As we talked about display standards ranging from resolutions to display panels, refresh rates to HDR, an important aspect that helps bridge the display to your video source (Gaming Console, Computer, BluRay player) is the connecting video interface.
Video interfaces have varied over the time with the older analogue-based VGA, DVI and AV cable standards being replaced with the more modern and far more capable HDMI, DisplayPort, Thunderbolt and MHL standard.
Let us start by looking at the older VGA (Video Graphics Array) standard which is an analogue standard that uses two screws to secure the connector to the port. The maximum resolution supported by VGA is 2048×1536px (QXGA) at 85 Hz through its 15 pin connector.
VGA despite being present on almost all desktops and monitors have a few hardware gremlins like the pin connectors getting damaged and signal degradation with a change in cable length and gauge. Also, VGA is a display only connector and doesn’t support audio or data like HDMI or DisplayPort. With more compact modern standards in place that aim to replace multiple ports and connectors, VGA is all but obsolete.
DVI (Digital Visual Interface) is another connector designed to be locked via two screws just like the VGA connector, DVI though has a much larger physical size. DVI connectors have three different modes DVI-A (analogue only), DVI-D (digital only) or DVI-I (digital and analogue) and they can work with VGA and HDMI standards with adapters. Single link DVI supports resolutions up to 1920x1200 at 60 Hz while Dual-link DVI supports resolutions up to 2560×1600 at 60 Hz.
DVI is supported on Laptops, Desktops and Monitors, though it has begun to show its age like VGA and will soon be phased out. DVI has similar drawbacks to VGA with added ones being the much larger port and support for fewer colour spaces.
HDMI (High-Definition Multimedia Interface) is a modern connector that can transmit video, audio and data through a single cable. HDMI serves as a replacement for analogue standalone video connectors and tries to unify the video and audio cable into one. HDMI has seen many versions starting from 1.0, 1.1, 1.2, 1.3, 1.4 to the existing 2.0 and upcoming 2.1 standards.
Each version has aimed to improve the resolution, audio quality, add wider colour gamut support and add even more types of data transfer from 3D to Ethernet data. Let us look at the most popular HDMI standards in use today.
HDMI 2.0 which is widely in use today and found from laptops to televisions was launched in 2013. HDMI 2.0 has a maximum bandwidth of 18Gbits/s which enables it to transmit 4K at up to 60Hz at 24bit colour depth.
As we said before HDMI can take more than just video and supports 32 channel audio, dual video streams on the same screen, Rec 2020 colour space, up to 25fps of 3D video, wide 21:9 aspect ratio support, HE-AAC and DRA audio standards and additional CEC functions.
HDMI 2.0a was a minor revision of HDMI 2.0 which was released in 2015 and brought along HDR video support (static metadata only- like HDR10)
Released in 2016, HDMI 2.0b brought along support for HLG over the existing HDR10 support.
HDMI 2.1 was announced in 2017 and brings a lot of goodies for gaming monitors and high definition televisions. With its support for up to 4K at 120 Hz and 8K at 120 Hz, HDMI 2.1 is a must for all the cool new displays showcased at CES this year. HDMI 2.1 also adds a new cable category called Ultra High Speed which has a bandwidth of up to 48Gbit/s and is backwards compatible as well (though not at that speed).
HDMI 2.1 also brings support for Dynamic Metadata for HDR, DSC video formats, HFR, eARC audio formats like Dolby Atmos and DTS:X. Where HDMI 2,1 excels is that it uses the same connector as the HDMI 2.1 standard with the only real issue with HDMI (any version) being the connector not having any locking mechanism like VGA or DVI. To put it in basic words, HDMI 2.1 is the most featured packed Display standard currently available.
DisplayPort adds pretty much the same functionality like HDMI with the ability to send audio and video through one cable along with 3D support, multiple stream support and even data transfer support. DisplayPort, however, has its own merits too (over HDMI), like a lockable mechanism for the connector and has support for adapters that help to tailor it to other standards like VGA.
Launched in 2014, the DisplayPort 1.3 standard has a bandwidth of 32.4Gbit/s and supports multiple ultra-high resolutions. Resolutions support are 4K at 120 Hz with 24 bit/px, 5K at 60 Hz with 30-bit/px colour, 8K at 30 Hz with 24 bit/px colour.
DisplayPort can also power two display simultaneously. Resolutions supported for this are two 4K displays at 60 Hz, or up to four WQXGA (2560 × 1600) displays at 60 Hz with 24 bit/px colour.
DisplayPort 1.4 offers minor upgrades over 1.3 with support for static and dynamic metadata-based HDR, Display Stream Compression 1.2 support and Rec 2020 colour space support. DisplayPort 1.4 can support resolutions up to 8K at 60 Hz with 30 bit/px colour and HDR, 4K at 120 Hz with 30 bit/px colour and HDR and 4K at 60 Hz with 30 bit/px colour.
DisplayPort 1.4 too brings support for 8K resolutions like HDMI 2.1 albeit at only 60Hz. While most of us will never feel the need for an 8K monitor or television, there are tasks which need such high resolution from video editing to image editing and more.
MHL or Mobile High-Definition Link is a type of display connector that is used on mobile devices like smartphones, tablets and laptops. They act like a smaller version of HDMI cable and used the micro USB connector to save space in the small devices.
Introduced in 2013, MHL 3 supported output of 4K UHD at 30Hz and a maximum bandwidth of 6Gbit/s. Power delivery was also supported through that port limited to 5V at 2A (10W). For audio, MHL 3 has support for Dolby TrueHD and DTS-HD Master Audio.
superMHL 1.0 debuted in 2015 and brought along support for much higher resolution outputs keeping modern displays in mind. This standard can transmit up to 8K at 120Hz with HDR, Rec 2020 and 48-bit colour. Audio formats supported are Dolby Atmos and DTS:X. Being a newer standard, SuperMHL uses the more recent USB Type C port with support for power up to 40W (20V x 2A).
Despite their benefits, MHL has remained largely unused with only a few Samsung phones having support for them.
Thunderbolt 3.0 is the latest version of Thunderbolt, a standard that uses the USB Type C connector and aims to unify all the standards from display, video, data, graphics and power. That is why a single Thunderbolt port supports USB 3.1, PCIe 3.0, HDMI 2.0, USB Power Delivery and DisplayPort 1.2 standards.
When it comes to video, Thunderbolt 3.0 can output video to two 4K monitors at 60 Hz or a single external 4K display at 120 Hz or a 5K display at 60 Hz. It also allows daisy-chaining making multiple-device connections more streamlined.
Thunderbolt, due to its versatility and compact size is quickly becoming the defacto standard in laptops and desktops.
Verdict and Summary
Display standards, like most other standards we have touched upon, are in a state of constant change. What worked a few years back maybe a bottleneck for technology launching in the future. This is exactly what happened to VGA and DVI as in the 4K world of 2019, they similar cannot handle all the data that a computer of today has to crunch.
HDMI 2.1 and DisplayPort 1.4 are standards that are in tune with the technology being showcased today. From ultra-high resolution 8K displays to high refresh rates up to 240Hz, these two standards can help sustain the loads that these tasks can put on a display standard.
MHL meanwhile is a standard that should have gained traction with smartphones but it is left ignored by a huge section of the smartphone market. Unless it can bring along something revolutionary like Thunderbolt 3.0 which covers all bases from Data (USB 3.1), Display and Audio (HDMI 2.0 and DisplayPort 1.2), Graphics (PCIe 3.0) and Power (USB PD 100W), MHL has tough competition from Thunderbolt which is slowly trying to be the gold standard across the board.
Make sure to keep checking this space for more informative articles on technical standards around us.