The list of audio file formats that Ardour can import/embed is quite long. It is based on the functionality offered by libsndfile, an excellent and widely used software library by Australian programmer Erik de Castro Lopo. As libsndfile's capabilities expand, so will Ardour's abilities to import (and export) new formats. Ardour supports all common audio file formats, including WAV, AIFF, AIFC, CAF, W64 and BWF. with all typical sample formats (8,16,24,32 bit integer, floating point, and more).
You can find a full list of libsndfile's supported formats here.
For MIDI import, Ardour will read any Standard MIDI Format (SMF) file.