Though I am sure sneaker_ger's suggestions are good, I have had success with the following:
Code:
LWLibavVideoSource(<path>, stacked=true, format="YUV420P10")
## 'format' must match source; in this example,
## MediaInfo says "Chroma subsampling" = 4:2:0, and "Bit depth" = 10
ConvertFromStacked(bits=10) ## ('bits' must match format above)
ConvertBits(8, dither=0) ## '0' means on, '-1' means off