I’ve stumbled upon an Oculus article about ASW2 yesterday, sometimes coincidences are amazing!
To keep it short: ASW2 is using NVidia Optical Flow SDK. This might be the case for SteamVR Motion Smoothing as well because I remember it used to be available for NVidia hardware only when first introduced (or was it WMR instead? I’m not sure)
An Introduction to the NVIDIA Optical Flow SDK | NVIDIA Technical Blog
ASW and Passthrough+ with NVIDIA Optical Flow
NVIDIA announced their optical flow SDK earlier this year, while it operates as a replacement to the previous motion estimation-only mode of the NVENC video encoder. Available on Turing hardware, NVIDIA optical flow quadruples the macroblock resolution, increases motion vector resolution, enables following objects through intensity changes, and emphasizes plausible optical flow over compression ratios. The result is half the average end point error than traditional video encoding motion vectors. The qualitative results are equally impressive. With ASW, near-field objects track more reliably. Swinging flashlights hallucinate motion much less frequently and the increased precision means movement is tracked more accurately to individual particles and objects.