Some sort of filter based filesystem

[Svein Halvor Halvorsen]

What would be nice, is some kind of nullfs-like read only filesystem that 
would send all files through a configurable filter when opened. That way I 
could put all my music in FLAC format on hdd, and then, when I wanted to 
transfer some tracks to my portable player, I could grab the files from 
the ogg-directory. Or when I wanted to burn to CD-A, I could grab 'em from 
the wav-dir. 

Is something like this available somewhere? 
Or how about some other solution, not file system based?


Regards, 
Svein Halvor