Network impairments are unpredictable and highly destructive to the perceptual quality of media content in the IPTV content distribution networks. As a result the existing network QoS based assessment methodologies are not adequate for the IPTV QoE assessment which determines the overall acceptability of a service as perceived by the end user. A discrete perceptual impact evaluation quality assessment framework (DEQA) is introduced in this paper. The proposed framework enables a real-time, non-intrusive assessment service by efficiently recognising and assessing the individual IPTV quality violation events in the distribution network. The discrete perceptual impacts to a media session are aggregated for the overall user level quality evaluation. With its deployment scheme, the DEQA framework also facilitates efficient network diagnosis and QoE management. Recent work on realising the functions of the framework is also presented.

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 begins by discussing video compression; it proposes and analyzes the use of filtering mechanisms as 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.

The integration of distributed multimedia systems around the unifying theme of quality of service (QOS) is addressed. A set of key QOS requirements is presented and mapped onto a provisional QOS architecture (QOS-A) that has emerged from a experimental system designed and implemented at Lancaster. The scope of the discussion is limited to aspects of a QOS-A for the support of continuous media communications. Also, the focus is on asynchronous transfer mode (ATM) at the network layer rather than the full range of multiservice networks. Functions and mechanisms for QOS support are examined and placed within the evolving QOS-A.>

The combination of high-speed multiservice networks and multimedia workstations offers considerable potential for the development of distributed multimedia applications. A key problem is how to integrate continuous-media types such as audio and video into a distributed workstation environment. An experimental system architecture based on a specialized multimedia network interface that attempts to provide this integration is described. The design and implementation of this system are discussed in depth in terms of workstation enhancement and distributed system support. A new approach to the problem of media synchronization is introduced, and the importance of quality of service in the architecture is highlighted. Experiences encountered during this work are described, comparison with other approaches is made, and likely future developments in multimedia network interfacing are discussed.>

The desire to transfer continuous media such as digital audio and video across packet switched networks imposes a number of new requirements on transport level communication services. This paper identifies a number of these requirements in the context of an experimental distributed multimedia infrastructure, and reports on research which addresses some of the associated issues. Particular attention is paid to two areas: (i) extended Quality of Service (QoS) provision; and (ii) support for the co-ordination of multiple related connections. We then describe an application level service, known as an orchestrator, which performs synchronisation functions over multiple related transport connections. We also outline the design and implementation of a continuous media transport service which meets the identified requirements. Finally, we outline the way in which the orchestrator and transport services are integrated into an object-based distributed multimedia application platform.