Reference Guide

1560
Preferences dialog
• Dithering. Whenever an audio signal is converted from a higher-bit resolution to a lower
resolution, it is necessary to apply dither to avoid introducing undesirable quantization noise or
harmonic distortion into the signal. The purpose of dither is to reduce the resulting distortion by
adding low-level random noise or “dither” to the audio signal. Different mathematical calculations
are used to generate dither, each method has advantages and disadvantages depending on the
particular operation. SONAR features the Pow-r dithering process, short for Psycho-acoustically
Optimized Wordlength Reduction, which can produce lower-bit files that sound indistinguishable
from higher-bit source files. When this option is turned on, SONAR uses dithering when you
export a higher-bit file at a lower resolution, or lower the bit depth of a project’s audio files by
using the Utilities > Change Audio Format command, or when you “render” audio (bounce,
freeze, or apply effects).
This option is turned on whenever the Dithering field has a value other than None. You can
choose bit depths for recording, importing, and rendering (bouncing, freezing, and applying
effects) in Edit > Preferences > File - Audio Data, and for exporting in the Export Audio dialog
(File > Export > Audio command). SONAR offers five kinds of dithering:
• Rectangular. Essentially white noise, no noise shaping. Advantages: least CPU-intensive,
lowest signal-to-noise ratio, preferable to shaped dither when successive dithering can occur
(e.g. bouncing, freezing). Disadvantages: suffers from intermodulation distortion, higher
perceived loudness than Pow-r dither.
• Triangular. Higher level than rectangular, no noise shaping. Advantages: low CPU-intensive
dither, superior to Rectangular as it does not suffer from modulation noise effects. Preferable to
shaped (Pow-r) dither when successive dithering can occur (e.g. bouncing, freezing).
Disadvantages: higher perceived loudness than Pow-r dither.
• Pow-r 1. Noise-shaped dither. Advantages: less CPU-intensive than Pow-r types 2 and 3,
lower perceived loudness than Rectangular or Triangular. Disadvantages: less noise shaping
than Pow-r types 2 and 3, not recommended for operations where dither will be applied
successively (e.g. bounce and freeze).
• Pow-r 2. Noise-shaped dither. Advantages: lowest perceived loudness, highest quality
settings, recommended for audio export. Disadvantages: highest CPU-intensive settings, not
recommended for operations where dither will be applied successively (e.g. bounce and
freeze).
• Pow-r 3. Same as Pow-r 2 except most CPU-intensive and transparent of all choices.
• Share Drivers With Other Programs. This option allows other software to access device
drivers. When this option is checked, other software can access device drivers when SONAR is
not the focus of Windows.
• Use Multiprocessing Engine. This option is grayed out unless you have a multiprocessor
computer. If you have a multiprocessor computer, check this option if you want SONAR to use
both processors at all times. If you do not check this option, SONAR still uses the second
processor for some tasks.
• Use MMCSS (Windows Vista). This option is grayed out unless you use Windows Vista. This
option gives real-time applications such as SONAR higher priority for resource scheduling (thread
scheduling) under Windows Vista (leave it checked).