r128x, a tool for loudness measurement of files on macOS.

March 25, 2026 ยท View on GitHub

Download on the App Store

Both the GUI version and the CLI version require macOS 14 since v0.7.0 release. However, if you want to compile, then Xcode 16.4 and macOS 15 Sequoia is required since v0.8.0 release as the develop environment for r128x-cli app. If GUI app, then Xcode 26 and macOS 26 is needed due to the support of icon composer projects.

This OS-requirement change is due to some needs of using newer SwiftUI APIs.

Tests proved that precompiled libraries in Audionuma's repo are still executable on macOS 15 (despite the CodeSign issues). Otherwise, I would probably hesistate to drop macOS 13 and earlier.

P.S.: Apple Silicon mac is a strong recommendation to run my fork since the libEBUR128 is completely written in Swift and the rewritten version is not hardware-accelerated as the previous C-language version. The C-language version has compilation issues on Apple Silicon while being archived for Mac App Store, hence the rewrite in Swift.

r128x-swiftui

r128x is released under GPLv3 license.

For releases earlier than 0.4, please check the repo under the previous maintainer:

Note: GPLv3 does not hinder the copies of the compiled binaries to be sold as long as the source code is publicly available.

Binaries

Binaries of all versions are not provided anymore since the release of v0.5.1.

You are expected to either compile the binary by yourself or buy at Mac App Store.

The charged fee is not mandatory since you can always compile the binaries for your own purposes. However, I will really appreciate if you can buy a copy on Mac App Store to support the development and maintenance of this app.

For r128x-cli users, you have three options:

1. Mac App Store

Mac App Store GUI version (since v0.9.0) can also be used as a CLI. You just need to add an extra flag --cli:

/Applications/r128x-swiftui.app/Contents/MacOS/r128x-swiftui --cli --help
===========================================================
r128x - EBU R128 Loudness Measurement Tool

USAGE:
    r128x-swiftui --cli [OPTIONS] <file1> [file2] [file3] ...

ARGUMENTS:
    <file>    Audio file(s) to analyze

OPTIONS:
    --cli         Enable CLI mode (otherwise, this app will run in GUI mode)
    -h, --help    Show this help message (Only works when CLI mode is enabled)

EXAMPLES:
    r128x-swiftui --cli audio.wav
    r128x-swiftui --cli *.wav
    r128x-swiftui --cli song1.mp3 song2.flac song3.aac

OUTPUT:
    Results are displayed in tab-separated format:
    FILE    IL (LUFS)    LRA (LU)    MAXTP (dBTP)

SANDBOX COMPATIBILITY:
    In the Mac App Store version, the app will show permission dialogs
    to request access to your audio files when using CLI mode.
    This ensures compatibility with macOS sandbox security requirements.

2. Homebrew

brew tap shikisuen/r128x https://github.com/shikisuen/r128x.git
brew install shikisuen/r128x/r128x

3. Compile by yourself

Please read the next section.

Why the bloody hell you don't provide binary downloads of CLI directly on GitHub?

Because it is really hard to automatically manage the codesign-notarization process for a CLI app. This process is necessary against potential hindrance from macOS built-in GateKeeper.

How to Compile

Xcode 26 or Swift 6.1 is recommended for the compilation. Apple always eager to push its latest toolchain as a hard requirement for compiling modern Xcode projects.

1. GUI app

WARNING: If you compile for distributing to someone else, you MUST change both the developer ID and the bundle identifier of the app in the Xcode project settings. You can go to Targets -> r128x-swiftui -> Signing & Capabilities and change these configurations.

  1. Use Xcode to open the r128x.xcodeproj project file.
  2. Menu: Product -> Archive.
  3. After the compilation finishes, the organizer shows up. If it doesn't show up, check Menu: Window -> Organizer.
  4. In the organizer, find your compiled archive, and then click the "Distribute App" button -> "Custom" -> "Direct Distribution".
  5. Specify your developer certificate during the process and finish the code-signing & notarization process.
  6. Export the app once the notarization is succeeded.

If not compile-for-share but for this computer only:

  1. Use Xcode to open the r128x.xcodeproj project file.
  2. Menu: Product -> Run.

2. CLI app

  1. Use Xcode to open the R128xSPM SPM Package from the ./SPMPackages folder.
  2. Menu: Project -> Archive.
  3. After the compilation finishes, the organizer shows up. If it doesn't show up, check Menu: Window -> Organizer.
  4. In the organizer, find your compiled archive, and then click the "Distribute App" button -> "Custom" -> "Direct Distribution".
  5. Specify your developer certificate during the process and finish the code-signing & notarization process.
  6. Export the app once the notarization is succeeded.

If not compile-for-share but for this computer only, you can use commandline to compile the project. Please refer to related Swift documentation.

Description

r128x is a tool for measuring Integrated Loudness, Loudness range and Maximum True Peak of audio files on the Mac OS X system with an Intel processor.

It uses libebur128 (https://github.com/jiixyj/libebur128) for the Integrated Loudness and Loudness Range measures.

It uses CoreAudio's AudioConverter service to oversample audio data and obtain the Maximum True Peak.

It uses CoreAudio ExtAudioFile's service to read the samples from an audio file.

You can build two different binaries from the sources : a command line utility (r128x-cli) and a graphical interface utility (r128x-swiftui).

Installation

You can build the executables from the Xcode project, or use the provided executables.

Just drag the executable file to your hard drive. /usr/local/bin/ should be a nice place to put the command line binary r128x-cli if you want it to be in your $PATH.

Usage

r128x-cli /some/audio/file.wav Will print out the file name, the Integrated Loudness in LUFS, the Loudness range in LU, the Maximum True Peak in dBTP. Will print an error message in case of unsupported file or if an error occurs during processing.

r128x-swiftui supports drag and drop of audio files. You can also use the file selector.

Issues

Channel mapping is static, using the default libebur128 channel mapping : L / R / C / LFE / Ls / Rs. You will have incorrect results if your file's channels mapping is different. As r128x uses CoreAudio to read audio files, only file formats/codecs supported by CoreAudio are supported by r128x.

RF64 Format Support

This version of r128x includes comprehensive support for detecting and handling RF64 audio files.

What is RF64?

RF64 is an extension of the WAV format designed to handle audio files larger than 4GB. It was defined by the European Broadcasting Union (EBU) and is commonly used for:

  • Long-duration recordings (>2 hours at high quality)
  • Multi-channel audio (5.1, 7.1 surround sound)
  • High sample rates and bit depths
  • Professional audio production

Current Implementation

Detection & Analysis:

  • r128x automatically detects RF64 files
  • Parses RF64 headers and extracts size information
  • Tests CoreAudio compatibility automatically

Smart Error Handling:

  • If CoreAudio supports RF64: processes normally
  • If not supported: provides detailed error messages with file information
  • Suggests practical workarounds and alternatives

Example Error Message:

RF64 file detected (8.50 GB data). CoreAudio does not support RF64 on this system. 
Consider converting to multiple smaller WAV files or using a different tool.

Workarounds for Unsupported RF64 Files

  1. Split into smaller files:

    ffmpeg -i large_file.rf64 -t 3600 -c copy part_%03d.wav

  2. Convert to supported format:

    ffmpeg -i file.rf64 -c:a pcm_f32le -ar 48000 output.wav

  3. Use professional tools:

    • Pro Tools, Logic Pro, Reaper (native RF64 support)
    • SoX audio processor
    • Audacity (with plugins)

Technical Notes

  • RF64 support will automatically work if Apple adds CoreAudio RF64 support in future macOS versions
  • The implementation follows EBU Technical Specification 3306
  • Handles both RF64 and BWF (Broadcast Wave Format) variants
  • Thread-safe and memory-efficient parsing

** CoreAudio may support new formats per certain macOS releases. Please file issues if new formats are implementable in r128x.**

Notice regarding the end of the French translation support in this Repository

The current maintainer Shiki Suen can only use the following languages:

  • English, Japanese, Simplified Chinese, Traditional Chinese.

These languages are secondary-supported languages which are not having the quality guaranteed:

  • French, Deutsch, Spanish, Brazilish (pt-BR), Russian, Turkish.

The App still offers localized UI for 2ndary languages (translated using AI services). Pull Requests for improving the translations of these 2ndary languages are still welcomed.