Logic Pro 9 User Manual - Help Library - Apple

Because one-shots are handled like normal audio files, the usual stereo or mono region
symbol is shown alongside the filename (rather than the Apple Loops symbol).
If you want to create a looped Apple Loops file from an audio file that does not match
the project tempo, you should use the Apple Loops Utility. The Apple Loops Utility allows
you to define the intended length of the loop, regardless of the project tempo, by manually
setting the Number of Beats and Time Signature tags.
Note: The Apple Loops Utility only works with audio regions—not with MIDI regions on
instrument tracks. For further information, see Creating Apple Loops in the Apple Loops
Utility.
Adjusting the Project Tempo to an Audio file
You can also adjust the project tempo to the file length. Logic Pro offers an automatic
function that matches the length of an audio region with the intended musical length.
The length of the region remains constant, but the sequencer tempo is varied
automatically, with the region playing back at the intended length. For full details, see
Setting the Project Tempo to Match an Audio Region.
Re-creating Effects in Software Instrument Apple Loops
If you create a Software Instrument Apple Loops (SIAL) from a region on a software
instrument track that uses sends to bus effects, and then drag the saved loop to another
(empty) instrument track, the new loop will sound different from the original source
region. This happens because the effects sends in the original track are not saved with
the loop.
Logic Pro does not automatically assign effects to busses, because doing so would
potentially interfere with bus configurations that you’ve already set up in your project.
Effects that are inserted directly into the software instrument channel strip will, however,
be automatically recalled when the loop is dragged into the Arrange area from the Loop
Browser.
852 Chapter 30 Creating Apple Loops