HDMI 2.1 specification released – all details

hdmi 2.1 spec diagram

HDMI Forum has launched version 2.1 of the HDMI specification, incorporating support for resolutions of up to 10K and dynamic HDR formats. The specification is available now to all HDMI 2.0 adopters.

Announced back in January, the specification supports a range of higher video resolutions and refresh rates including 8K60 and 4K120, as well as resolutions up to 10K. Dynamic HDR formats are also supported, with bandwidth capability upped to 48Gbps.

The newly unveiled ‘Ultra High Speed’ HDMI cable offers 48Gbps bandwidth, ensuring features such as uncompressed 8K video with HDR are delivered. The cable incorporates low EMI (electro-magnetic interference) to reduce interference with nearby wireless devices. It is backwards compatible and can be used with the existing installed base of HDMI devices.

Developed by the HDMI Forum’s technical working group, version 2.1 of the HDMI specification is backward compatible with earlier versions of the specification.

Key features of the HDMI specification:

  • Higher video resolutions support a range of high resolutions and faster refresh rates including 8K60Hz and 4K120Hz for immersive viewing and fast-action detail. Resolutions up to 10K are also supported for commercial AV, industrial and specialty usages.


  • Dynamic HDR support ensures every moment of a video is displayed at its ideal values for depth, detail, brightness, contrast, and wider colour gamuts—on a scene-by-scene or a frame-by-frame basis.


  • The Ultra High Speed HDMI cable supports the 48G bandwidth for uncompressed HDMI 2.1 feature support. The cable also features very low EMI emission and is backwards compatible with earlier versions of the HDMI Specification and can be used with existing HDMI devices.


  • eARC (Enhanced Audio Return Channel) targets simplifying connectivity and supports the most advanced audio formats and highest audio quality. It ensures full compatibility between audio devices and upcoming HDMI 2.1 products.


  • Enhanced refresh rate features ensure an added level of seamless motion and transitions for gaming, movies and video – including:
    • Variable Refresh Rate (VRR) reduces or eliminates lag, stutter and frame tearing for more fluid and better detailed gameplay.
    • Quick Media Switching (QMS) for movies and video eliminates the delay that can result in blank screens before content is displayed.
    • Quick Frame Transport (QFT) reduces latency for smoother no-lag gaming, and real-time interactive virtual reality.
  • Auto Low Latency Mode (ALLM) allows the ideal latency setting to automatically be set allowing for smooth, lag-free, and uninterrupted viewing and interactivity.

The HDMI 2.1 Compliance Test Specification (CTS) will be officially be published in stages between Q1 and Q3 of 2018.