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The future development direction of digital remote surveillance system

2014-06-13

The security system is an intrusion alarm system, a video security monitoring system, an entrance and exit control system, an explosion-proof security inspection system, etc., which are constructed by using security products and other related products for the purpose of maintaining social public safety; or by combining these systems as subsystems to integrate electrinic system or network. According to the <12th Five-Year Development Plan of China's Security Industry>, as of 2010, the total output value of China's security industry reached more than 230 billion yuan, of which the output value of security products is about 100 billion yuan. According to the estimate for the doubling of the industrial scale during the period, the total output value of the security industry in 2015 will reach 500 billion yuan. As an important part of the security system, the video surveillance system has occupied more than half of the domestic security industry market share due to the continuous expansion of its application fields and the continuous expansion of the industry. This article focuses on the evolution of video surveillance.

Four stages of video surveillance development


With the continuous integration of computer multimedia technology, coding compression technology, network transmission technology, storage technology and video surveillance, the development of video surveillance has experienced the evolution of digital remote monitoring system, digital remote monitoring system, network video surveillance, and high-definition video surveillance. The functions, form and composition of video surveillance have undergone tremendous changes.


Digital remote surveillance system phase


The digital remote surveillance system began in the 1970s. At this stage, the analog camera was mainly used for video signal acquisition, and the video signal was transmitted to the matrix host or display and recording device through the coaxial cable. In the digital remote surveillance system, the switching control device based on analog matrix and analog keyboard, while the display and video recording equipment adopts monitor and video cassette recorder (VCR, VideoCassetteRecorder).


Digital remote monitoring system (CTV), also known as Closed Circuit Television (CCTV), consists of analog cameras, video splitters, analog matrix, control keyboard and video tape recorder (VCR), which can realize basic functions like monitoring, video recording and playback. Mainly used coaxial cable (75Ω, 1.0Vp-p) to transmit composite video broadcast signals (CVBS, CompositeVideo BroadcastSignal).


Digital remote surveillance system phase


The digital remote surveillance system began in the late 1990s. At this stage, the analog signal collected by the analog camera was mainly used for analog-to-digital conversion, encoding, and compression by video compression card, and the PC was used for local storage. The DVR at this stage adopts PC-based architecture, which mainly realizes analog signal digitization and video encoding, compression and storage functions. The functions in network transmission, software application, matrix control, etc. are not perfect, so usually work with analog matrix in application.


PC-DigitalVideoRecoder (PC-DVR) was born in the initial stage of the digital remote surveillance system era. It provides a reliable guarantee for the digital remote surveillance system to successfully complete the digitalization of analog signals, and effectively solves the digital remote surveillance system video storage Limitations of media and storage cycles. The digital remote monitoring system is mainly composed of analog cameras, PC-DVR, monitors, etc. It can realize basic functions such as monitoring (monitoring), recording, playback, alarm linkage, voice intercom, real-time control and so on.


In addition to the digital-to-analog conversion, encoding and compression of the front-end analog signals, the PC-DVR can also realize the local storage of compressed data. The signal transmission medium is still a coaxial cable (75Ω, 1.0Vp-p).


Network video surveillance phase


Network video surveillance began around 2005. At the beginning of this phase, the embedded network hard disk recording (E-DVR, Embedded Digital VideoRecoder) or embedded video server (DVS, DigitalVideoServer) was used to digitize, encode, compress and access the network, realized implement networked video surveillance. With the continuous deepening of the construction of safe cities and the continuous expansion of video surveillance in financial and other industries, the demand for video surveillance networking has become increasingly apparent, which has had a positive impact on the development of video surveillance networking. At present, China's video surveillance industry has basically realized network video surveillance.


1. Network video surveillance with analog access mode


In daily applications, if the video resolution requirement is not very high in a small surveillance scenario, an analog solution may be used, that is, an "analog camera + DVR + monitor + PC (client)" architecture. In this kind of architecture, the front end usually adopts the standard definition analog camera to realize the acquisition of the video signal, and transmits it to the DVR through the coaxial cable for encoding and storage, and the DVR can be connected to the monitor for real-time preview and playback operations. In this solution, the DVR connect to the network, and the client can remotely access the DVR for remote operation.


2. Network video monitoring of analog-to-digital hybrid access mode


The signal of the front-end analog camera can be directly transmitted to the surveillance system center, or by placing a video encoding device close to the front-end device, digitizing, encoding, and compressing several analog video signals into packets that can be transmitted over the network (or wireless to surveillance center directly. In the surveillance center, the analog signal is connected to the analog matrix through the video distributor, and the digital signal is converted into an analog video signal to the analog matrix through the video decoding device, and all the video and audio data are stored in the hybrid hard disk recorder (H-DVR).


HD video surveillance stage


After the networked surveillance is satisfied as a basic application, the desire to see the details of the face, license plate and other details has shifted the user's attention to the improvement of video clarity, and HD video surveillance has begun to emerge.


In order to realize high-definition video surveillance in true sense, all aspects of acquisition, transmission, storage, decoding, display and control have strict requirements and are indispensable. China's video surveillance industry is still in the initial stage of high-definition video surveillance, and the trend of high-definition will continue for a long time.


1. HD video surveillance with full IP access


High-definition surveillance of all-IP access mode is one of the most typical application modes. In this architecture, video and audio data is transmitted over IP networks in the form of IP packets.


Front-end: After the video image acquisition by the network HD camera, then encoding compression and transmitted back through the network, in addition, signals such as alarms and sounds can be connected to the camera for back-transmission.


Transmission: Data transmission is connected through the Ethernet layer.


Storage: The video streams are all encoded into digital signals, they can be stored via NVR, NAS or IPSAN.


Display: The front-end video source can be decoded by the decoder to display on wall to completed the operation of rounding and switching control.


Control: The corresponding operation can be completed by the keyboard control decoder or the front-end dome, pan/tilt and other devices.


Management: All devices can be managed by the client and linked with alarms, sounds and other signals.


2. HD video surveillance with full digital access


In general, the high-definition surveillance mode by using all-digital access method is relatively less.


Front-end: The signal transmitted by the camera is uncompressed bare data collected from the image sensor. It has advantages over the network camera in terms of image detail, color reproduction, and control delay, but the cost is high.