基于CDN的视频服务系统建模与仿真

QoS (Quality of Service) is a significant measure metric of evaluation of video service system. However, some factors existing in real world have a severe impact on QoS, particularly, loss of packets and packets delayed arrival which accounts for video frame jitter and surge of video start up delay in long distance transmission of video streaming data. By means of deployment of video servers in user communities, CDN (Content Delivery Network) can shorten the transmission path of video streaming, thus improve video QoS. This study established a comprehensive video service model based on CDN, where video-high-popularity-first algorithm was introduced to manage video cache replacement and real-time transcoding technology was used to compensate the pessimism caused by the deficiency of cache space. Experimental results showed that the video service system based on CDN behaved a packet loss rate of 3.1% and a packet delay rate of 4.7%, which meets the requirements of smooth video playback. And the average video start up delay is 2.841 seconds which can be accepted commonly. In short, metrics showed that the proposed architecture of video service performs prominent QoS.