【作者】 戴洁；

【导师】 俞立； 孟利民；

【作者基本信息】 浙江工业大学 ， 控制理论与控制工程， 2008， 硕士

【摘要】 近年来,多媒体技术与网络技术的迅速发展,以声音、图形、图像、文本等为主的多媒体通信成为时代的主题,受到人们越来越多的关注。同时,随着高速无线通信的发展,多媒体和无线通信这两个领域技术相互交叉,产生了新的技术——无线多媒体技术。而随着计算机技术逐步步入所谓的“后PC时代”,无线多媒体终端也相应地向小型化,嵌入式方向发展,其强大的功能和广阔的应用前景,使之成为近年来该领域的一个研究热点。本课题来源于浙江省科技厅资助项目“基于DSP技术的全数字实时无线多媒体传输系统的研制”,通过对相关国际标准、关键技术和现有产品的研究和分析,完成系统整体设计方案,并实现了原型系统以进行技术验证。本论文的主要研究内容和成果如下:1.通过比较和研究多种音频、视频编解码标准,提出了适合在资源受限系统中应用的编解码规则,并且利用音视频同步算法和回音消除算法进行优化,使系统更好地满足了音视频传输实时性的需要;2.提出了无线多媒体系统的总体框架,介绍了基于ARM9(S3C2410)处理器为硬件平台,嵌入式Linux操作系统为软件平台,WLAN为传输媒介的平台构架和环境搭建,其中包括软硬件选型,交叉编译环境的建立、Bootloader、Linux内核镜像、文件系统的编译、配置和下载;3.实现了上层应用程序模块化设计,从功能上分为五大模块:音视频采集模块、RTP协议无线传输模块、音视频同步模块、音视频播放/显示模块和回音消除模块,并通过Linux多线程编程技术实现了各个模块的代码化,论文给出了各个模块实现的关键技术和算法流程。最后的实验结果表明,媒体流能在整个系统中得到平稳、实时、同步地处理。本课题所研究的基于嵌入式Linux的无线多媒体系统可广泛应用于视频监控、信息家电、智能小区、远程抄表等领域,具有很强的实用价值,同时也对未来嵌入式系统研究和无线多媒体技术研究起到一定的参考作用。更多还原

【Abstract】 With the progress of the multimedia and networking technology in recent years, multimedia communications have become the theme of this age and being concerned by more and more people. Meanwhile, as the computer technology has gradually gotten onto the so-called "post-PC era", wireless multimedia system is encountering to the corresponding small, embedded development. It will become a hotspot in recent years for its outstanding performance and a broad application prospects in many fields.With the project of "Real-Time Digital Transmission System based on the DSP Application" which is supported by Zhejiang Science& Technology Department, via research to related key point of standards and theories, this thesis complete the design and implementation of the system and analyzes and tests the system performance finally.Firstly, through studying and comparison towards some kinds of audio and video codec, the simplified codec algorithm is introduced to meet the needs of the resource-limited system.Secondly, a total block diagram of a wireless video system is been put forward and the system based on the ARM9 (S3C2410) processor as hardware, the Embedded Linux as software and WLAN as transmission medium is been describes and built on, including how to make choice, cross-compile environment building, Bootloader, Linux kernel, file system compiling, configuring and downloading.Subsequently, the five parts: AV capture block, RTP protocol wireless transmission block, AV synchronization block, AV display block and echo-elimination block are well modularized and their functions are realized by utilizing the multi-thread technology provided by Linux. The thesis gives the key issues and flow chart of every module.Finally, the test result shows the whole system successfully managed the media stream in a smooth, real-time and synchronous way. It can be widely applied on video controlling, information household appliances, intellectual district, remote meter reading etc. and it can provide reference for the future research of Embedded system and wireless multimedia.更多还原