The Study Of QOS Key Technologies In Real-time Application Based On AVS And ISMA Framework

With the mobile digital TV, mobile TV, IPTV(Internet Protocol Television) new digital media business emergence rapidly, we have obtained an unprecedented audio-visual experience. At the same time, the rapid surge in business posed a severe test of the existing heterogeneous network. As the Internet only has the characteristics of best-effort, it does not able to transmit real-time data with any quality of service assurance. As a result, it has realistic and far-reaching significance to research how to improve the QoS(Quality of Service) indicators based on RTP/RTCP(Real-time Transport Protocol/Real-time Transport Control Protocol) under ISMA(Internet Streaming Media Alliance) framework.AVS(Audio Video coding Standard) is one of the second generation of source coding/decoding standards and own independent Chinese intellectual property rights. Researching streaming media transmission technology based on AVS standard can expand its application in commerce. It has very big significance for filling the blank of AVS standard's usage in this technology filed and promoting our audio and video industry development. This system's research and development are precisely based on up two purposes.This article begins with a brief analysis of the development status of QoS; Researching the AVS Audio Video Coding Standard and make a comparison and analysis of several of today's audio and video codec standard; A brief introduction to ISMA protocol framework which is needed by streaming media transmission. In particular, analysis and study RTP/RTCP characteristics and applications in-depth; Introduction of the current QoS parameters of major research strategies and indicators systematic, present myself key technical point: for packet loss, I propose packet-level FEC classification strategy based on packet fraction loss to recover lost packets; For the network delay, through dynamic adjustment of the transmitter encoder bit rate to achieve; These are the sender based on RTCP protocol through feedback quality information from the terminal transmission to adjust the QoS. At last, this paper designs and implements the corresponding transmission system and verifies the QoS indicators. Experimental results show that the system can guarantee video transmission quality at a large scale and achieve a certain degree of TCP-friendly in the case of poor network conditions.