The best and quickest test is to measure video streamed patterns from inside ATV and then measure the same patterns via Rpi. (Your TV don't need to be calibrated, just use the default settings)So, now I'm more confused than ever.
For ATV 4K what is better?
- Set the ATV to YCbCr then make a calibration within infuse with Ted's patterns for SDR and Masciola for HDR ?
- Make a calibration in RGB with the Raspy > Set ATV to RGB and then maybe checking the errors with patterns within Infuse?
Compare then both reports and decide.