The Analysis And Implementation Of A Streaming Server Based On NGOD Architecture

With the development of digital multimedia and internet technology,as well as the gradually increased requirement on the multimedia program from Cable Television users,the traditional DVB(Digital Video Broadcast)business is not able to meet people's need any more.Interactive,customizable and various program give the direction in the future.Video on demand(VOD)satisfied this purpose nicely.This article explores several VOD architectures which is most popular currently in cable television area,and especially explores the architecture NGOD(Next Generation On Demand)raised by US Comcast corporation,on its background,technical attributes and prospect of the future.At present,most of NGOD compatible VOD components are still under research.Corresponding device manufacturers are speeding up the deployment of their devices capable of NGOD specific interfaces,but usable and NGOD compatible streaming server is still rarely seen in the market.This article will focus on the research of NGOD compatible streaming server,and gives a feasible implementation scheme.NGOD streaming server needs to process plenty of Real-time Streaming Protocol(RTSP)messages to manage video session,allocate required resource and help users control video playing.RTSP is a text-based protocol,and usually brings low process efficiency.In this article,through lots of analysis on the RTSP messages required by a NGOD streaming server,a multiple-key,zero-conflict hash algorithm will be raised to quickly parse RTSP messages,and the Time Complexity of this algorithm is expected to be O(1);VOD involves mass data and requires the latency as minimum as possible.To increase the response speed,this article gives lots of analysis and optimization on the server architecture,memory pool usage and thread pool management;When the message queue is used to convey user's data,the queue utilization is actually very random(sometimes the queue is spare,but other times it's very busy),this article raises an algorithm to dynamically manage message queue based on the characteristic of user's access.Compared to message queue allocated with a fixed length statically,this method could keep the response speed almost same as before,and improve the memory utilization greatly in the meantime.