Blackmagic Forum

I have a 2160p timeline that always has corrupt regions in frames in exactly the same spot (bottom left of frame) when I render it to a 2160p format. The corrupt regions do not appear when rendered to 1080p or 720p. I'm attaching an image that shows what I'm seeing. This corruption shows up during a segment of the timeline that is supposed to be a black screen following an abrupt cut from other video.

How do I get rid of these errors in the 2160p version?

[EDIT] It appears you have to scroll down to see the corrupt region in the display window that was added to this post.

Thanks,

rgames

Is that 'black' coming from a Solid Color Generator, an empty space in the timeline, or just a dark part of a video clip?

List out your hardware and media specs.

If everything else but resolution is the same, that points to GPU overload.

Jim Simon wrote:Is that 'black' coming from a Solid Color Generator, an empty space in the timeline, or just a dark part of a video clip?

List out your hardware and media specs.

The black is from empty space in the timeline. But there is an adjustment layer above it - maybe I need to try removing that. Specs are 14-core i9, 128 GB RAM, RTX 2080 video card, bunch of SSDs and a few HDDs. Media is a mix of 10-bit and 8-bit H.264 from Sony A7s iii and a6600.

Regarding GPU overload - how do I get around that problem? Is there a software rendering option?

Thanks,

rgames

Update - I rendered it using the NVIDIA encoder and the corruption does not appear. However, the NVIDIA encoder seems to be slightly lower quality (other than the corrupt frames of course) so I'd prefer to use the native encoder. I also tried removing the adjustment layer but the corruption still appears when using the native encoder for export.

Also, forgot to mention in the original post - the corruption does not appear when I play the video preview within Resolve, though I'm set up for HD previews so I guess that's not surprising.

Regarding GPU overload - I checked and never got above 5.7 GB of GPU RAM usage using the native export so it seems like there's some headroom there (there's 8 GB available). When I used the NVIDIA encoder the GPU RAM usage went up to 6.1 GB and, of course, there was a lot more GPU processing activity.

So even though there's a lot more GPU usage using the native encoder the corruption does not appear. So it seems like it's not a GPU limitation (right?) and is, instead, something specific to Resolve. Though I'll admit I don't completely understand how Resolve uses the GPU so maybe my reasoning is flawed. But from what I can see the GPU is much more heavily loaded using the NVIDIA encoder and it does *not* produce the corrupt frames.

Thanks again,

rgames

Try to export in a high-quality codec like DNxHR or Cineform and then encode to H.264 or 265 with Handbrake. It's higher quality anyway and you can keep a master for the future.

rgames wrote:The black is from empty space in the timeline.

OK. Try filling that in with a Solid Color. Report back.