Research On Streaming Media Content Distribution Network

Streaming by content distribution network (CDN) is an effective way to guarantee quality of service (QoS) of streaming media. Streaming media transmission and streaming media distribution are two functional modules of streaming media CDN, which improve QoS of streaming media from different aspects. Streaming media can adapt to the variety of network by certain streaming media transmission mechanisms, assuring QoS perceived by users as high and stable as possible. Streaming media can be distributed to edge network by distribution schemes so as to reduce network payload, avoid backbone network congestion, shorten users'startup latency, and steady the QoS of streaming media. The paper covers these two aspects, and main contributions are:1. To smooth the quality of continuous frames, highest bit plane based frame quality smoothing (HBPFS) scheme is proposed.2. Based on analysis and study of the characteristics of MPEG-4 FGS bit plane encoding, a GOP bit plane rate-distortion (R-D) model is deduced according to the FGS bit plane R-D model and the HBPFS scheme. A constant GOP quality bandwidth allocation scheme is presented. Offline and online algorithms are provided to make the quality of continuous GOP constant.3. An adaptive transmission system for MPEG-4 FGS streaming media is put forward based on the combination of two-phase quality smoothing scheme proposed and error control scheme. The system adjusts the sending bandwidth of every frame using GOP quality smoothing scheme, frame quality smoothing scheme and FEC error control scheme, in order to guarantee stable quality of continuous GOPs and successive frames in a GOP in the unstable and lossy Internet.4. With regard to the GOP quality smoothing scheme, three GOP quality smoothing strategies are brought forward, which are bandwidth based GOP quality smoothing (BWGS), enhancement layer based GOP quality smoothing (ELGS) and the highest bit plane based GOP quality smoothing (HBPGS) respectively.5. A prefix preferential layered caching strategy with prefetching algorithm is proposed for layered scalable coded streaming media. It can reduce users'startup lantency effectively with little effect on the byte hit ratio and network transmission cost of the whole system.