【作者】 杨淼；

【导师】 赵宏伟；

【作者基本信息】 吉林大学 ， 软件工程， 2013， 硕士

【摘要】 随着时代的发展，科技的进步，人们对生活的质量要求日益增加，也更加注重内心的安全感。视频监控系统是人们生产生活中的安全防范措施之一，是保障人民财产生活安全的重要组成部分。视频监控在生活中随处可见，银行的ATM自动取款机、交通监管、超市消费、社区楼宇监控，甚至森林防火、动物习性考察研究等都应用了视频监控技术。视频监控系统在短短三十多年间经历了三个发展时代，广泛地应用在各个领域，与人们的生活息息相关。目前视频监控系统主要向着图像高清化、监控智能化、传输网络化的方向发展。本文的无线视频监控系统属于第三代监控系统，主要由多个采集端、无线传输网络和监控端三部分组成。每个部分负责完成不同的任务，各个部分之间承接转圜、协同工作。本系统选用Samsung S3C2440为处理器的友善之臂mini2440嵌入式开发板作为采集端和监控端，以嵌入式开发技术为核心，结合V4L视频采集技术、FFMPAG视频编解码技术、无线WiFi技术、RTP/RTCP网络传输协议、Qt图形界面开发框架，根据用户调研获取的软件需求设计和实现的。无论是采集端还是监控端，整个系统都继承了嵌入式系统软硬件可裁剪、成本低、可靠性强、性能高、扩展性强等特点，产品小巧灵活、使用方便。由于该系统采用无线传输的方式，用户无需受位置固定的约束，只要在网络范围内，就可随时随地地对目标物进行监控。摆脱了电缆的束缚，免去了额外布线的开销。本系统的视频采集端使用摄像头采集视频图像并经过压缩编码处理后通过无线网卡发送到视频监控端。视频监控端接收传输过来的视频图像并进行解码处理，最终将视频图像显示在设备终端上。视频图像的播放显示可分为多路分屏播放和单路全屏播放两种方式。在视频播放的过程中可进行截屏、画面时间段保存以及回放等操作。视频监控端还设计和实现了一些辅助应用程序，如时钟、记事本等。本文首先介绍了视频监控系统的现状和发展趋势，对相关技术做系统的研究和介绍。通过调研实现了系统需求的获取，并结合实际情况对需求进行了分析。根据需求分析结果确定了系统的功能并进行了模块化的划分，设计了详细的系统软硬件体系结构，实现了视频解码模块、视频播放模块以及部分辅助应用程序，并针对模块性能设计和实践了测试方案。视频图像解码模块主要应用FFMPEG技术，为从采集端传输过来的已经过压缩编码处理的媒体流实现解码处理。其实现过程包括注册解码器、提取媒体流信息、解码器匹配、资源申请与释放、解码媒体流等。同时结合Qt框架通过QProcess类调用已实现的外部解码模块。视频播放模块，通过Qt多线程机制实现了单路全屏和多路分屏两种播放模式，同时实现了截图、时间段保存等监控辅助功能。通过视觉感官、帧频分析和系统运行效率等方式对模块功能进行了测试。本文最后讲述了系统开发环境的搭建和系统的移植过程，并对整个系统做了工作总结和展望。更多还原

【Abstract】 With the development of the times and technology, the requirements of quality of life isincreasing, more attention is paid to the inner security. Video monitoring system is one of thesecurity measures in people’s life and production, and also an important part of protecting thesafety of people’s property and life. Video monitoring system can be seen everywhere in life,such as the bank’s ATM machine, traffic regulatory, supermarket consumption monitoring,community security monitoring, even forest fire prevention and study for animals’ behavior.Video monitoring system has gone through three stages in the past30years. Now videomonitoring system is widely used in various fields and closely related to people’s life. Videomonitoring system is developing mainly towards the direction of high-definition imaging,intelligent monitoring and networked transmission.The wireless video monitoring system belongs to the third generation of videomonitoring system. It is composed mainly by multiple capture terminal, wireless transmissionnetwork and monitoring terminal. When working, each part responsible for different taskscooperates with others. The system selects Friendly-ARM mini2440board with SamsungS3C2440processor as capture and monitoring terminal, embedded development technologyas the core, combining with V4L video capture technology, FFMPAG video codec technology,wireless WiFi technology, RTP/RTCP network transport protocol, Qt graphical interfacedevelopment framework. The system is designed and implemented based on the systemrequirements obtained by user research. Regardless capture or monitoring terminal, the wholesystem inherits the characteristics of embedded system, that is cropped hardware andsoftware, lower cost, higher reliability and performance, stronger scalability. Portability andconvenience is also indispensable. Because of the usage of wireless transmission network,users are not subject to the constraints of fixed working location. As long as the network-wide,users can monitor the target anywhere and anytime, getting rid of the shackles of cable andeliminating the need for additional wiring overhead.In the system, the video capture terminal captures the images by camera and encodes theimages before sending to the video monitor terminal through a wireless card. Videomonitoring terminal receives the images over transmission, decodes the images and finally displays the images on the device terminal. Images can be displayed in two ways, one issingle full-screen play, the other is multiple split-screen play. Users can perform operationssuch as screenshot, period save and playback when video images play. Video monitoringterminal also contains some auxiliary applications, for example, clock and notepad.The paper firstly introduces the status and development trend of video monitoringsystem, and does the research of related technologies as well. Analyze the systemrequirements obtained by the user research by combining with the actual situation. Determinethe function and complete the modular division based on the requirements. Then design thehardware and software system architecture in detail, implement and test video decodingmodule, video display module as well as auxiliary applications.Video decoding module mainly applies FFMPEG techniques, implementing decodingprocess for compressed media stream transmitted from the capture terminal. Theimplementation process includes decoder registration, media stream extraction, decodermatch, resources application and release and media stream decoding. Combined with the Qtframework, call the external implemented decoding module through the QProcess class.Video display module implements single full-screen and multiple split-screen displaymode by Qt multithreaded mechanism, as well as some monitoring auxiliary functions likescreenshots and period preservation. Finally test the module function by visual senses, framerate analysis and system operating efficiency.The paper finally talk about the process of building system development environmentand system migration, summarize the work and outlook the system.更多还原