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Color stripe appears on some frames in exported video

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Fay Gartenberg
Color stripe appears on some frames in exported video
on Nov 27, 2018 at 6:36:39 pm

I am working in Davinci Resolve Studio 15 on a 30 minute TV episode. The footage is RED RAW 6K. When I do an export to H.264 1080 HD, I have noticed horizontal color stripes that appear for just a frame. I double checked my timeline and the source footage looks totally clean so it seems something is happening on export. I have included screen shots here of my export settings, the timeline, and the frame itself where the stripe shows up. Any idea why this might be happening? Thanks!









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Tero Ahlfors
Re: Color stripe appears on some frames in exported video
on Nov 27, 2018 at 7:37:16 pm

Are you, by any chance, using a trashcan Mac Pro?


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Fay Gartenberg
Re: Color stripe appears on some frames in exported video
on Nov 27, 2018 at 7:57:12 pm

Hi Tero,

Yes. I am working on a mac pro trashcan.


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Tero Ahlfors
Re: Color stripe appears on some frames in exported video
on Nov 28, 2018 at 4:25:28 am

This has been a problem ever since the trashcan was released. It was designed to look nice but they didn't care about the cooling so it'll overheat and you get some neat artifacting because of that. You can try a few things: if you're under warranty then try to get the GPUs changed, force Resolve to render slower or blast the machine with a fan while you're working to cool it down.


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Marc Wielage
Re: Color stripe appears on some frames in exported video
on Nov 28, 2018 at 6:45:29 am

You can use a free utility called Macs Fan Control to kick the fan up to 1800RPM, which will cool off the overheating GPUs.

In general, the steps are:

1) shut down and let the machine cool off for at least 30 minutes
2) reboot it and go directly into Resolve without launching any other programs
3) turn the fans off with Macs Fan Control
4) get the temperature no more than about 100-105° F
5) render at a slow speed (10fps or 4fps)

And this will sometimes work. Worst case, render out the material in segments to an intermediate format, then stitch those together for final delivery.

I had terrible problems with a 6-core a few years ago, but a second 12-core Trashcan has been very, very good at not overheating and causing glitches.


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Declan Smith
Re: Color stripe appears on some frames in exported video
on Nov 28, 2018 at 11:22:45 am

Interesting that I had a similar export issue but with Audio, i.e. short Pop at the beginning of an audio fade. When listening on the timeline, absolutely no problem, when rendered out to H.264, a glitch at the same place every time, even after clearing render caches etc. When I reviewed the ProRes master I created, no glitch. Maybe there is some issue with H.264 encoding in Resolve.

My computer is not a Trashcan Mac, it's a 2009 MacPro upgraded to 2010, 2 x 3.46Ghz Processors, 64Gb Ram, and an Nvidia GeForce-GTX Titan 6Gb GPU.

Declan Smith
http://www.madpanic.tv
Davinci Resolve / FCPX / Adobe CS6 / FCS3 / Zoom F8 / Roland R26 / Canon XLH1 / Canon 7D / Reason 10 / Cubase

"it's either binary or it's not"


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Marc Wielage
Re: Color stripe appears on some frames in exported video
on Nov 28, 2018 at 1:00:19 pm

[Declan Smith] "Interesting that I had a similar export issue but with Audio, i.e. short Pop at the beginning of an audio fade. When listening on the timeline, absolutely no problem, when rendered out to H.264, a glitch at the same place every time, even after clearing render caches etc. When I reviewed the ProRes master I created, no glitch. Maybe there is some issue with H.264 encoding in Resolve. "
My workaround for now would be to use the ProRes master you created (which is a good idea, BTW) and use another program like QuickTime or Adobe Media Encoder to make the H.264. If it's going to YouTube note that they re-encode a lot of stuff anyway, so you could just try uploading the QuickTime and let YouTube re-encode it for you.

I routinely upload ProRes LT to Vimeo Pro and Frame.io, and it looks fine to me. On Frame.io, they'll keep it in that native form without re-encoding for anybody who wants to download it (password-protected).


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