Microsoft KB Archive/254928

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Seamless Stream Switching with ASX Files

Article ID: 254928

Article Last Modified on 9/11/2006


  • Microsoft Windows Media Services 4.0
  • Microsoft Windows Media Services 4.1
  • Microsoft Windows Media Player 5.2
  • Microsoft Windows Media Player 6.0
  • Microsoft Windows Media Player 6.1
  • Microsoft Windows Media Player 6.2
  • Microsoft Windows Media Player 6.4

This article was previously published under Q254928


When you use a .asx file as a play list to stream multiple .asf files from a Windows Media server, the Windows Media Player buffers before playing each clip. To make the switch between clips smoother, you can add an event in the .asx file so that the player pre-buffers the next clip before finishing the first clip.


The <EVENT> tag can be used to trigger pre-buffering of a clip. For example:

<ASX Version = "3.0">
  <REF HREF = "mms://server1/welcome1.asf" />


  <REF HREF = "mms://server1/sample.asf" />

In this example, the EVENT NAME is a required field, but can be named anything you choose.

Some buffering may still occur between clips, but the buffering time should be reduced.

If the first clip is a lower bit rate than the second clip, the pre-buffering time is longer. This is because the initial buffering of the second clip is done at the bit rate of the first clip. If the bit rates of the clips are the same, the buffering time should be short.

NOTE: This sample does not work for Windows Media Player 7.

For more information on .asx files see the Windows Media Player SDK. This can be downloaded from the following location:


Additional query words: netshow wms wmp

Keywords: kbinfo KB254928