本文選題：ARM + 嵌入式Linux　； 參考：《杭州電子科技大學(xué)》2012年碩士論文

【摘要】：隨著互聯(lián)網(wǎng)技術(shù)的發(fā)展，網(wǎng)絡(luò)的帶寬越來越高，城市中ADSL等寬帶網(wǎng)絡(luò)變得普及�；诰W(wǎng)絡(luò)的各種應(yīng)用需求應(yīng)運而生，對網(wǎng)絡(luò)多媒體信息的需要也越來越大了。多媒體編解碼技術(shù)的發(fā)展，新的編解碼方式使得音視頻文件在保證清晰度的情況下，提高了壓縮率，大大降低了文件的大小，使得其更適合網(wǎng)絡(luò)傳輸了。流媒體技術(shù)是指視頻、音頻和文字等多媒體數(shù)據(jù)以連續(xù)流方式順序從信息源端向目的地傳輸，目的地在接收到數(shù)據(jù)并進行短暫緩存后就立即播放的一種多媒體技術(shù)。流媒體技術(shù)采用流式傳輸?shù)姆绞絺鬏敂?shù)據(jù)。它并不下載整個完整的文件，具有邊下載邊播放的特點。一開始只是傳輸部分的多媒體數(shù)據(jù)，流媒體客戶端將接收的數(shù)據(jù)放入緩存中，同時播放器就開始播放。流媒體技術(shù)在安防監(jiān)控、網(wǎng)絡(luò)電視、視頻會議等應(yīng)用領(lǐng)域都起著重要的作用，為人們的工作生活帶來了便利。 嵌入式流媒體服務(wù)器不同于傳統(tǒng)的基于PC架構(gòu)的流媒體服務(wù)器，嵌入式的流媒體服務(wù)器建立于一體化的硬件結(jié)構(gòu)之上，具有可移動性好，專業(yè)化高，穩(wěn)定性好，，實時性高的優(yōu)點，因而越來越多的廠商開始關(guān)注于嵌入式流媒體產(chǎn)品的開發(fā)。正是由于市場上對于嵌入式產(chǎn)品的需求，本文主要研究了流媒體的實時傳輸原理與協(xié)議，構(gòu)建了一個能夠進行音視頻采集、編碼壓縮、網(wǎng)絡(luò)傳輸以及解碼播放的完整流媒體服務(wù)系統(tǒng)。流媒體服務(wù)器建立在基于ARM處理器HI3515的嵌入式平臺之上，而客戶端的解碼播放則是在PC平臺上實現(xiàn)的。 本文對嵌入式HI3515平臺進行了深入研究，基于HI3515平臺進行嵌入式軟件的開發(fā)設(shè)計。構(gòu)建了HI3515的交叉編譯的開發(fā)環(huán)境與嵌入式Linux操作系統(tǒng)。本文在設(shè)計流媒體服務(wù)傳輸系統(tǒng)時，選用實時流媒體協(xié)議（RTSP）來實現(xiàn)服務(wù)器與客戶端之間的控制信息的交互傳輸，根據(jù)RTSP協(xié)議來進行多用戶連接的管理與流控制。實現(xiàn)端對端的實時數(shù)據(jù)的網(wǎng)絡(luò)傳輸要依據(jù)實時傳輸協(xié)議（RTP），特別對H.264編碼的視頻數(shù)據(jù)與G.711編碼的音頻數(shù)據(jù)的網(wǎng)絡(luò)傳輸格式進行了研究。當傳輸?shù)牧髅襟w中既有視頻數(shù)據(jù)又有音頻數(shù)據(jù)時，需要考慮音頻與視頻之間的同步問題，通過實時流媒體控制協(xié)議（RTCP）在數(shù)據(jù)發(fā)送時進行控制，調(diào)整發(fā)送時RTP中的時間戳來消除音視頻流不同步的情況。設(shè)計HTTP協(xié)議，嵌入式設(shè)備己接入網(wǎng)絡(luò)的情況下，通過PC端的瀏覽器來訪問嵌入式設(shè)備的IP地址，下載放置在嵌入式設(shè)備指定目錄下的Web頁面與播放器插件。用戶在Web頁面上進行參數(shù)設(shè)置，通過HTTP協(xié)議發(fā)送給設(shè)備，實現(xiàn)對設(shè)備的控制，同時播放插件對音視頻解碼播放，實現(xiàn)實時同步播放。最后對整個系統(tǒng)的功能的實現(xiàn)情況與各個性能指標進行測試，達到了實際應(yīng)用中所要求的指標，完成了設(shè)計的目標。
[Abstract]:With the development of Internet technology, the bandwidth of network becomes higher and higher, and broadband networks such as ADSL become popular in cities.Various applications based on network emerge as the times require, and the need for network multimedia information is growing.With the development of multimedia coding and decoding technology, the new encoding and decoding method makes the audio and video files improve the compression ratio and greatly reduce the size of the files, which makes them more suitable for network transmission.Streaming media technology is a multimedia technology in which multimedia data, such as video, audio and text, are transmitted from the source to the destination in the order of continuous flow, and the destination plays the data immediately after receiving the data and caching briefly.Streaming media technology adopts streaming transmission mode to transmit data.It does not download the entire file, with download while playing features.In the beginning, the streaming media client puts the received data into the cache and the player begins to play.Streaming media technology plays an important role in security monitoring, network television, video conferencing and other applications, which brings convenience to people's work and life.The embedded streaming media server is different from the traditional streaming media server based on PC. The embedded streaming media server is based on the integrated hardware structure, which has good mobility, high specialization and good stability.Therefore, more and more manufacturers begin to pay attention to the development of embedded streaming media products.Because of the demand of embedded products in the market, this paper mainly studies the real-time transmission principle and protocol of streaming media, and constructs a audio and video collection, coding and compression.A complete streaming media service system for network transmission and decoding and playback.The streaming media server is built on the embedded platform based on the ARM processor HI3515, and the client decoding and playing is implemented on the PC platform.In this paper, the embedded HI3515 platform is deeply studied, and the embedded software is developed based on HI3515 platform.The development environment of cross compiling of HI3515 and embedded Linux operating system are constructed.In the design of streaming media service transmission system, the real-time streaming media protocol (RTSP) is used to realize the interactive transmission of control information between the server and the client. According to the RTSP protocol, the multi-user connection management and flow control are carried out.The network transmission of end-to-end real-time data should be based on the real-time transmission protocol, especially the network transmission format of H.264 encoded video data and G.711 encoded audio data.When there are both video data and audio data in the streaming media, the synchronization between audio and video should be considered, and the real-time streaming media control protocol (RTCPP) is used to control the transmission of data.Adjust the timestamp in the RTP at the time of sending to eliminate the synchronization of audio and video streams.The HTTP protocol is designed. When embedded devices are connected to the network, the IP address of embedded devices is accessed through the browser of PC, and the Web pages and player plug-ins placed in the specified directory of embedded devices are downloaded.The user sets the parameters on the Web page, sends them to the device through HTTP protocol, realizes the control of the device, and simultaneously plays the audio and video decoding and playing by the plug-in, and realizes the real-time synchronous play.Finally, the realization of the whole system function and the performance index are tested, which reach the requirements of practical application and achieve the goal of the design.
【學(xué)位授予單位】：杭州電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TP368.1;TN919.8

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本文編號：1761936