Atomos Shogun Flame ProRes422 LOG footage is worse in Premiere than internally recorded LOG

[Swemba]

Trying to diagnose the issue here. Right now I am just not using the Atomos for anything more than a glorified monitor. This was shot on a Sony A7siii in XAVC S S-Log3 internally and recorded via HDMI to the Atomos Shogun Flame with no LUT applied to ProRes422.

I also tested this previously on my FS7 with both HDMI and SDI out and the Atomos footage underperformed the internally recorded XAVC-I. I figured it might just be that camera, but now that is happening with the A7siii i'm starting to think it's my NLE.

The first image is straight S-Log3 from both sources. The second image is with a LUT applied. As you can see the image is dark and there is much less detail in the blacks.

Any ideas?

[R Neil Haugen]

First, I'm wondering about the exposure setup. That line across the bottom ... huh. Underexposed, perhaps?

Next ... I'd rather get a couple of the clips in and test in my setup to better understand what those files are ... like. So if you could say post a dropbox link, might be able to get to them over the next day or so.

Would want if possible internal, and the external. And ... which LUT are you using?

[Swemba]

Neil, I really would appreciate you looking at this! That bottom shot is the most extreme from the film, but was shot at native ISO at 2.8, just couldn't throw much more light on it without it looking "sourcey". It's a good example showing how the blacks are crushed on the ATOMOS LOG though.

I made you a folder with the A7siii footage and correspondaing ATOMOS ProRes422 footage. I also included the LUTs used in this film, but they are probably mostly irrelevant as this issue is with the LOG footage and persists no matter what LUT you use or any at all.

Apologies for the need to sync, couldn't get the ATOMOS trigger to work with the A7siii.

https://www.dropbox.com/scl/fo/tmk9lc58azz3bbn0l1ziq/h?rlkey=uiszsmhugjkoo0kjs94hmpaa7&dl=0

The closest I've found to a solution is on reddit a respondant said that Premiere doesn't show full range for ProRes422 (it shows vidoe range) and I should be using Resolve for color instead lol. That's all I've got to go on.

[R Neil Haugen]

If you have that camera set to full range ... for YUV (technically Y-Cb/Cr) media ... that's an issue right there. That is not correct, doesn't gain any actual visual data, it just records it differently. A marketing ploy.

And you might need to use the Full to Legal Lumetri preset on that clip to make it usable.

ALL YUV media is by standards expected to be "legal" 16-235 ... which is an encoding process. The absolute same data can be encoded either 0-255 or 16-235, and for silly ancient reasons 16-235 is what was specified for YUV media. RGB media is full, and the ONLY stuff that is supposed to be recorded in full.

Premiere simply follows the standard. 

I'll try to get to look at that later today or tomorrow.

[Rag and Bone]

This Atomos note might help.

[Swemba]

Neil I believe you have figured out the issue!
Although I can't find any documentation on changing RGB to YUV (or vice versa) on the A7siii or FS7 cameras. It appears that ProRes422 HQ the Atomos records in is by definition 10-bit 4:2:2 YUV. That's just how it is.

The Full to Legal Range 10-bit Lumetri preset seems to be what we are looking for here.
As far as I can tell there isn't any loss in data once the preset is applied so everything appears to be smooth sailing!

Please let me know if you have any additional information or anything I should keep in mind regarding all of this.
Now heading to Reddit to correct the user that said Premiere can't handle Full Range.

[R Neil Haugen]

There shouldn't be data loss. But it would be better if there's a setting in the camera to switch that back to legal.

[Swemba]

The older ATOMOS recorders like mine unfortunately do not have a legal/full switch. The newer models do however.