It turns out that “HDMI 2.1” ports do not need to support HDMI 2.1 functionality.


Enlarge / Newer game consoles like the Xbox Series X and S support additional features on HDMI 2.1 displays, but HDMI 2.1 can mean different things depending on the product you buy.

If you use high-end 8K TV gear or have one of the latest Xbox or PlayStation consoles, you may be familiar with HDMI 2.1. The latest version of the ubiquitous display specification adds variable refresh rate support, lowers latency, and delivers a significant increase in bandwidth that enables higher resolutions, higher refresh rates, and greater color depth. At least he can support these things.

As it turns out, TV and monitor manufacturers don’t actually need to support these renowned HDMI 2.1 features to claim HDMI 2.1 compliance. This is the essence of a TFTCentral report, which underlines that the HDMI 2.1 specification replace the HDMI 2.0 specification rather than just upgrading it. So any manufacturer that supports HDMI 2.0 level functionality technically supports “HDMI 2.1” because the HDMI 2.0 specification no longer exists. And the features we think of when we talk about HDMI 2.1, including Fixed Rate Link Signaling (FRL), Variable Refresh Rate (VRR) support, Automatic Low Latency (ALLM), and Enhanced Audio Return Channel (eARC) – are technically optional.

“Products can no longer be certified for 2.0 only for 2.1, and 2.1 features are also optional to implement, so popular features like 4k120, ALLM, VRR are not required,” confirmed Brad Bramy, vice-president. president of marketing and operations for HDMI LA. in Ars. “Manufacturers couldn’t implement eARC, for example, and claim to be a 2.1 compatible device.”

Manufacturers claiming HDMI 2.1 support are required by the HDMI Adoption Agreement to clearly specify which HDMI 2.1 features are supported by their devices, although Bramy acknowledged that this can still be “confusing for consumers” and that individual manufacturers are ultimately responsible for letting people know what they get. This confusion is compounded by the fact that the terminology “HDMI 2.0” is still widely used, even though it has been technically obsolete.

“I think some older products certified under 2.0 just keep their… marketing intact,” Bramy said. “Some [manufacturers] Sadly thinks that even if they are certified under 2.1, they should still refer to 2.0 if they haven’t implemented 2.1 features, believing 2.0 to be a known feature set. It is also equally confusing to claim 2.1 compliance and still use the feature sets of 2.0 and not indicating the supported features. So there are several scenarios, and they can all be confusing. And that’s why manufacturers and resellers just need to state which features they support. I can say that it becomes clearer and clearer over time, but I’m not sure it’s a perfectly clear day. “

While this HDMI 2.1 situation is only getting around now, none of these facts are technically new – some Internet Archive Wayback Machine dig confirms that the HDMI 2.0 section was removed from the website between February 6 and February 13 from 2019. But there was a period when both specifications do coexist on the website, and the press release of November 2017 (PDF) announcing the HDMI 2.1 specification did not mention that HDMI 2.0 was going to be phased out. This is also not how the HDMI Forum handled the switch from HDMI 1.4 to HDMI 2.0, nor is it how most companies and developers handle it when they release a new version of something. thing.

There is precedent for this, although it’s not something everyone should want to emulate: the USB Implementers Forum has continually slapped new version numbers on older versions of the USB spec, something that started when “USB 3.0” became “USB 3.1 gen 1” many years ago. USB-IF has since elevated this practice to the art of performance, with absurd names like “USB 3.2 gen 2×2” and “USB 3.2 gen 1” (which is also USB 3.0).

This type of naming baffle has a clear advantage for hardware manufacturers, who can claim support for the most recent version of a specification even if they do not technically support all of the newer features. and the best of this specification. These manufacturers are well represented in the HDMI Forum and the USB-IF, both as members and like part of the leadership of the old organization. But for people who are just trying to buy things that support the features they need, this type of behavior continues to be confusing at best and intentionally misleading at worst. You can watch Dell, HP, Lenovo, and Acer product pages and see four different terms for the same type of port: “USB 3.0”, “SuperSpeed ​​USB 5 Gbps signaling rate”, “USB 3.2 gen 1” and “USB 3.1 gen 1”, respectively . All these elements are currently (or have been, at different times) perfectly valid means of designating this type of port.

The situation with HDMI 2.1 is not so bad yet, but if the HDMI Forum continues to introduce “new” version numbers that apply retroactively to older versions of the standard, we will end up in the same place. For now, you’ll just need to be extra careful when purchasing HDMI 2.1-labeled monitors and TVs if you’re interested in 8K, HDR, higher refresh rates, and other features specific to HDMI 2.1. Some companies are also responsible for specifying which products support all HDMI 2.1 features, as Microsoft has done with its “Xbox Game Features” Monitor Labels. But in the long run, I once again beg the standards bodies to just leave the version numbers mean something.


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