计算机应用 ›› 2019, Vol. 39 ›› Issue (4): 1127-1132.DOI: 10.11772/j.issn.1001-9081.2018091893

• 网络与通信 • 上一篇    下一篇

动态自适应的HTTP流码率渐进切换算法

涂大喜, 蒋宇浩, 徐成, 余林琛   

  1. 中国地质大学 计算机学院, 武汉 430074
  • 收稿日期:2018-09-10 修回日期:2018-10-26 出版日期:2019-04-10 发布日期:2019-04-10
  • 通讯作者: 余林琛
  • 作者简介:涂大喜(1996-),男,湖北黄冈人,硕士研究生,主要研究方向:流媒体、视频云转码;蒋宇浩(1993-),男,湖北随州人,硕士研究生,主要研究方向:流媒体、可伸缩视频编解码;徐成(1995-),男,江西上饶人,硕士研究生,主要研究方向:网络视频传输;余林琛(1977-),女,四川南充人,副教授,博士,主要研究方向:云计算、移动视频。
  • 基金资助:
    国家自然科学基金资助项目(61502439)。

Dynamic adaptive step-wise bitrate switching algorithm for HTTP streaming

TU Daxi, JIANG Yuhao, XU Cheng, YU Linchen   

  1. School of Computer Science, China University of Geosciences, Wuhan Hubei 430074, China
  • Received:2018-09-10 Revised:2018-10-26 Online:2019-04-10 Published:2019-04-10
  • Supported by:
    This work is partially supported by the National Natural Science Foundation of China (61502439).

摘要: 针对在动态网络环境和有限缓存容量限制下用户观看视频体验质量低的问题,提出一种综合考虑带宽和缓存因素的动态自适应的HTTP流码率渐进切换(DASBS)算法。首先,利用滑动窗口分析最近下载分片得到带宽初步估值;然后,依据实时带宽波动程度和缓存状态设置双矫正因子进一步平滑带宽估值;最后,设置缓存阈值使其与当前码率建立相关关系,并利用带宽估值和缓存动态阈值共同控制码率切换。使用libdash平台验证算法性能,DASBS在切换平滑性上优于VQCQ(Video Quality Control for QoE)算法,视频播放平均码率更高,有效提高了带宽利用率;平均码率稍低于EABS(Evolution of Adaptive Bitrate Switching)算法时,切换次数得到大幅下降,整体切换稳定性表现更优。实验结果表明,所提算法在动态网络环境中具有带宽高利用、切换平滑和切换稳定的良好表现,能够有效改善用户体验。

关键词: 流媒体, 码率自适应, 网络带宽, 缓存容量, 渐进切换

Abstract: Aiming at the problem of low quality of video viewing experience in dynamic network environment with limited cache capacity, a Dynamic Adaptive Step-wise Bitrate Switching (DASBS) algorithm for HTTP streaming considering network bandwidth and cache capacity was proposed. Firstly, a sliding window was used to analyze the recent downloaded fragments, obtaining the initial bandwidth estimation. Then, according to the real-time bandwidth fluctuation degree and cache state, two correction factors were set to further smooth the bandwidth estimation. Finally, a cache threshold was set to establish a correlation with the current bitrate, and the bandwidth estimation and the cache dynamic threshold were used to jointly control the bitrate switching. Experimental results on platform libdash show that DASBS is better than Video Quality Control for QoE (VQCQ) algorithm in switching smoothness and its average bitrate of video playback is higher, which effectively improves the bandwidth utilization. Although the average bitrate is slightly lower than that of Evolution of Adaptive Bitrate Switching (EABS) algorithm, the number of switching times is greatly reduced, improving the switching stability. The experimental results show that the proposed algorithm has high bandwidth utilization, switching smoothness and switching stability in dynamic network environment, which can effectively improve user experience.

Key words: streaming media, bitrate adaptation, network bandwidth, cache capacity, step-wise switching

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