Range of values for add method for Sound oscillators

paul-reiners · February 14, 2020, 3:25am

What is the range of values for the add method for Sound oscillators?

The documentation says that the method “offset[s] the output of the oscillator by given value”. But what does this mean, exactly?

jeremydouglass · February 17, 2020, 1:05am

Here is the source:

github.com

processing/processing-sound/blob/f8e184db6238a1f15f04b882e34b636141d36ef9/src/processing/sound/SinOsc.java#L104


		super.amp(amp);
	}


	/**
	 * Offset the output of this generator by given value
	 *
	 * @webref sound
	 * @param add
	 *            Offset the output of the oscillator by given value
	 **/
	public void add(float add) {
		super.add(add);
	}


	/**
	 * Move the sound in a stereo panorama.
	 *
	 * @webref sound
	 * @param pos
	 *            the panoramic position of this sound unit from -1.0 (left) to 1.0
	 *            (right).

…which is from Oscillator, which is from SoundObject …

github.com

processing/processing-sound/blob/f8e184db6238a1f15f04b882e34b636141d36ef9/src/processing/sound/SoundObject.java#L42


		this.amplitude.set(this.amp);
	}


	/**
	 * Offset the output of this generator by given value
	 *
	 * @webref sound
	 * @param add
	 *            A value for offsetting the audio signal.
	 **/
	public void add(float add) {
		if (this.circuit.processor == null) {
			Engine.printError("stereo sound sources do not support adding");
		} else {
			this.circuit.processor.add(add);
		}
	}


	/**
	 * Change the amplitude/volume of this sound.
	 *

…and it looks like circuit is a JSynCircuit, and its processor is a JSynProcessor

github.com

processing/processing-sound/blob/master/src/processing/sound/JSynCircuit.java

package processing.sound;

import com.jsyn.ports.UnitOutputPort;
import com.jsyn.unitgen.Circuit;
import com.jsyn.unitgen.TwoInDualOut;
import com.jsyn.unitgen.UnitFilter;
import com.jsyn.unitgen.UnitGenerator;
import com.jsyn.unitgen.UnitSource;

/**
 * Helper class wrapping a source unit generator, add/pan processor and effect into one circuit.
 */
class JSynCircuit extends Circuit implements UnitSource {

	private UnitGenerator source;
	protected JSynProcessor processor;
	protected UnitOutputPort preEffect;
	protected Effect<? extends UnitFilter> effect;
	protected TwoInDualOut output;

This file has been truncated. show original

…and in the JSynProcessor, add is set as a variable, then mixed in directly in generate()

github.com

processing/processing-sound/blob/f8e184db6238a1f15f04b882e34b636141d36ef9/src/processing/sound/JSynProcessor.java#L23-L37


public void generate(int start, int limit) {
    double[] input = this.input.getValues();
    double right = 0.5 + this.pan * 0.5;
    double left = 1 - right;
    double[] outleft = output.getValues(0);
    double[] outright = output.getValues(1);
    for (int i = start; i < limit; i++) {
        outleft[i] = ( input[i] + this.add ) * left;
        outright[i] = ( input[i] + this.add ) * right;
    }
}


public void add(float add) {
	this.add = add;
}

jeremydouglass · February 19, 2020, 12:58am

Also, since add is a float, and outleft and outright values are doubles, you could effectively shift the output values up to Float.MAX_VALUE, or 3.4028235E38 (if I’m understanding correctly) – so I think the bigger question is what values make sense for what are representing and how much you want to shift them.

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Range of values for add method for Sound oscillators

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