[gmpi] Re: Where are we?: 7.1.2/Untangling issues

on 6/18/03 5:02 AM, Steve Harris at S.W.Harris@xxxxxxxxxxxxxxx wrote:

> On Tue, Jun 17, 2003 at 11:44:08 -0400, B.J. Buchalter wrote:
>> Probably not. It seems like it would make more sense to have multiple
>> subgraphs, each running with the proper type (e.g. The modular synth hosts
>> Float64 modules, but is itself a Float32 plug -- if the Float64 proves to be
>> required [if there is feedback, our tests would indicate that it is
>> required].
> 
> Thats interesting, I know several modular systems that use 32bit float (or
> 24bit fixed) for module i/o, even with blockless processing, when did you
> find you needed it?

We have not tested the modular synth type of graph, so I am not really
speaking to that specific operation but I have tested things like IIR filter
implementations where I can measure significant differences in noise floor
structure and in listening tests that has a real impact on the sound (the 64
bit implementation is smoother and other weird subjective kind of words). So
if you were implementing very fine-grained modules I can see how there would
be an important difference between the two types of transport. Similarly, I
know that there is an important difference when recursive structures are
followed by large gain elements (eg. IIRs followed by compressors). With
Float32 the problem is much less than with Fixed representations since the
precision is preserved. In any case we currently use a Float64 domain inside
our plugs with Float32 I/O since that is what the current P/I systems
support. For fine-grained recursive structures we have seen measurable
differences. Which is not to say that you can't implement these systems with
Float32 or Fixed24 -- obviously you can. But that does not mean that there
is not anything to be gained from Float64 transport. Of course there are
significant drawbacks with current architectures as well. But I would not
implement the internal structure of our plugs with Float32 today unless I
was making a lower quality plug, so I can see why there are folks who have
the need for Float64 interconnect.

Best regards,


B.J. Buchalter

Metric Halo
M/S 601 - Building 8
Castle Point Campus
Castle Point, NY 12511-0601 USA
tel +1 845 831-8600
fax +1 603 250-2451

If you haven't heard ChannelStrip yet, you don't know what you're missing!

Check out SpectraFoo, ChannelStrip and Mobile I/O at http://www.mhlabs.com/

Download a 12 day demo from <http://www.mhlabs.com/demo/>




----------------------------------------------------------------------
Generalized Music Plugin Interface (GMPI) public discussion list
Participation in this list is contingent upon your abiding by the
following rules:  Please stay on topic.  You are responsible for your own
words.  Please respect your fellow subscribers.  Please do not
redistribute anyone else's words without their permission.

Archive: http://www.freelists.org/archives/gmpi
Email gmpi-request@xxxxxxxxxxxxx w/ subject "unsubscribe" to unsubscribe

Other related posts: