ALLM Auto Low Latency Mode

What ALLM is

Auto Low Latency Mode lets a source device send a signal to the display so it automatically switches into a low-latency picture mode for gaming, then reverts when the source no longer requests it. The feature was introduced as part of the HDMI 2.1 specification, which the HDMI Forum released on November 28, 2017.

Game Mode itself is not new. ALLM's contribution is automation: where Game Mode traditionally had to be turned on and off through the TV's settings menu, ALLM lets the source assert it the moment a game launches and clear it the moment the user returns to streaming, so picture-quality processing isn't left disabled while watching movies. Like every HDMI 2.1 capability, ALLM is optional — a TV or AVR can ship with HDMI 2.1 ports and not implement ALLM, and ALLM can also ride over HDMI 2.0 ports because it is backward-compatible.

How it works

The source signals ALLM to the display by setting an ALLM flag inside the HDMI Forum Vendor Specific InfoFrame (HF-VSIF). The legacy H14b vendor-specific InfoFrame does not carry ALLM — only the newer HF-VSIF defined by the HDMI Forum does, which is why ALLM rides the HDMI 2.1 line of the spec even when the underlying link is HDMI 2.0-class.

When ALLM is engaged the TV switches into its Game preset (or equivalent low-latency mode), which disables the picture-processing stages that add latency: motion smoothing/MEMC, noise reduction, sharpening, and most scaler post-processing. RTINGS' methodology distinguishes "Game Mode" input lag from "non-Game Mode" input lag for exactly this reason — the same panel measures very differently depending on which processing path the frame takes.

ALLM is revoked when the source stops asserting the flag — typically when the user closes the game and returns to a streaming app or the dashboard. The display then returns to whatever picture preset it was using before, restoring full post-processing for movie and TV viewing.

Source and display support

Microsoft's Xbox One X was the first commercial source device to implement ALLM, demonstrated at Computex 2018 — only months after the HDMI 2.1 specification was finalized in November 2017 and before any TVs supporting the full HDMI 2.1 link rate had shipped. Xbox Series X/S inherit ALLM support; the PlayStation 5 added ALLM later via system software update in March 2022.

Most TVs from 2019 onward across LG, Samsung, Sony, TCL, Hisense, and Panasonic implement ALLM, though support is per-model and not guaranteed by HDMI 2.1 branding. Sony markets its implementation as "Auto Genre Picture Mode" rather than "ALLM" on Bravia sets paired with PS5. AVRs from Denon, Marantz, and Sony also pass ALLM through, so the feature still works when the console is connected via a receiver.

ALLM matters for streaming devices because cloud gaming (GeForce NOW, Xbox Cloud Gaming, Luna) and video conferencing apps benefit from the same latency-reducing picture pipeline that local consoles use. NVIDIA's Shield Experience 9.1 update in June 2022 added ALLM signaling so the Shield switches the TV into Game Mode when a game or conferencing app is in the foreground, then reverts on return to streaming.

Relationship to other latency features

ALLM and QFT (Quick Frame Transport) target different segments of the latency chain. ALLM reduces the time the display spends processing each frame after it arrives. QFT reduces the time the frame spends in transit by sending it across the HDMI link at a higher rate than the display refresh rate would require, finishing the transfer earlier in the frame interval.

ALLM and VRR are independent HDMI 2.1 features that operate together without conflict. ALLM controls the display's processing pipeline; VRR controls the refresh-rate timing. A console can assert both, one, or neither, and a display can implement either one without the other. In practice the pair is the standard gaming combo: ALLM gets the panel into Game Mode, VRR keeps refresh tracking the GPU's frame output.

ALLM does not itself reduce latency — it ensures the TV is in its low-latency mode when the source needs it. The reduction comes from Game Mode. RTINGS' input-lag methodology measures the same TV in Game Mode and out of Game Mode and consistently sees the difference run from a few tens of milliseconds up to roughly 100 ms, depending on the panel and which processing features are active. As one concrete example, RTINGS measured an LG B8 OLED at roughly 110 ms outside Game Mode versus 22 ms in Game Mode — about an 88 ms reduction. The HDMI specification defines the signaling, not a maximum-latency requirement, so an ALLM badge does not guarantee any specific input-lag number; implementation quality varies by model.