audio - Set volume of Java Clip

Question

Is there any way to set the respective volume of a Clip in Java?

I have this method:

public static void play(Clip clip) {
    if (Settings.getSettings().isVolumeOn()) {
        FloatControl volume = (FloatControl) clip.getControl(FloatControl.Type.MASTER_GAIN);
        volume.setValue(-1 * Settings.getSettings().getVolume());
        clip.start();
    }
}

The Settings.getSettings().getVolume() returns an Integer in the range of 0 - 100

Volumes:

1. 0 : No Sound
2. 40 : Optimal Sound with headphones
3. 60 : Optimal Sound
4. 100: Full Sound

So essentially this should be like the scale of VLC (but half since VLC is from 0 to 200).

I've found that I can reduce the decibel of the clip by using volume.setValue(-10f);

But I would prefer something of the type volume.setValue(clip.getMaxVolume() * Settings.getSettings().getVolume()/100).

Where clip.getMaxVolume() would return the max volume of the clip.

Answer 1

The MASTER_GAIN FloatControl value is in decibels, meaning it's a logarithmic scale, not a linear one.

While decibels is great for audio professionals, us programmers usually want a nice linear scale where 0.0 is silent, 0.5 is half volume, and 1.0 is full volume; by which I mean normal volume for the sound sample. When playing sound effects, we don't usually amplify sound clips, just attenuate them.

Decibel (dB) to Float Value Calculator explains the maths behind converting decibels to a linear scale, but here is the code:

In Fantom:

using [java] javax.sound.sampled::Clip
using [java] javax.sound.sampled::FloatControl
using [java] javax.sound.sampled::FloatControl$Type as FType

...
private Clip clip

Float volume {
    get {
        gainControl := (FloatControl) clip.getControl(FType.MASTER_GAIN)
        return 10f.pow(gainControl.getValue / 20f)
    }
    set {
        if (it < 0f || it > 1f) throw ArgErr("Invalid volume: $it")
        gainControl := (FloatControl) clip.getControl(FType.MASTER_GAIN)
        gainControl.setValue(20f * it.log10)
    }
}

And converted to Java:

import javax.sound.sampled.Clip;
import javax.sound.sampled.FloatControl;

...

private Clip clip

public float getVolume() {
    FloatControl gainControl = (FloatControl) clip.getControl(FloatControl.Type.MASTER_GAIN);        
    return (float) Math.pow(10f, gainControl.getValue() / 20f);
}

public void setVolume(float volume) {
    if (volume < 0f || volume > 1f)
        throw new IllegalArgumentException("Volume not valid: " + volume);
    FloatControl gainControl = (FloatControl) clip.getControl(FloatControl.Type.MASTER_GAIN);        
    gainControl.setValue(20f * (float) Math.log10(volume));
}

Note there is no need to involve clip.getMaxVolume() or clip.getMinVolume() because using the code above, a volume of 1.0 corresponds to 0 Db (no change) and a volume of 0.1 corresponds to -20 Db (very, very quiet).

If you did want to amplify the sound clip, then there's nothing stopping you from passing in 2.0 to double the normal volume, a-la VLC.

And as a shameless plug, to see what I've used this knowledge for - see Escape the Mainframe - a mini jump game that runs in the Browser and as a desktop Java application. Written in Fantom - have fun!