Interactive Music and Synchronous Reactive Programming

Bertrand Petit¹ and Manuel Serrano²

The Art, Science, and Engineering of Programming, 2021, Vol. 5, Issue 1, Article 2

Submission date: 2019-09-27
Publication date: 2020-06-09
DOI:https://doi.org/10.22152/programming-journal.org/2021/5/2
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Abstract

This paper presents Skini, a programming methodology and an executionenvironment for interactive structured music. With this system, thecomposer programs his scores in the HipHop.js synchronous reactivelanguage. They are then executed, or played, in live concerts, ininteraction with the audience. The system aims at helping composers tofind a good balance between the determinism of the compositions and thenondeterminism of the interactions with the public. Each execution of aSkini score yields to a different but aesthetically consistentinterpretation.

This work raises many questions in the musical fields. How to combinecomposition and interaction? How to control the musical style when theaudience influences what is to play next? What are the possibleconnections with generative music? These are important questions for theSkini system but they are out of the scope of this paper that focusesexclusively on the computer science aspects of the system. From thatperspective, the main questions are how to program the scores and inwhich language? General purpose languages are inappropriate becausetheir elementary constructs (i.e., variables, functions, loops, etc.) donot match the constructions needed to express music and musicalconstraints. We show that synchronous programming languages are a muchbetter fit because they rely on temporal constructs that can be directlyused to represent musical scores and because their malleability enablescomposers to experiment easily with artistic variations of their initialscores.

The paper mostly focuses on scores programming. It exposes the process acomposer should follow from his very first musical intuitions up to thegeneration of a musical artifact. The paper presents some excerpts ofthe programming of a classical music composition that it then preciselyrelates to an actual recording. Examples of techno music and jazz arealso presented, with audio artifact, to demonstrate the versatility ofthe system. Finally, brief presentations of past live concerts arepresented as an evidence of viability of the system.