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random bars appear across top or bottom of frame in Resolve 12 project
Hey folks.
I’ve just been cutting a stop-motion project in resolve 12 (lite). Every so often, there is a narrow bar superimposed across the image, top or bottom of frame. Sometimes it is pure noise, sometimes is seems like a crop from elsewhere on the screen.
The bars appear at random places along the timeline, popping up successively during an edit session. ie there are none at the start of a session, and like a cancer, a few have appeared by the end. They appear in the rendered output.
If I restart Resolve, the bars are gone, possibly to return in new places.The footage I’m using is a series of JPGs generated by a stills camera, roughly 4k dimensions, sRGB. I started this project using DNG stills, but replaced them with the JPGs because I liked Adobe’s conversion better than resolves. To be clear, the JPG version is actually a fresh project file, but the issue appeared in both project files (DNG and JPG versions).
My system is a 2014 27″ imac with decent spec (though the base level GPU).
Anyone know what on earth I’m talking about, or even better, how it might be avoided?
The attached image a screen grab of one of the bars.
Mathew Farrell
flowstate.com.au -
3 Replies
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Seems like a GPU failure, or it is a CPU decoding deficiency. The iMac is not particularly well suited to above-HD resolutions, and you have loaded it down with a fairly heavy media extraction task. While most grade software has evolved from .cin and .dpx sequential image formats, the original hardware platforms were Linux/Unix servers. Commodity-level PCs seem to deal more readily with .mov formats, with the best compromise centering around intra- flow codecs like ProRes and DnX — and this seems to be a defining difference between producing motion media as an animation/photographic methodology vs. a cinematographic one.
jPo, CSI
“I always pass on free advice — its never of any use to me” Oscar Wilde.
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Cheers Joe, I only just saw your reply.
Mercifully I got the project out the door cleanly. I’ll do a bit more experimenting to see if I can break it again and try and predict the behaviour.
Such a shame the imac is a locked box w.r.t. video card. It would be great if we could loop out to a better card.
Mathew Farrell
flowstate.com.au -
I’m seeing the same thing. It seems to happen with only certain types of transcodes. As I recall, conversions to MXF/ OP1A DNxHR. The problems seem to have started with Resolve v12.5, as I never saw this before that version, with the same kinds of outputs. BTW, I’m on a PC not a MAC.
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