What is HDMI 2.1? Everything you need to know

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 the HDMI Forum – the organisation that manages updates and information about cables – is already looking towards the future, with HDMI 2.1. This new standard has increased bandwidth, supports higher frame rates, and can carry not just 4K but up to 10K video from your source to your screen.

So while you won’t have to rip out your cables and rush down the shops for replacements yet, you should be aware of what the future of television might well look like…

What does HDMI 2.0 do?

What does HDMI 2.0 do?

Image source: HDMI.org

For those that 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 routinely utilised by 4K video games that need to track lots of different objects like 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 later a small update, HDMI 2.0a, made the link between televisions and players capable of carrying HDR (High Dynamic Range) information as well, with HDMI 2.0b coming soon afterwards with support for HLG (Hybrid Log Gamma). 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?

Image source: HDMI.org

Image source: HDMI.org

Essentially, HDMI 2.1 has the capability to double-down on what HDMI 2.0a can manage. 2.1-standard cables 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 will also be able to support Dynamic HDR. This allows the television to adjust its picture based on frame-by-frame information in the manner Dolby Vision and HDR10+ operate. Since a dark landscape might have different contrast requirements to that of a brighter scene, 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 should, for instance, reduce the amount of time it takes to go from blank screen to content.

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

Finally, HDMI 2.1 is also ready to support eARC – an update to the ARC (Audio Return Channel) connection which will let you send DTS:X and Dolby Atmos soundtracks from your TV to your audio system, helping you get greater (and more convenient) audio excitement from compatible movies and shows.

MORE: HDR10 vs Dolby Vision: which is better?

Will I have to buy a new television?

Will I have to buy a new television for HDMI 2.1

Sharp's 70-inch 8K TV

Right now, you won’t. But you might have to in the future - it depends on what you’re looking to use HDMI 2.1 for. With regards to eARC, the HDMI Forum says it’s unclear whether your existing ARC connection will be able to work with it. That’s because it’s up to the manufacturers whether it will be available through a firmware update. We expect to hear more about this in due course.

In the FAQs on the Forum, it says “manufacturers can produce products that are compatible with both eARC and ARC. However, eARC is not defined to be backwards-compatible with ARC”.

Likewise, it’s possible Dynamic HDR will be available via a firmware update, but it looks like that’s down to the manufacturers too. Right now, we’ll just have to wait and see. But we expect televisions manufactured from 2019 onwards to start having HDMI 2.1 ports rather than HDMI 2.0.

In reality, the market is only just getting used to 4K, so we wouldn't be put off buying a new TV now because of what might arrive further down the line.

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

Will I have to buy new cables?

Will I have to buy new cables that support HDMI 2.1?

Image source: HDMI.org

Yes, although there’s no need to just yet. You’ll have to wait for the relevant hardware and software to become available before the need to join it together becomes an issue.

MORE: 8K - everything you need to know

When can we expect to see these updates?

Despite 8K TVs being previewed at both CES 2018 and IFA 2018 there was little mention of any supporting HDMI 2.1.

Where we have received confirmation of HDMI 2.1 support is regarding home cinema amplification. Denon's 13.2-channel flagship AV receiver, the AVC-X8500H, won't support HDMI 2.1 straight out of the box, but you have the option to add it through a 'charged upgrade service'. It will be a similar case with the Marantz AV8805, the brand's first 13-channel preamplifier.

Even the Samsung QE85Q900R, the first proper 8K TV we've tested, doesn't have any HDMI 2.1 inputs at the time of writing. Its HDMI inputs are housed in a separate box which Samsung claims it will swap out for a HDMI 2.1-equipped box at a later date. 

We'll keep our eyes and ears peeled for more HDMI 2.1 news in the coming months.

MORE: Best 4K HDR TVs