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odd artifacts in rendered video?

PostPosted: Thu Mar 11, 2021 12:24 pm
by jamesonguitar
Hi all,

I hope you might be able to help me with the following. I rendered for the first time in resolve 17 yesterday, and this video -
- has some odd artifacts (not sure if that is what I should call them).

If anyone could check out what I mean, the problems occur when I am playing my guitar and move my hand quickly up and down the neck, the whole thing gets distorted visually. eg at time stamp 09:06. If you watch closely there is lots of ghosting throughout.

If you watch the opening 30 seconds of the video, which is a time-lapse type thing, there are lots of odd moments of things moving around that are not intended!

This is edited on a high powered pc with Intel Core i9 9900, 64gb ram, nvidia geforce gfx 2080... so I don't think it is a hardware thing.

It is rendered out to h.264 mp4 file in 4k with rate control vbr high quality.

Any help will be much appreciated! And if other info will be helpful, please let me know what.

cheers

Re: odd artifacts in rendered video?

PostPosted: Thu Mar 11, 2021 8:04 pm
by Jim Simon
The issue at 9:06 is likely caused by the use of Optical Flow.

But as it's not a slow motion clip, I'm wondering why you're using that?

Re: odd artifacts in rendered video?

PostPosted: Thu Mar 11, 2021 8:13 pm
by wfolta
Your Youtube video is 24 fps. What's the base footage's FPS that you brought in? (To Jim's comment, it could be that you're asking it to use Optical Flow to remap FPS rates.) Also, what kind of compression are you using for your output?

Re: odd artifacts in rendered video?

PostPosted: Fri Mar 12, 2021 12:59 am
by jamesonguitar
Hi,

Thank you both for answering this! So, I tend to set my retime processes in the project settings, which i assume only effects clips that then get retimed, which these ones weren’t.

My sony a7s3 records in 23.976 (if i remember that exact number correctly!) and i rendered once to that fps and then once to 24 fps and it happened in both cases.

When you say compression, which setting exactly do you mean?

Thanks again