Without knowing much about CD-ROM file systems (except that Joliet is the M$ 'extended' standard, as far as I know -- and is different from the ISO one), if you say that cdrecord -V gives you what you want, why don't you do:

$cd_label = `cdrecord -V`;
[download]

Obviously, this isn't very portable, and I try to steer clear of system calls unless they are absolutely essential, but if it's just a simple script for your own use, you may as well.....