HDMI Forum – an association that develops HDMI specs for video interconnects outlined its plans for HDMI 2.1. The specification of HDMI 2.1 has been finalized and giving a definitive view of what is in store for our video hardware.

HDMI 2.1 Transfer Rate

Concerning HDMI version, it seems to be a minor update, but the specs represent a significant step up from HDMI 2.0 making the HDMI 2.1 an Ultra High-Speed HDMI Cable which supports data transfer rates of 48Gb per second. This new cable is backward compatible with older HDMI specifications they are using same plugs and sockets but support substantially faster connections compared to 18Gb/s of HDMI 2.0 and 10.2Gb/s of HDMI 1.4.

What is it that you can do with such bandwidth?

More resolution with higher frame rates and more color depth. The New HDMI cable can support uncompressed 4K video at 120 frames per second with more top dynamic range color with 12 bits per channel. The framerate to 30fps and specs will support uncompressed 8K 12-bit video and use chroma subsampling, and it can hit 60fps at same resolution and color depth.

The HDMI 2.1 also allows video streams to go beyond 48Gb/s limit with its new feature called Display Stream Compression. This feature compresses video stream on the fly which helps notional data rates up to 128Gb/s for chroma subsampled 120fps 12bit HDR 8K video. It the 8K pixels is not enough for you there is some 10K formats support for 10,240×4,320 resolution specifically for commercial applications.


Beyond the raw data rates, HDMI 2.1 also brings some extra features. Gamers will be interested in Variable Refresh Rate—essentially a standardized version of Nvidia’s G-Sync and AMD’s Freesync (which is itself a patterned feature of the DisplayPort connection standard), which alters the refresh rate on the fly to match the speed at which frames are produced by the GPU—and Quick Frame Transport, which somehow reduces the latency of the HDMI connection.

High Dynamic Range (HDR)

For cinephiles, High Dynamic Range (HDR) allows the display to alter its contrast and brightness on a frame-by-frame basis and enhanced Audio Return Channel (eARC) ups audio support to uncompressed 7.1 and high bitrates positional audio systems such as Dolby Atmos and DTS:X.

Even with the spec complete, it’s going to be a while before we see HDMI 2.1 hardware on the market. Over the next nine months, the HDMI Forum will release compliance tests, and only then would we expect to see it become available in shipping products.

The range of new features means it’s in some ways a mixed bag; few of us will feel any pressing need to upgrade to 8K and 10K video—even for 4K, the content ecosystem is in its infancy—but specific audiences would see immediate benefits from VRR and QFT, given video cards and monitors that support them.