HDMI, for the past ten years or so, has been the standard for video transmission. Whether it's your TV, PlayStation, monitor, laptop, set-top box, or even your camera, an HDMI cable (and port) is the one you use to transmit video from the source to the display. Now, just ahead of CES 2022, HDMI Forum has announced a new HDMI standard called HDMI 2.1a. So what are the new things that HDMI 2.1a brings and why should you care? Check all the details down below.
So, what's new in HDMI 2.1a?
HDMI 2.1a builds on the latest HDMI 2.1 standard and brings a couple of new features. One of the major new additions in the HDMI 2.1a standard is Source-Based Tone Mapping, or SBTM. SBTM is a new HDR feature that will offload some of the HDR processing from your TV to the video source, like your Blu-ray player or your gaming console. It is not a new HDR standard — it's not here to replace HDR10 or Dolby Vision. Instead, SBTM will only help TVs and streaming devices distribute the HDR processing workload among themselves for smoother content playback.
HDMI Forum says that it will be possible for set-top boxes, gaming console companies, and TV manufacturers to add support for the new SBTM feature through a firmware update “depending upon [the video source's] design.” However, given how slow companies are to adopt new HDMI standards, you'll most likely be able to enjoy the new standard when you buy a new TV.
Why should you care?
So, yes, why should you care about HDMI 2.1a? Let's see this with an example. Have you ever played an HDR movie or a TV show on Netflix on your smart TV? You must have noticed some hiccups when the video is just starting. This is because all of the HDR video content processing is done on TV right now. The video source, which may be your Amazon Fire TV or Google Chromecast, has no role in processing the HDR data. It just passes the raw video data to the TV, which then processes it and plays. However, most of the TVs out there don't have very powerful hardware which isn't able to decode the HDR content smoothly, and thus, the video lags.
With HDMI 2.1a, this HDR processing workload will be distributed between the video source and the TV. This will result in better and smoother HDR video playbacks.
HDMI standards, lately, have (kind of) been a mess. This is because most of the features that the HDMI Forum adds to the new standard — say the addition of 10K resolution or 120Hz refresh rates to HDMI 2.1 — are optional. Meaning, the manufacturers don't have to comply with all the HDMI 2.1 features for them to call their devices "HDMI 2.1 supported". Similarly, the SBTM feature of HDMI 2.1a is also optional. It will be an feature that manufacturers can support — but not something that they’re required to. This means that even if the devices don't support the new SBTM feature, manufacturers will still be able to call their devices "HDMI 2.1a supported".
All of these optional features make it harder for a consumer to distinguish between TVs that actually support all the HDMI 2.1 features and those that don't. As TFTCentral reports, most of the manufacturers aren’t following the HDMI licensing recommendations for HDMI port labeling. For now, companies label their ports as HDMI 2.0 which don't support the new features that have been added with HDMI 2.1. However, since "there is no HDMI 2.0 standard anymore: all new HDMI 2.0 ports should be lumped into the HDMI 2.1 branding, despite not using any of the new features included in the “new” 2.1 standard."
It's feared that the same thing will happen with HDMI 2.1a as well. Companies would start marketing their devices as "HDMI 2.1a" supported even if the ports don't support the new SBTM feature. So, it'll remain important to read the fine-prints of the TV boxes to know what feature it supports and what it doesn't — even though it was the whole point of introducing HDMI standards.