Improving IPTV services by H.264/SVC adaptation and traffic control

This paper presents a novel approach that combines both in-network, application-layer adaptation and network-layer traffic control of scalable video streams based on the H.264/SVC standard. In the IPTV/VoD scenario considered, an intercepting RTSP/RTP proxy performs admission control of the requested video, based on the signaled scalability information, and decides whether the content can be streamed without changes or in an adapted version. The proxy configures the network layer appropriately in order to separate the video stream from best-effort traffic on the same link. Rather than performing fixed bandwidth allocation, our proxy approach uses the hierarchical token bucket (HTB) queuing discipline to allow for borrowing bandwidth between traffic classes. In that setting, two different allocation policies are introduced. The hard reservation policy (HRP) performs admission control and adaptation on the video streams and does not modify video bandwidth allocation after admission. In contrast, the flexible borrowing policy (FBP) restricts the admission control to the base layer of the SVC stream. The packets carrying MGS enhancement layer data are marked with priorities by the proxy and are handled at the network layer by a priority-based queuing mechanism. Both a qualitative comparison and an experimental evaluation of the two policies are given.