loudness

A Python package (battle-tested C++ under the hood) for calculating integrated loudness (LUFS) with the ITU BS.1770 loudness algorithm. Useful for EBU R 128 compliance. Takes NumPy arrays as input (supports mono and stereo/multichannel). Based on libloudness (original implementation by Magnus Bro Kolstø, Nomono).

Installation

pip install loudness

Usage example

import soundfile as sf
import loudness

audio, sr = sf.read("audio.wav", dtype="float32")  # shape (samples, channels)
lufs = loudness.integrated_loudness(audio, sr)
print(f"{lufs:.2f} LUFS")

Performance

loudness is significantly faster than the alternatives when running on CPU:

Changelog

[0.2.0] - 2025-12-26

Added

• Add support for Python 3.14

Removed

• Remove support for Python 3.9

For the complete changelog, go to CHANGELOG.md

Development setup

• Install CMake and a C++ compiler
• pip install numpy pybind11 build scikit-build-core
• python -m build --wheel
• Install the built wheel
• pytest

Alternatives (Python)

| Name | Github stars | License | Last commit | |---------------------------------------------------------|-----------------------------------------------------------------------------|--------------------------------------------------------------------------|----------------------------------------------------------------------------------| | jaxloudnorm | | | | | loudness | | | | | PALA | | | | | pyebur128 | | | | | pyloudness | | | | | pyloudnorm | | | | | torchaudio | | | |