Apple Logic Pro 9 - Manual (Page 567)

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 about this
plug-in, see the Logic Pro Effects manual.
Removing DC Offsets in the Sample Editor
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.
To center the waveform around the zero amplitude line
µ
Choose Functions > Remove DC Offset.
Adjusting the Project Tempo in the Sample Editor
Just like automatic tempo matching functions in the Arrange area, the Functions > “Adjust
Tempo by Selection and Locators” command adjusts the project tempo, in accordance
with the current locator positions and selected area in the Sample Editor.
Although this operation is similar to the Arrange function (see Setting the Project Tempo
to Match an Audio Region ), it applies only to the selected area of the audio file in the
Sample Editor, rather than to the overall length of the region.
Using Sample Editor Loop Functions
The Sample Editor Loop functions, available from the Edit menu, are ideal for use with
the EXS24 mkII sampler. For details about the EXS24 mkII, see the Logic Studio Instruments
manual.
You can also use these functions to generate audio files that contain the loop settings in
the file header. This allows you to make full use of these files in any application that can
read the loop information in the file header.
To use the Sample Editor Loop commands
1 Choose either of the following selection commands from the Edit menu:
• Sample Loop
→
Selection: The loop area (defined by the loop start and end points) is
used to select a portion of the overall audio file.
• Selection
→
Sample Loop: The selected area is used to set the loop start and end
points.
2 Choose Edit > Write Sample Loop to Audio File.
The new loop values will be written to the file header.
567 Chapter 17 Editing Audio in the Sample Editor