Audio Time Compansion for Studio and Performance Synchronization

Recent research has provided systems that play musical accompaniment on real-time synthesizers while following the performance of human soloists. Another solution to electronic music's problem of syncing live players to pre-recorded tapes is a system using a time code synchronized tape deck whose audio output is pitch corrected for any tape speed deviation. A frequency shifter with SMPTE time code input is required for this task. With a computer-based, variable-rate time code generator, a musical performance can be compared against an internal representation of its score and external devices-be they audio or video tape machines, video disk players, or MIDI synthesizerssynchronized to the live action. Two forseeable uses of this interactive time code generator will be the freeing of musical sequencing tasks from the host computer in "synthetic performer"-allowing the computer to concentrate on pitch tracking and score following while sequencing and synthesis is accomplished by dedicated MIDI machines-and the synchronization of visual images-such as from video disk-to live musical performance. The complete system of time code generator and reader/pitch shifter will be outlined in this paper, and other uses for the technology developed therein will be suggested. Thesis Supervisor: Barry Vercoe Title: Professor of Music and Technology This work was supported by a grant from the System Development Foundation.