HDMI 2.1a standard upgrade: Source-Based Tone Mapping for PC gamers

The HDMI Licensing Administrator has confirmed that a new version of HDMI 2.1 is coming -- HDMI 2.1a -- and with it, will enhance and optimize the HDR experience through Source-Based Tone Mapping (SBTM).

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This new technology requires source and target devices to both be supported in the new standard (as in, the console/PC and the TV/monitor) but the HDMI LA expects that there will be a slew of SBTM firmware updates throughout 2022. SBTM will be a boon for PC users and gamers, especially for those working with multi-window systems.

The source of the image (the GPU for example) has control of the tone mapping, as HDMI 2.1a-enabled devices will let users have separate windows with SDR or HDR optimized content... at the same time. HDR technologies like HDR10, HLG, etc will remain -- HDMI 2.1a isn't adding anything there -- instead, it improves the HDR experience across the board.

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HDMI.org said: "Source-Based Tone Mapping (SBTM) is a new HDR feature that allows a portion of the HDR mapping to be performed by the Source device instead of the Display device. SBTM is especially useful in cases where HDR and SDR video or graphics are combined together into a single picture, such as picture-in-picture or a program guide with an integrated video window. SBTM also enables PCs and gaming devices to automatically produce an optimized HDR signal in order to maximize the utilization of the display's HDR capabilities without manual user configuration of the Source device".