title: Passing duration when streaming mp3 from server to html5 audio
body: <p>I have a node.js server converting and streaming mp3's on the fly.
  I am using an HTML5 audio tag to consume this stream, and the issue I'm having is the audio element doesn't know the duration of the mp3 until it has finished playing the whole thing (obviously). 
  Is there any way, since my server knows the duration of the mp3 before sending it, that I can include the duration in the header of the response from the server or something, so the client consuming it knows the duration?</p>
  
  <p>Thanks</p>