The following code illustrates how to descend into a chunk of a file.

   HMMIO hmmio1;
   MMCKINFO mmckinfo;
   USHORT usFlags = 0;
   USHORT rc;
    ...

   memset( &mmckinfo, '\0', sizeof(MMCKINFO) );
   usFlags |= MMIO_FINDRIFF;
   mmckinfo.ckid = FOURCC_WAVE;

   rc = mmioDescend(hmmio1, &mmckinfo, usFlags);
   if (rc)
     /* error */
   else
    ...