" Let's see more clearly " , this is already a very urgent demand put forward by many users when using digital video surveillance products. Mark Colstein , president of MultiMedia Intelligence , an authoritative IT market research company in the United States, mentioned four major technical factors driving the development of the video surveillance equipment market : megapixel cameras, high-performance codecs, powerful analysis technologies, and easy access from CCTV. ( CCTV ) All underlying technologies that migrate to IP / networked video surveillance. From his words, we can see that the megapixel camera, high-performance codec and IP network technology of the four major technical factors are related to high-definition products, representing the aspects of acquisition, codec, and network transmission in high-definition products Development direction.
What is HD?
What is HD? In recent years, more and more manufacturers have begun to launch " HD " products. The monitoring industry also has some unwritten understanding of high definition. For example, the high-definition products we talk about on many occasions are actually products with a resolution of D1 or 4CIF . So what exactly is the concept of " high definition " in the video surveillance industry ? What is really " HD " ?
Let's first look at the definition of high definition in digital TV technology.
Digital TV is mainly divided into standard definition television and high definition television. Standard definition television ( SDTV ) refers to a digital television system with an image quality equivalent to the current conventional analog color television system, such as PAL , with a resolution of about 500 TV lines and a bit rate of about 5Mbps ; high-definition television ( HDTV ) Refers to a digital television system with horizontal and vertical resolution approximately twice that of current analog color television systems, with an aspect ratio of 16 : 9 , with a resolution of approximately 800 TV lines or higher and a bit rate of approximately 20Mbps .
In ITU-R Recommendation BT.1201, ITU proposed several standards for ultra high definition images ( HRI ). The basic element is that the minimum resolution of the image is 1920x1080 . HRI is divided into four levels, including HRI0 , HRI1 , HRI2 and HRI3 with resolutions of 1920x1080 , 3840x2160 , 5760x3240 , and 7580x4320 respectively .
According to the above definition, corresponding to video surveillance, the analog-digital mixed-monitoring of analog cameras can reach the highest standard definition. If digitally processed, the highest resolution can reach 4CIF or D1 resolution, about 400,000 pixels. Between 300 and 500 lines; IP surveillance using high-definition network cameras , if the definition of 800 TV lines is to be achieved , then the resolution of the network cameras must reach at least the standard of 1280x720 , about 900,000 pixels, which is two of the analog-digital mixed monitoring If you use a 2 -megapixel network camera, you can meet the requirements of ultra-high-definition images. A network camera with an aspect ratio of 16 : 9 corresponds to a resolution of 1920x1080 and a network camera with an aspect ratio of 4 : 3 . The resolution is 1600x1200 .