Time-setting of sound-objects

Bernard Bel

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.

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