HDMI 2.1 supports 8K60Hz with HDR and object-based sound

hdmi 2.1 spec diagram

The HDMI Forum’s upcoming 2.1 spec looks set to rival the likes of Dolby Vision, with support for higher video resolutions and refresh rates.

It has been announced that HDMI 2.1-compatible displays will support a resolution as high as what HDMI Forum calls "10K" from a compatible source device and cable. More details on the components of 10K are yet to be announced, but could potentially mean a 16:9 multiple in line with the UHD versions of 4K and 8K or a wider version of 8K, as the company is also working on delivering “5K” resolution (potentially a wider version of 4K).

The HDMI Forum has also detailed higher frame rates, with each of 2.1's resolutions (4K, 5K, 8K, and 10K) able to refresh as much as 120 frames per second.

HDMI 2.1 will provide dynamic visual metadata as a standard. This lets content creators wipe the colour gamut and luminance defaults on screens at any time when rendering shifts to particularly bright or dark film scenes. Currently, luminance differentials on HDR-enabled TVs aren’t advanced enough to provide a difference, yet as screens develop to accommodate 2,000 nits and above.

HDMI 2.1's inclusion of dynamic metadata appears to allow any other video standard to take advantage of it, potentially leading to a revision of the HDR-10 spec in the future. HDMI 2.1 will natively support a wider colour gamut in the BT.2020 spectrum, along with colour depths as high as 10-, 12-, 14-, and a 16-bit.

The spec also incorporates object-based audio support via eARC (enhanced Audio Return Channel), allowing sound systems to process and play sounds based on where speakers are positioned in the room.

The specification will increase the requirement for cables, as HDMI 2.0's throughput of 18Gbps has been more than doubled for HDMI 2.1, allowing bandwidth up to 45 Gbps. New cables will be backward compatible with HDMI 1.4 and 2.0 devices, although older cables won't be forward-compatible with the latest spec.

The HDMI Forum states that the full specification behind HDMI 2.1 will be unveiled in Q2 or Q3 of 2017. As yet there is no clear indication when products will start to be introduced.