Apple Soundtrack Pro 2 - Manual (Page 237)

Chapter 6 Editing Audio Files 237
DC Offset
DC offset is a shift in the audio, causing the positive and negative parts of the signal
not to average to zero. DC offset can limit the dynamic range of an audio file.
Phase Issues
Phase issues can result from a distorted or inaccurate stereo image, caused by poor
microphone placement or other issues. When converting a stereo file to mono, the
presence of phase issues can cause the left and right channels to cancel each other out
partially or completely.
Clipped Signal
A clipped or overloaded signal can result from several causes, including poor gain
staging in a preamp during recording, bad electrical cables, or surface damage to an
analog recording. If analysis identifies a clipped signal, Soundtrack Pro gives you the
option to soften the abrasive nature of the truncation.
Silence
Silence detects the parts of the audio file at which the audio signal falls to zero (0). You
can set the threshold below which Soundtrack Pro considers the signal to be silence.
To select the types of analysis to perform:
1 In the Analysis Type list, select the checkboxes next to the types of analysis you want to
perform on the audio file.
2 To analyze the file, click Analyze.
When analyzing an audio file in the File Editor, some analysis types might produce
better results if you select a part of the audio file instead of the entire audio file.
The Power Line Hum, DC Offset, and Phase analysis types determine whether the audio
file or selection exhibits these problems. Because hum, DC offset, and phase issues tend
to last for long times, up to the entire length of the file, better results might be achieved
when analyzing the entire audio file or the part of the file you think has the problem.
On the other hand, the Clicks and Pops, Clipped Signal, and Silence analysis types tend
to be momentary and isolated rather than constant. If part of an audio file or selection
contains a large number of clicks and pops, for example, the analyzed waveform might
display the entire region as being problematic, rather than each individual click or pop.
However, when you fix these problems using the Fix button, Soundtrack Pro correctly
fixes each individual click or pop.
The Clicks and Pops Threshold slider uses an algorithm to detect transients that are
clicks or pops. Moving the slider to the right results in fewer clicks or pops being
detected. The Silence Threshold slider ranges from 0% to 10% of the full-scale level of
the audio file, which corresponds to a range of –infinity dB to –20 dB.