Hybrid media streaming architecture, focussing on quantification of scalability of media streaming architectures, including streaming protocal evaluation.
An analysis of media streaming architectures is performed in this dissertation drawing focus to the advantages and disadvantages of the various architectures. Detailed examination is given to scalability of decentralized Peer-to-Peer (P2P) systems in comparison to centralized client-server systems in an aim to quantify the difference in scalability between the architectures. Research has indicated that decentralized architectures are found to have better scalability. Taking into consideration the various factors and protocols encountered in many researched multimedia streaming architectures, a decentralized P2P Video on Demand (VoD) media streaming system using Set-Top Boxes (STBs) is proposed. Both centralized and decentralized architectures are simulated in Network Simulator 2 (NS2), with the inclusion of an enhanced Evalvid (Video Evaluation) toolset which allows utilization of Peak Signal to Noise Ratio (PSNR) to determine received video quality. An evaluation methodology, referred to as the Quality and Scalability Quantification System (QSQS), is developed and successfully tested using PSNR to determine differences in quality and scalability between the architectures. Results indicate that the decentralized architecture has on average 15 % higher delivered video quality and 34 % higher scalability than the centralized architecture under similar operating conditions. Under very high network loads, drawbacks to decentralized architectures are observed and examined, with a centralized nature emerging amongst peer nodes causing a resultant loss in network robustness. In response to this, a protocol that introduces serving peers is implemented in the decentralized architecture. Evaluation of the serving peer protocol found an increase of almost 30 % in delivered video quality to all peers when compared to the standard architecture. Performance of the evaluation methodology in evaluating the serving peer protocol enhances possibilities of using this method as a Quality of Experience (QoE) indicator in addition to existing Quality of Service (QoS) evaluation methods.
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