[TD-Linux]

It's based on --best for VP9 1.4.0 and placebo for x264. Generally improvement tends to be from 30-50%, based on the quality target and content (the lower the bitrate, the greater the improvement). I have objective metrics which test this at http://arewecompressedyet.com/.

If you're more of a visual person, you can take a look at some images here, compressed to 60KB: https://people.xiph.org/~tdaede/pcs2015_vp9_vs_x264/0.25/

Certainly libvpx still has a lot of optimization and tuning work left to do. But there's only so much x264 can do with a 15 year old bitstream format.

[aw3c2]

Those example images are of really low quality video. Usually people who care about image quality do not care about that. Can you show some ~720p 5mb/s x264 versus 3-4mb/s VP9 samples?

[indolering]

Low resolution samples are the norm, I think it's because low resolution makes it so you can see how the compression algorithm works. If you a high resolution comparison, you would need to zoom in to see the difference anyway. There are, of course, compression artifacts that are readily apparent even in high-resolution (chain link fences, transparent wipes, etc) but I suspect that they are in the minority.