Creating Perfect Loops
Creating suitable loops is an art form in itself. So now that you know how important looping is, how do you do it?
Looping often starts in a DAW. Loops are self-contained audio regions, that are sourced or recorded and then cut, trimmed and tested to make sure they do not skip. It is a good idea to test your loops in a stereo editing program like Sound Forge or Adobe Audition after you bounce them out of your DAW to make sure that your ear is not being fooled and that they are in fact seamless.
Be patient—sometimes it can take a while to find a seamless loop point, you may find yourself blowing up the waveform to quite an extreme degree in order to find a suitable zero crossing point. What’s that? Well, a sound waveform graphically goes up and down around a center point of no volume. A seamless loop can most likely be created when the end of the loop and the beginning of the loop cross the exact center of the waveform where the volume of the wave is essentially zero. This is known as a “zero crossing” and it is vital to avoid clicks and pops. If you’re only selecting a loop of a few waveform cycles you can visually see the beginnings and endings of loops easily on the screen. However, for longer loops you may need blow up the waveform view to a more extreme magnification. Then you will set your loop markers, listen, and gradually change your marker points until a suitable zero crossing is found.
In some cases, it may be necessary to fade the waveform in or out, or you may also need to redraw the very end point of a wave file to avoid that pop or click. The length of the fade in/out will depend greatly on the situation. If you’re trying to create the best example of a continuous fan hum or an ominous turbine sound in an engine room then you may be reducing the length of your fades to mere milliseconds in order to avoid an obvious sense of the sound fading in and out. In other cases, some effects may have a pulsing component where they rise and fall naturally or regularly and this can be taken advantage of when designing your loop. Loops can be tricky and sometimes it takes a little bit of practice to get them right, but it’s really worth it to get it right before you send it out the door!
Excerpt from The Essential Guide to Game Audio:The Theory and Practice of Sound for Games by Steve Horowitz and Scott R. Looney © 2014 Taylor & Francis Group. All Rights Reserved.