Source of x265/CRF

- CRF Guide (Constant Rate Factor in x264 and x265)
--  https://slhck.info/video/2017/02/24/crf-guide.html
- Video Compression Testing: x264 vs x265 CRF in Handbrake 0.10.5
--  http://goughlui.com/2016/08/27/video-compression-testing-x264-vs-x265-crf-in-handbrake-0-10-5/