What is MIME type "audio/atrac3"?

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

audio/atrac3 is a MIME type for files encoded with Adaptive Transform Acoustic Coding 3.
This codec, developed by Sony, compresses audio into small files while keeping sound quality at low bit rates.
It is built for efficient playback on portable media devices and streaming applications.
Supported files use the extensions AT3 and AA3.

Used in digital music players for optimized sound storage.
Helps software correctly route and play back ATRAC3 audio streams.
Designed to work well in low-bandwidth and portable environments.

For further technical details, visit ATRAC on Wikipedia.

Associated file extensions

.at3, .aa3

Usage Examples

HTTP Header

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


    Content-Type: audio/atrac3

HTML

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


    <a href="file.dat" type="audio/atrac3">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/atrac3');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.at3, .aa3

FAQs

Which software can open files with the audio/atrac3 MIME type?

Files served as audio/atrac3 are best opened with VLC media player or FFmpeg, which have reverse-engineered support for the codec. Historically, Sony's proprietary software like SonicStage or Connect Player was required to manage these files, specifically for Walkman and MiniDisc devices.

Do web browsers natively support audio/atrac3 playback?

No, modern browsers like Chrome, Firefox, and Safari do not support the ATRAC3 codec natively. To play audio on the web, you should convert .at3 or .aa3 files to widely supported MIME types like audio/mpeg or audio/mp4 (AAC).

How do I configure an Apache server to serve ATRAC3 files?

You can enable support by adding the MIME type definition to your .htaccess file or global configuration. Add the line AddType audio/atrac3 .at3 .aa3 to ensure the server sends the correct Content-Type header to the client.

What is the difference between the .at3 and .aa3 extensions?

While both use the ATRAC3 compression scheme, the extension usually indicates the container or origin. The .at3 extension is commonly associated with Sony gaming hardware (like the PSP) and raw data, whereas .aa3 is typically used by Sony's desktop software for encrypted or rights-managed music libraries.

How can I set up Nginx to handle audio/atrac3?

In Nginx, you should update your mime.types file or add a specific directive inside your server block. Use the configuration: types { audio/atrac3 at3 aa3; } to map the extensions to the correct MIME type.

Is audio/atrac3 still used for new development?

Generally, no; audio/atrac3 is considered a legacy format tied to older Sony ecosystem products. For modern applications, streaming, or storage, standard codecs like AAC or Opus are preferred due to better compression efficiency and universal compatibility.

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.