title: Controlling Volume Mixer
body: <p>I want to control other application volume(firefox).</p>
  
  <p>i can do it with <code>Volume Mixer</code></p>
  
  <p><img src="https://i.stack.imgur.com/QzTN5.jpg" alt="enter image description here"></p>
  
  <p>What is the libraries of the <code>Volume Mixer</code>?</p>