Time-setting of sound-objects: a constraint-satisfaction approach. Invited paper, Workshop on Sonic Representations and Transforms. INTERNATIONAL SCHOOL FOR ADVANCED STUDIES (ISAS), Trieste, 26-30 October 1992.
This paper deals with the scheduling of “sound-objects”, hereby meaning predefined sequences of elementary tasks in a sound processor, with each task mapped to a time-point. Given a structure of sound-objects completely ordered in a phase diagram, an “instance” of the structure may be obtained by computing the dates at which each task should be executed. Time-setting the structure amounts to solving a system of constraints depending on (1) metric and topological properties of sound-objects, (2) contexts in which they are found, and (3) parameters related to the performance itself (“smooth” or “striated” time, speed, etc.). This may require relocating/truncating objects or delaying part of the sound-object structure. A constraint-satisfaction algorithm is introduced, the time complexity of which is O(n.k) in most cases, where n is the number of sequences and k the maximum length of a sequence. In the worst case it remains better than O(n2.k3). Other fields of applications are proposed, including multimedia performance and computer-aided video editing.