[ Pacific Security Network News
Initially, the concept and standard of "HD" was proposed by the broadcast and television industry. In the 1960s, NHK, the Japanese national broadcaster, began researching HD; in the early 1990s, NHK and Sony completed research and began piloting high-definition televisions in analog mode. However, due to various reasons, Europe does not accept Japanese research. This article introduces HD camera technology to everyone, first of all to explain its concept. In the mid-1980s, companies such as Philips also jointly completed a high-definition research program. However, in 1990, the United States launched the digital HDTV HDTV in one fell swoop, and later surpassed Japan and Europe. From then on, everyone acknowledged that digital TV is the future development direction of HD. At present, high-definition digital TVs on the market can be divided into two camps, namely the European Digital Television Broadcasting Union DVB and the American Advanced Television Systems Alliance ATSC.
HD is not an easy task for video surveillance. It involves a lot of aspects of the monitoring system, from the front-end camera to the transmission, to the record storage and display equipment, in order to reach the "high-definition" indicators need to be adjusted accordingly, as long as one link can not meet the requirements, it will not reach the "HD "Claim.
HD camera technology standard
High-definition video surveillance has developed rapidly in recent years, mainly to solve the problem that people cannot see the details in the normal monitoring process. "High definition" means "high resolution". The definition of high definition comes from the digital TV field. HDTV, also known as "HDTV", is a high definition TV standard format determined by the American Society of Motion Picture and Television Engineers. The definition of television is measured by the number of horizontal scanning lines. Its centralized HD division is as follows:
(1) 1080i format, which is a standard digital TV display mode, 1125 vertical scanning lines, 1080 visible vertical scanning lines, 16:9, resolution 1920Ã—1080, interlaced/60Hz, horizontal frequency 33.75KHz.
(2) 720p format, standard digital TV display mode, 750 vertical scanning lines, 720 visible vertical scanning lines, 16:9, resolution of 1280 Ã— 720, progressive / 60Hz, line frequency is 45KHz.
(3) 1080p format, 16:9, resolution is 1920Ã—1080 progressive scan, professional format.
HDTV refers to the TV standard that supports 1080i, 720p and 1080p.
At present, the traditional monitoring system in the security industry can reach the standard definition. After digital encoding, it can generally reach the resolution of 4CIF or D1, which is about 440,000 pixels, and the resolution is between 300 and 500 TV lines. IP surveillance of the camera, if you want to achieve the clarity of 800 TV lines, then the resolution of the network camera should reach at least 1280x720, about 900,000 pixels; if you use a 2 megapixel network camera, you can achieve ultra high definition images. A network camera with a 16:9 aspect ratio is required, which corresponds to a resolution of 1920x1080 and a 4:3 aspect ratio network camera with a resolution of 1600x1200. The security industry is more borrowing the HD division standard in the TV field, commonly known as "HD" and "SD". Network cameras with resolutions up to 1080i and 720p have appeared in the security market because the network provides a high guarantee for the transmission of high-definition video. Of course, there are also analog cameras with high-definition transmission interfaces, such as guns or all-in-ones with Y/Pb/Pr and VGA interfaces.
Therefore, here we borrow a radio and television standard: a camera capable of reaching megapixels, with a 1080p resolution display device and corresponding transmission channel, can form a monitoring system that can be called high definition. There is currently no universal HD standard in the security video surveillance industry. Some manufacturers believe that the image reaches D1 is high-definition, and some manufacturers believe that more than 480 lines are high-definition, and there are different opinions. Here we can look at the DVR national standards. In 2006, the National Standard for Video Surveillance and Surveillance Digital Video Recording Equipment GB 20815-2006 issued by the General Administration of Quality Supervision and Inspection of the People's Republic of China stipulates that the DVR is classified into Class A (resolution not less than 4CIF) and Class B (resolution less than 4CIF). According to the evaluation criteria of the above manufacturers, the A-class products in the DVR are high-definition products, and the B-class is a general-purpose product, that is, 4CIF (resolution 704Ã—576) is high-definition, and CIF (resolution 352Ã—288) is ordinary. Sharpness.
With the advancement of science and technology, "HD" technology will inevitably be introduced into the field of video surveillance, and the HD standard of the video surveillance industry will continue to improve.
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