aubio is a library for audio labelling. Its features include
segmenting a sound file before each of its attacks, performing
pitch detection, tapping the beat and producing midi streams from
live audio. The name aubio comes from 'audio' with a typo:
several transcription errors are likely to be found in the
results too.

aubio requires libsndfile and libsamplerate. It also will use 
jack-audio-connection-kit if available.