The HDMI Forum and HDMI Licensing Administrator have announced a new and upcoming standard for the high-definition multimedia interface (HDMI) called HDMI 2.1a. It will be introduced in next month’s Consumer Electronics Show (CES), and follows up on the already existing HDMI 2.1.
The upcoming standard adds one new feature, and is therefore rather incremental in nature. The latest standard is called Source-Based Tone Mapping or SBTM.
The latter, going by reports, appears to be a way for the HDMI Forum to urge device makers to standardise consumption of high dynamic range (HDR) content.
To work, SBTM mandates that the source of a piece of content -- be it a set-top box or a PC -- must optimise HDR content before relaying it through HDMI to an output medium -- a TV or a monitor. This optimisation, the HDMI Forum states, will apparently make HDR content more evident on more displays.
The reason behind this, reports say, is that most users who buy TVs and monitors often do not calibrate their displays to be compliant with HDR standards. As a result, with the new SBTM standard, displays will already get a pre-calibrated quality of visuals through HDMI 2.1a -- hence offering a more standardised HDR visual quality.
However, this is where problems seep in. A report by The Verge states that the HDMI Forum has failed to mandate how companies adapt to new HDMI standards. As a result, all new features of the latest HDMI standards are deemed as optional for all manufacturers. This means that even with SBTM, which seems like a practically useful new standard, manufacturers do not have to offer SBTM as a feature. This would hold true even when they brand their TV or monitor ports as HDMI 2.1a.
The SBTM feature on HDMI 2.1a joins other features of HDMI 2.1, such as variable refresh rate, automatic low latency calibration, 10K image resolution and up to 120Hz refresh rates that would be necessary for new generation gaming consoles to make the most of. However, in what is rather confusing, none of these features are compulsory for manufacturers to offer even when they brand their HDMI ports on board their TVs as HDMI 2.1 -- and now 2.1a.
As for adoption, it’s not clear as to when we might see the first televisions offering HDMI 2.1a. More details may come through when the standard is announced at CES 2022, including announcements from manufacturers about TVs and displays supporting SBTM.