Research On Video Conference System Based On Application Layer Multicast

The video conference system is one of the widely used applications in the current Internet application market.Traditional video conference systems being built on the basis of hardware bring a huge amount of hardware costs,and limit the conference location.Besides,most video conference systems based on software adopt C/S architecture,which not only leads to high bandwidth costs but also may cause performance bottlenecks and and take the risk of unexpected crash of the server.In order to solve these problems above,a video conference system based on application layer multicast is designed and implemented.This paper adopts the topology of control signaling and media stream distribution based on the analysis of the current video conference systems' topology.The distribution for media streams uses the multi-source interactive application layer multicast scheme which is proposd based on the Chord algorithm.Considering the characteristics of video conference,the scheme removes the dummy nodes from the interactive multicast network,which reduce the number of forwarding times.And results of simulation of the scheme show that it has a good performance.In addition,practical functions are designed through analyzing requirements of video conferences.The detailed description of NAT traversal and the optimization method of symmetric NAT traversal are given.And a bandwidth controlling method based on an improved token bucket algorithm is designed to ensure the bandwidth for the video conference system.Further more,the occupancy of system resources for video conference systems is optimized,which promotes the scalability of the system.Finally,the prototype system is implemented based on WebRTC technology.This paper combines research and engineering practice.The video conference system based on the application layer multicast not only avoids the problems that may occur in the structure of C/S,but also has the advantages of low cost and wide using scope.And it is suitable for small and medium-sized video conference.The application layer multicast scheme has certain theoretical innovation and good application value.