http://stackoverflow.com/questions/1019036/how-to-create-a-virtual-printer-in-windows

https://support.office.com/en-us/article/Command-line-switches-for-PowerPoint-2007-and-the-PowerPoint-Viewer-2007-205f1460-098e-42ba-bc6c-310a43d8a2cc

https://bazaar.launchpad.net/~openlp-core/openlp/trunk/files/head:/openlp/plugins/presentations/lib/

http://www.pptfaq.com/FAQ00517_How_can_I_make_Acrobat_PDFs_from_PowerPoint-.htm

https://superuser.com/questions/641471/how-can-i-automatically-convert-powerpoint-to-pdf