# create binary string (00111001 etc.) - 5-byte length, then bbox
n = sprintf("%05b%0#{l}b%0#{l}b%0#{l}b%0#{l}b", l, a, b, c, d)
# pack into byte string
# create binary string (00111001 etc.) - 5-byte length, then bbox
n = sprintf("%05b%0#{l}b%0#{l}b%0#{l}b%0#{l}b", l, a, b, c, d)
# pack into byte string