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When using media players such as the Apple TV 4K, many users notice a brief blackout of the picture when starting a movie or series. This is caused by the TV changing its refresh rate after matching the frame rate to the content being played. The solution is HDMI 2.1 QMS, Quick Media Switching, which allows switching between different refresh rates without a momentary loss of picture.
What is HDMI 2.1 QMS and how does this technology work?
Quick Media Switching, or QMS, is an optional feature of the HDMI 2.1a standard that eliminates the brief black screen that appears when the frame rate changes. This happens, for example, when a player automatically matches the display's refresh rate to the content. Movies are most often shown at 24 frames per second, while TV broadcasts may use 25, 30, 50 or 60 frames. The TV then has to change its refresh rate, which causes a short blackout. QMS uses a mechanism known from VRR, but it's a separate feature designed specifically for video playback rather than gaming. Thanks to Video Timing Extended Metadata, the source device notifies the TV of an upcoming change before it happens. That lets the refresh rate switch almost instantly and without the annoying black screen. The feature works with any HDMI cable and doesn't require buying special cables. However, to use it both the TV and the player must support QMS.
Which devices and TVs support HDMI 2.1 QMS?
The first player to offer HDMI QMS support was the Apple TV 4K from 2022. The feature makes most sense in devices that offer automatic frame-rate matching to the source material. On the TV side, LG was the first to announce support, and the technology later began appearing in models from other manufacturers. Currently the list of compatible devices is made up mainly of LG, Samsung and TCL TVs from model years 2023 to 2026. Supported models include, among others, the LG C3, C4, C5 and C6 series, LG G3, G4, G5 and G6, Samsung S90C, S90D, S90F and S90H, Samsung S95C, S95D, S95F and S95H, and numerous TCL models from the C, QM and X series. In the past Sony said it did not plan to implement QMS, while Philips said it would consider adding the feature in the future. It’s worth remembering that simply having HDMI 2.1 or VRR support does not automatically mean QMS compatibility. It’s a separate feature and its implementation is up to the TV manufacturer.
HDMI 2.1 QMS eliminates the momentary black screen that can occur when the refresh rate changes during playback of movies and TV series. To use it, both the TV and the playback device must support it, and the number of compatible models is steadily growing.
source: flatpanelshd
