What is MIME type "text/smil"?

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

The MIME type text/smil is used for documents written in the Synchronized Multimedia Integration Language (SMIL). It relies on an XML-based format to coordinate multimedia elements such as audio, video, text, and images with precise timing.

Creates timed multimedia presentations.
Controls the sequence and synchronization of media components.
Supports complex layouts, transitions, and interactivity in digital signage and broadcast applications.
Facilitates web-based multimedia content with scheduled media playback.

Files using this MIME type include those with extensions like SMI, SMIL, and SML.

Explore more about the language on Wikipedia.

Associated file extensions

.smi, .smil, .sml

Usage Examples

HTTP Header

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


    Content-Type: text/smil

HTML

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


    <a href="file.dat" type="text/smil">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', 'text/smil');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.smi, .smil, .sml

FAQs

How do I configure a web server to serve text/smil?

To ensure browsers or media players interpret the file correctly, you must set the MIME type in your server configuration. For Apache, add the line AddType text/smil .smil .smi .sml to your .htaccess or config file. For Nginx, add text/smil smil smi sml; to your mime.types file.

Do modern web browsers support text/smil natively?

No, most modern browsers (Chrome, Firefox, Edge) have deprecated or removed native support for SMIL (specifically SMIL animation in SVG is different from full SMIL documents). For web-based multimedia synchronization, developers should now use HTML5 <audio> and <video> tags combined with JavaScript.

What is the difference between text/smil and application/smil?

Both MIME types refer to the same Synchronized Multimedia Integration Language. While application/smil is the current standard registered with IANA, text/smil was widely used historically because the format is human-readable XML. Legacy systems and older media players often prefer or require text/smil.

Why is my .smi file treated as a caption file instead of a presentation?

The .smi extension suffers from a collision; it is used for both SMIL presentations and Microsoft's SAMI (Synchronized Accessible Media Interchange) caption format. You must check the file header: SMIL starts with <smil>, while SAMI starts with <sami>. Ensure your server sends text/smil for presentations and a caption-specific type for SAMI.

Is text/smil still used in mobile technology?

Yes, SMIL is the underlying technology for MMS (Multimedia Messaging Service). When you send a picture message with text and audio on a phone, a hidden SMIL file often coordinates the layout and timing of the slide show.

How can I open a file with the text/smil content type?

You can open these files using multimedia players that support the standard, such as RealPlayer or older versions of QuickTime. Since the files are text-based XML, you can also view and edit the code using any standard text editor like Notepad or VS Code.

General 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.