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With the continuous popularization of 3G networks, in the 3G network environment, the network bandwidth has doubled, which can meet the needs of video data transmission with high frame rate and higher image quality. The original bicycle video-based on-board video surveillance solutions are gradually developing in the direction of systemization, networking, and platformization. Due to the mobility of the vehicle, the user’s demand for remote video browsing of the vehicle, GPS satellite positioning of the vehicle, and data interaction between the vehicle terminal and the platform is particularly urgent. The following is a brief discussion on the technical development direction of vehicle-mounted video surveillance system-level solutions.
1. Status Quo and Demand Analysis of Vehicle-mounted Video Surveillance System
1. The needs of wireless network adaptability
There are obvious differences between the vehicle-mounted wireless networked video surveillance system and the traditional fixed-point video surveillance:
1) The terminal IP address is not fixed and is restricted by a firewall; the IP address assigned to the wireless terminal by the operator may be changed at any time, and the firewall is restricted, and some ports are blocked;
2) The network bandwidth fluctuates greatly. Problems such as the number of users in the wireless network location, regional differences, and the degree of network optimization affect the future quality. The network bandwidth changes in real time, and may even drop to zero instantaneously. This requires the vehicle video terminal to adapt to this network. Bandwidth change mode;
3) The vehicle-mounted terminal moves in real time, the base station switches frequently, and the movement also causes the uncertainty of the video wireless network transmission. In order to improve the effect of wireless network transmission of in-vehicle video, it is necessary to improve the video coding algorithm and network transmission protocol according to the above-mentioned characteristics.
2. Requirements for multi-level data management
The core requirement of a large-scale video surveillance system is to achieve multi-level management. The vehicle-mounted video surveillance system should have the following functions:
1) Permission distribution management, for security considerations, it is necessary to classify users so that they can enjoy different permissions and assign different tasks;
2) Video streaming media forwarding technology, the video transmitted from the wireless network to the center should be distributed to different users to meet the requirements of multiple users to browse a video at the same time;
3) System expansion performance. The system should consider the requirements for expansion after the number of users in the future increases. On the basis of not changing the system topology, the system can be expanded only by increasing the number of forwarding servers.
3. Intelligent traffic management needs
Intelligent Transportation System (ITS) is a comprehensive transportation management system that effectively integrates a variety of advanced electronic technologies and applies it to the entire transportation management system. And management system.
As an organic component of the intelligent transportation system, the on-board video monitoring system can achieve the following functions: 1) Vehicle GPS positioning information management, the on-board video monitoring terminal can transmit GPS satellite positioning information to the management center in real time; 2) Real-time upload of vehicle information, on-board video terminal Real-time network transmission of vehicle conditions (such as engine speed and other information) during vehicle driving to the management center; 3) Data interaction function, 3G wireless network can not only meet the needs of vehicle video network transmission, but also realize information such as sound, text, and pictures. Interaction; 4) Other functions. Intelligent traffic management has a strong demand for real-time vehicle passenger flow statistics. The management center can have a rough understanding of the number of people in the vehicle through real-time video browsing.
4. Demand for advertising and entertainment video delivery
Advertising and entertainment broadcasting can obtain certain benefits for car owners. Today, with the fierce competition in the domestic vehicle advertising industry, personalized in-vehicle advertising services have become the general direction of the development of in-vehicle advertising. The main needs of advertisers are: 1) Real-time update of vehicle advertising data, 3G network can meet the needs of advertisers to update vehicle advertising in real time; 2) Advertising data feedback, advertisers need to statistically analyze the number of daily advertising, this The vehicle-mounted terminal is required to accumulate the amount of advertising broadcast and interact with the center; 3) Data interaction function. While placing advertisements, the system should have data interaction functions such as issuing announcements, weather forecasts, and road information.
2. System-level solution analysis
1. The structure of the vehicle video surveillance system
The vehicle-mounted video surveillance system consists of three parts: vehicle-mounted terminal, wireless network transmission subsystem, and central management platform.
(1) In-vehicle terminal (i.e., vehicle-mounted DVR), in addition to traditional video recording functions, should also have: GPS satellite positioning, 3G wireless network transmission, multimedia advertising, entertainment, video broadcasting and other functions.
(2) The wireless network transmission subsystem, the system can use the operator’s 3G network system to perform real-time wireless network transmission of data.
(3) The central management platform conducts unified management of the system, assigns user and terminal permissions, manages the streaming media forwarding of video data, and the interactive functions of data information.
2. Brief introduction of on-board video surveillance system functions
(1) Real-time video browsing
Real-time browse the video images uploaded by the vehicle terminal, and can adjust and manage the resolution, code stream, frame rate, image quality and other parameters of the video image.
(2) Alarm handling
Emergency alarm is a key point in the on-board video surveillance system. After the on-board terminal sends out an alarm signal, the client software should instantly pop up the video images inside and outside the car, and give an audible alarm. In addition, the system should also have alarm functions such as equipment failure alarm, overspeed alarm, blockage alarm, and cross-border alarm.
(3) Interactive management of data
The vehicle-mounted terminal and the central management platform can exchange information such as sound, video, pictures, text, etc., to meet the needs of users for interactive advertising and entertainment data.
(4) Vehicle dispatch management
The monitoring center performs positioning and scheduling management of vehicles, displaying the geographic location information of the vehicles on the large screen of the monitoring center, and performing reasonable scheduling management according to the road conditions where the vehicles are located.
(5) Data retrieval and analysis
The system can trace and analyze historical data, such as historical video recording retrieval and playback, GPS positioning track playback, alarm data retrieval and analysis, etc.
3. Key technical features of vehicle video surveillance system
(1) Wireless video firewall penetration technology
In order to break through the restrictions on wireless networks by operators, the system should support firewall penetration. The firewall penetration technology is similar to VPN technology. The vehicle terminal adopts the active connection mode for network connection, that is, a constant connection is established between the vehicle terminal and the central server. The channel usually transmits information such as heartbeat packets and GPS positioning; when video needs to be transmitted, the client uses the forwarding server to extract the video stream from the vehicle-mounted terminal.
(2) Low-bandwidth wireless network transmission technology for video streaming
Video wireless low-bandwidth wireless transmission technology includes the following points:
(1) Adopting a coding algorithm with high compression efficiency, currently the H.264 compression algorithm is mainly used;
(2) Video stream transmission can adapt to changes in wireless network bandwidth, and adjust the video sending frame rate and code stream in time;
(3) In order to ensure the security of video information, operators’ private networks can be used for data network transmission, such as China Telecom’s VPDN network, China Mobile and China Unicom’s APN network.
(3) Streaming media forwarding technology
Due to the limitation of the uplink bandwidth of the wireless network, in order to satisfy the monitoring center or other remote customers for simultaneous video access to the vehicle terminal, the monitoring center should be equipped with a streaming media forwarding server. The video access to the vehicle terminal is all forwarded through the streaming media forwarding server, so that the video service of the vehicle terminal only occupies one channel. Streaming media forwarding technology can relieve network bandwidth tension, improve the efficiency of response access, and obtain higher bandwidth utilization with the least time cost.
(4) Multi-server load balancing technology
There is a large amount of data interaction between the monitoring center and the vehicle terminal. Among them, GPS positioning information needs to take up a lot of database storage space. When the number of vehicles exceeds a certain number, one server cannot meet the requirements of system management, and the system should support multi-server load balancing. System load balancing means that multiple servers are processed in parallel in a symmetrical manner. Each server has an equivalent position and can provide services independently without the assistance of other servers; multi-server load balancing technology also provides perfection for seamless system expansion s solution.
(5) The choice of 3G video wireless network transmission system
Video network transmission mainly uses the 3G network uplink.
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