In modern display devices, there are many different interfaces and cables for transmitting video and audio signals. These interfaces and cables have their own characteristics and advantages and disadvantages, and are also suitable for different scenarios and needs. This article will introduce six common interfaces and cables: VGA cable, DVI cable, HDMI cable, DP cable, SDI cable and Thunderbolt 4 cable.
VGA (Video Graphics Array) is an analog signal interface that first appeared in the era of CRT (picture tube) monitors. VGA adopts a 15-pin pin structure to transmit component (RGB) and synchronous signals. The VGA interface is commonly found in old-fashioned graphics cards, notebooks, and projectors.
The advantage of the VGA interface is that it has good compatibility and can adapt to different resolutions. The disadvantage of the VGA interface is that the signal loss is large, and the image quality is blurred. Since VGA outputs and transmits analog signals, while computer graphics cards generate digital signals, and monitors also use digital signals, so the video interface using VGA is equivalent to undergoing a digital-to-analog conversion and an analog-to-digital conversion, resulting in signal degradation. .
The VGA interface has been gradually eliminated, and some new monitors no longer have a VGA interface. If you want to use the VGA interface, you need to buy an adapter or converter.
DVI (Digital Visual Interface) is a digital signal interface. Later, the white DVI interface appeared. When encountering different interfaces, we have to buy adapters to switch. Later, there were interfaces such as HDMI, and now there are DP and USB Type-C interfaces. So, with so many interfaces, what is the difference, and which one should we use?
There are many types of DVI interfaces, which can be divided into DVI-A (analog signal), DVI-D (digital signal) and DVI-I (analog + digital signal) according to the transmission signal. According to the bandwidth, it can be divided into single-channel (Single Link) and dual-channel (Dual Link). They have different connector shapes, and if the connectors do not match, they cannot be inserted and used.
The DVI interface transmits digital signals, which can transmit high-resolution video signals. DVI does not require conversion when connecting a computer graphics card and monitor, so there is no loss of signal. The advantage of the DVI interface is that the picture quality is clear and supports a high refresh rate. The disadvantage of the DVI interface is that it does not support audio transmission, and an additional audio cable needs to be connected; and with the popularity of new interfaces such as HDMI and DP, the DVI interface is gradually eliminated.
The maximum resolution and frequency supported by the DVI interface are shown in the table below:
HDMI (High Definition Multimedia Interface) is a high-definition multimedia interface, which is currently the most common cable, supported by TVs, computers, and projectors. The HDMI interface is a left-right symmetrical trapezoid, which can transmit pictures and audio at the same time.
The HDMI interface has undergone several upgrades and has now developed to the HDMI 2.1 standard, which supports 4K 120Hz and 8K 60Hz resolution and refresh rate, supports high dynamic range imaging (HDR), can be optimized for scenes or frame numbers, and is backward compatible HDMI 2.0, HDMI 1.4 and other old versions. The advantages of the HDMI interface are high popularity, good compatibility, support for audio transmission, and support for multiple protocols (such as EDID, HDCP, etc.). The disadvantage of the HDMI interface is that the length is limited (generally no more than 15 meters), does not support variable refresh rate technologies (such as FreeSync and G-Sync), and does not support daisy-chain connection of multiple monitors.
The maximum resolution and frequency supported by the HDMI interface are shown in the table below:
In addition, there are two derivative versions of the HDMI interface: Mini HDMI and Micro HDMI. These two interfaces are smaller and are mainly used in small devices, such as cameras and portable players, and there is no difference in performance.
DP (Display Port) is a digital signal interface and is a competitor of HDMI interface. On some graphics cards and monitors, in addition to the HDMI interface, it also has a DP interface. The DP interface is a rectangle with one corner missing, which can transmit images and audio at the same time.
The DP interface has also undergone multiple version upgrades. The latest DP 1.4 version can transmit 10bit 4K 120Hz video, and can also support 8K 60Hz video. DP1.4 is compatible with the USB Type-C interface, which can transmit data while outputting images, and DP1.4 supports daisy chain connection to multiple monitors. The advantages of the DP interface are high bandwidth, support for high resolution and high refresh rate, support for variable refresh rate technologies (such as FreeSync and G-Sync), support for HDR and daisy chain. The disadvantages of the DP interface are low popularity, incompatibility with old equipment, and limited length (generally no more than 3 meters).
The maximum resolution and frequency supported by the DP interface are shown in the table below:
The DP interface defines two connectors: Full Size (Full Size) and Mini DP (Mini). Both connectors are 20 pins, but the width of the Mini connector is about half of the full size. Mini DP connectors are mainly used on Apple computers.
SDI cable SDI (Serial Digital Interface) is a serial digital signal interface, mainly used in professional video equipment, such as cameras, monitors, switchers, etc. The SDI interface is circular and uses coaxial cables to transmit signals, which can support long-distance (up to 300 meters) high-definition video transmission.
There are many standards for SDI interface. According to the transmission rate and resolution, it can be divided into SD-SDI (standard definition), HD-SDI (high definition), 3G-SDI (3Gbps), 6G-SDI (6Gbps) and 12G-SDI (12Gbps). Their interfaces have the same shape, but are not compatible. The advantages of the SDI interface are high stability, strong anti-interference ability, support for high-definition video and audio transmission, and support for multiple protocols (such as EDH, ANC, etc.). The disadvantages of the SDI interface are high cost, low popularity, and not suitable for ordinary consumers.
The maximum resolution and frequency supported by the SDI interface are shown in the table below:
Thunderbolt 4 cable
Thunderbolt 4 (Thunderbolt 4) is a high-speed data transmission interface and an upgraded version of Thunderbolt 3. Thunderbolt 4 adopts the shape of USB Type-C, which can transmit data, video, audio and power at the same time. Thunderbolt 4 is compatible with protocols such as USB4, USB3.2, USB2.0, DisplayPort1.4a and PCIe3.0, and is also backward compatible with Thunderbolt 3 and Thunderbolt 2.
Thunderbolt 4 has the same speed as Thunderbolt 3 at 40Gbps, but Thunderbolt 4 improves in other ways. For example, Thunderbolt 4 supports dual 4K or single 8K display output, supports up to 100W power output, supports up to 10 meters of active cables or up to 2 meters of passive cables, and supports daisy chain connections of up to four Thunderbolt devices, Support security protection based on DMA (direct memory access), etc.
The advantages of Thunderbolt 4 are fast speed, powerful functions, good compatibility, and support for multiple protocols and devices. The disadvantage of Thunderbolt 4 is the high cost, and currently there are not many supported devices. Thunderbolt 4 is mainly suitable for professional users who need high-speed data transmission and multi-functional expansion, such as video editors, gamers, etc.
VGA cable, DVI cable, HDMI cable, DP cable, SDI cable and Thunderbolt 4 cable are six common display device connection cables. They have their own characteristics and advantages and disadvantages, and are also suitable for different scenarios and needs. Generally speaking, the following aspects should be considered when choosing a connecting line:
Which interfaces are supported by output devices and display devices
Resolution, refresh rate, color depth, HDR and other parameters of video and audio signals to be transmitted
The amount and speed of data that needs to be transferred
The number and distance of devices that need to be connected
Budget and value for money
According to different situations, you can choose the appropriate connecting line to achieve the best display effect. Here are some suggestions for common scenarios:
If you need to connect old-fashioned analog equipment, you can choose VGA cable or DVI-A cable
If you need to connect a high-definition TV or projector, you can choose HDMI cable or DP cable
If you need to connect professional video equipment, you can choose SDI cable
If you need to connect high-speed data transmission and multi-functional expansion equipment, you can choose Thunderbolt 4 cable