EventID and restarting publishing points using Expression Encoder 4 SP1

In the service pack for Expression Encoder 4, we added the ability to specify an EventID for live smooth streaming broadcasts.  This feature is extremely useful to prevent down-level cache pollution (where you can here/see stale cached fragments when reusing publishing points).   You can use any string that contains URL safe characters or clicking the Generate button will put the current date/time as a string.


Another benefit of the EventID field is that it will allow you to restart your
publishing point from a Stopped state.  When the Encoder stops broadcasting to an IIS Smooth Streaming publish point, we send an empty 'mfra' box which informs the publish point to switch to a Stopped state.  This allows for DVR playback to be available to the users immediately after the broadcast ends.  The Encoder does not allow you to connect to a publishing point that is in use and to check this, we check to see if there is a manifest associated with the pub point.  A manifest will exist if the publishing point is in a Started or Stopped state so by default we block restarting the publish point.  To work around this, if you specify a different EventID for each broadcast (including the first one, null doesn't count)  to the publishing point that contains the tag:   <meta name="restartOnEncoderReconnect" content="true"
/> :  We will ignore the manifest check and restart the publishing point.  Here are the steps:

  1. Install Expression Encoder 4 SP1
  2. Install IIS Media 4.0 on your server
  3. Create a Live Smooth Streaming publishing point on the server.
  4. Using Explorer, navigate to the location of the publishing point.
  5. Open the ISML file in a text editor and add the following between the <head> tags:  <meta name="restartOnEncoderReconnect" content="true"
  6. Now set up your broadcast in the Encoder and point to the publishing point.
  7. Before clicking Start, specify an EventID on the Output panel.
  8. Now if you want to reuse the same publishing point for another broadcast,  just specify a different EventID and click Start