Abstract. Distributed multimedia applications are very sensitive to resource variations. An attractive way for dealing with dynamic resource variations consists in making applications adaptive, and even self-adaptive. The objective is to grant applications the ability to observe themselves and their environment, to detect significant changes and to adjust their behavior accordingly. This issue has been the subject of several works; however the proposed solutions lack flexibility and a high-level support that eases the development of adaptive applications. This paper presents PLASMA, a component-based framework for building multimedia applications. PLASMA relies on a hierarchical composition and reconfiguration model which provides the expected support. The experimental evaluation shows that adaptation can be achieved with a very low overhead, while significantly improving QoS of multimedia applications as well as resource usage on mobile equipments.

With the proliferation of networked devices, today's multimedia applications operate, as never before, in heterogeneous and dynamic environments. An attractive way to deal with this situation is to make applications self-adaptive (or self-reconfigurable); that is, make them able to observe them-selves and their environment, to detect significant changes and to reconfigure their own behavior in QoS-specific ways. This issue has made the subject of numerous works, especially in the context of multimedia applications. However, several key requirements of adaptivity have not been well addressed such as: the generality to a wide range of applications, the customizability to each application context and the flexibility of reconfiguration mechanisms. We address these aspects in a component-based framework for building self-reconfigurable multimedia applications, named PLASMA. This paper describes the architecture of PLASMA and shows its use through an application use case. Experimental evaluations show that reconfigurations have a low cost, while significantly improving the QoS.

With the increasing number of networked devices, multimedia applications require additional functionality inside the network in order to adapt multimedia streams. In this field, much research work has been proposed; however, the dynamic configuration and the reconfiguration at run-time of such services remain little studied. This paper addresses these issues and describes a framework for the dynamic configuration and the reconfiguration of network-based media adaptation. We show through experimental evaluations that besides adaptations, reconfiguration can improve significantly the performance of client applications with a minimal cost.

Abstract. Streaming multimedia applications, such as video on demand or conferencing are increasingly deployed in heterogeneous and mobile environments including Workstations, PDAs, mobile phones, etc. These applications are very resource demanding and in general, they need to be dynamically adapted when executed on low capability terminals. The proxybased content adaptation approach is well suited to transparently adapt in real time multimedia data on intermediate nodes without modifying the application. In this paper, we report on experiments on dynamic configuration of such proxies by using a configuration language called APSL (Adaptation Proxy Specification Language). We developed a configurable proxy allowing adaptation of existing videoconferencing applications, and evaluated the performance benefits of the proxy approach using a DirectShow/COM-based framework.