NPK is a waveform image file format used by n-Track Studio software. NPK files don’t store any actual audio data, only information about given tracks. The purpose of NPK files is to a quick preview of given audio track on a timeline.

NPK files are generated automatically upon importing or recording an audio track. Even if a NPK is deleted by accident, it will be automatically recreated by the program upon restart. All the critical project data needed to generate waveform files is saved along with audio tracks