What resize method to use in x264 cli ?

As with avisynth, as long as you don't use point or bilinear, the rest are fine.

Btw, i see you can specify the input resolution by : --input-res Is there useful sometime ?

That's for feeding x264 raw uncompressed video data.

lanczos in libswscale with default number of taps (3) sometimes produces artifacts. You may reduce taps to 2.

My bad. Currently you cannot set parameters for resizers. So submit a feature request to x264 developers.

libswscale now is a part of ffmpeg Hope someone to feedback it to ffmpeg developers... (as my very poor English and I don't know how to feedback...)

I'd certainly say that it's safe to assume that for 99% of users, x264 cli's resizers are certainly good enough. In fact, plain bicubic is good enough for most purposes ;) I rarely (if ever) bother with anything more exotic these days. Derek

I almost exclusively use spline in both Avisynth and x264 CLI, I like the sharpness it gives. Probably ideal for live-action images.

Don't get me wrong, I'm a big fan of spline as well. It's just not a great idea if you care a lot about speed.