static int decode_mb_info(IVI4DecContext *ctx, IVIBandDesc *band,

                          IVITile *tile, AVCodecContext *avctx)

{

    int         x, y, mv_x, mv_y, mv_delta, offs, mb_offset, blks_per_mb,

                mv_scale, mb_type_bits;

    IVIMbInfo   *mb, *ref_mb;

    int         row_offset = band->mb_size * band->pitch;



    mb     = tile->mbs;

    ref_mb = tile->ref_mbs;

    offs   = tile->ypos * band->pitch + tile->xpos;



    blks_per_mb  = band->mb_size   != band->blk_size  ? 4 : 1;

    mb_type_bits = ctx->frame_type == FRAMETYPE_BIDIR ? 2 : 1;



    /* scale factor for motion vectors */

    mv_scale = (ctx->planes[0].bands[0].mb_size >> 3) - (band->mb_size >> 3);

    mv_x = mv_y = 0;



    for (y = tile->ypos; y < tile->ypos + tile->height; y += band->mb_size) {

        mb_offset = offs;



        for (x = tile->xpos; x < tile->xpos + tile->width; x += band->mb_size) {

            mb->xpos     = x;

            mb->ypos     = y;

            mb->buf_offs = mb_offset;



            if (get_bits1(&ctx->gb)) {

                if (ctx->frame_type == FRAMETYPE_INTRA) {

                    av_log(avctx, AV_LOG_ERROR, "Empty macroblock in an INTRA picture!\n");

                    return AVERROR_INVALIDDATA;

                }

                mb->type = 1; /* empty macroblocks are always INTER */

                mb->cbp  = 0; /* all blocks are empty */



                mb->q_delta = 0;

                if (!band->plane && !band->band_num && ctx->in_q) {

                    mb->q_delta = get_vlc2(&ctx->gb, ctx->mb_vlc.tab->table,

                                           IVI_VLC_BITS, 1);

                    mb->q_delta = IVI_TOSIGNED(mb->q_delta);

                }



                mb->mv_x = mb->mv_y = 0; /* no motion vector coded */

                if (band->inherit_mv) {

                    /* motion vector inheritance */

                    if (mv_scale) {

                        mb->mv_x = ivi_scale_mv(ref_mb->mv_x, mv_scale);

                        mb->mv_y = ivi_scale_mv(ref_mb->mv_y, mv_scale);

                    } else {

                        mb->mv_x = ref_mb->mv_x;

                        mb->mv_y = ref_mb->mv_y;

                    }

                }

            } else {

                if (band->inherit_mv) {

                    mb->type = ref_mb->type; /* copy mb_type from corresponding reference mb */

                } else if (ctx->frame_type == FRAMETYPE_INTRA) {

                    mb->type = 0; /* mb_type is always INTRA for intra-frames */

                } else {

                    mb->type = get_bits(&ctx->gb, mb_type_bits);

                }



                mb->cbp = get_bits(&ctx->gb, blks_per_mb);



                mb->q_delta = 0;

                if (band->inherit_qdelta) {

                    if (ref_mb) mb->q_delta = ref_mb->q_delta;

                } else if (mb->cbp || (!band->plane && !band->band_num &&

                           ctx->in_q)) {

                    mb->q_delta = get_vlc2(&ctx->gb, ctx->mb_vlc.tab->table,

                                           IVI_VLC_BITS, 1);

                    mb->q_delta = IVI_TOSIGNED(mb->q_delta);

                }



                if (!mb->type) {

                    mb->mv_x = mb->mv_y = 0; /* there is no motion vector in intra-macroblocks */

                } else {

                    if (band->inherit_mv) {

                        /* motion vector inheritance */

                        if (mv_scale) {

                            mb->mv_x = ivi_scale_mv(ref_mb->mv_x, mv_scale);

                            mb->mv_y = ivi_scale_mv(ref_mb->mv_y, mv_scale);

                        } else {

                            mb->mv_x = ref_mb->mv_x;

                            mb->mv_y = ref_mb->mv_y;

                        }

                    } else {

                        /* decode motion vector deltas */

                        mv_delta = get_vlc2(&ctx->gb, ctx->mb_vlc.tab->table,

                                            IVI_VLC_BITS, 1);

                        mv_y += IVI_TOSIGNED(mv_delta);

                        mv_delta = get_vlc2(&ctx->gb, ctx->mb_vlc.tab->table,

                                            IVI_VLC_BITS, 1);

                        mv_x += IVI_TOSIGNED(mv_delta);

                        mb->mv_x = mv_x;

                        mb->mv_y = mv_y;

                    }

                }

            }



            mb++;

            if (ref_mb)

                ref_mb++;

            mb_offset += band->mb_size;

        }



        offs += row_offset;

    }



    align_get_bits(&ctx->gb);



    return 0;

}
