Reference Guide

1254
Dialog Reference
Audio Options dialog—Advanced
improve SONAR’s audio performance.
• I/O Buffer Size. This value determines the buffer characteristics for transfers to and from the
disk. Changing this value does not affect audio latency, but will affect the disk throughput for audio
tracks. The default setting is 128. A higher value causes more audio to be buffered from the disk
ahead of the playback cursor. If you are hearing consistent dropouts/clicks in your audio and if
your project contains high bit depth (32/64 bit) or high sample rate audio (88.2K or higher), it may
be indicative of a too small I/O buffer size. If so try a higher I/O buffer size like 256 or 512. If audio
problems persist, reset to 128 and try a different remedy.
Also, if you are playing a large file, and using maximum latency, a too-small I/O buffer size may
cause dropouts or crashes. Try increasing the buffer size by blocks of 128.
Playback and Recording
• Driver Mode drop-down menu. Select from WDM/KS, ASIO or MME. Consult your hardware
documentation to determine which driver your hardware uses. WDM/KS drivers are the latest
available and typically have very low latency. MME is an older driver type and has higher
latencies. ASIO drivers also offer lower latency. Your hardware may have all three driver options.
If so, you should try WDM first.
• 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 Tools > 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) on the Audio Data tab of the Global Options dialog (opens with Options > Global
command), 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).
Note: Changes to these settings only take effect when you restart SONAR.