Cosmin Hodiș-Mîndraș wrote:It seems that every "QuickTime gamma bug" is experienced by people expecting QuickTime player and YouTube to look like Resolve's color viewer. Those producing for broadcast are always concerned about calibrated Rec709 professional monitors, fed by UltraStudio or DeckLink cards, and care little for computer displays. Fair enough. The thing is, I really want my YouTube uploads to look as close to Resolve as possible, even if some of my productions are intended for broadcast.
So I made a few tests, exporting QuickTime files from Resolve using several timeline color spaces. The result, as shown by macOS finder, are:
- Rec.709 Gamma 2.4 - Color profile: (1-2-1)
- Rec.709 Gamma 2.2 - Color profile: (1-4-1)
- Rec.709 (Scene) - Color profile: HD(1-1-1)
- sRGB - (1-13-1)
(What 1-1-1 or 1-2-1 mean is explained in the first post of this topic).
Any of those files, once exported from Resolve, looked different in QuickTime. Once uploaded to YouTube, those files looked different as well, low contrast and desaturated. I downloaded them from YouTube and every file had the same color profile: HD (1-1-1). The same happened when I compressed the files using HandBrake, the color profile was changed to HD (1-1-1) as well.
What's quite clear at this point is the fact that YouTube ignores the source color profile, assuming 1-1-1. So, as a consequence, I have to Cosmin Hodiș-Mîndraș.709 (Scene) in Resolve (because it exports 1-1-1 profiles), and color grade for it. But how to set Resolve to look like QuickTime Player? Enabling "Use Mac Display Color Profiles for Viewers" in DaVinci Resolve helped a bit, but not a lot, some shadows were crushed and definitely saturation looked different.
I then thought about creating a display LUT for Resolve, which mimics the QuickTime and YouTube output:
- I created a 1728x1728px 8-bit HALD image using ImageMagick:
- Code: Select all
convert hald:12 -depth 8 hald12_8bit.tif
- I imported the image in Resolve, setting the timeline color space to Rec.709 (Scene) and frame size to 1728x1728px;
- I rendered the movie using ProRes 4444;
- I opened the rendered movie in QuickTime, and made a screenshot (quite tricky, because I had to display the movie unscaled, and macOS Catalina shows no options on "Option+Scaled in Display Preferences for the built-in display; luckily I have an external LG UltraFine display that I could put in an unscaled mode - 5120x2880px);
- I cropped the screenshot and opened it in Lattice:
- I resized the LUT to 21:
- ... and I exported a .cube LUT.
After loading the LUT in 3D Color Viewer Lookup Table, QuickTime Player and Resolve viewer screenshots look identical, so I can confidently grade my timeline for YouTube, knowing that what I see is what I get.
But how about shots graded for broadcast, in Rec.709 2.4 timelines? Well, if broadcast is my main delivery and YouTube is second, I reversed the LUT in Lattice for a quick and dirty final "YouTube touch", essentially adding the "missing" saturation and contrast in one node just for YouTube delivery, on top of my main broadcast grade, temporarily switching the project to Rec.709 (Scene).
I'm not saying that this is a viable workflow for anybody. I'm quite sure that it works only on Apple's P3 displays; it's just an experiment, maybe a stupid thing to do, but the results are, for the first time (on my Macs) and at least for me, well, predictable again.
If anyone is interested, here is a link to the LUTs:
https://www.dropbox.com/s/0sux7nydfyk721w/Rec709_Scene_to_Mac.zip?dl=0