rasterizing/”setting” a pdf

I don’t recall running into this before, but I was trying to print a pdf that displayed fine on my computer (firefox, okular), and the printer failed on the 8th page w/

ERROR:
typecheck
OFFENDING COMMAND:
known

which is apparently some postscript error or incompatibility with the printer.

    pdf2djvu -d 1200 input.pdf > output.djvu

I don’t know how low for density (<300?) is too blurry or too high unnecessary (>1200?)

    ddjvu -format=pdf output.djvu output.pdf