Daniele Ghisi

Real-Time Computer-Aided Composition with bach

Environments for computer-aided composition (CAC), allowing generation and transformation of symbolic musical data, are usually counterposed to real-time environments or sequencers. The counterposition is deeply methodological: in traditional CAC environments interface changes have no effect until a certain ‘refresh’ operation is performed whereas real-time environments immediately react to user input. We shall show in this article that this distinction is by no means natural and that interactivity is an essential performative aspect of the musical discovery process. The reunification of the performative and speculative aspects is obtained via a Max library named bach: automatic composer’s helper, which is a set of tools for symbolic processing and graphical music representation, designed to take advantage of Maxs facilities for sound processing, real-time interaction and graphical programming.

Z-relation and homometry in musical distributions

This paper defines homometry in the rather general case of locally-compact topological groups, and proposes new cases of its musical use. For several decades, homometry has raised interest in computational musicology and especially set-theoretical methods, and in an independent way and with different vocabulary in crystallography and other scientific areas. The link between these two approaches was only made recently, suggesting new interesting musical applications and opening new theoretical problems. We present some old and new results on homometry, and give perspective on future research assisted by computational methods. We assume from the readers basic knowledge of groups, topological groups, group algebras, group actions, Lebesgue integration, convolution products, and Fourier transform.

Discrete phase retrieval in musical structures

This paper describes phase-retrieval approaches in music by focusing on the particular case of the cyclic groups (beltway problem). After presenting some old and new results on phase retrieval, we introduce the extended phase retrieval for a generalized musical Z-relation. This concept is accompanied by mathematical definitions and motivations from computer-aided composition. We assume from the reader basic knowledge of groups, topological groups, group algebras, group actions, Lebesgue integration, convolution products, and Fourier transform.

A max library for musical notation and computer-aided composition

This article introduces a library of external objects for real-time computer-aided composition and musical notation in Max. The library provides Max with a set of tools for the graphical representation of musical notation, manipulation of musical scores through a variety of approaches ranging from GUI interaction to constraint programming, and sequencing. The library is oriented to real-time interaction, and is meant to interoperate easily with other processes or devices controlled by Max, such as DSP tools, MIDI instruments, or generic hardware systems. These features and design choices place our software at the intersection of various categories of musical software environments and approaches, allowing it to help reduce the gap found between tools for sound-based, electroacoustic musical practices, and for symbol-based, traditional composition. The library is called “bach: automated composer’s helper.”

Representation of musical structures and processes in simplicial chord spaces

In this article, we present a set of musical transformations based on the representations of chord spaces derived from the Tonnetz. These chord spaces are formalized as simplicial complexes. A musical composition is represented in such a space by a trajectory. Spatial transformations are applied on these trajectories and induce a transformation of the original composition. These concepts are implemented in two applications, the software HexaChord and the Max object bach.tonnetz, dedicated to music analysis and composition, respectively.

Extending bach: A Family of Libraries for Real-time Computer-assisted Composition in Max

The bach library is a package for Max meant to bring symbolic music representation and computer-aided composition in a real-time environment (Agostini & Ghisi, 2013, 2015). In this article, we introduce a more ambitious project: situating the bach library inside a wider family of tools dealing with real-time computer-aided composition in Max, which we call the ‘bach family’. We give an overview of its core member (bach) and of its second member (cage: a high-level library of ready-made modules). We introduce its third member (dada: a library of non-standard user interfaces, currently under development), and discuss future perspectives and ideas.