本文選題：ARM + Linux��； 參考：《蘭州理工大學(xué)》2017年碩士論文

【摘要】：近年來,隨著多媒體技術(shù)、無線通信技術(shù)、網(wǎng)絡(luò)技術(shù)的發(fā)展,無線視頻傳輸應(yīng)用需求快速增長。無線網(wǎng)絡(luò)接入與嵌入式系統(tǒng)設(shè)計的靈活性,為視頻傳輸設(shè)計帶來了新的更好的手段和方法,也拓展了無線網(wǎng)絡(luò)技術(shù)的應(yīng)用領(lǐng)域。本文基于無線視頻傳輸?shù)膽?yīng)用需求,將無線網(wǎng)絡(luò)技術(shù)和嵌入式系統(tǒng)相結(jié)合,研究并設(shè)計基于無線通信技術(shù)的視頻傳輸系統(tǒng)。在研究視頻編碼和解碼協(xié)議的基礎(chǔ)上,結(jié)合設(shè)計需求對比現(xiàn)有的協(xié)議和編碼器,確定系統(tǒng)采用基于H.264編解碼協(xié)議的x264編碼器;根據(jù)系統(tǒng)性能需求和價格因素的影響確定采用AM3358處理器、C525攝像頭和EC20無線模塊組成的硬件平臺;在系統(tǒng)開發(fā)環(huán)境的選擇上,通過比較Linux各發(fā)行版本的優(yōu)缺點,確定系統(tǒng)采用Debian發(fā)行版本的嵌入式開發(fā)環(huán)境,并配置相應(yīng)嵌入式開發(fā)工具和環(huán)境;通過編譯U-boot、裁剪Linux內(nèi)核、裁剪并構(gòu)建根文件系統(tǒng)等工作,將Linux操作系統(tǒng)移植到嵌入式硬件平臺。編寫視頻采集程序,通過調(diào)用視頻采集框架V4L2接口,實現(xiàn)視頻信號的采集。針對選擇的4G通訊模塊,編寫該模塊Linux驅(qū)動程序,移植PPP協(xié)議程序,使構(gòu)建的嵌入式設(shè)備接入互聯(lián)網(wǎng)。在以上工作的基礎(chǔ)上,移植x264編碼器程序,并對采集到視頻信號進行編碼,將編碼后的視頻碼流按照實時傳輸協(xié)議RTP進行打包。利用內(nèi)網(wǎng)穿透技術(shù)將打包好的視頻文件發(fā)送到服務(wù)器端PC上,通過PC上的VLC播放器顯示傳輸視頻信息。針對采用x264碼率控制算法ABR控制碼率時會出現(xiàn)較大誤差的問題,對其源碼進行分析,找出碼率控制不精確的原因。根據(jù)碼率控制特點,研究并采用模糊控制方法對碼率控制進行優(yōu)化,在此基礎(chǔ)上針對ABR算法設(shè)計模糊控制器,并給出優(yōu)化結(jié)果。搭建實驗測試平臺進行測試,測試結(jié)果表明,本系統(tǒng)可以實現(xiàn)嵌入式無線視頻傳輸功能,優(yōu)化后的ABR算法比優(yōu)化前更接近目標(biāo)碼率。
[Abstract]:In recent years, with the development of multimedia technology, wireless communication technology and network technology, the demand for wireless video transmission applications is growing rapidly. The flexibility of wireless network access and embedded system design not only brings new and better methods for video transmission design, but also expands the application field of wireless network technology. Based on the application requirement of wireless video transmission, this paper studies and designs a video transmission system based on wireless communication technology by combining wireless network technology with embedded system. Based on the research of video coding and decoding protocol and comparing the existing protocols and encoders with the design requirements, it is determined that the system adopts x264 encoder based on H.264 codec protocol. The hardware platform composed of AM3358 processor C525 camera and EC20 wireless module is determined according to the influence of system performance requirements and price factors. In the selection of system development environment, the advantages and disadvantages of each release version of Linux are compared. It is determined that the system adopts the embedded development environment of Debian distribution version, and the corresponding embedded development tools and environment are configured. By compiling U-boots, clipping the Linux kernel, tailoring and constructing root file system, etc. The Linux operating system is transplanted to the embedded hardware platform. The video acquisition program is written and the video signal acquisition is realized by calling the V4L2 interface of the video acquisition framework. Aiming at the selected 4G communication module, the Linux driver of the module is written and the PPP protocol program is transplanted to make the embedded device connected to the Internet. On the basis of the above work, the x264 encoder program is transplanted, and the captured video signal is encoded, and the encoded video stream is packaged according to the real-time transmission protocol RTP. The packaged video files are sent to the server PC by using the technology of intranet penetration, and the video information is displayed and transmitted by the VLC player on the PC. In order to solve the problem of large error when using x264 rate control algorithm ABR to control the rate, this paper analyzes the source code and finds out the reason for the inaccuracy of rate control. According to the characteristics of rate control, the fuzzy control method is used to optimize the rate control. Based on this, the fuzzy controller is designed for the ABR algorithm, and the optimization results are given. The test results show that the system can realize embedded wireless video transmission function and the optimized ABR algorithm is closer to the target bit rate than before optimization.
【學(xué)位授予單位】：蘭州理工大學(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：1984863