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Understand the computer video interface, you will understand after reading it.

Update:25 Aug 2020
Summary:

Some time ago, I just changed a monitor, and the monito […]

Some time ago, I just changed a monitor, and the monitor was equipped with all kinds of video cables. I only use one of them if I use it myself.

In fact, when you buy a computer, you will also see a variety of interfaces for monitors and graphics cards. So why are we still have so many computer video interfaces? What are the differences between these interfaces except for the different shapes?

Video interface diversity

In the history of our computer, there are many interfaces, and only the video interface we can often access is VGA, DVI, HDMI and DP interfaces, and so far, there are still many graphics cards still supporting the old-fashioned VGA, DVI interface.

The current public version of the graphics card will have HDMI and DP interfaces, but the general graphics card manufacturer will add a DVI interface on the graphics card, but at present our newly purchased display interface is complete with these three interfaces, VGA currently It was eliminated, because VGA transmits analog signals.

In addition to the different shapes, what are the big differences between these interfaces?

VGA interface

Display data line performance: DP>HDMI>DVI>VGA. Among them, VGA is an analog LCD MONITOR ARM  signal, which has been eliminated by the mainstream. This is why we can see the other three interfaces on the latest graphics card but can't see the VGA interface. DVI, HDMI and DP are digital signals. Mainstream.

However, many of our old-fashioned monitors are still VGA connectors, so we often use an HDMI or other interface to VGA interface adapter.

DVI interface

DVI is a high-definition interface, but without audio, that is, DVI video wiring only transmits picture graphics signals, but does not transmit audio signals.

However, the DVI interface also has many drawbacks: since it was originally designed for the PC side, it has reserved a lot of pins to support the simulation for poor compatibility with TV and only supports 8bit RGB signal transmission and compatibility considerations. The device causes the interface to be bulky.

At present, a better DVI interface can transmit 2K images, but it is basically the limit.

HDMI interface

HDMI can transmit high-definition graphics signals as well as audio signals. Generally speaking, the home will connect to the TV and it is highly resistant to interference.

The current highest HDMI2.1 standard supports 8k 60Hz and 4k 120Hz with a resolution of up to 10K. It also supports high dynamic range HDR and increases bandwidth to 48Gbps.

DP interface

The DP interface is also a high-definition digital display interface standard that can be connected to computers and monitors, as well as to computers and home theaters.

The DP interface can be understood as an enhanced version of HDMI, which is more powerful in terms of audio and video transmission.

In the current situation, there is not much difference in performance between DP and HDMI. If you use 3840*2160 resolution (4K), HDMI can only transmit 30 frames due to insufficient bandwidth, and DP has no problem.

Above we understand the differences between the various interfaces, but also the concept of color depth, bandwidth and so on.

In fact, the current mainstream is already HDMI and DP interfaces, but there is still a big difference between the two, especially in the bandwidth, in fact, our image signal transmission, the required bandwidth is also very high.

Let's take a look at the relationship between interface, bandwidth, resolution, and color depth.

Color depth (bit)

Let's first understand the color depth.

We can often see that some monitors for the color professional field are marked with 8bit/10bit panels. What does the bit mean? How do we understand it?

In fact, the bit represents the basic unit in the computer binary, and the binary information is composed of 0 and 1, and the same applies to the display.

I understand the computer video interface. I understand you after reading it.

Let's assume that I made a monitor that uses a 1bit panel, which means that the pixel of the display can only recognize 1 bit of information.

Then the information that this pixel can display is "1" or "0", then this pixel can display 2 (2^1) bit color, and each pixel is composed of RGB three colors, so finally our display Can show 2^1^3=8 colors.

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