What is MIME type "video/x-ms-asf"?

A MIME type is a string that tells browsers and other tools how to handle a particular kind of file.

video/x-ms-asf is a MIME type used by Windows Media files.
It defines a container format that holds audio, video, and metadata. This format supports smooth streaming over networks and often works with digital rights management.

Streaming media: It enables live and on-demand video playback over the internet.
Playback compatibility: It is optimized for Windows Media Player and similar software.
Metadata support: It can embed extra information like titles, authors, and licensing details.

It is tied to several file types such as the main ASF file, which serves as the core container. The ASX file works as a playlist, while WAX and WXV are variants that support similar media functionalities.

Associated file extensions

.asf, .asx, .wax, .wxv

Usage Examples

HTTP Header

When serving content with this MIME type, set the Content-Type header:


    Content-Type: video/x-ms-asf

HTML

In HTML, you can specify the MIME type in various elements:


    <a href="file.dat" type="video/x-ms-asf">Download file</a>

Server-side (Node.js)

Setting the Content-Type header in Node.js:


    const http = require('http');
    
    http.createServer((req, res) => {
      res.setHeader('Content-Type', 'video/x-ms-asf');
      res.end('Content here');
    }).listen(3000);

Associated file extensions

.asf, .asx, .wax, .wxv

FAQ

What is a MIME type?

A MIME (Multipurpose Internet Mail Extensions) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF's RFC 6838.

MIME types are important because they help browsers and servers understand how to process a file. When a browser receives a file from a server, it uses the MIME type to determine how to display or handle the content, whether it's an image to display, a PDF to open in a viewer, or a video to play.

MIME types consist of a type and a subtype, separated by a slash (e.g., text/html, image/jpeg, application/pdf). Some MIME types also include optional parameters.

How do I find the MIME type for a file?

You can check the file extension or use a file identification tool such as file --mime-type on the command line. Many programming languages also provide libraries to detect MIME types.

Why are multiple MIME types listed for one extension?

Different applications and historical conventions may use alternative MIME identifiers for the same kind of file. Showing them all helps ensure compatibility across systems.