Distribution of digitally encoded presentations

Abstract

Digitally encoded presentations are provided at the request and convenience of receivers associated with a data distribution system. The problem of reliably satisfying large numbers of randomly occurring receiver demands for digitally encoded presentations, particularly from a single storage copy of the presentation, and particularly for linear presentations, is addressed. The invention may be embodied in a system which includes a repository of digitally encoded presentations, cache memory for holding presentations which are being supplied to receivers, and a multicasting network for connecting the system to receivers. By grouping receivers into receiving groups for receiving multicasts of presentation segments, the system can satisfy the requests of any number of individual receivers, irrespective of other receivers receiving the presentation. For linear presentation, presentation segments may be defined to be of equal duration, and receiving groups may automatically be provided with sequential segments of the presentation. The system will optimally be capable of multicasting all segments of a linear presentation within a period equalling the predefined segment duration.