Multimedia Systems

1. Multimedia Systems Instructor: Bajuna Salehe Email: bajunar@yahoo.com Web: http://www.ifm.ac.tz/staff/bajuna/courses Distributed Multimedia Systems

2. What is Distributed Multimedia Systems (DMMS)? • Distributed multimedia systems consist of multimedia databases, proxy and information servers, and clients, and are intended to for the distribution of multimedia content over the networks.

3. DMMS • A simple architecture of DMMS

4. Multimedia Requirements • The advent of multimedia has largely divert the computing process in the distributed system • This necessitated to have new requirements on such system:

5. Multimedia Requirements • Providing support for continuous media types, such as audio, video and animation. • The introduction of such continuous media data to distributed systems demands the need for continuous data transfers over relatively long periods of time. • High bandwidth is required.

6. Multimedia Requirements • The second requirement of distributed multimedia applications is the need for sophisticated quality of service (QoS) management. • Ensuring that the service requests should be met. • Supporting multiparty communications. • Many distributed multimedia applications are concerned with interactions between dispersed groups of users. • E.g. remote conference application.

7. DMMS and Client Tools • A decade ago, networked multimedia systems were capable of supporting mostly devices like Personal computers and/or a small LAN set-up. • Then the coming of modern wireless technology change the way multimedia rendering. • Increase the volume of traffic due to transfer of simple media clips, images, text massages to long duration data.

8. DMMS and Client Tools • The modern day DMMS extends to entertainment in the form of games and casinos on networks. • The resources needed for DMMS would include: • Adequate number of copies of movies at the multimedia databases (MMDs), • Adequate bandwidth of the network to support media streams

9. Key Technologies and Solutions in the Design of a DMMS • Key challenges in attaining good design is on managing resources. • For instance owing to high-bandwidth availability, several applications become plausible for users that will enforce a continuous work pressure on the media servers on the network. • Key issues for designing good DMMS solutions:

10. Major Service Categories: Video-On-Demand (VoD) versus Video-On-Reservation(VoR): • VoD is certainly an attractive technology in rendering digital video libraries, distance learning, electronic commerce, etc, as • Users can request the service any time and from anywhere and, • Service allows users to have a complete control of the presentation.

11. Video-On-Reservation(VoR) • Contrary to VoD, when users reserve for a movie presentation in advance, VoD manifests in the form of VoR. • Under VoR service, system is shown to utilize resources in an optimal manner as user viewing times are known in advance. • Perhaps VoR is better suited for pay-per-view by SPs for digital TV subscribers.

12. Caching in DMMS • Caching is one of the inevitable and powerful solution approaches that influence almost every performance metric under consideration. • Caching allows nodes to quickly fetch the required documents without incurring the need to contact the original host.