What are the four common video interfaces of LED display?
Jul 22, 2021
The common video interfaces of LED display include AV input interface, VGA input interface, DVI input interface and HDMI input interface. Four mainstream video interfaces. Here is an introduction to the four interfaces one by one.
1. AV input interface
AV interface (also known as RCA standard video input interface) is a relatively early interface, which is composed of red, white and yellow lines. The yellow line is the video transmission line, and the red and white line is responsible for the sound transmission of left and right channels. Generally, RAC lotus head is used for connection. AV interface realizes the transmission of video and audio separately, which avoids the degradation of image quality caused by the mixed interference of two kinds of signals. But because this kind of interface transmission is a kind of luminance (Y / C) mixed video signal, it needs further light color separation and chroma decoding to image, which will inevitably cause the loss of color signal, and ultimately affect the output image quality.
In a word, AV interface can separate audio and video transmission to avoid mutual interference. But there are still transmission losses, so the AV interface is basically abandoned for HD video playback.
2. VGA input interface
VGA interface adopts asymmetric distribution of 15pin connection mode. The working principle is that the image signal stored in digital format in the video memory is analog modulated into analog high frequency signal in RAMDAC (digital to analog converter), and then output to LED screen for imaging. Because VGA decomposes video signal into R, G, B primary color and HV line field signal for transmission, the loss in transmission is quite small. VGA interface has the advantages of no crosstalk, no circuit synthesis separation loss and so on.
3. DVI input interface
DVI interface is mainly used to connect with computer with independent graphics card to display RGB signal of computer. The DVI digital interface transmits all the contents in digital format. In the process of transmission, there is no interference signal, which ensures the transmission quality from the host to the LED screen, and can get a clearer image.
4. HDMI input interface
HDMI (high definition multimedia interface) is based on DVI technology. It is a fully digital image and sound transmission interface, which can transmit uncompressed audio and video signals. HDMI can provide 10Gbit / s data transmission bandwidth to meet the requirements of high-definition image quality. At the same time, HDMI interface does not need digital analog digital conversion, which can ensure high-quality video signal transmission. HDMI cable can transmit audio signal and can be used to avoid digital audio wiring.
In addition, among the input interfaces of LED display, there are S-Video, video color difference input interface, BNC interface, RS-232C serial port, etc., which are being replaced by HD interface.
To sum up, with people's higher and higher requirements for display screen image quality, analog transmission is being replaced by high-definition digital. It is believed that in the near future, 4K and other image quality will also be displayed on LED display.
