The HDMI interface is divided into four types: A, B, C, and D.

Among them, Type A is the most common. Flat-panel TVs or video devices generally provide this size of interface. Type A has 19 pins, a width of 13.9 millimeters, and a thickness of 4.45 millimeters. 99% of the devices that can be seen now have HDMI interfaces of this size.

Type B is very rare. It has 29 pins and a width of 21 millimeters. The transmission bandwidth is almost twice that of Type A. It is overly "powerful" in home applications and is now only used in some professional occasions.

Type C is designed for small devices. Its size is 10.42×2.4 millimeters, nearly one-third smaller than Type A. Its application range is very small.

Type D is the latest interface type. The size is further reduced. It adopts a double-row pin design. The size is similar to the miniUSB interface and is more suitable for portable and in-vehicle devices.

Although the HDMI interfaces are different, they all have the same function. Generally, for a qualified HDMI interface, the plugging life will not be less than 5,000 times. If plugged and unplugged every day, it can be used for 10 years. It should be said to be very durable. Another thing worth mentioning is that HDMI can be downward compatible with the DVI interface.

Through commercially available HDMI-DVI adapters, some older DVI devices can be connected. Because DVI also adopts the TMDS method, after the device is connected, it will be found that the DVI device does not have the CEC (consumer electronics control) function and cannot receive audio signals, but it basically does not affect the transmission of video signals (it may be necessary to adjust the gray level). Therefore, some monitors with only DVI interfaces can also be connected to HDMI devices.