Visual Artifacts After Rendering to MP4

Hi,

I am a novice with Davinci Resolve and running into an issue with 16.2.2. My video has visual artifacts after being rendered. Video looks great within Davinci, but once it is rendered it has blocks showing briefly in 2 areas of the video that make it unusable. Using the free version. I've never run into this problem before. I'm recording in OBS with an MP4 output and I'm rendering from Davinci Resolve to MP4. I've updated my Nvidia GPU driver and tried different render rates/settings. I've cleared the cacheclips and tried *turn it off and turn it back on. Nothing seems to help. I've also tried rendering to Qwiktime format. I will try to include some snippets today as well.

Resolve's native software H264 encoder is not great. Use NVENC if you can, or export to Cineform and use FFMPEG.

I disagree with Peter. I find the software encoder both superior in quality to the hardware encoding and of sufficient quality to use for deliverables.

I'm recording in OBS

I always recommend hardware recorders for screen capture you intend to edit. They typically offer editing friendly options like DNx and ProRes, whereas software normally doesn't.

https://www.blackmagicdesign.com/produc ... ideoassist

OBS does offer any format, as it can just pipe to FFMPEG. So you can record to ProRes if you wish. I'd use NVENC all intra 444 lossless H264 in OBS to feed to Resolve. ProRes still seeks a bit fast, but not much.

What is the bitrate of the video you are using in Resolve? If using h264 with a lowish bitrate and there are dark and noisy areas in the picture, they will tend to show blocking artifacts.

ProRes still seeks a bit fast, but not much.

Could you explain what you mean by this? I'm a newbie to ProRes and other such formats and have been wondering if I should be using them in future - eg recording from OBS to ProRes, as discussed here, instead of always using h264.

One reason I've used h264 thus far is that my CPU is 10 years old and has trouble keeping up with software encoding - at least it does in h264. But I hope to be getting a new modern system in the next month or two.

Your issue is export encoding in Resolve, not original encoding in OBS. I'd use mp4, h264, Nvidia, Constant PQ, Best, lookahead 32 if you have a Nvidia card and the Studio version.

Else export it to to Cineform from Resolve and use FFMPEG with similar settings.

ProRes and all intra H264 are just faster to edit/seek for Resolve. But that doesn't seem to be your issue.

I'm not the OP, I was just interested to understand that comment you made regarding ProRes.

Now I see your further message, I understand that in the line I quoted you had meant to write "ProRes still seeks a bit faster". I posted because I was confused about what you might mean by ProRes being a bit 'fast', as if it was suggesting there was some issue with ProRes.

All cleared up now

The video bitrate is 2500 Kbps from OBS.
Game plan is to optimize OBS output, then optimize Davinci Resolve render settings to prevent future issues. I changed the encoder for OBS from software x264 to Harware QSV (thoughts/suggestions?). I don't see FFMPEG as a settings option in OBS.

For Davinci Resolve I set the export to mp4, h264, my GPU is Nvidia, but I'm not sure how to set Constant PQ, lookahead 32, and I am using the free version. Still researching...

Use "NVENC new" in OBS if your GPU is Nvidia. Constant PQ, 18-24, bframes 4.

You need to switch to advanced. FFMPEG is under advanced - custom, but no need for it.