[In this specialized audio article, originally published in Game Developer magazine in 2008, LucasArts' Jesse Harlin discusses crossfading and shaping for good music edits.]

Rarely in the world of game scoring do pieces of music appear as they were originally written. Whether edited to loop, or for interactivity or content, a big part of preparing music for implementation is the process of additive or subtractive music editing. There isn't much middle ground with music editing. Bad edits are glaringly obvious and unmusical while good edits are completely undetectable.

The Basics of Blending

The simplest way to edit two pieces of music together is by using a basic crossfade at the join. Music which uses the same time signature and at the same tempo (which is the case for most pop/rock music as well as most game scores) is the easiest to tackle with basic crossfades.

Simple crossfades have a number of benefits. All digital audio workstations (DAWs) such as Pro Tools or Logic make authoring crossfades easy with click-and-drag crossfade tools.

These tools offer a limited ability to edit the shape of the fades, though editing one part of the fade will affect the entire crossfade curve. Additionally, simple crossfades lack the dangers of radical changes in amplitude that come from more advanced edits such as layering multiple tracks together and summing their outputs.

The size of a crossfade depends on what's going on musically at the join. If you're simply editing out a verse from a pop tune, the crossfade will most likely be fairly short and centered on a moment of identical orchestration, such as a repeated guitar riff, or you may splice together a syncopated drum accent.

Crossfading between arrhythmic pads or long decay tails will most likely benefit from longer crossfades that approximate the dovetailing of one completed musical thought and the beginning of a second thought.

Crossfading of multiple tracks in Logic is shown.

Simple crossfades can have their problems, as melodies that don't begin on barlines or long cymbal swells are more difficult to tackle with a simplified crossfade tool. In these cases, the join of your edit will probably not be the center point of the crossfade.

Rather, you may find the fade beginning a few beats before or ending a few beats after the join in order to ease into or out of sections with troublesome instrumentation or lingering high frequency noise.