Drovp plugin for upscaling images and videos with Real-ESRGAN or waifu2x (nihui/waifu2x-ncnn-vulkan) neural networks.
Why both? I personally find ESRGAN to be better for art, and waifu2x for photos.
NOTE: If you're getting GPU related or any errors at all, try setting the GPU ID option to -1, which switches waifu2x into a slower, but more reliable CPU mode.
NOTE 2: Upscaling videos takes considerable amount of time and space, since all frames have to be extracted into lossless png files, upscaled one by one, and only then re-encoded into a new video (details in #1).