See video, if you have Melodyne with Studio One you can get the tempo map, if not you can use the Audio Chord Wizard in RealBand to map out the tempo, then create a midi track in RealBand and open it with Studio One, then drop the source file in and it will align with the beats. You can then drop acidized files from Biab that will fit to the tempo map or you can change the map to a constant tempo.