基于DASH的自适应流媒体传输技术研究与实现

发布时间：2018-04-16 20:20

  本文选题：流媒体传输 + 码率自适应　； 参考：《哈尔滨工业大学》2016年硕士论文

【摘要】：随着“互联网+”行动计划于2015年上升为国家战略,我国互联网的发展呈现出更加广阔的前景。网络视频的广泛应用促使关键的流媒体传输技术不断发展。流媒体传输在移动互联网中依然存在网络抖动、智能移动设备性能差异等问题。自适应流媒体传输技术是目前最前沿和最高效的解决方案之一。码率自适应算法是流媒体传输技术中的核心。目前某些算法都以某一个影响因素为主展开,并且只在仿真环境中进行实验,缺乏对自适应流媒体技术的应用开发。在分析各类型的流媒体传输协议以及现有的码率自适应算法后,本课题提出一种基于带宽和缓存的码率自适应优化算法,并设计实现了一个MPEG-DASH自适应传输系统。本课题将MPEG-DASH标准与其它传输协议分别进行纵向和横向比较分析,并深入探讨现有的码率自适应算法,分析出带宽和客户端本地缓存是影响基于HTTP流传输质量的两大主要因素。本课题提出基于带宽和缓存的码率自适应优化算法,通过设计优化方程来量化带宽和本地缓存这两大因素。总体工作为首先利用带宽预测的方法,估算分片码率集合中可选子集的上限值。然后调整两大因子的相关系数,计算出下一个分片数据的最优码率质量。最后将该算法移植到MPEG-DASH自适应系统中并进行对比实验。实验表明,该算法具有以下特点:1)使视频播放质量远远超过普通的流媒体传输技术,能在网络质量不好的情况下,流畅播放视频;2)该算法接近或超过现有的自适应算法,通过采用较低码率质量的媒体分片,抵消带宽抖动的影响,同时把本地缓存中的媒体分片长度维持在一个最小值,避免下溢导致的播放卡顿。本课题实现了一种使用自适应优化算法的MPEG-DASH系统,并在实际应用场景下对该系统进行性能评测。该系统具有以下特点:1)采取“浏览器/服务器”架构,结合HTML5技术,以解决移动互联网环境中出现的不兼容、不稳定等问题;2)借助优化的码率自适应算法,克服了网络抖动、设备性能差异等问题,最大限度地利用带宽资源传输流媒体,提供尽可能好的网络视频服务质量。参考MPEG-DASH协议规范与应用场景,通过PC和移动终端两种不同设备、不同数量的码率分片组合以及不同的分片时长等三组对比实验,得出使系统自适应性能最优的参数配置值。
[Abstract]:With the action plan of "Internet" rising into national strategy in 2015, the development of Internet in China presents a broader prospect.The wide application of network video promotes the development of key streaming media transmission technology.Streaming media transmission in the mobile Internet still exists network jitter, intelligent mobile devices performance differences and other problems.Adaptive streaming media transmission technology is one of the most advanced and efficient solutions.Rate adaptive algorithm is the core of streaming media transmission technology.At present, some algorithms are mainly based on a certain factor, and only in the simulation environment, the lack of adaptive streaming media technology application development.After analyzing various kinds of streaming media transmission protocols and existing rate adaptive algorithms, this paper proposes an adaptive rate optimization algorithm based on bandwidth and cache, and designs and implements an adaptive transmission system for MPEG-DASH.In this paper, the MPEG-DASH standard and other transport protocols are compared and analyzed vertically and horizontally, and the existing rate adaptive algorithms are discussed in depth. It is found that bandwidth and client local cache are the two main factors that affect the quality of HTTP based streaming transmission.In this paper, an adaptive rate optimization algorithm based on bandwidth and cache is proposed, which quantifies bandwidth and local cache by designing optimization equations.The overall work is to estimate the upper limit value of the optional subset in the bit-rate set by using the method of bandwidth prediction.Then the correlation coefficients of the two factors are adjusted to calculate the optimal bit-rate quality of the next slice data.Finally, the algorithm is transplanted to the MPEG-DASH adaptive system and compared with the experimental results.Experiments show that the proposed algorithm has the following characteristics: 1) the video playback quality is much higher than that of the normal streaming media transmission technology, and the streaming video can be played smoothly when the network quality is not good.) the algorithm approaches or exceeds the existing adaptive algorithm.The effect of bandwidth jitter is counteracted by using low bit-rate media segments, while the length of media segments in the local cache is kept to a minimum to avoid overflowing playback.In this paper, a MPEG-DASH system using adaptive optimization algorithm is implemented, and the performance of the system is evaluated in the practical application scenario.The system has the following characteristics: 1) adopting the "browser / Server" architecture, combining with HTML5 technology to solve the problems of incompatibility and instability in the mobile Internet environment) overcoming the network jitter with the help of the optimized rate adaptive algorithm.In order to provide the best quality of network video service, the bandwidth resource is used to transmit streaming media to the maximum extent.Referring to the MPEG-DASH protocol specification and application scenario, through three groups of comparative experiments, such as PC and mobile terminal, different number of bit-rate piecewise combination and different slice duration, the parameter configuration value of the system adaptive performance is obtained.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN919.8
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本文编号：1760437