From fc3d3c0a4f110a23335398c327ac0a4fc949d5cb Mon Sep 17 00:00:00 2001
From: Guenter  Geiger <ggeiger@users.sourceforge.net>
Date: Mon, 17 Jun 2002 10:13:57 +0000
Subject: This commit was generated by cvs2svn to compensate for changes in
 r12, which included commits to RCS files with non-trunk default branches.

svn path=/trunk/externals/ggee/; revision=13
---
 filters/Makefile     |  50 ++++++++++++
 filters/bandpass.c   |  86 ++++++++++++++++++++
 filters/bandpass.pd  |  38 +++++++++
 filters/equalizer.c  |  89 ++++++++++++++++++++
 filters/equalizer.pd |  39 +++++++++
 filters/filters.h    |  74 +++++++++++++++++
 filters/filtgain.pd  |  74 +++++++++++++++++
 filters/highpass.c   |  87 ++++++++++++++++++++
 filters/highpass.pd  |  35 ++++++++
 filters/highshelf.c  |  90 ++++++++++++++++++++
 filters/highshelf.pd |  39 +++++++++
 filters/hlshelf.c    | 226 +++++++++++++++++++++++++++++++++++++++++++++++++++
 filters/hlshelf.pd   |  34 ++++++++
 filters/lowpass.c    |  89 ++++++++++++++++++++
 filters/lowpass.pd   |  35 ++++++++
 filters/lowshelf.c   |  91 +++++++++++++++++++++
 filters/lowshelf.pd  |  39 +++++++++
 filters/moog~.c      | 182 +++++++++++++++++++++++++++++++++++++++++
 filters/moog~.pd     |  39 +++++++++
 filters/notch.c      |  89 ++++++++++++++++++++
 filters/notch.pd     |  35 ++++++++
 21 files changed, 1560 insertions(+)
 create mode 100755 filters/Makefile
 create mode 100755 filters/bandpass.c
 create mode 100755 filters/bandpass.pd
 create mode 100755 filters/equalizer.c
 create mode 100755 filters/equalizer.pd
 create mode 100755 filters/filters.h
 create mode 100755 filters/filtgain.pd
 create mode 100755 filters/highpass.c
 create mode 100755 filters/highpass.pd
 create mode 100755 filters/highshelf.c
 create mode 100755 filters/highshelf.pd
 create mode 100755 filters/hlshelf.c
 create mode 100755 filters/hlshelf.pd
 create mode 100755 filters/lowpass.c
 create mode 100755 filters/lowpass.pd
 create mode 100755 filters/lowshelf.c
 create mode 100755 filters/lowshelf.pd
 create mode 100755 filters/moog~.c
 create mode 100755 filters/moog~.pd
 create mode 100755 filters/notch.c
 create mode 100755 filters/notch.pd

(limited to 'filters')

diff --git a/filters/Makefile b/filters/Makefile
new file mode 100755
index 0000000..f002498
--- /dev/null
+++ b/filters/Makefile
@@ -0,0 +1,50 @@
+current: nt
+
+
+# TARGETS += stk
+
+VERSION = \"0.24\"
+
+.SUFFIXES: .dll .obj
+# ----------------------- NT ----------------------------
+
+NTOBJECTS = *.obj
+NTDLLS = *.dll
+
+PDNTCFLAGS = /W3 /WX /DNT /DPD /nologo
+
+PDNTINCLUDE = /I. /I..\..\pd\src 
+ProgramFiles = C:\Program Files
+PDNTLDIR = "$(ProgramFiles)\Microsoft Visual Studio\Vc98\lib"
+#PDNTLDIR = "C:\Programme\Msdev\Vc98\lib"
+
+PDNTLIB = $(PDNTLDIR)\libc.lib \
+	$(PDNTLDIR)\oldnames.lib \
+	$(PDNTLDIR)\wsock32.lib \
+	$(PDNTLDIR)\kernel32.lib \
+	$(PDNTLDIR)\uuid.lib \
+	..\..\pd\bin\pd.lib 
+
+nt: $(NTOBJECTS) 
+	-link /dll  $(PDNTLIB) bandpass.obj /export:bandpass_setup
+	-link /dll  $(PDNTLIB) highpass.obj /export:highpass_setup
+	-link /dll  $(PDNTLIB) highshelf.obj /export:highshelf_setup
+	-link /dll  $(PDNTLIB) hlshelf.obj /export:hlshelf_setup
+	-link /dll  $(PDNTLIB) lowpass.obj /export:lowpass_setup
+	-link /dll  $(PDNTLIB) notch.obj /export:notch_setup
+	-link /dll  $(PDNTLIB) equalizer.obj /export:equalizer_setup
+
+
+clean:
+	del *.obj 
+	del *.dll
+
+
+.c.obj:
+	-cl $(PDNTCFLAGS) $(PDNTINCLUDE) /c $*.c
+
+.obj.dll:
+
+
+	
+
diff --git a/filters/bandpass.c b/filters/bandpass.c
new file mode 100755
index 0000000..c4c2e13
--- /dev/null
+++ b/filters/bandpass.c
@@ -0,0 +1,86 @@
+
+/* (C) Guenter Geiger <geiger@epy.co.at> */
+
+
+/*
+
+ These filter coefficients computations are taken from
+ http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt  
+
+ written by Robert Bristow-Johnson
+
+*/
+
+#include <m_pd.h>
+#ifdef NT
+#pragma warning( disable : 4244 )
+#pragma warning( disable : 4305 )
+#endif
+#include <math.h>
+#include "filters.h"
+
+/* ------------------- bandpass ----------------------------*/
+
+static t_class *bandpass_class;
+
+void bandpass_bang(t_rbjfilter *x)
+{
+     t_atom at[5];
+     t_float omega = e_omega(x->x_freq,x->x_rate);
+     t_float alpha = e_alpha(x->x_bw* 0.01,omega);
+     t_float b1 = 0.;
+     t_float b0 = alpha;
+     t_float b2 = -alpha;
+     t_float a0 = 1 + alpha;
+     t_float a1 = -2.*cos(omega);
+     t_float a2 = 1 - alpha;
+
+/*     post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw); */
+     
+     if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
+       post("bandpass: filter unstable -> resetting");
+       a0=1.;a1=0.;a2=0.;
+       b0=1.;b1=0.;b2=0.;
+     }
+
+     SETFLOAT(at,-a1/a0);
+     SETFLOAT(at+1,-a2/a0);
+     SETFLOAT(at+2,b0/a0);
+     SETFLOAT(at+3,b1/a0);
+     SETFLOAT(at+4,b2/a0);
+     
+     outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
+}
+
+
+void bandpass_float(t_rbjfilter *x,t_floatarg f)
+{
+     x->x_freq = f;
+     bandpass_bang(x);
+}
+
+
+static void *bandpass_new(t_floatarg f,t_floatarg bw)
+{
+    t_rbjfilter *x = (t_rbjfilter *)pd_new(bandpass_class);
+
+    x->x_rate = 44100.0;
+    outlet_new(&x->x_obj,&s_float);
+/*    floatinlet_new(&x->x_obj, &x->x_gain);    */
+    floatinlet_new(&x->x_obj, &x->x_bw);
+    if (f > 0.) x->x_freq = f;
+    if (bw > 0.) x->x_bw = bw;
+    return (x);
+}
+
+
+void bandpass_setup(void)
+{
+    bandpass_class = class_new(gensym("bandpass"), (t_newmethod)bandpass_new, 0,
+				sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,0);
+    class_addbang(bandpass_class,bandpass_bang);
+    class_addfloat(bandpass_class,bandpass_float);
+}
+
+
+
diff --git a/filters/bandpass.pd b/filters/bandpass.pd
new file mode 100755
index 0000000..73cace4
--- /dev/null
+++ b/filters/bandpass.pd
@@ -0,0 +1,38 @@
+#N canvas 295 68 622 469 10;
+#X obj 77 199 print;
+#X floatatom 77 114 0 0 0;
+#X floatatom 139 114 0 0 0;
+#X msg 360 109 \; paint 0;
+#X obj 164 196 filtgain;
+#X msg 91 138 bang;
+#X text 139 93 bandwidth (0 - 100);
+#X text 6 334 See also:;
+#X obj 72 335 bandpass;
+#X obj 139 336 notch;
+#X obj 195 337 lowpass;
+#X obj 247 336 highpass;
+#X obj 247 358 equalizer;
+#X obj 72 357 highshelf;
+#X obj 139 357 lowshelf;
+#X obj 195 357 hlshelf;
+#X text 75 226 These filters are all controlled by a bandwidth which
+is expressed in octaves. A bandwidth of 100 is equivalent to one octave.
+;
+#X text 358 25 click first;
+#X text 186 159 click on filtgain to view frequency plot;
+#X text 76 12 Bandpass coefficients for biquad~;
+#X text 70 26 ===================================;
+#X text 6 393 (C) Guenter Geiger 2000;
+#X text 75 92 frequency;
+#X text 75 268 Attention \, only the left inlet triggers new coefficients
+for biquad~;
+#X obj 77 160 bandpass 4000 33;
+#X obj 33 114 r doit;
+#X msg 360 45 \; pd dsp 1 \; paint 1 \; doit bang \;;
+#X connect 1 0 24 0;
+#X connect 2 0 24 1;
+#X connect 2 0 5 0;
+#X connect 5 0 24 0;
+#X connect 24 0 0 0;
+#X connect 24 0 4 0;
+#X connect 25 0 5 0;
diff --git a/filters/equalizer.c b/filters/equalizer.c
new file mode 100755
index 0000000..80d8410
--- /dev/null
+++ b/filters/equalizer.c
@@ -0,0 +1,89 @@
+/* (C) Guenter Geiger <geiger@epy.co.at> */
+
+
+/*
+
+ These filter coefficients computations are taken from
+ http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt  
+
+ written by Robert Bristow-Johnson
+
+*/
+
+#include <m_pd.h>
+#ifdef NT
+#pragma warning( disable : 4244 )
+#pragma warning( disable : 4305 )
+#endif
+#include <math.h>
+#include "filters.h"
+
+
+
+/* ------------------- equ ----------------------------*/
+static t_class *equ_class;
+
+void equ_bang(t_rbjfilter *x)
+{
+     t_atom at[5];
+     t_float omega = e_omega(x->x_freq,x->x_rate);
+     t_float alpha = e_alpha(x->x_bw*0.01,omega);
+     t_float b0 = 1 + alpha*e_A(x->x_gain);
+     t_float b1 = -2.*cos(omega);
+     t_float b2 = 1;
+     t_float a0 = 1 + alpha;
+     t_float a1 = -2.*cos(omega);
+     t_float a2 = 1 - alpha;
+
+/*      post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw);*/
+     
+     if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
+       post("equ: filter unstable -> resetting");
+       a0=1.;a1=0.;a2=0.;
+       b0=1.;b1=0.;b2=0.;
+     }
+
+     SETFLOAT(at,-a1/a0);
+     SETFLOAT(at+1,-a2/a0);
+     SETFLOAT(at+2,b0/a0);
+     SETFLOAT(at+3,b1/a0);
+     SETFLOAT(at+4,b2/a0);
+     
+     outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
+}
+
+
+void equ_float(t_rbjfilter *x,t_floatarg f)
+{
+     x->x_freq = f;
+     equ_bang(x);
+}
+
+
+static void *equ_new(t_floatarg f,t_floatarg g,t_floatarg bw)
+{
+    t_rbjfilter *x = (t_rbjfilter *)pd_new(equ_class);
+
+    x->x_rate = 44100.0;
+    outlet_new(&x->x_obj,&s_float);
+    floatinlet_new(&x->x_obj, &x->x_gain);    
+    floatinlet_new(&x->x_obj, &x->x_bw);
+    if (f > 0.) x->x_freq = f;
+    if (bw > 0.) x->x_bw = bw;
+    if (g != 0.) x->x_gain = g;
+    return (x);
+}
+
+
+void equalizer_setup(void)
+{
+    equ_class = class_new(gensym("equalizer"), (t_newmethod)equ_new, 0,
+				sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,A_DEFFLOAT,0);
+    class_addbang(equ_class,equ_bang);
+    class_addfloat(equ_class,equ_float);
+}
+
+
+
+
+
diff --git a/filters/equalizer.pd b/filters/equalizer.pd
new file mode 100755
index 0000000..05f7c56
--- /dev/null
+++ b/filters/equalizer.pd
@@ -0,0 +1,39 @@
+#N canvas 561 126 620 459 10;
+#X obj 77 182 print;
+#X floatatom 77 114;
+#X floatatom 186 112;
+#X msg 360 117 \; paint 0;
+#X obj 159 175 filtgain;
+#X msg 91 138 bang;
+#X text 186 91 bandwidth (0 - 100);
+#X text 6 334 See also:;
+#X obj 72 335 bandpass;
+#X obj 139 336 notch;
+#X obj 195 337 lowpass;
+#X obj 247 336 highpass;
+#X obj 247 358 equalizer;
+#X obj 72 357 highshelf;
+#X obj 139 357 lowshelf;
+#X obj 195 357 hlshelf;
+#X text 75 226 These filters are all controlled by a bandwidth which is expressed in octaves. A bandwidth of 100 is equivalent to one octave.;
+#X text 358 25 click first;
+#X text 200 158 click on filtgain to view frequency plot;
+#X text 6 393 (C) Guenter Geiger 2000;
+#X text 75 92 frequency;
+#X text 75 268 Attention \, only the left inlet triggers new coefficients for biquad~;
+#X floatatom 129 113;
+#X text 138 92 gain;
+#X text 71 26 ==============================================;
+#X text 76 12 Parametric Equalizer coefficients for biquad~;
+#X obj 77 160 equalizer 5000 70 8;
+#X obj 31 114 r doit;
+#X msg 360 45 \; pd dsp 1 \; paint 1 \; doit bang \;;
+#X connect 1 0 26 0;
+#X connect 2 0 5 0;
+#X connect 2 0 26 2;
+#X connect 5 0 26 0;
+#X connect 22 0 5 0;
+#X connect 22 0 26 1;
+#X connect 26 0 0 0;
+#X connect 26 0 4 0;
+#X connect 27 0 26 0;
diff --git a/filters/filters.h b/filters/filters.h
new file mode 100755
index 0000000..6ff7962
--- /dev/null
+++ b/filters/filters.h
@@ -0,0 +1,74 @@
+/*
+
+ These filter coefficients computations are taken from
+ http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt  
+
+ written by Robert Bristow-Johnson
+
+*/
+
+
+#ifndef __GGEE_FILTERS_H__
+#define __GGEE_FILTERS_H__
+
+
+
+#ifndef M_PI
+#define M_PI 3.141593f
+#endif
+
+
+#include <math.h>
+#define LN2 0.69314718
+#define e_A(g) (pow(10,(g/40.)))
+#define e_omega(f,r) (2.0*M_PI*f/r)
+#define e_alpha(bw,omega) (sin(omega)*sinh(LN2/2. * bw * omega/sin(omega)))
+#define e_beta(a,S) (sqrt((a*a + 1)/(S) - (a-1)*(a-1)))
+
+
+
+
+typedef struct _rbjfilter
+{
+     t_object x_obj;
+     t_float  x_rate;
+     t_float  x_freq;
+     t_float  x_gain;
+     t_float  x_bw;
+} t_rbjfilter;
+
+
+static int check_stability(t_float fb1,
+			    t_float fb2, 
+			    t_float ff1,
+			    t_float ff2,
+			    t_float ff3)
+{
+    float discriminant = fb1 * fb1 + 4 * fb2;
+
+    if (discriminant < 0) /* imaginary roots -- resonant filter */
+    {
+    	    /* they're conjugates so we just check that the product
+    	    is less than one */
+    	if (fb2 >= -1.0f) goto stable;
+    }
+    else    /* real roots */
+    {
+    	    /* check that the parabola 1 - fb1 x - fb2 x^2 has a
+    	    	vertex between -1 and 1, and that it's nonnegative
+    	    	at both ends, which implies both roots are in [1-,1]. */
+    	if (fb1 <= 2.0f && fb1 >= -2.0f &&
+    	    1.0f - fb1 -fb2 >= 0 && 1.0f + fb1 - fb2 >= 0)
+    	    	goto stable;
+    }
+    return 0;
+stable:
+    return 1;
+}
+
+
+
+
+
+
+#endif
diff --git a/filters/filtgain.pd b/filters/filtgain.pd
new file mode 100755
index 0000000..b276a52
--- /dev/null
+++ b/filters/filtgain.pd
@@ -0,0 +1,74 @@
+#N canvas 178 144 702 459 10;
+#X obj 38 342 biquad~;
+#X obj 38 316 osc~ 220;
+#X obj 118 340 env~;
+#X floatatom 38 297;
+#X obj 38 419 dac~;
+#X obj 193 428 tabwrite array1;
+#X obj 325 400 int;
+#X obj 350 401 + 1;
+#X msg 296 399 0;
+#X obj 193 410 float;
+#X obj 218 372 t b f;
+#X obj 38 398 *~;
+#X obj 61 399 dbtorms;
+#X floatatom 368 359;
+#X obj 296 418 sel 500;
+#X obj 38 277 * 40;
+#X obj 325 380 metro 10;
+#X obj 325 359 r paint;
+#X obj 61 381 r volume;
+#X obj 38 7 inlet;
+#X floatatom 194 368;
+#X floatatom 279 360;
+#X obj 118 360 - 100;
+#X obj 118 382 * 0.01;
+#X graph graph2 0 -1 500 1 148 253 648 113;
+#X array array1 500 float;
+#X pop;
+#X msg 273 272 5000;
+#X msg 273 82 5000;
+#X msg 398 82 10000;
+#X msg 398 272 10000;
+#X msg 173 83 1000;
+#X msg 173 271 1000;
+#X text 105 6 subpatch used in filter externals see;
+#X obj 347 12 bandpass;
+#X obj 414 13 notch;
+#X obj 470 14 lowpass;
+#X obj 522 13 highpass;
+#X obj 522 35 equalizer;
+#X obj 347 34 highshelf;
+#X obj 414 34 lowshelf;
+#X obj 470 34 hlshelf;
+#X connect 0 0 2 0;
+#X connect 0 0 11 0;
+#X connect 1 0 0 0;
+#X connect 2 0 22 0;
+#X connect 3 0 1 0;
+#X connect 6 0 7 0;
+#X connect 6 0 10 0;
+#X connect 6 0 14 0;
+#X connect 6 0 15 0;
+#X connect 7 0 6 1;
+#X connect 8 0 6 0;
+#X connect 9 0 5 0;
+#X connect 10 0 9 0;
+#X connect 10 1 5 1;
+#X connect 11 0 4 0;
+#X connect 11 0 4 1;
+#X connect 12 0 11 1;
+#X connect 13 0 16 1;
+#X connect 14 0 8 0;
+#X connect 15 0 3 0;
+#X connect 16 0 6 0;
+#X connect 17 0 16 0;
+#X connect 18 0 12 0;
+#X connect 19 0 0 0;
+#X connect 20 0 5 0;
+#X connect 21 0 5 1;
+#X connect 22 0 23 0;
+#X connect 23 0 9 1;
+#X connect 26 0 25 0;
+#X connect 27 0 28 0;
+#X connect 29 0 30 0;
diff --git a/filters/highpass.c b/filters/highpass.c
new file mode 100755
index 0000000..e7e0443
--- /dev/null
+++ b/filters/highpass.c
@@ -0,0 +1,87 @@
+/* (C) Guenter Geiger <geiger@epy.co.at> */
+
+
+/*
+
+ These filter coefficients computations are taken from
+ http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt  
+
+ written by Robert Bristow-Johnson
+
+*/
+
+#include <m_pd.h>
+#ifdef NT
+#pragma warning( disable : 4244 )
+#pragma warning( disable : 4305 )
+#endif
+#include <math.h>
+#include "filters.h"
+
+
+/* ------------------- highpass ----------------------------*/
+
+static t_class *highpass_class;
+
+void highpass_bang(t_rbjfilter *x)
+{
+     t_atom at[5];
+     t_float omega = e_omega(x->x_freq,x->x_rate);
+     t_float alpha = e_alpha(x->x_bw* 0.01,omega);
+     t_float b1 = -(1 + cos(omega));
+     t_float b0 = -b1/2.;
+     t_float b2 = b0;
+     t_float a0 = 1 + alpha;
+     t_float a1 = -2.*cos(omega);
+     t_float a2 = 1 - alpha;
+
+/*     post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw); */
+     
+     if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
+       post("highpass: filter unstable -> resetting");
+       a0=1.;a1=0.;a2=0.;
+       b0=1.;b1=0.;b2=0.;
+     }
+
+     SETFLOAT(at,-a1/a0);
+     SETFLOAT(at+1,-a2/a0);
+     SETFLOAT(at+2,b0/a0);
+     SETFLOAT(at+3,b1/a0);
+     SETFLOAT(at+4,b2/a0);
+     
+     outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
+}
+
+
+void highpass_float(t_rbjfilter *x,t_floatarg f)
+{
+     x->x_freq = f;
+     highpass_bang(x);
+}
+
+
+static void *highpass_new(t_floatarg f,t_floatarg bw)
+{
+    t_rbjfilter *x = (t_rbjfilter *)pd_new(highpass_class);
+
+    x->x_rate = 44100.0;
+    outlet_new(&x->x_obj,&s_float);
+/*    floatinlet_new(&x->x_obj, &x->x_gain);    */
+    floatinlet_new(&x->x_obj, &x->x_bw);
+    if (f > 0.) x->x_freq = f;
+    if (bw > 0.) x->x_bw = bw;
+    return (x);
+}
+
+
+void highpass_setup(void)
+{
+    highpass_class = class_new(gensym("highpass"), (t_newmethod)highpass_new, 0,
+				sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,0);
+    class_addbang(highpass_class,highpass_bang);
+    class_addfloat(highpass_class,highpass_float);
+}
+
+
+
+
diff --git a/filters/highpass.pd b/filters/highpass.pd
new file mode 100755
index 0000000..e953888
--- /dev/null
+++ b/filters/highpass.pd
@@ -0,0 +1,35 @@
+#N canvas 365 183 620 463 10;
+#X obj 77 182 print;
+#X floatatom 77 114;
+#X floatatom 168 115;
+#X msg 360 109 \; paint 0;
+#X obj 159 175 filtgain;
+#X msg 91 138 bang;
+#X text 168 94 bandwidth (0 - 100);
+#X text 6 334 See also:;
+#X obj 72 335 bandpass;
+#X obj 139 336 notch;
+#X obj 195 337 lowpass;
+#X obj 247 336 highpass;
+#X obj 247 358 equalizer;
+#X obj 72 357 highshelf;
+#X obj 139 357 lowshelf;
+#X obj 195 357 hlshelf;
+#X text 75 226 These filters are all controlled by a bandwidth which is expressed in octaves. A bandwidth of 100 is equivalent to one octave.;
+#X text 358 25 click first;
+#X text 182 148 click on filtgain to view frequency plot;
+#X text 70 26 ===================================;
+#X text 6 393 (C) Guenter Geiger 2000;
+#X text 75 92 frequency;
+#X text 75 268 Attention \, only the left inlet triggers new coefficients for biquad~;
+#X text 76 12 Highpass coefficients for biquad~;
+#X obj 77 160 highpass 4000 33;
+#X obj 34 113 r doit;
+#X msg 360 45 \; pd dsp 1 \; paint 1 \; doit bang \;;
+#X connect 1 0 24 0;
+#X connect 2 0 5 0;
+#X connect 2 0 24 1;
+#X connect 5 0 24 0;
+#X connect 24 0 0 0;
+#X connect 24 0 4 0;
+#X connect 25 0 24 0;
diff --git a/filters/highshelf.c b/filters/highshelf.c
new file mode 100755
index 0000000..ee6006c
--- /dev/null
+++ b/filters/highshelf.c
@@ -0,0 +1,90 @@
+/* (C) Guenter Geiger <geiger@epy.co.at> */
+
+
+/*
+
+ These filter coefficients computations are taken from
+ http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt  
+
+ written by Robert Bristow-Johnson
+
+*/
+
+#include <m_pd.h>
+#ifdef NT
+#pragma warning( disable : 4244 )
+#pragma warning( disable : 4305 )
+#endif
+#include <math.h>
+#include "filters.h"
+
+
+/* ------------------- highshelf ----------------------------*/
+
+static t_class *highshelf_class;
+
+void highshelf_bang(t_rbjfilter *x)
+{
+     t_atom at[5];
+     t_float omega = e_omega(x->x_freq,x->x_rate);
+     t_float A = e_A(x->x_gain);
+     t_float cs = cos(omega);
+     t_float sn = sin(omega);
+     t_float beta = e_beta(A,x->x_bw* 0.01);
+
+     t_float b0 =    A*((A+1) + (A-1)*cs + beta*sn);
+     t_float b1 =-2.*A*((A-1) + (A+1)*cs);
+     t_float b2 =    A*((A+1) + (A-1)*cs - beta*sn);
+     t_float a0 =      ((A+1) - (A-1)*cs + beta*sn);
+     t_float a1 =   2.*((A-1) - (A+1)*cs);
+     t_float a2 =      ((A+1) - (A-1)*cs - beta*sn);
+
+/*     post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw);*/
+     
+     if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
+       post("highshelf: filter unstable -> resetting");
+       a0=1.;a1=0.;a2=0.;
+       b0=1.;b1=0.;b2=0.;
+     }
+
+     SETFLOAT(at,-a1/a0);
+     SETFLOAT(at+1,-a2/a0);
+     SETFLOAT(at+2,b0/a0);
+     SETFLOAT(at+3,b1/a0);
+     SETFLOAT(at+4,b2/a0);
+     
+     outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
+}
+
+
+void highshelf_float(t_rbjfilter *x,t_floatarg f)
+{
+     x->x_freq = f;
+     highshelf_bang(x);
+}
+
+
+static void *highshelf_new(t_floatarg f,t_floatarg g,t_floatarg bw)
+{
+    t_rbjfilter *x = (t_rbjfilter *)pd_new(highshelf_class);
+
+    x->x_rate = 44100.0;
+    outlet_new(&x->x_obj,&s_float);
+    floatinlet_new(&x->x_obj, &x->x_gain);    
+    floatinlet_new(&x->x_obj, &x->x_bw);
+    if (f > 0.) x->x_freq = f;
+    if (bw > 0.) x->x_bw = bw;
+    if (g != 0.) x->x_gain = g;
+    return (x);
+}
+
+
+void highshelf_setup(void)
+{
+    highshelf_class = class_new(gensym("highshelf"), (t_newmethod)highshelf_new, 0,
+				sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,A_DEFFLOAT,0);
+    class_addbang(highshelf_class,highshelf_bang);
+    class_addfloat(highshelf_class,highshelf_float);
+}
+
+
diff --git a/filters/highshelf.pd b/filters/highshelf.pd
new file mode 100755
index 0000000..be2a577
--- /dev/null
+++ b/filters/highshelf.pd
@@ -0,0 +1,39 @@
+#N canvas 310 193 620 455 10;
+#X obj 77 182 print;
+#X floatatom 77 114;
+#X floatatom 186 112;
+#X msg 360 117 \; paint 0;
+#X obj 159 175 filtgain;
+#X msg 91 138 bang;
+#X text 6 334 See also:;
+#X obj 72 335 bandpass;
+#X obj 139 336 notch;
+#X obj 195 337 lowpass;
+#X obj 247 336 highpass;
+#X obj 247 358 equalizer;
+#X obj 72 357 highshelf;
+#X obj 139 357 lowshelf;
+#X obj 195 357 hlshelf;
+#X text 75 226 These filters are all controlled by a bandwidth which is expressed in octaves. A bandwidth of 100 is equivalent to one octave.;
+#X text 358 25 click first;
+#X text 208 159 click on filtgain to view frequency plot;
+#X text 6 393 (C) Guenter Geiger 2000;
+#X text 75 92 frequency;
+#X text 75 268 Attention \, only the left inlet triggers new coefficients for biquad~;
+#X floatatom 129 113;
+#X text 138 92 gain;
+#X text 71 26 ==============================================;
+#X text 186 91 slope (0 - 100);
+#X text 76 12 Highshelf coefficients for biquad~;
+#X obj 77 160 highshelf 5000 70 100;
+#X obj 30 113 r doit;
+#X msg 360 45 \; pd dsp 1 \; paint 1 \; doit bang \;;
+#X connect 1 0 26 0;
+#X connect 2 0 5 0;
+#X connect 2 0 26 2;
+#X connect 5 0 26 0;
+#X connect 21 0 5 0;
+#X connect 21 0 26 1;
+#X connect 26 0 0 0;
+#X connect 26 0 4 0;
+#X connect 27 0 26 0;
diff --git a/filters/hlshelf.c b/filters/hlshelf.c
new file mode 100755
index 0000000..a2189d7
--- /dev/null
+++ b/filters/hlshelf.c
@@ -0,0 +1,226 @@
+/* (C) Guenter Geiger <geiger@epy.co.at> */
+
+
+#include <m_pd.h>
+#include <math.h>
+
+#ifdef NT
+#pragma warning( disable : 4244 )
+#pragma warning( disable : 4305 )
+#endif
+
+/* ------------------------ hlshelf ----------------------------- */
+
+
+#ifndef M_PI
+#define M_PI 3.141593f
+#endif
+
+#define SRATE 44100.0
+#define MAX_GAIN 120.0f
+
+static t_class *hlshelf_class;
+
+
+typedef struct _hlshelf
+{
+     t_object x_obj;
+     float s_rate;
+     float s_gain0;
+     float s_gain1;
+     float s_gain2;
+     float s_ltransfq;
+     float s_htransfq;
+     float s_lradians;
+     float s_hradians;
+} t_hlshelf;
+
+
+int hlshelf_check_stability(t_float fb1,
+			    t_float fb2, 
+			    t_float ff1,
+			    t_float ff2,
+			    t_float ff3)
+{
+    float discriminant = fb1 * fb1 + 4 * fb2;
+
+    if (discriminant < 0) /* imaginary roots -- resonant filter */
+    {
+    	    /* they're conjugates so we just check that the product
+    	    is less than one */
+    	if (fb2 >= -1.0f) goto stable;
+    }
+    else    /* real roots */
+    {
+    	    /* check that the parabola 1 - fb1 x - fb2 x^2 has a
+    	    	vertex between -1 and 1, and that it's nonnegative
+    	    	at both ends, which implies both roots are in [1-,1]. */
+    	if (fb1 <= 2.0f && fb1 >= -2.0f &&
+    	    1.0f - fb1 -fb2 >= 0 && 1.0f + fb1 - fb2 >= 0)
+    	    	goto stable;
+    }
+    return 0;
+stable:
+    return 1;
+}
+
+
+void hlshelf_check(t_hlshelf *x)
+{
+
+     if(x->s_gain0 - x->s_gain1 > MAX_GAIN) {
+	  x->s_gain0 = x->s_gain1 + MAX_GAIN; 
+	  post("setting gain0 to %f",x->s_gain0);
+     }
+
+
+     if(x->s_gain1 > MAX_GAIN) {
+	  x->s_gain1 = MAX_GAIN;
+	  post("setting gain1 to %f",x->s_gain1);
+     }
+
+     if(x->s_gain2 - x->s_gain1 > MAX_GAIN) {
+	  x->s_gain2 = x->s_gain1 + MAX_GAIN; 
+	  post("setting gain2 to %f",x->s_gain2);
+     }
+
+  /* constrain: 0 <= x->s_ltransfq < x->s_htransfq. */
+     x->s_ltransfq = (x->s_ltransfq < x->s_htransfq) ? x->s_ltransfq : x->s_htransfq - 0.5f;
+     
+     if (x->s_ltransfq < 0) x->s_ltransfq = 0.0f;
+     
+     x->s_lradians = M_PI * x->s_ltransfq / x->s_rate;
+     x->s_hradians= M_PI * (0.5f - (x->s_htransfq / x->s_rate));	
+
+}
+
+
+void hlshelf_bang(t_hlshelf *x)
+{
+     t_atom at[6];
+     float c0, c1, c2, d0, d1, d2;	/* output coefs */
+     float a1, a2, b1, b2, g1, g2;	/* temp coefs */
+     double xf;
+
+     hlshelf_check(x);
+     
+     /* low shelf */
+     xf = 0.5 * 0.115129255 * (double)(x->s_gain0 - x->s_gain1); /* ln(10) / 20 = 0.115129255 */
+     if(xf < -200.) /* exp(x) -> 0 */
+     {
+	  a1 = 1.0f;
+	  b1 = -1.0f;
+	  g1 = 0.0f;
+     }
+     else
+     {
+	  double t = tan(x->s_lradians);
+	  double e = exp(xf);
+	  double r = t / e;
+	  double kr = t * e;
+	  
+	  a1 = (r - 1) / (r + 1);		
+	  b1 = (kr - 1) / (kr + 1);
+	  g1 = (kr + 1) / (r + 1);
+     }
+     
+     /* high shelf */
+     xf = 0.5 * 0.115129255 * (double)(x->s_gain2 - x->s_gain1); /* ln(10) / 20 = 0.115129255 */
+     if(xf < -200.) /* exp(x) -> 0 */
+     {
+	  a2 = -1.0f;
+	  b2 = 1.0f;
+	  g2 = 0.0f;
+     }
+     else
+     {
+	  double t = tan(x->s_hradians);
+	  double e = exp(xf);
+	  double r = t / e;
+	  double kr = t * e;
+	  
+	  a2 = (1 - r) / (1 + r);
+	  b2 = (1 - kr) / (1 + kr);
+	  g2 = (1 + kr) / (1 + r);
+     }
+     
+     /* form product */
+     c0 = g1 * g2 * (float)(exp((double)(x->s_gain1) * 0.05f * 2.302585093f));  ;
+     c1 = a1 + a2;
+     c2 = a1 * a2;
+     d0 =  1.0f;
+     d1 = b1 + b2;
+     d2 = b1 * b2;
+
+     if (!hlshelf_check_stability(-c1/d0,-c2/d0,d0/d0,d1/d0,d2/d0)) {
+       post("hlshelf: filter unstable -> resetting");
+       c0=1.;c1=0.;c2=0.;
+       d0=1.;d1=0.;d2=0.;
+     }
+
+     SETFLOAT(at,-c1/d0);
+     SETFLOAT(at+1,-c2/d0);
+     SETFLOAT(at+2,d0/d0);
+     SETFLOAT(at+3,d1/d0);
+     SETFLOAT(at+4,d2/d0);
+     
+     outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
+}
+
+void hlshelf_float(t_hlshelf *x,t_floatarg f)
+{
+     x->s_gain0 = f;
+     hlshelf_bang(x);
+}
+
+
+static void *hlshelf_new(t_symbol* s,t_int argc, t_atom* at)
+{
+    t_hlshelf *x = (t_hlshelf *)pd_new(hlshelf_class);
+    t_float k0 = atom_getfloat(at);
+    t_float k1 = atom_getfloat(at+1);
+    t_float k2 = atom_getfloat(at+2);
+    t_float f1 = atom_getfloat(at+3);
+    t_float f2 = atom_getfloat(at+4);
+
+
+    f1 = atom_getfloat(at);
+    f2 = atom_getfloat(at);
+
+    if ((f1 == 0.0f && f2 == 0.0f) || f1 > f2){ /* all gains = 0db */
+	 f1 = 150.0f;	
+	 f2 = 5000.0f;
+    }
+
+    if (f1 < 0) f1 = 0.0f;
+    if (f2 > SRATE) f2 = .5f*SRATE;
+ 
+    x->s_rate = SRATE;		/* srate default  */
+    x->s_gain0 = k0;
+    x->s_gain1 = k1;
+    x->s_gain2 = k2;
+    
+    x->s_ltransfq = 0.0f;
+    x->s_htransfq = SRATE/2;
+
+    x->s_lradians = M_PI * x->s_ltransfq / x->s_rate;
+    x->s_hradians= M_PI * (0.5f - (x->s_htransfq / x->s_rate));
+
+    floatinlet_new(&x->x_obj, &x->s_gain1);
+    floatinlet_new(&x->x_obj, &x->s_gain2);
+    floatinlet_new(&x->x_obj, &x->s_ltransfq);
+    floatinlet_new(&x->x_obj, &x->s_htransfq);
+    outlet_new(&x->x_obj, &s_list);
+
+    return (x);
+}
+
+void hlshelf_setup(void)
+{
+    hlshelf_class = class_new(gensym("hlshelf"), (t_newmethod)hlshelf_new, 0,
+				sizeof(t_hlshelf), 0, A_GIMME, 0);
+    class_addbang(hlshelf_class,hlshelf_bang);
+    class_addfloat(hlshelf_class,hlshelf_float);
+}
+
+
diff --git a/filters/hlshelf.pd b/filters/hlshelf.pd
new file mode 100755
index 0000000..0e5251d
--- /dev/null
+++ b/filters/hlshelf.pd
@@ -0,0 +1,34 @@
+#N canvas 365 183 620 471 10;
+#X obj 77 182 print;
+#X floatatom 77 114;
+#X floatatom 139 114;
+#X msg 360 109 \; paint 0;
+#X obj 159 175 filtgain;
+#X text 139 93 bandwidth (0 - 100);
+#X text 6 334 See also:;
+#X obj 72 335 bandpass;
+#X obj 139 336 notch;
+#X obj 195 337 lowpass;
+#X obj 247 336 highpass;
+#X obj 247 358 equalizer;
+#X obj 72 357 highshelf;
+#X obj 139 357 lowshelf;
+#X obj 195 357 hlshelf;
+#X text 75 226 These filters are all controlled by a bandwidth which is expressed in octaves. A bandwidth of 100 is equivalent to one octave.;
+#X text 358 25 click first;
+#X text 158 159 click on filtgain to view frequency plot;
+#X text 76 12 Bandpass coefficients for biquad~;
+#X text 70 26 ===================================;
+#X text 6 393 (C) Guenter Geiger 2000;
+#X text 75 92 frequency;
+#X text 75 268 Attention \, only the left inlet triggers new coefficients for biquad~;
+#X obj 77 61 r freq;
+#X obj 139 61 r bw;
+#X msg 360 45 \; pd dsp 1 \; paint 1 \; freq 4000 \; bw 33;
+#X obj 77 160 hlshelf;
+#X connect 1 0 26 0;
+#X connect 2 0 26 1;
+#X connect 23 0 1 0;
+#X connect 24 0 2 0;
+#X connect 26 0 0 0;
+#X connect 26 0 4 0;
diff --git a/filters/lowpass.c b/filters/lowpass.c
new file mode 100755
index 0000000..4e1b2b9
--- /dev/null
+++ b/filters/lowpass.c
@@ -0,0 +1,89 @@
+/* (C) Guenter Geiger <geiger@epy.co.at> */
+
+
+/*
+
+ These filter coefficients computations are taken from
+ http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt  
+
+ written by Robert Bristow-Johnson
+
+*/
+
+#include <m_pd.h>
+#ifdef NT
+#pragma warning( disable : 4244 )
+#pragma warning( disable : 4305 )
+#endif
+#include <math.h>
+#include "filters.h"
+
+
+
+/* ------------------- lowpass ----------------------------*/
+
+static t_class *lowpass_class;
+
+void lowpass_bang(t_rbjfilter *x)
+{
+     t_atom at[5];
+     t_float omega = e_omega(x->x_freq,x->x_rate);
+     t_float alpha = e_alpha(x->x_bw*0.01,omega);
+     t_float b1 = 1 - cos(omega);
+     t_float b0 = b1/2.;
+     t_float b2 = b0;
+     t_float a0 = 1 + alpha;
+     t_float a1 = -2.*cos(omega);
+     t_float a2 = 1 - alpha;
+
+/*     post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw); */
+     
+     if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
+       post("lowpass: filter unstable -> resetting");
+       a0=1.;a1=0.;a2=0.;
+       b0=1.;b1=0.;b2=0.;
+     }
+
+     SETFLOAT(at,-a1/a0);
+     SETFLOAT(at+1,-a2/a0);
+     SETFLOAT(at+2,b0/a0);
+     SETFLOAT(at+3,b1/a0);
+     SETFLOAT(at+4,b2/a0);
+     
+     outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
+}
+
+
+void lowpass_float(t_rbjfilter *x,t_floatarg f)
+{
+     x->x_freq = f;
+     lowpass_bang(x);
+}
+
+
+static void *lowpass_new(t_floatarg f,t_floatarg bw)
+{
+    t_rbjfilter *x = (t_rbjfilter *)pd_new(lowpass_class);
+
+    x->x_rate = 44100.0;
+    outlet_new(&x->x_obj,&s_float);
+/*    floatinlet_new(&x->x_obj, &x->x_gain);     */
+    floatinlet_new(&x->x_obj, &x->x_bw);
+
+    if (f > 0.) x->x_freq = f;
+    if (bw > 0.) x->x_bw = bw;
+    return (x);
+}
+
+
+void lowpass_setup(void)
+{
+    lowpass_class = class_new(gensym("lowpass"), (t_newmethod)lowpass_new, 0,
+				sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,0);
+    class_addbang(lowpass_class,lowpass_bang);
+    class_addfloat(lowpass_class,lowpass_float);
+}
+
+
+
+
diff --git a/filters/lowpass.pd b/filters/lowpass.pd
new file mode 100755
index 0000000..9d15c16
--- /dev/null
+++ b/filters/lowpass.pd
@@ -0,0 +1,35 @@
+#N canvas 365 183 620 467 10;
+#X obj 77 182 print;
+#X floatatom 77 114;
+#X floatatom 162 114;
+#X msg 360 109 \; paint 0;
+#X obj 159 175 filtgain;
+#X msg 91 138 bang;
+#X text 139 93 bandwidth (0 - 100);
+#X text 6 334 See also:;
+#X obj 72 335 bandpass;
+#X obj 139 336 notch;
+#X obj 195 337 lowpass;
+#X obj 247 336 highpass;
+#X obj 247 358 equalizer;
+#X obj 72 357 highshelf;
+#X obj 139 357 lowshelf;
+#X obj 195 357 hlshelf;
+#X text 75 226 These filters are all controlled by a bandwidth which is expressed in octaves. A bandwidth of 100 is equivalent to one octave.;
+#X text 358 25 click first;
+#X text 175 159 click on filtgain to view frequency plot;
+#X text 70 26 ===================================;
+#X text 6 393 (C) Guenter Geiger 2000;
+#X text 75 92 frequency;
+#X text 75 268 Attention \, only the left inlet triggers new coefficients for biquad~;
+#X text 71 12 Lowpass coefficients for biquad~;
+#X msg 360 45 \; pd dsp 1 \; paint 1 \; doit bang \;;
+#X obj 32 114 r doit;
+#X obj 77 160 lowpass 4000 33;
+#X connect 1 0 26 0;
+#X connect 2 0 5 0;
+#X connect 2 0 26 1;
+#X connect 5 0 26 0;
+#X connect 25 0 26 0;
+#X connect 26 0 0 0;
+#X connect 26 0 4 0;
diff --git a/filters/lowshelf.c b/filters/lowshelf.c
new file mode 100755
index 0000000..dd925dc
--- /dev/null
+++ b/filters/lowshelf.c
@@ -0,0 +1,91 @@
+/* (C) Guenter Geiger <geiger@epy.co.at> */
+
+
+/*
+
+ These filter coefficients computations are taken from
+ http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt  
+
+ written by Robert Bristow-Johnson
+
+*/
+
+#include <m_pd.h>
+#ifdef NT
+#pragma warning( disable : 4244 )
+#pragma warning( disable : 4305 )
+#endif
+#include <math.h>
+#include "filters.h"
+
+
+
+/* ------------------- lowshelf ----------------------------*/
+
+static t_class *lowshelf_class;
+
+void lowshelf_bang(t_rbjfilter *x)
+{
+     t_atom at[5];
+     t_float omega = e_omega(x->x_freq,x->x_rate);
+     t_float A = e_A(x->x_gain);
+     t_float cs = cos(omega);
+     t_float sn = sin(omega);
+     t_float beta = e_beta(A,x->x_bw*0.01);
+
+     t_float b0 =    A*((A+1) - (A-1)*cs + beta*sn);
+     t_float b1 = 2.*A*((A-1) - (A+1)*cs);
+     t_float b2 =    A*((A+1) - (A-1)*cs - beta*sn);
+     t_float a0 =      ((A+1) + (A-1)*cs + beta*sn);
+     t_float a1 =  -2.*((A-1) + (A+1)*cs);
+     t_float a2 =      ((A+1) + (A-1)*cs - beta*sn);
+
+/*     post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw); */
+     
+     if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
+       post("lowshelf: filter unstable -> resetting");
+       a0=1.;a1=0.;a2=0.;
+       b0=1.;b1=0.;b2=0.;
+     }
+
+     SETFLOAT(at,-a1/a0);
+     SETFLOAT(at+1,-a2/a0);
+     SETFLOAT(at+2,b0/a0);
+     SETFLOAT(at+3,b1/a0);
+     SETFLOAT(at+4,b2/a0);
+     
+     outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
+}
+
+
+void lowshelf_float(t_rbjfilter *x,t_floatarg f)
+{
+     x->x_freq = f;
+     lowshelf_bang(x);
+}
+
+
+static void *lowshelf_new(t_floatarg f,t_floatarg g,t_floatarg bw)
+{
+    t_rbjfilter *x = (t_rbjfilter *)pd_new(lowshelf_class);
+
+    x->x_rate = 44100.0;
+    outlet_new(&x->x_obj,&s_float);
+    floatinlet_new(&x->x_obj, &x->x_gain);    
+    floatinlet_new(&x->x_obj, &x->x_bw);
+    if (f > 0.) x->x_freq = f;
+    if (bw > 0.) x->x_bw = bw;
+    if (g != 0.) x->x_gain = g;
+    return (x);
+}
+
+
+void lowshelf_setup(void)
+{
+    lowshelf_class = class_new(gensym("lowshelf"), (t_newmethod)lowshelf_new, 0,
+				sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,A_DEFFLOAT,0);
+    class_addbang(lowshelf_class,lowshelf_bang);
+    class_addfloat(lowshelf_class,lowshelf_float);
+}
+
+
diff --git a/filters/lowshelf.pd b/filters/lowshelf.pd
new file mode 100755
index 0000000..140c754
--- /dev/null
+++ b/filters/lowshelf.pd
@@ -0,0 +1,39 @@
+#N canvas 365 183 620 459 10;
+#X obj 77 182 print;
+#X floatatom 77 114;
+#X floatatom 192 113;
+#X msg 360 117 \; paint 0;
+#X obj 159 175 filtgain;
+#X msg 91 138 bang;
+#X text 6 334 See also:;
+#X obj 72 335 bandpass;
+#X obj 139 336 notch;
+#X obj 195 337 lowpass;
+#X obj 247 336 highpass;
+#X obj 247 358 equalizer;
+#X obj 72 357 highshelf;
+#X obj 139 357 lowshelf;
+#X obj 195 357 hlshelf;
+#X text 75 226 These filters are all controlled by a bandwidth which is expressed in octaves. A bandwidth of 100 is equivalent to one octave.;
+#X text 358 25 click first;
+#X text 211 159 click on filtgain to view frequency plot;
+#X text 6 393 (C) Guenter Geiger 2000;
+#X text 75 92 frequency;
+#X text 75 268 Attention \, only the left inlet triggers new coefficients for biquad~;
+#X floatatom 129 113;
+#X text 138 92 gain;
+#X text 71 26 ==============================================;
+#X text 192 92 slope (0 - 100);
+#X text 76 12 Lowshelf coefficients for biquad~;
+#X obj 31 113 r doit;
+#X msg 360 45 \; pd dsp 1 \; paint 1 \; doit bang \;;
+#X obj 77 160 lowshelf 4000 50 100;
+#X connect 1 0 28 0;
+#X connect 2 0 5 0;
+#X connect 2 0 28 2;
+#X connect 5 0 28 0;
+#X connect 21 0 5 0;
+#X connect 21 0 28 1;
+#X connect 26 0 28 0;
+#X connect 28 0 0 0;
+#X connect 28 0 4 0;
diff --git a/filters/moog~.c b/filters/moog~.c
new file mode 100755
index 0000000..924ff31
--- /dev/null
+++ b/filters/moog~.c
@@ -0,0 +1,182 @@
+/* (C) Guenter Geiger <geiger@epy.co.at> */
+
+
+#include "math.h"
+#include <m_pd.h>
+
+/* ----------------------------- moog ----------------------------- */
+static t_class *moog_class;
+
+
+typedef struct _moog
+{
+     t_object x_obj;
+  t_pd   in2;
+     t_float x_1,x_2,x_3,x_4;
+     t_float y_1,y_2,y_3,y_4;
+} t_moog;
+
+static void moog_reset(t_moog *x)
+{
+	x->x_1 = x->x_2 = x->x_3 = x->x_4 = 0.0;
+	x->y_1 = x->y_2 = x->y_3 = x->y_4 = 0.0;
+
+}
+
+
+
+static void *moog_new(t_symbol *s, int argc, t_atom *argv)
+{
+    if (argc > 1) post("moog~: extra arguments ignored");
+    {
+	t_moog *x = (t_moog *)pd_new(moog_class);
+	outlet_new(&x->x_obj, &s_signal);
+	inlet_new(&x->x_obj, &x->x_obj.ob_pd, &s_signal, &s_signal);
+	inlet_new(&x->x_obj, &x->in2, &s_signal, &s_signal);
+	moog_reset(x);
+	return (x);
+    }
+
+
+}
+
+
+
+static t_float calc_k(t_float f,t_float k) {
+  if (k>4.) k =4.;
+  if (k < 0.) k = 0.;
+  if (f <= 3800) return k;
+  k = k - 0.5*((f-3800)/4300);
+  return k;
+}
+
+t_int *moog_perform(t_int *w)
+{
+    t_moog* x = (t_moog*) (w[1]); 
+    t_float *in1 = (t_float *)(w[2]);
+    t_float *p = (t_float *)(w[3]);
+    t_float *k = (t_float *)(w[4]);
+
+    t_float *out = (t_float *)(w[5]);
+    int n = (int)(w[6]);
+    float in;
+    float pt,pt1;
+    
+    float x1 = x->x_1;
+    float x2 = x->x_2;
+    float x3 = x->x_3;
+    float x4 = x->x_4;
+    float y1 = x->y_1;
+    float y2 = x->y_2;
+    float y3 = x->y_3;
+    float y4 = x->y_4;
+
+
+   while (n--) {
+     if (*p > 8140) *p = 8140.;
+     *k = calc_k(*p,*k);
+     pt =*p;
+     pt1=(pt+1)*0.76923077;
+     in = *in1++ - *k*y4;
+     y1 = (pt1)*in + 0.3*x1 - pt*y1;
+     x1 = in;
+     y2 = (pt1)*y1 + 0.3*x2 - pt*y2;
+     x2 = y1;
+     y3 = (pt1)*y2 + 0.3 *x3 - pt*y3;
+     x3 = y2;
+     y4 = (pt1)*y3 + 0.3*x4 - pt*y4;
+     x4 = y3;
+     *out++ = y4;
+   }
+
+   
+    x->y_1 = y1;
+    x->y_2 = y2;
+    x->y_3 = y3;
+    x->y_4 = y4;
+    x->x_1 = x1;
+    x->x_2 = x2;
+    x->x_3 = x3;
+    x->x_4 = x4;
+
+    return (w+7);
+}
+
+
+#define CLIP(x)  x = ((x) > 1.0 ? (1.0) : (x))
+
+t_int *moog_perf8(t_int *w)
+{
+    t_moog* x = (t_moog*) (w[1]); 
+    t_float *in1 = (t_float *)(w[2]);
+    t_float *p = (t_float *)(w[3]);
+    t_float *k = (t_float *)(w[4]);
+    t_float *out = (t_float *)(w[5]);
+    int n = (int)(w[6]);
+
+    t_float x1 = x->x_1;
+    t_float x2 = x->x_2;
+    t_float x3 = x->x_3;
+    t_float x4 = x->x_4;
+    t_float y1 = x->y_1;
+    t_float y2 = x->y_2;
+    t_float y3 = x->y_3;
+    t_float y4 = x->y_4;
+    t_float temp,temp2;
+    t_float pt,pt1;
+    t_float in;
+
+    while (n--) {
+      if (*p > 8140.) *p = 8140.;
+      *k = calc_k(*p,*k);
+
+     pt =*p* 0.01*0.0140845 - 0.9999999f;
+     pt1=(pt+1.0)*0.76923077;
+     in = *in1++ - *k*y4;
+     y1 = pt1*(in + 0.3*x1) - pt*y1;
+     x1 = in;
+     y2 = pt1*(y1 + 0.3*x2) - pt*y2;
+     x2 = y1;
+     y3 = pt1*(y2 + 0.3*x3) - pt*y3;
+     x3 = y2;
+     y4 = pt1*(y3 + 0.3*x4) - pt*y4;
+     x4 = y3;
+     *out++ = y4;
+
+      p++;k++;
+    }
+
+    x->y_1 = y1;
+    x->y_2 = y2;
+    x->y_3 = y3;
+    x->y_4 = y4;
+    x->x_1 = x1;
+    x->x_2 = x2;
+    x->x_3 = x3;
+    x->x_4 = x4;
+    
+    return (w+7);
+}
+
+void dsp_add_moog(t_moog *x, t_sample *in1, t_sample *in2, t_sample *in3, t_sample *out, int n)
+{
+    if (n&7)
+    	dsp_add(moog_perform, 6,(t_int)x, in1,in2,in3, out, n);
+    else	
+    	dsp_add(moog_perf8, 6,(t_int) x, in1, in2, in3, out, n);
+}
+
+static void moog_dsp(t_moog *x, t_signal **sp)
+{
+    dsp_add_moog(x,sp[0]->s_vec, sp[1]->s_vec, sp[2]->s_vec, sp[3]->s_vec,sp[0]->s_n);
+}
+
+
+void moog_tilde_setup(void)
+{
+    moog_class = class_new(gensym("moog~"), (t_newmethod)moog_new, 0,
+    	sizeof(t_moog), 0, A_GIMME, 0);
+    class_addmethod(moog_class, nullfn, gensym("signal"), 0);
+    class_addmethod(moog_class, (t_method)moog_reset, gensym("reset"), 0);
+    class_addmethod(moog_class, (t_method)moog_dsp, gensym("dsp"), A_NULL);
+}
diff --git a/filters/moog~.pd b/filters/moog~.pd
new file mode 100755
index 0000000..7e0139b
--- /dev/null
+++ b/filters/moog~.pd
@@ -0,0 +1,39 @@
+#N canvas 225 113 568 397 10;
+#X obj 186 210 moog~;
+#X obj 178 288 dac~;
+#X floatatom 226 163 5 0 0;
+#X floatatom 183 104 5 0 0;
+#X floatatom 25 113 5 0 0;
+#X obj 238 237 env~;
+#X floatatom 238 257 5 0 0;
+#X obj 186 257 *~ 0.1;
+#X msg 182 163 reset;
+#X obj 116 105 +~ 1;
+#X floatatom 116 63 5 0 0;
+#X floatatom 180 128 5 0 0;
+#X obj 116 146 +~ 100;
+#X obj 116 84 osc~ 0.25;
+#X obj 116 125 *~ 2000;
+#X obj 226 182 sig~ 3;
+#X obj 25 139 phasor~ 110;
+#X msg 249 52 \; pd dsp 1 \;;
+#X text 17 7 A signal controlled "moog" resonant lowpass;
+#X text 272 163 Q (1-4);
+#X text 61 46 resonance freq modulation;
+#X connect 0 0 5 0;
+#X connect 0 0 7 0;
+#X connect 2 0 15 0;
+#X connect 3 0 14 1;
+#X connect 4 0 16 0;
+#X connect 5 0 6 0;
+#X connect 7 0 1 0;
+#X connect 7 0 1 1;
+#X connect 8 0 0 0;
+#X connect 9 0 14 0;
+#X connect 10 0 13 0;
+#X connect 11 0 12 1;
+#X connect 12 0 0 1;
+#X connect 13 0 9 0;
+#X connect 14 0 12 0;
+#X connect 15 0 0 2;
+#X connect 16 0 0 0;
diff --git a/filters/notch.c b/filters/notch.c
new file mode 100755
index 0000000..ab11a7a
--- /dev/null
+++ b/filters/notch.c
@@ -0,0 +1,89 @@
+/* (C) Guenter Geiger <geiger@epy.co.at> */
+
+
+/*
+
+ These filter coefficients computations are taken from
+ http://www.harmony-central.com/Computer/Programming/Audio-EQ-Cookbook.txt  
+
+ written by Robert Bristow-Johnson
+
+*/
+
+#include <m_pd.h>
+#ifdef NT
+#pragma warning( disable : 4244 )
+#pragma warning( disable : 4305 )
+#endif
+#include <math.h>
+#include "filters.h"
+
+
+
+/* ------------------- notch ----------------------------*/
+
+static t_class *notch_class;
+
+void notch_bang(t_rbjfilter *x)
+{
+     t_atom at[5];
+     t_float omega = e_omega(x->x_freq,x->x_rate);
+     t_float alpha = e_alpha(x->x_bw* 0.01,omega);
+     t_float b1 = -2.*cos(omega);
+     t_float b0 = 1;
+     t_float b2 = b0;
+     t_float a0 = 1 + alpha;
+     t_float a1 = -2.*cos(omega);
+     t_float a2 = 1 - alpha;
+
+/*     post("bang %f %f %f",x->x_freq, x->x_gain, x->x_bw); */
+     
+     if (!check_stability(-a1/a0,-a2/a0,b0/a0,b1/a0,b2/a0)) {
+       post("notch: filter unstable -> resetting");
+       a0=1.;a1=0.;a2=0.;
+       b0=1.;b1=0.;b2=0.;
+     }
+
+     SETFLOAT(at,-a1/a0);
+     SETFLOAT(at+1,-a2/a0);
+     SETFLOAT(at+2,b0/a0);
+     SETFLOAT(at+3,b1/a0);
+     SETFLOAT(at+4,b2/a0);
+     
+     outlet_list(x->x_obj.ob_outlet,&s_list,5,at);
+}
+
+
+void notch_float(t_rbjfilter *x,t_floatarg f)
+{
+     x->x_freq = f;
+     notch_bang(x);
+}
+
+
+static void *notch_new(t_floatarg f,t_floatarg bw)
+{
+    t_rbjfilter *x = (t_rbjfilter *)pd_new(notch_class);
+
+    x->x_rate = 44100.0;
+    outlet_new(&x->x_obj,&s_float);
+/*    floatinlet_new(&x->x_obj, &x->x_gain);    */
+    floatinlet_new(&x->x_obj, &x->x_bw);
+    if (f > 0.) x->x_freq = f;
+    if (bw > 0.) x->x_bw = bw;
+    return (x);
+}
+
+
+void notch_setup(void)
+{
+    notch_class = class_new(gensym("notch"), (t_newmethod)notch_new, 0,
+				sizeof(t_rbjfilter), 0,A_DEFFLOAT,A_DEFFLOAT,0);
+    class_addbang(notch_class,notch_bang);
+    class_addfloat(notch_class,notch_float);
+}
+
+
+
+
+
diff --git a/filters/notch.pd b/filters/notch.pd
new file mode 100755
index 0000000..a65d9c4
--- /dev/null
+++ b/filters/notch.pd
@@ -0,0 +1,35 @@
+#N canvas 363 47 620 467 10;
+#X obj 77 182 print;
+#X floatatom 77 114;
+#X floatatom 150 114;
+#X msg 360 109 \; paint 0;
+#X obj 159 175 filtgain;
+#X msg 91 138 bang;
+#X text 150 93 bandwidth (0 - 100);
+#X text 6 334 See also:;
+#X obj 72 335 bandpass;
+#X obj 139 336 notch;
+#X obj 195 337 lowpass;
+#X obj 247 336 highpass;
+#X obj 247 358 equalizer;
+#X obj 72 357 highshelf;
+#X obj 139 357 lowshelf;
+#X obj 195 357 hlshelf;
+#X text 75 226 These filters are all controlled by a bandwidth which is expressed in octaves. A bandwidth of 100 is equivalent to one octave.;
+#X text 358 25 click first;
+#X text 165 159 click on filtgain to view frequency plot;
+#X text 70 26 ===================================;
+#X text 6 393 (C) Guenter Geiger 2000;
+#X text 75 92 frequency;
+#X text 75 268 Attention \, only the left inlet triggers new coefficients for biquad~;
+#X text 72 13 Notch coefficients for biquad~;
+#X msg 360 46 \; pd dsp 1 \; paint 1 \; doit bang \;;
+#X obj 35 114 r doit;
+#X obj 77 160 notch 4000 33;
+#X connect 1 0 26 0;
+#X connect 2 0 5 0;
+#X connect 2 0 26 1;
+#X connect 5 0 26 0;
+#X connect 25 0 26 0;
+#X connect 26 0 0 0;
+#X connect 26 0 4 0;
-- 
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