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Slog workflow with Multibridge+FinalCut

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Hernan Caratozzolo
Slog workflow with Multibridge+FinalCut
on Sep 6, 2008 at 12:14:19 pm

Hi,

I had the opportunity to shoot some material with Sony CineAlta with Slog. I capture it using a MacPro 2.8 8 Core 10.5.4 , 16GB RAM / 320GB+4x1TB RAID 0 / MultibridgePro2 (driver 6.7)/ FinalCutPro 6.0.4

Everything was perfect until we tried to export the plain capture to DPX files via FrameLink. All DXP had clipped whites.

Should I load a LUT curve for the input in the Decklink Pref Pane before capture?

Can someone help me with this workflow?

I think is something I'm doing wrong because I tried to Export-->Quicktime movie with som text and the result was a 10bits RGB 444 Blackmagic .mov with the same problem.

thanks


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Agustin Goya
Re: Slog workflow with Multibridge+FinalCut
on Sep 8, 2008 at 5:33:56 pm

Do you have material S log inside final Cut? If that's the case, you should export as DPX for grading, you don't need to apply any lut, again, only if what you have inside FCP is log (low contrast and saturation) I don't know how does the LUT works on Decklick capture, but I think that if you apply it to the capture you'll linearize the information loosing the advantages of log resulting in white clipping.
hope this helps,
Agustin




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Hernan Caratozzolo
Re: Slog workflow with Multibridge+FinalCut
on Sep 9, 2008 at 9:55:28 am

Agustin

"Do you have material S log inside final Cut? If that's the case, you should export as DPX for grading, you don't need to apply any lut..."

We captured dual SDI HD without any compensation, so, I think I have log material in finalcut. I don't know why the plain export to DPX clips the whites.


As I always work with video (lineal space for me because I never touched any setting and I never saw nothing in finalcut to correct color space) I think we need some one to really know what happend when we export with framelink (plain export) or finalcut with con text applied.

Info about the material: 1920x1080Psf 23.98 Blackmagic 10 RBG 4:4:4 with SLog and Hypergamma

Thanks for your time.



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Agustin Goya
Re: Slog workflow with Multibridge+FinalCut
on Sep 11, 2008 at 4:17:00 pm

If the image you captured looks washed out and without contrast and saturation, what you have is LOG. If you are completely sure that what you are editing have been shot S Log and you have Clipped whites inside FCP instead of a washed out picture, somewhere in the middle the image has been linearized and you have lost all the advantages of the S LOG curve.
If what you see inside FCP is washed out and when you export you get clipped whites then FCP is doing something wrong with the gamma.

Are you in an RGB or YUV sequence?
Which codec are you using to export?
The codec you are exporting is RGB or YUV?

hope this help.
Agustin



http://www.imdb.com/name/nm2339496/
http://www.wancamp.com.ar/digilab/


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Hernan Caratozzolo
Re: Slog workflow with Multibridge+FinalCut
on Sep 12, 2008 at 10:16:05 am

Thanks Agusin,

Yes, the image looks washed.

But not only FinalCut is doing something wrong (linear). Framelink, when you try to make DPX from the captured clip, has the same problem.

Answers:
Are you in an RGB or YUV sequence?
we used Blackmagic 1080p23.98 RGB 4:4:4, In this case the process tab in sequence settings is dimmed
Which codec are you using to export?
same as captured. When you export your sequence without post, it is all right. Add some text and you can't export with he same quality.
The codec you are exporting is RGB or YUV?
Allways RGB

Thanks again Agustin.







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Agustin Goya
Re: Slog workflow with Multibridge+FinalCut
on Sep 12, 2008 at 3:27:18 pm

Then FCP is doing some colorSpace/gamma conversion when rendering/exporting try exporting the same shot using different codec ANIMATION (RGB) and BLACKMAGIC (YUV), then compare if the ouput looks the same when imported in FCP and when opened in QuickTime.
You are not the only one suffering this issues, it definitively looks as a Final cut problem if i'm not mistaken.
hope this info help a little.
agustin





http://www.imdb.com/name/nm2339496/
http://www.wancamp.com.ar/digilab/


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Agustin Goya
Re: Slog workflow with Multibridge+FinalCut
on Sep 15, 2008 at 11:11:51 am

Hi Hernan I've found some information that I think It might help you.
FCP can only render a limited amount of effects in 10 bit color, and if you choose one which is not capable then it will truncate your color information to 8 bit with no warning. In particular only the the Cross Dissolve transition can render in 10 bit color, any other transitions and wipes will truncate color data, of the other effects included it’s hit and miss. See pages III-241 and II-389 of the FCP manual for a full list of which transitions, effects and filters can render in high precision. Maybe this is the reason you are having clipped information when rendered.


http://www.imdb.com/name/nm2339496/
http://www.wancamp.com.ar/digilab/


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