Java: Master Gain not supported exception

Question

In linux this code doesn't work: I added two lines

// Added two lines.
DataLine.Info info = new DataLine.Info( SourceDataLine.class, audioFormat );
SourceDataLine dataLine = (SourceDataLine) AudioSystem.getLine( info );
// Adjust the volume on the output line.
if( dataLine.isControlSupported( FloatControl.Type.MASTER_GAIN)) {
    // If inside this if, the Master_Gain must be supported. Yes?
    FloatControl volume = (FloatControl) dataLine.getControl(FloatControl.Type.MASTER_GAIN);
    // This line throws an exception. "Master_Gain not supported"
    volume.setValue( 100.0F );
}

Is this normal? What do I have to do to solve this?
In windows does it work.

Thanks, Martijn.

Answer 1

Could you try to open() the line before trying to use controls on it. Something like this:

// Added two lines.
DataLine.Info info = new DataLine.Info( SourceDataLine.class, audioFormat );
SourceDataLine dataLine = (SourceDataLine) AudioSystem.getLine( info );
dataLine.open();
// Adjust the volume on the output line.
if( dataLine.isControlSupported( FloatControl.Type.MASTER_GAIN)) {
    // If inside this if, the Master_Gain must be supported. Yes?
    FloatControl volume = (FloatControl) dataLine.getControl(FloatControl.Type.MASTER_GAIN);
    // This line throws an exception. "Master_Gain not supported"
    volume.setValue( 100.0F );
}

Answer 2

It looks like it differs depending on the JRE version.

I'm having a similar problem and when I check dataLine.getControls(), I get a "MASTER_GAIN" Control on Oracle JDK 1.7 and a "Volume" Control on OpenJDK 1.6. And what makes it worse ... the "Volume" has a linear value from 0...65536 while the MASTER_GAIN seems to have a decibel setting.

So much for code once, run everywhere :-(