How good is Sony's XAVC-I codec when compared to ProResHQ?

[DougJensen]

Sometimes I hear people say that Sony's XAVC-I codec isn't good enough for shooting LOG and that they prefer recording  Apple's ProRes codec with an external recorder.  Using an external recorder for this reason always seemed like a huge waste of time and effort to me, but I'd never done a comparison between the two.  So I decided to do some tests between XAVC-I and the HQ version of ProRes.

XAVC-I @ 24 fps records at 240 Mbps while ProResHQ is over 700 Mbps. That means that (all other things being equal) a ProResHQ file will be 3x larger than the XAVC-I version. In other words, you can get 3x more footage on a memory card when you shoot XAVC-I. But do you pay a penalty in image quality when using XAVC-I? To answer that question, I decided to shoot a few test shots with my FX6 to see how the two codecs compared. I recorded XAVC-I internally onboard the camera while simultaneously recording the camera's 10-bit output via HDMI to a Blackmagic 5" Video Assist. In these split-screen tests, the XAVC-I version is on one side of the screen . . . and the ProResHQ version is on the other. Both were shot with the exact same camera settings (S-LOG3) and have had the same grading applied in post. Only very minor adjustments have been made in Resolve to fine-tune and match the Lift/Gamma/Gain. Can you tell which is which?