Implement And Coding Rate Adjustment Research Of Network Video Monitoring System

Along with the rapid development of computer technology, video monitoring system is getting more and more widely used in domestic, enterprise, government and many other fields for social security guarantee demanding.It has wide space and promising market. Through the network transmission, users can browse the video images miles away, but feel they were actually there.Video monitoring system after experienced simulation system, digital system, and network system, now is stepping into high definition, and intelligent era. Video monitoring system (VMS) is a large and high-tech project, while how to build scalable VMS is a challenging problem. VMS is an application form of real-time streaming media transmission, how to ensure the quality of streaming media service on packet loss, real-time, is still a serious problem.The main contents of this paper are organized as follows:(1) This paper presents a structure of VMS, which is divided into four levels:1.Place the all kinds of encoder on equipment coding layer.2. Place the specific forwarding service, video service on media service layer.3. Place the access service, center, network management services on business management layer.4. Place the client-side and the management-end software on user management layer. At the same time based on the distributed system, make service module independence in software, easy to manage and maintain. Based on the structure of stratification and distribution, this paper make video transmission of real-time communication into three steps and made a detailed demonstration for each step:firstly register business management. Secondly asking the media service layer’s route information. Thridly, request for monitor the data. And then design their data structure based on the communication process analysis front-end encoder modules and forwarding the server access needs analysis, to realize the front-end encoder access module and streaming media delivery server module.(2) According to the technical characteristic of Real-time streaming media adaptive transmission control method, there are three ways of transmission:based on network equipment, based on available bandwidth estimate, based on the terminal. Based on the method of network need to modify the existing network transmission device, and difficult to deploy. Based on the method of available bandwidth estimate will introduce additional network load, or modify the standard network communication protocols. While, based on the terminal has its advantages in implementing and not rely on environment.This paper introduces the QASM model, designs the send-buffer on the application layer, according to the data of buffer to adjust the coding rate, which has three adjustment state:decline state, stable state,and increasing state. We explain the converting conditions and coding rate adjustment strategy.(3) Finally, QASM proved to be a great performance by testing in adaptive speed, packet loss rate under the network video monitoring systems.