DefaultSoundEffect.java 文件源码

/**
 * Sets the volume.
 *
 * @param vol the volume
 */
private void setVolume(final int vol) {

    int volume = vol;
    if (volume < 0) {
        volume = MAX_VOLUME;
    }
    float gainDb = 0.0f;
    final FloatControl gain = (FloatControl) clip.getControl(FloatControl.Type.MASTER_GAIN);

    if (volume == 0) {
        gainDb = gain.getMinimum();

    } else if (volume < MAX_VOLUME) {

  // The volume algorithm is subtractive: The implementation assumes that
        // the sound is already at maximum volume, so we avoid distortion by
        // making the amplitude values
        // The scaling factor for the volume would be 20 normally, but
        // it seems that 13 is better
        gainDb = (float) (Math.log10(MAX_VOLUME - volume) * 13.0);
    }
    gain.setValue(-gainDb);
}