Cutting a beat or melody can be done manually or with an editor like . is capable of creating REX files and can also play any loop that is split on any sampler program.
This program is similar to any audio enhancement program. However, this program can only be used to detect volume changes and apply a noise gate to optimize the dynamics for any sound sample with a rhythmic basis (electric guitars, drums ,...).).
After marking the cutting points on your loop, you have options to either export them as REX files (ideal to use Reason's virtual instruments), or create MIDI files. This will allow you to keep a sample's groove.