| Hello,
The following message was sent to me by Robert Bristow-Johnson. I thought
it would be of some interest to this list. I am reposting to the Csound
list with his permission. He asked that I be sure to credit him with this
work. I'll be working on a set of instruments based on this work soon...
Bye,
Hans Mikelson
Robert Bristow-Johnson wrote:
>i have a little addendum to that paper for other parametric EQ types
>using a biquad filter or equivialent. all formulae were derived
>from analog prototypes and had been digitized using the bilinear
>transform. earlier on comp.dsp, i posted formulae for a peaking EQ
>in which the bandedqes was not defined as the mid-dB gain and was
>given an arbitrary given gain. Bilinear Transform frequency warping
>was taken into account for both significant frequency relocation and
>for bandwidth readjustment.
>
>first, given a biquad transfer function defined as:
>
>
> H(z) = [b0 + b1*s + b2*s^2] / [a0 + a1*s + a2*a^2]
>
>this shows 6 coefficients instead of 5 so, depending on your
>architechture,
>
>-- you will likely normalize a0 to be 1 and perhaps also b0 to 1 (and
>collect
>that into an overall gain coefficient).
>
>given:
>
> frequency (wherever it's happenin', man. "center" frequency or
> "corner" frequency depending on which filter type)
>
> dBgain (used only for peaking and shelving filters)
>
> bandwidth (between midpoint gain frequencies for peaking and
>between
> -3 dB for BPF and notch)
>
> _or_ Q (EE type definition)
>
> _or_ S, a "shelf slope" parameter. when S = 1, the shelf slope
>is as
> steep as you can get it and remain monotonically
>increasing or
> decreasing gain with frequency.
>
>
>
>first compute a few intermediate variables:
>
> A = sqrt(10^(dBgain/20)) = 10^(dBgain/40)
>
> omega = 2*PI*frequency/sampleRate
>
> Q = sin(omega)/[ ln(2)*bandwidth*omega ] (if unspecified)
>
> alpha = sinh(1/(2*Q))*sin(omega)
>
> beta = sqrt((A^2 + 1)/S - (A-1)^2)
>
> then compute the coefs for whichever filter type you want:
>
>LPF: b0 = (1 - cos(omega))/2
> b1 = 1 - cos(omega)
> b2 = (1 - cos(omega))/2
> a0 = 1 + alpha
> a1 = -2*cos(omega)
> a2 = 1 - alpha
>
>
>HPF: b0 = (1 + cos(omega))/2
> b1 = -1 - cos(omega))
> b2 = (1 + cos(omega))/2
> a0 = 1 + alpha
> a1 = -2*cos(omega)
> a2 = 1 - alpha
>
>
>BPF: b0 = alpha
> b1 = 0
> b2 = -alpha
> a0 = 1 + alpha
> a1 = -2*cos(omega)
> a2 = 1 - alpha
>
>
>notch: b0 = 1
> b1 = -2*cos(omega)
> b2 = 1
> a0 = 1 + alpha
> a1 = -2*cos(omega)
> a2 = 1 - alpha
>
>
>peakingEQ: b0 = 1 + alpha*A
> b1 = -2*cos(omega)
> b2 = 1 - alpha*A
> a0 = 1 + alpha/A
> a1 = -2*cos(omega)
> a2 = 1 - alpha/A
>
>
>
>lowShelf: b0 = A*[ (A+1) - (A-1)*cos(omega) +
>beta*sin(omega) ] b1 = 2*A*[ (A-1) -
>(A+1)*cos(omega) ]
> b2 = A*[ (A+1) - (A-1)*cos(omega) -
>beta*sin(omega) ]
> a0 = (A+1) + (A-1)*cos(omega) +
>beta*sin(omega)
> a1 = -2*[ (A-1) + (A+1)*cos(omega) ]
> a2 = (A+1) + (A-1)*cos(omega) -
>beta*sin(omega)
>
>
>highShelf: b0 = (A+1) - (A-1)*cos(omega) +
>beta*sin(omega)
> b1 = 2*[ (A-1) - (A+1)*cos(omega)) ]
> b2 = (A+1) - (A-1)*cos(omega) -
>beta*sin(omega)
> a0 = A*[ (A+1) + (A-1)*cos(omega) +
>beta*sin(omega) ]
> a1 = -2*A*[ (A-1) + (A+1)*cos(omega)) ]
> a2 = A*[ (A+1) + (A-1)*cos(omega) -
>beta*sin(omega) ]
>
>
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Date: Sat, 17 Jan 1998 18:32:38 -0500
From: Jean Piche
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Subject: [ANNOUNCE] - HTML Csound Manual version 3.47 beta2
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with most of the trimmings...
ftp://ftp.musique.umontreal.ca/pub/CsManual3.47b2.tar.gz
ftp://ftp.musique.umontreal.ca/pub/CsManual3.47b2.zip
ftp://ftp.musique.umontreal.ca/pub/CsManual3.47b2.sit.bin
Ascii not too far behind...
jpff, can you put up in dream...?
--
________________________________________________________
Jean Piche
Universite de Montreal
http://mistral.ere.umontreal.ca/~pichej
http://www.musique.umontreal.ca/electro/CEC/
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From: David Schuyeteneer
To: csound mailing list
Subject: dream, weird name.
Date: Sun, 18 Jan 1998 01:42:46 +0100
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Why is it that the ftp directory has the name "DREAM" ???
Just curious...
David.
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Date: Sat, 17 Jan 1998 21:31:31 -0500 (EST)
From: Larry Troxler
To: David Schuyeteneer
Cc: csound mailing list
Subject: Re: dream, weird name.
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On Sun, 18 Jan 1998, David Schuyeteneer wrote:
>
> Why is it that the ftp directory has the name "DREAM" ???
> Just curious...
>
>
> David.
>
>
It doesn't. You are probably not fully awake and just recalling last
night's dream. For that matter, how can you be sure that this message
you are reading now, is
happening in your waking life, and that your aren't just dreaming that
you're at your computer reading this.
When you actually do wakeup up for real, you'll probably find that the
"dream" directory was, in fact, just that.
Or you may find that in fact, you don't actually own a computer, but only
dream of fanciful email exchanges.
To take it one step further, how can you be sure that your idea of this
"Csound" program is not just another fabrication of of the dream state
that you may very well be immersed in right at this moment?
I hope I've answered the question for you ...
Larry
-- Larry Troxler -- lt@westnet.com -- Patterson, NY USA --
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To: csound@maths.ex.ac.uk
Date: Sat, 17 Jan 1998 22:25:08 -0500
Subject: Re: dream, weird name.
Message-Id: <19980117.222510.3838.2.jhclouse@juno.com>
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From: Jason H Clouse
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On Sat, 17 Jan 1998 21:31:31 -0500 (EST) Larry Troxler
writes:
>On Sun, 18 Jan 1998, David Schuyeteneer wrote:
>
>>
>> Why is it that the ftp directory has the name "DREAM" ???
>> Just curious...
>>
>>
>> David.
>>
>>
>It doesn't. You are probably not fully awake and just recalling last
>night's dream. For that matter, how can you be sure that this message
>you are reading now, is
>happening in your waking life, and that your aren't just dreaming that
>you're at your computer reading this.
>
>When you actually do wakeup up for real, you'll probably find that the
>"dream" directory was, in fact, just that.
>
>Or you may find that in fact, you don't actually own a computer, but
>only
>dream of fanciful email exchanges.
>
>To take it one step further, how can you be sure that your idea of
>this
>"Csound" program is not just another fabrication of of the dream state
>that you may very well be immersed in right at this moment?
>
>I hope I've answered the question for you ...
>
>Larry
Been watching Star Trek Voyager? ;)
Jason
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Date: Sat, 17 Jan 1998 19:45:29 +0000
From: Charles Baker
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Subject: Re: dream, weird name.
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Jason H Clouse wrote (in response to Larry Troxler:
> >
> >To take it one step further, how can you be sure that your idea of
> >this
> >"Csound" program is not just another fabrication of of the dream state
> >that you may very well be immersed in right at this moment?
> >
> >I hope I've answered the question for you ...
> >
> >Larry
>
> Been watching Star Trek Voyager? ;)
>
> Jason
I'd say: reading Chuang Tzu?
I'd also say that John ffitch's support of this package has been a
dream....
many thanks,
John
(oh, you too, Jean P....)
REAL QUESTION:
are there any testers or adoptors of the SHARC card on the list yet ? (oh,
and of course that
doesn't mean R. Boulanger/the Vercoes/or Paris Smagardis, etc.: you guys
are writing/selling it! I want third party response!)
I saw an excellent review of the Kyma system in the recent Electron
Musician: but that seems to be much more expensive real-time solution than
the SHARC card/Extended Csound package.
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<19980117.222510.3838.2.jhclouse@juno.com>
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To: Charles Baker
From: Richard Boulanger
Subject: Re: dream, weird name.
Cc: csound mailing list ,
Richard Dobson ,
Sal G Sofia ,
Allan S C Lee , Hans Mikelson ,
dlr.de@media.mit.edu, horner@cs.ust.hk, jpff@maths.bath.ac.uk,
r.pinkston@mail.utexas.edu, noel@imsa.edu, mr@lmsnit.be,
abhunkin@hamlet.uncg.edu, jpgather@acsu.buffalo.edu,
iperezve@othello.ucs.indiana.edu, bfudge@hmc.edu, fabio@ts.go.dlr.de,
breder@music.mcgill.ca, karpen@u.washington.edu,
pichej@mistral.ere.umontreal.ca, madole@mills.edu, dbarlow@omnids.com,
tendrich@cix.compulink.co.uk, ingalls@mills.edu, pocino@scf-fs.usc.edu,
R.W.Dobson@bath.ac.uk, brian@lightspace.com, jmobberley@cctr.umkc.edu,
ballora@sound.music.mcgill.ca, rubo@berlin.snafu.de, Erik_Spjut@hmc.edu,
hbyrne@pavilion.co.uk, russell@best.com, Marc.Resibois@ping.be,
gogins@nyc.pipeline.com, stephen@cbr.dit.csiro.au, mup015@bangor.ac.uk,
volkov@uceam.intec.ru, mikeb@mills.edu, sdb@luigi.music.lsu.edu,
eric@iamas.ac.jp, klapper@regent.uci.agh.edu.pl, abart@berlin.netsurf.de,
j.m.clarke@hud.ac.uk, bv@media.mit.edu, johnb@gamefx.com,
Fretnoize@aol.com, rcb@media.mit.edu, anechoic@pop.sirius.com,
dlphilp@mail.bright.net, jnelson@sndart.cemi.unt.edu, paris@media.mit.edu,
tkatsia@sound.music.mcgill.ca, eduardo@music.gla.ac.uk,
fmgaete@pop.ma.ultranet.com, RichardFurse@muse.demon.co.uk,
r.a.fischman@cc.kl.ac.uk, a.lee@qub.ac.uk,
mainger@postbox.acs.ohio-state.edu,
"Vercoe, Scotty" , bv@media.mit.edu,
Max Mathews ,
Erez Webman ,
Riccardo Bianchini , Jen Scaturro ,
Gabriel Maldonado
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Dear Charles and Members of the Csound Community,
For several years I worked as a consultant to Analog Devices and assited
Barry Vercoe and ADI in defining and debugging the Extended Csound language
and the Extended Csound SDK. For this work, I was paid extremely well.
(But I also paid the price for all the stress and strain as I sufferred a
stroke in the process! Fortunatly I regained most of my faculties.)
As of January 1, 1998, I am no longer under contract with Analog Devices
and am definately NOT SELLING their stuff.
Also, it is improtant to note that over the last three years, I managed to
get one of my most brilliant and gifted students - Paris Smaragdis - some
consulting work with ADI on this project. For that 8 months of work ADI
also paid him pretty well. But he no longer works for Analog Devices and
is definately NOT SELLING their stuff. In fact, Paris Smaragdis has not
worked for ADI for over two years.
I have nothing further to say about the ADI system, but if you would like
to get an objective/ousider's perspective on the ADI SDK you should contact
Kim Cascone
<> kim.cascone <>
<>sound.designer -- headspace<>
<>anechoic@sirius.com<>
<>http://www.sirius.com/~anechoic<>
======
>Jason H Clouse wrote (in response to Larry Troxler:
>
>> >
>> >To take it one step further, how can you be sure that your idea of
>> >this
>> >"Csound" program is not just another fabrication of of the dream state
>> >that you may very well be immersed in right at this moment?
>> >
>> >I hope I've answered the question for you ...
>> >
>> >Larry
>>
>> Been watching Star Trek Voyager? ;)
>>
>> Jason
>
> I'd say: reading Chuang Tzu?
>
>I'd also say that John ffitch's support of this package has been a
>dream....
>many thanks,
>John
>(oh, you too, Jean P....)
>
>REAL QUESTION:
>are there any testers or adoptors of the SHARC card on the list yet ? (oh,
>and of course that
>doesn't mean R. Boulanger/the Vercoes/or Paris Smagardis, etc.: you guys
>are writing/selling it! I want third party response!)
>
>I saw an excellent review of the Kyma system in the recent Electron
>Musician: but that seems to be much more expensive real-time solution than
>the SHARC card/Extended Csound package.
==================
Dr. Richard Boulanger
Professor
Music Synthesis Department
Berklee College of Music
1140 Boylston Street
Boston, MA 02215-3693
Berklee Phone: (617) 747-2485 Berklee Fax: (617) 536-2257
======================================================
email: rcb@media.mit.edu * rcb@tiac.net * rboulanger@berklee.edu
webpage: http://www.tiac.net/users/rcb
================================
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From: David Schuyeteneer
To: csound mailing list
Subject: DREAM, serious now
Date: Sun, 18 Jan 1998 13:15:11 +0100
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Why is it that there is a "DREAM" subdir on the ftp server ???????
I mean not its contents but its name of course..."dream"...why not
"bugsbunny" or "flyhigh" ?
(only serious replies please ;-))
David.
|