PeerStreamer

        const int curr_mb_field_flag     = IS_INTERLACED(mb_type);

        if(s->mb_y&1){

            if (left_mb_field_flag != curr_mb_field_flag) {

                left_xy[1] = left_xy[0] = mb_xy - s->mb_stride - 1;

                if (curr_mb_field_flag) {

                    left_xy[1] += s->mb_stride;

                    topleft_partition = 0;

                    left_block = left_block_options[1];

                }

            }

        }else{

            if(curr_mb_field_flag){

                top_xy      += s->mb_stride & (((s->current_picture.mb_type[top_xy    ]>>7)&1)-1);

            }

            if (left_mb_field_flag != curr_mb_field_flag) {

                left_xy[1] = left_xy[0] = mb_xy - 1;

                if (curr_mb_field_flag) {

                    left_xy[1] += s->mb_stride;

                } else {

                    left_block = left_block_options[2];

                }

            }

        }

    }