分布式协作系统的多方视频传输方法

针对分布式多方视频协作系统中采用视频服务器中继多路视频数据的集中式方法存在可扩展性低、重负载下实时性难以保证以及单点失效等问题，提出一种分布式多方视频数据传输方法。通过测量协作组节点延时，每个协作组建立一个基于Mesh拓扑结构的低延时覆盖网络，并采用拓扑维护机制来保证视频数据的传输。组中多路视频流通过纯分布式方法进行传输，协作节点以“拉”的方式从邻居节点得到多路视频流数据。在存在节点带宽抖动和节点扰动的情况下，通过自适应视频编码率控制机制以保证每个协作节点均能及时得到组中多路协作视频流数据。试验仿真结果表明，分布式多方视频传输方法相对集中式的方法具有更好的可扩展性、实时性和鲁棒性。

Multi-party video transmission method in distributed cooperative system

The distributed multi-party video cooperative system usually suffers problems of the low scalability, low real-time performance under heavy payload and single point failure, if all video streams are relayed by a video server in centralized way. A distributed multi-party video transmission scheme was proposed. A mesh overlay network with low delay was constructed by measuring the delay between cooperative peers for every cooperative group. The topology maintenance mechanism was designed to ensure transmission of video streams. Video streams in a cooperative group were transmitted in pure distributed way where cooperative peers receive multi-streams from their neighbor peers in terms of the "pulling" method. Furthermore, under the condition of bandwidth changing and peers churning, an adaptive control mechanism of encoding rate was used to ensure that every cooperative peer can receive multi-streams in time. The simulation results indicate that the method of distributed multi-party video transmission has higher scalability, better real-time performance and stronger robustness than that in the centralized way.