correcting images with heavy moiré / aliasing

I am in charge of converting some videos for projection on a big screen during a musical (target = full HD)
I have received some videos, obviously made by someone who doesn't have a clue on the technical side of things, and these UHD MP4 clips contain material that has been composited from different sources (HD or lower Youtube backgrounds, UHD smartphone camera, etc.) and the UHD format is grossly overkill for the actual quality of the content. So be it. But the most obvious artefact is very strong moiré on fabric patterns, clothes of the main character in the clip, resulting from an unmanaged succession of resizing/downscaling/upscaling etc. (probably with free editing tools).
Question, is there a way (a combination of filters in Resolve Studio 18 ?) to somehow soften the moiré where it hurts the most ? I have to scale down the resolution anyway from UHD to FHD, but that alone will not fix the problem. Is targeted softening the only tool ?
Thanks for sharing ideas.

Ben, here’s one way to deal with the moire on fabrics. You will need DVR Studio for the Deflicker effect. You will also want to do this at the beginning of your node tree.

1. Add a first node (before any color manipulation nodes). Mask and track the fabrics that have the moire on your shot. You might have to track manually if there’s substantial movement but that should be easily done in Resolve.

2. Add another (2nd) node and use the blur tool to so lightly soften the patterns, but not too much to lose the patterns. Alternatively it may be that you are better off to use the sharpen control and very slightly to unsharpened the pattern instead of a blurring effect.

3. Add a 3rd node, use the deflicker effect to reduce the flickering on the moire. You’ll have to play with the different flicker settings although one that I have success with is setting it to Floro-lighting since many moire or aliasing is kinda like a fluorescent light flickers. This effect is only available on the Studio version.

Good luck to you! BTW, you should have posted this under the DaVinci category. It’s where you can get more ideas on the topic as opposed to in the “Off-Topic” category.

Thanks for the suggestion, I will give it a try.
I posted here b/c I thought this question was too generic and could perhaps be solved by other tools than Resolve ...

When I had to tackle moiré issues in some clips for a presentation, I found that using a subtle Gaussian blur on the problem areas really helped smooth things out. I also played around with the color correction tools, adjusting the saturation and hue in those spots, which made a noticeable difference. Masking can be super useful too if you want to be more precise about where you're applying the effects.