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With the popularization of broadband networks and the increasing demand for management in the industry management departments, the requirements of urban public security, transportation, finance, environmental protection, electric power, medical care, education and other management departments for large-scale network security and video surveillance platforms within the city are also In the past two years, there has been a large increase, especially in the urban public security and financial fields.
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In the urban public security field, the public security department is vigorously carrying out the construction of a demonstration city for science and technology strong police. The first batch of urban security monitoring systems in 22 cities has been implemented. In 2008, the number of demonstration cities for science and technology police will reach 180, and finally 660 in China. Both the city and 1642 counties require a network-based public safety and image surveillance system.
In the financial sector, in the past few years, major domestic banks and commercial banks have built a number of digital monitoring systems for grassroots outlets in accordance with the requirements of the People’s Bank of China and the Ministry of Public Security on the digital reconstruction of bank image monitoring systems. The transformation work has also begun the pilot work of transformation of various networked monitoring and management systems.
With the maturity of network transmission technology and image coding and decoding technology, major breakthroughs have been made in realizing the needs of these emerging industry customers. Large-scale video surveillance systems are rapidly being built across the country.
First, the characteristics of large-scale monitoring system
With the construction of urban security systems and industry security systems, we can see that these large-scale monitoring systems have some common features:
1. Take the platform as the core and use the network as the link
The size and planning of our current security systems has been a bit daunting or awkward for users. How to monitor the images collected by a large number of cameras? How to manage a large number of codec devices? How to manage and manage a large number of back-end servers? By manpower, it is impossible to solve the management problems of large-scale monitoring systems, so create a management The demand for the platform is very urgent. A good management platform can manage all the cameras, manage all the alarm points, manage all the codec devices, and manage all the back-end servers, so that the whole system can run smoothly.
The premise of managing the entire monitoring system with the platform as the core is to have a network with sufficient bandwidth (or enough bandwidth to meet the requirements after management) to connect these devices and servers. No network is empty talk.
2. Access multiple different devices for interoperability
Due to the historical status of the security industry (independent small-scale applications), there are many manufacturers of equipment, and each manufacturer has its own set of codec and network transmission practices. This status quo is very unfavorable for composing large networks. But because of this status quo, we require our large-scale monitoring system platform to access devices from multiple vendors. One protects the user's original investment; the two provide solutions to reduce the user's investment in the construction of the new system.
It seems that the large-scale monitoring systems that have been built and under construction have made a lot of efforts in this respect. They have access to the video codec devices of domestic mainstream manufacturers, and have basically realized the device manufacturers and models on the user side. Transparent.
3. The combination of security and business applications is getting closer
As a specialized business of security (defense) systems, security systems have always maintained a certain distance from other applications in the industry. However, with the deepening of network monitoring, with the refinement of the management level, more and more requirements show that the security system needs to be more closely integrated with other business applications of the industry. Here are some simple examples: Internet cafe monitoring.
Internet cafes have typical industry characteristics. At the business level, operators of Internet cafes pay attention to the operation status of Internet cafes, while public security departments and business administrations pay attention to whether Internet cafes operate illegally. Therefore, for the video surveillance of Internet cafes, the requirements of these two aspects are different. From a regulatory point of view, the general security monitoring system should be able to meet certain requirements, and from the operator's point of view, the ordinary security monitoring system obviously can not meet his needs (and will increase his input). Therefore, how to integrate the security system with the business system of the Internet cafe, reduce the investment, increase the application efficiency, is our security system needs to be considered, and only solve such problems, our security system is everyone's welcome. Thereby helping customers succeed.
Second, the technical points of the large-scale monitoring system
In response to these characteristics, we can analyze the technical points of a large video surveillance system:
1. The platform itself
1.1. Centralized management
Centralized management is embodied in a system that is managed by a central management control server. Any configuration changes of the system and the joining of new units are uniformly authenticated, distributed, and scheduled by the central management server to ensure system consistency and availability. Security and access to timely and consistent information and instructions for each unit in the access system. The other servers in the system are uniformly distributed by the central management server. When the server changes, the central management server performs load transfer in time to achieve reasonable distribution and balance of system resources. Centralized management is also reflected in the fact that system administrators can manage all the devices in the system at their own desks, while also managing the servers and client units in the system without standing in front of any managed objects. Centralized management makes the system simple in architecture, reliable in system, easy to access by client units, easy to authenticate and manage rights. For requests with control contention, a unified policy can be adopted to ensure the consistency of information.
Centralized management is also reflected in a management system of a multi-level management of an organization. The center establishes a master control center domain, has a central control server, and the subordinate establishes a sub-center domain. There is a sub-center control server and instructions of the upper-level center. It can be delivered to the lower-level center. The information and requests of the lower-level center can also be submitted to the higher-level center for centralized distribution, and the users can be managed according to the unified organization to realize the management of multiple sub-regions. The system arbitrates and grants the interconnection of the two domains.
1.2. Distributed services
Since a server cannot afford excessive device access, to ensure a large number of concurrent access, a multi-server form can be used for distributed services, and different access types are also processed by the server. Multiple application servers exist in a domain, allowing the application server to be dynamically increased or decreased, and becomes available when the corresponding server is connected to the central control server. The central control server coordinates the load between servers (DVR access allocation) according to certain policies. The system allows for dynamic increase or decrease of the server. If a server is disconnected, its load is automatically assigned to other active servers.
When the central control server fails, the application server keeps working. After the fault is removed, when the application server connects to the control server, it reports to the control server about the current status of the DVR device and the access status of the client.
When the client requests access to the system, it will get the connection information of the central control server, automatically connect to the management server of the device to be accessed, and submit the access request to be made.
1.3. Hierarchical storage
It consists of multi-domain storage and front-end storage. Each domain manages its own devices. There are multiple storage servers in one domain, which balances the load of the devices and stores the data resources under a unified path. Here, a unified directory access protocol is adopted. Therefore, different storage servers have the same path when accessing the same resource, thereby achieving the purpose of central storage. Secondly, the local storage is also provided on the front-end device, and the video is stored locally, mainly for the purpose of continuous storage of the broken network, and different strategies can be used to store necessary and long-term data in the center, and on the front-end device. Store short-term, comprehensive video data.
1.4. Media Data Forwarding
Because video surveillance has a lot of repetitiveness, for the client's access, the system uses the forwarding server-based transmission method for real-time video distribution, and through multiple network cards, the isolation device and the client network segment, and the device network segment adopts secure TCP. Connections, which avoid conflicts between the two types of network segments, ensure the integrity of the data source, and increase the actual bandwidth of the server network.
The historical video viewing on the DVR is to transfer the video data to the user's request through the streaming media on-demand server, and the system transmits based on the TCP to ensure the integrity of the video data. For a large number of video viewing requests, the server also performs a cache storage and hit strategy. The request to view the same video greatly reduces the repeated requests to the DVR, and also ensures the timeliness of the data obtained by the client.
1.5. System scalability
The distributed service of the system is adopted, and the processing of adding and reducing dynamic services is realized, and the dynamic extension of the system is realized;
Secondly, different types of service separation and service registration/deregistration mechanisms are adopted to enable the system to achieve dynamic scalability.
2. Equipment access
2.1. Unified Access Protocol
In order to connect devices from different manufacturers to a large-scale monitoring system, devices must communicate in accordance with the system's device access protocol. Only when all devices in the entire system speak the same language, the entire system can be interconnected. The purpose of interoperability.
Therefore, defining a universal, scalable device access protocol is an important technical task for large-scale monitoring systems.
2.2. Provide video development kit
Our unified communication protocol does not mean that all the interconnection problems of the system are solved. For various reasons, there are many differences in the encoding formats of audio and video data of various manufacturers, and each manufacturer is required to follow the uniform coding. The format and uniform data encapsulation format to output audio and video data is obviously too demanding. Therefore, it is better to decode the data encoded by the equipment of different manufacturers by using the decoding library (decoding device) provided by the manufacturer.
Therefore, if the device is to be connected to a large monitoring system, the device manufacturer needs to provide a video development kit.
3. Middleware technology
The industry has a wide variety of features, and customer requirements vary widely. Integrating security systems into other business applications will be a trend in the future. Therefore, the management platform on which our large-scale monitoring system is based needs to be a very open platform that can provide various development interfaces: input, output, intermediate control, and so on. ,
Therefore, building the basic platform of the security system into a middleware platform is a better solution.
Provide centralized management, device access, media forwarding, centralized storage, electronic map services, alarm access, etc. on this middleware platform.
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