Tech company LG’s latest press release about the technical capabilities of their new OLED TVs mentions that the 2023 LG OLED TV models are the first televisions to be certified by the HDMI organization for Quick Media Switching Variable Refresh Rate (QMS-VRR). QMS prevents the TV screen from briefly going black when the player changes the refresh rate. This feature is not new and has been a part of the HDMI specification 2.1 for more than five years. Audio/video receivers with HDMI 2.1 connections that include QMS have been on the market since 2020.
The statement that QMS has been certified by the HDMI organization for the TVs causes confusion as previous announcements usually refer to certification for the entire AV interface, not for individual parts. The reason for this confusion is that QMS was specified twice, once in version 2.1 and then in version 2.1a published at CES 2022. HDMI Licensing’s CTO, Jeff Park, confirmed this duplication and stated that HDMI 2.1a was just a clarification as version 2.1 left too much room for manufacturer interpretations.
However, the correction by 2.1a came late, and some chip manufacturers implemented QMS differently, without VRR as a base. This was a problem as AV receivers with QMS according to HDMI 2.1 were already on sale. Customers who bought these receivers became unintentional beta testers.
The situation now is that devices that strictly adhere to the 2.1a specification have correctly implemented QMS. Therefore, LG’s wording about certification to the recently announced specification is correct. However, there is still a black hole surrounding devices equipped with QMS to specification 2.1, as there has been no official test procedure to reliably determine whether the implementation fits the current specification or not.
The manufacturer Denon supports the unclearly defined QMS in its models specified according to HDMI 2.1 but not for those specified according to HDMI 2.1a. As a result, none of these receivers can use QMS together with the new LG TVs.
This is not only a problem for Denon but also affects receivers from other manufacturers such as Yamaha since Nuvoton chips are in almost all receivers on the market. Customers are settling for misunderstandings between the HDMI consortium and the industry for the second time. However, there is no solution to this problem, and processors with QMS according to HDMI 2.1a will not come from the manufacturer until 2026.
