What is MIME type "audio/atrac-advanced-lossless"?

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

The MIME type audio/atrac-advanced-lossless denotes files that use an advanced lossless encoding method. It compresses audio data without any degradation to the original sound quality.
This technique was developed by Sony to combine efficient storage with high-fidelity audio.

Common products in this family include files like AT3, OMG, OMA, AA3, and AAL.

Key uses and characteristics include:

Storage of high-quality audio while minimizing file size
Usage in portable devices and digital audio players, especially in Sony ecosystems
Preservation of the original recording’s details for archival and professional use

This format is ideal where conserving every nuance of the original sound is critical. For more details on MIME types, visit this reference.

Associated file extensions

.at3, .omg, .oma, .aa3, .aal

Usage Examples

HTTP Header

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


    Content-Type: audio/atrac-advanced-lossless

HTML

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


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

Associated file extensions

.at3, .omg, .oma, .aa3, .aal

FAQs

Which software can open files with the audio/atrac-advanced-lossless MIME type?

Files served with this MIME type generally require Sony proprietary software, such as Sony Music Center for PC (formerly SonicStage) or Sound Forge. While some third-party tools like ffmpeg have partial support for older ATRAC formats, decoding Advanced Lossless files often fails without specific Sony codecs.

Do web browsers support playback of audio/atrac-advanced-lossless?

No, standard web browsers like Chrome, Firefox, and Safari do not natively support the ATRAC Advanced Lossless codec. To play audio on the web, you should convert these files to widely supported formats like audio/mpeg (MP3) or audio/wav before embedding them.

How do I configure an Apache server to serve .aal or .aa3 files correctly?

You can ensure the correct MIME type is sent by adding an AddType directive to your server configuration or .htaccess file. Add the line AddType audio/atrac-advanced-lossless .aal .aa3 .oma to associate these Sony-specific extensions with the correct Content-Type header.

What is the difference between this format and MP3?

ATRAC Advanced Lossless is a lossless format, meaning it compresses audio without discarding any data, preserving the original quality perfectly. In contrast, MP3 is a lossy format that discards some audio data to achieve smaller file sizes. For archival purposes, the lossless format is superior, though less compatible.

Why does my browser download the file instead of playing it?

When a browser encounters the audio/atrac-advanced-lossless Content-Type, it does not recognize it as a playable media format. Consequently, the browser defaults to downloading the file so the user can open it with a local desktop application compatible with extensions like .oma or .aal.

Are .oma and .aa3 files always lossless?

Not necessarily. The extensions .oma and .aa3 are container formats that can hold various types of ATRAC data, including lossy versions like ATRAC3plus. The MIME type audio/atrac-advanced-lossless specifically indicates that the file contains the high-fidelity Advanced Lossless stream.

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.