【摘要】：隨著互聯(lián)網(wǎng)的普及和移動通信技術的迅猛發(fā)展,以多媒體技術為載體的流媒體應用越來越廣泛。傳統(tǒng)的Internet可有效地完成文字、圖形等離散媒體的傳輸,卻在傳送大量實時連續(xù)的音視頻媒體數(shù)據(jù)時面臨巨大挑戰(zhàn)。以流的方式對實時連續(xù)的數(shù)據(jù)進行傳送可以很好的應對這一挑戰(zhàn)。然而,隨著流媒體應用的持續(xù)增長,傳統(tǒng)的流媒體技術在實際中呈現(xiàn)了各種各樣的不足之處,如網(wǎng)絡異構(gòu)、無法通過防火墻、服務器部署復雜、維護成本高等問題�；贛PEG-DASH協(xié)議的流媒體技術結(jié)合HTTP漸進式下載技術與自適應傳輸技術的優(yōu)點,可以優(yōu)化這些問題。本文主要研究基于DASH協(xié)議的流媒體自適應系統(tǒng)及其關鍵技術。本文首先闡述了流媒體技術在其應用需求不斷擴大的背景下面臨的挑戰(zhàn),從而指出了應對這一挑戰(zhàn)的自適應流媒體傳輸技術。接著研究了流媒體系統(tǒng)架構(gòu)、協(xié)議棧以及DASH技術標準規(guī)定的媒體描述文件格式及切片原理。之后本文從搭建簡單的自適應流媒體系統(tǒng)著手,研究該系統(tǒng)中客戶端播放器內(nèi)置的自適應碼率選擇算法,指出了其內(nèi)置的算法在選擇最佳碼率時存在的不足。然后針對自適應碼率選擇算法這一問題的優(yōu)化,對客戶端自適應傳輸算法的數(shù)學模型進行研究,在此基礎上設計了一種將速率和客戶端緩沖區(qū)結(jié)合的自適應碼率選擇算法。最后,在NS-3中,針對固定網(wǎng)絡帶寬場景和帶寬變化場景,對已有漸近切換算法和設計的算法進行實驗,并比較二者的綜合性能。仿真結(jié)果表明,在固定網(wǎng)絡帶寬場景下,設計的算法具有穩(wěn)定的高速率,播放可行;在帶寬變化場景下,設計的算法表現(xiàn)出了良好的自適應性,不僅提高了網(wǎng)絡帶寬利用率,而且提高了用戶的視頻體驗質(zhì)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.
【學位授予單位】：南京郵電大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN919.8

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本文編號：2427504