Video Clean Feed DRS 16.2 Q

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Paul Draper

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Video Clean Feed DRS 16.2 Q

PostWed Jan 22, 2020 11:22 pm

Any there any practical differences between using Video Clean Feed vs. (in my case) a DeckLink Mini Monitor 4k? I'm mostly editing 4k H.264 on a Rec.709 1080p timeline, via a calibrated BenQ SW2700PT Display.

Is it really worth keeping the PCIe card & instead fee up that slot or something else. To my eye, I don't really see any operational differences but I could well be missing something.

Thanks.
MacPro 7,1, 16 core, 2TB, 192GB, Vega II 32GB. UA Apollo x8, DeckLink MiniMon 4k. 8TB RAID 4 OWC Thunderbay 6, 2TB RAID 0 Sonnet M.2 4x4. Dell U3415W & BenQ SW2700PT. Nuendo, FCPX, Resolve Studio 16.2.
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Marc Wielage

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Re: Video Clean Feed DRS 16.2 Q

PostThu Jan 23, 2020 4:39 am

Paul Draper wrote:Any there any practical differences between using Video Clean Feed vs. (in my case) a DeckLink Mini Monitor 4k?

If the output is not color managed, then it's subject to whatever changes the operating system creates in the signal path.

Read pp. 2284-2285 of the Resolve 16.1.2 manual, the section titled "Limitations When Grading with the Viewer on a Computer Display." This goes into some detail why you cannot accurately monitor directly from the computer and operating system. You have to have a color-managed output, like one from a Blackmagic display card, preferably on a calibrated external Rec709 display. This also includes the so-called "Clean Feed" output mode. If the operating display can affect the monitor, it won't work for judging accurate color.

Even if the monitor is calibrated, color management is still vital. You can use the Clean Feed if you're just editing and accurate color quality doesn't matter.
marc wielage, csi • VP/color & workflow • chroma | hollywood
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peterjackson

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Re: Video Clean Feed DRS 16.2 Q

PostThu Jan 23, 2020 9:57 am

Windows doesn't do any global color management. So unless you're a Mac User there is nothing to worry with regards to OS based color management.

There is also nothing to believe or not believe here, just get your probe out and measure.

What you'll miss is probably 10bit output.
XPS 9750, i9-8950HK, 32GB, 2TB NVM, Intel 630, GTX 1050 Ti, 1080 Ti eGPU, Mini Monitor, BMCC4K. Versions: BIOS 1.7.0, Intel 630 24.20.100.6287, Nvidia 25.21.14.1881, Thunderbolt 17.4.77.13, Win10 Enterprise 10.0.17134.
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Marc Wielage

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Re: Video Clean Feed DRS 16.2 Q

PostThu Jan 23, 2020 10:08 am

peterjackson wrote:Windows doesn't do any global color management. So unless you're a Mac User there is nothing to worry with regards to OS based color management. There is also nothing to believe or not believe here, just get your probe out and measure.

For both Baselight and Resolve, they advise using an authorized video card to bypass the operating system color management. I think it makes sense for a lot of good reasons. Avoid my advice at your own peril -- do what you think is best.

One of the problems with asking for free advice on the internet is that sometimes, the answers you get may not be what you expected or hoped for. But it doesn't make the advice any less true.
marc wielage, csi • VP/color & workflow • chroma | hollywood
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Kenzo

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Re: Video Clean Feed DRS 16.2 Q

PostThu Jan 23, 2020 12:12 pm

Marc Wielage wrote:You can use the Clean Feed if you're just editing and accurate color quality doesn't matter.

And if you don't mind micro jams caused by the lack of vertical synchronization.
Setting the monitor to a frequency appropriate for the project helps, but the picture is not as smooth as from Decklink.
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peterjackson

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Re: Video Clean Feed DRS 16.2 Q

PostThu Jan 23, 2020 2:25 pm

Marc Wielage wrote:
peterjackson wrote:Windows doesn't do any global color management. So unless you're a Mac User there is nothing to worry with regards to OS based color management. There is also nothing to believe or not believe here, just get your probe out and measure.

For both Baselight and Resolve, they advise using an authorized video card to bypass the operating system color management. I think it makes sense for a lot of good reasons. Avoid my advice at your own peril -- do what you think is best.

One of the problems with asking for free advice on the internet is that sometimes, the answers you get may not be what you expected or hoped for. But it doesn't make the advice any less true.
Feed a color ramp through both cards and capture the output. Subtract both captures from on another and see if you got any non-black pixels. This is not rocket science.
XPS 9750, i9-8950HK, 32GB, 2TB NVM, Intel 630, GTX 1050 Ti, 1080 Ti eGPU, Mini Monitor, BMCC4K. Versions: BIOS 1.7.0, Intel 630 24.20.100.6287, Nvidia 25.21.14.1881, Thunderbolt 17.4.77.13, Win10 Enterprise 10.0.17134.
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Jim Simon

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Re: Video Clean Feed DRS 16.2 Q

PostThu Jan 23, 2020 3:17 pm

Paul Draper wrote:Any there any practical differences between using Video Clean Feed vs. (in my case) a DeckLink Mini Monitor 4k?


Short answer, yes. Using a dedicated I/O will bypass the OS and GPU driver, thus ensuring an accurate signal. It is still the only 'correct' way to monitor for Quality Control purposes.
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peterjackson

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Re: Video Clean Feed DRS 16.2 Q

PostThu Jan 23, 2020 4:12 pm

... for cargo cult people that cannot be bothered with reason and actual measurements, yes.
XPS 9750, i9-8950HK, 32GB, 2TB NVM, Intel 630, GTX 1050 Ti, 1080 Ti eGPU, Mini Monitor, BMCC4K. Versions: BIOS 1.7.0, Intel 630 24.20.100.6287, Nvidia 25.21.14.1881, Thunderbolt 17.4.77.13, Win10 Enterprise 10.0.17134.
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kinvermark

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Re: Video Clean Feed DRS 16.2 Q

PostThu Jan 23, 2020 4:51 pm

Do a forum search on clean feed to see further discussion. Short version: clean feed does not behave the same on every page in Resolve.

So for now, Decklink is safer option.
Windows 10 PC. Intel i7 x980, 24GB RAM, Nvidia 2070 Super 8GB GPU, SSD & RAID HD array. Dual UHD monitors. Decklink 4k mini. Resolve Studio 16.2

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