Manual

500 Chapter 21 Editing Audio in the Sample Editor
You can set the desired maximum level in the Function Settings window, which you
can open by choosing Functions > Settings (or by clicking the Settings button in the
Normalize dialog).
Set the desired maximum level (as a percentage or in decibels) in one of the Peak at
fields.
∏ Tip: You should not choose 100% (0 dB) in these fields, as this may result in clipping
should you wish to increase the gain of the overall signal afterwards, say with an EQ. As
a good rule of thumb, you should leave yourself at least 3 to 6 dB of headroom, to
allow for further audio processing tasks, such as mixing and effects processing.
These settings are automatically stored in the Preferences when Logic Pro is closed, and
apply to all projects.
Reversing the Phase of a Selection Area
You will find the Invert command extremely useful for correcting phase cancellation
errors, or when several out of tune signals (or several signals processed through chorus
effects), are to be mixed down to mono.
To completely reverse the phase of all currently-selected audio material:
m Choose Functions > Invert.
All negative amplitude values become positive, and vice versa.
Note: This doesn’t audibly change the file, if heard in isolation. The process depends
heavily on the audio material.
∏ Tip: You can also use the Invert function to decode mono/stereo recordings, but it’s far
easier to use the Direction Mixer plug-in for this task. For more information on this
plug-in, see the Logic Studio Instruments and Effects manual.
Removing DC Offsets
Some audio interface hardware can layer direct current (DC) over the audio signal. This
results in a vertical shift in the waveform position, which can be clearly seen in the
Sample Editor.
During playback, this can cause crackling sounds at the start and end of the audio
region.