Are these inter frame artifacts? (gamma, ghosting, repeated lines)

[Chris Tucker]

Hello, I shot a scene with my Nikon D3300 and edited it on my Mac with FCPX. It looked fine to me during editing, but when it was shown at film club via a small projector, some people noted the blacks weren't sufficiently black, and that also the man walking off the frame to the right appears to be partially transparent, as if a ghost.

Have a look here (youtube, 18 seconds.)

The original video was shot in HQ video mode, 23.98 fps manual exposure, H.264 codec. (The youtube version here took the original video, shortened it, made three copies, each successively lighter so as to make the problems more apparent, exported as Prores 422 and uploaded to youtube.)

The Mac, a 2015 Macbook Pro, is set to the default "Color LCD" profile in the System Preferences which I've read is a gamma of 2.2 (?). I've read FCPX uses a 2.4 gamma. The FCPX project was set to Rec.709 and the movie was exported to an h.264 file (which was then displayed on the projector at the club meeting.)

I was thinking of running tests next time I'm near the projector by using it to display some pluge and color bar charts to check its calibration, and to perhaps adjust my Mac to match. (I'm not sure if I can adjust the projector settings myself, as it belongs to a university, thus I am interested in making changes on my end to fit what works best on the projector.)

I think what happened is there was perhaps a gamma mismatch between my Mac's screen and the projector. When editing on my Mac, the image was dark enough that I didn't notice the ghosting. But when displayed on the lighter projector, the ghosting was light enough to be seen.

I also wonder if the shutter speed might have caused some of the ghosting, as I normally shoot at 1/50th or higher but I might have gone down as low as 1/25th during that particular shoot -- I don't recall. Perhaps that's just too slow a shutter speed and it resulted in some or all of the ghosting effect?

Any thought on this ghosting/gamma issue?

Second issue:

I also noticed repeating lines such as when one character moves his hand, and when the other man moves his leg (see attached photo). The lighter portions of the arm and leg are repeated in subsequent frames. I suspect this is due to the inter frame codec the D3300 uses but I'd like to get confirmation on that. Presumably if I had a camera with intra frame codecs, this would not be a problem eh? I don't think the problem is severe enough that I'd bother to spend money to do anything about it. It's not usually noticeable.

Thanks! Chris.