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Appendix B - IDR™ In Depth
Dithering and Noise Shaping
Dithering and Noise Shap
perceived quality of digital a
improvement of a dif
ferent subjective quality of the noise caused by re-quantization.
Dithering alters the character of the qu
than digita
l quantization noise. The m
between
the quantization noise and th
typical
of digital quantization noise. Th
steadie
r, less displeasing analog-hi
Noise Shaping psycho-acoustical
spectrum, by taking into account th
Shaping dec
reases noise level in the 1-6
increasing
noise level in the frequency range above 15 kHz to which the ear is les
In short, d
ithering and noise sh
making it less displeasing
Here's how Dithering and Noise Shaping help maintain 3 more bits of detail: Our brains are capable of
perceiving details that are lower than the noise floor. Since quantization noise is correlated to the
signal, it effectively masks the signal
allowing our brain to distinguish signal from noise and thus perceive low level details. Noise shaping
adds even more detail by shifting noise
IDR™ Dither Options
T
ype1
T
ype 1 is a wide-band dither. Type1 adds a certain amount of noise, causing a 5dB increase in
b
ackground noise. It completely eliminates low-level distortion and signal-dependent modulation
effects. The result is a very transparent and clean low-level sound with a high resolution. It most
resembles the steady low-level hiss of an excellent quality analog system with no digital quantization
noise.
Type1 delivers no nonlinear distortion or modulation noise at low levels, and generates minimal side
effects when used with stereo signals. It is the recommended choice for high quality mastering
applications. By combining level maximization and IDR™ processing, 16-bit audio created from 20 or
24-bit masters have an apparent resolution of 19 bits. This is an improvement of more than 18dB.
Finally, unlike other dithering engines that are designed for single-stage CD mastering, IDR™ Type 1 is
optimized for use at every processing stage, allowing for subsequent signal processing.
ing are two in
dependent, com
udio after it
has been re-qu
antization noise to
ain effect of ditheri
e original signal, t
e dithering proces
ss type noise.
ly optimizes the distribution
e frequency ranges to w
kHz range
aping work by modifying the ch
to ou
r ears.
. Dithering breaks th
to a less audib
plementary techniques tha
antized. Each technique is
more closely resemble analog hiss, rather
ng is to
reduce or eliminate all correlation
hus minimizing the non-lin
s replaces the non-linear
of overall noise energy across the
hich the ear is mo
, a range to which the ear is se
aracter and frequency content of noise,
is correlation by inserting random signals,
le range, away from the desired signal.
L3-LL User Manual
t imp
rove the
respo
nsible for the
ear d
istortion effects
distor
tion sound with
st sensitive. No
ise
nsitiv
e, while
s sens
itive.
25
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