嵌入式无线视频传输系统设计

发布时间：2018-06-06 03:31

本文选题：ARM + Linux　；参考：《兰州理工大学》2017年硕士论文

【摘要】：近年来,随着多媒体技术、无线通信技术、网络技术的发展,无线视频传输应用需求快速增长。无线网络接入与嵌入式系统设计的灵活性,为视频传输设计带来了新的更好的手段和方法,也拓展了无线网络技术的应用领域。本文基于无线视频传输的应用需求,将无线网络技术和嵌入式系统相结合,研究并设计基于无线通信技术的视频传输系统。在研究视频编码和解码协议的基础上,结合设计需求对比现有的协议和编码器,确定系统采用基于H.264编解码协议的x264编码器;根据系统性能需求和价格因素的影响确定采用AM3358处理器、C525摄像头和EC20无线模块组成的硬件平台;在系统开发环境的选择上,通过比较Linux各发行版本的优缺点,确定系统采用Debian发行版本的嵌入式开发环境,并配置相应嵌入式开发工具和环境;通过编译U-boot、裁剪Linux内核、裁剪并构建根文件系统等工作,将Linux操作系统移植到嵌入式硬件平台。编写视频采集程序,通过调用视频采集框架V4L2接口,实现视频信号的采集。针对选择的4G通讯模块,编写该模块Linux驱动程序,移植PPP协议程序,使构建的嵌入式设备接入互联网。在以上工作的基础上,移植x264编码器程序,并对采集到视频信号进行编码,将编码后的视频码流按照实时传输协议RTP进行打包。利用内网穿透技术将打包好的视频文件发送到服务器端PC上,通过PC上的VLC播放器显示传输视频信息。针对采用x264码率控制算法ABR控制码率时会出现较大误差的问题,对其源码进行分析,找出码率控制不精确的原因。根据码率控制特点,研究并采用模糊控制方法对码率控制进行优化,在此基础上针对ABR算法设计模糊控制器,并给出优化结果。搭建实验测试平台进行测试,测试结果表明,本系统可以实现嵌入式无线视频传输功能,优化后的ABR算法比优化前更接近目标码率。
[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.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN919.8

【参考文献】