polyrythm impulse to wave pair example

click.ck

class Voice
{
    1.0 => static float multiplier;
    1.0 => static float spread;
    float freq;
    float pan;
    Impulse imp;
    Pan2 p;

    fun static Voice Voice(float freq, float pan)
    {
        Voice v;
        freq => v.freq;
        pan => v.pan;
        spork ~ v.cycle();
        return v;
    }

    fun static void increaseSpread()
    {
        Math.min(1.0, spread + 0.05) => spread;
    }

    fun static void decreaseSpread()
    {
        Math.max(0.0, spread - 0.05) => spread;
    }

    fun void cycle()
    {
        float targetFreq;
        dur targetBeat;
        imp => p => dac;
        while(true)
        {
            freq * multiplier => targetFreq;
            1::second / targetFreq => targetBeat;
            targetBeat - (now % targetBeat) => now;
            pan * spread => p.pan;
            1.0 => imp.next;
        }
    }
}

fun void keyboardListener()
{
    Hid hi;
    HidMsg msg;
    0 => int device; // the device number for the keyboard.
                     // It's generally either 0 or 1.  For me it's 0.
    if(!hi.openKeyboard(device)) me.exit();
    <<< "keyboard '" + hi.name() + "' ready", "" >>>;
    while(true)
    {
        hi => now;
        while(hi.recv(msg))
        {
            if(msg.isButtonDown())
            {
                if(msg.ascii == 68) // d
                    2 *=> Voice.multiplier;
                else if(msg.ascii == 72) // h
                    2 /=> Voice.multiplier;
                else if(msg.ascii == 73) // i
                    Voice.decreaseSpread();
                else if(msg.ascii == 79) // o
                    Voice.increaseSpread();
            }
        }
    }
}

Voice.Voice(3.0, -1);
Voice.Voice(2.0, 1);
spork ~ keyboardListener();
while(true) { 100::ms => now; }

this is ChucK, a language for audio synthesis programming. It's quite fun!

http://chuck.cs.princeton.edu/

a user on the ChucK mailing list asked about creating a script that would demonstrate that a waveform, slowed down repeatedly, is analagous to a beat on another timescale. This example illustrates this principle by allowing the user to alter the speed that a pair of clicking noises is generated until it's fast enough to become a pair of tones.

Okey, thanks! I'm no music guy, but maybe I'll try it out, just to see how it work.

It has a really excellent concurrency model, and it's highly accurate in generating time-based events. So if you need to run a number of highly accurate, simultaneous timers for some reason, it's useful. You could, for example, run a timer in a ChucK process and have it generate OSC messages that are consumed by another process and interpreted, which is how people make visualizations, e.g. http://vimeo.com/17397162