title: How to get current uploading speed when live stream with RTMP
body: <p>I want to create an application to live stream with RTMP.
  And I use <strong>NetStream.publish</strong> to live stream.</p>
  
  <p>When I set <strong>NetStream.bufferTime=0 (default value)</strong>, I can create a Timer to get <strong>NetStream.info.currentBytesPerSecond</strong> as uploading speed.</p>
  
  <p>But if I set  <strong>NetStream.bufferTime= 1(Some value larger then 0)</strong> ,  <strong>NetStream.info.currentBytesPerSecond</strong> becomes 0 and never change~</p>
  
  <p>Can someone help me? Thanks </p>