發(fā)布時間：2018-03-11 20:03

  本文選題：企業(yè)級　切入點：視頻會議　出處：《華南理工大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：視頻會議系統(tǒng)為與會者提供一個多媒體的實時交互環(huán)境,使得人們能夠遠程面對面交流,方便人們交互信息,提高工作效率,被廣泛應(yīng)用于政府、商務(wù)、教育等行業(yè)。新一代視頻會議使用互聯(lián)網(wǎng)作為傳輸平臺,能提供高清晰度視頻、音頻、文字等多種靈活的交互方式,這對傳輸過程中的帶寬、延時、抖動等參數(shù)有更高的要求。但是現(xiàn)有的互聯(lián)網(wǎng)尚不具備這樣的服務(wù)質(zhì)量保證能力。該矛盾成為當(dāng)前新一代視頻會議面臨的服務(wù)質(zhì)量挑戰(zhàn)。本文針對互聯(lián)網(wǎng)及其之上的視頻會議系統(tǒng),在企業(yè)級網(wǎng)絡(luò)的通信環(huán)境下,展開了視頻會議服務(wù)質(zhì)量保證研究。1、提出一個企業(yè)級視頻會議服務(wù)質(zhì)量保證系統(tǒng)(EVCQoS)的框架,并建立它的形式化體系結(jié)構(gòu),從數(shù)學(xué)上分析EVCQoS系統(tǒng)模型的連通性和行為特性。為網(wǎng)絡(luò)傳輸QoS和碼率適配的解決方案提供理論依據(jù)。2、以EVCQoS體系結(jié)構(gòu)為理論依據(jù),構(gòu)建一個基于網(wǎng)絡(luò)的視頻會議QoS機制。機制首先建立資源矩陣(資源模型),組織網(wǎng)絡(luò)和會議的資源,以應(yīng)對各種會議對單播、組播等資源的需求。監(jiān)視和控制企業(yè)域內(nèi)的網(wǎng)絡(luò)資源,在網(wǎng)絡(luò)的邊界使用支持SAVI的交換機來控制合法流量的進入,在網(wǎng)絡(luò)核心采用資源預(yù)約方式來管理帶寬的使用。最終實現(xiàn)視頻流的傳輸服務(wù)質(zhì)量保證。3、對于傳輸網(wǎng)絡(luò)不能提供足夠的網(wǎng)絡(luò)資源的情況,使用基于應(yīng)用層面的服務(wù)質(zhì)量保證機制,本文針對這一問題,提出了基于QoE的碼率適配算法。采用H.264 SVC對視頻編碼,利用H.264 SVC編碼算法能夠在分辨率、幀率、視頻質(zhì)量三個維度伸縮的特點,來提供視頻碼率調(diào)整手段。對于給定帶寬,使用偽主觀的神經(jīng)網(wǎng)絡(luò)模型來評估視頻的QoE質(zhì)量,根據(jù)網(wǎng)絡(luò)資源的情況,選擇最優(yōu)的編碼參數(shù)對視頻編碼,以實現(xiàn)用戶QoE的最大化。4、服務(wù)質(zhì)量保證系統(tǒng)使用神經(jīng)網(wǎng)絡(luò)QoE模型來優(yōu)化視頻編碼,也采用該模型來監(jiān)視視頻會議的運行情況。神經(jīng)網(wǎng)絡(luò)QoE模型的訓(xùn)練需要大量的主觀測試數(shù)據(jù),成本較高并且無法實時獲得。本文針對這一問題,首先研究了環(huán)境不一致情況下QoE模型的適用性問題,實驗結(jié)果顯示,在環(huán)境不一致情況下QoE預(yù)測模型的正確率明顯下降。然后提出一種QoE模型適配訓(xùn)練方法,在已經(jīng)訓(xùn)練好的QoE模型基礎(chǔ)上,使用一個線性轉(zhuǎn)換將參數(shù)矢量進行適配后再輸入ANN模型,使用較少的主觀數(shù)據(jù)能夠訓(xùn)練出應(yīng)對不同評估環(huán)境的QoE模型。基于上述研究,本文實現(xiàn)了EVCQoS系統(tǒng)。實驗結(jié)果表明,EVCQoS系統(tǒng)能夠在CERNET2上保證企業(yè)級視頻會議的傳輸服務(wù)質(zhì)量和應(yīng)用服務(wù)質(zhì)量�；诰W(wǎng)絡(luò)的QoS機制和碼率適配這兩項關(guān)鍵技術(shù)具有互補性,當(dāng)網(wǎng)絡(luò)通信資源不足而導(dǎo)致傳輸網(wǎng)絡(luò)QoS保證技術(shù)不能提供足夠資源情況,基于QoE的碼率適配技術(shù)仍能盡力保證視頻會議的服務(wù)質(zhì)量。
[Abstract]:The video conference system provides a multimedia real-time interactive environment for the participants. It enables people to communicate face to face remotely, facilitate people to exchange information, improve work efficiency, and is widely used in government and business. Education and other industries. The new generation of video conferencing uses the Internet as a transmission platform, can provide high-definition video, audio, text and other flexible interaction, this process of transmission bandwidth, delay, Jitter and other parameters have higher requirements, but the existing Internet does not yet have such a quality of service assurance capability. This contradiction has become a new generation of video conferencing facing the quality of service challenges. This paper aims at the Internet and its. Videoconferencing system based on. In the communication environment of enterprise network, the research on quality of service assurance of videoconferencing is carried out, and a framework of enterprise quality assurance system of videoconference service quality is proposed, and its formal architecture is established. The connectivity and behavior characteristics of the EVCQoS system model are analyzed mathematically. It provides a theoretical basis for the solution of network transmission QoS and bit-rate adaptation, and takes the EVCQoS architecture as the theoretical basis. A Web-based QoS mechanism for videoconferencing is constructed. Firstly, the resource matrix (resource model) is set up to organize the resources of the network and the conference, in order to deal with the unicast of all kinds of meetings. Monitor and control the network resources in the enterprise domain, use the switch supporting SAVI to control the access of the legitimate traffic at the boundary of the network. In the core of the network, resource reservation is adopted to manage the use of bandwidth. Finally, the quality of service (QoS) of video stream is guaranteed. 3, which can not provide enough network resources for the transmission network. In order to solve this problem, this paper proposes a bit-rate adaptation algorithm based on QoE, which uses H.264 SVC to encode video and H.264 SVC coding algorithm to solve this problem. For a given bandwidth, a pseudo-subjective neural network model is used to evaluate the QoE quality of video. The optimal coding parameters are selected to maximize the user's QoE. The QoS assurance system uses the neural network QoE model to optimize the video coding. The training of neural network QoE model requires a lot of subjective test data, which is expensive and can not be obtained in real time. In this paper, the applicability of QoE model under environmental inconsistency is studied. The experimental results show that the correct rate of QoE prediction model decreases obviously under the circumstance of environmental inconsistency. Then, a training method for QoE model adaptation is proposed. Based on the trained QoE model, a linear transformation is used to adapt the parameter vector and then input into the ANN model. Using less subjective data, the QoE model can be trained to deal with different evaluation environments. In this paper, the EVCQoS system is implemented. The experimental results show that the EVC QoS system can guarantee the quality of service (QoS) and application quality of service (QoS) of enterprise video conferencing on CERNET2. The two key technologies of network-based QoS mechanism and bit rate adaptation are complementary. When the network communication resources are insufficient, the transmission network QoS guarantee technology can not provide enough resources, the bit-rate adaptation technology based on QoE can still try its best to ensure the quality of service of video conference.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TN948.63;TN919.81

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