The documentation for AACS and the CodeEditor.
Fades in the currently playing music.
|Duration||Number||The amount of miliseconds it takes to fade in the music.||✓||1000|
If you pass an empty parameter as
Duration, it will default to one second (1000 miliseconds).
The minimum is 10 miliseconds. If you use a value lower than 10, it will be considered as 10. The only exception is 0 miliseconds, which are treated as instantly.