Querying live media streams is a challenging problem that is becoming an essential requirement in a growing number of applications. Research in multimedia information systems has addressed and made good progress in dealing with archived data. Meanwhile, research in stream databases has received significant attention for querying alphanumeric symbolic streams. The lack of a unifying data model capable of representing multimedia data and providing reasonable abstractions for querying live multimedia streams poses the challenge of how to make the best use of data in video and other sensor networks for various applications including video surveillance, live conferencing and Eventweb. This paper presents a system that enables direct capture of media streams from sensors and automatically generates meaningful feature streams that can be queried by a data stream processor. The system provides an effective combination of extensible digital processing techniques and general data stream management research.

In the case of media and feature streams, explicit inter-stream constraints exist and can be exploited in the evaluation of continuous queries in the spirit of semantic query optimization. We express these properties using a media stream declaration language MSDL. In the demonstration, we present IMMERSI-MEET, an application built around an immersive environment. The IMMERSI-MEET system distinguishes between continuous streams, where values of different types come at a specified data rate, and discrete streams where sources push values intermittently. In MSDL, any dependence declaration must have at least one dependency specifying predicate in the body. As stream declarations are registered, the stream constraints are interpreted to construct a set of evaluation directives.