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OBXd LPF implementation

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asb2m10 11 years ago
parent 36bd40be31
commit 3f7c793745
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  1. BIN
      Builds/MacOSX/Dexed.xcodeproj/project.xcworkspace/xcuserdata/asb2m10.xcuserdatad/UserInterfaceState.xcuserstate
  2. 16
      README.md
  3. 231
      Source/PluginFx.cpp
  4. 64
      Source/PluginFx.h

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Builds/MacOSX/Dexed.xcodeproj/project.xcworkspace/xcuserdata/asb2m10.xcuserdatad/UserInterfaceState.xcuserstate generated
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16
README.md
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@ -22,6 +22,12 @@ Features
* Each operator have a realtime VU meter to know wich one is active * Each operator have a realtime VU meter to know wich one is active
* Can load/save any DX7/TX7 sysex programs. It is also possible to save a single program into a different sysex file. * Can load/save any DX7/TX7 sysex programs. It is also possible to save a single program into a different sysex file.
Changelog
---------
* Version 0.4.0 (current sprint)
** Modulatioin wheel support
** Now using the [OBxd](https://obxd.wordpress.com) 4-pole lowpass filter implementation
Binary downloads Binary downloads
---------------- ----------------
Dexed is not a finished product but it is stable enough to be used in a DAW environment: Dexed is not a finished product but it is stable enough to be used in a DAW environment:
@ -51,18 +57,18 @@ valid checksum for your DX7 keyboard. I'm in now way responsible if this breaks
Credits & thanks Credits & thanks
---------------- ----------------
Raph Levien and the msfa team, markusthegeek, Jean-Marc Desprez and all the crew who made these historic * DX Synth engine : Raph Levien and the [msfa](https://code.google.com/p/music-synthesizer-for-android) team
DX programs: (Dave Benson, Frank Carvalho, Tim Conrardy, Jack Deckard, Chris Dodunski, Tim Garrett, * LP Filter : Filatov Vadim (2DaT); taken from the excellent [OBxd](https://obxd.wordpress.com) project
Hitaye, Stephan Ibsen, Christian Jezreel, Narfman, Godric Wilkie) * Original DX7 compilation : Jean-Marc Desprez [SynprezFM](http://www.synprez.com/SynprezFM) and to all the all crew who made these historic DX programs: Dave Benson, Frank Carvalho, Tim Conrardy, Jack Deckard, Chris Dodunski, Tim Garrett, Hitaye, Stephan Ibsen, Christian Jezreel, Narfman, Godric Wilkie
* markusthegeek direct implication for this project
TODO - Dexed TODO - Dexed
------------ ------------
* Implement a better DX look and feel (amp, pitch, algo) * Implement a better DX look and feel (amp, pitch, algo)
* Better implementation of the LPF filter
* Various code cleanup * Various code cleanup
* Standalone executable (for full support of the editor) * Standalone executable (for full support of the editor)
TODO - msfa TODO - msfa
----------- -----------
* LFO Amplitude * LFO/Mod-wheel Amplitude
* Algo 4 & 6 feedback * Algo 4 & 6 feedback

231
Source/PluginFx.cpp
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@ -1,95 +1,194 @@
/* /**
============================================================================== *
* Copyright (c) 2013-2014 Pascal Gauthier.
PluginFx.cpp * Copyright (C) 2013-2014 Filatov Vadim.
Created: 26 Dec 2013 7:13:29pm *
Author: Pascal Gauthier * Filter taken from the OBXd project :
* https://github.com/2DaT/Obxd
The LPF is taken from the PD moog~ object. (David Lowenfels) *
Code is based off of Tim Stilson's moog filter code * This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA.
*/
==============================================================================
*/
#define _USE_MATH_DEFINES #define _USE_MATH_DEFINES
#include <math.h> #include <math.h>
#include "PluginFx.h" #include "PluginFx.h"
#include "PluginProcessor.h" #include "PluginProcessor.h"
static float gaintable[199] = { const float dc = 1e-18;
0.999969, 0.990082, 0.980347, 0.970764, 0.961304, 0.951996, 0.94281, 0.933777, 0.924866, 0.916077, 0.90741, 0.898865, 0.890442,
0.882141, 0.873962, 0.865906, 0.857941, 0.850067, 0.842346, 0.834686, 0.827148, 0.819733, 0.812378, 0.805145, 0.798004, 0.790955,
0.783997, 0.77713, 0.770355, 0.763672, 0.75708 , 0.75058, 0.744141, 0.737793, 0.731537, 0.725342, 0.719238, 0.713196, 0.707245,
0.701355, 0.695557, 0.689819, 0.684174, 0.678558, 0.673035, 0.667572, 0.66217, 0.65686, 0.651581, 0.646393, 0.641235, 0.636169,
0.631134, 0.62619, 0.621277, 0.616425, 0.611633, 0.606903, 0.602234, 0.597626, 0.593048, 0.588531, 0.584045, 0.579651, 0.575287,
0.570953, 0.566681, 0.562469, 0.558289, 0.554169, 0.550079, 0.546051, 0.542053, 0.538116, 0.53421, 0.530334, 0.52652, 0.522736,
0.518982, 0.515289, 0.511627, 0.507996 , 0.504425, 0.500885, 0.497375, 0.493896, 0.490448, 0.487061, 0.483704, 0.480377, 0.477081,
0.473816, 0.470581, 0.467377, 0.464203, 0.46109, 0.457977, 0.454926, 0.451874, 0.448883, 0.445892, 0.442932, 0.440033, 0.437134,
0.434265, 0.431427, 0.428619, 0.425842, 0.423096, 0.42038, 0.417664, 0.415009, 0.412354, 0.409729, 0.407135, 0.404572, 0.402008,
0.399506, 0.397003, 0.394501, 0.392059, 0.389618, 0.387207, 0.384827, 0.382477, 0.380127, 0.377808, 0.375488, 0.37323, 0.370972,
0.368713, 0.366516, 0.364319, 0.362122, 0.359985, 0.357849, 0.355713, 0.353607, 0.351532, 0.349457, 0.347412, 0.345398, 0.343384,
0.34137, 0.339417, 0.337463, 0.33551, 0.333588, 0.331665, 0.329773, 0.327911, 0.32605, 0.324188, 0.322357, 0.320557, 0.318756,
0.316986, 0.315216, 0.313446, 0.311707, 0.309998, 0.308289, 0.30658, 0.304901, 0.303223, 0.301575, 0.299927, 0.298309, 0.296692,
0.295074, 0.293488, 0.291931, 0.290375, 0.288818, 0.287262, 0.285736, 0.284241, 0.282715, 0.28125, 0.279755, 0.27829, 0.276825,
0.275391, 0.273956, 0.272552, 0.271118, 0.269745, 0.268341, 0.266968, 0.265594, 0.264252, 0.262909, 0.261566, 0.260223, 0.258911,
0.257599, 0.256317, 0.255035, 0.25375
};
static inline float saturate(float input) { //clamp without branching inline static float tptpc(float& state,float inp,float cutoff) {
#define _limit 0.95 double v = (inp - state) * cutoff / (1 + cutoff);
float x1 = fabsf( input + _limit ); double res = v + state;
float x2 = fabsf( input - _limit ); state = res + v;
return 0.5 * (x1 - x2); return res;
} }
static inline float crossfade(float amount, float a, float b) { inline static float tptlpupw(float & state , float inp , float cutoff , float srInv) {
return (1-amount) * a + amount * b; cutoff = (cutoff * srInv)*juce::float_Pi;
double v = (inp - state) * cutoff / (1 + cutoff);
double res = v + state;
state = res + v;
return res;
} }
void PluginFx::init(int sampleRate) { static float linsc(float param,const float min,const float max) {
return (param) * (max - min) + min;
}
static float logsc(float param, const float min,const float max,const float rolloff = 19.0f) {
return ((expf(param * logf(rolloff+1)) - 1.0f) / (rolloff)) * (max-min) + min;
}
void PluginFx::init(int sr) {
mm=0;
s1=s2=s3=s4=c=d=0;
R24=0;
mmch = (int)(mm * 3);
mmt = mm*3-mmch;
sampleRate = sr;
sampleRateInv = 1/sampleRate;
float rcrate =sqrt((44000/sampleRate));
rcor24 = (970.0 / 44000)*rcrate;
rcor24Inv = 1 / rcor24;
bright = tan((sampleRate*0.5f-10) * juce::float_Pi * sampleRateInv);
R = 1;
rcor = (480.0 / 44000)*rcrate;
rcorInv = 1 / rcor;
bandPassSw = false;
uiCutoff = 1; uiCutoff = 1;
uiReso = 0; uiReso = 0;
srate = sampleRate;
output = 0; pCutoff = -1;
for(int i=0;i<4;i++) pReso = -1;
state[i] = 0;
} }
void PluginFx::process(float *work, int sampleSize) { inline float PluginFx::NR24(float sample,float g,float lpc) {
float ml = 1 / (1+g);
float S = (lpc*(lpc*(lpc*s1 + s2) + s3) +s4)*ml;
float G = lpc*lpc*lpc*lpc;
float y = (sample - R24 * S) / (1 + R24*G);
return y + 1e-8;
};
inline float PluginFx::NR(float sample, float g) {
float y = ((sample- R * s1*2 - g*s1 - s2)/(1+ g*(2*R + g))) + dc;
return y;
}
void PluginFx::process(float *work, int sampleSize) {
// don't apply the LPF if the cutoff is to maximum // don't apply the LPF if the cutoff is to maximum
if ( uiCutoff == 1 ) if ( uiCutoff == 1 )
return; return;
// the UI values haved changed if ( uiCutoff != pCutoff || uiReso != pReso ) {
if ( uiCutoff != pCutoff || uiReso != pReso) { rReso = (0.991-logsc(1-uiReso,0,0.991,40));
// calc cutoff R24 = 3.5 * rReso;
// mel scale freq : http://www.speech.kth.se/~giampi/auditoryscales/
float freqCutoff = 700 * (pow(M_E,(uiCutoff*4000/1127)-1)) + 20; float cutoffNorm = logsc(uiCutoff,60,19000,30);
float fc = 2 * freqCutoff / srate; rCutoff = (float)tan(cutoffNorm * sampleRateInv * juce::float_Pi);
float x2 = fc*fc;
float x3 = fc*x2;
p = -0.69346 * x3 - 0.59515 * x2 + 3.2937 * fc - 1.0072; //cubic fit
// calc reso
float ix = p * 99;
int ixint = floor( ix );
float ixfrac = ix - ixint;
Q = uiReso * crossfade( ixfrac, gaintable[ ixint + 99 ], gaintable[ ixint + 100 ] );
pCutoff = uiCutoff; pCutoff = uiCutoff;
pReso = uiReso; pReso = uiReso;
R = 1 - rReso;
} }
for (int i=0; i < sampleSize; i++ ) { // THIS IS MY FAVORITE 4POLE OBXd filter
output = 0.10 * ( work[i] - output ); //negative feedback
for(int pole=0; pole < 4; pole++) { // maybe smooth this value
float temp = state[pole]; float g = rCutoff;
output = saturate( output + p * (output - temp));
state[pole] = output; for(int i=0; i < sampleSize; i++ ) {
output = saturate( output + temp ); float s = work[i];
s = s - 0.45*tptlpupw(c,s,15,sampleRateInv);
s = tptpc(d,s,bright);
float lpc = g / (1 + g);
float y0 = NR24(s,g,lpc);
//first low pass in cascade
double v = (y0 - s1) * lpc;
double res = v + s1;
s1 = res + v;
//damping
s1 =atan(s1*rcor24)*rcor24Inv;
float y1= res;
float y2 = tptpc(s2,y1,g);
float y3 = tptpc(s3,y2,g);
float y4 = tptpc(s4,y3,g);
float mc;
switch(mmch) {
case 0:
mc = ((1 - mmt) * y4 + (mmt) * y3);
break;
case 1:
mc = ((1 - mmt) * y3 + (mmt) * y2);
break;
case 2:
mc = ((1 - mmt) * y2 + (mmt) * y1);
break;
case 3:
mc = y1;
break;
} }
work[i] = output;
output *= Q; //scale the feedback //half volume comp
work[i] = mc * (1 + R24 * 0.45);
} }
} }
/*
// THIS IS THE 2POLE FILTER
for(int i=0; i < sampleSize; i++ ) {
float s = work[i];
s = s - 0.45*tptlpupw(c,s,15,sampleRateInv);
s = tptpc(d,s,bright);
//float v = ((sample- R * s1*2 - g2*s1 - s2)/(1+ R*g1*2 + g1*g2));
float v = NR(s,g);
float y1 = v*g + s1;
//damping
s1 = atan(s1 * rcor) * rcorInv;
float y2 = y1*g + s2;
s2 = y2 + y1*g;
double mc;
if(!bandPassSw)
mc = (1-mm)*y2 + (mm)*v;
else
{
mc =2 * ( mm < 0.5 ?
((0.5 - mm) * y2 + (mm) * y1):
((1-mm) * y1 + (mm-0.5) * v)
);
}
work[i] = mc;
}
*/

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Source/PluginFx.h
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@ -1,29 +1,59 @@
/* /**
============================================================================== *
* Copyright (c) 2013 Pascal Gauthier.
PluginFx.h *
Created: 26 Dec 2013 7:13:29pm * This program is free software; you can redistribute it and/or
Author: Pascal Gauthier * modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
============================================================================== * the License, or (at your option) any later version.
*/ *
* This program is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA.
*/
#ifndef PLUGINFX_H_INCLUDED #ifndef PLUGINFX_H_INCLUDED
#define PLUGINFX_H_INCLUDED #define PLUGINFX_H_INCLUDED
class PluginFx { class PluginFx {
/** float s1,s2,s3,s4;
* Used for the 4pole LFP float sampleRate;
*/ float sampleRateInv;
// process and ui values float d, c;
float R24;
float rcor24,rcor24Inv;
float bright;
//24 db multimode
float mm;
float mmt;
int mmch;
inline float NR24(float sample,float g,float lpc);
// preprocess value from the UI
float rCutoff;
float rReso;
// thread values; if these are different from the UI,
// it needs to be recalculated.
float pReso; float pReso;
float pCutoff; float pCutoff;
float p, Q;
int srate; // I am still keeping the 2pole w/multimode filter
float state[4]; inline float NR(float sample, float g);
float output; bool bandPassSw;
float rcor,rcorInv;
int R;
public: public:
// this is set directly by the ui / parameter
float uiCutoff; float uiCutoff;
float uiReso; float uiReso;

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