With the improvement of urban road traffic construction, the work pressure of the corresponding management departments is also increasing. It is obvious that human monitoring alone is not enough to solve the problems of speeding and overrun of vehicles, the operation of vehicles around busy road sections, the flow of pedestrians, traffic security and so on. Therefore, it is imperative to introduce remote monitoring information technology into traffic management.
The traffic video monitoring system is a window to understand the traffic situation and public security situation of the whole city. It is an indispensable subsystem of the public security traffic command system. The video monitoring system is an important part of the intelligent transportation system. The purpose of establishing the video image monitoring system is to timely and accurately grasp the traffic flow and public security situation of vehicles and pedestrians around the monitored intersection and road section, To provide rapid and intuitive information for commanders, so as to make accurate judgment and timely response to traffic accidents and traffic jams, video evidence collection of sudden public security incidents within the scope of monitoring, service for internal and external security work, and play a comprehensive management effect. Now the traffic industry is widely used in urban traffic intersection, key section monitoring and highway toll station monitoring.
According to the relevant documents provided by the project, according to the actual needs of the project, referring to the relevant international standards and national standards, and combined with the accumulated experience of many projects our company has been engaged in, this set of technical scheme is prepared.
1、 Design principles
The design of this project follows the principles of advanced technology, complete functions, stable performance and cost saving. The factors of construction, maintenance and operation are considered comprehensively, and there is room for expansion for future development, expansion, transformation and other factors. The design content of the system is systematic, complete and comprehensive; The design scheme is scientific, reasonable and operable.
2、 System functions and features
The system should not only be advanced, practical, mature and reliable, but also be open and expandable with reasonable investment and best benefit. Closed circuit television monitoring carries out centralized monitoring, control and management of field equipment, so that these equipment can operate safely, reliably and efficiently, maximize the role of intelligent management, create a safe, healthy, comfortable and pleasant environment that can improve work efficiency, save energy and reduce maintenance personnel.
（1） The system has the following functions:
The main task of CCTV is to monitor and control the situation and people flow in the important parts of the building, so as to obtain evidence and review the abnormal situation in real time and deal with it in time.
1. Realize all kinds of remote control signals
Pan tilt control: up, down, left, right
Lens control: zoom, focus, aperture
Video control: fixed point video recording and sequential video recording
Hood control: defrosting, fan, heating
2. Video signal timing, fixed-point switching, programming.
3. When viewing and recording images, characters should be distinguished and time (year, month and day) should be displayed.
4. Realize synchronous switching: power synchronization or external synchronization.
5. Receive the signal of each subsystem in the security system, and realize the control linkage or system integration according to the needs.
6. Internal and external communication.
7. When the security monitoring TV system is linked with the security alarm system, it shall be able to automatically switch, display and record the image signal and alarm time of the alarm position.
8. Power control
The camera shall be powered by the dedicated line from the security control room, and the security control room shall operate on and off. If it is really difficult to supply power to the cameras far away from the security control room, it can also be solved nearby. If the system adopts the power synchronization mode, it must be a reliable power supply in the same phase with the security control room.
（2） The system has the following characteristics:
H. 264 video coding standard is a low bit rate image compression standard designed for medium and high quality motion image compression. H. 264 adopts the common coding methods in motion video coding, and divides the coding process into two parts: intra coding and inter coding. The improved DCT transform and quantization are used in the intra frame, and the 1 / 2 pixel motion vector prediction compensation technology is used in the inter frame to make the motion compensation more accurate. After quantization, the improved variable length coding table (VLC) is applied to quantify the data for entropy coding, and the final coding coefficient is obtained.
H. 264 standard has a high compression rate. In CIF full real-time mode, the bandwidth occupied by a single channel is generally about a few hundred. The specific bandwidth occupied depends on the amount of motion of the picture. The disadvantage is that the image quality is relatively poor, and the occupied bandwidth varies greatly with the complexity of the picture motion.
3、 Introduction of system structure
（1） Front end equipment
The function of the front-end equipment is to realize the video signal acquisition and receive the remote control instructions from the monitoring center, and collect the video signal needed by the command center in real time and accurately. The front-end equipment selects integrated HD color camera according to the application environment, with integrated optical zoom lens, automatic white balance function, and supports manual and automatic aperture, focusing, shutter and gain control. All monitoring points can be equipped with PTZ, which is suitable for a wide range of monitoring. The front end needs to install high-definition video encoder equipment to send high-definition video image compression coding to the transmission network.
Baoqianli security video series products
（2） Transmission equipment
The transmission equipment completes the uplink transmission of video signal and the downlink transmission of control data. According to the development of existing communication technology, optical fiber transmission is selected as the main transmission means in the South China Sea traffic video monitoring system to realize the common network transmission of video signal, data and control signal. Optical fiber communication is efficient and safe, which can provide a stable transmission path for the whole video monitoring system. The transmission equipment uses the optical fiber transmission line of the traffic communication system to provide fast Ethernet interface for each front-end monitoring point. The effective transmission bandwidth is not less than 20MBps. The front-end equipment and the monitoring center equipment are respectively connected to the traffic communication system to complete the video transmission and control signal transmission.
（3） Monitoring center
As the core part of the whole video monitoring system, the equipment of monitoring center processes all video signals and issues control instructions. The monitoring center system is arranged in the traffic command center, which is composed of video management server, web server, storage management server, streaming media server, network storage server, high-definition video decoder and integrated monitoring client software. The display equipment is a splicing large screen, which is provided by the display system.
The monitoring center system can complete real-time switching display, digital video storage and online release of video signals sent by transmission equipment, and remote control of remote equipment according to the needs of traffic command and scheduling. At the same time, the video images in the construction process of the previous three phases of electronic police system should be unified managed by using the platform of this video monitoring system.
（4） Video storage mode
Disk array (NAS) equipment is used to store the network digital images transmitted from the front end to the monitoring center periodically.
4、 Overall requirement description of monitoring function
（1） Real time image playback
It shall be able to play the video in real time according to the specified camera equipment, support the video display, picture capture and local video recording on the computer, support the video display on the large screen and other display devices, and support multiple users to play the same video resource at the same time.
（2） Remote control
PTZ control of front-end camera can be realized by manual or automatic operation; It can set control priority, and it should have priority management for different levels of user requests.
（3） Storage and backup
The system can record retrieval information related to image information, such as equipment, time, alarm information, etc. Be able to store video information for at least 15 days; Special storage device can be configured for backup storage of information that needs long-term storage.
（4） Retrieval and playback of historical images
It can retrieve, replay and download historical image data according to camera equipment, time, alarm information and other elements; Playback supports normal playback, fast playback, picture pause, picture capture and jump.
（5） Human computer interaction of the system
It has intuitive, friendly and concise human-computer interaction interface; It has the functions of video screen display and information prompt; It can reflect the operation of the system itself, and give instructions for normal, alarm, fault and other states.
（6） User and authority management
The system has the function of authorizing and authenticating the login user, and defines the user’s operation authority on the device, the authority to access the data and the authority to use the software. The system can provide exclusive control of the camera equipment locking and unlocking function.
（7） Log management
The log includes system operation information and operation information, which can record online, offline and fault status in the system; It can record the time when the operator enters and exits the system and the main operation. Support the query and statistics function of log information.
（8） Open system interface
The system can provide interconnection interface with other information systems.
Editor in charge: GT