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Video surveillance experienced nearly 3 years of baptism and market cultivation. Along with the development of technology, especially with the rapid development and promotion of computer technology, all-digital network video surveillance systems have gradually replaced traditional analog surveillance systems as video surveillance systems. The mainstream. Video surveillance has gradually evolved from digitization and simulation to networking, high-definition, and intelligentization. Although the development prospects of network video surveillance are generally optimistic, but in practical applications, various constraints have greatly compromised the effectiveness of video surveillance.
Problem I: The video surveillance transmits a large amount of data The network bandwidth resources are insufficient
Network bandwidth is one of the bottlenecks that affect video surveillance. Under the existing conditions of IP resources and networks, bandwidth is always the most important factor that restricts the development of network video surveillance. With the continuous optimization of the image clarity of network video surveillance products, the bandwidth environment required for the surveillance system to transmit video streams is becoming stricter and stricter: the clearer the image, the higher the bandwidth conditions required to transmit video streams.
Therefore, the pressure on the network to monitor and control resources will inevitably increase, and even the performance of the decoding equipment will face enormous challenges. Especially when high-definition monitoring is about to emerge, large-scale domestic and foreign security companies are trying to solve the bandwidth environment. The problem is hard work. For example, the use of more efficient compression formats for front-end video, from MPEG-1 to MPEG-4 in foreign countries, and from H.261 to the current mainstream H.264 in China, the progress of each compression format will improve the compression efficiency. Several times the base number. It is in this situation that the dual-streaming technology of video surveillance systems has emerged and has become a popular trend.
Solution: How to solve network bandwidth problem with dual stream technology
Dual stream, as the name implies, means that the surveillance system composes the same video source into two video streams. The two video streams can be of the same video resolution or different video resolutions. The system can allocate corresponding video streams according to user requirements, thereby reducing the bandwidth pressure and effectively optimizing the network bandwidth environment.
Dual stream uses a high bit rate stream for local HD storage, such as QCIF/CIF/D1 encoding, and a low bit rate stream for network transmission, such as QCIF/CIF encoding, taking into account local storage and remote network transmission. Dual stream can realize two different bandwidth stream requirements for local transmission and long-distance transmission. Local transmission adopts high code stream for higher HD video storage, and long-distance transmission adopts lower code stream for adapting to CDMA/ADSL, etc. Network for higher image fluency.
Dual stream takes into account the image quality and transmission quality under the bottleneck of the existing network. It can break through the bottleneck of the network, flexibly select the stream format according to the network bandwidth, and achieve local high-definition storage, while the back-end low-stream network transmission. In fact, dual stream is a speed-up for network video surveillance. This kind of creatively expands the application of dual stream and realizes arbitrary code stream format selection and coding technology, enabling hundreds of thousands of cameras in large-scale video surveillance systems. Massive video, audio, storage, alarm, and management data can ensure the stable operation of the transmission system if the user can obtain limited network resources.
In fact, using a low bit rate stream to monitor the monitoring picture has been fully able to meet the monitoring needs. When the user needs to play back and recall the previous video, he can view the high-definition, high-quality screen on the local storage host, so that he can not only monitor but also analyze the source of the problem after the problem is discovered.
Problem 2: Mass storage for video surveillance
The surveillance system is the frontier of business applications, and the advanced and stable digital storage system is the basic support platform for the entire business application. With a reliable and advanced storage management system, the entire monitoring business data can be well preserved and can be easily performed. Query and use. Therefore, on the basis of digital surveillance video, the establishment of advanced monitoring data mass storage system is the inevitable trend of the current digitization and network development of the surveillance system. However, as a carrier for mass storage, the storage system is often a problem that plagues security vendors due to various factors such as performance, price, and compatibility.
In the video surveillance system, commonly used video surveillance storage types are generally divided into DVR storage, encoded direct-attached storage, and centralized storage. DVR storage can mount multiple hard disks, but this application will increase the system load and increase the failure rate. At the same time, due to data without necessary protection measures, data loss will often occur due to hard disk damage.
There are two ways to encode direct-connected storage: one is to connect the USB hard disk through the USB interface on the encoder, and the other is to configure the NAS (network attached storage) in the center to provide file-level storage for the front-end encoder. Space and share it with the central platform for call. With the use of USB hard disks, hard disks cannot be used in the field for a long time, so they are rarely used. However, NAS-attached methods can simultaneously support multiple host-side read and write operations, and have excellent sharing performance and scalability. NAS can be applied in a complex network environment and deployment is also very flexible. However, because NAS uses the CIF/NFS protocol for file-level data transmission, the network overhead is very large. Especially when the data is written, the utilization rate of the bandwidth is generally only between 20% and 40%, which is extremely harmful to the transmission network. Big pressure. So at present, NAS is generally used in small-scale network digital video surveillance systems or just for shared storage of some data.
Intelligent Application of Video Surveillance System
Centralized storage. In large projects, centralized storage is generally used to store monitoring data. In a centralized storage system, the SAN architecture is generally used. SANs provide a dedicated, highly reliable storage network that allows them to independently increase their storage capacity, as well as simplify management and centralized control (especially when all storage devices are grouped together). Because of these characteristics, the SAN architecture is particularly suitable for storage applications of large-scale network digital video surveillance systems and can handle the storage of thousands of thousands of front-end monitoring points. At present, SANs are mainly divided into FC-SANs (fiber storage area networks) and IP-SANs (Ethernet storage area networks). The difference between them is the difference between connecting lines and using data transmission protocols. Although FC-SAN adopts a dedicated protocol to ensure more stable and efficient transmission, its deployment method and construction cost are much higher than that of IP-SAN. Therefore, the IP-SAN is currently used in large-scale network digital video surveillance systems. - SAN architecture.
However, with the expansion of the scale of storage applications, the use of general-purpose storage devices, in particular storage devices with server architectures, has become increasingly problematic. Mainly in the following areas:
A surge in costs
In a large-scale project, there are too many front-end image information collection points, and the capacity of a single server is limited, resulting in the need to configure dozens or even hundreds of servers. This will inevitably lead to a sharp increase in construction costs, management costs, maintenance costs, energy costs.
Disk fragmentation issues
Since video surveillance systems often use a rollback write method, such out-of-order frequent read and write operations result in a large amount of disk fragmentation. As the usage time increases, the read/write performance of the entire storage system will be seriously affected, and even the storage system will be locked for read-only, and new video data cannot be written.
Performance issues
Due to the dramatic increase in the amount of data, the indexing efficiency of video data has also become more and more of concern. The data on TB, even hundreds of terabytes of data, often takes a few minutes to index.
It should be said that in recent years, with the vigorous development of the security industry, most domestic storage companies have also taken control of storage trains. However, at present, there are still many problems in monitoring storage devices that need to be resolved by security companies.
Question 3: Intelligent Application of Video Surveillance System
As far as the current situation is concerned, monitoring networks lack smart applications. The urban emergency system that is linked with large-scale video surveillance systems is one of the keys to solving public security and disaster prevention problems. It is necessary to establish a sound and reliable intelligent linkage command system. How to combine intelligence-based command management based on * business with security systems based on monitoring services is the difficulty of current urban security systems. This requires a higher level of system intelligence. At present, the image content analysis of the video surveillance network still needs to rely on artificial real-time viewing and manual access. With the expansion of the scale of surveillance networks, the massive increase of video data and the large number of people used for image surveillance and access have become a bottleneck restricting the full use of video surveillance network performance. It is getting more and more difficult to obtain useful information or intelligence from massive surveillance videos. From the perspective of practical applications, information should be searchable and queryable. However, the current application of surveillance video is mostly the reproduction and playback of surveillance scenes, and it is difficult to meet the needs of user information applications.
After the completion of a large-scale video surveillance system, its operating costs are also very high. I have heard that after a small police station has built a small monitoring system, the electricity cost for one year will be 10,000 yuan. It feels a lot of pressure. The operating costs of large-scale video surveillance systems account for only a small part of the electricity cost, and more is communication. , equipment maintenance and update costs. Since monitoring equipments are mostly operated continuously for 24 hours, the level of staff is not uniform, the equipment maintenance and update cycle is short, and the required expenses are relatively large. Therefore, the system's plan should comprehensively consider the construction costs and operating costs to facilitate the long-term operation of the system. The development of multi-domain applications for large-scale video surveillance systems is a development trend and necessity. Flexible use is made of intelligent video processing technologies such as face recognition, license plate recognition, traffic statistics, trajectory tracking, behavior analysis, and image retrieval to effectively expand the capabilities of prevention and control of the system. Multipurpose applications open up a wide range of sources of income, which is also required for its long-term stable operation.
Conclusion:
In recent years, video surveillance has become the main force in the development of the security industry, and more and more manufacturers have taken on video surveillance trains. Currently in the field of video surveillance, the trend of development is networked, high-definition, and intelligent. It is bound to have some problems among users. But video surveillance technology is not on the line, we can firmly believe that as the domestic video surveillance vendors deepen the understanding of the monitoring system, it will definitely put forward a complete solution, the development road will get better and better.
As an important security measure, video surveillance has a long history of development. With the launch of major projects such as the “Safe City,†“3111 Project,†“Global Eye,†and “Wide Vision†in 2006, the application of video surveillance in traffic, food, health and quarantine, customs, energy, finance, defense, and other fields has increased. More extensive. The emphasis on safety and security by the government and the people is also gradually strengthened. Video surveillance is undoubtedly one of the most popular among the government and the public.