Video surveillance source and digital process, high-definition wave surge, high-definition innovation technology introduction

The digital video surveillance market has developed rapidly and triumphed for more than a decade, and it is entirely a modern rhythm and momentum. Just look at the ubiquitous camera density in public places and you can see how much monitoring affects people's work, study and life. In the digital security surveillance market, "HD Smart" has become a hot spot and selling point that people are familiar with, and it will undoubtedly become a symbol of the modernization of video surveillance. However, is the visual experience and instant control that video surveillance brings to people perfect enough? How much space can you leave behind for postmodern development? This is exactly what this article is trying to answer. As a senior security person, in the post-modern video surveillance stage, still pay attention to the pursuit of higher realms. To this end, by reviewing the origin and history of security video surveillance, analyzing and expounding the important role of technological innovation in the development of digital video surveillance industry, I hope to pay attention to and look forward to the core technology trend that is beneficial to the future to improve visual effects and intelligent experience.

1 Video surveillance source and digitization process

Throughout the history of video surveillance industry development, the main pursuit is nothing more than image quality, resource efficiency and management benefits. The video surveillance start must be traced back to the closed circuit television system (CCTV), and the video surveillance application was expanded by the use of video recorders (VCRs). The visual perception of the monitoring increases as the number of resolution lines of the camera increases, and the video signal is output through the coaxial cable to be connected to the analog video device. Due to the transmission length and attenuation limitations of analog video cables, CCTV only supports local monitoring, and monitoring capabilities and scalability are extremely limited.

Digital video is a digital compression process for analog signals, which leads to the creation of a hard disk recorder (DVR). The DVR is a semi-analog-semi-digital solution that transforms video surveillance systems and resources. The DVR supports recording and playback, connects to an IP network, and connects to an analog camera via a coaxial cable. The quality of the early MPEG-1 video images was unsatisfactory, and the MPEG-2 effect was acceptable, but the storage was large and the price was high. Until the MPEG-4 and H.264 standards appeared one after another, the DVR became popular. Although the visual experience is still inferior to the high-quality CCTV system, there is still a high-definition transition. Digital video brings the rise of intelligent video analytics technology.

Network Camera (IPNC) is a combination of digital video surveillance digitalization and networking. As a pure digital solution, the video surveillance system is switched from centralized to distributed. Its HD resolution from 720P30 to 1080P60 is enough to challenge the traditional CCTV system. And the decoding is implemented by a network video recorder (NVR). At this point, the H.264 format realizes the digitization and networking of the video surveillance system, and the video surveillance can be built on the network system. Although digital networking has quickly become the dominant video surveillance, analog video technology has also made a difference in evolution.

2 The high-definition wave of video surveillance

When the video surveillance industry entered a mature stage of modernization, digital high-definition became the mainstream technology promoted by the industry, and there is no need to talk about the introduction. However, as the demand for applications continues to increase, the accuracy of image visual experience and intelligent analysis is demanding, and the constraints of digital video are constantly revealed. Digital video compression brings the original image information damage is an indisputable fact. The compression decompression process and the networked transmission must have a delay, especially for digital high-definition real-time processing. Therefore, back to the video front end, how to use the high-fidelity technology to transmit the original high-quality images is the key to solving the problem. Traditional coaxial cable has become the carrier of many technologies, which has achieved coaxial high-definition technology. The guarantee of video surveillance for coaxial high-definition lies in the fact that the high-definition image seen by the human eye has no loss and no transmission delay; secondly, the high-definition high-definition video signal has no distortion caused by compression to improve the intelligent video analysis. High reliability; third, real-time control and manipulation of high-quality imagery for a better visual experience and instant response. A new wave of coaxial HD is unfolding in digital and analog.

Drawing on the high visual experience of successful coaxial high-definition transmission technology in the field of broadcasting and television, the serial digital interface (SDI) from digital studio has gained new applications. The HD-SDI interface is matched with the back-end codec and video server, and directly projected to the large screen with the HD video matrix to fully exhibit the lossless HD effect. The HD-SDI solution can be upgraded based on the original analog monitoring system, especially suitable for real-time monitoring requirements. The coaxial cable transmits video and audio to simplify the analog system, and the transmitted control signals are transmitted in the same line, saving wiring costs. However, in general, the HD-SDI cost is still high. Although the standard is developed internationally, it is sensitive to the price in the security market.

The cost of a coaxial HD solution that returns to analog technology is low, so there are a variety of analog coaxial HD technologies, of which HDCVI, HD-TVI, and AHD are the most representative.

There are still some obstacles to the breakthrough in the promotion of analog coaxial high-definition cable transmission technology. Because of the large signal attenuation during transmission, the equalization recovery circuit used at the receiving end is difficult to achieve linearity, resulting in loss of brightness, color distortion, and sharpness. During long-distance transmission of signals, there will be reflections that cause blurring and smear of the image.

Second, it is the controllability achieved. The analog coaxial high-definition receiver needs to recover the clock signal to collect and receive video. If the clock information is insufficient, the clock deviation of the transmitting and receiving terminals must be strictly controlled. Generally, the frequency accuracy between the clock crystals at both ends is less than 25ppm. The signal-to-noise ratio of the recovered signal is random. With the increase of resolution and pixel clock frequency, the clock skew requirement of the transmitter is further improved, which is difficult to achieve in engineering, which makes the analog coaxial HD difficult to be upward compatible. This leads to compatibility problems between cameras and DVRs from different manufacturers, and even between different batches of products from the same manufacturer.

3 Video surveillance post-modern HD innovation

Since high-definition high-quality images will become the modern pursuit of digital video surveillance, the carrier that transmits 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 digital long-distance transmission technology different from analog coaxial high-definition, the video signal is first applied to the video signal with a proprietary high-performance algorithm for video lossless compression to reduce the signal bandwidth. The transmitting end performs error correction coding, and the receiving end performs error correction and decompresses and recovers the lossless video signal. Advanced video transmission technology (Advanced Video Transport, referred to as: AVT Technology) is a noteworthy technology, high performance algorithm used to achieve the lowest possible lossless compression of video bandwidth of 20MHz transmit high-definition video signal is half of 40MHz analog coaxial-definition programs , thus providing better line compatibility, such as the widely used SD D1 system.

Digital coaxial HD is more stable and reliable, without the need for an external video signal amplifier, without external ESD protection devices, and can be transmitted on both coaxial cable and 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 is consistent under good reductiveness, and there should be no problem such as smear which cannot be avoided by analog coaxial high definition. Compared with the high-definition network, the intra-frame visual lossless compression technology has almost no delay, and the transmission far-reaching system is not high in complexity. This is a feature of AVT technology.

As for supporting a five-category network cable to transmit four video signals, the AVT technology is used to receive four video signals without interference and ghosting. The clock deviation between the transmitter and the receiver is 500ppm, which is 20 times wider than the analog coaxial HD. Double, suitable for low temperature, high temperature, outdoor, vehicle and other high requirements. Compatibility with existing systems is also critical. If a DVR interface is compatible with AVT, HD-SDI or SDI cameras, it will be a great contribution to the overall digital video surveillance system. This requires 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 forward transmission SPI high speed protocol . The security monitoring system thus adds more possibilities, such as remote control and software update of the camera on the DVR side. With 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, the digital video surveillance industry has maintained a strong impulse to innovate after a golden era of modernization. Postmodernity will open another era of passion, but more is a rhythm full of reason and wisdom. Here you need to praise the innovators who are tireless and unwavering in the security field!

references:

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[2] Su Zhenwei. Design and implementation of 5MP integrated HD movement [J]. Electronic Products World, 2014(07): 15-17

[3] Wang Ying. Industry leaders talk about security monitoring trends [J]. Electronic Products World, 2013 (07): 11-17

[4] Michael Long. Processors that meet the needs of video analysis in the security and surveillance markets [J]. Electronic Products World, 2013 (07): 30-31

[5] Zheng Xiaolong. Look at security in the "object" in the cloud [J]. Electronic Products World, 2013 (07): 11-22

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