Video surveillance is the most important part in the security field, including front-end camera, transmission cable and video surveillance platform. A perfect video monitoring system has five parts: camera, transmission, control, display and storage. Relatively speaking, the video surveillance system has strong prevention ability. It is widely used in many occasions because of its intuitive picture, accurate content, timely data and complete information.

Composition of video monitoring system
At present, the whole video surveillance market in China is transitioning from analog to digital, high-definition, networked and intelligent. Digital video surveillance system will replace the analog surveillance system at the end of last century and become the mainstream of the times.

(1) Digitization
The security video surveillance system must digitize the analog signal in order to move towards the development of networking, high-definition and intelligent goal. Networking is the networking of digital video surveillance system, that is, the digital video surveillance system transmitted by network. After the system is networked, its front-end equipment is less than hundreds of thousands, more than tens of thousands or even hundreds of thousands. It is impossible to rely on human monitoring alone. It must be handed over to the computer to analyze, classify, process, identify, track and pre / alarm the image resources of the front-end equipment. This is intelligence, so intelligence is the advanced stage of the development of networking, It is also the necessity of network development. Therefore, the security monitoring system must be networked, high-definition and intelligent on the basis of digitization. Digitization is the foundation and core of developing security video surveillance system.
The remarkable advantages of video digitization include: strong anti-interference ability and greatly improve signal quality. Due to the digital form, it is easy to carry out various digital processing, eliminate noise, separate color and brightness, eliminate brightness flicker and ghosting, reduce nonlinear influence and greatly improve power / frequency utilization; Digital signals are easy to store, copy and provide new functions. Digital TV signals are easy to store, and the repeated reproduction of digital signals will not reduce the quality too much. There are too many new functions: stunts, multi picture, fast retrieval, scaling, random access, editing and so on.

(2) High definition
With the popularization and application of video surveillance, it has become an effective tool to maintain social security and assist public security organs in detecting various illegal cases. However, the effect of video surveillance is not satisfactory in many cases. For example, the major media often see the surveillance video "blind eye", "hide and seek" in a certain area, which often doesn't work at the most critical moment. The "suicide incident of Wu Xiaoqing, a triad related official", which was noisy on the Internet before, but the video surveillance did not catch this picture, which is very embarrassing for the whole video surveillance industry. Everyone should have a similar impression that the surveillance videos or screenshots of the crime scene broadcast in the newspaper or on TV are always as vague as UFO photos. More importantly, it is impossible for the public security organ to solve the case in the shortest time, which requires a lot of human and material resources to restore the image.

Although many HD monitoring products have already appeared in the market, including analog HD (960i), digital HD (HD-SDI) and IP HD, HD has not been widely applied to the video monitoring industry due to the limitations of many factors such as cost and technology. Due to different application environments and purposes, all kinds of HD have a certain development space.

Of course, with the advent of a batch of high-definition products, this phenomenon has decreased, but it still puts forward higher requirements for high-definition video surveillance. For example, with the opening of Wuhan Guangzhou high-speed railway, video monitoring system needs to be installed along the line for all-weather monitoring. For high-speed trains with a speed of up to 350 kilometers per hour, the surrounding safety along the railway is particularly important. Obviously, ordinary cameras are difficult to meet the requirements, and high-definition lenses must be used to ensure the monitoring effect. According to Zhang Shuguang, deputy chief engineer of the Ministry of Railways and deputy chief designer of Passenger Dedicated Lines (high-speed railways), according to China's recent high-speed railway planning, by 2012, China will build 42 passenger dedicated lines with a total mileage of 13000 kilometers, including 5000 kilometers of lines with a speed of 250 kilometers per hour and 8000 kilometers of lines with a speed of 350 kilometers per hour. This is a good opportunity for the development of HD monitoring.

With the rapid development of video surveillance technology, the requirements of users for video surveillance products are also increasing, the functional requirements are more perfect and stable, and the performance requirements are more clear and accurate. At the same time, how to see a person's facial features in shopping malls, banks and other monitoring places? How to see the license plate of a high-speed vehicle clearly? How can we find the target quickly and accurately in crowded and noisy railway stations, stadiums, squares and other occasions? All these problems need high-definition video surveillance products to solve.

(3) Networking
With the increasing emergence of digital and IP technology advantages, the networked development of video surveillance has a solid foundation. For example, due to the use of TCP / IP network, network video monitoring can realize remote monitoring and expand the monitoring range at low cost. These advantages of network video surveillance greatly expand its application scenarios. The use of network video surveillance in some large-scale monitoring projects shows that this technology is beginning to mature. Taking the opportunity of Beijing Olympic Games and Shanghai World Expo, network video surveillance has developed rapidly in recent years.

In fact, the market of network video surveillance is far from only large enterprises and public security. In recent years, with the strengthening and popularization of security awareness, the security field has gradually expanded from public security and monitoring of large and medium-sized enterprises to security prevention and control of small and medium-sized enterprises and family users. With the increase of high-value and large property such as real estate, cars and household appliances, and the emergence of network cameras, the monitoring objects are further expanded, including real-time tracking and monitoring of property, facilities and people. More and more enterprises and families hope to help them avoid losses and accidents as much as possible through the network monitoring system, control the scene at any time, and reduce unsafe, unfair and other factors. In addition, road traffic, enterprise it, education, medical treatment and other aspects also have a huge demand for network video surveillance, and the market development prospect is very promising.

At present, the help of networked digital technology to video surveillance is more an improvement to the transmission environment and capability. In a larger sense, it is the establishment of a new monitoring and management platform. However, if we want to rely on the improvement of network and digital work ability, I'm afraid it's still difficult with the current technology application degree and use environment. Although the current public network environment has been greatly improved, and the types of networks are becoming richer in development. However, the existing public network environment is still difficult to support the huge information flow transmission. Therefore, opening a dedicated network transmission line is the main mode to maintain remote network transmission. Of course, this undoubtedly increases the maintenance cost of the whole system. Users should choose technology according to their actual needs.

(4) Intellectualization
The emergence of intelligent video surveillance technology changes video surveillance from "passive surveillance" to "active surveillance", which frees video surveillance personnel from cumbersome operation and massive information, and helps them manage surveillance targets more efficiently and accurately. And intelligence is the highest state of the "four modernizations".

When it comes to intelligent video surveillance technology, I have to say "Nanjing 1.6 shooting". Two days after the incident, the police released two videos of the robbery. It is understood that it is not easy to obtain these two videos. This achievement was achieved by more than 500 police who screened tens of thousands of hours of video images one by one in 24 hours. It has a large workload and requires more manpower. Time is the key in the process of solving the case. It may be very important to find the line one minute faster for the rapid detection of the case. From these aspects, efficient and intelligent video analysis and retrieval software is undoubtedly very necessary and urgent for modern case solving work.

Although the current market application status of intelligent video surveillance technology is not optimistic, with the development of economy and the increasing demand for video surveillance, the unique advantages of intelligent video will undoubtedly become a new upstart in the demand market of video surveillance system in the future.