Performance Bottlenecks in Digital Movie Systems

Digital movie systems offer great perspectives for multimedia applications. But the large amounts of data involved and the demand for isochronous transmission and playback are also great challenges for the designers of a new generation of file systems, database systems, operating systems, window systems, video encoder/decoder and networks. Today's research prototypes of digital movie systems suffer from severe performance bottlenecks, resulting in small movie windows, low frame rates or bad image quality (or all of these!). We consider the performance problem to be the most important problem with digital movie systems, preventing their widespread use today. In this paper we address performance issues of digital movie systems from a practical perspective. We report on performance experience gained with the XMovie system and new algorithms and protocols to overcome some of these bottlenecks

Multimedia group communications: towards new services

Interpersonal communication among a group of users employing different media types is becoming more and more widespread in computing and telecommunications. Group communication places a variety of new requirements onto the underlying communications architecture and although many existing protocols and services do offer some limited support for multicast group communication, these new requirements make it difficult to find efficient and comprehensive solutions. The impact of multimedia group communication on the communication system and the way in which existing systems, international standardization bodies and researchers cope with these challenges is the subject of this paper. First the characteristics and requirements of multimedia group applications are discussed and illustrated by examples of existing group applications. Subsequently a survey of the kind of support available in today's communication system is presented. In addition the ongoing discussion about the standardization of group communication within ISO and ITU and the direction these efforts take is briefly summarized. Further, some selected examples of research projects which deal with different communication and protocol related aspects of multimedia group communication are presented which give an indication of the trends in this area