This paper is quite old and has known problems with setting a constant quantizer for VP9. The results do not match my own findings comparing libvpx and x265 at all [1]. libvpx VP9 is still worse than x265, but the difference is quite small.<p>[1] <a href="https:&#x2F;&#x2F;arewecompressedyet.com&#x2F;" rel="nofollow">https:&#x2F;&#x2F;arewecompressedyet.com&#x2F;</a>