prev_type = block_num_to_ptype_vlc_num[prev_type];
q = get_vlc2(gb, ptype_vlc[prev_type].table, PTYPE_VLC_BITS, 1);
if(q < PBTYPE_ESCAPE)
prev_type = block_num_to_ptype_vlc_num[prev_type];
q = get_vlc2(gb, ptype_vlc[prev_type].table, PTYPE_VLC_BITS, 1);
if(q < PBTYPE_ESCAPE)