基于DASH协议的自适应流媒体传输技术研究

发布时间：2019-02-21 12:37

【摘要】：随着互联网的普及和移动通信技术的迅猛发展,以多媒体技术为载体的流媒体应用越来越广泛。传统的Internet可有效地完成文字、图形等离散媒体的传输,却在传送大量实时连续的音视频媒体数据时面临巨大挑战。以流的方式对实时连续的数据进行传送可以很好的应对这一挑战。然而,随着流媒体应用的持续增长,传统的流媒体技术在实际中呈现了各种各样的不足之处,如网络异构、无法通过防火墙、服务器部署复杂、维护成本高等问题。基于MPEG-DASH协议的流媒体技术结合HTTP渐进式下载技术与自适应传输技术的优点,可以优化这些问题。本文主要研究基于DASH协议的流媒体自适应系统及其关键技术。本文首先阐述了流媒体技术在其应用需求不断扩大的背景下面临的挑战,从而指出了应对这一挑战的自适应流媒体传输技术。接着研究了流媒体系统架构、协议栈以及DASH技术标准规定的媒体描述文件格式及切片原理。之后本文从搭建简单的自适应流媒体系统着手,研究该系统中客户端播放器内置的自适应码率选择算法,指出了其内置的算法在选择最佳码率时存在的不足。然后针对自适应码率选择算法这一问题的优化,对客户端自适应传输算法的数学模型进行研究,在此基础上设计了一种将速率和客户端缓冲区结合的自适应码率选择算法。最后,在NS-3中,针对固定网络带宽场景和带宽变化场景,对已有渐近切换算法和设计的算法进行实验,并比较二者的综合性能。仿真结果表明,在固定网络带宽场景下,设计的算法具有稳定的高速率,播放可行;在带宽变化场景下,设计的算法表现出了良好的自适应性,不仅提高了网络带宽利用率,而且提高了用户的视频体验质量。
[Abstract]:With the popularization of the Internet and the rapid development of mobile communication technology, streaming media with multimedia technology as the carrier is more and more widely used. Traditional Internet can transmit text, graphics and other discrete media effectively, but it faces a great challenge in transmitting a large number of real-time and continuous audio and video media data. This challenge can be well met by stream transmission of real-time and continuous data. However, with the continuous growth of streaming media applications, the traditional streaming media technology presents a variety of shortcomings in practice, such as heterogeneous network, unable to pass through the firewall, complex server deployment, high maintenance costs and so on. Streaming media technology based on MPEG-DASH protocol can optimize these problems by combining the advantages of HTTP progressive download technology and adaptive transmission technology. This paper mainly studies the streaming media adaptive system based on DASH protocol and its key technology. This paper first describes the challenges facing streaming media technology under the background of its expanding application requirements, and then points out the adaptive streaming media transmission technology to deal with this challenge. Then, the architecture of streaming media system, the protocol stack and the format and slicing principle of media description file stipulated by DASH technology standard are studied. Then this paper starts with building a simple adaptive streaming media system, studies the adaptive rate selection algorithm built in the client player, and points out the shortcomings of the built-in algorithm in selecting the best bit rate. Then, aiming at the optimization of the adaptive rate selection algorithm, the mathematical model of the client adaptive transmission algorithm is studied, and an adaptive rate selection algorithm combining the rate with the client buffer is designed. Finally, in NS-3, for the fixed network bandwidth scenario and bandwidth change scenario, the existing asymptotic handoff algorithm and the designed algorithm are experimented, and the comprehensive performance of the two algorithms is compared. The simulation results show that the proposed algorithm has a stable high speed and is feasible to play under the fixed network bandwidth scenario. In the scenario of bandwidth change, the proposed algorithm shows good adaptability, which not only improves the utilization of network bandwidth, but also improves the quality of user's video experience.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN919.8

【参考文献】