+ // Check if the amount we will read minimally is available on input.
+ // The 64 represent the immediately next 2 frame_* elements read, the 23/4320
+ // represent a lower bound of the space needed for skipped superblocks. Non
+ // skipped SBs need more space.
+ if (get_bits_left(&gb) < 64 + s->num_superblocks * 23LL / 4320)