h->top_pred_Y[h->mbx*2+0];

    h->pred_mode_Y[2] = h->top_pred_Y[h->mbx*2+1];

    /* clear top predictors if MB B is not available */

    if(!(h->flags & B_AVAIL)) {

        h->mv[MV_FWD_B2] = un_mv;

        h->mv[MV_FWD_B3] = un_mv;

        h->mv[MV_BWD_B2] = un_mv;

        h->mv[MV_BWD_B3] = un_mv;

        h->pred_mode_Y[1] = h->pred_mode_Y[2] = NOT_AVAIL;

        h->flags &= ~(C_AVAIL|D_AVAIL);

    } else if(h->mbx) {

        h->flags |= D_AVAIL;

    }

    if(h->mbx == h->mb_width-1) //MB C not available

        h->flags &= ~C_AVAIL;

    /* clear top-right predictors if MB C is not available */

    if(!(h->flags & C_AVAIL)) {

        h->mv[MV_FWD_C2] = un_mv;

        h->mv[MV_BWD_C2] = un_mv;

    }

    /* clear top-left predictors if MB D is not available */

    if(!(h->flags & D_AVAIL)) {

        h->mv[MV_FWD_D3] = un_mv;

        h->mv[MV_BWD_D3] = un_mv;

    }

    /* set pointer for co-located macroblock type */

    h->col_type = &h->col_type_base[h->mby*h->mb_width + h->mbx];

}

static inline void check_for_slice(AVSContext *h);

/**

 * save predictors for later macroblocks and increase

 * macroblock address

 * @returns 0 if end of frame is reached, 1 otherwise

 */

static inline int next_mb(AVSContext *h) {

    int i;

    h->flags |= A_AVAIL;

    h->cy += 16;

    h->cu += 8;

    h->cv += 8;

    /* copy mvs as predictors to the left */

    for(i=0;i<=20;i+=4)

        h->mv[i] = h->mv[i+2];

    /* copy bottom mvs from cache to top line */

    h->top_mv[0][h->mbx*2+0] = h->mv[MV_FWD_X2];

    h->top_mv[0][h->mbx*2+1] = h->mv[MV_FWD_X3];

    h->top_mv[1][h->mbx*2+0] = h->mv[MV_BWD_X2];

    h->top_mv[1][h->mbx*2+1] = h->mv[MV_BWD_X3];

    /* next MB address */

    h->mbx++;

    if(h->mbx == h->mb_width) { //new mb line

        h->flags = B_AVAIL|C_AVAIL;

        /* clear left pred_modes */

        h->pred_mode_Y[3] = h->pred_mode_Y[6] = NOT_AVAIL;

        /* clear left mv predictors */

        for(i=0;i<=20;i+=4)

            h->mv[i] = un_mv;

        h->mbx = 0;

        h->mby++;

        /* re-calculate sample pointers */

        h->cy = h->picture.data[0] + h->mby*16*h->l_stride;

        h->cu = h->picture.data[1] + h->mby*8*h->c_stride;

        h->cv = h->picture.data[2] + h->mby*8*h->c_stride;

        if(h->mby == h->mb_height) { //frame end

            return 0;

        } else {

            //check_for_slice(h);

        }

    }

    return 1;

}

static int decode_mb_i(AVSContext *h, int cbp_code) {

    GetBitContext *gb = &h->s.gb;

    int block, pred_mode_uv;

    uint8_t top[18];

    uint8_t *left = NULL;

    uint8_t *d;

    init_mb(h);

    /* get intra prediction modes from stream */

    for(block=0;block<4;block++) {

        int nA,nB,predpred;

        int pos = scan3x3[block];

        nA = h->pred_mode_Y[pos-1];

        nB = h->pred_mode_Y[pos-3];

        predpred = FFMIN(nA,nB);

        if(predpred == NOT_AVAIL) // if either is not available

            predpred = INTRA_L_LP;

        if(!get_bits1(gb)){

            int rem_mode= get_bits(gb, 2);

            predpred = rem_mode + (rem_mode >= predpred);

        }

        h->pred_mode_Y[pos] = predpred;

    }

    pred_mode_uv = get_ue_golomb(gb);

    if(pred_mode_uv > 6) {

        av_log(h->s.avctx, AV_LOG_ERROR, "illegal intra chroma pred mode\n");

        return -1;

    }

    /* save pred modes before they get modified */

    h->pred_mode_Y[3] =  h->pred_mode_Y[5];

    h->pred_mode_Y[6] =  h->pred_mode_Y[8];

    h->top_pred_Y[h->mbx*2+0] = h->pred_mode_Y[7];

    h->top_pred_Y[h->mbx*2+1] = h->pred_mode_Y[8];

    /* modify pred modes according to availability of neighbour samples */

    if(!(h->flags & A_AVAIL)) {

        modify_pred(left_modifier_l, &h->pred_mode_Y[4] );

        modify_pred(left_modifier_l, &h->pred_mode_Y[7] );

        modify_pred(left_modifier_c, &pred_mode_uv );

    }

    if(!(h->flags & B_AVAIL)) {

        modify_pred(top_modifier_l, &h->pred_mode_Y[4] );

        modify_pred(top_modifier_l, &h->pred_mode_Y[5] );

        modify_pred(top_modifier_c, &pred_mode_uv );

    }

    /* get coded block pattern */

    if(h->pic_type == FF_I_TYPE)

        cbp_code = get_ue_golomb(gb);

    if(cbp_code > 63){

        av_log(h->s.avctx, AV_LOG_ERROR, "illegal intra cbp\n");

        return -1;

    }

    h->cbp = cbp_tab[cbp_code][0];

    if(h->cbp && !h->qp_fixed)

        h->qp = (h->qp + get_se_golomb(gb)) & 63; //qp_delta

    /* luma intra prediction interleaved with residual decode/transform/add */

    for(block=0;block<4;block++) {

        d = h->cy + h->luma_scan[block];

        load_intra_pred_luma(h, top, &left, block);

        h->intra_pred_l[h->pred_mode_Y[scan3x3[block]]]

            (d, top, left, h->l_stride);

        if(h->cbp & (1<<block))

            decode_residual_block(h,gb,intra_2dvlc,1,h->qp,d,h->l_stride);

    }

    /* chroma intra prediction */

    /* extend borders by one pixel */

    h->left_border_u[9] = h->left_border_u[8];

    h->left_border_v[9] = h->left_border_v[8];

    h->top_border_u[h->mbx*10+9] = h->top_border_u[h->mbx*10+8];

    h->top_border_v[h->mbx*10+9] = h->top_border_v[h->mbx*10+8];

    if(h->mbx && h->mby) {

        h->top_border_u[h->mbx*10] = h->left_border_u[0] = h->topleft_border_u;

        h->top_border_v[h->mbx*10] = h->left_border_v[0] = h->topleft_border_v;

    } else {

        h->left_border_u[0] = h->left_border_u[1];

        h->left_border_v[0] = h->left_border_v[1];

        h->top_border_u[h->mbx*10] = h->top_border_u[h->mbx*10+1];

        h->top_border_v[h->mbx*10] = h->top_border_v[h->mbx*10+1];

    }

    h->intra_pred_c[pred_mode_uv](h->cu, &h->top_border_u[h->mbx*10],

                                  h->left_border_u, h->c_stride);

    h->intra_pred_c[pred_mode_uv](h->cv, &h->top_border_v[h->mbx*10],

                                  h->left_border_v, h->c_stride);

    decode_residual_chroma(h);

    filter_mb(h,I_8X8);

    /* mark motion vectors as intra */

    h->mv[MV_FWD_X0] = intra_mv;

    set_mvs(&h->mv[MV_FWD_X0], BLK_16X16);

    h->mv[MV_BWD_X0] = intra_mv;

    set_mvs(&h->mv[MV_BWD_X0], BLK_16X16);

    if(h->pic_type != FF_B_TYPE)

        *h->col_type = I_8X8;

    return 0;

}

static void decode_mb_p(AVSContext *h, enum mb_t mb_type) {

    GetBitContext *gb = &h->s.gb;

    int ref[4];

    init_mb(h);

    switch(mb_type) {

    case P_SKIP:

        mv_pred(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_PSKIP, BLK_16X16, 0);

        break;

    case P_16X16:

        ref[0] = h->ref_flag ? 0 : get_bits1(gb);

        mv_pred(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_MEDIAN,   BLK_16X16,ref[0]);

        break;

    case P_16X8:

        ref[0] = h->ref_flag ? 0 : get_bits1(gb);

        ref[2] = h->ref_flag ? 0 : get_bits1(gb);

        mv_pred(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_TOP,      BLK_16X8, ref[0]);

        mv_pred(h, MV_FWD_X2, MV_FWD_A1, MV_PRED_LEFT,     BLK_16X8, ref[2]);

        break;

    case P_8X16:

        ref[0] = h->ref_flag ? 0 : get_bits1(gb);

        ref[1] = h->ref_flag ? 0 : get_bits1(gb);

        mv_pred(h, MV_FWD_X0, MV_FWD_B3, MV_PRED_LEFT,     BLK_8X16, ref[0]);

        mv_pred(h, MV_FWD_X1, MV_FWD_C2, MV_PRED_TOPRIGHT, BLK_8X16, ref[1]);

        break;

    case P_8X8:

        ref[0] = h->ref_flag ? 0 : get_bits1(gb);

        ref[1] = h->ref_flag ? 0 : get_bits1(gb);

        ref[2] = h->ref_flag ? 0 : get_bits1(gb);

        ref[3] = h->ref_flag ? 0 : get_bits1(gb);

        mv_pred(h, MV_FWD_X0, MV_FWD_B3, MV_PRED_MEDIAN,   BLK_8X8, ref[0]);

        mv_pred(h, MV_FWD_X1, MV_FWD_C2, MV_PRED_MEDIAN,   BLK_8X8, ref[1]);

        mv_pred(h, MV_FWD_X2, MV_FWD_X1, MV_PRED_MEDIAN,   BLK_8X8, ref[2]);

        mv_pred(h, MV_FWD_X3, MV_FWD_X0, MV_PRED_MEDIAN,   BLK_8X8, ref[3]);

    }

    inter_pred(h, mb_type);

    store_mvs(h);

    if(mb_type != P_SKIP)

        decode_residual_inter(h);

    filter_mb(h,mb_type);

    *h->col_type = mb_type;

}

static void decode_mb_b(AVSContext *h, enum mb_t mb_type) {

    int block;

    enum sub_mb_t sub_type[4];

    int flags;

    init_mb(h);

    /* reset all MVs */

    h->mv[MV_FWD_X0] = dir_mv;

    set_mvs(&h->mv[MV_FWD_X0], BLK_16X16);

    h->mv[MV_BWD_X0] = dir_mv;

    set_mvs(&h->mv[MV_BWD_X0], BLK_16X16);

    switch(mb_type) {

    case B_SKIP:

    case B_DIRECT:

        if(!(*h->col_type)) {

            /* intra MB at co-location, do in-plane prediction */

            mv_pred(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_BSKIP, BLK_16X16, 1);

            mv_pred(h, MV_BWD_X0, MV_BWD_C2, MV_PRED_BSKIP, BLK_16X16, 0);

        } else

            /* direct prediction from co-located P MB, block-wise */

            for(block=0;block<4;block++)

                mv_pred_direct(h,&h->mv[mv_scan[block]],

                            &h->col_mv[(h->mby*h->mb_width+h->mbx)*4 + block]);

        break;

    case B_FWD_16X16:

        mv_pred(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_MEDIAN, BLK_16X16, 1);

        break;

    case B_SYM_16X16:

        mv_pred(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_MEDIAN, BLK_16X16, 1);

        mv_pred_sym(h, &h->mv[MV_FWD_X0], BLK_16X16);

        break;

    case B_BWD_16X16:

        mv_pred(h, MV_BWD_X0, MV_BWD_C2, MV_PRED_MEDIAN, BLK_16X16, 0);

        break;

    case B_8X8:

        for(block=0;block<4;block++)

            sub_type[block] = get_bits(&h->s.gb,2);

        for(block=0;block<4;block++) {

            switch(sub_type[block]) {

            case B_SUB_DIRECT:

                if(!(*h->col_type)) {

                    /* intra MB at co-location, do in-plane prediction */

                    mv_pred(h, mv_scan[block], mv_scan[block]-3,

                            MV_PRED_BSKIP, BLK_8X8, 1);

                    mv_pred(h, mv_scan[block]+MV_BWD_OFFS,

                            mv_scan[block]-3+MV_BWD_OFFS,

                            MV_PRED_BSKIP, BLK_8X8, 0);

                } else

                    mv_pred_direct(h,&h->mv[mv_scan[block]],

                                   &h->col_mv[(h->mby*h->mb_width + h->mbx)*4 + block]);

                break;

            case B_SUB_FWD:

                mv_pred(h, mv_scan[block], mv_scan[block]-3,

                        MV_PRED_MEDIAN, BLK_8X8, 1);

                break;

            case B_SUB_SYM:

                mv_pred(h, mv_scan[block], mv_scan[block]-3,

                        MV_PRED_MEDIAN, BLK_8X8, 1);

                mv_pred_sym(h, &h->mv[mv_scan[block]], BLK_8X8);

                break;

            }

        }

        for(block=0;block<4;block++) {

            if(sub_type[block] == B_SUB_BWD)

                mv_pred(h, mv_scan[block]+MV_BWD_OFFS,

                        mv_scan[block]+MV_BWD_OFFS-3,

                        MV_PRED_MEDIAN, BLK_8X8, 0);

        }

        break;

    default:

        assert((mb_type > B_SYM_16X16) && (mb_type < B_8X8));

        flags = partition_flags[mb_type];

        if(mb_type & 1) { /* 16x8 macroblock types */

            if(flags & FWD0)

                mv_pred(h, MV_FWD_X0, MV_FWD_C2, MV_PRED_TOP,  BLK_16X8, 1);

            if(flags & SYM0)

                mv_pred_sym(h, &h->mv[MV_FWD_X0], BLK_16X8);

            if(flags & FWD1)

                mv_pred(h, MV_FWD_X2, MV_FWD_A1, MV_PRED_LEFT, BLK_16X8, 1);

            if(flags & SYM1)

                mv_pred_sym(h, &h->mv[MV_FWD_X2], BLK_16X8);

            if(flags & BWD0)

                mv_pred(h, MV_BWD_X0, MV_BWD_C2, MV_PRED_TOP,  BLK_16X8, 0);

            if(flags & BWD1)

                mv_pred(h, MV_BWD_X2, MV_BWD_A1, MV_PRED_LEFT, BLK_16X8, 0);

        } else {          /* 8x16 macroblock types */

            if(flags & FWD0)

                mv_pred(h, MV_FWD_X0, MV_FWD_B3, MV_PRED_LEFT, BLK_8X16, 1);

            if(flags & SYM0)

                mv_pred_sym(h, &h->mv[MV_FWD_X0], BLK_8X16);

            if(flags & FWD1)

                mv_pred(h, MV_FWD_X1, MV_FWD_C2, MV_PRED_TOPRIGHT,BLK_8X16, 1);

            if(flags & SYM1)

                mv_pred_sym(h, &h->mv[MV_FWD_X1], BLK_8X16);

            if(flags & BWD0)

                mv_pred(h, MV_BWD_X0, MV_BWD_B3, MV_PRED_LEFT, BLK_8X16, 0);

            if(flags & BWD1)

                mv_pred(h, MV_BWD_X1, MV_BWD_C2, MV_PRED_TOPRIGHT,BLK_8X16, 0);

        }

    }

    inter_pred(h, mb_type);

    if(mb_type != B_SKIP)

        decode_residual_inter(h);

    filter_mb(h,mb_type);

}

/*****************************************************************************

 *

 * slice level

 *

 ****************************************************************************/

static inline int decode_slice_header(AVSContext *h, GetBitContext *gb) {

    if(h->stc > 0xAF)

        av_log(h->s.avctx, AV_LOG_ERROR, "unexpected start code 0x%02x\n", h->stc);

    h->mby = h->stc;

    if((h->mby == 0) && (!h->qp_fixed)){

        h->qp_fixed = get_bits1(gb);

        h->qp = get_bits(gb,6);

    }

    /* inter frame or second slice can have weighting params */

    if((h->pic_type != FF_I_TYPE) || (!h->pic_structure && h->mby >= h->mb_width/2))

        if(get_bits1(gb)) { //slice_weighting_flag

            av_log(h->s.avctx, AV_LOG_ERROR,

                   "weighted prediction not yet supported\n");

        }

    return 0;

}

static inline void check_for_slice(AVSContext *h) {

    GetBitContext *gb = &h->s.gb;

    int align;

    align = (-get_bits_count(gb)) & 7;

    if((show_bits_long(gb,24+align) & 0xFFFFFF) == 0x000001) {

        get_bits_long(gb,24+align);

        h->stc = get_bits(gb,8);

        decode_slice_header(h,gb);

    }

}

/*****************************************************************************

 *

 * frame level

 *

 ****************************************************************************/

static void init_pic(AVSContext *h) {

    int i;

    /* clear some predictors */

    for(i=0;i<=20;i+=4)

        h->mv[i] = un_mv;

    h->mv[MV_BWD_X0] = dir_mv;

    set_mvs(&h->mv[MV_BWD_X0], BLK_16X16);

    h->mv[MV_FWD_X0] = dir_mv;

    set_mvs(&h->mv[MV_FWD_X0], BLK_16X16);

    h->pred_mode_Y[3] = h->pred_mode_Y[6] = NOT_AVAIL;

    h->cy = h->picture.data[0];

    h->cu = h->picture.data[1];

    h->cv = h->picture.data[2];

    h->l_stride = h->picture.linesize[0];

    h->c_stride = h->picture.linesize[1];

    h->luma_scan[2] = 8*h->l_stride;

    h->luma_scan[3] = 8*h->l_stride+8;

    h->mbx = h->mby = 0;

    h->flags = 0;

}

static int decode_pic(AVSContext *h) {

    MpegEncContext *s = &h->s;

    int skip_count;

    enum mb_t mb_type;

    if (!s->context_initialized) {

        s->avctx->idct_algo = FF_IDCT_CAVS;

        if (MPV_common_init(s) < 0)

            return -1;

        ff_init_scantable(s->dsp.idct_permutation,&h->scantable,ff_zigzag_direct);

    }

    get_bits(&s->gb,16);//bbv_dwlay

    if(h->stc == PIC_PB_START_CODE) {

        h->pic_type = get_bits(&s->gb,2) + FF_I_TYPE;

        if(h->pic_type > FF_B_TYPE) {

            av_log(s->avctx, AV_LOG_ERROR, "illegal picture type\n");

            return -1;

        }

        /* make sure we have the reference frames we need */

        if(!h->DPB[0].data[0] ||

          (!h->DPB[1].data[0] && h->pic_type == FF_B_TYPE))

            return -1;

    } else {

        h->pic_type = FF_I_TYPE;

        if(get_bits1(&s->gb))

            get_bits(&s->gb,16);//time_code

    }

    /* release last B frame */

    if(h->picture.data[0])

        s->avctx->release_buffer(s->avctx, (AVFrame *)&h->picture);

    s->avctx->get_buffer(s->avctx, (AVFrame *)&h->picture);

    init_pic(h);

    h->picture.poc = get_bits(&s->gb,8)*2;

    /* get temporal distances and MV scaling factors */

    if(h->pic_type != FF_B_TYPE) {

        h->dist[0] = (h->picture.poc - h->DPB[0].poc  + 512) % 512;

    } else {

        h->dist[0] = (h->DPB[0].poc  - h->picture.poc + 512) % 512;

    }

    h->dist[1] = (h->picture.poc - h->DPB[1].poc  + 512) % 512;

    h->scale_den[0] = h->dist[0] ? 512/h->dist[0] : 0;

    h->scale_den[1] = h->dist[1] ? 512/h->dist[1] : 0;

    if(h->pic_type == FF_B_TYPE) {

        h->sym_factor = h->dist[0]*h->scale_den[1];

    } else {

        h->direct_den[0] = h->dist[0] ? 16384/h->dist[0] : 0;

        h->direct_den[1] = h->dist[1] ? 16384/h->dist[1] : 0;

    }

    if(s->low_delay)

        get_ue_golomb(&s->gb); //bbv_check_times

    h->progressive             = get_bits1(&s->gb);

    if(h->progressive)

        h->pic_structure = 1;

    else if(!(h->pic_structure = get_bits1(&s->gb) && (h->stc == PIC_PB_START_CODE)) )

        get_bits1(&s->gb);     //advanced_pred_mode_disable

    skip_bits1(&s->gb);        //top_field_first

    skip_bits1(&s->gb);        //repeat_first_field

    h->qp_fixed                = get_bits1(&s->gb);

    h->qp                      = get_bits(&s->gb,6);

    if(h->pic_type == FF_I_TYPE) {

        if(!h->progressive && !h->pic_structure)

            skip_bits1(&s->gb);//what is this?

        skip_bits(&s->gb,4);   //reserved bits

    } else {

        if(!(h->pic_type == FF_B_TYPE && h->pic_structure == 1))

            h->ref_flag        = get_bits1(&s->gb);

        skip_bits(&s->gb,4);   //reserved bits

        h->skip_mode_flag      = get_bits1(&s->gb);

    }

    h->loop_filter_disable     = get_bits1(&s->gb);

    if(!h->loop_filter_disable && get_bits1(&s->gb)) {

        h->alpha_offset        = get_se_golomb(&s->gb);

        h->beta_offset         = get_se_golomb(&s->gb);

    } else {

        h->alpha_offset = h->beta_offset  = 0;

    }

    check_for_slice(h);

    if(h->pic_type == FF_I_TYPE) {

        do {

            decode_mb_i(h, 0);

        } while(next_mb(h));

    } else if(h->pic_type == FF_P_TYPE) {

        do {

            if(h->skip_mode_flag) {

                skip_count = get_ue_golomb(&s->gb);

                while(skip_count--) {

                    decode_mb_p(h,P_SKIP);

                    if(!next_mb(h))

                        goto done;

                }

                mb_type = get_ue_golomb(&s->gb) + P_16X16;

            } else

                mb_type = get_ue_golomb(&s->gb) + P_SKIP;

            if(mb_type > P_8X8) {

                decode_mb_i(h, mb_type - P_8X8 - 1);

            } else

                decode_mb_p(h,mb_type);

        } while(next_mb(h));

    } else { /* FF_B_TYPE */

        do {

            if(h->skip_mode_flag) {

                skip_count = get_ue_golomb(&s->gb);

                while(skip_count--) {

                    decode_mb_b(h,B_SKIP);

                    if(!next_mb(h))

                        goto done;

                }

                mb_type = get_ue_golomb(&s->gb) + B_DIRECT;

            } else

                mb_type = get_ue_golomb(&s->gb) + B_SKIP;

            if(mb_type > B_8X8) {

                decode_mb_i(h, mb_type - B_8X8 - 1);

            } else

                decode_mb_b(h,mb_type);

        } while(next_mb(h));

    }

 done:

    if(h->pic_type != FF_B_TYPE) {

        if(h->DPB[1].data[0])

            s->avctx->release_buffer(s->avctx, (AVFrame *)&h->DPB[1]);

        memcpy(&h->DPB[1], &h->DPB[0], sizeof(Picture));

        memcpy(&h->DPB[0], &h->picture, sizeof(Picture));

        memset(&h->picture,0,sizeof(Picture));

    }

    return 0;

}

/*****************************************************************************

 *

 * headers and interface

 *

 ****************************************************************************/

/**

 * some predictions require data from the top-neighbouring macroblock.

 * this data has to be stored for one complete row of macroblocks

 * and this storage space is allocated here

 */

static void init_top_lines(AVSContext *h) {

    /* alloc top line of predictors */

    h->top_qp       = av_malloc( h->mb_width);

    h->top_mv[0]    = av_malloc((h->mb_width*2+1)*sizeof(vector_t));

    h->top_mv[1]    = av_malloc((h->mb_width*2+1)*sizeof(vector_t));

    h->top_pred_Y   = av_malloc( h->mb_width*2*sizeof(*h->top_pred_Y));

    h->top_border_y = av_malloc((h->mb_width+1)*16);

    h->top_border_u = av_malloc((h->mb_width)*10);

    h->top_border_v = av_malloc((h->mb_width)*10);