Pdf Import Extension/Current Architecture
From Apache OpenOffice Wiki
Currently, the PDF import extension utilizes xpdf for parsing the pdf file, and generating a bunch of low-level output operations to synthesize an ODF document.
This is a bit cumbersome, as xpdf is GPL licensed, which makes it necessary to run it completely out-of-process for OOo (being LGPL-licensed). A dedicated replacement parser is in the making (filter/source/pdfimport/pdfparse), will take some time to be on par with xpdf, though.
