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As display evolves, it has more and more interfaces. In this case, many people are getting more and more confused about what display interfaces are for. Even some friends who often pay attention to IT are same.

For this reason, it is necessary to conduct a comprehensive analysis of interface used by current display. At present, there are many interfaces involved in display, among which VGA, DVI, HDMI, USB, DP and so on are mainly used. Some of these interfaces are also divided into different types and versions. In this image analysis, it will be presented and analyzed in detail one by one.

VGA port

The VGA interface is a common interface that has been used from CRT era to present. It is an analog transmission interface with color difference, D-type port with 15 holes, which transmit different signals accordingly. In addition, VGA interface is also called D-Sub interface.

Features:

Theoretically, it can support 2048 x 1536 screen resolution;

Because VGA is an analog signal transmission, it is susceptible to interference, and signal conversion may result in signal loss.

At 1080P resolution, user can clearly feel image loss with naked eye;

It is recommended to use a display with a resolution lower than 1080P.

VGA is currently most widely used monitor interface, almost most low-cost monitors are equipped with a VGA interface, but also due to its obvious disadvantages, high resolution cannot provide required refresh rate, and only image input does not provide sound input prevents it from having space for playback on mid-range and high-end monitors.

DVI interface

DVI (Digital Visual Interface[1]), i.e. Digital Visual Interface. It was launched in 1999 by DDWG (Digital Display Working Group) jointly established by Silicon Image, Intel (Intel), Compaq (Compaq), IBM, HP (HP), NEC, Fujitsu (Fujitsu) and others. The company's interface is standard. The DVI interface is relatively complex, mainly divided into three types: DVI-A, DVI-D, and DVI-I. DVI-D and DVI-I are divided into single-channel and dual-channel.

DVI-A, analog interface used to switch to VGA, is obsolete.

The DVI-A digital interface is divided into two types: single-channel (18+1) and dual-channel (24+1). It does not adapt to VGA and you cannot use an adapter.

DVI-I is compatible with analog and digital interfaces, in fact, you can say that it is integration of A and D. It can be converted to VGA, but an adapter is required.

Features:

Can only transfer images, supports limited resolution;

Only supports 8-bit RGB signal transmission, and support for some displays with wider color gamuts is not ideal;

The interface is relatively large and inefficient, so it cannot be applied to devices such as ultrabooks.

Compatibility with devices is average, especially with flat screen TVs.

DVI transmits digital signals, and digital image information will be directly transmitted to display device without any conversion, thus reducing cumbersome digital-to-analog-to-digital conversion process and greatly saving time, so its faster speed effectively eliminates smearing. The phenomenon and use of DVI for data transmission, signal does not fade, color is purer and more realistic, and it is also widely used at present.

HDMI

In review articles, netizens often mention why this monitor does not have an HDMI interface? It seems that lack of an HDMI interface is now main drawback of monitor. Why is HDMI so popular? It can be said that HDMI is most common interface in our daily life, and it is widely used in home multimedia equipment.

In April 2002, seven companies, including Hitachi, Panasonic, Philips, Silicon Image, Sony, Thomson and Toshiba, jointly established HDMI High Definition Multimedia Interface Organization and began developing a new digital video/audio standard-compliant interface technology era of high definition. After more than half a year of preparation, HDMI officially released HDMI 1.0 standard on December 9, 2002, marking official entry of HDMI technology onto stage of history.

High Definition Multimedia Interface (HDMI) is a digital video/audio interface technology. This is a special digital interface suitable for image transmission. It can transmit audio and video signals at same time. speed 2.25 GB / s.

Features:

The latest HDMI1.4 standard can support 4Kx2K transmission over Ethernet, Audio Return Channel, support 3D functions, etc.;

Support for 4K resolution output, which improves basis for supporting modern 4KK TVs and monitors;

Support 3D function, which can meet signal transmission requirements of 3D TV display;

It can also support more than 30-bit color gamut, and can display most realistic and vivid colors according to different standards.

Display interface analysis

HDMI is a digital interface that provides best video quality because all analog connections (such as component video or S-video) are lossless when converting from analog to digital. This difference is especially noticeable at higher resolutions such as 1080p. Digital video will be sharper than component video, eliminating softness and blurring that is typical of component video. Small, high-contrast details, such as text, really bring out difference. In addition, there are many reasons why HDMI interface is widely used, which also expands HDMI interface of various sizes, mainly including Micro, mini HDMI interfaces, and standard HDMI interfaces.

DisplayPort (called DP):

The DP interface is successor to DVI. The DisplayPort interface and miniDP interface developed by Apple are now common. Compared to DVI, DP interface has greatly improved, there have been qualitative changes in bandwidth and configurability.

In May 2006, Video Electronics Standards Association (VESA) approved version 1.0 of standard and updated it to version 1.1 six months later to support HDCP. Version 2.0 is also planned to be released this year.

The longest external distance of DP interface can reach 15M, speed can reach 10.8Gbps, 2560x1600 resolution and 30/36bit color depth are supported.

It also allows transmission of audio and video signals over a common cable, supporting a variety of high-quality digital audio.

In addition to 4 main transmission channels, it also provides a powerful auxiliary channel with a bandwidth of 1 Mbps and a maximum delay of only 500 µs, which can perform various functions;

Apple's miniDP interface is more powerful, not only compact, but can support compatibility of various interfaces, just need to add an adapter.

Currently, in latest 1.3 DP interface standard, speed can reach 21.6Gbps, and resolution can directly support up to 4K resolution, which is mainly used in PC, so all current 4K monitors use DP. interface.

Comparison of DP and HDMI interfaces

HDMI Advantage: Many products support HDMI, and it is more common these days.

Disadvantage: Poor PC compatibility, unable to support 3 or 6 multi-screen output.

DP Advantage: Perfect PC support, support 3 to 6 screen output.

Disadvantages: Exit late, not mainstream.

In short, DP is stronger and more advanced in theory, but it came out late, its application is narrow, and it is biased towards PC.

USB and audio interface:

Nowadays, more and more monitors are equipped with a USB interface, and this is latest USB 3.0 interface. For most monitors, USB setting is only for monitor to have a USB hub function. The user can easily connect to computer via monitor's USB downstream interface by connecting it to host computer via USB upstream interface.

However, for some smart displays, USB configuration naturally matches USB interface on host computer.

Some monitors are directly equipped with an uplink interface that is dedicated exclusively to monitor's built-in speakers, while some have two uplink and downlink ports that can be used for output other than built-in speakers, such as HDMI. input and audio output.

The monitor may have display interfaces including HDMI, DVI, VGA, DP, etc., as well as additional interfaces such as USB, audio, and USB HUB. Through above introduction, I hope everyone can get a general understanding of monitor interface, interface advantages and disadvantages, use cases, etc.