$ perl -e'printf "0x%X\n", $_ for unpack "C4", "\x12\x34\x56\x78"'
0x12
0x34
0x56
0x78

##</code><code>##

$ perl -e'printf "0x%X\n", $_ for unpack "L<", "\x12\x34\x56\x78"'
0x78563412

##</code><code>##

unpack( 'a4 C C Q< L< L< L< C', $ogg_head )