unpack and ID3 tags

[Anon]

I'm trying to write an ID3 tag parser in php (i.e. a script that will look at an .mp3 file's ID3 tag and put the data into an object). I can't figure out how to use the unpack function. The manual says it works just like Perl, but I don't know Perl. Can anyone offer me some insight?

Thanks,

Justin