What is HDMI 2.1? The new standard for HDMI connectors was formulated back in November 2017, but has not yet been rolled out to TV hardware for the general public. But when it became widespread, it marked a big step for the AV industry and home viewers who wanted to get the most out of their TV series, movies, radio shows and game consoles.
When High-Definition Multimedia Interface (HDMI) first came out, everyone was happy to never have to deal with bulky SCART connectors or those messy component video cables. Instead, HDMI delivers high-definition video in a connector only slightly larger than a standard USB plug. Over the years, the HDMI standard has evolved with the times, adding more features as the needs of televisions have changed.
HDMI 2.1 is the next step in this process.
The main feature of this step is support for 8K 60 fps content, but there are also some secondary features that lead to more powerful standards like support for variable refresh rates, dynamic HDR, and fast media switching, which should make it faster than ever to switch between devices connected to your TV.
Here's a rundown of all the changes that will come with this new standard:
Resolution and Refresh Rate
The new HDMI 2.1 cables will have faster refresh rates, including 8K resolution video at 60 frames per second and 4K resolution video at 120 frames per second, and that second feature will be the real selling point, at least initially.
We have significantly improved resolution and frame rate, said Jeff Parker, marketing director of HDMI Licensing, the HDMI specification licensing agency. He added that the Tokyo Olympics will drive the development of 8K TV content.
He said that NHK will promote 8K120 as an actual broadcast stream, and many consumer electronics manufacturers want to achieve this goal, so we are laying pipelines to provide flexibility to the industry.
Although HDMI 2.1 is what brings HDMI to the forefront, it can actually go further, supporting resolutions up to 10K at 120Hz, although it will be some time before this capability is supported on commercial devices.
Do I really need 8K?
You may wonder whether you need 8K-capable hardware and connectors. Maybe you don't need to: Most of the content you see on TVs is SDR or HD, and the industry is still getting used to the rush of 4K-capable TVs hitting the market. Isn't it too early?
But even if 8K TVs aren't on your radar, you can expect HDMI to be used in VR, Parker said.
"8K content has to keep up, but right now it's not all about linear content, it's also about VR," he said. "The goal of VR is very high resolution and very high frame rate, and one of the goals for VR applications that the industry talks about is 8K at 240Hz."
Actually this is not HDMI 2.1, but is achievable in the next spec, Parker said, and he thinks it might even be possible for some broadcasters to skip 4K transmissions entirely and go straight to 8K.
Game Mode VRR
The Game Mode VRR function of HDMI 2.1 is about real-time interaction. VRR stands for Variable Refresh Rate, which means less image lag, scan artifacts, and frame tearing, similar to what you get with FreeSync and GSync on PC platforms.
This is great news for gamers, as HDMI 2.1 will enable 3D graphics processors to render and display images in real time, which will result in a smoother gaming experience and greater detail.
This will find its greatest use in the VR world. "VRR means no lag and a more immersive experience that gaming requires, whether it's a traditional game or a movie 'on rails' VR experience," Parker said. "For VR to be truly immersive, fidelity needs to increase."
While not the end game, HDMI 2.1 will bring compelling VR experiences closer to us. "But it will have an immediate impact on all gaming applications," Parker added. "Whether it's 480p gaming or 8K, it doesn't matter - you'll get instant feedback and interaction over HDMI 2.1."
What is dynamic HDR?
Given the growing popularity of HDR, dynamic HDR brought by HDMI 2.1 may be the biggest news for home theater enthusiasts. Essentially, it means optimal depth, detail, brightness, contrast and wider color gamut values can be sent to your TV with greater nuance.
"Currently, HDR is done by taking an average of HDR across the entire movie, so while you still get some benefit, it doesn't apply perfectly to every scene," Parker said. "Dynamic HDR enables HDR metadata to be applied precisely on a frame-by-frame basis, or more realistically, on a scene-by-scene basis.
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Frame-by-frame HDR takes a lot of time, but scene-by-scene HDR is possible. Either way, HDR will give a greater effect.
What is EARC?
It’s not all about TVs; speakers, AV amplifiers and other audio equipment will also benefit from HDMI. 2.1, although this means upgrading all devices.
In previous generations, HDMI cables had an audio return channel (ARC), which meant audio could travel in both directions between the TV and the audio device. This essentially enables the display to send its own sound (perhaps from the built-in Netflix app) to the speakers or surround sound system, bypassing its own speakers.
Enhanced Audio Return Channel (eARC) is just a simple update to keep up with changes in audio codecs, specifically including the new object-based audio codecs - Dolby Atmos and DTS:X.
"eARC greatly increases bandwidth," Parker said. "Previously you were limited to two-channel PCM or traditional Dolby Digital or DTS audio, but with eARC, the reverse channel can now support higher bandwidth audio, including Dolby True HD, DTS HD, Dolby Atmos, DTS:X and other higher bandwidth object-based audio."
What is 48G cable?
This is about defining a new HDMI cable speed specification, a so-called 48G cable (currently just a working name) that provides 48Gb/s bandwidth to transmit uncompressed 8K HDR video over an HDMI 2.1 cable.
So why do we need 48G grade cables? "Because we are transmitting so much data now, we have increased from 18 Gb/s in HDMI 2.0 to 48Gb/s in HDMI 2.1." Parker said, "Now we have standard speed and high-speed HDMI cables, and 48G will be associated with it."
Same as above, each HDMI 2.1 cable must also pass compliance testing before it can be labeled accordingly. They are backward compatible with earlier versions of the HDMI specification and can be used with existing HDMI devices.
Which TVs are already equipped with HDMI 2.1?
From 2020, HDMI 2.1 will begin to enter the high-end series of today's major TV brands. Many of these products have only one HDMI 2.1 port (in addition to two or three HDMI 2.0 inputs), such as Samsung's new Q950TS 8K QLED TV this year. All of Samsung's 4K QLED TVs this year will come with an HDMI 2.1 port, which means you'll have some choices.
Other manufacturers are more generous with their support, with the LG CX OLED having four HDMI 2.1 ports, albeit 10-bit 4K/120Hz passthrough rather than full 12-bit. Considering the CX is only a 10-bit product, this won't really affect your screen image, though it's worth mentioning that LG has other TVs that support full 12-bit HDMI, such as the ZX OLED.
But in 2020, most 4K TVs will not be equipped with HDMI 2.1, and it may take several years to become standard. For example, Sony's new A8H OLED doesn't have an HDMI 2.1 port, although Sony's gaming division will release a 4K/120Hz-capable PS5 console later this year.
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