[ Thanks to slothy
for this link. ]
We have released the Songprint library for our eTantrum Music ID
Songprint is a GPL’d library that can identify any piece of
music based on its unique audio fingerprint. The fingerprint is
independent of the codec and bitrate of the compressed file. The
package includes a reference implementation which can identify MP3,
OggVorbis, and WAV files.
You can download the code on SourceForge.