Unique Id for DVDs and Apple DVP Player hash

[fortyfoxes]

I am creating a cross platform application for DVDs and I need to be abe to uniquely identify a DVD inserted into the drive. there seems to be no easily accessible ID in the DVD spec - is that right?

My preferred route would be to use the same technique as used by the Apple DVD player - it calculates some sort of hash and uses this to store metadata in a settings file. The filename of this settings file is based on this has and looks something like this example:

95b83c96e7415c34.plist

On OSX there are low level services that will calculate this ID - but I need to do this on other platforms - does anyone know how this hash is calculated - or if not what strategies should I try for working out my own unique ID?

[ChrissyBoy]

I would assume that the IFOs are unique per DVD. Therefore i would read the *.IFO files into memory and do a md5/crc on the bytes. The files are very small so it would be nearly instantaneous.