3G视频传输中码率自适应调整算法  

Adaptive bitrate adjustment algorithm of video transmission based on 3G network

作　　者：林志勇[1,2] 叶桦[1,2] 孙晓洁[1,2] 仰燕兰[1,2] 

机构地区：[1]东南大学自动化学院,南京210096 [2]东南大学复杂工程系统测量与控制教育部重点实验室,南京210096

出　　处：《东南大学学报（自然科学版）》2012年第A01期45-50,共6页Journal of Southeast University：Natural Science Edition

基　　金：江苏省徐工集团院士工作站资助项目(BM2009562)

摘　　要：为了实现移动视频监控,介绍了一种基于中国联通3G网络的视频监控系统,并提出一种码率自适应调整算法.分析了3G网络视频传输中自适应调整码率的必要性,指出引起网络状况变化的两个主要因素.为了减小丢包率和获得平稳的视频流,提出了一种基于改进的AIMD算法来调整视频码率的流量控制算法.根据丢包率和视频延时把网络状况分为5个等级,对5个等级采取不同的码率调整策略:网络状况越差,码率减小越快,网络状况越好,码率增长越快.另外,为了保证视频质量,在减小码率的同时,减小帧率.实验结果表明,该算法可以正确地判断网络质量变化,把丢包率控制在很小的范围内,有效地改善了视频质量.在3G网络环境下,相比于现有的码率自适应调整算法,该算法在码率波动和丢包率方面都有一定的优势.In order to achieve mobile video monitoring, a type of network video surveillance system based on China Unicom＇s 3G network is introduced, and an adaptive bitrate adjustment algorithm is proposed. The necessity of adaptive rate adjustment in 3G video transmission is analysed and two major factors that cause the change of network condition are pointed out. In order to decrease packet loss rate and achieve a stable video stream, a flow control algorithm based on improved AIMD algo rithm is proposed. In this algorithm, network condition is divided into five grades based upon packet loss rate and video delay. The video bitrate is adjusted according to the grade of current network condition. The basic idea of the algorithm is that the worse the network condition, the faster the vid eo bitrate decreases; the better the network condition, the faster the video bitrate increases. Besides, in order to assure the quality of video stream, the frame rate is decreased while the video rate is de crease. Experimental results show that the algorithm can estimate the change of network condition correctly and limit the packet loss rate to a very small scale, thus the quality of video is improved ef fectively. Compared with the existing adaptive bitrate adjustment algorithms, the proposed algorithm can achieve better performances in bitrate fluctuation and packet loss rate in the 3G environment.

关 键 词：3G 丢包率 视频延时 码率调整 自适应调整 帧率 

分 类 号：TP393.4[自动化与计算机技术—计算机应用技术]