Playing a sample at different speeds/frequencies

Core Library Questions

oolong

Playing a sample at different speeds/frequencies

in Core Library Questions • 1 year ago

I've made a sort of interactive fretboard applet, and I'm thinking it could be nice to add some sound to it. Ideally I'd like to play a sample of an actual guitar (or other) string, six times over, each one at a different pitch. I guess I could just make 36 different samples, one for each of the different pitches I've included, but that would be silly. Does Minim include the ability to play clips pitch-shifted, or at least speeded up? It seems like such an obvious thing but I've been staring at the examples and documentation for at least half an hour without seeing anything like a way...

Replies(2)

jbum

Re: Playing a sample at different speeds/frequencies

1 year ago

I agree that it's not clear if this is possible with Minim from reading the docs. It *is* possible with Beads. Here is some sample code that does it.

The SamplePlayer class in beads has a setRate() method. In Beads, most controllable signals (rate, amplitude etc.) are controlled by UGen objects. You can create a Glide() object that passes a constant value to setRate(). A value of 1.0 gets you the original sample rate. A value of 2 gets you twice the sample rate and so on.

To get a pitch that is N half steps above the original pitch, you use pow(2, N / 12.0 )

//Same sample with 6 (guitar) speed changes - Jim Bumgardner
//
// Click on screen to play samples
import beads.*;
AudioContext ac;
Gain g;
void setup()
{
size(500,500);
ac = new AudioContext();
g = new Gain(ac, 1, 0.5);
ac.out.addInput(g);
ac.start();
}
void draw()
{
}
int[] guitarPitches = {0,5,10,15,19,24}; // hlf steps from low e, for each open string
int ctr = 0;
void mouseClicked()
{
int pitchIdx = guitarPitches[ctr];
ctr = (ctr + 1) % guitarPitches.length;
float pitchRatio = pow(2,pitchIdx/12.0);
String sourceFile = dataPath("clean_e_string.wav");
try {
SamplePlayer sp = new SamplePlayer(ac, new Sample(sourceFile));
sp.setRate(new Glide(ac, pitchRatio));
sp.setKillOnEnd(true);
g.addInput(sp);
sp.start();
}
catch (Exception e) {
println("Exception loading sample: " + sourceFile);
e.printStackTrace();
}
}

oolong

Re: Playing a sample at different speeds/frequencies

1 year ago

That's great jbum, just what I needed - thanks so much! Though I still wonder if it is feasible with the core libraries...

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