Flickering on a mate object

[marchermitte]

Hello
I'm trying to render a quick animation, so settings are pretty low. I'm using Direct Lighting with an HDRI background image only to light the scene. There is a mud river object and a terrain used as a mate object, as the river needs to be comped over a real footage later.
I'm noticing big "light" stains flickering on my mate object (which is invisible but leaves some traces in the alpha, such a shadows) Mate object is using a diffuse material.
I was using adaptive sampling, should It be disabled for animation? Coherent ratio is at zero.

Thank you

[juanjgon]

The problem can be related to using a low number of samples, the adaptive sampling, or perhaps even the epsilon parameter in the kernel if the scene is too big. Can you please try to adjust this parameter to check if it helps?

Thanks,
-Juanjo

[Mastoy]

Have you activated static noise ?

[marchermitte]

Sorrty for not answering earlier, this job gets me working all nights for a week now.
Yes, I (always) activated static noise. I think This was mainly due to the adaptive sampling. I'm wondering if It's wise to use upsampling for an animation? Trying to cut rendering time here, quality is not a main concern but flicker free and noise is, I lowered pretty much everything (specular, diffuse and refraction depth) and I'm using direct lighting, occlusion mode. Still, 3 minutes per frame is too much for the time I have left.. I'm surprised as I've got 2 GTX 1080 ti.

[promity]

what is the time difference between diffuse and AO GI? In my current project (a factory interior with a lot of animated equipment) in diffuse mode, my two 2070s give about 1 m 40 s, and in AO mode - about 30-40 seconds. So the difference is enough.