libtunepimp (library for media tagging using MusicBrainz servers) 

The TunePimp library is a MusicBrainz enabled tagging library that allows 
music files to be looked up. Once the files have been identified, libtunepimp 
writes new metadata tags to the music files and then writes the files to a 
standardized directory hierarchy. libmusicbrainz and libtunepimp are used by 
various media players to identify and tag media files.