Messages

@HappyBlack
You can use the mv1080p mode from crop_rec. (3x3 binning)
You can get 3:2 1736x1158.
But if you really need 4:3 set the horizontal resolution in the raw settings to "1600" and you'll be able to get "4:3" 1600x1158. (crops in a bit)

Probably your best bets

@Danne
Did some 1x3 recording testing on the Jan17 build, and so far it seems promising.
I did about 5minutes+ of video clips in good light. (13 clips in total)
- Most of the clips came out without corruption.
- Some had 1 or 2 corrupted frames. (Still usable)
- 1 clip came out with a lot of corrupted frames. (I can't figure out why, but it was fixed after restarting the camera, so it's probably nothing)
- Sometimes gives a "frame order error" when recording.
Settings I used were your preset on 1x3, 10bit, 2.35:1, sd_uhs, 100 iso, 23.98fps and Preview set to framing (as you stated it may help)

Hope this info helps.
Getting really close!

I'm getting corrupted frames using 1x3 preset and sd_uhs with the latest build. (They happen here and there. "Purple glitch")
Any information I can give to help you try to solve it?
What exact settings did you @Danne use to get uncorrupted footage?