摘要
码率平滑通过降低发送码流的突发性成为提高网络带宽利用率的一种有效手段.为提高平滑性能和降低资源需求,利用原始码流在平均码率线上的波动形式,提出了一种对视频数据进行自适应分段的码率平滑算法t-PCRTT.该算法在相同分段数下能够有效降低客户端缓冲区需求,分析函数上的平滑结果显示它的缓冲区需求不足PCRTT算法的50%.在采用MPEG4和H.264两类编码影片的性能评估实验中,t-PCRTT的最小缓冲区需求明显降低,在不同缓冲区下的码率变化次数接近于最优值,能够更好地支持VCR-Window模式下的VCR操作.
Bandwidth smoothing can effectively improve network bandwidth utilization by reducing the burstiness of VBR traffics.The main idea is to transmit the video data of big frames to client buffer prior to their due time.PCRTT can result in a suboptimal transmission schedule with lower computational complexity.However,it is difficult to obtain good-performance parameters,including segmentation and rate computation.In this paper,we first analyze the key difference between the classic smoothing algorithms that can all achieve some optimal metrics.Then we propose an adaptive segmentation algorithm of PCRTT called t-PCRTT according to the fluctuation trend of the playback traffic around the average rate line.As a result,the algorithm can significantly decrease the required client buffer size with the equal number of segments due to its tightly tracking the playback data curve.Using the analysis function,we verify that the required buffer size of t-PCRTT is less than half of PCRTT.The final simulation results using the MPEG4 and H.264 video traces show that t-PCRTT outperforms PCRTT with the same number of segments,and that t-PCRTT almost achieves the optimal number of rate changes and well supports the VCR operation based on VCR-window under various buffer sizes.
出处
《计算机研究与发展》
EI
CSCD
北大核心
2010年第10期1700-1708,共9页
Journal of Computer Research and Development
基金
国家"八六三"高技术研究发展计划基金项目(2008AA01A317)~~
关键词
视频点播
变码率比特流
码率平滑
视频传输与发送
服务质量
恒码率
video on demand
variable bit rate
bandwidth smoothing
video transmission and transport
quality of service
constant bit rate
