The digital video surveillance market has been developing at a high speed for more than a decade, and it is advancing vigorously. It is completely a modern rhythm and momentum. Just look at the ubiquitous camera density in public places, and you will know to what extent monitoring affects all aspects of people's work, study and life. In the digital security surveillance market, "HD Intelligence" has become a familiar hotspot and selling point, which will undoubtedly become a symbol of modern video surveillance. However, is the visual experience and real-time control brought to people by video surveillance perfect? How much room can be left for post-modern development? This is exactly the question that this article is trying to answer. As a senior security guard, in the post-modern video surveillance stage, he is still concerned about pursuing a higher level. To this end, by reviewing the origin and history of security video surveillance, analyzing and elaborating the important role of technological innovation in the development of the digital video surveillance industry, I hope to pay attention and look forward to the core technology trend that is beneficial to the future to improve visual effects and intelligent experience. Throughout the development of video surveillance industry, the main pursuit is nothing more than image quality, resource efficiency and management benefits. The beginning of video surveillance must be traced back to the closed-circuit television system (CCTV), and later the use of video recorders (VCR) will expand video surveillance applications. The visual experience of monitoring increases as the number of resolution lines of the camera increases. The video signal is output through the coaxial cable and connected to the analog video equipment. Due to the limitation of analog video cable transmission length and attenuation, CCTV only supports local monitoring, with extremely limited monitoring capabilities and scalability. Digital video is the digital compression of analog signals, which gave birth to a hard disk video recorder (DVR). DVR is a semi-analog-semi-digital solution that transforms video surveillance systems and resources. DVR can support video and playback, connect to IP network, and connect with analog camera through coaxial cable. The early MPEG-1 video image quality was unsatisfactory. Although the MPEG-2 effect was acceptable, the storage capacity was large and the price was high. It was not until the emergence of the MPEG-4 and H.264 standards that the DVR became popular. Although the visual experience is still at a disadvantage compared to high-quality CCTV systems, there is still a transition to high-definition after all. Digital video brings the rise of intelligent video analysis technology. IP Camera (IPNC) is a combination of digital video surveillance digitization and networking. As a pure digital solution, the video surveillance system is shifted from centralized to distributed. Its high-definition resolution from 720P30 to 1080P60 is enough to challenge the traditional CCTV system. , And decoding is implemented with a network video recorder (NVR). At this point, the H.264 format realizes the digitization and networking of the video surveillance system, and video surveillance can be built on top of the network system. Although digital networking has quickly become the dominant video surveillance, analog video technology has also made some progress in the evolution. When the video surveillance industry has entered a mature modernization stage, digital high-definition has become the mainstream technology promoted by the industry, and there is no need to talk about the introduction. However, with the continuous improvement of application requirements, the requirements for image visual experience and intelligent analysis accuracy are demanding, and the constraints of digital video are constantly revealed. It is an indisputable fact that digital video compression brings original image information damage. There must be a delay in the compression and decompression process and networked transmission, especially for digital high-definition real-time processing. So, going back to the front end of the video, how to transmit the originally collected high-quality images with high-fidelity technology is the key to solving the problem. The traditional coaxial cable has become the carrier of multiple technologies, which has achieved coaxial high-definition technology. The guarantee of coaxial high-definition video surveillance is that, first, the human eye sees no loss of high-definition images and feels no transmission delay; second, high-quality high-definition video signals have no distortion to improve intelligent video analysis. High reliability; third, real-time control and manipulation of high-quality image frames to obtain a better visual experience and immediate response. A new wave of coaxial high-definition shocks unfolded in digital and analog. Drawing on the extremely high visual experience of the successful coaxial high-definition transmission technology in the field of radio and television, the serial digital interface (SDI) from the digital studio has been newly applied. The HD-SDI interface is used to match the back-end codec and video server, and the high-definition video matrix is ​​directly projected onto the large screen to fully display the lossless high-definition effect. The HD-SDI solution can be upgraded on the basis of the original analog monitoring system, and is especially suitable for occasions with high real-time monitoring requirements. Simultaneous video and audio transmission on the coaxial cable simplifies the analog system, while the transmitted control signals are transmitted on the same line, saving wiring costs. However, in general, HD-SDI is still relatively expensive. Although the standard is developed internationally, it is very sensitive to price in the security market. The cost of coaxial high-definition solutions that return to analog technology is lower, so there are a variety of analog coaxial high-definition technologies, of which HDCVI, HD-TVI, and AHD are the most representative. There are still some obstacles that need to be broken through for the promotion of analog coaxial HD cable transmission technology. Because there will be a lot of signal attenuation during the transmission process, the equalization recovery circuit used at the receiving end is difficult to be linear, resulting in brightness, color distortion and loss of clarity. During long-distance signal transmission, there will be reflections that cause blurring and smearing of the image. Secondly, the controllability. The analog coaxial HD receiver needs to recover the clock signal to collect and receive the video. If the clock information is insufficient, the clock deviation of the sender and receiver must be strictly controlled. Generally, the frequency accuracy between the clock crystals at both ends must be less than 25ppm at 720P. The signal-to-noise ratio of the recovered signal is random. With the increase of resolution and pixel clock frequency, the clock deviation requirements of the sending and receiving ends will be further increased, so that it is difficult to achieve in the project, which makes it difficult to be upward compatible with analog coaxial HD. As a result, compatibility problems are easily caused between cameras of different manufacturers and DVRs, and even between different batches of products from the same manufacturer. Since high-definition high-quality images will become the post-modern pursuit of digital video surveillance, the carrier that bears the transmission of high-fidelity video images is a coaxial cable, but this must be a digital coaxial high-definition technology with more innovative highlights. The technical bottleneck of analog coaxial is indeed difficult to eliminate, but there is a way to continue to develop digital coaxial. Using a digital long-distance transmission technology different from analog coaxial high-definition, the video signal is first subjected to a proprietary high-performance algorithm for lossless video compression in order to reduce the signal bandwidth. The transmitting end performs error correction coding, and the receiving end performs error correction and decompresses to recover the lossless video signal. Advanced Video Transport technology (Advanced Video Transport, AVT technology for short) is a technology that deserves attention. The high-performance algorithm used to achieve lossless video compression can transmit a high-definition video signal with a minimum bandwidth of 20MHz, which is half of the 40MHz analog coaxial high-definition solution. , To provide better line compatibility, such as the widely used standard definition D1 system. Digital coaxial HD is more stable and reliable in that it does not require an external video signal amplifier or an external ESD protection device, and can be transmitted on a coaxial cable or a twisted pair. The video signal has no distortion and no attenuation due to digital transmission. No matter how far the transmission is, the image quality remains consistent under good reproduction, and there should be no problems such as smear that is unavoidable by analog coaxial high-definition. Compared with the intra-frame visual lossless compression technology used in network high-definition, there is almost no delay, and the complexity of the system is not high even if it is transmitted farther, which are the characteristics of AVT technology. As for supporting a five-category network cable to transmit four video signals, there is no interference and ghosting between the four video signals received by AVT technology. The solution requires a clock deviation of 500ppm between the transmitter and the receiver, which is wider than the analog coaxial HD 20 Times, suitable for low temperature, high temperature, outdoor, vehicle and other demanding environments. Compatibility with existing systems is also critical. If a DVR interface can be compatible with AVT, HD-SDI or SDI cameras, it will be a great contribution to the overall digital video surveillance system. This requires providing a complete system solution based on AVT technology, supporting up to 96k sampling rate 2/4 channel forward audio and 8k sampling rate single channel reverse audio, as well as bidirectional UART, I2C protocol, and can forward SPI high-speed protocol . The security monitoring system thus adds more possibilities, such as users can remotely control the camera and update the software on the DVR side. Through the splitter and adapter chip solutions provided by AVT technology, the composition of a larger-scale ultra-long-range high-definition video surveillance system will become a breeze. All in all, after a golden modern era, the digital video surveillance industry still maintains a strong impulse for innovation. Postmodern will open another era of passion, but more is a rhythm full of reason and wisdom. Here we need to give praise to the tireless and unswerving innovators in the field of security! references: [1] Feng Yanjun, Zhang Jianguo, Yi Zilin. FPGA-based source-system composite encryption technology and its application [J]. Electronic Product World, 2013 (07): 27-30 [2] Su Zhenwei. Design and implementation of 5MP integrated high-definition movement [J]. Electronic Product World, 2014 (07): 15-17 [3] Wang Ying. Industry leaders talk about security monitoring trends [J]. Electronic Product World, 2013 (07): 11-17 [4] Michael Long. 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