acx

.acxACX Audio File

Audible, Inc. · 2011

Developer
Audible, Inc.
Category
Audio
MIME Type
audio/x-acx
First Released
2011
Open Format
No
File Signature
Not applicable for typical ACX submissions; it refers to the underlying audio format's signature.
At a Glance
.acx
ACX Audio File

ACX files are proprietary audio files used exclusively for audiobook creation and distribution through the ACX platform.

Reviewed on June 2, 2026
Compression
Typically MP3 (Lossy), but based on underlying audio format specifications
Transparency
N/A
Editability
Low (requires re-exporting from original project)
Best for
Audiobook submission

Key Features

  • Designed for audiobook production and distribution.
  • Ensures adherence to strict technical quality standards.
  • Facilitates upload to major audiobook marketplaces.
  • Proprietary format tied to the ACX platform.

Best For

  • Authors and narrators creating audiobooks for ACX.
  • Ensuring audiobook quality meets platform standards.
  • Distributing completed audiobooks through Audible, Amazon, and iTunes.

Less Ideal For

  • General music listening.
  • Editing or mixing audio.
  • Sharing audio files with friends or collaborators outside ACX.
  • Using as a standard audio playback format.

Common Use Cases

  • Submitting finished audiobook chapters to ACX.
  • Archiving audiobook projects before distribution.
  • Providing final audio files to authors and publishers via ACX.

How to Open It

  1. ACX files are not meant for direct playback. You must upload them to the ACX platform through your ACX account.
  2. Review the ACX Audiobook Production Guidelines for specific technical requirements before creating your ACX files.
  3. Ensure your audio is properly exported (e.g., as MP3) and meets all specifications before packaging as ACX submissions.

What is a .acx file?

ACX files are audio files specifically designed for audiobooks. They are used as part of the ACX (Audiobook Creation Exchange) platform, which connects authors, narrators, and publishers to create and distribute audiobooks. These files typically contain the final recorded and mastered audiobook content, ready for upload to platforms like Audible, Amazon, and iTunes. Due to their specialized nature, they are not intended for general audio playback or editing by consumers.

Programs That Open .acx Files

PlatformProgram
WindowsACX Audiobook Creation ExchangeFreeOfficial
macOSACX Audiobook Creation ExchangeFreeOfficial
Web BrowserACX.comFreeOfficial

How to Convert .acx Files

FormatMethod
.MP3Export from DAW, Online Converters (use with caution)

Common Problems with .acx Files

⚠️ File rejected by ACX due to technical specifications.
Carefully review ACX's detailed Audiobook Production Guidelines and ensure your exported audio (often MP3) meets all requirements for sample rate, bit depth, peak normalization, and file naming.
⚠️ Cannot play the ACX file directly on my computer.
ACX files are intended for upload, not direct playback. You need to upload the correctly formatted audio file (usually MP3) to the ACX platform. The ACX system handles the final packaging and distribution.

Frequently Asked Questions

What is an ACX file?

An ACX file is an audio file formatted specifically for submission to the ACX platform for audiobook creation and distribution.

Can I listen to an ACX file like an MP3?

No, ACX files are not designed for direct playback. They are submission files that must meet strict technical requirements set by ACX.

How do I create an ACX file?

You don't 'create' an ACX file directly. You produce your audiobook in a standard audio format (like MP3) that meets ACX's specifications and then upload it to the ACX platform, where it's processed as an 'ACX file' for distribution.

Technical Details

ACX files are essentially MP3 or other standard audio formats packaged in a way that adheres to ACX's specific technical requirements for audiobook narration. This includes detailed specifications for file naming, bit depth, sample rate, and peak normalization to ensure consistent quality across the platform. They are not a fundamentally new audio codec but rather a specific audio file submission format.

Did You Know?

The ACX platform is a joint venture between Audible (an Amazon company) and Authors Guild.
ACX files ensure consistency and quality required for audiobooks sold on Audible, Amazon, and iTunes.

Security Information

ACX files themselves do not inherently pose a security risk, as they are audio content. However, always ensure you are downloading audio files from trusted sources or submitting them through the official ACX platform to avoid malicious content or intellectual property issues.

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