# Opusmodus

Opusmodus (OM) is a computer-aided composition (CAC) software designed for algorithmic and parametric music composition. It provides an integrated environment for composers, music theorists, and researchers seeking advanced tools for generative and parametric music processes. By enabling the systematic manipulation of multiple musical parameters (including pitch, rhythm, timbre, and articulation) through a Common Lisp–based scripting interface, Opusmodus offers high degrees of flexibility and control. Its extensible design allows users to explore diverse musical styles through rule-based procedures and algorithmic manipulations, thereby facilitating experimentation and innovation in both traditional and contemporary compositional contexts.
Opusmodus is intended for composers working across diverse musical contexts, including art music, concert music, choral repertoire, film scoring, jazz, electroacoustic (Electroacoustic music) composition, music for games, new media, and popular songwriting.

## History

Opusmodus was conceptualised by Janusz Podrazik in the early 2010s with the aim of streamlining and revolutionising complex compositional tasks within a single platform. The core development team included Bill St. Clair, Ernst van Waning, Gail Zacharias, Greg Pfeil, Janusz Podrazik, Martin Simmons, Matthew Emerson, Yehouda Harpaz, and Zachary Beane. Drawing on techniques from computational musicology and Common Lisp language, the initial release focused on delivering a functional environment for rule-based music generation. Over subsequent releases, the software expanded to include additional libraries, real-time interaction capabilities, and an enhanced user interface.

## Features

Opusmodus includes a suite of functions for data manipulation, pattern generation, and score construction, as well as a spectral analysis (Spectral music) tool that enables composers to extract and repurpose frequency content for advanced compositional processes. Its scripting interface (based on Common Lisp) supports user-defined processes, facilitating the creation of new compositional algorithms.
Opusmodus provides extensive microtonal capabilities by allowing composers to define pitch divisions well beyond the conventional twelve-tone equal temperament. This includes quarter-tone, eighth-tone, and arbitrary divisions of the octave, all integrated seamlessly into OMN (Opusmodus Notation) data. Scores using microtonality can be rendered in accurate notation or played back in real time, enabling detailed exploration of experimental pitch structures.
The software exports scores in industry-standard formats (e.g., MusicXML) and supports MIDI output, facilitating the transfer of musical ideas to traditional notation programs or virtual instruments. Opusmodus features its own notation system, called Opusmodus Notation (OMN), which represents musical elements like rhythm, pitch, dynamics, and articulations in a structured list format.
A robust library of musical functions index helps generate and transform pitches, rhythms, articulation patterns, and harmonic structures, supporting both tonal and atonal techniques.
Users can introduce stochastic processes into their compositions. These methods are customisable and allow for a wide range of musical outcomes, from deterministic sequences to heavily randomised structures.
Opusmodus GPT is a customised version of ChatGPT designed specifically for the Opusmodus community. It integrates the entire Opusmodus documentation and provides comprehensive usage examples. Opusmodus GPT is accessible via the standard (Free) ChatGPT interface, offering composers and developers an easily accessible resource for learning and experimenting with Opusmodus features. It provides precise guidance on functions, syntax, OMN scripting, and Common Lisp integration, ensuring accurate, documented support for composition, notation, and advanced techniques within Opusmodus.

## Use cases

Opusmodus has been adopted by composers, academic researchers, and music technologists. Its applications include:

### Academic research

Investigations into algorithmic composition, computational musicology, and artificial intelligence in the arts.

### Experimental composition

Creation of electroacoustic and instrumental works through advanced generative processes.

### Pedagogical purposes

Teaching algorithmic thinking in music conservatories and universities, where students learn to synthesise musical ideas through code.

## Universities using Opusmodus

* Mozarteum University Salzburg
* National University of Singapore
* University of Music and Performing Arts Vienna