DigiDesign DigiRack, Manual

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Chapter 6: DigiRack Real-Time TDM and RTAS Plug-ins 61
POW-r Dither
(Pro Tools HD and Pro Tools LE Only)
The POW-r Dither plug-in is an advanced type
of dither that provides optimized word length
reduction. It is designed for final-stage critical
mixdown and mastering tasks where the highest
possible fidelity is desired when reducing bit
depth. For more information on dithering, see
“Dither” on page 59.
POW-r Dither Controls
Bit Resolution
Use this pop-up menu to choose either 16- or
20-bit resolutions for POW-r Dither processing.
Set this control to the maximum bit resolution
of your destination.
16-bit
Recommended for output to devices with
a maximum resolution of 16-bits, such as DAT
and CD recorders.
20-bit
Recommended for output to devices that
support a full 20-bit recording data path.
Noise Shaping
Noise shaping improves audio performance and
lessens our perception of the noise inherent in
dithering schemes by shifting audible noise
components into a less audible range.
The POW-r Dither plug-in provides three types
of noise shaping, each with its own characteris-
tics. Try each noise shaping type and choose the
one that adds the least amount of coloration to
the audio being processed.
Type 1
Has the flattest frequency spectrum in
the audible range of frequencies, modulating
and accumulating the dither noise just below
the Nyquist frequency. Recommended for less
stereophonically complex material such as solo
instrument recordings.
Type 2
Has a psychoacoustically optimized low
order noise shaping curve. Recommended for
material of greater stereophonic complexity.
Type 3
Has a psychoacoustically optimized high
order noise shaping curve. Recommended for
full-spectrum, wide-stereo field material.
POW-r Dither plug-in
The POW-r Dither plug-in does not run on
third party applications that use DAE.
The multichannel TDM version of the
POW-r Dither plug-in is not supported at
192 kHz. Use the multi-mono TDM or
RTAS version instead.
The POW-r Dither plug-in is not appropri-
ate for truncation stages that are likely to be
further processed. It is recommended that
POW-r Dither be used only as the last insert
in the signal chain (especially when using
Type 1 Noise Shaping).
Refer to the Pro Tools Reference Guide for
details on using the Dither plug-in.