Editor’s Pick: HDMI 2.1...

...ain’t what it used to be

HOORAY for HDMI, the friendliest of display interfaces. Who needs anything else, especially now HDMI 2.1 supports both 4K@120Hz and 8K@60Hz? Well, you might if you want even faster refresh at 4K or daisy-chaining. And that might not be an entirely unrealistic expectation when AMD and Nvidia’s nextgen GPUs arrive later in 2022. Rumors suggest an even bigger step forward in performance than last time around. 200Hz-plus gaming at 4K? Don’t rule it out.

But I digress. There’s no question HDMI 2.1 is a good thing for PC users. As well as supporting lots of pixels and high refresh rates, it’s also adaptive-sync capable and includes support for low-latency display connections. This is enabling a new generation of HDTVs that play nicely with the PC—if you have an HDMI 2.1 graphics card. Which you won’t, unless you have either an Nvidia GeForce RTX 30 series or an AMD Radeon RX 6000 series.

Still, as HDMI 2.1 graphics cards eventually become the norm, PC users will have the option of a wide range of HDMI TVs, which deliver more bang for your buck than PC monitors. Sure, many are too big for ergonomic PC use, but a new class of HDMI 2.1 4K monitors designed for the latest games consoles and marketed at a lower price than a comparable PC monitor courtesy of HDMI 2.1 is incoming, too. A 32inch 4K@120Hz HDMI 2.1 monitor? Sign me up, please.

So, it’s all gravy when it comes to HDMI 2.1, then? Not quite. So far, HDMI 2.1 has been associated most importantly with the ability to support 4K@120Hz with full 10-bit uncompressed color. That’s courtesy of a maximum bandwidth of 48Gbps. Now, it’s true that not all displays and indeed output devices with HDMI 2.1 support have thus far supported the full 48Gbps. At launch, the Sony PlayStation 5 was capped at 32Mbps and the Xbox Series X at 40Gbps. In the case of the PS5, that means color fidelity at 4K@120Hz has to be reduced.

Anyway, the point is that you have to be careful not to make too many assumptions about HDMI 2.1. The devil is in the detail. Sadly, that’s just about to get a whole lot worse. It turns out, according to the HDMI Licensing Administrator, that HDMI 2.0 no longer exists. Its features are now a subset of HDMI 2.1. But here’s the kicker. The HDMI Licensing Administrator says that “all the new capabilities and features associated with HDMI 2.1 are optional. This includes FRL, the higher bandwidths, VRR, ALLM, and everything else.”

In other words, it is now possible to buy an HDMI 2.1 display that can’t do 4K@120Hz, adaptive refresh, or auto low latency. HDMI 2.1 no longer guarantees any of that stuff. It’s a bizarre decision that’s not only guaranteed to confuse consumers but also encourage display makers to cynically recertify what were once HDMI 2.0 displays as HDMI 2.1 compliant. Because they will be.

Of course, these standards bodies have form. The USB Implementers Forum did unspeakable things when they folded USB 3.0 and 3.1 into USB 3.2, leaving the latter as a broad church with little meaning and supporting anything from 5Gbps to 20Gbps. Before we had USB 3.0, USB 3.1 and USB 3.2, now we have USB 3.2 Gen 1, USB 3.2 Gen 2 and USB 3.2 Gen 2x2. How anyone thinks this is progress defies belief. The same goes for the changes to HDMI 2.1 nomenclature. It’s hard to see the benefit. Whatever, you have been warned. HDMI 2.1 ain’t what it used to be.