title: Video buffering in IE/Edge using Media Source Extensions
body: <p>We are trying to use MSE (Media Source Extensions) to show real time video on a website. We are sending frames over websocket and trying our hardest to keep latency down.
  Our current prototype is streaming very well in IE, Edge, Chrome, Safari etc. 
  The issue we have is that IE and Edge insists on buffering around 3-5 seconds before starting to play the video. This is not acceptable in our use case (live video from security cameras).
  We are wondering if there is some property or similar (we have tried setting preload=none, with no success) which removes this buffering?
  All other browsers happily starts playing when the first frame is added to the sourceBuffer, and we want the same behavior from IE/Edge.
  Is there any other workaround you can suggest for us?</p>
  
  <p>The frames are in the <a href="https://w3c.github.io/media-source/isobmff-byte-stream-format.html" rel="nofollow noreferrer">ISO BMFF format</a></p>
  
  <p>Here is a <a href="https://oskbor.github.io/ie_5s_buffer.html" rel="nofollow noreferrer">reproducing example</a> I have created that measures the time from the first frame is appended to the video starts playing.It uses an interval to spoof data arriving over a websocket.</p>
  
  <p>Results:</p>
  
  <pre><code>Browser       Delay(ms)
  -----------------------
  Chrome:           ~300
  Safari @ Mac:       ~7
  Chrome @ Android:  ~30
  IE11 @ Win10:    ~3200
  Edge:            ~3200
  </code></pre>
  
  <p><a href="https://oskbor.github.io/ie_5s.mp4" rel="nofollow noreferrer">Here</a> is the mp4 file, if you want to examine it.</p>