On the quality and performance of active networking based media transcoding in multicast sessions

In this paper an advanced network service is described, which enables customisation of data services and adds extra flexibility to the network's data transporting capabilities. More specifically, a multicast service providing media transcoding inside the network is detailed. Whereas in traditional multicast services only one specific version of the data is available, in this service customers can choose from a range of different versions of the data. Customers can select a specific version according to their own wishes or to the capabilities of their connection and terminal. Based on active networking concepts, the different versions of the streamed data are created inside the network, by performing transformations of the original data in the network nodes. As a consequence, server load can be reduced and bandwidth usage in the multicast tree can be optimised. After the introduction of the multicast tree set-up strategies for this service, the focus of the discussion will be on performance aspects and on the resulting quality. In this discussion, a voice streaming service is considered, providing different encodings of the voice data.