stable-diffusion-webui-vid2vid VS multidiffusion-upscaler-for-automatic1111

You could use Stable Diffusion. If you use A1111 webui there are extensions for transforming video. If wanted to only transform the faces you could use ADetailer to automatically detect them in the video and inpaint them.

You could try Stable Diffusion. If you use A1111 webui you can use the stable-diffusion-webui-vid2vid extension to convert each frame with models and prompts of your choice. If think that if you could render depth or normal maps you could also use these as hints to ControlNets which would improve your results. The problem with converting video like this is always consistency. The individual frames may look great but there are often noticeable variations in details between them. You could search r/StableDiffusion for vid2vid to see examples of what people actually achieve.

Use tiled VAE, it will save VRAM: pkuliyi2015/multidiffusion-upscaler-for-automatic1111: Tiled Diffusion and VAE optimize, licensed under CC BY-NC-SA 4.0 (github.com)

My favorite solution is to not use ultimate Sd upscale and instead use multidiffusion-upscaler.

sure, i personally use 'tiled diffusion' https://github.com/pkuliyi2015/multidiffusion-upscaler-for-automatic1111, works like charm also use adetailer for faces if its needed.

What worked for my 1080 was using TiledVAE and turning down the quality of my previews - I don't pay much attention to it/s but it's definitely faster than using --medvram, and now I can handle batches and large resolutions without things exploding on me.

I would highly recommend adding https://github.com/pkuliyi2015/multidiffusion-upscaler-for-automatic1111 to your A1111 installation, TiledVAE is enabled automatically under the hood in A8R8; this will allow you to get even larger generations before getting an out of memory error. You'll get a Tiled Diffusion checkbox with some reasonable hardcoded defaults as well.

Use Tiled VAE https://github.com/pkuliyi2015/multidiffusion-upscaler-for-automatic1111

That's weird. 10GB should allow you to hires to 2048x2048 at least. Use Tiled VAE extension https://github.com/pkuliyi2015/multidiffusion-upscaler-for-automatic1111 that will allow you to go even beyond that.