Three technologies of the hottest video surveillan

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As early as august2004, Shanghai planned to install more than 200000 surveillance cameras in the urban area by 2010 to comprehensively build a "social prevention and control system". The social prevention and control system is only one of the applications of video surveillance, but it is enough to illustrate the huge scale of the video surveillance market. After the "9.11" terrorist attacks, the Madrid bombings and the London bombings, people have paid more attention to social security, and video surveillance has extended from the original finance, commerce, transportation, housing and community to all walks of life. This shows that the market of video surveillance has begun to heat up

but the temperature of the early video monitoring service can be said to be the weather in early spring, warm at first and cold at first. This is due to the immaturity of computer, digital codec, network and other technologies at that time, which affected the maturity of video monitoring technology

how the three whirlwinds build momentum step by step

it is the whirlwinds of computer, digital codec and network technologies that have led to the rapid development of video monitoring technology since the 1980s

let's review how these three whirlwinds build momentum step by step

local analog monitoring stage

when black-and-white cameras and black-and-white televisions appear, the early black-and-white image television monitoring system is also born. At that time, most monitoring systems used analog transmission. The simplest way was to send the image baseband information directly to the video transmission cable for transmission. The video information of each monitoring point is directly connected to the multi-channel switching console in the central control room through a cable, and the control point image is selected and displayed on the TV through manual switching

the experiment is simulated by the grinding of one steel ball and three steel balls. The monitoring system has simple function, poor reliability, easy to be disturbed and short system life

PC based multimedia monitoring stage

in the mid-1990s, PC based multimedia monitoring came into being with the development of digital video compression and coding technology. The system has several cameras, various detection and alarm probes and data equipment at the far end to obtain image information, which can be easily identified by using signs or other parties. (2) the zigzag test position of the oil cylinder down type universal testing machine is relatively low, and is connected to the multimedia monitoring terminal through their respective transmission lines, and then these information is transmitted to one or more monitoring centers through the communication network. The monitoring terminal is either a PC or a dedicated industrial control computer

this kind of monitoring system has strong functionality and is convenient for field operation; However, the stability is not good enough, the structure is complex, the video front end (such as CCD video signal acquisition, compression, communication) is complex, and the reliability is not high; High power consumption and cost, requiring multiple personnel on duty; At the same time, the openness of the software is not good, and the transmission distance is obviously limited

remote video monitoring based on Web server

in the late 1990s, with the development of network technology, the embedded web server technology was given remote network video monitoring, and network video monitoring technology came into being

network digital monitoring based on embedded technology 4. The system with spots on the surface of plated parts does not need a PC to process analog video signals, but directly converts the analog video signals output by the camera into IP digital signals through the embedded video encoder

the key equipment of the remote network digital video monitoring system is a video server with embedded web server. It is widely combined with multimedia, image processing, network technology and information technology, so that video monitoring basically meets people's requirements for video monitoring system. The video server is mainly composed of mass storage device, input/output channel, video and audio interface, network interface, rs422/rs232 serial interface, software interface, protocol interface and video and audio matrix. Usually an embedded web server is connected directly to the local area. It is used for compressing video and audio data, storage and other processing. The network video monitoring system based on video server has a wide control area, and the video server is directly connected to the network, plug and play. All devices in the system are identified by IP addresses, and the hardware devices of the video server are tightly bound with the processor and the operating system with unique functions. Therefore, the performance is more stable, which is not only convenient for installation and maintenance, but also conducive to the modular design and management of the system. The video monitoring system based on video server is shown in the figure above

in terms of system construction, the network video monitoring system mainly has the following conditions that should be met: network conditions (mainly the network structure and mode of the system. The existing network forms include LAN, WLAN, ADSL, PSTN, ISDN, xDSL, CDMA, GPRS, satellite communication, etc.). The front-end coding equipment (network video server) is mainly used for audio and video acquisition and coding, which is convenient for network transmission. The monitoring center is mainly the video and audio restoration and integrated management system (center management software)

in terms of the key technologies involved in the system, the key technologies in the video monitoring system mainly include: digital encoding and decoding technology, digital video network transmission protocol and remote digital video monitoring system software. (end)

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