Applies To: Windows Server 2003, Windows Server 2008, Windows Server 2008 R2

Windows Media Player and other players that are based on Windows Media technologies must communicate with a Windows Media server when streaming content over a network. The Windows Media server typically is not operated by a Microsoft content provider and is not under Microsoft's control.

When a player streams the content, it sends a log to the Windows Media server if the Windows Media server requests it. The content provider may also instruct the player to simultaneously forward the log to additional sites. Typically, the content provider generates statistics from these logs to improve the quality of its service. Other uses include billing and advertisement tracking. It is the responsibility of the content provider to disclose to the user whether these logs are shared with other companies and how the logs are used.

When logging is enabled in Windows Media Services, client logs are sent automatically by players that are based on the Windows Media Format and Microsoft Media Foundation Software Development Kits (SDKs). For unicast streams, the logs are sent to the Windows Media server. For multicast streams, the logs are sent to an alternate logging server (typically a Web server). Additionally, players that render Windows Media playlists (files with either an .asx or .wsx file name extension) containing LogURL tags submit their logs to the Windows Media server and to the URLs specified in the LogURL tags. (Windows Media Player 6.4 or earlier does not support LogURL tags defined in .asx files.) If a client is based on the Advanced Systems Format (ASF) specification, and not on Windows Media technologies, then the Independent Software Vendor (ISV) must verify that clients send the correct logs for each streaming scenario. Logging is a key feature that another provider's player application must implement to be Microsoft-compatible.

The log that is sent includes such details as: connection time, IP address, operating system version, Windows Media Player version, Player identification number (Player ID), date, protocol, and so on. The purpose of the Player ID is to allow content providers to identify the Player connection. If a unique Player ID is sent, content providers have the ability to correlate the information in its logs over multiple sessions. To protect user privacy, by default Windows Media Player sends an anonymous Player ID, which is comprised of two components: a well known static value and a randomly generated number that changes each time content is requested from a streaming media server.


Some content providers require that a unique Player ID be sent to access their content or services. The option to send a unique Player ID can be enabled on the Privacy tab in Windows Media Player.

See Also

Other Resources

Logging Model for Windows Media Services
Windows Media Player 12 privacy statement