ffmpeg: How to list all possible video parameters for DNxHD dnxhr_lb profile?
The DNxHR profiles have simpler restrictions - only on pixel format and minimum frame size.

Accepted Pixel formats

LB:  YUV 4:2:2 (8-bit)
SQ:  YUV 4:2:2 (8-bit)
HQ:  YUV 4:2:2 (8-bit)
HQX: YUV 4:2:2 (10-bit)
444: YUV 4:4:4 or RGB (10-bit)

In addition, all HR profiles require the picture to be at least 256 x 120.