Problems with LUT being read in Resolve to Avid Workflow

[Scott Clements]

Hi, Glenn.

I understand.

My Avid project is not BGB, but YCbBr 709.

Here are more experiments I did that I posted in the Avid forums:

If I remove the “Levels scaling (video levels to full range)” color transformation from the AMA-linked ProRes 4444 clip and still keep the rec 709 Lut applied….

And then render out a flat transcode from Resolve, with no LUT applied and bring it into Avid…

I can only get the flat transcode to match the AMA clip, if I change it’s source settings to add the rec 709 Lut and then the “Levels scaling (full range to video levels)”

But, if I just bring in the AMA and the flat resolve transcode and then just apply the rec 709 LUT, they look different

And this is the kicker….I can get the flat resolve transcode to match the AMA-linked defaults (of video to full, followed by rec 709) if I change its source settings to this: Levels scaling (video levels to full range), then I add the rec 709 LUT, then I add Levels scaling (full range to video levels). That’s 3 separate transformations.

Weird. I don’t really know what all this means. I am thinking of rendering out flat Resolve Transcodes as an emergency backup.

Film Editor, London UK
http://www.scottclementseditor.com

[Glenn Sakatch]

What are you transcoding these to in Resolve? You said the originals were prores444s, but I don’t think you said what you were transcoding them to to bring back into Avid.

Glenn

[Scott Clements]

I am transcoding from ProRes 4444 to DNxHD 115 mxfs. I then put the mxfs in a numbered avid folder, rescan and put the database file in an Avid bin.

Film Editor, London UK
http://www.scottclementseditor.com

[Glenn Sakatch]

It gets very confusing with all the transformations you are going through to totally follow along.

So you are taking a file that probably should be tagged as full levels into resolve, and you are outputting it as mxf as auto, which is typically going to get tagged as video, and it appears as though it is. You tried turning off auto, and video looked the same.

You might want to check in Resolve the clip attributes, and see how resolve is viewing the clip. Switch it from auto to video or full and which one changes the image. Perhaps Resolve is interpreting it as video instead of Full.

“I can only get the flat transcode to match the AMA clip, if I change it’s source settings to add the rec 709 Lut and then the “Levels scaling (full range to video levels)”

I’m not sure how a flat transcode out of resolve would need a 709 lut added in Avid. Flat usually means it still looks …flat.
Are you saying when you bring your flat transcode into Avid it already has a 709 look to it?

What are your camera raw settings set to in Resolve? Sounds like you have some metadata being added somewhere along the way that might be leading to the issue. Do you have a view lut or anything like that going on in the resolve color management?

Glenn

[Scott Clements]

Sorry for the delay in responding. The project is now over and everything turned out fine.

“Are you saying when you bring your flat transcode into Avid it already has a 709 look to it?”

No, it’s flat, but at least I can start at the same place as the AMA stripped of it’s colour transformations to see what’s going on.

“What are your camera raw settings set to in Resolve? Sounds like you have some metadata being added somewhere along the way that might be leading to the issue. Do you have a view lut or anything like that going on in the resolve color management?”

Sorry, I don’t know Resolve inside out – not familiar with ‘camera raw settings’ – can’t check now, as I no longer have the rushes. The ProRes files had an embedded LUT, but Resolve didn’t see it. I could see it in the Arri Color tool, and Arri’s Avid AMA plugin used it.

I feel very confident Arri’s Avid AMA plugin is wrong. I looked at it on some shots where it was crushing the blacks way too much and I knew it was way off.

Anyways, the project is over, so the heat is off. I’ll contact Arri about this and see if they know what’s going on. Thanks for the help!

Film Editor, London UK
http://www.scottclementseditor.com