V-Ray Sky animation ugly gradiant flicker

[dimension3plus]

Hey guys,
Maybe you have an idea to solving the following problem:
In a scene I have an animated VRay Sun + vray sky in the background. When rendering I don't get a clean gradient, there are some minor stripes/blocks visible. After putting it in After Effects and exporting it with h.264/h.265 I got a really ugly gradiant flickering, even with high setting like 50mbps.
I tried to save pngs with 8bit and also .exr with 16 bit float but I'm still disappointed with the result.
Any ideas how to render a smooth gradient in the first place?

Best,
Olaf

[kosso_olli]

I just tested it, you will get a clean and smooth gradient in 32bit. I suspect this is an issue of postproduction and color grading, maybe even a codec issue.

[dimension3plus]

Thanks, I'll double check it with 32bit. Could you produce a flicker free (color bending free) MP4? How is your workflow after the rendering? AFX? Codec?

[dimension3plus]

No success. You can check it out here:
https://documentcloud.adobe.com/link...b-8529e0986d62

Remdered EXR file sequence 32 bit float. Compressed with adobe media encoder h.264 50mbps (highest) CBR.

[kosso_olli]

Well, as I said this looks like some form of compression/artifact issue from post production. Here is a screengrab straight out of the framebuffer, 8bit actually. Looks flawless.
I have no experiece in encoding mp4 files, sorry.
Anyway, V-Ray is not at fault here.

[squintnic]

add some noise / grain to it before export

[joconnell]

You're screwed with 8 bit, it doesn't have enough levels of colour (only 256 shades of each of red / green / blue) for things like very gradual skies - it's the same issue when filming on dslrs. Some of the fancier video oriented cameras have a 10-bit codec so you go up to 1024 options per channel and it gets around this problem. As someone mentioned, grain can help to break up the horizontal bands but your h264 compression might freak out with that too and give you something that looks like blotches / quilting instead of stripes :/

[dimension3plus]

Thanks guys, the hint with the grain has mostly solved my problem!