UHD BD to BD?

[zoidberg]

Cool. A well done SDR conversion of Die Hard, regraded to the Netflix colours is the way to go I think. I've been doing tests and I'm able to regrade the original blu ray but the UHD would be a much better source due to the blu ray's blown highlights.

You guys are blazing the trail! I tip my hat to you.

[X5gb]

Zoidberg, maybe its better if you want to regrade it to netflix that it is done by someone who can do the conversion from hdr to sdr and the colour match at the same time rather than work on one that has been already converted to 1080p sdr as that means two lots of conversion and a further loss of quality. I believe TomArrow did that to the The Mummy 1999 uhd by using the bluray colours.

[zoidberg]

But using a script like Chew's or a variation thereof you can obtain a lossless intermediate file at 1080p or 2160p which would be the basis for a regrade before downconverting to 4:2:0 YV12. Any losses should be minimal.

[X5gb]

Afraid all that scripting stuff is a little over my head, I'll stick with ripbot for know, took me long enough to get around all the Premiere editing and tweaks like expanding frame and grain plates etc. But if ripbot keeps on messing up and freezing for me I may ask Chew for help with a script to do it in Virtualdub. I'm sure someone else will be able to deal with Die Hard and colour grading it anyway.

[X5gb]

Another software I've just found out can do this is CloneBd. From what I've read it can make use of Nvidia acceleration for conversion (gtx 10xx recommended) to considerably speed this process up but you need the full UHD bdmv folder structure, can't work with mkv. Marban on BS forum just did a 30mbps sdr conversion of Die Hard using it. Anyone tried it and compared conversion to ripbot.

[Beber]

Here's a RipBot264 hue test on Men in Black II to see where it goes colorwise whether you go positive or negative:

Actual Blu-ray:


UHD MadVR:


UHD -> RipBot264 (hue 0, sat 1, bright -2, cont 0.9)


UHD -> RipBot264 (hue 5, sat 1, bright -2, cont 0.9)


UHD -> RipBot264 (hue -10, sat 1, bright -2, cont 0.9)


UHD -> RipBot264 (hue -5, sat 1, bright -2, cont 0.9)


My preference would be this last one, with a -5 hue.

[deleted user]

But using a script like Chew's or a variation thereof you can obtain a lossless intermediate file at 1080p or 2160p which would be the basis for a regrade before downconverting to 4:2:0 YV12. Any losses should be minimal.

Question is, why even go down to 4:2:0?

You have the higher chroma resolution of the UHD, so at 1080p, which is exactly 50%, you have a valid 4:4:4 image, so you can encode it that way!

[deleted user]

Zoidberg, maybe its better if you want to regrade it to netflix that it is done by someone who can do the conversion from hdr to sdr and the colour match at the same time rather than work on one that has been already converted to 1080p sdr as that means two lots of conversion and a further loss of quality. I believe TomArrow did that to the The Mummy 1999 uhd by using the bluray colours.

Yep, though admittedly I did not manage highlights in that version. For some reason I did not think of doing that. It still looks largely ok tho. My main goal was getting the significantly sharper image of the UHD while keeping it in the look of the BD (which also has blown highlights). It's not a 100% match either, more like a somewhat close approximation, as the UHD has more dynamics between scenes in terms of brightness.

[zoidberg]

You're of course right Tom, you would essentially have DCP quality (depending on the compression quality).

But the thread is about UHD BD to BD so that means 4:2:0 chroma.

[Beber]

Latest tests for Die Hard, trying to approximate the Netflix look:

Netflix / RipBot264 (hue -4, sat 1.4, bright 2, contr 1.2) / RipBot264 (hue -4, sat 1.4, bright 2, contr 1.1)