1
2declare name "karplus -- Karplus-Strong string synth";
3declare author "Yann Orlarey";
4declare version "1.0";
5
6import("music.lib");
7
8// control variables
9
10// master volume and pan
11vol	= hslider("vol", -10, -96, 96, 0.1);	// dB
12pan	= hslider("pan", 0, -1, 1, 0.01);	// %
13
14// excitator and resonator parameters
15size	= hslider("samples", 512, 1, 1024, 1);	// #samples
16dtime	= hslider("decay time", 4, 0, 10, 0.01);// -60db decay time
17
18// voice parameters
19freq	= nentry("freq", 440, 20, 20000, 1);	// Hz
20gain	= nentry("gain", 1, 0, 10, 0.01);	// %
21gate	= button("gate");			// 0/1
22bend	= hslider("pitch bend", 0, -2, 2, 0.01);// semitones
23
24/* The excitator: */
25
26upfront(x) 	= (x-x') > 0.0;
27decay(n,x)	= x - (x>0)/n;
28release(n)	= + ~ decay(n);
29trigger(n) 	= upfront : release(n) : >(0.0) : +(leak);
30leak		= 1.0/65536.0; // avoid denormals on Pentium
31excitator	= trigger(size);
32
33/* The resonator: */
34
35average(x)	= (x+x')/2;
36att(d,t)	= 1-1/pow(db2linear(60), d/(SR*t));
37comb(d,a)	= (+ : fdelay(4096, d-1.5)) ~ (average : *(1.0-a));
38resonator(d)	= comb(d,att(d,dtime));
39
40/* DC blocker (see http://ccrma.stanford.edu/~jos/filters/DC_Blocker.html): */
41
42dcblocker(x)	= (x-x') : (+ ~ *(0.995));
43
44/* Karplus-Strong string synthesizer: */
45
46process	= vgroup("1-excitator", noise*gain : *(gate : excitator))
47	: vgroup("2-resonator", resonator(SR/(freq*pow(2,bend/12))))
48	: dcblocker
49        : vgroup("3-master", *(db2linear(vol)) : panner((pan+1)/2));
50