Envelope Loops (LPM)
An Envelope Loop (abbreviated LPM) is an audio file that can contain three different "sections" of audio:
The beginning of a sound.
A looping middle of the sound.
The end of a sound.
These different sections are defined by special loop point markers saved into the audio file.
There are two kinds of envelope loops in the Creation Engine.
Fast Envelope Loop
Loops between two set points in the sound and immediately jumps to the release when told to stop.
Slow Envelope Loop
Loops between two set points in the sound and plays through to release when told to stop.
How to Create an Envelope Loop
Assemble Your Sound
To create an envelope loop, I recommend bouncing your three sounds ("start", "loop", and "end") separately, then combining them in a multitrack so that the loop sits cleanly between the start and end. Crossfade your loop underneath the start and end so that it naturally ramps in and out.
Embed the Loop Points
Creation Kit will only recognize your envelope loop if loop point markers are embedded in your wave file. Not all DAW's are capable of writing these loop points in the correct format (for instance, iZotope RX marker regions don't work, but Steinberg WaveLab Looping Regions do work).
The technical term for these embedded loop points is a "SMPL" data chunk, or Sample chunk. You can read more about it here.
If your DAW can't write loop points in the correct format, no worries, we can use the free application Wavosaur (Windows only) to add the loop points. Before you leave your DAW, add markers to precisely where your loop should begin and end. You can use these markers later as reference when setting the loop points in Wavosaur.
How to Set Loop Points with Wavosaur
1. Install Wavosaur: https://www.wavosaur.com/
2. Select your desired loop region.
3. Go to Tool -> Loop -> Create Loop Points. (or press L)
4. File -> Save (Ctrl + S) to embed your looping points into the wave file. Done!