title: Webrtc conference call recording using recordrtc
body: <p>I'm building new application using Angular 7 and WebRTC,and I use recordRTC.js to recording (audio&amp;video) my issue is when I record multiple streams only audio of first stream is recorded.</p>
  
  <pre><code>public addStreamToRecorder(stream: MediaStream) 
  {
  
    if (!this.recorder) 
       {
        this.recorder = RecordRTC([stream],{type: "video"});
        this.recorder.startRecording();
       } 
    else 
       {
        this.recorder.getInternalRecorder().addStreams([stream]);
       }
   }
  </code></pre>
  
  <p>after investigation  i found that appendStreams function in reocrdrtc not mix audios</p>