In our lives, whether it is a computer, a TV, or a projection device, etc., there is no need for a video output interface. Especially on a video card, there are usually 3 or more interfaces. Many people do not understand the difference. Think that if you have screen output, you can, in fact, it is not true for many monitors. Today, let's talk to you about the video interface.
The oldest interface - VGA
VGA Interface (Video Graphics Array)
The history of the VGA interface can be traced back to 1987. The blue plug is also the most recognizable interface. The VGA connector has 3 pins, 5 in each row, and 15 pins in total. The VGA interface uses analog. Signals, while using CRT monitors (commonly known as the heads of the brain) before, all use VGA interfaces, but they have almost been eliminated. Only a few projection devices or some instruments are still in use.
The VGA interface transmits analog signals and has weak anti-interference ability. At present, the display is basically a digital signal. The analog signal undergoes several conversions between signals, which may cause part of the signal to be lost, resulting in degradation of the picture quality. The main reason for elimination.
Interface with higher display usage - DVI
DVI Interface (Digital Video Interface)
With the rapid development of liquid crystal displays, the traditional VGA interface has been unable to meet, DVI interface was born, it can achieve long-distance, high-quality digital signal transmission, I believe that many people's monitors are still using DVI interface. Although white The plug is also very good resolution, but the specific specifications are still more complicated.
There are three kinds of DVI interfaces, namely DVI-I (Integrated), DVI-D (Digital), and DVI-A (Analog). DVI-I and DVI-D are also divided into 'single channel' and ' Dual channel' two types.
The DVI-A interface still transmits analog signals, so there is no essential difference between the VGA interface and the DVI interface. The DVI-I interface supports both analog and digital signal transmission. It is a transitional product; the DVI-D interface only supports digital signals. , It is also the most common DVI interface. Among them, the most popular is the dual-channel model, which has more bandwidth.
The obvious disadvantage of the DVI interface is that it does not support the transmission of audio signals, and the interface is bulky and therefore it is slowly being eliminated.
The current mainstream interface - HDMI
HDMI Interface (High Definition Multimedia Interface)
Compared with DVI interface, HDMI supports audio output and has higher bandwidth. It can be regarded as the most mainstream video output interface at present. Since the interface becomes smaller, it is also widely used in televisions, monitors, notebook computers and other devices. On the HDMI interface, although there is no DVI load on the specification, it has a different form.
The most common of these is the HDMI A Type, which has a maximum of 19 pins. The HDMI B Type can be thought of as a Class A dual channel version. It has 29 pins and can transmit double the amount of data, but it doesn't apply to any Among the products, HDMI C Type and HDMI D Type are reduced in size and are more widely used in portable products.
The most powerful interface—DP
Almost all of the current displays are equipped with a DP interface, which can be regarded as an upgraded version of the HDMI interface, but internal data transmission is completely different from that of DVI and HDMI, and it has a higher bandwidth. Thanks to its good performance. With advanced technology, the DP interface has gradually become an essential interface for high-end displays.
DP interface (DisplayPort)
The DP interface also has a derivative form - the Mini DP interface, which is a smaller-sized DP interface introduced by Apple.
Type-C interface
The USB Type-C interface itself does not support video output, but it has an alternative mode. It can be used to transfer other chips to achieve different functions. It actually uses the DP standard signal transmission. The advantage is that the display can be solved by a single line. Screen output and power supply problems.
The bandwidth of the wire is important
In the above, we repeatedly mentioned a word that is 'bandwidth'. Bandwidth is very important for video output lines. For some high resolution or high refresh rate displays, the bandwidth of the cable is insufficient and cannot be displayed. Corresponding video effects. In the above figure, with the refresh rate of 60Hz as the standard, we have listed the specifications that some common wires can support.
to sum up
Seeing this, I believe that you can basically understand the difference between different video transmission interfaces. In the future, we must pay attention to the specifications of different wires when we purchase wires. In fact, the simplest and most brutal way is to choose DP on the right!
