The HDMI 2.0 interface was cancelled? I am confused

If you have recently followed the monitor, graphics card, or game console market, you must have heard of HDMI 2.1. It is a new connection interface standard widely adopted on new graphics cards, monitors, game consoles and other devices; it allows support for improved bandwidth, resolution, refresh rate and functions.

When you hear HDMI 2.1, what do you think of?

Regardless of technical aspects and specifications, in the display (monitor and TV) market, the HDMI 2.1 terminology has been associated with several key functions and features in most people's minds. This is mainly driven by the game console market, where Sony PS5 and Microsoft Xbox Series X|S use HDMI 2.1 to support their latest features. HDMI 2.1 is also appearing as an alternative to DisplayPort in the PC graphics field, but it is indeed the game console market. This term has attracted mainstream attention and set expectations for most people. These functions and features cannot be achieved by older HDMI standards such as v2.0, or at least cannot be achieved in a more mainstream way supported by v2.1. They include:

Supports much higher bandwidth than the old generation;Support higher resolutions-including 4K and even up to 8K;Support 4K and 120Hz high refresh rate combination (including 10-bit, HDR and no color compression);Variable refresh rate (VRR) supported;ALLM (Automatic Low Latency Mode) supported.

Therefore, these are all the content that most people might want HDMI 2.1 displays to support, and we think it’s fair to say that these are the benefits they expect when buying HDMI 2.1-labeled displays. Sadly, as you will read later, it is far from simple.

Description of newly supported features

(1) Bandwidth, resolution and refresh rate

To get the most important 4K 120Hz support (including uncompressed 10-bit color), you need a higher bandwidth than HDMI 2.0. We will ignore resolutions other than 4K for the time being, because they are not really available in the display market anyway, and the current focus is 4K.

The standard HDMI 2.1 can support "FRL" (Fixed Rate Link) signals. As HDMI.org explains on its website: "FRL stands for fixed rate link, which is a signaling technology supported in the HDMI 2.1 specification. FRL is the realization of higher uncompressed resolutions (such as resolutions above 4k60). ) And necessary for ultra-high-speed bandwidth up to 48Gbps. FRL replaces the older TMDS (Transmission Minimized Differential Signaling) signaling method used on the HDMI 2.0 standard to provide a maximum 18Gbps transmission bandwidth on this interface. TMDS supports 4K 60Hz and 8-bit color depth, but it is far from enough to support 4K 120Hz 10-bit uncompressed color. Newer FRL signaling increases the port bandwidth to a maximum of 48Gbps. Due to the additional visual lossless compression, the HDMI 2.1 standard also adds Display stream compression (v1.2) support, allowing higher resolution.

As explained by HDMI.org on its website, the HDMI 2.1 specification still needs to support TMDS for backward compatibility to seamlessly support billions of HDMI devices using TMDS, but you need to remember that in order to support such things as Need higher bandwidth 4K 120Hz, also need to support FRL. All in all-TMDS signaling will support the features of HDMI 2.0 generation devices, and the updated FRL will support the higher bandwidth, resolution and refresh rate that most people associate with HDMI 2.1.

(2) Variable refresh rate (VRR)

More specifically, "HDMI-VRR" is a technology that can be built into HDMI 2.1, allowing variable frame rates that are compatible with graphics cards and modern game consoles. VRR can be used to reduce tearing and stuttering in games with different frame rates.

(3) Automatic Low Latency Mode (ALLM)

Automatic low-latency mode is a feature that allows the monitor to detect game input like a console, and then automatically switch to a defined mode that the monitor manufacturer has optimized for this purpose. Usually this means automatically switching to the "gaming" preset mode, where the input delay has been reduced and many of the normal "movie" enhancements are disabled.

In the TV market, if you buy a monitor with HDMI 2.1, you might expect and hope it supports ALLM to achieve this. The following table is provided by HDMI Licensing Administrator, Inc. and shows a complete list of new features related to HDMI 2.1. The monitor that prompted this investigation came from a manufacturer. At the bottom of their product page, they listed content containing 2 HDMI 2.1 ports: However, at the bottom of the page hidden in the terms and conditions, they went on to say the following (translation):

"Due to the subdivision of the HDMI certification standard, HDMI 2.1 is divided into TMDS (the bandwidth is equivalent to the original HDMI 2.0 and FRL protocol). The HDMI 2.1 interface of this product supports the TMDS protocol, and the maximum supported resolution is 1920×1080. The refresh rate is 240Hz."

This is a wake-up call for us, because they seem to be promoting a device with only HDMI 2.0 functionality, and the device is named after the new HDMI 2.1 name. It even specifically stated that it only uses TMDS in v2.0 instead of FRL.

What does HDMI 2.1 certification actually require? It doesn't look like a lot...

We have introduced the functions and features that we believe consumers generally expect when they see HDMI 2.1 advertisements. If you delve into the details of HDMI 2.1, you may be surprised to find that none of these things are actually necessary! We contacted the “HDMI License Manager” HDMI.org to ask some questions about this new standard. Here is what we were told: HDMI 2.0 no longer exists, and the device should not claim to be v2.0 compliant, because it is no longer reference.

The features of HDMI 2.0 are now a subset of 2.1

All new functions and features related to HDMI 2.1 are optional (including FRL, higher bandwidth, VRR, ALLM, and everything else). If the device claims to be compliant with 2.1, then they also need to explain which features the device supports . Therefore, according to what they told us, this means that theoretically all devices with HDMI 2.x connections should now be marked as HDMI 2.1, even if they may eventually only provide the feature generation of the old version of HDMI 2.0.

With the HDMI 2.0 certification now discontinued, these are basically 2.0 devices hidden under the 2.1 replacement mask. They don't have to provide any new features, but it looks like they should still be marked as 2.1.

When a term has a specific meaning in the market, it should convey these expectations. At least one baseline should be defined for certification. HDMI.org’s response is that while everything is okay-or rather should be marked as HDMI 2.1, manufacturers must also list the supported features to meet their certification standards.

According to the definition of the HDMI licensing administrator, the manufacturer’s advertisement on its 24.5-inch 1080p 240Hz monitor is actually correct. After all, it is not a "fake HDMI 2.1". These ports have absolutely no new features other than 2.0, but what they advertise to consumers is 2.1, which is misleading in my opinion.

If a screen with 4K resolution and 120Hz+ refresh rate does this, it will of course become more confusing and misleading. If it only has HDMI 2.0 type ports and bandwidth, it can still support 4K 120Hz, but it must have 8-bit color depth and 4:2:0 chroma sub-sampling to adapt to the old TMDS bandwidth.

What if they don't? What if they just list 4K 120Hz via HDMI and call it HDMI 2.1 (as the HDMI organization says)? In this case, you might expect full-color support. They will list the supported content, but will not point out the unsupported content, because they obviously don’t need it.

In my opinion, the mess seems to be waiting to happen. If manufacturers provide new HDMI 2.1 features, that would be great, I believe they will definitely want to promote these features. Will ordinary consumers realize that features not listed mean they are not supported, or will they assume that because it is HDMI 2.1, it can be completely compatible with other HDMI 2.1 devices (such as game consoles) that list something? compatible? ?

Requirements for manufacturers

Interestingly, what we currently see on the market seems to run counter to the guidelines detailed to us by HDMI.org. Displays that support HDMI 2.0 are still marked as HDMI 2.0 and sold on the market. In fact, we think this is a good thing. In almost all cases, all products sold as HDMI 2.1 include at least high-bandwidth support other than HDMI 2.0, and most also provide additional functions such as VRR. We prefer to see the continued use of the HDMI 2.0 label, rather than "abusing" the HDMI 2.1 name on a large scale.

Ideally, this will continue, but the HDMI.org guide seems to be the opposite. We believe that the absolute baseline requirement for a display to be listed as 2.1 should be to support FRL to allow new bandwidth beyond 2.0. The most important upgrade of this new 2.1 standard is to increase the bandwidth above 18Gbps, as well as support for higher resolution and refresh rate.

All the HDMI 2.1 advertising displays we have seen so far provide this improvement. If a display can only perform the old TMDS signal HDMI 2.0 bandwidth, it would be much cleaner to mark it as HDMI 2.0. If VRR, ALLM and other functions are also mandatory under the 2.1 certification, we really like it because it will make consumers more aware.

However, if we want to classify every HDMI 2.x device under the 2.1 banner, we will ask display manufacturers to be very clear on their product pages and specifications which features are supported, and equally important is not. Please do not hide everything under the HDMI 2.1 name, and do not fail to provide the features that consumers expect to see just because it is technically possible.

How should consumers know?

According to the HDMI.org guidelines, it seems inevitable that we will see more displays sold with hypothetical HDMI 2.1 connections from at least smaller manufacturers in the future. Perhaps disappointingly, the HDMI 2.0 name will be completely removed.

In my personal opinion, it would be much better if HDMI 2.1 had a clear set of requirements, and the term could only be used if all of these requirements were supported. If you want to have several layers of features to provide flexibility, that's great, you only need to have HDMI 2.0, 2.1, 2.2, 2.3 or any other features.

From the perspective of our content, we have tested and confirmed what features and functions the screen provides. Among them, HDMI 2.1 is used for advertising. We will pay more attention to this in all future news, reviews, etc.