Representing Modifiable and Reusable Musical Content on the Web With Constrained Multi-Hierarchical Structures

The most commonly used formats for exchanging musical information today are limited in that they represent music as flat and rigid streams of events or as raw audio signals without any structural information about the content. Such files can only be listened to in a linear way and reused and manipulated in manners determined by a target application such as a Digital Audio Workstation. The publisher has no means to incorporate their intentions or understanding of the content. This article introduces an extension of the music formalism CHARM for the representation of modifiable and reusable musical content on the Web. It discusses how various kinds of multi-hierarchical graph structures together with logical constraints can be useful to model different musical situations. In particular, we focus on presenting solutions on how to interpret, navigate and schedule such structures in order for them to be played back. We evaluate the versatility of the representation in a number of practical examples created with a Web-based implementation based on Semantic Web technologies.