What would be the cutting edge, open source equivalent for AI upscaling of video?

Not sure about open-source, but a number of friends of mine who work as freelance professional creatives (e.g. ad hoc video advertisements for smaller companies) espouse Topaz Labs’ Video Enhance AI [0] for this sort of work. Anecdotally, seeing the results of their applications of it, it does seem to work astoundingly well— especially for an application that runs fine on hobbyist/enthusiast grade hardware (albeit the render times will likely still be in a multiple of hours for longer videos; personal experience on 3090 / 5950X / 128GB home work machine was roughly 5-8 frames rendered/sec when upscaling 720p footage to 1440p, roughly 12 seconds render time for every second of footage. I imagine the render time would scale with the demands of the selected AI model / output resolution).

I am not aware of any singular FOSS project in creative work that performs similarly to Topaz Labs’ product for all input videos (note to reader: if I am wrong, correct me— I only have second-hand anecdotes to go off of from my friends who work with this kind of work in their careers, and precious little first-hand experience from upscaling old family memories to experiment with the software). As far as I am aware, this is because different upscaling models are trained on, and thus effective / mainly used for a specific type of content. The same upscaling model that was trained on interpolated 480p videos with compression artifacts will not produce the same results as one trained on, say, anime videos/manga, e.g. the models used by Waifu2X [1]. Hence, with Topaz Labs’ application, you select the model that was trained on footage that best matches the footage you wish to upscale.

All that being said, I do know that some (if not all) of the upscaling models Topaz uses are FOSS. Much of their application is just syntactical sugar upon the models it uses, making it easier for non-SWEs to use. I’m not sure whether or not the models that Topaz distributes have any level of training done by them, in house— logically, I would assume as such, otherwise their product wouldn’t be as performant as it is.

[0] https://www.topazlabs.com/video-enhance-ai

[1] https://github.com/nagadomi/waifu2x