Convert PDF to MIDI

There are several utilities capable of importing Adobe Portable Document Format Files containing sheet music and exporting those to numerous formats, including MIDI Music Data Files (.pdf to .midi conversion). 

Such attempts will only be successful if your PDF documents actually contain music data, typically exported from music notation and composition programs.

A viable alternative would be using an optical music recognition (OMR) solution, such as SharpEye Music Reader, which would be capable of recovering sheet music from images or PDF documents.