Abstract:

Pattern definition is a fundamental component of music composition. This paper describes the implementation of item streams, an object-oriented representation of musical patterns that is capable of controlling any number of sound attributes simultaneously. As a rule, all patterns permit each element of pattern data or pattern control information to be a basic value or another pattern. Hybrid patterns are then created from a basic pattern set through recursive definition, by expressing a larger pattern in terms of one or more subpatterns. The scope of each subpattern is controlled by its period length, which sets the current limit of a subpattern's contribution to its superior pattern. The period length may also be used to force breadth first or depth first traversal, or it may vary dynamically according to its own pattern.