static int decode_i_block(FourXContext *f, DCTELEM *block){
int code, i, j, level, val;
+ if(get_bits_left(&f->gb) < 2){
+ av_log(f->avctx, AV_LOG_ERROR, "%d bits left before decode_i_block()\n", get_bits_left(&f->gb));
+ return -1;
+ }
+
/* DC coef */
val = get_vlc2(&f->pre_gb, f->pre_vlc.table, ACDC_VLC_BITS, 3);
if (val>>4){