Render artifacts and pixelation only on export

This happens for a few frames at the edit point, only on this clip, not other edit points from same source clip.

artifacts2.jpg (252.03 KiB) Viewed 5327 times

This happens for a few frames at the edit point, only on this clip, not other edit points from same source clip.

artifacts1.jpg (235.6 KiB) Viewed 5327 times

Hi All,

Any help would be greatly appreciated. I have spent hours now on forums and YouTube and have found what I'd hoped were solutions, but they don't work for me. I have a project, shot on Canon C200 in 4K, 23.98, 8-bit (not the raw). The files have a mild color grade on them. Have done this for years using Premiere and no issues. I have 2 timelines (2 different scripts) - one has rendered totally fine, but the other keeps getting these pixelized artifacts in the same spots. See frame grab. In fact, the color grade was copied across timelines, so they are basically the same level of color. The issue is only about 3-4 frames in duration. It doesn't affect similar clips from same take in the same timeline/

I have: Resolve 17.1 Studio; Mac mini M1 with 16g. RAM

I have tried: Output at ProRes, H.264, H265, change color space, Auto Quality, Restrict to 40-60K, Auto/Full Data Level, replace clip, remove some color grade and others. I have lowered processing speed to 100 / 50 / 25.

As others have said, in the timeline, the playback is fine and there are no issues. Any help or even temperate workarounds for today would help. I have switched from Premiere and Never faced this issue other than once when I had Interlaced media accidentally checked and it happened only on fast action.

As I'm typing this, I had some success lowering the processing speed to "2". But that takes almost 20 minutes to export an 80-second video.

Thank you in advance,
David Johnson - NYC
Canon C200 / Resolve 17 studio (for M1) / Mac mini

Follow-up note. Exporting at "2" Render Speed got rid of it. I'm not sure what happens if I stair step back up. But this sure pops the balloon of excitement I had when this first rendered in about 75 seconds instead of 18 minutes. Again, any ideas would help me improve workflow but I did want to post that after trying all of the other fixes, the super low Render Speed was the only thing that made any effect.

David

Try disabling hw decoding of the source codec (h264 I presume) ?

Smunaut,

Thank you. I will try. Is this the same as unchecking the "Using Hardware Optizmation if available" option? Not sure where I would do this. Yes, in this case it would be the MXF files, which I believe are in H.264 wrapper. Because I'm using the Mac mini M1 (bought as stop-gap to see what else might come out this year before a larger machine), I don't think I have other options. So far, the only fix was to use the 1 or 2 level render and wait the 10 minutes for the 75-second clip.

Thanks,
David

Those look like Optical Flow errors. If so, only thing you can do is not use Optical flow.

They look more like decoding errors to me when h264/h265 (or other interframe codecs) applies the motion vectors to the wrong reference frame.

Hence why I suggested to disable hw decoding off those.

I don't remember where the option is, it's somewhere in the global settings ...