/* decode B-frame mb_type bit ret_value 1 0 01 1 001 2 0001 3  */
static int32_t __inline get_mbtype(Bitstream *bs)
/* decode B-frame mb_type bit ret_value 1 0 01 1 001 2 0001 3  */
static int32_t __inline get_mbtype(Bitstream *bs)
{
  int32_t mb_type;
  for (mb_type = 0; mb_type <= 3; mb_type++)
    if (BitstreamGetBit(bs))
      return (mb_type);
  return -1;
}