Advanced Streaming Format

ASF: The spark for the multimedia revolution

Advanced Streaming Format (ASF) is the spark that will ignite the digital multimedia revolution. ASF is the open standard file format in which multimedia content will be stored, streamed, and presented by the tools, servers, and clients of the multimedia vendors. It is this interoperability that will excite consumers and drive the digital multimedia revolution.

ASF provides benefits such as local and network playback, extensible media types, component download, scalable media types, prioritization of streams, multiple language support, environment independence, rich inter-stream relationships, and expandability. See About ASF for more information. Microsoft has made available an ASF 2.0 Preliminary Developers Kit that allows developers to get started in adding support for ASF 2.0 to their products. Microsoft plans to support ASF 2.0 in Windows NT 5.0, Internet Explorer 5.0, and updates to Windows 98 through an upgrade to NetShow version 3.x later in 1998.

Understanding the Differences Between ASF 1.0 and ASF 2.0
ASF 1.0 is a first generation streaming media file format developed by Microsoft in 1996. ASF 1.0 is supported by Windows NT 4.0, Windows 95, and Internet Explorer 4.0 through the NetShow services that ship as part of NetShow 1.x, 2.x, and 3.x (currently in limited beta). ASF 1.0 allows independent software vendors to start creating products using ASF today. A white paper regarding ASF 1.0 is available for download  (self extracting .Zip 56 Kb). Many companies have already created great products based on ASF 1.0.

Whether to develop to ASF 1.0 or ASF 2.0 today depends largely on what products you want to develop for. If your target is Windows NT 4.0, Windows 95, and Internet Explorer 4.0, then start developing using ASF 1.0. If you are interested in learning more about developing today using ASF 1.0, send e-mail to Include your name, company name, mailing address, phone, fax, and a description of what type of product you plan to develop using ASF 1.0.

If you want to develop to future platforms such as Windows NT 5.0, Internet Explorer 5.0, and updates to Windows 98, you can start using the ASF 2.0 Preliminary Developers Kit to get started.

Microsoft makes ASF Preliminary Developer's Kit (PDK) Available

This PDK will be of interest to developers of professional media tools, streaming media client and server software. Included in the PDK are libraries and sample code that allow developers to easily add functionality to their products to read and write files in the ASF format.

New ASF White Paper Available

This document gives a detailed overview of ASF's goals, history, status, and design.

Please Note:

The final version of the ASF specification is now available. Please proceed to Specification to download your copy.
Join the Discussion
If you would like to comment on the current ASF specification, please send an e-mail message to Make sure that your mail makes specific wording suggestions and includes a rationale.

If you would like to join the ASF mailing list, please visit the Listserv Management Information Page.

  1. What is ASF?
  2. What is the role of ASF in the multimedia world?
  3. Why is the multimedia world demanding a standard file format like ASF?
  4. How will ASF spark the multimedia revolution?
  5. What does ASF look like under the hood?
  6. What makes ASF good?
  7. How does ASF relate to AVI?
  8. How does ASF relate to other older formats such as MPEG-1, MPEG-2, and QuickTime?
  9. How does ASF relate to newer formats such as VXF, RA, RMFF, and VIV?
  10. How do I convert my existing content into ASF?
  11. Learn more about ASF.


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