ACES IDT for iPhone 13 HDR Rec.2100 HLG Dolby Vision

Hello, I am new to this forum, as well as new to ACES, I have been reading many articles and a lot of information on the subject, seeing how ACES works and its different applications and ways of working, currently I have a question, I am working with material recorded by an iPhone 13, they are HDR Dolby Vision videos, apparently the characteristics of the material are:

-Codec/Format: HEVCMain10 video in AppleQuicktime container (.mov)

-HDR Format: Dolby Vision with HLG base layer (Profile 8.4)

-Transfer characteristic: HLG(ITU-R BT.2100-1)

-Color primaries: BT.2020

-Chrome Sampling: 4:2:0

-Bit depth: 10 bits

When trying to work with ACES in Davinci Resolve, I have realized that there is no IDT with these characteristics, the only thing that exists is a: Rec.2100 HLG (1000 NIT), which I have read right here in the forum that being It would be a waste of an ODT to implement it as an input, so my question is how can I replace or find a suitable IDT for my videos, or how can I make an input LUT or DCTL that works as an IDT, or just how can I solve this problem?

It is worth mentioning that I am shooting in HDR to capture more dynamic range in my shots but the delivery would be in Rec.709 or sRGB, but I want to have a backup of the material in HDR in case I have to deliver in HDR.

I am currently using Davinci Resolve 17.4.6 and ACES 1.3

I hope someone has already dealt with this before and can help me, thank you very much for reading.

Cheers!

1 Like

Hi Esteban,

Dehancer already provides an IDT for iPhone Rec.2100 HLG.
(I’m not associated with the Dehancer developer. I’m just a user of their product).

If purchasing Dehancer is not desirable, I will write here a way to create an ACES to ACEScct using CST - LMT - CST sandwich in a Resolve node tree. But I’m not in front of Resolve at the moment, and these days I’m a little busy at the studio.
I would try Dehancer’s free demo first.

1 Like

Cool! thanks for the tip, what would be the correct way to create this transformation using the node tree?

Not sure about the Dolby Vision part of iPhone material and how to leverage that data, but for the encoding itself you could try a CST to convert from Rec.2020/HLG to ACEScct and see if that is accurate. I think inverse OOTF should be enabled for that too.

1 Like

Thank you very much for the tip, I’ll try

Hi Estaban. The wrinkle with using those iPhone files as is in Resolve is that the iPhone capture is tuned to account for the Dolby Vision metadata, but at the moment, the only apps that read that metadata are Compressor and FCP (and possibly Motion, but I haven’t tested it in Motion). So if you want to use the DV metadata before your IDT the work around is to first put the files through Compressor (which will read the Dolby metadata) and transcode with a transform to a suitably wide space, like PQ REC2100, and then from there you can use the CST in Resolve to move the files to your preferred working color space.

2 Likes

Excellent data and thank you very much for the tip, I will try to do the transcoding and I will share the result

do you mind elaborating? How would any metadata change the conversion from HLG to PQ The DoVi Metadata afaik is to convert from HLG to SDR, or to less capable displays, the HLG to PQ conversion was written in some EBU tech paper afaik but it was mainly the other way around where the programm peak luminance of the PQ signal was mapped to 100% HLG as HLG is relative.

Maybe I am missing something with the iphone DoVi profile? I find this interesting as I kind of assumed iPhone was shooting scene reffered HLG… ( just that the default exposure was like 2+ stops over…) I am also not sure what the DoVi metadata would even do, it all sounds like HDR10+ where it just analyses the content once and then tries to create metadata based on scene detection etc.