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95 lines
4.3 KiB
95 lines
4.3 KiB
/*
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==============================================================================
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PluginFx.cpp
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Created: 26 Dec 2013 7:13:29pm
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Author: Pascal Gauthier
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The LPF is taken from the PD moog~ object. (David Lowenfels)
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Code is based off of Tim Stilson's moog filter code
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==============================================================================
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*/
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#define _USE_MATH_DEFINES
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#include <math.h>
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#include "PluginFx.h"
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#include "PluginProcessor.h"
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static float gaintable[199] = {
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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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,
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0.257599, 0.256317, 0.255035, 0.25375
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};
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static inline float saturate(float input) { //clamp without branching
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#define _limit 0.95
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float x1 = fabsf( input + _limit );
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float x2 = fabsf( input - _limit );
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return 0.5 * (x1 - x2);
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}
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static inline float crossfade(float amount, float a, float b) {
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return (1-amount) * a + amount * b;
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}
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void PluginFx::init(int sampleRate) {
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uiCutoff = 1;
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uiReso = 0;
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srate = sampleRate;
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output = 0;
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for(int i=0;i<4;i++)
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state[i] = 0;
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}
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void PluginFx::process(float *work, int sampleSize) {
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// don't apply the LPF if the cutoff is to maximum
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if ( uiCutoff == 1 )
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return;
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// the UI values haved changed
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if ( uiCutoff != pCutoff || uiReso != pReso) {
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// calc cutoff
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// mel scale freq : http://www.speech.kth.se/~giampi/auditoryscales/
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float freqCutoff = 700 * (pow(M_E,(uiCutoff*4000/1127)-1)) + 20;
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float fc = 2 * freqCutoff / srate;
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float x2 = fc*fc;
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float x3 = fc*x2;
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p = -0.69346 * x3 - 0.59515 * x2 + 3.2937 * fc - 1.0072; //cubic fit
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// calc reso
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float ix = p * 99;
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int ixint = floor( ix );
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float ixfrac = ix - ixint;
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Q = uiReso * crossfade( ixfrac, gaintable[ ixint + 99 ], gaintable[ ixint + 100 ] );
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pCutoff = uiCutoff;
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pReso = uiReso;
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}
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for (int i=0; i < sampleSize; i++ ) {
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output = 0.10 * ( work[i] - output ); //negative feedback
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for(int pole=0; pole < 4; pole++) {
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float temp = state[pole];
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output = saturate( output + p * (output - temp));
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state[pole] = output;
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output = saturate( output + temp );
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}
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work[i] = output;
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output *= Q; //scale the feedback
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}
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}
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