On January 4th 2017, the HDMI Forum announced an update to the HDMI specification, pushing the revision to 2.1. Here is a rundown of the highlights that they have made public and what they may mean to consumer electronics. (The descriptions are taken verbatim from the press release linked to above.)

Higher Video Resolutions support a range of higher resolutions and faster refresh rates including 8K60Hz and 4K120Hz for immersive viewing and smooth fast-action detail.

HDMI 2.0b introduces support for [email protected], and the next logical step was to support higher refresh rates for 4K content. At the same time, they are announcing [email protected] support. The support for 8K is, I suppose, the next ‘logical’ step after full 4K. Let’s think about this for a second though. In terms of pixel density 4K is equivalent to 4x Full HD, but 8K is the equivalent of 4x 4K (or 16x Full HD)! My article on resolutions, screen sizes etc, may help put in perspective how ‘important’ 8K will be for the average home viewing situation. Hint – not at all. Still for situations where the viewer wants or needs to be very close to the screen, 8K could be an asset. Gaming, simulations and medical applications come to mind.

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

High Dynamic Range (HDR) is perhaps the most important development in video in recent years. In a nutshell, HDR expands the range of range of contrast and colour presented on screen, i.e. the difference between the darkest and the brightest possible values on screen at the same time becomes much larger, and the colour palette becomes richer. It arguably offers far more benefit to the viewer than the bump from Full HD to 4K by providing a richer image that more closely resembles how we see things in real life.

The way HDR is added to a video stream is by means of metadata. This way, the ‘raw’ video stream remains the same for all displays, and the displays that are HDR capable can read the metadata and render the content accordingly. Currently only static metadata is supported by the HDMI spec though, meaning that each piece of content only gets to ‘tell the display what to do’ once. Those settings are then applied to the entire video stream from start to finish. Using dynamic metadata means that every frame potentially contains its own metadata. The display can now change its settings as often as the content maker requires in order to produce the best possible image for each part of the video stream, down to the frame level.

48G cables enable up to 48Gbps bandwidth for uncompressed HDMI 2.1 feature support including 8K video with HDR. The cable is backwards compatible with earlier versions of the HDMI Specification and can be used with existing HDMI devices.

Higher frame rates and resolutions naturally require higher bandwidths, so a new generation of cables will be required. The HDMI 2.0b spec allows for a bandwidth of up to 18Gbps. This is a significant jump, and something to carefully consider when specifying cables for future projects.

HDMI matrices and extenders will have some serious catching up to do if they want to support the full feature set of the new spec. IP based solutions looking to provide uncompressed distribution of such signals will be able to extend their lead over conventional solutions here if they are able to handle the increased clock rates in their chipsets and make use of the new 25G and 50G ethernet standards for signal transport.

My prediction is that IP transport of HDMI for higher end systems will standardise and stick to 10GbE for the foreseeable future, and the manufacturers will offer specialty products for the edge cases where such extreme bandwidths are required, by making use of 25G and 50G technology.

eARC supports the most advanced audio formats such as object-based audio, and enables advanced audio signal control capabilities including device auto-detect.

The Audio Return Channel (ARC) is used to allow sources played natively on the display to send their audio back to an audio processor over an HDMI link. This upgrade will allow that link to support the most advanced multi-channel audio formats available

Game Mode VRR features variable refresh rate, which enables a 3D graphics processor to display the image at the moment it is rendered for more fluid and better detailed gameplay, and for reducing or eliminating lag, stutter, and frame tearing.

The refresh rate of a display is typically a set value (e.g. 60Hz), but the frame rate of games being played on a console or PC is not constant. It varies depending on how processor intensive the scene being rendered is. The conversion of this variable frame rate to a fixed refresh that the display can handle introduces a bit of lag, something gamers hate. This new feature will allow the refresh rate of the display to constantly match the frame rate of the game, meaning that each frame is displayed as it is rendered, minimising lag. This is bound to be a much appreciated feature for big screen gamers.

All in all some quite interesting developments here. The two most important new features in my opinion are the Dynamic HDR and the VRR modes. Both of these offer tangible benefits to end users. Equally as important is that content that benefits from both features is already out there. We’ll just have to wait and see when the first devices hit the shelves that implement the new spec though.


Originally published on January 15by Edwin Edelenbos on LinkedIn.

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