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

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

audio/x-caf is a MIME type that tells software a file stores audio in the Apple Core Audio Format.

This format was designed to handle high-quality audio data. It supports large file sizes and multiple audio channels. It can also store rich metadata alongside the audio.

Files using this format often carry the extension CAF.

Professional audio production – Used for recording and editing high-resolution sound.
Flexibility – Supports uncompressed and compressed audio data.
Integration with Apple ecosystems – Common in macOS and iOS applications.

For further details, check the external documentation.

Associated file extensions

.caf

Usage Examples

HTTP Header

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


    Content-Type: audio/x-caf

HTML

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


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

Associated file extensions

.caf

FAQs

Which web browsers support audio/x-caf?

Native support for audio/x-caf is generally restricted to Apple Safari on macOS and iOS. Major cross-platform browsers like Google Chrome, Firefox, and Microsoft Edge do not typically support playing .caf files directly in the HTML5 <audio> element.

How do I configure an Apache server to serve .caf files correctly?

You should ensure the MIME type is mapped to the file extension in your configuration or .htaccess file. Add the line AddType audio/x-caf .caf to tell the server to send the correct content-type header to the client.

Why would I use CAF instead of WAV or AIFF?

The primary advantage of the Core Audio Format is that it overcomes the 4GB file size limit found in standard WAV and AIFF formats. CAF uses 64-bit file offsets, allowing for extremely large recordings, which makes it ideal for long-duration recording sessions or high-resolution multi-channel audio.

How can I play audio/x-caf files on Windows?

Windows does not support the Core Audio Format natively. To play these files, you will need cross-platform media players like VLC Media Player or audio editing software like Audacity, or you must convert the file to a widely supported type like audio/mpeg.

What is the correct Nginx configuration for audio/x-caf?

In your nginx.conf or mime.types file, you need to associate the extension with the MIME type. Add the line audio/x-caf caf; inside the types { ... } block to ensure Nginx serves the file correctly.

What does the 'x-' prefix mean in this MIME type?

The x- prefix indicates that audio/x-caf is a non-standard or proprietary type (specifically from Apple) rather than a standard registered with the IANA. While it is the de facto standard for handling CAF files, developers should be aware that support is often limited to the Apple ecosystem.

How do I convert a CAF file for general web usage?

Because audio/x-caf has poor browser support, it is best to convert it to MP3 or AAC using a tool like FFmpeg. You can run ffmpeg -i input.caf output.mp3 to create a file compatible with standard audio/mpeg players.

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.