本文選題：流媒體傳輸 + 碼率自適應(yīng)��； 參考：《哈爾濱工業(yè)大學(xué)》2016年碩士論文

【摘要】：隨著“互聯(lián)網(wǎng)+”行動(dòng)計(jì)劃于2015年上升為國家戰(zhàn)略,我國互聯(lián)網(wǎng)的發(fā)展呈現(xiàn)出更加廣闊的前景。網(wǎng)絡(luò)視頻的廣泛應(yīng)用促使關(guān)鍵的流媒體傳輸技術(shù)不斷發(fā)展。流媒體傳輸在移動(dòng)互聯(lián)網(wǎng)中依然存在網(wǎng)絡(luò)抖動(dòng)、智能移動(dòng)設(shè)備性能差異等問題。自適應(yīng)流媒體傳輸技術(shù)是目前最前沿和最高效的解決方案之一。碼率自適應(yīng)算法是流媒體傳輸技術(shù)中的核心。目前某些算法都以某一個(gè)影響因素為主展開,并且只在仿真環(huán)境中進(jìn)行實(shí)驗(yàn),缺乏對(duì)自適應(yīng)流媒體技術(shù)的應(yīng)用開發(fā)。在分析各類型的流媒體傳輸協(xié)議以及現(xiàn)有的碼率自適應(yīng)算法后,本課題提出一種基于帶寬和緩存的碼率自適應(yīng)優(yōu)化算法,并設(shè)計(jì)實(shí)現(xiàn)了一個(gè)MPEG-DASH自適應(yīng)傳輸系統(tǒng)。本課題將MPEG-DASH標(biāo)準(zhǔn)與其它傳輸協(xié)議分別進(jìn)行縱向和橫向比較分析,并深入探討現(xiàn)有的碼率自適應(yīng)算法,分析出帶寬和客戶端本地緩存是影響基于HTTP流傳輸質(zhì)量的兩大主要因素。本課題提出基于帶寬和緩存的碼率自適應(yīng)優(yōu)化算法,通過設(shè)計(jì)優(yōu)化方程來量化帶寬和本地緩存這兩大因素�？傮w工作為首先利用帶寬預(yù)測的方法,估算分片碼率集合中可選子集的上限值。然后調(diào)整兩大因子的相關(guān)系數(shù),計(jì)算出下一個(gè)分片數(shù)據(jù)的最優(yōu)碼率質(zhì)量。最后將該算法移植到MPEG-DASH自適應(yīng)系統(tǒng)中并進(jìn)行對(duì)比實(shí)驗(yàn)。實(shí)驗(yàn)表明,該算法具有以下特點(diǎn):1)使視頻播放質(zhì)量遠(yuǎn)遠(yuǎn)超過普通的流媒體傳輸技術(shù),能在網(wǎng)絡(luò)質(zhì)量不好的情況下,流暢播放視頻;2)該算法接近或超過現(xiàn)有的自適應(yīng)算法,通過采用較低碼率質(zhì)量的媒體分片,抵消帶寬抖動(dòng)的影響,同時(shí)把本地緩存中的媒體分片長度維持在一個(gè)最小值,避免下溢導(dǎo)致的播放卡頓。本課題實(shí)現(xiàn)了一種使用自適應(yīng)優(yōu)化算法的MPEG-DASH系統(tǒng),并在實(shí)際應(yīng)用場景下對(duì)該系統(tǒng)進(jìn)行性能評(píng)測。該系統(tǒng)具有以下特點(diǎn):1)采取“瀏覽器/服務(wù)器”架構(gòu),結(jié)合HTML5技術(shù),以解決移動(dòng)互聯(lián)網(wǎng)環(huán)境中出現(xiàn)的不兼容、不穩(wěn)定等問題;2)借助優(yōu)化的碼率自適應(yīng)算法,克服了網(wǎng)絡(luò)抖動(dòng)、設(shè)備性能差異等問題,最大限度地利用帶寬資源傳輸流媒體,提供盡可能好的網(wǎng)絡(luò)視頻服務(wù)質(zhì)量。參考MPEG-DASH協(xié)議規(guī)范與應(yīng)用場景,通過PC和移動(dòng)終端兩種不同設(shè)備、不同數(shù)量的碼率分片組合以及不同的分片時(shí)長等三組對(duì)比實(shí)驗(yàn),得出使系統(tǒng)自適應(yīng)性能最優(yōu)的參數(shù)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.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TN919.8
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本文編號(hào)：1760437