Multimedia presentation technology has enormous potential for a myriad of applications including academic classrooms, industrial training, and business presentations. As presentation technology advances, it is possible to incorporate a wider range of media including variable duration media such as simulations and animations. At the same time, users are able to take more control over presentations by controlling the rate and selection of media being played. To make full use of these advances, multimedia systems must support flexible presentations that incorporate many variations in the way they are played. This paper identifies three requirements for flexible presentations and derives four requirements for synchronization of flexible presentations. The paper presents flexible interactive presentation synchronization (FLIPS), a model for specifying coarse synchronization for flexible presentations. FLIPS supports a wide range of temporal synchronization specifications. It also provides algorithms for attaining a consistent and coherent presentation state in response to user interaction (e.g. skipping to a different slide or selection) and other state-changing events. Applications of the FLIPS model are discussed.

SuiteSound, a programming environment with integrated support for multimedia, is discussed. SuiteSound is built in the Suite object-based system on a conventional UNIX operating system. SuiteSound objects incorporate multimedia by creating flows and filters. Flows are streams of multimedia data moving through a sequence of objects. They bridge the gap between objects representing the state of an entity at a discrete point in time and space and continuous media such as live audio or video. Filters are intermediate objects between the source and destination of a flow. They take flow as input, perform one of several operations such as multiplex-in, multiplex-out, gain control, or silence deletion on it, and send the resulting flow to its destination. In effect, they provide a virtual device interface for the application programmer that is uniform and independent of any physical device. The design and implementation of SuiteSound on the Sun SparcStation are described. Experiments performed to determine the network and CPU load of the sound tool are reviewed.>