interpreter/preprocessor/faust-0.9.47mr3/examples/faust-stk/NLFeks.dsp

   1 declare name "Nonlinear EKS";
   2 declare author "Julius Smith and Romain Michon";
   3 declare version "1.0";
   4 declare license "STK-4.3";
   5 declare copyright "Julius Smith";
   6 declare reference "http://ccrma.stanford.edu/~jos/pasp/vegf.html";
   7 // -> Virtual\_Electric\_Guitars\_Faust.html";
   8
   9 import("music.lib");    // Define SR, delay
  10 import("instrument.lib");
  11 import("effect.lib");   // stereopanner
  12
  13 //==================== GUI SPECIFICATION ================
  14
  15 // standard MIDI voice parameters:
  16 // NOTE: The labels MUST be "freq", "gain", and "gate" for faust2pd
  17 freq = nentry("freq", 440, 20, 7040, 1);  // Hz
  18 gain = nentry("gain", 1, 0, 10, 0.01);    // 0 to 1
  19 gate = button("gate");                    // 0 or 1
  20
  21 // Additional parameters (MIDI "controllers"):
  22
  23 // Pick angle in [0,0.9]:
  24 pickangle = 0.9 * hslider("pick_angle",0,0,0.9,0.1);
  25
  26 // Normalized pick-position in [0,0.5]:
  27 beta = hslider("pick_position [midi: ctrl 0x81]", 0.13, 0.02, 0.5, 0.01);
  28        // MIDI Control 0x81 often "highpass filter frequency"
  29
  30 // String decay time in seconds:
  31 t60 = hslider("decaytime_T60", 4, 0, 10, 0.01);  // -60db decay time (sec)
  32
  33 // Normalized brightness in [0,1]:
  34 B = hslider("brightness [midi:ctrl 0x74]", 0.5, 0, 1, 0.01);// 0-1
  35     // MIDI Controller 0x74 is often "brightness"
  36     // (or VCF lowpass cutoff freq)
  37
  38 // Dynamic level specified as dB level desired at Nyquist limit:
  39 L = hslider("dynamic_level", -10, -60, 0, 1) : db2linear;
  40 // Note: A lively clavier is obtained by tying L to gain (MIDI velocity).
  41
  42 //Nonlinear filter parameters
  43 typeModulation = nentry("v:Nonlinear Filter/typeMod",0,0,4,1);
  44 nonLinearity = hslider("Nonlinearity",0,0,1,0.01) : smooth(0.999);
  45 frequencyMod = hslider("freqMod",220,20,1000,0.1) : smooth(0.999);
  46
  47 //==================== SIGNAL PROCESSING ================
  48
  49 //----------------------- noiseburst -------------------------
  50 // White noise burst (adapted from Faust's karplus.dsp example)
  51 // Requires music.lib (for noise)
  52 noiseburst(gate,P) = noise : *(gate : trigger(P))
  53 with {
  54   diffgtz(x) = (x-x') > 0;
  55   decay(n,x) = x - (x>0)/n;
  56   release(n) = + ~ decay(n);
  57   trigger(n) = diffgtz : release(n) : > (0.0);
  58 };
  59
  60 nlfOrder = 6;
  61 P = SR/freq ; // fundamental period in samples
  62 Pmax = 4096; // maximum P (for delay-line allocation)
  63
  64 ppdel = beta*P; // pick position delay
  65 pickposfilter = ffcombfilter(Pmax,ppdel,-1); // defined in filter.lib
  66
  67 excitation = noiseburst(gate,P) : *(gain); // defined in signal.lib
  68
  69 rho = pow(0.001,1.0/(freq*t60)); // multiplies loop-gain
  70
  71 // Original EKS damping filter:
  72 b1 = 0.5*B; b0 = 1.0-b1; // S and 1-S
  73 dampingfilter1(x) = rho * ((b0 * x) + (b1 * x'));
  74
  75 // Linear phase FIR3 damping filter:
  76 h0 = (1.0 + B)/2; h1 = (1.0 - B)/4;
  77 dampingfilter2(x) = rho * (h0 * x' + h1*(x+x''));
  78
  79 loopfilter = dampingfilter2; // or dampingfilter1
  80
  81 filtered_excitation = excitation : smooth(pickangle)
  82                     : pickposfilter : levelfilter(L,freq); // see filter.lib
  83
  84 //nonlinear allpass filter (nonLinearModulator is declared in instrument.lib)
  85 NLFM =  nonLinearModulator(nonLinearity,1,freq,typeModulation,frequencyMod,nlfOrder);
  86
  87 //declared in instrument.lib
  88 stereo = stereoizer(P);
  89
  90 stringloop = (+ : fdelay4(Pmax, P-2)) ~ (loopfilter : NLFM);
  91
  92 process = filtered_excitation : stringloop : stereo : instrReverb;