Need help getting control of my computer's main output Speaker

Question

At the moment I am trying to use a JSlider in Java to control the master volume of my PC. So far I have been able to locate my PC's main speaker's port. However, I do not know how to successfully call it and run a method like getValue() or setValue().

I have used the following code to search my PC for all of it's audio devices:

Mixer.Info [] mixers = AudioSystem.getMixerInfo();  
    System.out.println("There are " + mixers.length + " mixer info objects");  
    for (Mixer.Info mixerInfo : mixers)  
    {  
        System.out.println("mixer name: " + mixerInfo.getName());  
        Mixer mixer = AudioSystem.getMixer(mixerInfo);  
        Line.Info [] lineInfos = mixer.getTargetLineInfo(); // target, not source  
        for (Line.Info lineInfo : lineInfos)  
        {  
            System.out.println("  Line.Info: " + lineInfo);  
            Line line = null;  
            boolean opened = true;  
            try  
            {  
                line = mixer.getLine(lineInfo);  
                opened = line.isOpen() || line instanceof Clip;  
                if (!opened)  
                {  
                    line.open();  
                }  
                FloatControl volCtrl = (FloatControl)line.getControl(FloatControl.Type.VOLUME);  
                System.out.println("    volCtrl.getValue() = " + volCtrl.getValue());  
            }  
            catch (LineUnavailableException e)  
            {  
                e.printStackTrace();  
        }  
            catch (IllegalArgumentException iaEx)  
            {  
                System.out.println("    " + iaEx);  
            }  
            finally  
            {  
                if (line != null && !opened)  
                {  
                    line.close();  
                }  
            }  
        }  
    }  

How do I get control of my speakers line and alter the value?

I have used this website for help so far.

---

UPDATE

Okay so I think I've come a little bit closer. Under my test GUI program I'm trying to use the Java tutorial's code under "Getting a Line that Has the Desired Controls"(the link you gave me). I pasted it into my program under my JSlider's Change Listener.

This is what it looks like:

Port SPEAKER;
        FloatControl volCtrl;
        try {
          Mixer mixer = AudioSystem.getMixer(null);
          SPEAKER = (Port)mixer.getLine(Port.Info.SPEAKER);
          SPEAKER.open();
          volCtrl = (FloatControl) SPEAKER.getControl(

            FloatControl.Type.VOLUME);

        } catch (Exception e) {
        System.out.println("Failed trying to find LINE_IN"
            + " VOLUME control: exception = " + e);
        }

Whenever I move the slider it prints out the error Exception message "Failed trying to find...". Why isn't it letting me obtain the volCtrl on my main output speakers? How can I fix this code to get control of my SPEAKER?

Answer 1

Great find at JavaRanch! I've gotten a lot of valuable help there.

Once you locate your lines, this tutorial shows how to make a Control: http://docs.oracle.com/javase/tutorial/sound/controls.html

But sometimes the high and low vals are unexpected. I found one line that ranged from -80 to +6 (it was set to mimic a VU meter's decibel range). Thus, you may have to do some numerical conversions from the JSlider output to get a reasonable matching Control value, especially if the Control is exponential.