title: Can HTML5 track element be used for *live* subtitles?
body: <p>I am planning to build a system to broadcast public events (trials, meetings, conferences).</p>
  
  <p>A key request will be the insertion of <em>live</em> subtitles to the A/V stream.</p>
  
  <p>The subtitles will be "live" since they will be produced by an operator while the event will happen.</p>
  
  <p>I suppose the HTML5 "track" element is not yet implemented by any of the major browsers, but: can I expect to eventually use it for <em>live</em> subtitles? Will I be able to inject the subtitle to the page while the stream is playing?</p>