Video levels for DCP

[Xavier Plagaro]

Hi!

I have finished editing and color correcting a documentary. We have been taken in several festivals which ask us a DCP. I never did a DCP before. Our documentary is 108025p and since we are in Europe I think I will make the DCP 25fps.

My big doubt is video levels. In FCP X, I have all my levels between 0 and 100 IRE in the waveform monitor. Is this correct? Most skin tones are around 50IRE, is this OK??

Thanks for the creation of this wonderful software and for this forum.

[Carsten]

Did you use a calibrated rec.709 monitor for grading?

The only common issue regarding black levels is usually the question of video vs. data levels, espcially since Resolve offers these two ways of representing image data. Typically, most video file formats, like Quicktime/MP4/Prores, DNxHD, etc. use video levels, but you can force these formats into using data levels. Some people think that in order to preserve the widest possible dynamic range, especially towards a cinema DCP, they should use data levels. Basically, both do work, but you need to make sure that these levels are correctly interpreted in the color conversion of the DCP creation process. DCP-o-matic has a setting to choose video vs data levels now (beginning with 2.15). DCP-o-matic also has it's own waveform monitor where it is usually quite easy to spot video vs. data levels misinterpretation.

Very often, using an image sequence as a master for the DCP conversion is the reason for wrong black level interpretation. Most still image formats like TIF, JPEG,BMP, etc. use data ('full') levels per default. I have seen very many shorts and ads that went through OpenDCP for DCP conversion. OpenDCP only allows image sequences as the source, so, users are forced to use an image sequence export before they create the DCP. OpenDCP has no function to adjust for data vs. video levels itself, so many of these DCPs ended up with lifted black levels, because the wrong levels were written into the image sequence. That is no fault of OpenDCP, but of the user not understanding these issues, and the lack of means to recognise and correct it.

This is a typical example of lifted black levels because of data vs. video level misinterpretation:

Daniel Freund.png

I don't think you need to be concerned that much about luma levels, if you used a properly calibrated rec.709 monitor. Luma Levels should be where they belong. Just load a piece of your content with deep blacks into DCP-o-matic and check black levels in the video waveform monitor.
As a rule of thumb, if they go below 512, you should be fine. If they end around 512, the interpretation is probably wrong.

Note: You don't need to use 2.15 beta to get black levels right (betas are not advised for production work). If you can control the source, or if you see correct black levels in the wave form monitor, 2.14.x delivers exactly the same result. 2.15.x would be needed if you have footage with ambiguous black levels and no control prior to DCP conversion. 2.15 can also be used just for a quick check how the video vs. data levels setting affect the video waveform monitor output.

If you are concerned about your color grading, always check your DCP in a commercial cinema where you can assume the projector has seen a proper calibration.

[Xavier Plagaro]

Carsten, thanks for your deep and easy to understand answer!

My monitor is 709 calibrated, I hope there won't be any problem. Lifted black levels are pretty bad to see!