The new HDMI 2.1 standard for video and audio transmission is combined with enhanced features and support for higher resolutions, color depths and frequencies. But this may not always be the case. Devices or accessories may carry the HDMI 2.1 logo, but in fact they only support the eight-year-old HDMI 2.0 interface. TFT Central reported an interesting problem.
He came across it by chance while searching for the specifications of a new gaming monitor from Xiaomi. It comes with a pair of HDMI 2.1, although it won’t even need a newer interface. So TFT Central contacted HDMI LA, which licenses the technology of the same name, to find out if Xiaomi had mistakenly provided false information. She did not say, was the answer.
The organization said it no longer grants a license to HDMI 2.0. It now starts with a subset of HDMI 2.1 and all additional features are optional only. This means that the product can carry the HDMI 2.1 logo, although it is technically equivalent to the older generation. And the user will find out if it also supports the new features from a more detailed description.
Reminiscent of the constant rebranding of USB, USB 3.0, USB 3.1 Gen 1 and USB 3.2 Gen 1 mean the same thing, because the creator of the standard, for unknown reasons, decided to rename the old interface.
We don’t know yet another case similar to that of Xiaomi, but according to HDMI LA, there may be more to come.
HDMI 2.0 vs. HDMI 2.1
HDMI 2.0 uses TMDS encryption, which means a data transfer rate of up to 14.4 Gbps. HDMI 2.1 deploys more efficient FRL encoding, while increasing throughput to 48 Gbps. Uncompressed video at 3840 x 2160 pixels with 8-bit color depth and 60 frames per second swallows 11.94 Gbit/s every second. So HDMI 2.0 is enough for that while retaining audio, metadata and some overhead.
But the new PlayStation 5 and Xbox Series X game consoles already feature 4K resolution with 10-bit color and 120 frames per second. The image component swallows only 29.86 Gbit/s. Twice as much as HDMI 2.0. In addition, the original binary version does not even support HDR, and support for static metadata was only offered through the newer HDMI 2.0a (HDR10) and 2.0b (HLG) variants. Dynamic HDR formats like HDR10+ and Dolby Vision already require HDMI 2.1, which is also important for playing movies, not just games.
New features in HDMI 2.1 also include Variable Frame Rate VRR (also known as FreeSync), AALM for automatic post-processing effects that increase input lag (a key for gaming), and DSC compression, which allows HDMI 2.1 to be used for higher resolutions and frame rates.
When buying, you will have to follow not only the HDMI 2.1 designation, but also detailed specifications, since the logo does not guarantee higher throughput or support for VRR, AALM and DSC.
With HDMI 2.1, it was really fun before this “relationship”, and also in terms of console gaming. For example, LG introduced its CX series OLED TVs, which had an HDMI 2.1 transfer rate of only 40 Gbps. Xbox Series X has the same limitations.
Sony produces only 32Gbit/s on PS5, so that’s not enough to get 4K, 120fps, 10bit color with HDR and the image has to be resampled to YCrCb 4:2:2, so it looks ugly (especially when rendering text) . Unlike Microsoft, Sony has not yet studied the console to work with a variable frame rate, so games risk image tearing.
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