The nature of distributed multimedia applications is such that they require multipeer communication support mechanisms. The multimedia traffic needs to be delivered to end-systems, networks and end-users in a form that they can handle while satisfying the constraints imposed by the multimedia application. Quality of Service (QoS) mechanisms that can ensure full quality media playout at high-performance workstations, while at the same time providing appropriately filtered lower quality media for playout at other end-systems, are required. Existing multicast support mechanisms are deficient for this purpose, in a heterogeneous environment, because they work on a common denominator premise where the quality delivered depends on the least capable link or node involved in the multicast session. This paper proposes and analyses the use of filtering mechanisms as a means of supporting disparate receiver capabilities and QoS requirements. The paper describes the implementation of a number of filtering mechanisms and highlights the communications architecture within which these mechanisms are built. This architecture constitutes a specific network topology and a new protocol family developed within a UNIX-like operating system.

No abstract

No abstract

There is now a huge variety of multimedia applications, network technologies and end-system architectures. Within this new and challenging environment, the importance of Quality of Service (QoS) mechanisms to allocate and monitor system resources has been recognised. A key goal of our research is how to manage the QoS requirements of heteregeneous receivers in applications that depend on multipeer communications. This paper presents results of our recent work on QoS filter mechanisms that operate on compressed video and audio streams. These filter mechanisms adapt the QoS of continuous media streams allowing diverse qualities of media to be delivered to a number of receivers in the same multipeer dissemination tree. The paper focuses particularly on filter operations applied to bandwidth-demanding video services in order to allow low capability clients, primarily connected via mobile and other lowbandwidth links, to participate in these dissemination services. This is performed without detriment to existing high capability clients. The results presented show the feasibility of providing individual QoS to individual clients.

The nature of distributed multimedia applications is such that they require multipeer communication support mechanisms. Multimedia traffic needs to be delivered to end-systems, networks and end-users in a form that they can handle while satisfying the constraints imposed by the multimedia application. Quality of Service (QoS) mechanisms are required that can ensure full quality media play out at high-performance workstations while at the same time providing appropriately filtered lower quality media for playout at low-end systems. Existing multicast support mechanisms are deficient for this purpose, in a heterogeneous environment, because they work on a lowest common denominator premise where the quality provided depends on the least capable link or node involved in the multicast session . In this paper we discuss a QoS model to provide receiver-dependent QoS based on filtering techniques, and we present initial experimental results.