Dither - Merging Pyramix User Manual

Dither

Whenever changes are made to digital audio signals such as mixing, altering gain, eq or reverb, the result is usually
an increase in the number of bits. These extra bits have to be removed to suit the requirements of delivery and
interconnect standards. If the bit depth is reduced by simply ignoring the extra bits (truncation) or even rounding
the least significant bit up or down, the resulting error can give rise to audible distortion of low signal levels. Obvi-
ously, there is also a permanent loss of resolution. These effects are cumulative. I.e. If the signal is repeatedly pro-
cessed and bit reduced to shorter word lengths, there will be a significant and audible loss of accuracy in subtle,
low level sounds. Human hearing makes use of this low level information in imaging and unless something is
done to avoid the problem, space and clarity will be adversely affected.
In Pyramix all processing takes place in 32 bit floating point so, if signals are kept within this environment, there is
no need for bit depth reduction until the final stage before output. Truncation or rounding are undesirable but a
single 'dithering' stage can reduce bit depth whilst maintaining low level linearity. This is achieved by adding a
controlled amount of low level noise to the signal. Since there is no such thing as a free lunch, the trade off is a
slightly increased level of noise. However, the noise can be 'shaped' to reduce its perceived audibility.
See also: Dithering Options on page 223
It is important dithering is only applied once.
Project Processes : Dither 17 - 366