Re: [LAU] Aeolus organ pipes

On Thu, May 22, 2008 at 02:09:58PM +0200, Julien Claassen wrote:

> I think this is mainly to Fons, but probably someone else can help as well.
> What is required to record new organ pipes for aeolus? Would that be
> appreciated anyway. I know that it requires graphical analysis and a few other
> things afterwards, which I CAN'T do anyway. But we have a nice newer organ
> here in Soest. They just finished it about a year ago. I just thought, if I
> could fullfill the basic requirements, I might ask them.

It's quite a lot of work, and how you would approach it depends for a
large part on your experience in doing it. Creating a new stop requires
a mix of analysing recordings of single pipes, and use of 'background
knowledge' you acquire from acoustics and psychoacoustics. If you get
somewhat experienced you can in some cases skip the technical analysis,
guess most of the parameters, adjust them interactively, and compare by
ear with either recordings of single pipes, or music performed using the
stop you want to create. The latter is always the final step anyway.

The numbers of possible parameters for a single stop is quite large.
They are defined at intervals of a minor third, every C, Eb, F# and A.
For each of these notes you have

  64 harmonic levels
  64 harmonic attack speeds
  64 harmonic attack profiles
  64 random variation ranges

plus

  volume,
  unstability,
  random detune,
  systematic detune,
  attack detune,
  attack detune time,
  release detune,
  release detune time

This is a total of 5544 parameters for each stop, plus binary
flags saying if they are defined or not.

Aeolus has a built-in graphical editor for these parameters.
The ae0 files which contain them are binary, there is currenlty
no textual form of them. You could write a conversion tool...

Not all parmaters for all notes need to be defined - if a note
is missing the value will be interpolated from the values of the
two nearest notes which have that parameter defined. Each parameter
must be defined for at least one note. There is no interpolation
in the harmonics dimension as the 64 values are assumed to be
independent. But instead of this you can have a 'freehand drawing'
mode in that dimension.

-- 
FA
Laboratorio di Acustica ed Elettroacustica
Parma, Italia
Lascia la spina, cogli la rosa.
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