Video surveillance system is safe guard system is an important part of a preventive ability strong comprehensive system. Video monitoring with its convenient, intuitive and information content rich and widely used in many occasions. In recent years, with the development of modern science and technology, in particular network bandwidth, computer processing power and storage capacity rapidly increase and various practical video information processing technology, video surveillance technology also appeared a considerable development, video monitoring entered the digital network age, increasingly attention by people and attention. The development of video surveillance system is mainly early analog closed-circuit television monitoring system combined to video monitoring system model of digital video monitor and now the evolution process, and the system of digital video monitor system now according to the technical development and divided into three stages: digital monitor multimedia stage, digital monitor DVR stage and digital monitor network stage.
1, video monitoring system simulations simulate video monitoring system is divided into microprocessor-based video switch control plus PC multimedia management and pc-based realize the switch control of matrix host and system multimedia management two types. Analog closed-circuit television monitoring system is actually the combination of many simulation monitoring equipment, system mainly consists of \"front-end device\" and \"terminal control device\" and \"signal transmission medium\" three parts, including: front-end equipment is mainly a camera, haeundae, decoder, control equipment is mainly a switching matrix, image segmentation device, monitor and control the keyboard, video, etc. Transmission medium including cable, control, etc. As microprocessors, the function, performance of microcomputers and heighten, multimedia technology application, the system in functionality, performance, reliability, structure pattern, etc, great changes have happened to the video monitoring system, more convenient, the composition of the interface with other technical system tends to regulate, man-machine interface more friendly. But because video monitor and control system in the flow of information form does not change, the video signal is still simulation system, the network structure is mainly a ChanGongNeng, one-way, lumped way of information collection network, so system although has developed
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to a high level, has not much potential can dig, its limitations still exist, to meet the higher request, digital is the only way. Simulation monitoring system of main faults are: a, usually only suitable for small range of regional monitor video signal transmission, simulation tools, and is mainly coaxial cable to transmit analog video signal coaxial cable, the distance is not more than the distance twisted-pair dump more short, this determines the analog monitor only suitable for single building, small neighborhood and other small range of places. B, the system of expansion ability difference for has already built good system, if want to add new monitory point, often is one change makes all change, new equipment is also hard to add to the original system in. C, unable to form effective alarm linkage, because each part between independent operation, the control protocol is difficult to each other, linkage in the limited scope only.
2 video monitoring system, digital multimedia technology, video with compression technology, network communication technology of digital video surveillance system development, the rapid rise, on the market today there are two types of digital video monitor system type, one is the digital video equipment video monitoring system for the core, another kind is embedded video Web server video monitoring system for the core.
Digital video compression technology matures, the computer based on PC universalization, create conditions multimedia monitor. This new video monitoring system of rapid rise, partially replaced with video matrix image segmentation device, video as the core, complementary with other transmitter simulation video monitor mode, its advantage mainly displays in: a, PC multimedia monitor video matrix, the host integrated image segmentation device, many functions of video recorders, simplifies the structure of the system. B, because use the computer network technology, digital multimedia remote network monitor from distance limit. C, due to the large capacity disk array inventory device or CD storage, can save you a lot of tape medium, and it is helpful to the multimedia information system.
But as the PC video surveillance video system development, in actual engineering in use process, also exposed some shortage, mainly system work instability. The video surveillance video based on PC for: the structure of system compatible/industrial PC + video capture card + ordinary/more reliable operation platform + application software. From the system composition structure to analysis:
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a, PC for 24 hour uninterrupted job, its performance is not very stable, g-kong PC relative compatible PC's stability have a class enhancement, suitable for complex working environment. B, operating system: with Windows 98 for operation platform system, the industry insiders know, there are certain Win98 stability problem, if at the same time the application software is not very standardized, it'll be easier in use process appears work instability, freezes and other issues, and PC video surveillance video system realization of their software in Windows 95/98 / NT, Unix, Linux operating system, such as general while system files, application software and image files are stored in the disk, video processing must high-density input of large quantities of data, and to work hard drive, the average for the hard disk logic (such as Windows, already can't adapt to FAT32) so susceptible, causing instability crashed phenomenon. C, application software: the simple application software system is not can be used for security video monitoring system, fields of application software ability should support multitasking concurrent processing, such as monitoring, video, playback, backup, alarm, control, remote connection, etc. The ability to deal with more work D, video capture card: video surveillance video system for road input system are usually video capture card, can use multiple CARDS way, also can use single card mode. Say commonly, a single card way better integration high stability will more than all the way, many using card has a card way very easy to form hardware conflicts, its stability will have a major influence. Embedded system is used as the center, software and hardware can be cut, to adapt application system function, reliability and cost, volume etc comprehensive demanding special computer system for monitoring system, i.e. the special computer system tailored.
Embedded system mainly consists of embedded processor, relevant support hardware, embedded operating system and application software system etc, it is the collection software and hardware in the integration of can work independently \"devices\". Embedded operating system is a kind of real-time, supports embedded system application operating system software, it is embedded system extremely important constituent, usually includes and hardware related software drivers, system kernel bottom, device driver interface, communication protocol, graphic interface, standardization browsers, embedded real-time operating system in the related hardware and efficiency of dependence, software application and specificity solid state has more prominent characteristics. The advantages and
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disadvantages of embedded system, the system for a special system, so the system is small, instruction downsizing and processing speed. B, system data in ROM/FLASH with fast speed, call, not be altered, good stability. C, system treatment of good real-time performance, stable performance. D, document management system is more suitable for large amounts of video data. E, in network function, audio and video sync issues may also difficult satisfactory.
Embedded video Web server mode, a built-in video server embedded Web server, the embedded real-time multitasking operating system. The video signal digital camera sent by high compression chip after through internal bus to compress, built-in Web server, Internet users can use directly on the Web server browsers on camera images, subscribers can also control the camera lens, haeundae, the actions or operate on system configuration.
Because the video compression and Web function centralism to a small size within the equipment can be directly connected lans, achieve namely that look, omited inserted range of complex cable, convenient installation (only set an IP address), the user does not need to install any hardware device, with the browser can only watch. Embedded video Web server monitoring system and other surveillance system has the following characteristics: a comparison of embedded video area is vast, have been supervised Web server monitoring system of Web server directly connected network, no cable length and attenuation, and the limit of the concept of network is no distance, completely abandoned regional concept, expand have been supervised areas. B, the system has almost unlimited seamless expansion ability all equipment is mark, with IP address increased equipment just means that IP address the expansion. C, can form a very complicated monitoring network based on embedded Web server is the core of the monitoring system in network mode, with traditional analog monitor and based on PC platforms screening method has greatly different, because Web server output has completed analog to digital conversion and compression, adopt uniform agreement on the network transmission, support across the router across the gateway, remote video transmission. D, stable and reliable performance, without staff management embedded Web server based on embedded computer technology, actually using embedded real-time multitasking operating system, and video compression and Web function due to focus on a small size, within the device directly concatenation LAN or wan, namely that look, system insert real-time, stability, reliability greatly
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improved, also need not specially assigned management, which is very suitable for unattended conditions. E, when the monitoring center needs to watch a video camera image, more network bandwidth will have certain requirements. The development of video monitoring system 1, video monitoring system development direction
Video digitizing, front integration, network, system integration is monitoring the development of video monitoring system, and recognized the direction is the premise of digital network, network and system integration of video monitor based, so, the biggest two characteristics is the digital and network. 2, digital
Digital is the 21st century features, is the information technology as the core, the necessity of the development of electronic technology, digital is toward growth pass, along with the time development, our environment will become more and more digital.
Video surveillance system is the system of digital first should flow in video, audio, (including from analog state control, etc.) state, which to digital completely break \"classic cable TV system based on camera imaging technology as the center\" structure, fundamentally changing video monitoring system from information acquisition, data processing, transmission and system control of the mode and structural form. The flow of information digitization, coding compression, open video monitoring system, make agreements with the security system in other between each subsystem realize seamless connection, and the unified operation platform to realize the management and control system integration, this also is the meaning. 3 and network
Video monitoring system of the structure of the network will mean system by lumped type to distribution type system transition. Distribution type system USES the multi-layer hierarchical structure form and the real-time kernel technology with micro multitask, multi-user, distributed operating system to achieve beat task scheduling algorithm fast response. Distributing type monitoring system of the hardware and software using the standardization, the modularization and the serialization of design, system equipment configuration has the versatility, openness, system configuration flexible, control the perfect function, data processing convenient, friendly man-machine interface and system installation,
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commissioning and maintenance simplify the operation of the system, are hot backup, fault-tolerant reliable, etc. System in some degree of networked broke on regional and equipment have been supervised extended geographical and quantity limits. System network will make the whole network system hardware and software resources sharing and mission and load of sharing, this also is an important concept of the system integration. From the above can see video technology, the development of video, roughly experienced analog video, network video PC in three phases, and depending on the technology of the network, communication and transmission platform.
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外文翻译
视频监控系统是安全防范系统的重要组成部分，是一种防范能力较强的综合系统。视频监控以其直观、方便、信息内容丰富而广泛应用于许多场合。近年来，随着现代科学技术的不断发展特别是网络带宽、计算机处理能力和存储容量的迅速提高以及各种实用视频信息处理技术的出现，视频监控技术也有长足的发展，视频监控进入了全数字化的网络时代，日益受到人们的重视和关注。视频监控系统的发展基本上是从早期的模拟闭路电视监控系统向数模结合的视频监控系统和现在的数字视频监控系统演变的过程，而现在的数字视频监控系统根据技术的发展又分为三个阶段：数字监控的多媒体阶段、数字监控的DVR阶段和数字监控的网络阶段。
1、模拟视频监控系统模拟视频监控系统分为基于微处理器的视频切换控制加PC机的多媒体管理和基于PC机实现对矩阵主机的切换控制及对系统的多媒体管理两种类型。模拟闭路电视监控系统实际上就是许多模拟监控设备的组合，系统主要由“前端设备”和“终端控制设备”以及“信号传输介质”三个部分组成，其中：前端设备主要有摄像机、云台、解码器等，控制设备主要有切换矩阵、画面分割器、监视器、控制键盘、录像机等。传输介质包括电缆、控制线等。随着微处理器、微机的功能、性能的增强和提高，多媒体技术的应用，系统在功能、性能、可靠性、结构方式等方面都发生了很大的变化，视频监控系统的构成更加方便灵活、与其它技术系统的接口趋于规范，人机交互界面更为友好。但由于视频监控系统中信息流的形态没有变，仍为模拟的视频信号，系统的网络结构主要是一种单功能、单向、集总方式的信息采集网络，因此系统尽管已发展到很高的水平，已无太多潜力可挖，其局限性依然存在，要满足更高的要求，数字化是必由之路。模拟监控系统的主要缺点有：a、通常只适合于小范围的区域监控，模拟视频信号的传输工具主要是同轴电缆，而同轴电缆传输模拟视频信号的距离不大于1Km，双绞线的距离更短，这就决定了模拟监控只适合于单个大楼、小的居民区以及其它小范围的场所。b、系统的扩展能力差对于已经建好的系统，如要增加新的监控点，往往是牵一发而动全身，新的设备也很难添加到原有的系统之中。c、无法形成有效的报警联动，由于各部分独立运作，相互之间的控制协议很难互通，联动只能在有限的范围内进行。
2、数字视频监控系统随着多媒体技术、视频压缩编码技术、网络通讯技术的发展、数字视频监控系统迅速崛起，现今市场上有两种数字视频监控系统类型，一种是以数字录像设备为核心的视频监控系统，另一种是以嵌入式视频Web服务器为核心的视频监控系统。
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数字视频压缩编码技术日益成熟，计算机的普及化，为基于PC机的多媒体监控创造了条件。这种新型视频监控系统的迅速崛起，部分地取代了以视频矩阵图像分割器、录像机为核心，辅以其它传送器的模拟视频监控模式，其优越性主要表现在：a、PC机的多媒体监控主机综合了视频矩阵、图像分割器、录像机等的众多功能，使系统结构大为简化。b、由于采用计算机网络技术，数字多媒体远程网络监控不受距离限制。c、由于采用大容量磁盘阵列存盘器或光盘存储器，可以节省大量的磁带介质，同时有利于系统实现多媒体信息查询。
但随着基于PC机的视频监控录像系统的发展，在实际工程使用过程中，也暴露出一些不足，主要是系统工作的不稳定性。基于PC的视频监控录像系统的组成结构为：兼容/工控PC机+视频采集卡+普通/较可靠的操作平台+应用软件。从系统的组成结构来分析：a、PC机用于24小时不间断工作时，其性能是不很稳定的，工控PC机相对兼容PC机的稳定性有一个档次上的提高，适用于较复杂的工作环境。b、操作系统：以Windows 98为操作平台的系统，业内人士都知道，Win98的稳定性是有一定问题的，如果同时应用软件又不是很规范，这样就容易在使用过程中出现工作不稳定、死机等问题，而基于PC机的视频监控录像系统其软件的实现是在Windows 95/98/NT、Unix、Linux等通用操作系统上，同时系统文件、应用软件和图像文件都存储在硬盘上，视频处理必须高密度输入大量数据，同时硬盘要进行多工工作，普通的硬盘逻辑（如Windows的FAT32）已无法适应，以致极易产生系统的不稳定性，造成死机现象。c 、应用软件：采用简易应用软件的系统是不能够用于安防领域的，视频监控系统的应用软件能力上应支持多任务并发处理，如监视、录像、回放、备份、报警、控制、远程连接等的多工处理能力。d、视频采集卡：视频监控录像系统通常均为多路输入系统，视频采集卡可采用多卡方式，也可采用单卡方式。一般说，单卡方式集成度高，稳定性会优于多卡方式，很多采用一路一卡的方式很容易形成硬件冲突，其稳定性会有较大的影响。嵌入式系统是以应用为中心，软硬件可裁减的，适应应用系统对功能、可靠性、成本、体积等综合性严格要求的专用计算机系统，亦即为监控系统量体裁衣的专用计算机系统。
嵌入式系统主要由嵌入式处理器、相关支撑硬件、嵌入式操作系统及应用软件系统等组成，它是集软硬件于一体的可独立工作的\"器件\"。嵌入式操作系统是一种实时的，支持嵌入式系统应用的操作系统软件，它是嵌入式系统极为重要的组成部分，通常包括与硬件相关的底层驱动软件、系统内核、设备驱动接口、通信协议、图形界面、标准化浏览器等，嵌入式操作系统在系统实时高效性、硬件的相关依靠性、软件固态化及应用的专用性等方面具有较为突出的
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特点。嵌入式系统的优缺点：a、系统为专用系统，所以系统小，指令精简，处理速度快。b、系统数据置于ROM/FLASH MEMORY，调用速度快，不会被改变，稳定性好。c、系统处理实时性好，性能稳定。d、文件管理系统更适合于大量的视频数据。e、在网络功能、音视频同步等方面也难令人满意。
嵌入式视频Web服务器方式，视频服务器内置一个嵌入式Web服务器，采用嵌入式实时多任务操作系统。摄像机送来的视频信号数字化后由高效压缩芯片压缩，通过内部总线送到内置的Web服务器，网络上用户可以直接用浏览器观看Web服务器上的摄像机图像，授权用户还可以控制摄像机、云台、镜头的动作或对系统配置进行操作。
由于把视频压缩和Web功能集中到一个体积很小的设备内，可以直接连入局域网，达到即插即看，省掉多种复杂的电缆，安装方便（仅需设置一个IP地址），用户也无需安装任何硬件设备，仅用浏览器即可观看。嵌入式视频Web服务器监控系统与其它监控系统的比较有如下特点：a、布控区域广阔嵌入式视频Web服务器监控系统的Web服务器直接连入网络，没有线缆长度和信号衰减的限制，同时网络是没有距离概念的，彻底抛弃了地域的概念，扩展布控区域。b、系统具有几乎无限的无缝扩展能力所有设备都以IP地址进行标识，增加设备只是意味着IP地址的扩充。c、可组成非常复杂的监控网络采用基于嵌入式Web服务器为核心的监控系统，在组网方式上与传统的模拟监控和基于PC平台的监控方式有极大的不同，由于Web服务器输出已完成模拟到数字的转换并压缩，采用统一的协议在网络上传输，支持跨网关、跨路由器的远程视频传输。d、性能稳定可靠，无需专人管理嵌入式Web服务器实际上基于嵌入式电脑技术，采用嵌入式实时多任务操作系统，又由于视频压缩和Web功能集中到一个体积很小的设备内，直接连入局域网或广域网，即插即看，系统的实时性、稳定性、可靠性大大提高，也无需专人管理，非常适合于无人值守的环境。e、当监控中心需要同时观看较多个摄像机图像时，对网络带宽就会有一定的要求。
视频监控系统的发展 1、视频监控系统的发展方向
前端一体化、视频数字化、监控网络化、系统集成化是视频监控系统公认的发展方向，而数字化是网络化的前提，网络化又是系统集成化的基础，所以，视频监控发展的最大两个特点就是数字化和网络化。
2、数字化
数字化是21世纪的特征，是以信息技术为核心的电子技术发展的必然，数字化是迈向成长的通行证，随着时代的发展，我们的生存环境将变得越来越数字化。
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视频监控系统的数字化首先应该是系统中信息流（包括视频、音频、控制等）从模拟状态转为数字状态，这将彻底打破\"经典闭路电视系统是以摄像机成像技术为中心\"的结构，根本上改变视频监控系统从信息采集、数据处理、传输、系统控制等的方式和结构形式。信息流的数字化、编码压缩、开放式的协议，使视频监控系统与安防系统中其它各子系统间实现无缝连接，并在统一的操作平台上实现管理和控制，这也是系统集成化的含义。
3、网络化
视频监控系统的网络化将意味着系统的结构将由集总式向集散式系统过渡。集散式系统采用多层分级的结构形式，具有微内核技术的实时多任务、多用户、分布式操作系统以实现抢先任务调度算法的快速响应。组成集散式监控系统的硬件和软件采用标准化、模块化和系列化的设计，系统设备的配置具有通用性强、开放性好、系统组态灵活、控制功能完善、数据处理方便、人机界面友好以及系统安装、调试和维修简单化，系统运行互为热备份，容错可靠等优点。系统的网络化在某种程度上打破了布控区域和设备扩展的地域和数量界限。系统网络化将使整个网络系统硬件和软件资源的共享以及任务和负载的共享，这也是系统集成的一个重要概念。从以上可以看出，视频技术的发展大致经历了模拟视频、PC视频、网络视频三个阶段，并以网络、通信技术为依托和传输平台。
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