Fairlight-CMI

Hi Tobias & Fabian,
 
Many thanks for such thoughtful comments.

All the issues you raised can be addressed by the approach I am considering.
Vari-speed for sure. No loss of resolution from summing, sure. That's
because the Crystal Core is not a DSP, it is a bunch of gates that can be
configured to make whatever is needed for the task.

If you are interested in the technicalities, read this whitepaper:
http://www.fairlightau.com/Downloads/Public/Crystal%20Core%20Technology%20Wh
ite%20Paper%20October%202006.pdf

Here's one relevant part (the whole paper is worth a look). You will see why
this platform spaked my imagination.

4. Dynamic Resolution Optimization
The World's first combination fixed/floating point professional media
platform --
with variable precision.
There are two established signal processing paradigms that are used in
professional
digital media systems: fixed point and floating point. Whether they are
using fixed or
floating point, current systems also have a fixed precision from end to end.
For example,
they are either 32 bit fixed point OR 32 bit floating point. Each paradigm
has advantages
as discussed further below.
A unique feature in the design of the CC-1 architecture allows Fairlight to
implement both
paradigms in the Crystal Core.
Fairlight's revolutionary Dynamic Resolution Optimization (DRO) architecture
enables the
optimal precision needed for a specific task to be used within each of its
Nodes. This
uncompromising design means ultra-precise 72-bit fixed point can be used in
CC-1's EQ
Node, while optimal 36-bit floating point can be used in the Mixing node. In
areas where
extreme precision is not required, CC-1 adjusts the precision accordingly.
For example,
audio metering is more than adequately specified at 16-bit fixed point. DRO
is unique,
and is patented by Fairlight worldwide.
Dynamic Resolution Optimization (DRO) provides unsurpassed quality by
allowing the
best processing for the task at hand. This not only improves quality, but
exponentially
increases efficiency, providing greater performance at a lower cost.
Traditional systems must maintain the highest precision required from end to
end, using
either fixed point or floating point paradigms (not both). These aging and
inflexible
architectures are made to look like costly compromises, and dinosaurs with
inherent
disadvantages for some tasks.
DRO supports both sides of the resolution debate as referenced below by
delivering a
solution and without the need for any compromise.
"The double precision 48-bit processing is used when long time constants are
required.
This occurs when low frequency filters are on the job and when compressors,
expanders
and limiters are used with their relatively slow attack and release times.
If 24 bits are all
that are available when more precision is required, the results are a
problem. The
function misbehaves and the least damaging result is poor sound quality. The
worst
result is amplifier or loudspeaker damage due to a misbehaving DSP
crossover, making
double precision a must-have for superior audio."
( Greg Duckett and Terry Pennington of Rane Audio, "Superior Audio Requires
Floating
Point", published on the Rane Audio website
http://www.rane.com/note153.html)
Another example:
"The first observation is that digital filtering when we allow the user to
select high-Q, very
low-frequency filters is difficult at the best of times. Even 64-bit
floating point can produce
significant error energy if the best filter forms are not used. Even for
floating point, it is
important to use forms that have normalized state variables so that
imbalances in the
state values do not lead to further degradation of the precision of the
result. Clearly, the
performance of 32-bit floating point and 24-bit integer will be considerably
inferior to that
of 64-bit floating point, so we might conclude that it is not possible to
achieve high-quality
results for these extreme filter settings. Furthermore it is shown that
sweeping the
settings of a filter with time excites some aberrant behavior when the state
variables are
not normalized, even with 64-bit floating-point arithmetic. 48-bit integer
is proposed as a
compromise between economic realizability and ultimate precision. The
increased
headroom and guard bits allowed by the format provide enough precision to
allow some
extreme filter settings and still preserve a 24-bit result after several
stages of processing."
( Andy Moorer - pioneering digital audio engineer and currently head of
computer science
at Adobe. 48-BIT INTEGER PROCESSING BEATS 32-BIT FLOATING POINT FOR
PROFESSIONAL AUDIO APPLICATIONS, available at
http://www.jamminpower.com/PDF/48-bit%20Audio.htm)
DRO serves as yet another example of the disruptive nature of Crystal Core
technology.
DRO's dramatically improved performance, greater efficiency and lower cost
signals the
end of the legacy media processing era.



Peter