ASF File

What are ASF files and how to open them

Are you having problems opening an ASF file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your ASF files.

What is an ASF file?

ASF files have multiple uses, and Advanced Streaming Format is one of them. Read more about the other uses further down the page.

Advanced Streaming Format

ASF stands for Advanced Streaming Format, also sometimes referred to as Advanced System Format, and is a file format developed by Microsoft for streaming media files.

The ASF format is a so-called "container format", that merely dictates how data in the file is organized, not how e.g. the video chunks are encoded.

Files with the .asf extension contain three different objects including a header file, a data object, and an optional index object. The header file within the ASF container contains information about the media data. The data object is the actual media stream that the ASF file contains. The optional index object allows for random access to data within the ASF file.

ASF files allow for the compression of media files, making it easier to download the media files and stream them over the Web.

How to open ASF files

We have identified two ASF openers that are compatible with this specific type of ASF file.

Programs that open Advanced Streaming Format files

Last updated: August 5, 2026

All known file formats using extension .ASF

While Advanced Streaming Format is a popular type of ASF-file, we know of 4 different uses of the .ASF file extension. Different software may use files with the same extension for different types of data.

Acclaim Skeleton File

Files with the ASF file extension may contain skeleton data captured by an optical tracker.

The format was developed by Acclaim, a game development company, which has been doing research into motion capture for games for years.

Acclaim developed their own methods for creating skeleton motion from optical tracker data, and in the process invented two related file formats: A skeleton file and a motion file. Splitting the data into two made it possible to use the same skeleton data for multiple motions. ASF files hold the skeleton data, while the motion data is stored in AMC (Acclaim Motion Capture) files.

While we have not verified the apps ourselves yet, our users have suggested ten different ASF openers which you will find listed below.

Electronic Arts Sound File

A proprietary audio format used for music in Electronic Arts games.

You usually do not need to edit or view these files, as they only contain information usable by the software program that uses them.

Advanced Systems Format Video File

Advanced Systems Format Video File (.ASF) is a media container developed by Microsoft to store audio, video, and related data in a single file. It works as a wrapper around audio and/or video streams, allowing those streams to be compressed using various codecs, and optionally carrying metadata about title, author, copyright, and more. It was designed for both local playback and streaming media delivery across networks, letting content begin playing before the entire file is downloaded.

Microsoft's tools and frameworks typically create ASF files using Windows Media Audio (WMA) and Windows Media Video (WMV) codecs, though the container itself doesn't mandate any specific codec. An ASF file is produced by an encoder or application that packages media streams into this container, and is then read by media players or streaming clients that support ASF and the included codec(s).

On a technical level, ASF files are built from serialized objects identifiable by GUIDs, arranged in three top-level components: a mandatory Header Object (contains stream properties, duration, packet size, global file attributes, optional protection and metadata), a mandatory Data Object (contains packets carrying the actual media data), and optional Index Object(s) (enabling random access within the stream). The file begins with a fixed byte signature: in hexadecimal 30 26 B2 75 8E 66 CF 11 A6 D9 00 AA 00 62 CE 6C.

ASF opener for Windows

We have identified one ASF opener that is compatible with this specific type of ASF file.

Various apps that use files with this extension

These apps are known to open certain types of ASF files. Remember, different programs may use ASF files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about ASF file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.