-declare name "Commuted Piano";
-declare description "WaveGuide Commuted Piano";
-declare author "Romain Michon (rmichon@ccrma.stanford.edu)";
-declare copyright "Romain Michon";
-declare version "1.0";
-declare licence "STK-4.3"; // Synthesis Tool Kit 4.3 (MIT style license);
-declare description "A commuted WaveGuide piano.";
-
-import("music.lib");
-import("instrument.lib");
-
-//==================== GUI SPECIFICATION ================
-
-freq = nentry("h:Basic_Parameters/freq [1][unit:Hz] [tooltip:Tone frequency]",440,20,20000,1);
-gain = nentry("h:Basic_Parameters/gain [1][tooltip:Gain (value between 0 and 1)]",1,0,1,0.01);
-gate = button("h:Basic_Parameters/gate [1][tooltip:noteOn = 1, noteOff = 0]");
-
-brightnessFactor = hslider("v:Physical_Parameters/Brightness_Factor
-[2][tooltip:A value between 0 and 1]",0,0,1,0.01);
-detuningFactor = hslider("v:Physical_Parameters/Detuning_Factor
-[2][tooltip:A value between 0 and 1]",0.1,0,1,0.01)*10;
-stiffnessFactor = hslider("v:Physical_Parameters/Stiffness_Factor
-[2][tooltip:A value between 0 and 1]",0.28,0,1,0.01)*3.7;
-hammerHardness = hslider("v:Physical_Parameters/Hammer_Hardness
-[2][tooltip:A value between 0 and 1]",0.1,0,1,0.01)*0.1;
-
-//==================== COMMUTED PIANO PARAMETERS ================
-
-//variables to set keybord splitting zone
-DCB2_TURNOFF_KEYNUM = 92;
-FIRST_HIGH_NOTE = 88;
-PEDAL_ENVELOPE_T60 = 7;
-
-//convert an amplitude in db
-dbinv(x) = pow(10,0.05*x);
-
-//convert a frequency in a midi note number
-freqToNoteNumber = (log-log(440))/log(2)*12+69+0.5 : int;
-freqn = freq : freqToNoteNumber;
-
-//a counter that restart a every note-on
-cntSample = *(gate)+1~_ : -(1);
-
-//==================== PIANO SOUND BOARD ================
-
-//exponential envelope with 3 phases for the pedal excitation
-asympT60pedal(value,T60) = (*(factor) + constant)~_
- with{
- attDur = hammerHardness*float(SR);
- target = value*((cntSample < attDur) & (gate > 0));
- factorAtt = exp (-1/(attDur));
- factorG = exp(-1/(2*float(SR)));
- factorT60 = exp(-7/(T60*float(SR)));
- factor = factorAtt*gate*(cntSample < attDur) + (cntSample >= attDur)*gate*factorG + ((gate-1)*-1)*factorT60;
- constant = (1 - factor)*target;
- };
-
-//the sound of the piano sound board is generated by noise generator whose output gain is shaped by
-//an exponential envelope
-soundBoard = dryTapAmp*noise + pedalEnv*noise : *(0.5)
- with{
- //the values of the envelope cut-off time are stored in an external C++ function
- dryTapAmpT60 = ffunction(float getValueDryTapAmpT60(float), <piano.h>,"");
- sustainPedalLevel = ffunction(float getValueSustainPedalLevel(float), <piano.h>,"");
-
- pedalEnvCutOffTime = 1.4;
- noteCutOffTime = freqn : dryTapAmpT60*gain;
- pedalEnvValue = freqn : sustainPedalLevel*0.2;
- noteEnvValue = 0.15;
- dryTapAmp = asympT60(noteEnvValue,0,noteCutOffTime,gate);
- pedalEnv = asympT60pedal(pedalEnvValue,pedalEnvCutOffTime);
- };
-
-//==================== HAMMER MODELING ================
-
-//To model the exitation hammer, we filter the sound from the soundboard with a serie of 4 one pole filters
-//connected in serie
-
-//onePole is declared in instrument.lib
-calcHammer = onePole((1-hammerPole)*hammerGain,-hammerPole)
- with{
- //filter gains and coefficients are stored in external C++ files
- loudPole = ffunction(float getValueLoudPole(float), <piano.h>,"");
- softPole = ffunction(float getValuePoleValue(float), <piano.h>,"");
- loudGain = ffunction(float getValueLoudGain(float), <piano.h>,"");
- softGain = ffunction(float getValueSoftGain(float), <piano.h>,"");
-
- loudPoleValue = loudPole(freqn) + (brightnessFactor*-0.25) + 0.02;
- softPoleValue = softPole(freqn);
- normalizedVelocityValue = 1;
- loudGainValue = loudGain(freqn);
- softGainValue = softGain(freqn);
- overallGain = 1;
- hammerPole = softPoleValue + (loudPoleValue - softPoleValue)*normalizedVelocityValue;
- hammerGain = overallGain*(softGainValue + (loudGainValue - softGainValue)*normalizedVelocityValue);
- };
-
-hammer = seq(i,4,calcHammer);
-
-//==================== DC BLOCKERS ================
-
-//the values for the dcblockers a1 are stored in an external C++ file
-DCBa1 = ffunction(float getValueDCBa1(float), <piano.h>,"");
-dCBa1Value = freqn : DCBa1;
-dCBb0Value = 1 - dCBa1Value;
-
-dcBlock1 = poleZero((dCBb0Value*0.5),(dCBb0Value*-0.5),dCBa1Value);
-
-dcBlock2a = oneZero1(0.5,-0.5);
-
-dcBlock2b = onePole(dCBb0Value,dCBa1Value);
-
-//==================== HIGH TUNING CALCULATION ================
-
-//high tones are not generated with the waveguide technique but with a serie of biquad filters
-
-r1_1 = ffunction(float getValuer1_1db(float), <piano.h>,"");
-r1_2 = ffunction(float getValuer1_2db(float), <piano.h>,"");
-r2 = ffunction(float getValuer2db(float), <piano.h>,"");
-r3 = ffunction(float getValuer3db(float), <piano.h>,"");
-e = ffunction(float getValueSecondStageAmpRatio(float), <piano.h>,"");
-second_partial_factor = ffunction(float getValueSecondPartialFactor(float), <piano.h>,"");
-third_partial_factor = ffunction(float getValueThirdPartialFactor(float), <piano.h>,"");
-bq4_gEarBalled = ffunction(float getValueBq4_gEarBalled(float), <piano.h>,"");
-
-r1_1Value = r1_1(freqn)/SR : dbinv;
-r1_2Value = r1_2(freqn)/SR : dbinv;
-r2Value = r2(freqn)/SR : dbinv;
-r3Value = r3(freqn)/SR : dbinv;
-eValue = e(freqn) : dbinv;
-second_partial_factorValue = second_partial_factor(freqn);
-third_partial_factorValue = third_partial_factor(freqn);
-
-//set biquad gains and coeffs
-gainHighBq(0) = bq4_gEarBalled(freqn)/0.5;
-gainHighBq(1) = bq4_gEarBalled(freqn)/0.5;
-gainHighBq(2) = 1;
-gainHighBq(3) = 1;
-
-b0HighBq(0) = 1;
-b0HighBq(1) = 1;
-b0HighBq(2) = 1;
-b0HighBq(3) = 1;
-
-b1HighBq(0) = 0;
-b1HighBq(1) = 0;
-b1HighBq(2) = -2*(eValue*r1_1Value+(1-eValue)*r1_2Value)*cos(2*PI*freq/SR);
-b1HighBq(3) = 0;
-
-b2HighBq(0) = 0;
-b2HighBq(1) = 0;
-b2HighBq(2) = eValue*r1_1Value*r1_1Value+(1-eValue)*r1_2Value*r1_2Value;
-b2HighBq(3) = 0;
-
-a1HighBq(0) = -2*r3Value*cos(2*PI*freq*third_partial_factorValue/SR);
-a1HighBq(1) = -2*r2Value*cos(2*PI*freq*second_partial_factorValue/SR);
-a1HighBq(2) = -2*r1_1Value*cos(2*PI*freq/SR);
-a1HighBq(3) = -2*r1_2Value*cos(2*PI*freq/SR);
-
-a2HighBq(0) = r3Value*r3Value;
-a2HighBq(1) = r2Value*r2Value;
-a2HighBq(2) = r1_1Value*r1_1Value;
-a2HighBq(3) = r1_2Value*r1_2Value;
-
-highBqs = seq(i,4,*(gainHighBq(i)) : TF2(b0HighBq(i),b1HighBq(i),b2HighBq(i),a1HighBq(i),a2HighBq(i)));
-
-hiPass = oneZero1(b0,b1)
- with{
- b0 = -0.5;
- b1 = -0.5;
- };
-
-//==================== STRIKE POSITION COMB FILTER EQ ================
-
-eq = _*filterGain : TF2(b0,b1,b2,a1,a2)
- with{
- strikePosition = ffunction(float getValueStrikePosition(float), <piano.h>,"");
- bandwidthFactors = ffunction(float getValueEQBandWidthFactor(float), <piano.h>,"");
- eq_gain = ffunction(float getValueEQGain(float), <piano.h>,"");
- eq_tuning = freq/strikePosition(freqn);
- eq_bandwidth = bandwidthFactors(freqn)*freq;
- filterGain = eq_gain(freqn);
- a2 = (eq_bandwidth / SR) * (eq_bandwidth / SR);
- a1 = -2*(eq_bandwidth / SR)*cos(2*PI*eq_tuning/SR);
- b0 = 0.5 - 0.5 * a2;
- b1 = 0;
- b2 = -b0;
- };
-
-//==================== PIANO COUPLED STRINGS ================
-
-//values for the couple strings are stored in externals C++ functions
-singleStringDecRate = ffunction(float getValueSingleStringDecayRate(float), <piano.h>,"");
-singleStringZero = ffunction(float getValueSingleStringZero(float), <piano.h>,"");
-singleStringPole = ffunction(float getValueSingleStringPole(float), <piano.h>,"");
-stiffnessCoefficient = ffunction(float getValueStiffnessCoefficient(float), <piano.h>,"");
-
-//coupling filter parameters
-g = pow(10,((singleStringDecRate(freqn)/freq)/20)); //attenuation per period
-b = singleStringZero(freqn);
-a = singleStringPole(freqn);
-tempd = 3*(1-b)-g*(1-a);
-b0Coupling = 2*(g*(1-a)-(1-b))/tempd;
-b1Coupling = 2*(a*(1-b)-g*(1-a)*b)/tempd;
-a1Coupling = (g*(1-a)*b - 3*a*(1-b))/tempd;
-
-//string stiffness
-stiffness = stiffnessFactor*stiffnessCoefficient(freqn);
-
-stiffnessAP = poleZero(b0s,b1s,a1s)
- with{
- b0s = stiffness;
- b1s = 1;
- a1s = stiffness;
- };
-
-delayG(frequency,stiffnessCoefficient) = fdelay(4096,delayLength)
- with{
- allPassPhase(a1,WT) = atan2((a1*a1-1.0)*sin(WT),(2.0*a1+(a1*a1+1.0)*cos(WT)));
- poleZeroPhase(b0,b1,a1,WT) = atan2(-b1*sin(WT)*(1 + a1*cos(WT)) + a1*sin(WT)*(b0 + b1*cos(WT)),
- (b0 + b1*cos(WT))*(1 + a1*cos(WT)) + b1*sin(WT)*a1*sin(WT));
- wT = frequency*2*PI/SR;
- delayLength = (2*PI + 3*allPassPhase(stiffnessCoefficient, wT) +
- poleZeroPhase((1+2*b0Coupling),
- a1Coupling + 2*b1Coupling, a1Coupling, wT)) / wT;
- };
-
-coupledStrings = (parallelStrings <: (_,(_+_ <: _,_),_ : _,_,(_ : couplingFilter),_ : adder))~(_,_) : !,!,_
- with{
- releaseLoopGain = ffunction(float getValueReleaseLoopGain(float), <piano.h>,"");
- hz = ffunction(float getValueDetuningHz(float), <piano.h>,"");
- coupledStringLoopGain = gate*0.9996 + ((gate-1)*-1)*releaseLoopGain(freqn)*0.9 : smooth(0.999);
- couplingFilter = poleZero(b0Coupling,b1Coupling,a1Coupling);
- hzValue = hz(freqn);
- freq1 = freq + 0.5*hzValue*detuningFactor;
- freq2 = freq - 0.5*hzValue*detuningFactor;
- delay1 = delayG(freq1,stiffness);
- delay2 = delayG(freq2,stiffness);
- parallelStrings(x,y) = _ <: (+(x)*coupledStringLoopGain : seq(i,3,stiffnessAP) : delay1),
- (_+y*coupledStringLoopGain : seq(i,3,stiffnessAP) : delay2);
- adder(w,x,y,z) = (y <: +(w),+(z)),x ;
- };
-
-//stereoizer is declared in instrument.lib and implement a stereo spacialisation in function of
-//the frequency period in number of samples
-stereo = stereoizer(SR/freq);
-
-//==================== PROCESSING ================
-
-conditionLowNote = freqn < FIRST_HIGH_NOTE;
-conditionHighNote = freqn >= FIRST_HIGH_NOTE;
-
-process = soundBoard <: (*(conditionLowNote)*6 : hammer : dcBlock1 : coupledStrings <: +(eq)),
-(*(conditionHighNote) : hiPass : dcBlock1 : hammer : dcBlock2a : highBqs : dcBlock2b) :> + : *(12) :
-stereo : instrReverb;