Changing volume in Java when using JLayer

Question

I'm using JLayer to play an inputstream of mp3 data from the internet. How do i change the volume of the output?

I'm using this code to play it:

URL u = new URL(s);
URLConnection conn = u.openConnection();  
conn.setConnectTimeout(Searcher.timeoutms);  
conn.setReadTimeout(Searcher.timeoutms);

bitstream = new Bitstream(conn.getInputStream()/*new FileInputStream(quick_file)*/);
System.out.println(bitstream);
decoder = new Decoder();
decoder.setEqualizer(equalizer);
audio = FactoryRegistry.systemRegistry().createAudioDevice();
audio.open(decoder);
for(int i = quick_positions[0]; i > 0; i--){
    Header h = bitstream.readFrame();
    if (h == null){
        return;
    }
bitstream.closeFrame();

Answer 1

You may consider this an unacceptable hack, but it worked in an MP3 player I wrote. It requires a small code addition to one of the JLayer classes.

Add the following method to javazoom.jl.player.JavaSoundAudioDevice.

public void setLineGain(float gain)
{
    if (source != null)
    {
        FloatControl volControl = (FloatControl) source.getControl(FloatControl.Type.MASTER_GAIN);
        float newGain = Math.min(Math.max(gain, volControl.getMinimum()), volControl.getMaximum());

        volControl.setValue(newGain);
    }
}

This new method then allows you to change the volume with code like this.

if (audio instanceof JavaSoundAudioDevice)
{
    JavaSoundAudioDevice jsAudio = (JavaSoundAudioDevice) audio;
    jsAudio.setLineGain(yourGainGoesHere);
}

Answer 2

Another (non-JLayer) way to adjust the PC's speaker volume is to use classes in the javax.sound.sampled package provided by Sun/Oracle.

On my machine, SPEAKER was the only output target supported.

import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.FloatControl;
import javax.sound.sampled.Line.Info;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.Port;

public class SoundVolumeDemo 
{

    public static void main(String[] args) 
{        
    Info source = Port.Info.SPEAKER;
    //        source = Port.Info.LINE_OUT;
    //        source = Port.Info.HEADPHONE;

        if (AudioSystem.isLineSupported(source)) 
        {
            try 
            {
                Port outline = (Port) AudioSystem.getLine(source);
                outline.open();                
                FloatControl volumeControl = (FloatControl) outline.getControl(FloatControl.Type.VOLUME);                
                System.out.println("       volume: " + volumeControl.getValue() );
                float v = 0.33F;
                volumeControl.setValue(v);
                System.out.println("   new volume: " + volumeControl.getValue() );
                v = 0.73F;
                volumeControl.setValue(v); 
                System.out.println("newest volume: " + volumeControl.getValue() );
            } 
            catch (LineUnavailableException ex) 
            {
                System.err.println("source not supported");
                ex.printStackTrace();
            }            
        }
    } 

 }

This is how I am achieving volume control in this app:

http://onebeartoe.com/media-players/randomjuke/filesystem/java-web-start/swing/index.jsp

Please note that I have only had experience with it working on MS Windows OS machines.