From what I have observed, it appears that VEAI does look at 20-30 frames prior, but future frames don’t have any impact.
What has led me to this conclusion is that I have been letting VEAI export the frames as .png and then closely comparing the results with different settings. I began to notice though that what I was seeing when exporting individual frames for comparison was not actually the same as what I would get if I looked at the same frame as part of a longer export with many frames either side.
So I did some brief testing and noticed that if I export 30 frames prior to the frame I’m interested in, I get the same result as if I exported the full video. But if I only export 20 frames prior, I get a different result. And reducing that number of prior frames results in yet different results each time. The differences are quite minor, but they are there. Sometimes they can be quite noticeable too, so it’s something to bear in mind if you are really trying to fine tune your parameters.
I also tried seeing what happened if I exported 30 frames either side vs just 30 frames prior, and there was no difference, which leads me to the conclusion that later frames have no impact, only those before.
This was with Proteus Fine Tune V3 upscaling from 1080p to 4K. I haven’t tested with any other models.