What is D1

As a closed-circuit television monitoring system for a long time, we all think that D1 is a hard disk recorder display, video, playback resolution, in fact not, D1 is the digital TV system display format standards, are divided into the following five kinds of specifications:

D1: 480i format (525i): 720 × 480 (horizontal 480 lines, interlaced), the same as the NTSC analog TV resolution, line frequency is 15.25kHz, equivalent to what we call 4CIF (720 × 576)

D2: 480P format (525p): 720 × 480 (480 lines of horizontal, progressive scan), is much clearer than D1 interlaced scanning, the same as progressive scan DVD specifications, line frequency is 31.5kHz D3: 1080i format (1125i) : 1920×1080 (1080 horizontal lines, interlaced), HD resolution is 1920×1080i/60Hz, line frequency is 33.75kHz D4:720p format (750p): 1280×720 (level) 720 lines, progressive scan), although the resolution is lower than the D3, but because progressive scan, more people on the market feel more clear than the 1080I (actual 540 line by line) visual effects. However, personal feeling, in the case of the maximum resolution of 1920 × 1080, D3 feels more clear than the D4, especially the text expression, the resolution is 1280 × 720p/60Hz, line frequency is 45kHz D5: 1080p format (1125p): 1920 × 1080 (1080 horizontal lines, progressive scan), the highest standard of civil high-definition video, resolution of 1920 × 1080P/60Hz, line frequency of 67.5KHZ. The D1 and D2 standards are the highest standards of our general analog television, and cannot be called high definition. The D3 1080i standard is the basic standard for high-definition television. It is compatible with the 720p format, and the D5 1080P is only a professional standard. Not civil class, the above given 60HZ is only the ideal field frequency, and its line frequency is 67.5KHZ, there is currently no such high-frequency TV, the actual field of 1080P in professional field only 24HZ, 25HZ and 30HZ.

The point to point out is that the D-terminal is a unique interface unique to Japan, domestic TV almost no such interface, the most is the color difference interface, and the color difference interface supports up to D4, theoretically certainly no HDMI (pure digital signal, The maximum resolution is up to 1080P), but there is usually no big difference in the resolution below 1920:1080.