Unblend

Unblend is a music source separation library with one API across HTDemucs, BS-RoFormer,and Mel-Band RoFormer. Unblend's Demucs backend runs ~6× (19–23x for single-stem extraction) faster at equal quality.

Installation

Prerequisites

• FFmpeg v4+ available in your PATH
• uv
• C/C++ compiler such as GCC, Clang, or MSVC

Install using uv

Create a virtual environment backed by a uv-managed Python:

uv python install 3.12
uv venv --managed-python --python 3.12
source .venv/bin/activate

Then install Unblend into that environment:

uv pip install unblend --torch-backend=auto

Temporary Installation

With uv, you can use the uvx command to run Unblend without installing it permanently on your system.

uvx unblend separate audio_file.mp3

Note: Unblend does not specify a specific PyTorch wheel. This means that GPUs will only work on Apple Silicon or PyTorch's default CUDA version on Linux when using uvx.

CLI Usage

After installing unblend, you can use it like the following:

# View separation options
unblend separate --help

# Separate one audio file
unblend separate audio_file.mp3

# Separate multiple audio files
unblend separate audio_file_1.mp3 audio_file_2.mp3

# Separate every audio file in a directory tree
unblend separate /path/to/music/folder

Programmatic Use

Unblend provides a Python API for integrating source separation into your own application. Additionally, there is a Cog for HTDemucs which allows you to easily deploy it as a REST API. You can alternatively use the hosted version at Replicate.

Unblend can also run in the browser via ONNX. See the ONNX export notes and the unblend npm package docs for details.