本文選題：無線音視頻通信 + C/S�。� 參考：《杭州電子科技大學(xué)》2012年碩士論文

【摘要】：隨著嵌入式技術(shù)和無線通信技術(shù)的迅速發(fā)展，特別是3G時(shí)代的到來和無線WiFi技術(shù)的廣泛應(yīng)用，為嵌入式無線音視頻通信提供了有效的途徑。然而對(duì)于普通用戶來說，基于3G的可視電話給他們?cè)O(shè)定了兩道門檻：一是高端的手機(jī)，，二是昂貴的資費(fèi)。針對(duì)這一點(diǎn)，本文實(shí)現(xiàn)了基于WiFi技術(shù)和嵌入式Linux的低成本音視頻通信方案。在此方案中，硬件平臺(tái)采用S3C2440A ARM9開發(fā)板外接RT2571W WiFi模塊；操作系統(tǒng)采用嵌入式Linux2.6.29；網(wǎng)絡(luò)傳輸采用無線AP（Access Point）接入結(jié)合以太網(wǎng)傳輸?shù)姆绞剑煌ㄐ畔到y(tǒng)采用C/S加P2P的網(wǎng)絡(luò)架構(gòu)，C/S架構(gòu)下主要完成客戶端與服務(wù)器之間各種信令的交互（例如注冊(cè)、登錄等信令及其應(yīng)答），P2P架構(gòu)下主要完成客戶端與客戶端之間音視頻通信過程中語音和視頻數(shù)據(jù)的點(diǎn)對(duì)點(diǎn)傳輸。 本文的主要工作是設(shè)計(jì)和實(shí)現(xiàn)了音視頻通信系統(tǒng)的架構(gòu)和軟件，包括服務(wù)器軟件和客戶端軟件。服務(wù)器軟件采用應(yīng)用程序服務(wù)器與MySql數(shù)據(jù)庫(kù)服務(wù)器相結(jié)合，提供客戶端用戶信息的驗(yàn)證、存儲(chǔ)以及各種信令的應(yīng)答、轉(zhuǎn)發(fā)等功能�？蛻舳塑浖潜疚牡墓ぷ髦攸c(diǎn)，它是基于嵌入式Linux和Qt/Embedded開發(fā)的嵌入式軟件，運(yùn)用了音視頻采集與壓縮編碼技術(shù)、同步技術(shù)以及網(wǎng)絡(luò)傳輸技術(shù)，實(shí)現(xiàn)了音視頻實(shí)時(shí)同步通信。 主要研究工作歸結(jié)為以下幾點(diǎn)： 1、實(shí)現(xiàn)了基于Video4Linux2的視頻采集，研究了MJPEG視頻壓縮算法，并根據(jù)前后幀圖像變化檢測(cè)的方法以及幀間壓縮的思想，提出了基于變化區(qū)域檢測(cè)提取的MJPEG改進(jìn)算法，該改進(jìn)算法在背景不變或存在背景短暫不變（比如視頻通信時(shí)攝像頭是靜止的）的場(chǎng)合下能大大增加壓縮率，減少壓縮時(shí)間。 2、研究并實(shí)現(xiàn)了基于G.729B壓縮算法的語音軟件壓縮方案和基于AMBE-2000壓縮芯片的語音硬件壓縮方案。對(duì)前者的工作有：實(shí)現(xiàn)在OSS音頻編程接口上的語音數(shù)據(jù)的采集，研究了G.729B算法并對(duì)其標(biāo)準(zhǔn)C源碼進(jìn)行了優(yōu)化來減少其算法復(fù)雜度。對(duì)后者的工作有：AMBE-2000語音模塊的電路設(shè)計(jì)、驅(qū)動(dòng)的編寫以及相應(yīng)應(yīng)用程序的實(shí)現(xiàn)。比較并分析了上述兩種方案，最終在客戶端軟件開發(fā)中采用了軟件壓縮方案。 3、從語音視頻的采集、發(fā)送、接收和播放四個(gè)環(huán)節(jié)研究并實(shí)現(xiàn)了音視頻同步技術(shù)。對(duì)網(wǎng)絡(luò)傳輸技術(shù)做了研究，包括基于NAT穿透之UDP打洞技術(shù)實(shí)現(xiàn)了處于不同私網(wǎng)網(wǎng)段的客戶端之間的P2P數(shù)據(jù)傳輸和自定義了方便簡(jiǎn)捷的通信協(xié)議。 結(jié)合上述相關(guān)技術(shù)及Qt/Embedded圖形開發(fā)框架實(shí)現(xiàn)了美觀的可視化客戶端軟件。 將客戶端軟件移植到ARM平臺(tái)上，搭建了測(cè)試環(huán)境，最終實(shí)現(xiàn)了效果較好的無線音視頻通信。
[Abstract]:With the rapid development of embedded technology and wireless communication technology, especially the arrival of 3G era and the wide application of wireless WiFi technology, it provides an effective way for embedded wireless audio and video communication. For ordinary users, however, 3G videophone sets two barriers: high-end phones and expensive tariffs. In view of this, this paper realizes the low cost audio and video communication scheme based on WiFi technology and embedded Linux. In this scheme, the hardware platform adopts the RT2571W WiFi module of S3C2440A ARM9 development board, the operating system adopts embedded Linux 2.6.29, the network transmission adopts wireless AP(Access point) access and Ethernet transmission. The communication system adopts the network architecture of C / S plus P2P. Under the architecture of C / S, the communication system mainly completes the interaction of various signaling between the client and the server (for example, registration, registration). Under the P2P architecture of signalling and answering such as login, the point-to-point transmission of voice and video data between client and client is mainly completed in the process of audio and video communication between client and client. The main work of this paper is to design and implement the architecture and software of audio and video communication system, including server software and client software. The server software combines the application server with the MySql database server to provide the functions of client user information verification, storage, response and forwarding of all kinds of signaling. Client software is the focus of this paper. It is an embedded software based on embedded Linux and Qt/Embedded. It uses audio and video acquisition and compression coding technology, synchronization technology and network transmission technology to realize real-time audio and video synchronous communication. The main research work can be summarized as follows: 1. The video acquisition based on Video4Linux2 is realized. The algorithm of MJPEG video compression is studied. According to the method of detecting the change of frame image and the idea of compression between frames, an improved MJPEG algorithm based on the detection of change region is proposed. The improved algorithm can greatly increase the compression ratio and reduce the compression time when the background is invariant or the background is temporary invariant (for example, the camera is still in video communication). 2. The speech software compression scheme based on G.729B compression algorithm and the speech hardware compression scheme based on AMBE-2000 compression chip are studied and implemented. The work of the former is as follows: to realize the acquisition of voice data on the OSS audio programming interface, the G.729B algorithm is studied and its standard C source code is optimized to reduce the complexity of the algorithm. The work of the latter includes the design of the circuit of the voice module: AMBE-2000, the design of the driver and the realization of the corresponding application program. The two schemes mentioned above are compared and analyzed. Finally, the software compression scheme is adopted in the client software development. 3. The audio and video synchronization technology is studied and realized from four links: audio and video acquisition, transmission, reception and playback. In this paper, the network transmission technology is studied, including UDP hole drilling technology based on NAT penetration to realize P2P data transmission between clients in different private network segments, and a convenient and simple communication protocol is defined. Combined with the above related technology and Qt/Embedded graphics development framework, the visual client software is realized. The client software is transplanted to the ARM platform, and the test environment is built. Finally, a better wireless audio and video communication is realized.
【學(xué)位授予單位】：杭州電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2012
【分類號(hào)】：TN914;TP368.1

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本文編號(hào)：1871995