@Lentern Hi, check your GPU driver is up to date, & as @Musicvid asked if that is four 4k clips in Picture in Picture view you might be pushing the limits of your pc, recommended is 32GB RAM for 4k (for VP19-20)

You didn't tell us anything about your source or rendered video.

https://www.vegascreativesoftware.info/us/forum/faq-how-to-post-mediainfo-and-vegas-pro-file-properties--104561/

Here's the Vegas media info for one of the files. All four videos are 1080p @ 120fps.
-----------------

General
  Name: .desk Sodium FPS benchmark 24 16.mp4
  Folder: D:\Vegas\Projects\OptiFine VS. Sodium - Minecraft 1.19 Comparison\tests
  Type: AVC
  Size: 610.86 MB (625,523,191 bytes)
  Created: Wednesday, August 17, 2022, 12:27:41
  Modified: Wednesday, August 17, 2022, 12:27:41
  Accessed: Sunday, August 21, 2022, 20:03:00
  Attributes: Archive

Streams
  Video: 00:02:03.500, 119.880 (VFR) fps progressive, 1920x1080x32, AVC
  Audio 1: 00:02:03.455, 48,000 Hz, Stereo, AAC
  Audio 2: 00:02:03.455, 48,000 Hz, Stereo, AAC

Summary
  [TCFM]: 6

ACID information
  ACID chunk: no
  Stretch chunk: no
  Stretch list: no
  Stretch info2: no
  Beat markers: no
  Detected beats: no

Other metadata
  Regions/markers: no
  Command markers: no

Media manager
  Media tags: no

Plug-In
  Name: so4compoundplug.dll
  Folder: C:\Program Files\VEGAS\VEGAS Pro 17.0\FileIO Plug-Ins\so4compoundplug
  Format: AVC
  Version: Version 1.0 (Build 8532)
  Company: MAGIX Computer Products Intl. Co.

Your video is Variable Frame Rate, with which Vegas Pro 17 is not fully compatible. If you want to edit it in Vegas, convert to CFR first in Handbrake.

Your video is Variable Frame Rate, with which Vegas Pro 17 is not fully compatible. If you want to edit it in Vegas, convert to CFR first in Handbrake.

I have Vegas 365 so does Vegas 20 support this? And if so, could that fix the artifacting? I also have Vegas 18 installed already.

Maybe. Best thing is not to capture VFR.

We use OBS capture a lot here.

I used HandBrake to re-encode the videos at a constant frame rate but I'm going to wait until tomorrow to do the render. I'll report back with the results. I'll try Vegas 17 and 20.

why do you capture with 120fps anyway? as far as i know no streaming service like twitch or youtube support 120fps. for slowmotions?

maybe a rewrap would already solve some problems? like from mp4 to mov or from mov to mp4. but again, if you would need to reencode it anyway to cfr why not capture it that way in the first place? or is this just a one time project and you have only this material to work with?

maybe a rewrap would already solve some problems? like from mp4 to mov or from mov to mp4. but again, if you would need to reencode it anyway to cfr why not capture it that way in the first place?

@eikira rewrapping causes variable frame rate, so it may already be rewrapped, while his original capture in MKV format was a constant frame rate. He hasn't provided much info to know

I rendered the video again with the constant frame rate videos but experienced the same artifacting, even after using Vegas 20. I'm not sure what else could be the problem.t capture it that way in the first place?

while his original capture in MKV format was a constant frame rate

The original video from OBS was 119.88p constant. It was recorded to MKV and remuxed within OBS to be an MP4 file. Would there be another built-in rendering codec I could use to possibly fix this?

Could you share a screenshot of the exact settings you used in OBS? It might give a hint.

Could you share a screenshot of the exact settings you used in OBS? It might give a hint.

Here you are.

i still dont see the need to capture in those high frame rates... (beside it says in OBS variable and not constant). why not just record in 60fps constant?
and since you just dont give us real information about your system, the vegas settings and what render profiles you are using, we can guess wildly. for example i am guessing, you are using out of date gpu drivers, selected wrong gpu acceleration for rendering and/or preview and the wrong render profile in general.

i still dont see the need to capture in those high frame rates... (beside it says in OBS variable and not constant). why not just record in 60fps constant?
and since you just dont give us real information about your system, the vegas settings and what render profiles you are using, we can guess wildly. for example i am guessing, you are using out of date gpu drivers, selected wrong gpu acceleration for rendering and/or preview and the wrong render profile in general.

My GPU drivers are up-to-date, there is only one GPU acceleration option because I have no iGPU (very clear in the SPECS that I posted) and I am using AVC with a high bitrate.

considering that h264 (avc) is officially not for 4k 120fps, that is most likely an issue here https://de.wikipedia.org/wiki/H.264#Level

you also give it a try with h265 (hevc) encoding if you still want to keep that 120fps 4k stuff

what i can suggest is, try voukoder for encoding.
https://www.voukoder.org/forum/thread/783-downloads-instructions/
(the software itself and the plugin for vegas 20 in your case)

Rendering with the built in HEVC codec yielded the same result, but using Voukoder successfully rendered the video with all of the right settings. I appreciate your help and will continue to use it!

I've tried rendering it normally and waited 2 hours to get the result of a file rendered without GPU acceleration and no luck

That's the interesting bit, your CPU encode got the same problem, so unrelated to hardware encoders?

your CPU encode got the same problem, so unrelated to hardware encoders?

Yep, seems like it. It's odd but I'm going to stop watching this post now.

Just curious why would anyone wanna render a 4K 120P. I thought the purpose of having a high frame rate footage is for slow mo only.

@BruceUSA HIs onscreen info shows his game giving him 138 unique frames per second so if he captures and renders at 120fps he will get a almost lifelike representation of his gameplay for him or friends to watch locally.

He could send those videos to people, or host on an upgraded gaming discord at whatever fps he wants, or hosting sites that provide a player but use your encode, it doesn't re-encode. Here is an example using a video I conformed to 120fps, https://videy.co/v?id=nm8IjVP3

If you have a 144hz monitor you should see 120 unique frames per second, unless there's a limitation to how quickly browsers or the player updates.

@BruceUSA HIs his onscreen info shows his game giving him 138 unique frames per second so if he captures and renders at 120fps he will get a almost lifelike representation of his gameplay for him or friends to watch locally.

He could send those videos to people, or host on an upgraded gaming discord at whatever fps he wants, or hosting sites that provide a player but use your encode, it doesn't re-encode. Here is an example using a video I conformed to 120fps, https://videy.co/v?id=ijpMvUq0

If you have a 144hz monitor you should see 120 unique frames per second, unless there's a limitation to how quickly browsers or the player updates.

@todd-b Thanks for the explanation. :)