基于HTTP的动态自适应流媒体技术的研究
发布时间：2018-12-29 07:27
【摘要】：基于HTTP的动态自适应流媒体技术,主要是根据网络状况以及设备性能动态调整播放媒体文件的码率,实现多媒体内容的无缝传送和播放。码率自适应算法作为动态自适应流媒体技术的关键,一直是学术界的一个研究热点。通过对现有码率自适应算法进行分析后发现:(1)基于带宽的码率自适应算法在播放开始时会长时间选择码率较低的切片进行下载,导致带宽利用率较低;(2)基于缓存的码率自适应算法对带宽变化比较敏感,容易造成频繁和大幅度的码率切换,严重影响用户体验质量;(3)基于缓冲区等级的码率自适应算法,在播放开始阶段的切片码率提升较慢,并且在带宽波动较大的环境下,客户端缓冲区变化幅度较大。鉴于目前的算法存在上述问题,对码率自适应算法的研究也显得至关重要。本文首先研究了基于HTTP的自适应流媒体技术的主要特点,并对现有自适应流媒体技术的企业方案进行了介绍和分析。其次,本文重点研究了旨在为动态自适应流媒体技术提供统一标准的MPEG-DASH及其相关技术。然后,本文对现有码率自适应算法进行了研究和分析,并针对算法目前存在的问题,提出了一种基于缓冲区等级的改进算法。该算法在保证缓冲区状态稳定的条件下,减少了码率切换次数,提升了播放开始阶段的切片码率。同时,本文依据自适应播放过程中影响用户体验质量(Quality of Experience,Qo E)的主要因素,定义了Qo E评价指标和评价函数,并利用层次分析法确定了评价函数中不同指标的权重系数,最终实现了对自适应算法的客观评价。最后,本文在基于Android的客户端中实现了提出的改进算法以及对比算法,并利用Web服务器和网络模拟工具对算法在不同网络环境中的性能表现进行了实验验证和QoE分析。实验结果表明,本文提出的改进算法在受限的不变网络环境和连续波动的网络环境中表现相对稳定。在保证缓冲区稳定的前提下,提出的改进算法在带宽呈现阶梯状变化的网络环境下同样有着良好的性能表现。同时,通过利用Qo E评价函数对不同算法在连续波动网络环境和带宽阶梯状网络环境下的QoE值进行计算后发现,提出的改进算法在波动网络环境下能够提升用户的体验质量。
[Abstract]:The dynamic adaptive streaming media technology based on HTTP mainly adjusts the code rate of playing media files dynamically according to the network condition and equipment performance to realize the seamless transmission and playback of multimedia content. As a key technology of dynamic adaptive streaming media, rate adaptive algorithm has been a hot research topic in academia. Through the analysis of the existing rate adaptive algorithm, we find that: (1) the bandwidth based rate adaptive algorithm will select the lower bit rate slice to download at the beginning of playback, which leads to low bandwidth utilization; (2) the rate adaptive algorithm based on cache is sensitive to bandwidth change, and it is easy to cause frequent and large rate switching, which seriously affects the quality of user experience. (3) the bit-rate adaptive algorithm based on buffer level increases the bit rate slowly at the beginning stage of playback, and the client-side buffer varies greatly in the environment of high bandwidth fluctuation. In view of the above problems in the current algorithm, it is very important to study the rate adaptive algorithm. In this paper, the main characteristics of adaptive streaming media technology based on HTTP are studied, and the enterprise solutions of the existing adaptive streaming media technology are introduced and analyzed. Secondly, this paper focuses on MPEG-DASH and its related technologies, which aim to provide uniform standard for dynamic adaptive streaming media technology. Then, the existing rate adaptive algorithm is studied and analyzed, and an improved algorithm based on buffer level is proposed to solve the existing problems of the algorithm. Under the condition that the buffer state is stable, the algorithm reduces the number of bit rate switching and improves the slice rate at the beginning stage of playback. At the same time, according to the main factors that affect the user experience quality (Quality of Experience,Qo E) in the process of adaptive playback, the evaluation index and function of Qo E are defined. The weight coefficients of different indexes in the evaluation function are determined by using the analytic hierarchy process (AHP), and the objective evaluation of the adaptive algorithm is finally realized. Finally, the improved algorithm and the contrast algorithm are implemented in the client based on Android, and the performance of the algorithm in different network environment is verified and analyzed by using Web server and network simulation tools. The experimental results show that the proposed improved algorithm is relatively stable in the restricted invariant network environment and the continuous fluctuating network environment. On the premise of ensuring buffer stability, the proposed improved algorithm also has a good performance in the network environment where the bandwidth of the network presents ladder changes. At the same time, by using the Qo E evaluation function to calculate the QoE values of different algorithms in the continuous fluctuating network environment and the bandwidth ladder network environment, it is found that the improved algorithm can improve the user's experience quality in the fluctuating network environment.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN919.8
[Abstract]:The dynamic adaptive streaming media technology based on HTTP mainly adjusts the code rate of playing media files dynamically according to the network condition and equipment performance to realize the seamless transmission and playback of multimedia content. As a key technology of dynamic adaptive streaming media, rate adaptive algorithm has been a hot research topic in academia. Through the analysis of the existing rate adaptive algorithm, we find that: (1) the bandwidth based rate adaptive algorithm will select the lower bit rate slice to download at the beginning of playback, which leads to low bandwidth utilization; (2) the rate adaptive algorithm based on cache is sensitive to bandwidth change, and it is easy to cause frequent and large rate switching, which seriously affects the quality of user experience. (3) the bit-rate adaptive algorithm based on buffer level increases the bit rate slowly at the beginning stage of playback, and the client-side buffer varies greatly in the environment of high bandwidth fluctuation. In view of the above problems in the current algorithm, it is very important to study the rate adaptive algorithm. In this paper, the main characteristics of adaptive streaming media technology based on HTTP are studied, and the enterprise solutions of the existing adaptive streaming media technology are introduced and analyzed. Secondly, this paper focuses on MPEG-DASH and its related technologies, which aim to provide uniform standard for dynamic adaptive streaming media technology. Then, the existing rate adaptive algorithm is studied and analyzed, and an improved algorithm based on buffer level is proposed to solve the existing problems of the algorithm. Under the condition that the buffer state is stable, the algorithm reduces the number of bit rate switching and improves the slice rate at the beginning stage of playback. At the same time, according to the main factors that affect the user experience quality (Quality of Experience,Qo E) in the process of adaptive playback, the evaluation index and function of Qo E are defined. The weight coefficients of different indexes in the evaluation function are determined by using the analytic hierarchy process (AHP), and the objective evaluation of the adaptive algorithm is finally realized. Finally, the improved algorithm and the contrast algorithm are implemented in the client based on Android, and the performance of the algorithm in different network environment is verified and analyzed by using Web server and network simulation tools. The experimental results show that the proposed improved algorithm is relatively stable in the restricted invariant network environment and the continuous fluctuating network environment. On the premise of ensuring buffer stability, the proposed improved algorithm also has a good performance in the network environment where the bandwidth of the network presents ladder changes. At the same time, by using the Qo E evaluation function to calculate the QoE values of different algorithms in the continuous fluctuating network environment and the bandwidth ladder network environment, it is found that the improved algorithm can improve the user's experience quality in the fluctuating network environment.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN919.8
【参考文献】
相关期刊论文 前6条
1 卜春芬;;基于层次分析法的教师教学质量评价研究[J];昆明学院学报;2016年06期
2 陈晓峰;;OTT传输技术选择分析[J];电视技术;2015年10期
3 施唯佳;蒋力;贾立鼎;;OTT TV和IPTV的技术比较分析[J];电信科学;2014年05期
4 常建娥;蒋太立;;层次分析法确定权重的研究[J];武汉理工大学学报(信息与管理工程版);2007年01期
5 高e，
本文编号：2394491
本文链接：https://www.wllwen.com/kejilunwen/xinxigongchenglunwen/2394491.html
