[wesk05]

Yep. RGB is correct. Just the YCbCr selections are mangled. Curious that they would use the correct matrix for 2K output, then fall back to BT.601 (or something) for 4K.
I look forward to your results, time permitting.

I brought up the matrix issue only to explain the odd results that I got with my test pattern that didn't have proper SEI data. I haven't come across any problem with 8-bit 1080p content to 4K upscaling or chroma upsampling.