As early as the early 1980s, people had the awareness of on-board monitoring, and began to install video equipment in the car. Later, with the development of science and technology, an analog on-board video recorder appeared. This video recorder records and saves the operation of the vehicle by analog signals, which makes it impossible for the computer to set, manage and query its parameters, and hinders recording. The image recording time of the video tape is limited, and the video tape has to be replaced continuously during the running process of the vehicle, which brings unavoidable troubles to the storage. As a result, vehicle-mounted DVR came into being.
The so-called Vehicle DVR, which is based on 1U standard architecture, is installed in the location of the bus radio or CD player, and accesses 1-4 road images to monitor and record the situation of the vehicle. At present, the compression algorithms of Vehicle DVR are mainly MPEG4 and H.264.
Manufacturers have come up with a nice name for the embedded DVR used in cars, MDR or MVR (Mobile Digital Recorder or Mobile Evideorecorder). As a result, "Mobile" has become the biggest difference between vehicular DVR and ordinary DVR. It is precisely because the vehicle DVR has this mobility that it provides a good condition for vehicle safety monitoring in the process of moving.
Is it possible to use ordinary DVRs for on-board surveillance? The answer is No. Although the embedded system is used like the ordinary DVR, the vehicle DVR technology is more complex than the ordinary DVR, and the key to solve the problem is different. Because the vehicle will inevitably encounter vibration, dust, large power supply and other issues in the process of moving, these are doomed to the application environment of vehicle-mounted DVR is worse than ordinary DVR.
Vehicle interior environment is harsh, multi-technology integration "stable" winning ticket
It is understood that in order to ensure that the bus can still be stored smoothly in operation, the vendors strengthen the technology of vehicle DVR mainly including shock proof, voltage-stabilized current, heat dissipation, wireless transmission and so on. The perfect integration of these technologies is to further improve the stability of vehicle DVR storage.
Because of the different vehicle condition and road condition, the anti-seismic technology has become the most basic requirement for the vehicle DVR, including the whole machine vibration reduction, hard disk frame vibration reduction, hard disk vibration reduction and other links, to achieve the whole vehicle DVR vibration reduction processing.
Among these shock absorption links, hard disk vibration reduction is the most important. This is because the harddisk is the most easily damaged part of the DVR. Once the hard disk is damaged, it can not store the situation in the car, so the problem of shock absorption of the hard disk is particularly important.
At present, spring and rubber cushion are mostly used as shock-proof materials in the market. Although they can play a certain role in the vertical direction of force, the vibration direction is irregular in the driving state (especially in bad road conditions). Long-term use will inevitably lead to equipment failure. Spring and rubber pad can not absorb the energy of vibration, but will store this energy, when to a certain extent, will cause greater rebound. According to him, there is a rubber cushion filling bag method, mainly using the advantage of oil compression smaller than air, in order to achieve better shock absorption effect.
In addition, some manufacturers also have the design of hard disk suspension or chassis suspension for vehicle DVR, which is to achieve the "suspension" state of the hard disk or the whole chassis in order to achieve the effect of shock absorption.
Regulated power supply
In addition to shock absorption, another important technology in vehicle DVR is power stability. Because the vehicle will brake, climb, ignite and other actions in the course of driving, this kind of behavior will cause the output voltage of the vehicle to fluctuate in different amplitudes, which will easily cause the phenomenon of burning down the vehicle equipment, so the vehicle DVR itself must have the ability of wide voltage input to adapt to this voltage change.
It is understood that in the process of bus operation, there will be a great change in temperature difference. Many buses install DVR under the driver's seat or in the closed space at the top of the driver's seat, which puts forward higher requirements for the performance of the vehicle DVR.
However, some people in the industry believe that because of the specific requirements of the national and local governments for GPS positioning system and related documents, many transport companies are mandatory equipped with GPS positioning system, so the GPS function added by vehicle DVR is more in line with the needs of buses.
Future: Make Storage Smart
From the above introduction, it seems that the vehicle DVR has been perfected. However, only through continuous innovation can the market of DVR be developed faster. From the interview, the author understands that manufacturers have begun to consider intelligent processing of some functions of DVR, such as increasing the functions of face recognition, number statistics, feature recognition, increasing the practicability and pertinence of the vehicle system, so as to make the storage more intelligent.
When a car breaks the law, the police can only catch the perpetrator by carefully observing his appearance, clothing and so on. When the perpetrator appears again, they can catch him according to their judgement. This is a very time-consuming and inflexible way. Moreover, the management center personnel will inevitably Miss certain events when they watch video playback or real-time video streams. Therefore, it will be the future development direction to implant the "nervous system" into the vehicle DVR to replace the human brain for analysis and judgment.
For the advantages of adding intelligent analysis technology, intelligent analysis technology uses the powerful data processing function of computer to analyze the massive data in the video screen at high speed, filter out the information that users do not care about, and only provide useful key information for the monitors, thus effectively saving the bandwidth and greatly improving the available network bandwidth.
More importantly, intelligent video technology can detect suspicious activities, events or behavior patterns by analyzing real-time or recorded video streams, which can make video surveillance to search for criminal suspects after the incident into an assistant means to prevent crime at that time.
Intelligence will play an increasingly important role in future vehicle DVR storage applications. Manufacturers will continue to develop more innovative technologies to ensure the integrity and availability of recorded data according to the needs of users.