I asked about flickering several years ago in this forum, and learned a good bit about it and GI cache files, etc. at the time. Nevertheless, I've still somehow end up with flickering whenever I have a lot of plants or trees in the animation, even though I do use a GI cache file (and have it blend up to 20 files!) Sometimes it's not so bad, but in one old set of frames (that I'd like to use now) it bugs me enough to ask about it again.
In this case, it's about a 10 second scene which takes a long time to render even on my decent PC. As a workaround, because the camera stops panning at one point, I render only as much animation as I need to reach the point where the camera movement stops. At that point the background becomes effectively static, which would let me take the last frame and use it as a still shot for the background since nothing will change after that. However, because there's flickering in the animation of the plants...when the camera stops turning and it goes to the still shot background, the sudden stop of the flickering is noticeable. It might not be unusable since attention should be on other things in the scene....but if the flickering wasn't happening it would be seamless. So, while I go back to trying to resolve this...
I'm curious if anyone knows of a plugin for Premiere Pro or (AE), or Davinci Resolve, that is able to smooth out this kind of flickering? There are plugins that will fix flickering from lights and timelapse sequences, but I don't know if those would handle this kind of jittery flickering. Any suggestions, I'll be glad to try them and report back.
I got the below data from Oshyan. Might help you...
"GI Cache blending. It's useful for reducing flicker in GI/lighting in animations.
If your scene is appropriate for a slow down you could use Twixtor from RE:Vision.
The flicker is still there but more you slow it down it is more and more less apparent.
I was curious and slowed down a file with the Twixtor demo.
Then i speed it up to normal . There is less flicker but not much difference.
And that is because mostly of the resampling then the twixtor effect probably.
You could add a little more motion blur to the beginning to make lessen the flicker.
But i think you have tried those kind of things already.
If the scene is suitable for that kind of change you could add the twixtor (or similar effect) with keyframing.
Use zero slowdown(use original speed) near the end and at the end 100% or 99% kinda high slowdown to make the transition less abrupt for example.
It depends on your scene so can't say much.
Arguably this belongs more in "Open Discussion", if you're asking exclusively for *non-TG* methods of reducing noise (i.e. in post).
That being said, I would guess you are dealing with noise due to antialiasing (or lack thereof), and so GI caching won't help. This can be a tough thing to handle if render times are a consideration (and of course they usually are). One thing I would note is that often times if you have very high detail (e.g. lots of branches, high resolution textures, etc.) vegetation models and are seeing them entirely or mostly in the distance, then it makes things a lot harder for the renderer to antialias properly. In these cases it can be beneficial to actually use a lower detail model (at the very least, lower detail/resolution textures, especially opacity) not so much to save render time but to make it easier to antialias the detail in the scene. I'm not sure if that makes sense, but trust me, it helps. ;)
But it sounds like you don't want to have to re-render, right? In that case I would imagine only some motion blur, or another frame blending method of some kind would help. Although noise reduction could also potentially work, especially if it's temporal.
If you're using Adobe After Effects, my first thought with a noisy video would be to use the Apply Remove Grain. If the grain is too much and you end up with blurry video, I'd due a high pass type sharpen overlay for you video.
https://www.youtube.com/watch?v=VxWpxUx1_t0 This video was done with alpha footage of Battlefield 4, done by a cam at a convention, it required mass post work, but came out "decent", and I was just starting to learn After Effects. Pretty sure original video was 480p