HDMIin: the local video input is connected to the HD camera. DVI2: Local video input, generally used for double-stream training. HD-SDI: local video input is connected to a high-definition camera.

What is HD? Hd was first put forward in the field of radio and television, and the related standards were first formulated by the American Society of Motion Picture and Television Engineers (SMPTE) and other authoritative organizations. In the field of video surveillance, the standards of broadcasting and television are also widely used. "HD" is defined as 720p( 1280×720, line by line),1080i (1920×1080, interlaced) and/kloc-. HD is not an easy task for video surveillance. It involves many links of the monitoring system, from the front camera to the transmission, and then to the recording, storage and display equipment. In order to achieve the "high definition" index, we need to make corresponding adjustments. As long as one link fails to meet the requirements, it will fail to meet the "high definition" requirements of the system. Some manufacturers mainly aim at front-end camera equipment when promoting HD. It is true that the high-definition video effect first comes from the collection of high-definition information. If there is no front-end high-definition video acquisition, the high-definition effect of the back-end is impossible. However, it is not enough to just shoot high-definition images. These images are meaningful only when they reach storage devices and display devices through transmission devices. Taking transmission equipment as an example, the video wired transmission technology used in security monitoring system can be roughly divided into coaxial baseband transmission, coaxial modulation transmission, optical cable transmission, twisted pair transmission, IP network transmission and other transmission modes. These transmission modes have their own advantages and disadvantages, but at present, optical cable transmission and coaxial cable transmission are widely used.