At present, the common PC monitor cables mainly include HDMI cable, DP cable, DVI cable, and VGA cable. Monitor cable performance ranking: DP>HDMI>DVI>VGA. VGA is an analog signal. DVI, HDMI, DP are digital signals, which are the current mainstream.

ⅠDP cable

DP (DisplayPort) is a high-definition digital display standard that connects computers and monitors, as well as computers and home theaters. DisplayPort has won the support of AMD, Intel, NVIDIA, Dell, HP, Lenovo, Philips, Samsung, aoc and other industry giants, and it is free to use. The DP cable can be understood as an enhanced version of the HDMI cable, which is more powerful in terms of audio and video transmission.

DP cable

This cable interface is designed to replace the traditional VGA, DVI, and FPD-Link (LVDS) interfaces. With active or passive adapters, the cable is backwards compatible with cables such as HDMI and DVI.

DisplayPort is the first display communication port to rely on packetized data transfer technology, which can be found in technologies such as Ethernet, USB and PCI Express. It can be used for both internal display connections as well as external display connections.

Unlike past standards that required fixed transmission of timer signals inside each differential pair of outputs, the DisplayPort protocol is based on small data packets called microtexts, which allow the timer signals to be embedded in the data stream. The advantage is that a higher resolution can be achieved with a smaller number of pins. The application of datagrams also allows the use of DisplayPort scalability, which means that over time, additional functionality can be added without significant changes to the physical communication port itself.

DP cable can be used to transmit both audio and video, each of which can be transmitted separately without the other. The video signal path can have 6 to 16 bits per color channel, and the audio path can have up to eight channels of 24-bit 192 kHz uncompressed PCM audio. A bi-directional, half-duplex auxiliary channel carries device management and device control data for the primary link, such as VESAEDID, MCCS, and DPMS standards. In addition, the communication port is capable of carrying bi-directional USB signals.

DisplayPort signals are not compatible with DVI or HDMI. However, dual-mode DisplayPorts are designed to carry single-link DVI or HDMI 1.2/1.4 protocols over this communication port, which needs to be implemented by using an external passive connector to select the desired signal and convert the electrical signal from LVDS to TMDS. Dual-mode DisplayPorts with passive connectors do not support VGA and dual-link DVI. These communication ports require an active connector to convert the desired output protocol and signal. The VGA connector can be powered using the DisplayPort connector, while the dual-link DVI connector may rely on an external power supply.

The DisplayPort connectors can have 1, 2, or 4 differential data pairs (lanes) on the main link. Each lane can have a raw code rate of 1.62, 2.7, or 5.4 Gbit/s on a self-timer running at 162, 270, or 540 MHz. The data is 8b/10b encoded, meaning that every 8 bits of the message are encoded into 10-bit symbols. Thus, the effective data transfer rate per channel after decoding is 1.296, 2.16, 4.32 Gbit/s (or 80% of the total).

Ⅱ HDMI cable

HDMI cable is capable of transmitting both high-definition graphics picture signals and audio signals, which are generally connected to the TV at home and are resistant to interference. It is worth mentioning that the interface of current car systems, such as car navigation, is also HDMI.

HDMI cable

HDMI is designed to replace older analog signal-to-video transmission interfaces such as SCART or RCA terminals. It supports all types of TV and computer video formats including SDTV, HDTV video footage, plus multi-channel digital audio.

Both HDMI and UDI, with the audio transmission function removed, inherit DVI's core technology "Transmission Minimized Differential Signal" (TMDS), which is still essentially an extension of DVI. The amount of data per pixel is 24 bits. The timing of the signal is extremely similar to VGA. The picture is sent in a line-by-line fashion, with a specific blanking time added after each line and frame is sent (similar to an analog scan line), without "Micro-Packet Architecture" of the data, and without updating only the two frames before and after the frame change. Each frame is retransmitted in its entirety at the time of the update. The specification was originally developed with a maximum pixel transfer rate of 165Mpx/sec, which is sufficient to support 1080p quality at 60 frames per second, or UXGA resolution (1600x1200). It was later expanded to 340Mpx/sec in the HDMI 1.3 specification to match possible future needs.

HDMI also supports uncompressed 8-channel digital audio transmission (sample rate 192kHz, data length 24bits/sample), as well as any compressed audio streams such as Dolby Digital or DTS, and also supports 8-channel 1bit DSD signals used by SACD. In addition, HDMI 1.3 specification adds support for ultra-high-data uncompressed audio streams such as Dolby TrueHD and DTS-HD.

The standard Type A HDMI connector has 19 pins, and a Type B connector has been defined to support higher resolution, but no manufacturer is using Type B. The Type B connector has 29 pins, allowing it to send extended video channels to cope with future high-definition demands such as WQSXGA (3200x2048).

The HDMI organization is sponsored by major consumer electronics manufacturers such as Hitachi, Panasonic, Quasar, Philips, Sony, Thomson RCA, Toshiba, Silicon Image, and Digital Content Protection, LLC, which provides copy-protection technology related to the HDMI interface. In addition, HDMI is also supported by major movie production companies such as 20th Century Fox, Warner Brothers, Disney, major consumer electronics manufacturers including Samsung Electronics, and several cable TV system operators.

To learn more about HDMI cables, please read this:  How much do you know about HDMI Cable?

Ⅲ DVI cable

DVI is a high-definition interface but does not carry audio, which means that DVI cables only transmit picture graphics signals, but not audio signals.

DVI cable

DVI is based on TMDS (Transition Minimized Differential Signaling) technology to transmit digital signals. TMDS uses an advanced coding algorithm to encode 8bit data (each base color signal in R, G, and B) into 10bit data (including line field synchronization information, clock information, data DE, error correction, etc.) by minimum conversion. After DC balancing, a differential signal is used to transmit data. It has better EMC performance compared with LVDS and TTL, and can realize long-distance and high-quality digital signal transmission with low-cost special cables. Digital Video Interface (DVI) is an international open interface standard that is widely used in PC, DVD, High Definition Television (HDTV), High Definition Projector, and other devices.

DVI cable has 3 types and 5 specifications, and the terminal interface size is 39.5mm x 15.13mm.

The 3 major categories include DVI-Analog (DVI-A) cables, DVI-Digital (DVI-D) cables, and DVI-Integrated (DVI-I) cables.

The five sizes include DVI-A (12+5), single connection DVI-D (18+1), dual connection DVI-D (24+1), single connection DVI-I (18+5), and dual connection DVI-I (24+5).

DVI cables are further divided into Single Link and Dual Link when transmitting digital signals. The transmission rate of Single Link DVI cable is only half of Dual Link, 165MHz/s, and the maximum resolution and refresh rate can only be supported up to 1920x1200, 60hz. As for the dual connection DVI cable, it supports up to 2560x1600, 60Hz mode, and can also support 1920x1080, 120Hz mode. LCD monitors must have a refresh rate of 120Hz to achieve 3D effects, so 3D programs that use DVI must use DVI cables with dual-connector DVI interfaces. In general, if the resolution is within 1920x1200, single and dual connection both output image quality is the same.

DVI-I supports digital/analog conversion interface types, so if the monitor has only one DVI interface, it will be paired with DVI-I that supports both digital/analog modes; if the monitor has both DVI and VGA interfaces, it will be paired with DVI-D.

Parameters of different types and specifications of DVI interfaces

Ⅳ VGA cable

VGA (Video Graphics Array) is a video transmission standard introduced by IBM in 1987 along with the PS/2 machine, with high resolution, fast display rate, rich colors, and other advantages. In the field of color monitors, VGA cables have been widely used. VGA cable supports hot-swapping, but it does not support audio transmission.

VGA cable

VGA cable interface is not only the standard interface for CRT display devices, but also for LCD liquid crystal display devices, with a wide range of applications.

With the development of the electronic industry and video image processing technology, VGA (video graphics array) as a standard display interface has been widely used in the field of video and computers. In image processing, if the traditional data transmission method is used to make the high-resolution image displayed on the monitor in real-time, the crystal frequency is generally required to reach more than 40MHz, and it is difficult for the traditional electronic circuit to reach this speed. If a special image processing chip is used, its design difficulty and high development cost become a bottleneck choice.

VGA cable interface is a D-type interface, a total of 15 pin holes on it, divided into three rows, five per row. In addition to the 2 NC (Not Connect) signals, 3 display data buses, and 5 GND signals, the more important ones are the 3 RGB color component signals and the 2 scan synchronization signals HSYNC and VSYNC pins. The VGA interface is the most widely used type of interface on graphics cards, and most graphics cards come with this interface. Some cards that do not have a VGA interface but have a DVI (Digital Visual Interface) interface can also be converted from DVI to VGA with a simple adapter, which is usually included with cards that do not have a VGA interface.

Most computers are connected to external display devices via an analog VGA cable. The display image information generated digitally inside the computer is transformed by the digital/analog converter in the graphics card into R, G, and B primary color signals and line and field synchronization signals, which are transmitted to the display device through the cable. For analog display devices, such as analog CRT monitors, the signal is sent directly to the corresponding processing circuit to drive and control the picture tube to generate images. For LCD, DLP, and other digital display devices, the display device needs to be equipped with the corresponding A/D (analog/digital) converter to convert the analog signal into a digital signal. The VGA cable is used in CRT monitors, but when used to connect to LCDs and other display devices, the image loss in the conversion process can cause a slight decrease in the display effect.