【摘要】：近年來,虛擬桌面技術(shù)日益蓬勃,更加迅速而深刻地改變著我們的世界,無論是對于企業(yè)還是個(gè)人都得到了廣泛地應(yīng)用,遠(yuǎn)程桌面連接是其關(guān)鍵技術(shù)之一。虛擬桌面的基本原理是:在遠(yuǎn)端服務(wù)器上統(tǒng)一生成配置虛擬桌面,客戶端采用某種遠(yuǎn)程桌面連接技術(shù)訪問虛擬桌面。現(xiàn)行的大部分客戶端能夠較好地支持普通桌面操作,比如鼠標(biāo)、鍵盤輸入等,但是遠(yuǎn)程觀看虛擬桌面中流媒體的用戶體驗(yàn)還有待提升。VNC的跨平臺性和開源性使VNC平臺成為了本文研究的首選。本文首先對VNC采用的RFB協(xié)議進(jìn)行了詳細(xì)的分析,比如屏幕更新方式以及消息交互機(jī)制等等,總結(jié)出了 VNC在流媒體傳輸方面的缺陷和不足。隨后從服務(wù)端和客戶端兩方面提出了一套系統(tǒng)性的優(yōu)化策略。在服務(wù)端,本文從遠(yuǎn)程虛擬桌面流媒體的識別出發(fā),針對其“懶惰式”的屏幕更新方式,提出服務(wù)端主動推送的策略,并且針對其編碼方式壓縮率低的缺陷擴(kuò)展了 H.264編碼。對于服務(wù)端編碼推送數(shù)據(jù)速度和客戶端解碼處理數(shù)據(jù)速度不匹配的矛盾,本文設(shè)計(jì)了碼率控制模塊來對服務(wù)端編碼速度進(jìn)行控制。另外,本文還針對基于共享機(jī)制的多媒體文件服務(wù)器上的流媒體文件設(shè)計(jì)了大文件點(diǎn)播機(jī)制,以滿足用戶對分辨率清晰度的需求。在客戶端,對應(yīng)服務(wù)端的一系列優(yōu)化,首先移植增加了 FFmpeg解碼模塊來解碼H.264編碼的數(shù)據(jù)�？紤]到Android設(shè)備資源和解碼能力有限的問題,本文在客戶端增加了硬解碼模塊。當(dāng)硬解碼無法緩解客戶端CPU的壓力時(shí),客戶端啟用反饋?zhàn)儞Q模塊向服務(wù)端發(fā)出碼率控制的請求。最后,嵌入Vitamio框架多媒體播放器實(shí)現(xiàn)了大文件點(diǎn)播機(jī)制中本地播放的功能。為了驗(yàn)證上述優(yōu)化方案的性能提升,本文進(jìn)行了針對性測試,分別在服務(wù)端和客戶端兩個(gè)方面與VNC原型系統(tǒng)進(jìn)行對比,并模擬了在不同網(wǎng)絡(luò)環(huán)境和不同設(shè)備配置場景下優(yōu)化版VNC平臺的運(yùn)行狀況。對比結(jié)果表明,本文提出的流媒體傳輸?shù)膬?yōu)化改進(jìn)方案可以使基于VNC平臺的遠(yuǎn)程播放流媒體的性能得到提高,用戶體驗(yàn)獲得提升。
[Abstract]:In recent years, the virtual desktop technology is booming day by day, and it is changing our world more rapidly and profoundly. It is widely used for both enterprises and individuals, and remote desktop connection is one of its key technologies. The basic principle of virtual desktop is to generate and configure virtual desktop uniformly on the remote server, and the client uses some remote desktop connection technology to access the virtual desktop. Most of the current clients can support normal desktop operations, such as mouse, keyboard input, etc. However, the user experience of remote viewing streaming media in virtual desktop still needs to be improved. The cross-platform and open-source of VNC make the VNC platform become the first choice in this paper. In this paper, the RFB protocol adopted by VNC is analyzed in detail, such as screen update mode and message interaction mechanism, etc., and the shortcomings and shortcomings of VNC in streaming media transmission are summarized. Then a systematic optimization strategy is put forward from two aspects: server side and client side. On the server side, starting from the identification of remote virtual desktop streaming media, aiming at the lazy screen update mode, this paper puts forward the active push strategy of the server side, and extends H. 264 coding according to the low compression ratio of its coding mode. In this paper, a rate control module is designed to control the encoding speed of the server for the contradiction of the mismatch between the encoding and pushing data speed of the server and the decoding and processing speed of the client. In addition, this paper also designed a large file-on-demand mechanism for streaming media files on multimedia file server based on sharing mechanism to meet the users' demand for resolution clarity. On the client side, corresponding to a series of optimizations on the server side, the FFmpeg decoding module is added to decode H. 264 encoded data. Considering the limited resource and decoding ability of Android, a hard decoding module is added to the client. When hard decoding can not relieve the pressure of client CPU, the client enables feedback conversion module to send a rate control request to the server. Finally, embedded Vitamio framework multimedia player realizes the function of local playing in large file on demand mechanism. In order to verify the performance improvement of the above optimization scheme, this paper carries on the targeted test, and compares with the VNC prototype system in the server side and the client side, respectively. And simulate the operation of the optimized version of VNC platform in different network environment and different device configuration scenario. The comparison results show that the performance of remote streaming media based on VNC platform can be improved and the user experience can be improved by the optimization and improvement scheme of streaming media transmission proposed in this paper.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN919.8

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本文編號：2431585