GarageBand for Mac: Import audio and MIDI files
You can import audio files of the following file types into a GarageBand project:
AAC (except protected AAC files)
You can also import MIDI files into a GarageBand project. MIDI is a standard file format for synthesizers and other electronic music instruments. MIDI files don’t contain recorded sound, but do contain data that electronic instruments can use to produce music. MIDI files are available online and can also be exported by many popular music software applications.
Import an audio file from the Finder
Drag the audio file you want to import from the Finder to an audio track or to the empty area below the existing tracks in the Tracks area.
The audio file appears on the track.
Import a MIDI file from the Finder
Drag the MIDI file you want to import from the Finder to a software instrument track or to the empty area below the existing tracks in the Tracks area.
The MIDI file appears on one or more software instrument tracks. You can choose the software instrument used to play the MIDI file in the Library.