I've tried Tachyon in Pixelstrings. There're no colorspace input for P3-DCI nor P3 in general
I thought it was a limitation in Alchemist only. Same issue with Tachyon. However, Rec.2020 is supported. I wonder if I should convert P3-DCI to Rec.2020 sources, apply the framerate conversion, and then reverse the colorspace from Rec.2020 to P3-DCI. But I'm not 100% sure the colors would stay intouched.
What would you suggest, Andrew?