Analysis of the Solution of Urban Security Network Video Surveillance System

The monitoring system described in this article has built about 2,000 monitoring points based on the needs of urban public security monitoring. The backbone network uses gigabit optical fiber transmission and a two-level management system, which can provide scalable connection interfaces. This solution uses a distributed video service system, which can freely divide the network service structure and build a framework system on the existing network, so that the system can achieve zero wiring or a small amount of wiring, so the expansion is not subject to any structural restrictions and can be expanded infinitely with the extension of the network.

According to current applications and future development needs, the current urban video surveillance system must achieve the following goals:

1. Break the existing situation of multiple command centers coexisting, conduct centralized investment and management, avoid duplicate investment and construction, improve technical maintenance and management level while saving resources, and enable discrete databases and information resources to be linked and shared to play a greater role. Use computer-aided dispatch technology, equip with advanced command and dispatch communication system and information management system, so that the alarm reception and handling can be more accurate and faster, greatly improving the city's response ability to various emergencies.

2. Adopt a unified command and dispatch system to enable cross-departmental, cross-police district, and cross-police types to communicate and collaborate, making unified command and coordinated operations possible, and realizing true social emergency joint action. For example, there are currently multiple public special service numbers (110, 119, 120, etc.), which are difficult for citizens to remember and inconvenient to get corresponding services, assistance and protection. The urban public security monitoring system should allow citizens to call the same number for any alarm or help, and no longer need to remember many special service numbers, and there is no risk of forgetting numbers, saving precious time for obtaining various services and assistance. At the same time, it enables city leaders to quickly obtain information and help to make correct and rapid decisions.

In summary, the urban public security monitoring system should break the digital divide between the existing multiple command centers, enable discrete databases and information resources to be interconnected and shared, and play a greater role.

User needs

Monitoring of key locations such as city entrances and exits, major traffic arteries, intersections, crime-prone areas, financial and commercial areas, and key units; improving the real-time discovery rate and response speed of the city's public security organs to cases. In particular, we must improve the ability to prevent, control, and fight "two robberies and one theft"; improve the city's public security organs' rate of investigation and discovery of cases, and improve the efficiency and effectiveness of evidence collection to increase the rate of solving cases; improve the response speed and processing capabilities to emergency events, as well as the ability to manage plans for specific events; realize a distributed network architecture to form a multi-level management model; realize video information sharing and interconnection and mutual control, support authorized access by relevant units, and improve the comprehensive benefits of the entire urban video alarm monitoring system. Through the comprehensive use of various resources, it can become an auxiliary decision-making tool for major events; through multi-level user authority management and log management, improve the use safety and management efficiency of the monitoring system.

Monitoring system design

Overall design description

According to the requirements of the urban public security monitoring system and combined with the actual situation, a solution as shown in Figure 1 was designed.

The management of the urban public security monitoring system is mainly divided into two levels of management, the second level is the command center, and the first level is the sub-control center. Considering the networking of the entire city in the future, the system must provide a network interface that can connect to the superior department.

Secondary point (command center): plays the role of overall dispatching for the monitoring system of the entire area, and mainly displays images of important locations on the TV wall of the command center. It has the highest management authority of the entire monitoring system, can monitor each node of the system, set the working status of each node, retrieve, query, and playback historical monitoring images, and quickly notify relevant departments to handle accordingly when an alarm occurs. The information center to which the command center belongs is responsible for the management and daily maintenance of the entire system operation. The administrator can remotely upgrade and control the equipment through the network, and can also replace faulty equipment without affecting the normal operation of the system;

Network composition and security requirements

Traffic security video surveillance and traffic management transmission constitute a video transmission network, which is not mixed with the existing public security network. The existing public security networks of various county, city and district bureaus and urban police stations are all upgraded to 100M, and key network equipment is appropriately upgraded.

The monitoring point access of the video transmission network and the network security measures that meet the requirements of the Ministry of Public Security must be deployed between the public security network to ensure the security of the public security network. The city's public security monitoring system is divided into two levels of management systems. The second level is the command center, which has a large screen display wall. All road monitoring and camera images at key locations are aggregated to the command center for control and storage. The first level is the sub-control center. The camera images and information of each area under its jurisdiction first enter the sub-control center of the jurisdiction. All cameras are monitored and stored locally, and key cameras can simultaneously forward signals to the command center for monitoring and storage. The management method of command center and hierarchical monitoring is adopted.

Distribution of monitoring points

In this system, more than 2,000 monitoring points are distributed at intersections of government agencies, intersections and main sections of 1-4 level highways, and important public entertainment venues. Network video encoders are used to encode the relevant video information of each monitoring and monitoring locally and transmit it to the sub-control centers under their jurisdiction. The sub-control centers decode the images through network video decoders and transmit them to the TV wall through analog output for display. At the same time, it is necessary to be able to centrally manage the network video encoders in the area under their jurisdiction and upload them to the command center through the network. On the other hand, any authorized user who can connect to the network can view and control the monitoring video stream through the PC client.

System overall structure

As shown in Figure 2, the analog signal at the monitoring end is converted into a digital signal using an encoder and transmitted to the video management server of each sub-control center through the network. The video management server receives the digital signal and forwards the data to the local and superior command center in unicast mode. The decoders of the local and superior command centers decode the digital signal and transmit it to the output device.

Division Design

Function of sub-control center

The cameras, alarm equipment, and voices at each monitoring point at the front end are connected to the corresponding interfaces of the encoder to complete the digitization of the analog signals at the monitoring points, and the digital signals are then connected to the area under its jurisdiction through the network. The sub-control center is equipped with a first-level video management server, video decoder, monitoring client, network storage device, TV wall, etc. The first-level video management server at the sub-control center forwards the video, audio, and alarm signals of the monitoring point to the second-level video management server at the command center. The system allows the corresponding authorized users to directly access the first-level video management server of the sub-control center or the sub-control center of the same level or the second-level video management server of the command center through the software client, and output images within the scope of authority.

The storage device stores the video and audio of the monitoring points in the jurisdiction locally. The decoder is responsible for decoding the video data forwarded by the video management server and restoring it into analog signals and outputting them to the TV wall, ensuring that each monitoring image in the jurisdiction can be displayed in turn, and multiple monitoring point images can be displayed simultaneously. Each sub-control center mainly monitors the monitoring points in its jurisdiction 24 hours a day in real time, and decodes them on the TV wall through the decoder. If a problem occurs at a monitoring point, the on-duty personnel will promptly notify the on-duty personnel at the location of the incident or handle it personally.

The sub-control center is the most direct combat unit on the front line, and its front-end monitoring points are distributed in the main streets, highways and important public places. The system encodes the relevant video information monitored by each monitoring point locally and transmits it to the sub-control center LAN through optical fiber. The sub-control center accesses the images of their respective areas output by the first-level video management server of the sub-control center through the client. The images are forwarded and uploaded to the command center, realizing the management method combining the command center and the sub-control center (the management structure is shown in Figure 3).

Command Center Function

The center is equipped with secondary video management servers, integrated management server clusters, video decoders, client PCs and other equipment, and uses gigabit optical fiber access. Secondary video management servers, integrated application server clusters (GIS, license plate recognition, etc.), video decoders, network storage devices, TV walls, etc. are placed in the command center's local area network. In addition to managing the cameras connected to the area, the secondary video management server is also responsible for managing the cameras of the subordinate sub-control centers. It remotely controls and manages the cameras and other equipment of each monitoring point at the front end, and forwards the data stream forwarded by the primary video management server of each sub-control center and the data stream received by the encoder in unicast mode; the storage device stores the video transmitted by the front end by installing storage software; the decoder is responsible for decoding the video signal and data of the video forwarding server, and outputs the restored video signal to the TV wall and the voice signal to the speaker, and forwards the images of all monitoring points at the front end in real time in a patrol mode on the TV wall composed of monitors or DLP large screens for direct management personnel to use; management personnel can use PCs located in the network to browse in real time by installing client software and allocating corresponding permissions, and can also control the images of each monitoring point belonging to this center. Clients can be added according to specific circumstances, as long as the PC is connected to the network, and the center does not need to add any equipment.

The command center is the core of the entire system and is the data management and data storage center. The first-level video management server of each sub-control center transfers the sound and uploads the video stream to the command center, forming a complete emergency monitoring system structure and forming a complete system function.

The client PC installs video surveillance server software and database system to manage all front-end cameras, video servers and other equipment, and implements authorization management for users in the network. Users can monitor, query, record, play back and perform other operations on images according to different permissions. 1/4/9/16 images can be displayed at the same time, realizing the database synchronization function of all server software in the entire system and realizing unified data management.

Storage Design

Each sub-control center is equipped with a large-capacity disk array, which is responsible for storing the monitoring points in the area under its jurisdiction. The command center only stores key and alarm monitoring points to save network bandwidth. All video and audio data can be transmitted back to the center. The general video storage time is 7 days, after which the data is automatically replaced. Important and alarm videos are guaranteed to be stored for 15 days, and important data can be burned to a CD for long-term storage for future use.

As shown in Figure 4, the camera completes video digitization through the video server, which is a necessary condition for realizing full digital monitoring.

Monitoring center design requirements

System functions:

·Collection of video images;

Transmission of video images;

Real-time monitoring of major traffic intersections, parks and key locations, and control of corresponding equipment, police force and event handling according to actual conditions;

Realize the processing, storage, control and management of video information;

User and permission management;

Criminal case scene handling and image query;

·Supervise and handle major emergencies;

·Command and dispatch of major social activities;

·Command and dispatch of major security operations;

·Alarm linkage;

Voice function;

Mobile/wireless monitoring;

·Police Geographic Information System (GIS) functions;

License plate recognition and face recognition systems;

Provide intelligent and convenient management and maintenance;

System platform construction

Platform structure description

1. Establish a unified video surveillance management platform, rely on the network as the transmission channel, browse the front-end video signals on the monitoring terminal, control all cameras, matrices, hard disk recorders, video servers and other equipment through a unified interface, and realize all system functions in this requirement.

2. The platform system has an automatic connection function. After the network is interrupted and then restored, all devices under the management platform should be able to automatically connect to the monitoring system and work normally.

3. It adopts the architecture combining traditional desktop C/S mode, uses SQL server 2000 database, and monitors ordinary users in C/S mode; the platform realizes video monitoring and video playback, and various control supports of video monitoring can be used to be integrated with other systems.

4. The design of the platform software adopts a standardized module structure of three layers, namely the presentation layer, application layer and data layer, and must be constructed in accordance with basic network management requirements such as practicality, compatibility, flexibility and reliability.

5. It has strong scalability and can expand the platform's hardware and modules as the front-end access points increase, and has the technical foundation to realize server clusters.

6. It must be compatible with front-end imaging devices, including hard disk recorders, network video servers, digital cameras and other digital imaging devices; it must be able to realize multiple modes of image acquisition, compression, display, alarm linkage, control, remote storage and playback, remote management, etc.; compatible digital imaging devices should include digital imaging devices of mainstream domestic brands.

Platform Hardware

1. The management platform hardware mainly consists of the central system management server, WEB server, alarm server, video forwarding server, storage server, etc. Each server can be combined and used according to the purpose and load.

2. The management server is the management core of the entire platform and is responsible for the centralized configuration and management of user permissions, equipment status, linkage strategies, electronic maps, alarm information, and operation logs of the entire platform.

3. The alarm server is mainly used to collect and receive alarm information provided by system equipment or alarm interfaces, and configure classification, storage, display and linkage operations for users according to relevant "units" and "roles".

4. The video forwarding server can provide unified information acquisition, forwarding and proxy services for all hard disk recorders, and provide file index information. When users remotely monitor, play back images or query alarm signals, the video forwarding server should send the requested index information to the user.

5. The storage management server mainly realizes the centralized management function of digital video streams and provides relevant video index information for the video forwarding server. The objects managed by the storage management server can be PC server storage devices, DVR devices, disk arrays or tape libraries (the platform modular processing is shown in Figure 5).

Conclusion

From what is described in the above article, the system can realize real-time monitoring, video query, alarm linkage, electronic map, user/equipment management, system maintenance and other functions in the actual application environment, which can well meet the needs of users. After actual application, the system always runs stably.