IIS 7 Media Pack: Extending IIS How?

I have really become interested in Rich Media Content distribution specifically around Microsoft Silverlight and Windows Media Server.  Anyone who knows me however, knows that IIS is my first love.  One of the most compelling features of IIS is the ability to extend its functionality.  The IIS and Windows Media team have collaborated to create the IIS 7 Media Pack.

 What is the Media Pack?

The IIS media pack is a set of IIS modules created to support Rich Media Content Delivery.  Today it includes two modules a bit rate throttling module and a media playlist module.

 Bit Rit Throttling

The most common vehicle for delivering video and audio over the web is through Progressive Dowloands.  Simply put progressive download refers to a media file being dowloaded to the client machine and played via some type of a client such as Windows Media Player.  The player then begins playing the file most times before the file is completely downloaded.

The problem with progressive download is that there is no intelligence involved during the streaming process.  If bandwidth availability is inconsistent then so will the streaming experience.  The Bit rate throttling module works to change this experience.  It allows you to set to basic settings.  First it has a fast start setting.  This is something that comes from the Windows Media Server world.  In a nutshell the module determines the media files encoded bitrate and uses that the figure out how many seconds are in the file.  Once that is determine the web server will quickly send a configured amount of content down to the client immediately.  The default value is 20 seconds.  This means that the first 20 seconds of the file is downloaded to the client for the media player begins playing the file.  This essentially means that the content being played is always 20 seconds ahead of the download.  This provides for a better experience and requires less buffering which is commonly something associated with progressive downloads (see YouTube when you don't have the fastest connection). 

The other setting allows you to throttle the bandwidth above or below the encoded bitrate.  This provides for more efficient streaming experience. 

Bit Rate Throttling has a tremendous impact because it allows you to save on bandwidth cost.  Why? Because a large amount progressive downloads are not watched/listened to in their entirity.  However, the file often is still completely downloaded to the client.  Bit Rate throttling limits the amount of a file tha is actually being downloaded the client and thus saves the bandwidth needed for sending that file.

 Web Server Playlist

Web Server allow you to utilize IIS for generating media playlist.  It supports multiple file formats (not just wmv or wma) and supports key scenarios such as monetization (have the ability to place ads alongside progressive download media).  You can even control the playback experience by disabling fast forward, rewind, and select functionality.

These two features essentially extend IIS to run as a simple media streaming server.  There are scenarios where WMS will always make sense however if you want a simple solution for distributing on-demand content, the combination of IIS 7 and the media pack are great tools for accomplishing that task.

 See more information on Bit Rate Throttling Here:  http://blogs.iis.net/chriskno/archive/2007/09/25/announcing-the-bit-rate-throttling-module-customer-technology-preview.aspx

 see more information on the IIS Playlist Feature Here:  http://blogs.iis.net/vsood/archive/2008/02/28/iis-7-media-pack-web-playlists-is-live.aspx