The supported formats differ, depending on how you use the DDJ-FLX4. Refer to the sources below for details, which might change according to updates.

■ rekordbox for Mac/Windows (Performance mode)

See [Music files that can be loaded and played (file formats)] in the rekordbox Instruction Manual.

You can read the rekordbox Instruction Manual [rekordbox.com].

■ rekordbox for iOS/Android
FLAC, ALAC, WAV, AIFF, MP3 and AAC.
Music files with DRM (copyright protection) or audio formats not supported by your mobile device can't be imported.

■ Serato DJ Lite

For details see the Serato DJ Lite manual, available from the Serato website [serato.com].