Does anybody know how to identify (validate) mp3 files (other audio  
files would be interesting as well) by 'magic number'?
I never trust file extensions to be correct. It's to easy for users  
to accidentally munge file names in a GUI or even for malicious users  
to try bad things by simply changing file names.

Any library or code is welcome!
Daniel Berger said he'd even add it to Ptools or a similar library if  
it gets posted on Ruby-Talk.

I did find this online as a purported mp3 magic number (in hex of  
course),
49 44 33
but I'm not even going to bother using it since I don't know  
definitively that all mp3's will have it, and I don't know where to  
expect it in the file.

Thanks,
John Joyce