Cablecast VOD file processing time

Applies to

• Cablecast 5.2.0+

Answer

The process of creating a Video On Demand (VOD) file consists of several steps that need to be performed in order.  Here is a rundown of what each step does, and how long it should take:

1. Preparing Source Files
   Performed on SX Video Server
   
   The first step of the Cablecast VOD process is to ensure that the file is ready to be handled by the Cablecast VOD server.  The Cablecast VOD server is only capable of transcoding MPEG-2 files into h.264 files.  Because of this, the first step of preparing a VOD will often be an additional transcoding step.  Our example file is a DVCPro file, so it will need to be transcoded to MPEG-2 before the process can continue.  In order to maintain the performance of on-air playback, this transcoding is done at a low priority.  If the source file is MPEG-2, this step will be skipped and the log will indicate Preparing Source Files - Not Required.
   
   Time: About 60 minutes
   
   
2. Transferring
   Performed on the SX Video Server and the Cablecast VOD Server
   
   The next step is to transfer the file to the Cablecast VOD Server for continued processing.  The file is transferred over an FTP connection using custom ports.  The Cablecast VOD Server starts an FTP server, and the SX Video Server initiates the connection.
   
   Time: About three minutes
   
   
3. Transcoding
   Performed on the Cablecast VOD Server
   
   Now that the Cablecast VOD Server has a workable MPEG-2 file on-disk, it can begin transcoding it into the final h.264 file.  The speed of this step will depend on the age of the Cablecast VOD Server.  Older servers have less processing power, so they will take longer to transcode the file.
   
   Time: About 20 minutes
   
   
4. File Discovery
   Performed on the Cablecast VOD Server
   
   Once the file has been transcoded, all that is left is for Cablecast to discover it, so that it can be made available for viewing.
   Time: Up to 30 seconds

Adding the above time, we can see that this example file would take about 83 minutes to process.  It is important to note that multiple files may be in process at a time, e.g. a file could be transcoding on the Cablecast VOD Server while another file is transferring, and a third file is being prepared.  Furthermore, if you have multiple SX Video Servers, each server can prepare a file simultaneously.