What are the four common video interfaces for LED display?
Nov 17, 2021
The common video interfaces of LED display screen mainly include AV input interface, VGA input interface, DVI input interface and HDMI input interface. Four mainstream video interfaces. Let's introduce these four interfaces one by one.
1. AV input interface
AV interface (also known as RCA standard video input interface) is an early interface, which is composed of red, white and yellow lines. The yellow line is the video transmission line, and the red and white are responsible for the sound transmission of the left and right channels. RAC lotus head is generally used for connection. The AV interface realizes the separate transmission of video and audio, avoiding the degradation of image quality caused by the mixed interference of two kinds of signals. However, because this kind of interface transmission is a video signal with brightness (Y / C), it needs further bright color separation and chroma decoding to image, which will inevitably lead to the loss of color signal and ultimately affect the output image quality.
In short, AV interface separates audio and video transmission to avoid mutual interference. However, there is still transmission loss, so at present, HD video playback basically gives up the AV interface.
2. VGA input interface
VGA interface adopts 15 pin connection mode with asymmetric distribution. Its working principle is that the image signal stored in digital format in video memory is analog modulated into analog high-frequency signal in RAMDAC (digital to analog converter), and then output to LED screen for imaging. Since VGA decomposes the video signal into R, G and B primary colors and HV line field signals for transmission, the loss in transmission is quite small. VGA interface has the advantages of no crosstalk, no circuit synthesis and separation loss.
3. DVI input interface
DVI interface is mainly used to connect with the computer with independent graphics card and display the RGB signal of the computer. DVI digital interface transmits all contents in digital format, and no interference signal is introduced in the transmission process, which ensures the transmission quality from the host to the LED screen and can get clearer images.
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 audio-visual signal transmission. HDMI cable can transmit audio signals and can be used to eliminate digital audio wiring.
In addition, among the input interfaces of LED display screen, there are S-Video, video color difference input interface, BNC interface, RS-232C serial port and other categories, which are being replaced by HD interface.
To sum up, with people's higher and higher requirements for the image quality of the display screen, analog transmission is being replaced by high-definition digital. It is believed that 4K and other image quality will also be displayed on the LED display screen in the near future.
