libmusicbrainz (library for accessing MusicBrainz servers) 
MusicBrainz is a user-maintained community music metadatabase. 
The MusicBrainz client library allows applications to make metadata 
lookups to a MusicBrainz server, generate signatures from WAV files 
and create CD Index Disk IDs from audio CD-ROMs.

This requires libdiscid.
