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