title: How to set volumes in WebRTC?
body: <p>I want to know how to set the volume in WebRTC.</p>
  
  <p>I'm drawing audio like this:</p>
  
  <pre><code>audio = document.createElement('audio');
  audio.controls = true;
  audio.autoplay = true;
  audio.src = window.URL.createObjectURL(stream);
  div.appendChild(audio);
  </code></pre>
  
  <p>I want to make my custom Audio UI. So, I will use HTML's slide bar.</p>
  
  <pre><code>&lt;input type="range"&gt;
  </code></pre>
  
  <p>But, I don't know set volumes in WebRTC stream. How can I set it?</p>