Have you tried seam carving? There are a couple of plugins for avisynth (both by V.C. Mohan).
Thanks for the tip; I tried it and, despite the fact it does a very good job doing liquid resize, it is suitable just for images, because using video, frames are wildly different between one and the next (and previous), making its result unusable.
I wonder if there is a good inpaint filer that uses the texture synthesis. I would add my thought: probably in ten years the neural net and deep learning computing will do this kind of things perfectly, like video upscale, black and white colorize, inpaint, color matching bewteen two clips… we’ll see!