What is MIME type "audio/x-midi"?

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

audio/x-midi signals that a file holds MIDI data. It does not contain actual recorded sound. Instead, it stores instructions for synthesizers to generate music.
When a program opens an audio/x-midi file, it reads note, timing, and control data. This lets digital instruments play the music as designed.

Main purpose: It guides software on how to produce musical sounds without storing large audio streams.
Use cases: Digital composing, music editing, interactive applications, and legacy games.
Efficiency: Files are typically very small due to storing instructions, not full audio.
Technical note: The "x-" prefix shows it is a common, non-standard MIME type variant.

Files associated with this MIME type include formats like MIDI, MID, AIFF, AIF, and IEF.
For more details, see MIDI on Wikipedia.

Associated file extensions

.aiff, .midi, .mid, .aif, .ief

Usage Examples

HTTP Header

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


    Content-Type: audio/x-midi

HTML

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


    <a href="file.dat" type="audio/x-midi">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', 'audio/x-midi');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.aiff, .midi, .mid, .aif, .ief

FAQs

What is the difference between audio/x-midi and standard audio files?

Unlike formats like MP3 or WAV, audio/x-midi does not contain actual recorded sound waves. Instead, it stores musical instructions (notes, pitch, velocity) that tell a digital synthesizer how to generate the audio. This distinction makes files like .mid significantly smaller than recorded audio files.

Why won't audio/x-midi files play directly in my web browser?

Most modern browsers (Chrome, Firefox, Edge) have removed native support for playing MIDI files directly via the <audio> tag. To play audio/x-midi content on a webpage today, developers usually rely on JavaScript MIDI libraries or convert the files to formats like MP3 or OGG.

Should I use audio/x-midi or audio/midi?

You should generally prefer the standard MIME type audio/midi for new applications. The audio/x-midi type is a non-standard variant often found in legacy systems or older server configurations. However, most software that handles MIDI will recognize both types.

How do I configure Apache or Nginx to serve audio/x-midi?

You can map the relevant file extensions to this MIME type in your server's configuration files.

Apache: Add AddType audio/x-midi .mid .midi to your .htaccess file.
Nginx: Add audio/x-midi mid midi; inside the types { ... } block in nginx.conf.

What does the "x-" prefix mean in audio/x-midi?

The "x-" prefix indicates that the MIME type is non-standard or was experimental when first introduced. While audio/midi is the registered standard with IANA, audio/x-midi remains common due to its widespread use in early web development and legacy software support.

Why is the file size for audio/x-midi so small?

Files served as audio/x-midi are highly efficient because they only store performance data (which note to play, when, and how loud) rather than sampled sound. A complex song can be stored in a few kilobytes, whereas the same song in .aiff or WAV format could require tens of megabytes.

Are audio/x-midi files safe to open?

Generally, yes, as they contain data instructions rather than executable code. However, legacy media players have occasionally had vulnerabilities related to parsing malformed MIDI headers. It is best practice to keep your media software updated when opening files from unknown sources.

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.