Here are CBMR/MIR algorithm implementations I was working on in 2002-2003 as a part of a musical information retrieval project C-BRAHMS. These are the only existing implementations of some of the algorithms. For more information, refer to:
The following repository contains pure Ruby implementations of geometric algorithms. The second version of P3 fixes a bug in the published algorithm.
The following repository contains a complete high-performance MIR/CBMR search engine for searching melodies from MIDI files. Algorithms are implemented in C.