Tools for Specifying and Executing Synchronized Multimedia Presentations

Multimedia applications require the handling of synchronization between media streams. We present tools for creating, editing and presenting synchronized multimedia objects. Specifying synchronization is supported by the graphical Synchronization Editor and execution of multimedia presentations is performed by the Synchronizer. Major topics cover requirements resulting from underlying distributed heterogeneous environments and the consideration of user interactions. The tools we have developed are not restricted to a fixed set of media, but support the inclusion of arbitrary user-defined media. The Synchronization Editor and the Synchronizer are part of the MODE project, that is used for the handhng of distributed multimedia objects in NESTOR, an authoring-learning environment in development at the Universities of Karlsruhe and Kaiserslautern in cooperation with the CEC Karlsruhe, Digital Equipment. 1 I n t r o d u c t i o n The integration of time dependent media in applications requires the synchronization of media streams. In this paper we describe object-oriented tools that support the graphical specification and execution of synchronized multimedia presentations. The developed components are the user-friendly graphical Synchronization Editor and the Synchronizer covering the requirements resulting from distribution of media objects in a heterogeneous environment. These requirements include the handling of error conditions as well as the support of alternative presentation forms and different presentation qualities for the heterogeneous platforms. Other important requirements met by the tools are the integration of any kind of user-defined media and the support of user interaction. The system is part of the MODE project (Multimedia Objects in a Distributed Environment) [Bla90, Bla91] that is used in NESTOR (Networked Systems for TutORing) [Muegl], an authorlng-learning environment that is in development at the