GENERIC QOS AWARE MEDIA STREAM TRANSCODING AND ADAPTATION

Abstract

In this paper we propose a generic and highly efficient QoS aware media adaptation and transcoding service. Based on a flexible component model, we have built adaptable network based media adaptation units that allow to change the codec and the quality of compressed media streams on demand during their transmission. Using a combination of sender rate adaptation, filtering and transcoding inside the transmission path, and receiver adaptation we can achieve an appropriate tradeoff between flexibility, bandwidth efficiency and security. Several media adaptation units together form an application layer overlay adaptation and transcoding network to support heterogeneous multimedia communication. We provide several measurements to evaluate the scalability of our approach both with respect to processing requirement and bandwidth scalability. We show that when using proper application level framing, quality adaptation can be achieved in real-time for several clients in parallel. 1.