Saturday, February 20, 2021

Re: [Avid-L2] IMF DolbyVision Metadata version mismatch in Resolve?

I was taught at HDR class to set the hdr ref monitor to Rec 2020 for grading then in the end limit to P3 to meet Netflix delivery spec.  HBO Max and others seem to want Rec 2020.  The Netflix choice was because there is too much difference in monitor display in Rec 2020 because, as has been pointed out, no monitor really achieves true Rec 2020 so by pushing the display limits there are a lot of difference in HDR Rec 2020 ref monitor image between the various ref monitors.

I got some info from a contact I have at Dolby that confirms some of the info in this thread regarding how to check the DV metadata:
"You can check the embedded metadata in the IMF using the Dolby Vision Professional Tools which comes with the Dolby Vision annual license. You can also check it on a system like MTI Cortex or Colorfront Transkoder.

 The images may be rendered in Rec2020 but may have been graded/mastered using a P3 reference display. This is common in workflows where the colorist prefers to work in P3 but has to deliver Rec2020 to the studio/client."


Here is a bug that might explain what I'm seeing.  This was told to me by a different facility that has master several of our HDR projects.  I think this is probably what happened.  The facility that created the IMF I'm dealing with now was new to HDR workflow from the Resolve side.
"..., if you make an IMF out of Resolve with your output colorspace at Rec 2020 and limit your gamut to P3, the Dolby metadata it embeds in the IMF incorrectly says that the media is encoded with P3 color primaries (which will cause a major color shift) even though the mastering display is correctly labelled as Rec 2020. It does not do this when outputting a DoVi XML. Creating the P3 limited output first, and then making the IMF from it gets both the image data and embedded metadata correct (albeit with a bunch of extra steps)."


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