Something like this is probably a good starting point:
ghostscript -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/printer -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf
From this gist https://gist.github.com/guifromrio/6390547#