New heights of analog-digital hybrid applications in video surveillance systems (full text)

        With the rapid development of computers, networks, image processing and transmission technologies, video surveillance technology and video surveillance systems are also constantly upgrading. The demand for video resource integration and application and high-definition video surveillance is the strongest driving force for the continuous upgrading of the entire video surveillance system 　　

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Early analog-digital hybrid applications　　

       take the traditional analog monitoring system as an example. Analog monitoring technology has complete and mature solutions. The mature technology and stable system have always been the basis for it to occupy an important market share in the domestic and international monitoring field. However, it is limited by inherent technical limitations in video clarity, video transmission distance, control deployment, business applications, etc., which affect its application scope and subsequent development. In order to first solve the problem of video resource integration and more conveniently and effectively manage video resources in a unified manner, analog monitoring systems often convert analog signal encoding into digital form to achieve the purpose of video resource unification. This is also an early analog-digital hybrid application, as shown in the topology below. 　　

The development of analog-digital hybrid applications 　　

       The analog-digital hybrid architecture introduced above is the most commonly used architecture since the popularization of embedded digital hard disk recorders and encoders. It not only protects the investment of the original analog monitoring system, but also provides a solution for the unified management of video resources. However, at the current stage when high-definition is gradually popularized and the demand for high-definition intelligence is becoming stronger and stronger, the clarity, video analysis and other performance and functions of the products that constitute this system are obviously not in line with the needs of the rapid development of video monitoring systems. 　　

       As shown in the figure below, channels 9, 11 and 12 are all analog standard definition effects, while channel 10 is a coaxial high-definition image effect. The effect of analog standard definition is only to see the general scene, see whether there are people, and see the direction of people, while the effect after the high-definition upgrade is significantly improved, and more details can be seen, such as vehicle information in the scene, character feature information, etc. 　　
        In order to seamlessly connect the original analog monitoring system, smoothly upgrade to HD, and inherit the real-time, safe, stable and reliable advantages of the original analog monitoring system, the industry has been constantly introducing new application technologies, such as Sony's 960H analog HD, and the introduction of HDSDI technology into the field of video surveillance for security. 　　

       The effect of 960H analog HD has been proven to be unable to meet the needs of true HD, and the emergence of HDSDI has made the industry shine. HDSDI uses high-quality coaxial cables to transmit digital video signals and provides video images up to 720P\1080P. Its architecture deployment and control habits are basically similar to those of the analog standard definition system. With the exclusive SDI optical terminal and SDI digital hard disk recorder, it can be easily integrated into the original video surveillance system, inheriting the real-time and security characteristics of the analog monitoring system. This hybrid HD in architecture has broken through the traditional "analog-digital" hybrid. However, in my opinion, HDSDI technology has not really fully replaced the analog system. The limitations of HDSDI front-end transmission distance, construction precision, high cost and other factors have limited the popularity of HDSDI in the market, making it difficult to effectively upgrade the analog part of the analog-digital hybrid system. 　　

       In this case, the high-definition development of the analog-digital hybrid system has always been dominated by network high-definition, while the analog monitoring system based on coaxial cables has been unable to solve the coverage and inheritance of the original system. 　　

       Coaxial high-definition technology is a dark horse that has emerged in the past two years and has become one of the most popular basic technologies in the global security market in the past two years. Coaxial high-definition technology supports 720P\1080P and even higher 4 million and 4K image resolutions, and supports coaxial control signals and audio signals composited on video signals, and can ensure ultra-long-distance transmission of high-definition video signals on coaxial cables. This technology effectively solves the inheritance of the characteristics of the original analog standard-definition system and effectively realizes the demand for high-definition analog system architecture. After its launch, it quickly gained popularity in the global market, and new analog-digital hybrid applications based on coaxial high-definition technology also grew rapidly.

New development 　　

       At the end of 2014, the "Technical Requirements for Security High-Definition Video Surveillance Systems GA/T 1211-2014" formulated by the National Security Alarm System Standards Committee was officially approved and implemented in April 2015. The standard states that "high-definition video surveillance systems are mainly composed of three parts: front-end, transmission, and terminal. According to the different transmission methods, they are divided into three types: IP network type, non-IP network type, and hybrid type." 　　
       Among them, the IP network type high-definition video surveillance system refers to a system in which video signals are transmitted via an IP network, and its logical architecture is shown in the figure above; the non-IP network type high-definition video surveillance system refers to a system in which video signals are transmitted via other means other than an IP network, and its logical architecture is shown in the figure below: 　　
       The high-definition video surveillance systems of these two architectures were once very popular in the market where only IP network high-definition and HDSDI high-definition systems were available. In particular, the IP network high-definition system relies on mature network transmission methods and accounts for the majority of newly built high-definition systems. Non-IP network high-definition video surveillance also occupies a considerable market share in some special fields due to cost and technical implementation methods. 　　

       The standard "Technical Requirements for Security High-Definition Video Surveillance Systems GA/T 1211-2014" also specifically introduces a third type of high-definition video surveillance system, namely the hybrid high-definition video surveillance system. The standard mentions that the hybrid high-definition video surveillance system is a combination of IP network and non-IP network systems. According to actual needs, the hybrid high-definition video surveillance system can have a variety of combination modes, and the main architecture is shown in the figure below: 　　
       As can be seen from the topology, the hybrid high-definition video surveillance system has changed the situation in which there is only a single architecture in the previous solution. The designer or customer can use the current mainstream high-definition technology according to the actual needs of their own projects to realize the architecture of the high-definition video surveillance system. This architecture is closer to the actual pain points of customers. 　　

       In the construction of some domestic security projects, the video surveillance system is a must-build subsystem in many industries. Due to the phased construction of the system and different construction years, there are generally the situation of analog standard definition in the first phase, SDI high definition in the second phase, and network high definition in the third phase. The situation of analog-digital hybrid can be said to be very common in various industries at present. Taking the public security as an example, the early Sky Eye projects were mostly based on analog standard definition, and the subsequent newly built first-level points were mostly based on high definition. The upgrading and transformation of standard definition resources in the project is a difficult point; taking the domestic subway track construction as an example, Beijing, Shanghai, Guangzhou, and Shenzhen are at the forefront of track construction, but the video surveillance system is still an early analog standard definition system. Although the integration of system resources has been completed, the hard defect of clarity still limits the subsequent business expansion in these projects. How to achieve high-definition upgrade is also a pain point for users. What kind of high-definition access method should be chosen to ensure both the newly built high-definition effect and the smooth high-definition upgrade of the previous system is currently the most concerned issue for users in various industries. 　　

       In the GA/T 1211-2014 standard, the hybrid high-definition video surveillance system part provides reference basic technologies: 　　

       6.1.1 System equipment should comply with the requirements of the current national standards and meet the environmental adaptability and electromagnetic compatibility requirements of the site of use. 　　

       6.1.2 The performance and technical requirements of various supporting equipment of the system should be coordinated to ensure that the image quality of the high-definition video surveillance system meets the system performance indicators. 　　

       6.1.3 Equipment involved in video encoding and decoding in the system should adopt video encoding and decoding standards such as SVAC, H.264, and H.265, and the SVAC video encoding standard should be used first. 　　

       6.1.4 Equipment involved in information exchange, transmission, and control over IP networks in the system should comply with the GB/T 28181 standard. 　　

       6.1.5 The equipment involved in non-IP network in the system should support interfaces such as HD-SDI and HD-CVI that comply with relevant standards such as IEC 62676-3, HDcctv 2.0 S1200 or HDcctv2.0 S1205. 　　

       In the hybrid high-definition video surveillance system, the standard has given the recommended access method or interface technology, and the HDCVI coaxial high-definition technology can effectively cover and inherit the original analog standard-definition system in this hybrid high-definition system with the characteristics of HDCVI coaxial high-definition technology, and has a strong technical advantage in the construction of hybrid high-definition video surveillance system. 　　

        Note: 　　

       High Definition Video Surveillance System 　　

       is a video surveillance system with a system image resolution greater than or equal to 1920×1080 and a system image horizontal resolution greater than or equal to 800TVL. 　　

       Note: When the system image resolution is greater than or equal to 1280×720 and less than 1920×1080, and the system image horizontal resolution is greater than or equal to 600TVL, it is called a quasi-high-definition video surveillance system. 　　

       HDCVI: High definition composite video interface 　　

       HD-SDI High Definition Serial Digital Interface SVAC Surveillance Video and Audio Coding 　　

With 　　

       the continuous development of social economy and the continuous progress of technology, higher requirements are put forward for the accuracy, effectiveness, reliability and convenience of video surveillance systems. 　　

       Specifically, the first is that the degree of industrialization and professional application will continue to deepen. Traditional security monitoring will definitely develop in the direction of monitoring such as business nature required by industry demands, and higher requirements are also put forward for the coverage and implementation distance of the same system. The coverage rate of multiple points and wide coverage and the professional demands of different industries will be the key to the construction plan of the entire high-definition video surveillance system, and the business capabilities of basic technologies will also be more and more required. 　　

       The second is the integration and utilization of video resources and professional business resources to achieve centralized optimization processing of big data, achieve the effect of building for use, and transform video resources into valuable resources. 　　

       These two requirements are exactly in line with the needs of video resource integration and application and high-definition video surveillance. High-definition and resource integration have become the basic necessary conditions to meet system requirements. Based on the actual application of customers, we now have more high-definition technology options to meet the different construction needs of customers. These will be where hybrid solutions will be focused. High-definition hybrid video surveillance systems will also be elevated to a new level in the future development of the industry.