Mup produces very high quality PostScript printed music or a MIDI file from a text input file. It can handle almost any kind of music, instrumental or vocal, including tablature, shaped notes, guitar grids, alternate tunings, user-defined symbols, and much more. Mup has been under active development since 1992.
Paloma is a program to manage an SQL database of digital music files, and facilitate their retrieval and playback in interesting ways. It works with music files of any form -- MP3, Ogg Vorbis, MIDI... whatever you've got a player for. Paloma makes it easy to rip your entire CD collection and store it on your hard disk (or a collection of CD-Rs) for instant random access; playlists can then be generated using arbitrary SQL commands.
Sfront compiles MPEG 4 Structured Audio (MP4-SA) programs into efficient C programs that generate audio when executed. MP4-SA is a standard for normative algorithmic sound, which combines an audio signal processing language (SAOL) with score languages (MIDI and SASL). Under Mac OS X and Linux, sfront supports real-time, low-latency audio input/output and MIDI input. Under Mac OS X, sfront supports the creation of AudioUnit plug-ins. The documentation includes a book about SAOL programming.
iabc is a graphical application for editing music. It uses the ABC music notation language to produce high-quality graphical notation or MIDI output. The music notation and the ABC notation can be updated in real-time, making the construction of tunes using the ABC language hassle-free (or at least hassle-resistant).
Pymprovisator is a program for jazz musicians. Jazz music is based on improvisation and this program is intended to help musicians to improvise. The user sets the song parameters and the program generates a MIDI file with an adequate accompaniment. It emulates the program Band in a Box from PG Music. You can think of it as the electronic version of the books/CD from Jamey Aebersold.
FrAid (Fr[actal] Aid) is a programming language that is appropriate for mathematical computations, visualization, batch processing, and more. It features both a standalone application that provides a programming environment for the language and a system for integrating the language with Java. The Java interface allows mathematical equations and formulas to be used with Java code, making it easier to process numerical computations, symbolic computations, imaging, CAD, and more.
PyChoReLib is a Python library which transforms lists of notenames to a chordname. The system uses built-in music theory knowledge to make it easy and quick to add support for new chord types. Its features include interval recognition, scale recognition, and demo chord recognition using real-time input from MIDI devices.