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DVR common compression mode brings more development of on-board monitoring
Jan 07, 2019

With the development of chip technology, higher performance CPU makes DVR faster and more powerful. At present, the main compression technologies of DVR in the market are MPEG-4, H.264 and M-JPEG. MPEG-4 and H.264 are the most common compression modes in China, and H.264 has become the mainstream because it is more suitable for the requirements of network transmission.

H.264 is a high performance video coding and decoding technology. H.264 is built on the basis of MPEG-4 technology. Its coding and decoding process mainly includes five parts: inter-frame and intra-frame prediction, transformation and anti-switching, quantization and anti-quantization, loop filtering and entropy coding. It is the latest and most promising video compression standard since the release of MPEG-2 video compression standard in 1995. Through this standard, the compression efficiency under the same image quality is more than two times higher than that of the previous standard, and many advanced technologies are added, such as hierarchical design, high precision, multi-mode motion estimation and unified VLC.

Compared with previous MPEG-2 and MPEG-4, H.264 has the greatest advantage of high data compression ratio. Under the same image quality conditions, the compression ratio of H.264 is more than 2 times of that of MPEG-2 and 1.5-2 times of that of MPEG-4. At the same time, the coding technology also has the following features: precise matching decoding to avoid error accumulation; strong fault tolerance; delay gradient to adapt to more application environments. So H.264 is the mainstream video coding technology in DVR today.

From the current market point of view, DVR is inexpensive, mature products, and still widely used, mainly in projects with fewer monitoring points and lower level requirements. However, due to the performance limitations of codec devices, the mode of sequential hard disk writing is generally adopted, and RAID redundancy technology is not applied to protect data. With the continuous increase of hard disk capacity, the probability of key data loss caused by single hard disk failure is increasing synchronously. Most DVRs only have 4-8 hard disks, which have very small capacity and poor compatibility, and can not meet the requirements of monitoring data stored in large stream for several months nowadays. In addition, the structure of DVR does not have the ability of flexible expansion, or even can not expand, resulting in limited hard disk capacity can not be. To meet the growing needs of users.

With the rapid increase of market demand, DVR will develop in the future in the following aspects:

(1) Higher resolution. At present, high-end DVR generally has D1 encoding effect, but it is still in the stage of development. I believe that there will be a clear and high-definition encoding technology which can take into account network transmission in the future. Of course, it also depends on the development of hard disk capacity, as well as the change of network bandwidth and cost.

(2) More functions. More abundant software interfaces are needed to facilitate the access of large-scale systems and form a comprehensive monitoring system, which will be more conducive to the application and popularization of products.

(3) Better environmental adaptability. Monitoring environments are generally more complex, as far as temperature is concerned, the difference may be - 20 - 50 degrees Celsius, which requires DVR to adapt to a variety of environments, with better performance.

(4) The equipment is more intelligent. For example, intelligent technologies such as biometric technology, behavior analysis technology and video search technology are used to make the equipment more intelligent and realize the change of video surveillance from passive defense to active prediction.

In a good market environment, what developments will bring about in-vehicle surveillance video recorders?

For on-board monitoring, the biggest dilemma is the challenge of stability. The stability requirement of the equipment itself, as well as the response to high temperature or frequent vibration in the vehicle environment, are unavoidable problems of the vehicle monitoring and video equipment. With the gradual "correction" of vehicle monitoring applications, especially for the further demand of high-definition equipment and stability. The quality of VCRs is no longer measured by the role of "pilot".

Therefore, besides guaranteeing normal work in special environment, as an important monitoring terminal, how to improve the performance of the equipment is also an inevitable development requirement of the future vehicle monitoring storage equipment.

In the field of transportation, intelligent vehicle monitoring can use the vehicle as a mobile carrier. Mobile detection, object tracking and license plate recognition on the road are also another reliable statistical method for traffic flow or road condition.

Recently, many vehicle-mounted hard disk recorders have added intelligent modules for face detection and license plate recognition, which can analyze and process face information and license plate information. In the future, other intelligent modules will be added according to the needs of customers in different industries. However, how to achieve the linkage with the system and play its role more robustly is still the vehicle monitoring storage technology needs to be further improved.

In fact, for the management of intelligent cities, bus positioning is the research direction of many cities. At present, from the point of view of a single positioning function, today's positioning application is no longer a trouble. However, if we can combine positioning with real-time monitoring, it is actually a more cost-effective application.

Objectively speaking, on-board monitoring has become a trend of current monitoring expansion, which is an effective and irreversible application in both safe city and monitoring field. Therefore, it also puts forward higher requirements for hard disk video recorders. Although the application of on-board monitoring is still very preliminary and its functions are very limited, the application of this road is doomed to be long-term and broad.

epilogue

At present, the video surveillance system mainly develops in two directions: First, DVR will be more "refined" in terms of product performance and humanization, making DVR more widely used in various fields of security industry. Secondly, DVR will support and match more products and equipment, compete with NVR and serve the development of video surveillance industry.


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