title: WebRTC remove track from stream
body: <p>I'm programming using PeerJS and, because PeerJS is already very outdated, I'm testing everything on Firefox version 38. I know it is not the best to do, but I don't have time for more. So, I'm trying to do the following: </p>
  
  <p>Peer1 transmits audio and video to Peer2. </p>
  
  <p>Peer2 wants to transmit to Peer3 the video that receives from Peer1 but not the audio. Peer2 wants to send it's own audio.</p>
  
  <p>Basically, Peer3 will receive the video from Peer1 (with Peer2 relaying it) and audio from Peer2, but it will arrive to him all together, like if it was a normal WebRTC call.</p>
  
  <p>I do this like this: </p>
  
  <pre><code>var mixStream = remoteStream;
  
  var audioMixStream = mixStream.getAudioTracks();
  
  mixStream = mixStream.removeStream(audioMixStream);
  
  var mixAudioStream = localStream;
  
  var audioMixAudioStream = mixAudioStream.getAudioTracks();
  
  mixStream.addTrack(audioMixAudioStream);
  
  //Answer the call automatically instead of prompting user.
  call.answer(window.audioMixAudioStream);
  </code></pre>
  
  <p>But I'm getting an error on removeStream. Maybe I will get more errors after that one, but now I'm stuck on this one.</p>
  
  <p>Can someone please tell what I should use instead of removeStream?</p>
  
  <p>P.S.: I already used removeTrack too and got an error too.</p>