X265 slow preset further adjustments modifications?

[YaBoyShredderson]

In trying to encode 4k hdr blurays in staxrip, with transparency as the goal. I use the slow preset and crf 20 ssim tune (using this for testing, will get rid of once ive settled on the settings).

Is there any further adjustments i can make in staxrip to improve things a little bit further without going to far into the diminishing returns territory? And without slowing things down to a crawl (more of a crawl than it already is).

Another question, im trying to retain hdr, and ive selected the hdr injest option, thinking i need this to do it, but its producing 2 files at the end with slightly different mediainfo information. "Name"_new.mkv looks normal in media info. But the second file "name_new.mkv_hdr10.mkv has different mastering display luminance, max cll, and max fall, with an aditional line under each, saying the original information. Which on of these is correct?

[microchip8]

you can increase psy-rd and psy-rdoq and with hme=umh,umh,star you can shave off between 100 and 200 MB but it'll slow down the encoding a bit

personally i use a psy-rd of 3.3 and psy-rdoq of 16. It really helps in dark scenes. qcomp of 0.7 is also worth a try

[RanmaCanada]

You could bring the CRF down to 18? From going through the forums here, it appears that most people do their 4k encodes at 16. HDR compresses really well, if it's a true 4k movie without a lot of grain.

[YaBoyShredderson]

Originally Posted by RanmaCanada

You could bring the CRF down to 18? From going through the forums here, it appears that most people do their 4k encodes at 16. HDR compresses really well, if it's a true 4k movie without a lot of grain.

Yes i have noticed very low bitrates at crf 20 across the different tests, the average is around 10, im in the middle of the crf18 tests and its coming out around about 15 (though not all of the movies have been done yet so it could change)

I use 18 for 1080p blurays and that has been fine. I thought with higher resolutions, you can use higher crfs, so thats why i started with 20.

[Boulder]

The thing with HDR stuff requiring a lower CRF for the same quality level is that the image is very flat so the encoder will give it much less bits compared to SDR at the same CRF. I use settings close to --preset slower and CRF 15 + qcomp 0.7 for 1440p and CRF 16 + qcomp 0.7 for 1080p encodes with HDR.