CRF vs ABR

[meadrocks]

I do movie backups only, hevc, aac, 1080 to mkv file. I set Encoder to Highest (very slow), I have a very fast cpu. What is the difference between CRF & ABR, and which will give the highest video quality? I know for 264 encodes you've recommended 23 as a good CRF. Is 23 also a good setting for HEVC?

Thanks.

[sneaker_ger]

CRF is recommended over single pass ABR for both x264 and x265. Is 23 good enough? That's subjective. Only you can decide. Most users seem to use 20 or 18 from what I can see. But those aren't absolute measures of quality anyways. crf 23 using x264 will look different from crf 23 using x265. And crf 23 using x264 preset veryslow will look different from crf 23 using x264 preset superfast (or more generally: many settings have influence on the output quality).

I suggest you do a few tests (e.g. 16, 18, 20, 21.5, 23, 25) and see for yourself.

[meadrocks]

From http://slhck.info/video/2017/03/01/rate-control.html

"CRF ranges from 0 to 51 (like the QP). 23 is a good default for x264, and 28 is the default for x265. 18 (or 24 for x265) should be visually transparent; anything lower will probably just waste file size."

[mparade]

From http://slhck.info/video/2017/03/01/rate-control.html

"CRF ranges from 0 to 51 (like the QP). 23 is a good default for x264, and 28 is the default for x265. 18 (or 24 for x265) should be visually transparent; anything lower will probably just waste file size."

I am currently testing x265 at CRF=24 with main10 profile...it seems one can start to forget using x264 for archiving purposes at least...:eek:

[jdobbs]

I find that 23 is typically sufficient for HD output -- but I usually use 20 or so for SD. I can't give a good reason why -- but I've come to that conclusion based on experience.