Apple Logic Pro 7 - Manual (Page 339)

Chapter 8 Global Tracks 339
Note: If you want to draw a connecting line from a bar position to a particular position
of the original recording where no note exists, hold Control while drawing the
connecting line with the mouse. This will allow the line to snap to any format
subdivision.
Important: Beat Mapping is also possible in the Matrix, Score, and Hyper Edit windows,
where you have the additional advantage of directly seeing the corresponding notes.
Beat Mapping with Audio Regions
This works in a similar fashion to that described above for MIDI Regions. The main
difference is that Logic must first analyze Audio Regions in order to find rhythmically
prominent spots, which can subsequently be linked to a bar position. During this
analysis, Logic searches for transients: Positions where the audio recording becomes a
lot louder—over a very short time span (a signal “spike”, in other words). This is typical
of drum recordings, but the analysis of other instruments or complete mixes
(depending on the musical context) can also produce usable results.
To detect transients, select the Audio Region and click the Analyze button in the Track
List of the Beat Mapping track. Following analysis, the transients are displayed as small
vertical lines at the bottom of the Beat Mapping track, just like the notes in MIDI
Regions. The Beat Mapping procedure is as described above for MIDI Regions.
It is also possible to analyze several selected Audio Regions at once. An alternative
method for Audio Region analysis is to drag them directly onto the Beat Mapping track.
A pop-up menu in the Track List allows you to set the Detection Sensitivity. Changing
this setting will retrigger the analysis procedure. A higher Detection Sensitivity setting
will detect more transients, which can be useful if dealing with less distinct accents in
the music (such as rather soft drums in a loud mix). On the other hand, a higher
Detection Sensitivity setting might lead to the detection and display of transients that
have no meaning for the rhythmic structure of a Region. In general, you should begin
with a lower Detection Sensitivity setting, and only switch to a higher setting if obvious
rhythmic elements in the music aren’t recognized correctly.
Note: The detection ability is independent of the overall volume of a Region. In other
words, the results will be the same if you normalize a Region.