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In SONAR, decibels are used in several places:
• To scale the amplitude of the waveform (3dB Louder and 3dB Quieter
commands)
• To indicate volume levels of audio tracks in the Track view and Console view
• To indicate the effects of filters and equalizers
The reference level (0 dB) usually corresponds to the current loudness of the
sound. A positive change in decibels makes the sound louder; a negative change
makes the sound quieter.
Audio Clips
If you have read from the beginning of the chapter, you should have a good idea of
what is contained in a SONAR audio clip. An audio clip contains a long series of
numbers, or samples, representing the fluctuating amplitude of a waveform. Audio
clips are typically quite large, hundreds of kilobytes to many megabytes in size. By
comparison, a MIDI event takes only a few bytes to store.
The Track view lets you see your audio waveforms in great detail; you can zoom in
until you see the individual samples.
You should also now be aware of some things to watch out for when editing your
audio data. First, if you cut audio clips apart or splice them together, you should do
so at zero-crossings in the waveform (places where the amplitude is zero), in order
to avoid sudden changes in amplitude that may cause clicks and pops. Second, you
should beware of clipping. Clipping of the audio waveform can occur if you record a
signal at too high a record level, or if you apply audio processing or effects that
increase the waveform amplitude too much. If you accidentally cause the
waveform to clip, you should undo the command and try again with different
parameters.
Clipping can also occur in other situations, for example, if you try to play or mix
several loud audio tracks together, the aggregate signal strength may at times
exceed the clipping limit, and the output signal will be distorted. To correct the
problem, you can create a volume envelope to reduce the level in loud audio clips or
reduce the track volume in the Console or Track views.
Managing Audio Data
Because of the great size of audio data, SONAR uses an intelligent scheme for
storing audio clips on disk to conserve disk space and minimize the time it takes to
load and save data. Audio data is not stored directly in your project file, but rather
in separate files in a special directory. For more information, see “System
Configuration” on page 628.
You can export your project as RealAudio, MP3, WMA, or a Wave file. You can also
convert your project’s MIDI data to audio and export it to any of the above formats.
For more information, see “Preparing Audio for Distribution” on page 459.
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