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HDMI 2.1: features, specs and news about the latest HDMI standard

What is HDMI 2.1? Everything you need to know

Most people probably don’t give much thought to their HDMI cables. “If it ain’t broke, don’t fix it”, as the old adage goes. Your current cables, connecting your Blu-ray player to your television, projector or soundbar work perfectly well, and that’s all that matters, right?

But soon, those existing HDMI cables may not work. That's because HDMI 2.1 is becoming more widespread, and your next TV, games console or media streamer might make use of the new standard and its increased bandwidth, higher frame rates and/or its higher resolutions.

So, while most people probably don't need to rip out their cables and rush down the shops for replacements just yet, some people might benefit from upgrading now, and others would be wise to apprise themselves of what this next-gen standard has in store...

What does HDMI 2.0 do?

HDMI 2.1: features, specs and news about the latest HDMI standard

Image source: HDMI.org

For those who don’t know the specs of their current cable, let’s get up to speed. HDMI 2.0 dates from 2013, and its main party-piece is being able to pass 4K content at 60fps (frames per second) – that’s video of 3840 x 2160 resolution, refreshed 60 times per second.

That high frame rate is most commonly utilised by video games that need to track lots of different objects such as whizzing bullets or speedy enemies – most films are made in 24fps, and television programmes are 25fps (or 30fps if the show is made in the USA).

A few years after the launch of HDMI 2.0, a small update, HDMI 2.0a, was launched to add support for HDR (High Dynamic Range). HDMI 2.0b followed shortly after with added support for the specific HLG (Hybrid Log Gamma) HDR format. Until now, that’s been the top standard for most consumers.

MORE: How to set up your TV and get the best picture

What does HDMI 2.1 do?

HDMI 2.1: features, specs and news about the latest HDMI standard

Image source: HDMI.org

Essentially, HDMI 2.1 has the capability to double-down on what HDMI 2.0 can manage. 2.1-standard connections will be able to easily outstrip the 4K limit, sending a maximum of 10K content at 120fps down the pipe.

All those extra pixels – six times that of standard 4K video – require greater bandwidth to send the information across. HDMI 2.1 cables are up to the task, with an upper limit of 48Gbps (Gigabits per second) rather than 18Gbps.

HDMI 2.1 supports Dynamic HDR at 4K/120fps and 8K/60fps. This allows the television to adjust its picture based on frame-by-frame information in the manner of Dolby Vision and HDR10+. Since dark landscapes might have different contrast requirements to that of brighter scenes, the ability to make instant adjustments should mean your movies and TV shows look their best.

The new standard has a few more improvements, too – it can, for instance, reduce the amount of time it takes to go from blank screen to content, thanks to a feature called QMS (Quick Media Switching).

And for game consoles and virtual reality headsets, HDMI 2.1’s VRR (Variable Refresh Rate) and QFT (Quick Frame Transport) features should result in a smoother experience.

Finally, HDMI 2.1 also supports eARC – an update to the ARC (Audio Return Channel) connection that will let you send DTS:X and Dolby Atmos soundtracks from your TV to your audio system in the highest possible quality, adding a higher degree of quality to an already very convenient feature.

It's worth noting that some HDMI 2.1 features, most commonly eARC, are available via some HDMI 2.0 devices and cables, but anything that requires very high bandwidth, most notably 4K/120fps and 8K/60fps, will require new hardware.

Do I have to buy a new television?

LG OLED65C1

LG's OLEDs have supported HDMI 2.1 since 2019 (Image credit: Future / Them, Amazon Prime)

It depends on what you’re looking to use HDMI 2.1 for. As mentioned, HDMI 2.1 isn't always required for a feature such as eARC. It depends on the product and if it's using compatible hardware that can accept the necessary firmware update. Likewise, there are TVs (and monitors) that will support VRR via HDMI 2.0 sockets, although those are fairly few and far between.

To get access to the full speed and feature set of HDMI 2.1, though, you are going to need a new TV. Thankfully, HDMI 2.1 models are becoming more common.

LG is undeniably the brand that led the way on HDMI 2.1 compatibility, having supported the standard on all of its OLEDs and its premium NanoCell TVs since 2019. Most of its sets, including the 2021 C1 OLED, have four HDMI 2.1 sockets.

Samsung, not one to take being outplayed by its compatriot company lying down, has also embraced HDMI 2.1, albeit a little more patchily. Almost all of its 2021 QLED TVs do have HDMI 2.1 sockets, but only the premium models that come with the One Connect box have four of them, with most models having just one.

Considering it's the company behind one of the only HDMI 2.1 sources currently in existence (the PS5), Sony is frustratingly behind its Korean rivals when it comes to supporting HDMI 2.1 on its TVs. Its first nominally HDMI 2.1-compatible models launched in 2020 but, despite having the required bandwidth, they don't support VRR out of the box. Even the brand-new (and brilliant) A90J is waiting for an as yet updated firmware update to add the feature.

Sony is still ahead of Panasonic and Philips, though, both of which are releasing their first HDMI 2.1-compatible TVs this year. Predictably, it will only be the premium models that will get HDMI 2.1 sockets, and only two each at that. Panasonic has confirmed that its models will also halve the vertical resolution displayed when handling 4K/120 and 4K/120 VRR at launch, with a firmware update promised to add full functionality. It's thought that Philips' models could take the same approach, although there's no official line from the company on that as yet.

In the US, there are also new models from Vizio and Hisense that have HDMI 2.1 sockets.

All told, it's something of a muddle, with even some of the HDMI 2.1-compatible TVs supporting only some of the features, supporting some features with caveats, and/or having only one or two HDMI 2.1 sockets. It's worth asking yourself whether you really need HDMI 2.1 now or whether it's better to wait a year or two when complete compatibility is more commonplace. 

If you are desperate to get on board immediately, the 2020 LG CX is the most affordable TV with four fully compliant HDMI 2.1 sockets.

MORE: HDMI ARC and HDMI eARC - everything you need to know

Do I have to buy new cables?

Ultra High Speed HDMI Cable certification

Image source: HDMI.org (Image credit: HDMI Licensing Administrator, Inc)

To take full advantage of any HDMI 2.1 sockets, you will need HDMI 2.1 cables. The good news is that the two most common HDMI 2.1 sources, the PS5 and Xbox Series X, come bundled with HDMI 2.1 cables, so you should be good to go if you buy one of those.

If you need an extra cable, or perhaps one that's longer or shorter than the one provided, you'll want to make sure it's fully HDMI 2.1 compliant. Being confident of that just got a fair bit easier, as the HDMI Forum, the organisation responsible for the HDMI spec, recently launched a certification program for HDMI 2.1 cables.

So-called Ultra High Speed HDMI Cables feature a QR code that can be scanned so that certification can be confirmed. There are plenty of cables out there that claim to support the HDMI 2.1 bandwidth of 48gbps, and many of them do, but it's worth getting a certified cable to be sure.

Of course, all HDMI 2.1 cables are backwards-compatible, so there's no harm buying one now even if you're yet to get an HDMI 2.1 source or TV.

MORE: 8K - everything you need to know

When HDMI 2.1 sources are available now?

As discussed above, there are now HDMI 2.1 TVs available from the likes of LG, Samsung, Sony, Vizio and Hisense, and models from Panasonic and Philips are imminent.

The two main HDMI 2.1 sources are the PS5 and Xbox Series X, with both of these next-gen consoles capable of outputting signals in 4K/120. In fact, they both already have games that take advantage, and those high frame rates can be particularly beneficial in fast-paced action games such as Call of Duty: Black Ops Cold War. The Xbox supports VRR, too, and the PS5 is said to be getting it soon via a firmware upgrade.

There are a number of HDMI 2.1 graphics cards available now, too, for those who do their gaming on PC rather than console.

Finally (for now), the new version of the Apple TV 4K also sports an HDMI 2.1 socket, although it currently doesn't make use of its extra bandwidth as it outputs at a maximum of 4K/60.

What about HDMI 2.1 AV receivers and soundbars?

Of course, if you want an HDMI 2.1 signal to make it from your source to your TV, any device in-between also has to be able to handle HDMI 2.1 signals. Thankfully, there are a few of those available now, too.

Denon's AVRs from the AVR-X2700H and up have at least one HDMI 2.1 input and output, and Yamaha's new models are HDMI 2.1 certified, too, although will require a firmware update to enable some features. It's also worth noting that both companies (and more besides) have had issues around support for 4K/120 via the Xbox Series X, but there are fixes in the works.

HDMI 2.1 soundbars are rarer, with the Sennheiser Ambeo and LG SP11RA the only examples that we've tested.

If you haven't got, and aren't in a position to, buy an HDMI 2.1 AVR or soundbar, you need not worry: just connect your HDMI 2.1 source directly to your HDMI 2.1 TV and use ARC/eARC (or even optical) to route the sound back from your TV to your audio device.

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