Offensive and defensive adaptation in distributed multimedia systems

. Adaptation ,in multimedia ,systems ,is usually ,restricted to defensive, reactive media adaptation (often called stream-level adaptation). We argue that offensive, proactive, system-level adaptation deserves,not less attention. If a distributed multimedia ,system ,cares for overall, end-to-end quality of service then it should provide a meaningful combination,of both. Weintroduce,an adaptive ,multimedia ,server (ADMS) and ,a supporting middleware which implement offensive adaptation based on a lean, flexible architecture. The measured ,costs and ,benefits of the ,offensive adaptation process are presented. Weintroduce an intelligent video proxy (QBIX), which implements defensive,adaptation. The ,cost/benefit measurements ,of QBIX are presented,elsewhere,[1]. Weshow,the benefits of the ,integration of QBIX in ADMS. Offensive adaptation is used to find an optimal, user-friendly configuration dynamically for ADMS, and defensive adaptation is added to take usage environment,(network and terminal) constraints into account.