Minim AudioInput NullPointerException

Processing Libraries
1

Just got a new MacBook Pro and for some reason Minim AudioInput has trouble connecting to the Default LineIn. Was wondering if anyone else is experiencing this problem. If you would like to try, I am just running the default MonitorInput sketch in the Examples of Minim. Pasted the code below.

/**
  * This sketch demonstrates how to monitor the currently active audio input 
  * of the computer using an AudioInput. What you will actually 
  * be monitoring depends on the current settings of the machine the sketch is running on. 
  * Typically, you will be monitoring the built-in microphone, but if running on a desktop
  * it's feasible that the user may have the actual audio output of the computer 
  * as the active audio input, or something else entirely.
  * <p>
  * Press 'm' to toggle monitoring on and off.
  * <p>
  * When you run your sketch as an applet you will need to sign it in order to get an input.
  * <p>
  * For more information about Minim and additional features, 
  * visit http://code.compartmental.net/minim/ 
  */

import ddf.minim.*;

Minim minim;
AudioInput in;

void setup()
{
  size(512, 200, P3D);

  minim = new Minim(this);
  
  // use the getLineIn method of the Minim object to get an AudioInput
  in = minim.getLineIn();
}

void draw()
{
  background(0);
  stroke(255);
  
  // draw the waveforms so we can see what we are monitoring
  for(int i = 0; i < in.bufferSize() - 1; i++)
  {
    line( i, 50 + in.left.get(i)*50, i+1, 50 + in.left.get(i+1)*50 );
    line( i, 150 + in.right.get(i)*50, i+1, 150 + in.right.get(i+1)*50 );
  }
  
  String monitoringState = in.isMonitoring() ? "enabled" : "disabled";
  text( "Input monitoring is currently " + monitoringState + ".", 5, 15 );
}

void keyPressed()
{
  if ( key == 'm' || key == 'M' )
  {
    if ( in.isMonitoring() )
    {
      in.disableMonitoring();
    }
    else
    {
      in.enableMonitoring();
    }
  }
}
2

Finally tracked down the answer on this one. This example used to work out of the box, but it seems on new MacBook pros you have to add the line:

in = minim.getLineIn(Minim.MONO);

After running it with this line works perfectly. Back to working with audio!

Full sketch:

/**
  * This sketch demonstrates how to monitor the currently active audio input 
  * of the computer using an AudioInput. What you will actually 
  * be monitoring depends on the current settings of the machine the sketch is running on. 
  * Typically, you will be monitoring the built-in microphone, but if running on a desktop
  * it's feasible that the user may have the actual audio output of the computer 
  * as the active audio input, or something else entirely.
  * <p>
  * Press 'm' to toggle monitoring on and off.
  * <p>
  * When you run your sketch as an applet you will need to sign it in order to get an input.
  * <p>
  * For more information about Minim and additional features, 
  * visit http://code.compartmental.net/minim/ 
  */

import ddf.minim.*;

Minim minim;
AudioInput in;

void setup()
{
  size(512, 200, P3D);

  minim = new Minim(this);
  
  // use the getLineIn method of the Minim object to get an AudioInput
  in = minim.getLineIn();
}

void draw()
{
  background(0);
  stroke(255);
  
  // draw the waveforms so we can see what we are monitoring
  for(int i = 0; i < in.bufferSize() - 1; i++)
  {
    line( i, 50 + in.left.get(i)*50, i+1, 50 + in.left.get(i+1)*50 );
    line( i, 150 + in.right.get(i)*50, i+1, 150 + in.right.get(i+1)*50 );
  }
  
  String monitoringState = in.isMonitoring() ? "enabled" : "disabled";
  text( "Input monitoring is currently " + monitoringState + ".", 5, 15 );
}

void keyPressed()
{
  if ( key == 'm' || key == 'M' )
  {
    if ( in.isMonitoring() )
    {
      in.disableMonitoring();
    }
    else
    {
      in.enableMonitoring();
    }
  }
}
1 Like
3

Thanks! I had the same issue.

1 Like