P2P流媒体分发模型及在视频会议系统中的应用

P2P-Based Media Streaming Distribution Model and Its Application in Video Conference System

针对传统视频会议系统服务质量较差的问题,提出了一种混合式流媒体分发模型VCStream(videoconference stream).模型中,由数据源节点构成一个树状系统,一旦树满,新加入的节点将进入一个备选池,从而备选池中的节点与树的所有叶子节点又构成了一个网状系统.基于该模型,设计了循环缓冲和两阶段调度算法,以优化流媒体数据的传输,达到提高可扩展性和容错性的目的.实验结果表明:与树状分发模型和随机拓扑结构模型相比,所提出的模型减少了10%～20%的传输延时以及新节点的加入时间;鲁棒性也比随机拓扑模型高5%,从而能更好地满足视频会议系统的需要.

In order to solve the problem of poor service quality of a traditional video conference system, a hybrid distribution model named VCStream （video conference stream） was proposed. In this model, a tree system is composed of source data nodes, and a reserve pool is used to store new nodes. As a result, in case the tree can not contain more nodes, another net system can be constructed by the nodes in the pool and all leaf nodes in the tree. Based on this model, a cyclic buffer and two-phase scheduling algorithm was designed to optimize transport for media streaming to enhance scalability and robustness. The experiment results show that compared with the tree topology and random topology models, the proposed model reduces 10% to 20% of transmitting delay and entering time of new nodes. Furthermore, the robustness of the proposed model is 5% higher than that of the random topology model, thus the proposed model meets the requirement of video conference systems.