MIDI/Instrument Loops by Marc Schonbrun
The other kind of loop is a MIDI or instrument loop. MIDI loops don't contain any audio information. Just like MIDI data, a MIDI loop only contains instructions to play notes. The actual sound is produced from a plug-in synthesizer. When you add a MIDI loop to your composition, the accompanying instrument track (which will be played back by a virtual instrument of your choosing) is created for you. Remember that MIDI doesn't make sounds on its own! While MIDI loops often sound as natural and realistic as audio loops, they also have some pros and cons.
Figure 7-3: Apple Instrument Loop
A MIDI loop is only as good as the plug-in that produces its sound. There are some great plug-ins that re-create instruments synthetically; there are also some bad ones. That's pretty much the only negative about MIDI loops. The biggest advantage to MIDI is that you can change the key and the tempo of a MIDI loop without consequence. Since a MIDI loop contains only instructions, there's no audio to stretch out; it just sends the command to play the note a bit later, or at a higher or lower pitch. MIDI loops are so much more malleable than audio loops. One really great thing about MIDI loops is that you can change them and make them your own. Take a look at this Apple Loop for GarageBand (Figure 7-3).
Once you double-click on the loop, it launches in the editor, where you can make adjustments. You can change any note you want, raise or lower the pitches, and change the duration of any of the notes.
How do I know if my loop is audio or MIDI?
In GarageBand, for example, audio loops are blue and MIDI loops are green. Each software is different, but it should show you clearly which loops are audio and which are MIDI. Check your program's manual or help section for assistance if you're not sure.
