Research On Distribution Technology Of Multimedia Clouding Application

With the development of multimedia clouding applications and broadband technology, Multimedia group communication applications, such as multi-point video conference, major news and events live, Internet-on-demand TV, network video monitoring and so on, continue to emerge. Content Distribution technology has been widely used in the group communication applications. In recent years, application layer-based overlay network multicast service technology has been more and more attention. Without underlying equipment upgrades and extension, multicast services can be configured as needed. However, due to capacity limitations of end system, the current overlay network multicast routing technology for large-scale multimedia group communication applications, still faces three major challenges:1) Insufficient capacity of end system leads to a longer overall distribution delay of problems;2) Dynamics of end system leads to a longer overall distribution delay of problems;3) Local disaster leads to quality decline in the distribution.The dissertation’s work is under support of National Scientific Important Project,"Research On Key Techonologies of Future Mobile Multimedia Video/Audio Codec"(No.2010ZX03004-003) and Wuhan Scientific Supply&Demand Plan Project "Internet-based Picture Trading System".The major contributions of this dissertation are as follows:(1)Degree-Constrained Optimized Minimum delay spanning tree algorithm. Overlay Multicast spanning tree algorithms have larger latency issues under the condition of degree-constrained. The existing node selection model calculates only the length of delay as a judgment basis for the order of node joining tree, without considering the node’s relay capacity constraints. In this case, a node with shorter delay but poor degree may be chosen firstly, resulting in larger overall delay. This dissertation studies degree-constraints’influences on the multicast delay, and claims Degree-Constrained Optimized Minimum delay spanning tree algorithm(DCMD-D). Compared with the DCMD-H algorithm, DCMD-D algorithm is more accurate in the calculation of judgment metric weights. Experiments show that the proposed algorithm could achieve2%-6%lower latency. The result applied to real-time group-multimedia system construction can reduce user waiting time.(2) A fast QoS re-routing algorithm of overlay network.Traditional QoS re-routing algorithms used the back-up method of reconstruction and restoration of interrupted service to switch the path, but did not consider the routing delay of the reconstruction costs of the process, which will cause delay in recovery time and low efficiency of service problems. To solve this problem, this paper puts forward a fast QoS re-routing algorithm. The method is the introduction of reconstruction delay of the path to restrict at alternative path selection. It is in favor of election of the resumption of faster alternative path. Expand of a Failure regional approach will be to elect the course of a single alternative path into the path of a collection of selected options. It will improve success probability of re-routing. Simulation results show that the algorithm can effectively improve the routing efficiency of recovery time, compared with the traditional algorithm to reduce the average5%-8%of the restoration of the delay time, increase5%increase success rate of repair..(3) multi-service overlay system model for multimedia clouding distribution. At present, most traditional distribution systems adopt special distribution services framework, often only for the characteristics of multimedia applications with a single provision, and cannot provide service guarantee for group-multimedia communication. To solve this problem, this dissertation designed to work on a tiered service multimedia group-communication system architecture. Compared with traditional single system, the system can simultaneously achieve pictures, video and real-time streaming and other types of distribution services. It leaves out repeat system development and saves the system maintenance overhead. Meanwhile, incorporating this overlay multicast theoretical results, this dissertation designs distinct service-quality assurance mechanism for group multimedia services to improve performance and stability.In summary, this dissertation results from the application-layer overlay network to explore the perspective of the quality(QoS) of efficient and reliable multicast distribution control strategy for large-scale multimedia clouding system design, and provide innovative science guiding ideology. It is of an important theoretical significance for research and development of automotive multimedia communication systems, IPTV useful products. Finally, this dissertation shows the prospects for future research.