Logical Mapping: An Intermedia Synchronization Model for Multimedia Distributed Systems

Abstract

The preservation of temporal dependencies among different media data, such as text, still images, video and audio, and which have simultaneous distributed sources as origin, is an open research area and an important issue for emerging distributed multimedia systems, such as Teleimmersion, Telemedicine, and IPTV. Although there are several works oriented to satisfy temporal dependencies in distributed multimedia systems, they are far from resolving the problem. In this paper we propose a logical synchroniza- tion model able to specify at runtime any kind of temporal relationship among the distributed multimedia data involved in a temporal scenario. The synchronization model is based on a new concept that we call logical mapping. A logical mapping, in general terms, translates a temporal relation based on a timeline to be expressed according to its causal dependencies. The logical mappings allow us to avoid the use of global references, such as a wall clock and shared memory. We note that the proposed intermedia synchronization model does not require previous knowledge of when, nor of how long, the media involved of a temporal scenario is executed. Finally, in order to show the viability of the proposed model, a syncrhonization approach is presented.